Relining rebasing and repair of complete denture/ dental courses

RELINING, REBASING AND

REPAIR OF COMPLETE DENTURE

INDIAN DENTAL ACADEMYINDIAN DENTAL ACADEMYLeader in continuing Dental EducationLeader in continuing Dental Education

www.indiandentalacademy.comwww.indiandentalacademy.com

ContentsContents ► INTRODUCTION► DEFINITION► TREATMENT RATIONALE► INDICATIONS and CONTRAINDICATIONS► PRETREATMENT PROCEDURES► REQUIREMENTS OF SUCCESSFUL MATERIALS► TYPES OF RESILIENT LINERS► REVIEW OF LITERATURE► CLINICAL IMPRESSION PROCEDURES► LABORATORY PROCEDURES► CAUSES OF FRACTURE IN DENTURES► MATERIALS USED FOR DENTURE REPAIR► METHODS FOR REPAIR► METHODS TO STRENGTHEN THE REPAIRED PORTION► PREVENTION OF DENTURE FRACTURE► SUMMARY ► REFERENCES www.indiandentalacademy.com

INTRODUCTIONINTRODUCTION•Both biological supporting tissues and materials used in complete denture fabrication are vulnerable to time- dependent changes. •When denture needs to be refitted, it usually indicates undermined retention, sore spots, and variable denture bearing tissue hyperemia.•The need for “servicing” complete dentures to keep pace with the changing surrounding and supporting tissues is mandatory. •The relining and rebasing of complete dentures involves solving all of the problems encountered in the construction of new dentures, except positioning individual teeth.•The materials are formulated to be soft, resilient and help to form intervening cushion, consequently the transmission of masticatory forces are equalized by eliminating pressure spots. This results in reduced trauma to supporting tissues without sacrificing the contact.

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DEFINITIONSDEFINITIONS► RELINING –RELINING – -- It is the process of adding some material to the tissue side of a It is the process of adding some material to the tissue side of a

denture to fill the space between the tissue and the denture base. denture to fill the space between the tissue and the denture base. (Winkler) Or(Winkler) Or

- The procedure used to resurface the tissue side of a denture with - The procedure used to resurface the tissue side of a denture with new base material, thus producing an accurate adaptation to the new base material, thus producing an accurate adaptation to the denture foundation area. (GPT-8)denture foundation area. (GPT-8)

► REBASING –REBASING – - It is a process of replacing all the base material of a denture. - It is a process of replacing all the base material of a denture.

(Winkler) (Winkler) Or Or - The laboratory process of replacing the entire denture base material - The laboratory process of replacing the entire denture base material

on an existing prosthesis. (GPT-8)on an existing prosthesis. (GPT-8)


TREATMENT RATIONALETREATMENT RATIONALE

► The foundation that supports a denture changes adversely as a result The foundation that supports a denture changes adversely as a result of varying degrees and rates of residual ridge resorption.of varying degrees and rates of residual ridge resorption.

► These changes may be insidious or rapid, but they are progressive These changes may be insidious or rapid, but they are progressive and inevitable and are accompanied by:-and inevitable and are accompanied by:-

Loss of retention and stability.Loss of retention and stability.

Loss of vertical dimension of occlusion.Loss of vertical dimension of occlusion.

Loss of support for facial tissues.Loss of support for facial tissues.

Horizontal shift of dentures:- Incorrect occlusal relationships.Horizontal shift of dentures:- Incorrect occlusal relationships.

Reorientation of occlusal plane.Reorientation of occlusal plane.

Reline Rebase Reline Rebase

Minimal to moderate Moderate to maximal Minimal to moderate Moderate to maximal

changes changeschanges changeswww.indiandentalacademy.com

► The reasons for relining are:-The reasons for relining are:- 1) 1) To Improve Retention & Stability:-To Improve Retention & Stability:-

- Loss of fit will make the maintenance of peripheral seal impossible - Loss of fit will make the maintenance of peripheral seal impossible and will greatly impair the retentive effects of adhesion & cohesion.and will greatly impair the retentive effects of adhesion & cohesion.

- It may permit a rocking & tilting of the denture during function and - It may permit a rocking & tilting of the denture during function and in extreme cases in the lateral movement.in extreme cases in the lateral movement.

2) 2) To Restore the Vertical Dimension:-To Restore the Vertical Dimension:-

- If the vertical dimension to which a denture was made is reduced, - If the vertical dimension to which a denture was made is reduced, masticatory efficiency is impaired, but the previous efficiency can masticatory efficiency is impaired, but the previous efficiency can usually be restored by relining.usually be restored by relining.

3) 3) To Improve the Appearance:-To Improve the Appearance:-

- Over-closure is noticed as the protrusion of the mandible and an - Over-closure is noticed as the protrusion of the mandible and an undue approximation of the nose and chin, giving an appearance of undue approximation of the nose and chin, giving an appearance of age.age.


4) 4) To Restore the Evenness of Occlusal Pressure:-To Restore the Evenness of Occlusal Pressure:-

- When there is any alteration in the fit of the dentures, there will be - When there is any alteration in the fit of the dentures, there will be some alteration of the pressure transmitted to the tissues when the some alteration of the pressure transmitted to the tissues when the teeth are brought into occlusion.teeth are brought into occlusion.

5) 5) To Relieve Pain:-To Relieve Pain:-

- If a denture has been worn with comfort and then becomes painful, it - If a denture has been worn with comfort and then becomes painful, it is usually due to the alteration in the supporting tissues allowing the is usually due to the alteration in the supporting tissues allowing the dentures to tilt, rock or move, and transmit undue pressure on one dentures to tilt, rock or move, and transmit undue pressure on one area.area.


INDICATIONSINDICATIONS

► Immediate dentures at 3-6 months after their original construction.Immediate dentures at 3-6 months after their original construction.► When the residual alveolar ridges have resorbed and the adaptation When the residual alveolar ridges have resorbed and the adaptation

of the denture bases to the ridges is poor.of the denture bases to the ridges is poor.► Persistent denture sore mouth.Persistent denture sore mouth.► Congenital or acquired oral defect: Congenital or acquired oral defect: (Acquired defect due to surgery (Acquired defect due to surgery

for malignancy, trauma, congenital defects like cleft palate)for malignancy, trauma, congenital defects like cleft palate)► The need for promotion of mucosal healing.The need for promotion of mucosal healing.► Irregular foundation: Irregular foundation: Sharp knife edge residual ridge, maxillary or Sharp knife edge residual ridge, maxillary or

mandibular tori, prominent myelohyoid ridge.mandibular tori, prominent myelohyoid ridge. ► Single denture opposing natural teeth.Single denture opposing natural teeth.► Radiation therapy for tumors of face and neck.Radiation therapy for tumors of face and neck.


CONTRAINDICATIONSCONTRAINDICATIONS

1) When an excessive amount of resorption has taken place.1) When an excessive amount of resorption has taken place.

2) When abused soft tissues are present. 2) When abused soft tissues are present.

3) When the patient complains of TMJ problems.3) When the patient complains of TMJ problems.

4) If the dentures have poor esthetics or unsatisfactory jaw relationships.4) If the dentures have poor esthetics or unsatisfactory jaw relationships.

5) If the dentures create a major speech problems.5) If the dentures create a major speech problems.

6) When severe osseous undercuts exist.6) When severe osseous undercuts exist.


PRETREATMENT PROCEDURESPRETREATMENT PROCEDURES

► TISSUE PREPARATION:-TISSUE PREPARATION:- 1) Excessive hypertrophic tissue should be surgically removed. The 1) Excessive hypertrophic tissue should be surgically removed. The

dentures can be used as a surgical splint.dentures can be used as a surgical splint. 2) Oral mucosa should be free of areas of irritation.2) Oral mucosa should be free of areas of irritation. 3) Removal of the dentures from the mouth during sleep several weeks 3) Removal of the dentures from the mouth during sleep several weeks

before treatment commences, if the patient wears his dentures during before treatment commences, if the patient wears his dentures during sleep.sleep.

4) The dentures should be left out of the mouth at least 2-3 days before 4) The dentures should be left out of the mouth at least 2-3 days before making the final impression.making the final impression.

5) Daily massage of the soft tissues is helpful to stimulate blood supply.5) Daily massage of the soft tissues is helpful to stimulate blood supply.


► DENTURE PREPARATION:-DENTURE PREPARATION:- 1) Pressure areas on the tissue surface of the dentures should be 1) Pressure areas on the tissue surface of the dentures should be

relieved.relieved.

2) Minor occlusal disharmony is corrected by selective grinding.2) Minor occlusal disharmony is corrected by selective grinding.

3) Small border inadequacies are corrected.3) Small border inadequacies are corrected.

4) A correct posterior palatal seal area should be established before the 4) A correct posterior palatal seal area should be established before the final impression. Green stick compound and autopolymerizing final impression. Green stick compound and autopolymerizing acrylic resin can be used for this purpose.acrylic resin can be used for this purpose.


► PRINCIPAL PITFALLS:-PRINCIPAL PITFALLS:- 1) Do not increase the occlusal vertical dimension.1) Do not increase the occlusal vertical dimension.

2) Multiple even contacts should be present in centric relation.2) Multiple even contacts should be present in centric relation.

3) Do not permit the maxillary denture to move forward during 3) Do not permit the maxillary denture to move forward during impression making.impression making.

4) Ensure that CR and CO are identical.4) Ensure that CR and CO are identical.

5) Ensure that an accurate PPS has been established.5) Ensure that an accurate PPS has been established.

6) An equal thickness of final impression material should be used.6) An equal thickness of final impression material should be used.


Ideal requirements of successful materialsIdeal requirements of successful materials

► Ease of processing ► Dimensional stability during and after processing► Low water absorption► Adequate bond strength to rigid denture base resin► High abrasion resistance: To resist rupture during use.► Permanent resiliency: It should retain its resilience for longer period► Colour stability► Minimum solubility in saliva: Plasticizer should not leach out ► No adverse effect on denture base: Like distortion, reduction of

strength, crazing or blanching.► Ease in cleansing► Biocompatibility


Types of Resilient linersTypes of Resilient liners

► Natural rubbers.

► Vinyl co-polymers.

► Hydrophilic polymers.

► Silicone based compounds.

► Acrylic based compounds.

► Treatment liners (soft conditioners)

Room temperature polymerized condensation silicone rubber.

γ-methacrylate propyl trimethoxy silaneheat polymerized silicone rubbers

(molloplast B )


Why soft denture liners be used rather than rebasing an acrylic denture base?

Soft liner serves as a Soft liner serves as a “shock absorber”“shock absorber”

Short term soft liner Long term soft liner

Chemically activated soft liner Poly methyl/ethyl methacrylate Mixed with 60%-80% plasticizer Dibutyl phthalate

Slipping motion permits rapid change in the shape of the soft liner and provides cushioning effect

•Heat activated Powders –acrylic resin polmers and

CopolymersLiquid – acrylic and plasticizers

•Silicone based compounds


LIMITATIONS IN USE OF SOFT LINERSLIMITATIONS IN USE OF SOFT LINERS

► Reduction in denture base strength Reduction in denture base strength ► Loss of softness and resilience Loss of softness and resilience ► Colonization of candida albicans Colonization of candida albicans ► Difficulty in keeping soft liners clean using normal denture Difficulty in keeping soft liners clean using normal denture

cleaning methods cleaning methods ► Dimensional instability Dimensional instability ► Failure of adhesion Failure of adhesion ► Difficulty in finishing and polishing Difficulty in finishing and polishing ► Change of color Change of color


Review of LiteratureReview of Literature► According to According to Lammie and StorerLammie and Storer, (1958), (1958) resilient liner could be resilient liner could be

useful in the complete lower denture where the patient shows a senile useful in the complete lower denture where the patient shows a senile atrophy, in developing maximal retention where the ridges have atrophy, in developing maximal retention where the ridges have bilateral undercut, in mouth where a hard median palatal raphae is bilateral undercut, in mouth where a hard median palatal raphae is associated with a poor retentive and in obturators for acquired and associated with a poor retentive and in obturators for acquired and congenital clefts of palate. congenital clefts of palate.

► Bates and SmithBates and Smith (1965)(1965) concluded that most of the soft denture concluded that most of the soft denture liners had satisfactory bond strength and showed that the heat cure liners had satisfactory bond strength and showed that the heat cure soft denture liners have intimate contact with diffused bonding when soft denture liners have intimate contact with diffused bonding when materials are cure against an acrylic dough. materials are cure against an acrylic dough.

► Wilson et al (1966)Wilson et al (1966) defined a conditioning material as a soft material defined a conditioning material as a soft material which is applied temporarily to the fitting surface of the denture for which is applied temporarily to the fitting surface of the denture for the purpose of allowing a more equal distribution of load, thus the purpose of allowing a more equal distribution of load, thus permitting the mucosal tissue to return to their normal position. They permitting the mucosal tissue to return to their normal position. They demonstrated liquid component contain a plasticizer and concluded demonstrated liquid component contain a plasticizer and concluded that dibutylpthalate and ethanol were also present. that dibutylpthalate and ethanol were also present.


► Kawano F. (1991) observed the effect of the proportion and thickness of soft lining materials on pressure distribution on the supporting tissue under the denture. He also suggested that soft lining materials act to distribute functional stress uniformly on the supporting tissues and a 3mm thickness of the soft lining material is most suitable for improving the pressure distribution on supporting tissues under the denture.

► Dootz E.K. et al (1993) in their study, on comparison of physical properties of eleven soft denture lining materials found that the accelerated aging of lining dramatically affected the physical and mechanical properties of many of the elastomers. According to them no single soft denture lining material proved to be superior to others. They have also stated that essential physical properties required for soft denture lining material have not been defined and the data obtained in this study would support the development of a specification for soft denture lining materials.


Linear dimensional change of heat-cured acrylic Linear dimensional change of heat-cured acrylic resin complete dentures after reline and rebase -resin complete dentures after reline and rebase - Edmond , Chow, and Clark (1998)Edmond , Chow, and Clark (1998)

► Twenty-two maxillary and mandibular complete denture bases with Twenty-two maxillary and mandibular complete denture bases with artificial teeth and fine crosses were marked on the incisal edges of artificial teeth and fine crosses were marked on the incisal edges of the central incisors and the supporting cusps of the second molar the central incisors and the supporting cusps of the second molar teeth. teeth.

► Distances between the marks were measured with a high resolution Distances between the marks were measured with a high resolution traveling microscope. traveling microscope.

► Heat-cured acrylic resin was processed.Heat-cured acrylic resin was processed.► Results of the rebasing procedure were similar to that of the reline Results of the rebasing procedure were similar to that of the reline

except that only 0.1% intermolar shrinkage was found on the except that only 0.1% intermolar shrinkage was found on the maxillary denture.maxillary denture.

► ConclusionConclusion. . Shrinkage was approximately 0.15 mm for an interarch Shrinkage was approximately 0.15 mm for an interarch distance of 50 mm. distance of 50 mm.

► CLINICAL IMPLICATIONSCLINICAL IMPLICATIONS► This study demonstrated that reline or rebase procedures did not This study demonstrated that reline or rebase procedures did not

cause clinically significant.cause clinically significant.www.indiandentalacademy.com

CLINICAL IMPRESSION PROCEDURESCLINICAL IMPRESSION PROCEDURES FOR RELINING OR REBASING FOR RELINING OR REBASING

► The Static Impression Technique. Closed-mouth techniqueThe Static Impression Technique. Closed-mouth technique

Open-mouth techniqueOpen-mouth technique

► The Functional Impression Technique.The Functional Impression Technique.► The Chairside Technique.The Chairside Technique.


Closed-mouth relining techniques- maxillary dentureClosed-mouth relining techniques- maxillary denture:-:-

- Dentures are used as impression trays.- Dentures are used as impression trays.

- Either the existing centric relation occlusion is used to seat the - Either the existing centric relation occlusion is used to seat the dentures with lining impression material or a new centric relation is dentures with lining impression material or a new centric relation is recorded with impression compound before impressions are made. recorded with impression compound before impressions are made.

Some closed-mouth techniques are:-Some closed-mouth techniques are:-


Technique A:- Technique A:- Shafer F.H and Miller W.H(1971)Shafer F.H and Miller W.H(1971) Centric Relation:-Centric Relation:- Centric relation is recorded before the impression is Centric relation is recorded before the impression is

made, using modeling compound or wax.made, using modeling compound or wax. Denture Preparation:-Denture Preparation:- Denture is prepared before making the Denture is prepared before making the

impression by relieving all large undercuts and by relieving 1.5-2mm impression by relieving all large undercuts and by relieving 1.5-2mm from the tissue surface. The borders are reduced 1-2mm except the from the tissue surface. The borders are reduced 1-2mm except the posterior border of maxillary dentures.posterior border of maxillary dentures.

Special Suggestion:-Special Suggestion:- A large part of the middle of the palatal portion of A large part of the middle of the palatal portion of the maxillary denture is removed for visibility in positioning the the maxillary denture is removed for visibility in positioning the maxillary denture during the impression making.maxillary denture during the impression making.

Border Molding:-Border Molding:- The borders of the dentures are reformed to their The borders of the dentures are reformed to their functional contours by using low-fusing modeling compound.functional contours by using low-fusing modeling compound.

Impression:-Impression:- ZOE impression paste. ZOE impression paste. During border molding and impression making, the patient closes During border molding and impression making, the patient closes lightly into the pre-made interocclusal record.lightly into the pre-made interocclusal record.

The impression of the exposed part of the palatal section is made The impression of the exposed part of the palatal section is made with quick-setting plaster.with quick-setting plaster.


Advantages:- Advantages:- 1) The opening of the palatal portion will allow better seating of the 1) The opening of the palatal portion will allow better seating of the

maxillary denture and alleviate the increase in vertical dimension maxillary denture and alleviate the increase in vertical dimension pitfall.pitfall.

2) The pre-made interocclusal record helps to position the dentures 2) The pre-made interocclusal record helps to position the dentures during the impression making and to orient the dentures on the during the impression making and to orient the dentures on the articulator.articulator.

3) The two-step impression technique will reduce the possibility of 3) The two-step impression technique will reduce the possibility of moving the maxillary denture forward during the final impression moving the maxillary denture forward during the final impression making. making.

Disadvantages:-Disadvantages:- 1) The possibility of moving the maxillary denture forward is still a 1) The possibility of moving the maxillary denture forward is still a

major problem.major problem. 2) The wax interocclusal record is not an accurate and safe record that 2) The wax interocclusal record is not an accurate and safe record that

the patient can close on several times without the possibility of the patient can close on several times without the possibility of damaging the record.damaging the record.

3) This technique does not suggest any solution for difficulties of 3) This technique does not suggest any solution for difficulties of relining both dentures at the same time.relining both dentures at the same time.www.indiandentalacademy.com

Technique B:- Technique B:- Hansen N.J(1964)Hansen N.J(1964) Centric Relation:-Centric Relation:- Existing centric occlusion and intercuspation are Existing centric occlusion and intercuspation are

used to seat the dentures.used to seat the dentures. Denture Preparation:- Denture Preparation:- Special Suggestion:-Special Suggestion:- A large part of the palatal section is prepared to A large part of the palatal section is prepared to

be removed as follows:-be removed as follows:- First, the outline of the area should be indicated and deepened on the First, the outline of the area should be indicated and deepened on the

polished surface up to half the thickness of the base. polished surface up to half the thickness of the base. Holes are drilled at 5-6mm intervals inside this groove. Holes are drilled at 5-6mm intervals inside this groove. This procedure is suggested for easy removal of the palatal portion This procedure is suggested for easy removal of the palatal portion

during packing and processing.during packing and processing. Border Molding:-Border Molding:- Low-fusing modeling compound(green stick). Low-fusing modeling compound(green stick). Impression:-Impression:- Wax that flows at mouth temperature, such as Kerr’s Wax that flows at mouth temperature, such as Kerr’s

impression wax(Iowa wax) – material of choice.impression wax(Iowa wax) – material of choice. Impression is made in two steps:-Impression is made in two steps:- - Impression of the labial flange- Impression of the labial flange - Crest of the alveolar ridge between the canines.- Crest of the alveolar ridge between the canines.www.indiandentalacademy.com

Advantage:-Advantage:-

Two-step impression technique will reduce the possibility of extreme Two-step impression technique will reduce the possibility of extreme forward movement of the maxillary dentures.forward movement of the maxillary dentures.

Disadvantage:-Disadvantage:-

1) Wax impression material is difficult to work with and the possibility 1) Wax impression material is difficult to work with and the possibility of distortion exists.of distortion exists.

2) Errors of existing centric occlusion can produce an inaccurate 2) Errors of existing centric occlusion can produce an inaccurate impression.impression.


Technique C:- Technique C:- Christensen F.T(1971)Christensen F.T(1971) Centric Relation:-Centric Relation:- Existing centric occlusion and intercuspation.Existing centric occlusion and intercuspation.

Denture Preparation:-Denture Preparation:-

Special Suggestions:-Special Suggestions:- The labial and palatal flanges of the denture are The labial and palatal flanges of the denture are perforated, perforations will decrease the pressure inside the denture perforated, perforations will decrease the pressure inside the denture during impression-making preventing displacement of maxillary during impression-making preventing displacement of maxillary denture.denture.

Border Molding:-Border Molding:- Low-fusing modeling compound Low-fusing modeling compound

Impression:-Impression:- No specific impression material recommended.No specific impression material recommended.

Disadvantage:-Disadvantage:- Increase in vertical dimension of occlusion during Increase in vertical dimension of occlusion during laboratory procedures. laboratory procedures.


Technique D:- Technique D:- Jordan L.G(1972)Jordan L.G(1972) Centric Relation:-Centric Relation:- Existing centric occlusion.Existing centric occlusion. Specific Suggestions:-Specific Suggestions:- 1) Denture periphery should be shortened to create a flat border.1) Denture periphery should be shortened to create a flat border. 2) A large opening should be prepared in the palatal portion of the 2) A large opening should be prepared in the palatal portion of the

maxillary denture.maxillary denture. 3) Adhesive tape is attached over the buccal and labial surfaces of 3) Adhesive tape is attached over the buccal and labial surfaces of

both dentures 2mm away from the denture borders.both dentures 2mm away from the denture borders. 4) With a knife-edge stone, a fairly deep groove should be cut into the 4) With a knife-edge stone, a fairly deep groove should be cut into the

buccal and labial surfaces of the dentures at the junction of the buccal and labial surfaces of the dentures at the junction of the impression material and filled with molten baseplate wax.impression material and filled with molten baseplate wax.

Border Molding:-Border Molding:- Not suggested, but slight amount of impression Not suggested, but slight amount of impression material should be left on the flattened borders during impression material should be left on the flattened borders during impression making.making.


Impression:-Impression:- Plaster of Paris or zinc oxide eugenol for first step of Plaster of Paris or zinc oxide eugenol for first step of impression making, and plaster of Paris for second step(palatal impression making, and plaster of Paris for second step(palatal portion).portion).

Disadvantages:-Disadvantages:- Even though it has been suggested that the patient Even though it has been suggested that the patient should not seat the denture by closing on it, the existing errors of should not seat the denture by closing on it, the existing errors of centric occlusion may produce some pressure points and a faulty centric occlusion may produce some pressure points and a faulty impression can result. impression can result.


Closed-mouth relining technique- mandibular denture:-Closed-mouth relining technique- mandibular denture:- Factors to be considered during the relining of a mandibular denture Factors to be considered during the relining of a mandibular denture

are :are :

Ridge relation, ridge form and the characteristics of the mucosa Ridge relation, ridge form and the characteristics of the mucosa covering the ridges.covering the ridges.

Technique E:- Technique E:- Gillis R.R(1960)Gillis R.R(1960) Centric Relation:-Centric Relation:- Existing centric occlusion used to seat dentures.Existing centric occlusion used to seat dentures.

Special Suggestion:-Special Suggestion:-

1) Loss of vertical dimension corrected by luting softened modeling 1) Loss of vertical dimension corrected by luting softened modeling compound to the occlusal surfaces of the mandibular posterior teeth.compound to the occlusal surfaces of the mandibular posterior teeth.

2) Patient asked to repeatedly pronounce letter “m.”2) Patient asked to repeatedly pronounce letter “m.”

3) Record is chilled, trimmed and slightly heated before returning to 3) Record is chilled, trimmed and slightly heated before returning to the patient’s mouth. Repeat procedure until correct occlusal vertical the patient’s mouth. Repeat procedure until correct occlusal vertical dimension is established.dimension is established.


4) Lower working impression made and poured and lower denture 4) Lower working impression made and poured and lower denture mounted on an articulator.mounted on an articulator.

5) Denture removed and cleaned and excessive undercuts removed 5) Denture removed and cleaned and excessive undercuts removed and is luted to the maxillary denture in maximum intercuspation.and is luted to the maxillary denture in maximum intercuspation.

6) Softened modeling compound is placed inside the mandibular 6) Softened modeling compound is placed inside the mandibular denture and the articulator closed against the lower cast to contact denture and the articulator closed against the lower cast to contact the incisal guide pin.the incisal guide pin.

7) With this procedure, the amount of vertical dimension indicated by 7) With this procedure, the amount of vertical dimension indicated by the thickness of the compound on the surface of the mandibular teeth the thickness of the compound on the surface of the mandibular teeth is transferred to the base of the mandibular denture.is transferred to the base of the mandibular denture.

8) Mandibular denture now is used as a tray for making the final 8) Mandibular denture now is used as a tray for making the final impression.impression.

Impression:-Impression:- Modeling compound at early stage.Modeling compound at early stage.

Zinc oxide-eugenol for secondary impression.Zinc oxide-eugenol for secondary impression.


Advantages:-Advantages:-

1) The loss of vertical dimension can be compensated for during 1) The loss of vertical dimension can be compensated for during relining procedures.relining procedures.

2) The error in centric occlusion can be reduced during the laboratory 2) The error in centric occlusion can be reduced during the laboratory stages.stages.

Disadvantages:-Disadvantages:-

1) Time consuming.1) Time consuming.

2) The procedure for establishment of occlusal vertical dimension is 2) The procedure for establishment of occlusal vertical dimension is questionable.questionable.


Open-mouth impression technique:-Open-mouth impression technique:- - Given by Boucher.- Given by Boucher.

- Only technique that describes a method for relining the mandibular - Only technique that describes a method for relining the mandibular and maxillary dentures at the same time.and maxillary dentures at the same time.

- Impressions are made independently, without utilizing the existing - Impressions are made independently, without utilizing the existing centric occlusion and a new centric relation record is established.centric occlusion and a new centric relation record is established.


Technique F:- Technique F:- Boucher C.O.(1973)Boucher C.O.(1973) Centric relation:-Centric relation:- Dentures used as record bases and jaw relations Dentures used as record bases and jaw relations

recorded after making secondary impressions.recorded after making secondary impressions. Denture Preparation:-Denture Preparation:- Posterior palatal seal is formed in modeling Posterior palatal seal is formed in modeling

compound before any changes made on tissue side of denture. 1mm compound before any changes made on tissue side of denture. 1mm space is provided inside the denture for new impression material and space is provided inside the denture for new impression material and the borders are shortened by 1mm to allow space for new impression the borders are shortened by 1mm to allow space for new impression material to form a new border.material to form a new border.

Special Suggestion:-Special Suggestion:- 1) Denture prepared for reline impression.1) Denture prepared for reline impression.2) Buccal surfaces of the lingual flanges are ground to minimise the 2) Buccal surfaces of the lingual flanges are ground to minimise the

pressure against the mylohyoid ridges and between the tissues of the pressure against the mylohyoid ridges and between the tissues of the floor of the mouth and the buccal sides of the lingual flangesfloor of the mouth and the buccal sides of the lingual flanges

3) The lingual flange between the premylohyoid eminences and labial 3) The lingual flange between the premylohyoid eminences and labial flange between the buccal notches are shortened by 1mm.flange between the buccal notches are shortened by 1mm.

4) A modeling compound handle is formed over the lower anterior teeth 4) A modeling compound handle is formed over the lower anterior teeth and an adhesive or masking tape is adapted over the polished and an adhesive or masking tape is adapted over the polished surfaces of both dentures and over the teeth. surfaces of both dentures and over the teeth. www.indiandentalacademy.com

Border Molding:-Border Molding:- If inadequate flanges- borders should be corrected If inadequate flanges- borders should be corrected with modelling compound.with modelling compound.

Impression:-Impression:- Zinc oxide-eugenol impression material. Zinc oxide-eugenol impression material. - 15 seconds after the denture has been placed in the mouth, the - 15 seconds after the denture has been placed in the mouth, the

patient is asked to pull his upper lip down and open his mouth wide. patient is asked to pull his upper lip down and open his mouth wide. This molds the impression material over the borders of the denture.This molds the impression material over the borders of the denture.

Advantages:-Advantages:- 1) The special trimming of the denture and making room 1) The special trimming of the denture and making room for the impression material will facilitate the making of a reasonable for the impression material will facilitate the making of a reasonable impression during the selective pressure impression technique impression during the selective pressure impression technique without any occlusal interference.without any occlusal interference.

2) A separate interocclusal record using already made impressions as 2) A separate interocclusal record using already made impressions as the recording bases will allow the operator to concentrate on the recording bases will allow the operator to concentrate on recording the jaw relation. recording the jaw relation.

3) It is possible to verify the centric relation record if necessary.3) It is possible to verify the centric relation record if necessary. 4) Interocclusal record, made with quick setting plaster, is a reliable 4) Interocclusal record, made with quick setting plaster, is a reliable

one. one. Disadvantages:-Disadvantages:- 1) This technique requires more clinical and 1) This technique requires more clinical and

laboratory time and the performance of the procedures is not easy. laboratory time and the performance of the procedures is not easy. www.indiandentalacademy.com

2) 2) Functional Impression Technique:-Functional Impression Technique:-► It depends upon the thorough understanding of the versatile

properties of tissue conditioners as functional impression materials.► Improvements in these materials includes their retaining compliance

for many weeks, their good dimensional stability and their excellent bonding to denture base.

► Soft tissues should be assessed first for hyperemia and denture for its compound may be needed before the placement of fresh mix of liner compound may be needed before the placement of fresh mix of liner as these materials have a tendency to slump during setting and less as these materials have a tendency to slump during setting and less they are adequately supported. they are adequately supported.

► The patients mandible guided to retruded position which is one of The patients mandible guided to retruded position which is one of maximum intercuspation (centric occlusion) to help stabilize the maximum intercuspation (centric occlusion) to help stabilize the denture while the lining material is setting. denture while the lining material is setting.

► Excess material is trimmed with hot scalpel.Excess material is trimmed with hot scalpel.


3) Chairside Technique:-3) Chairside Technique:-

- Cold cure acrylic is added to the denture and allowed to - Cold cure acrylic is added to the denture and allowed to polymerize in the mouth to produce an instant chairside polymerize in the mouth to produce an instant chairside reline/rebase.reline/rebase.


1) The materials often produce a chemical burn on the mucosa.1) The materials often produce a chemical burn on the mucosa.

2) The result often was porous and developed a bad odour.2) The result often was porous and developed a bad odour.

3) Colour stability was poor.3) Colour stability was poor.

4) If the denture was not positioned correctly, the material could4) If the denture was not positioned correctly, the material could

not be removed easily to start again.not be removed easily to start again.


LABORATORY PROCEDURE FOR RELININGLABORATORY PROCEDURE FOR RELINING

► ARTICULATOR METHOD:-ARTICULATOR METHOD:-

Impression is made in the Impression is made in the

denture to be relined. denture to be relined.

Denture impression is Denture impression is

poured in dental stone.poured in dental stone.


Modeling clay adapted denture,Modeling clay adapted denture,

blocking out all the denture blocking out all the denture

surfaces,except occlusal surfaces of surfaces,except occlusal surfaces of

the teeth. the teeth.

Stone is placed on the lowerStone is placed on the lower

member and smoothed withmember and smoothed with

spatula. Denture is settled is spatula. Denture is settled is

the stone mix.the stone mix.


Cast is attached to the upper member of theCast is attached to the upper member of the

articulator with dental stone.articulator with dental stone.

Modeling clay removed from Modeling clay removed from

denture surface.denture surface.


All impression material must be removedAll impression material must be removed

from the denture. from the denture.

Thin layer of resin must be removed Thin layer of resin must be removed

from the inferior of the denture from the inferior of the denture

with the acrylic bur. with the acrylic bur.


Borders are reduced 2-3mm with bur.Borders are reduced 2-3mm with bur.

Frena notches are deepened with Frena notches are deepened with

no.557 cross-cut fissure bur.no.557 cross-cut fissure bur.


Resin grindings removed withResin grindings removed with

stream of air.stream of air.

Posterior palatal seal is placed in the cast, Posterior palatal seal is placed in the cast,

unless provided in impression.unless provided in impression.


Paint cast with tinfoil substitute.Paint cast with tinfoil substitute.

Mix autopolymerizing resin and place in Mix autopolymerizing resin and place in

denture. Avoid air entrapment. denture. Avoid air entrapment.


Place resin on cast and in border reflectionsPlace resin on cast and in border reflections

Denture is seated in indentations, Denture is seated in indentations,

and articulator closed.and articulator closed.


Relined denture cured in pressure containerRelined denture cured in pressure container

at 15-20psi for 30min.at 15-20psi for 30min.

Relined denture removed Relined denture removed

and examined for voids and and examined for voids and

nodules.nodules.

Finished and polished.Finished and polished.www.indiandentalacademy.com

LABORATORY PROCEDURE FOR LABORATORY PROCEDURE FOR REBASING REBASING

► JIG METHOD:- JIG METHOD:-

Stone index formed on lower member

of duplicator or jig.

Denture mounted on its cast in a reline jig

with stone and secured with locknuts www.indiandentalacademy.com

Porcelain denture teeth are removed from denture by Porcelain denture teeth are removed from denture by

heating with alcohol torch or hot spatula. heating with alcohol torch or hot spatula. www.indiandentalacademy.com

Porcelain teeth replaced in their Porcelain teeth replaced in their

indentations in the stone indexindentations in the stone index

Adapt a layer of base plate wax to cast Adapt a layer of base plate wax to cast

and assemble the jigand assemble the jig


Wax-up the denture teeth to base plate wax,Wax-up the denture teeth to base plate wax, remove cast, flask and process with remove cast, flask and process with heat cure denture base resin.heat cure denture base resin.

Cured denture replaced on jig to checkCured denture replaced on jig to check occlusion, then finished and polished.occlusion, then finished and polished.


► FLASK METHOD:-FLASK METHOD:-

Denture is half flaskedDenture is half flasked

Silicone mold material painted Silicone mold material painted

on denture and teeth. on denture and teeth.


Flask is opened.Flask is opened.

Porcelain teeth Resin teethPorcelain teeth Resin teeth


Cast and investing stone painted Cast and investing stone painted

with tinfoil substitutewith tinfoil substitute

Cured denture ready forCured denture ready for

finishing and polishing.finishing and polishing.


REPAIR OF COMPLETE DENTUREREPAIR OF COMPLETE DENTURE


► Complete dentures often fractures when in function or when Complete dentures often fractures when in function or when dropped onto a hard surface. dropped onto a hard surface.

► The most common denture fractures are those along the maxillary The most common denture fractures are those along the maxillary and mandibular midline. and mandibular midline.

► The repair of dentures is a difficult part of prosthesis, which can be The repair of dentures is a difficult part of prosthesis, which can be often handled as a laboratory procedure, but a knowledge of often handled as a laboratory procedure, but a knowledge of preparation as well as the technical phase is essential for successful preparation as well as the technical phase is essential for successful repair.repair.


CAUSES OF FRACTURE OF DENTURECAUSES OF FRACTURE OF DENTURE1) 1) FRACTURE OF THE DENTURE BASE► Improper mandibular occlusal plane

A common problem is the recurrent midline fracture in maxillary complete denture opposing natural dentition. Uneven or deflective occlusal plane leads to defective occlusal contacts which deform the denture base and create a line of fatigue that results in a denture base fracture.

► High frenum attachments:A broad maxillary labial frenum that is attached close to the crest

of the ridge requires to be provided with relief during function, which results in a deep notch, and weakens the denture base, and it causes concentration of stress at that point and may lead to site of commencement of fracture.

► Occlusal morphology: Bilateral balanced occlusion is ideal for the denture stability.

Incorrect recording of occlusion, absence of balanced occlusion will results in abnormal stress being applied to the denture base during function (which causes midline fracture). www.indiandentalacademy.com

► Occlusal forces:Occlusal forces:

A low Frankfort mandibular plane angle (FMA) leads to increased A low Frankfort mandibular plane angle (FMA) leads to increased amount of occlusal forces to the underlying residual ridge which may amount of occlusal forces to the underlying residual ridge which may contribute to the increased incidence of denture base fracture.contribute to the increased incidence of denture base fracture.

Patients with an increased vertical dimension at occlusion are prone Patients with an increased vertical dimension at occlusion are prone to denture base fracture due to the excessive masticatory forces.to denture base fracture due to the excessive masticatory forces.

Beyli M.S. (1981)Beyli M.S. (1981) concluded that midline fracture of a denture base concluded that midline fracture of a denture base was a flexural fatigue failure resulting from cyclic deformation of the was a flexural fatigue failure resulting from cyclic deformation of the denture base during function. Buccally arranged upper posterior teeth denture base during function. Buccally arranged upper posterior teeth to the crest of the ridge will transmit flexing component of forces to to the crest of the ridge will transmit flexing component of forces to the midline of the denture during function and leads to midline the midline of the denture during function and leads to midline fracture.fracture.


► Denture base thickness:Denture base thickness:Insufficient thickness of the denture base lingual to incisal resulting Insufficient thickness of the denture base lingual to incisal resulting from improper waxing is heavily stressed under function and leads from improper waxing is heavily stressed under function and leads to midline fracture.to midline fracture.The denture lined with resilient denture base liners are more The denture lined with resilient denture base liners are more susceptible for fracture due to excessive reduction of the denture susceptible for fracture due to excessive reduction of the denture base to allow the space for liner material will result in thinning of base to allow the space for liner material will result in thinning of denture base and prone for fracture.denture base and prone for fracture.

► Inaccurate Relief:-Inaccurate Relief:- Self relieving impression technique has been employed, such as Self relieving impression technique has been employed, such as compression impression technique, usually in mouths exhibiting compression impression technique, usually in mouths exhibiting gross variations in the thickness of the mucous membrane the gross variations in the thickness of the mucous membrane the denture will flex over the hard areas of the palate and causes denture will flex over the hard areas of the palate and causes fracture.fracture.


► Stress Concentrators:-Stress Concentrators:-

Changes in surface profiles of denture acting as stress concentrators Changes in surface profiles of denture acting as stress concentrators include –Scratches, a median diastema, deep frenal notch weakens include –Scratches, a median diastema, deep frenal notch weakens the dentures and cause concentration of stress & lead to site of the dentures and cause concentration of stress & lead to site of commencement of fracture. commencement of fracture.

► Absence of Labial Flange:- Absence of Labial Flange:-

An open face denture is not as stiff as a flanged denture. Flexing will An open face denture is not as stiff as a flanged denture. Flexing will be more marked and is likely to result in fatigue fracture.be more marked and is likely to result in fatigue fracture.

► Incomplete Polymerization of Acrylic Resin:-Incomplete Polymerization of Acrylic Resin:-

If the curing cycle does not include a terminal heating period at If the curing cycle does not include a terminal heating period at 100ºC, the maximum degree of polymerization is not attained and the 100ºC, the maximum degree of polymerization is not attained and the strength of denture base will be reduced. strength of denture base will be reduced.

Packing the acrylic resin in advanced dough stage will leads to Packing the acrylic resin in advanced dough stage will leads to fractured or dislodged teeth in the complete denture.fractured or dislodged teeth in the complete denture.


► Previous Repair:-Previous Repair:-

When fractured previously in midline and repaired by cold cure acrylic When fractured previously in midline and repaired by cold cure acrylic resin – more susceptible to fatigue.resin – more susceptible to fatigue.

► Shape of the Teeth on the Denture:-Shape of the Teeth on the Denture:-

Because of wear, a wedging action on the upper denture results from Because of wear, a wedging action on the upper denture results from occlusion of teeth and locking of occlusion also appears to predispose occlusion of teeth and locking of occlusion also appears to predispose midline fracture.midline fracture.

► Overdenture abutment too prominent:-Overdenture abutment too prominent:-

will result in inadequate thickness in denture base. A patient with an will result in inadequate thickness in denture base. A patient with an overdenture can exert more occlusal force.overdenture can exert more occlusal force.


BREAKAGE OF A TOOTH OR TEETHBREAKAGE OF A TOOTH OR TEETH

► Cuspal Interference:-Cuspal Interference:-

Is confined to one tooth or teeth, in cases where the pressure is Is confined to one tooth or teeth, in cases where the pressure is heavier on one tooth than elsewhere, it will frequently cause the tooth heavier on one tooth than elsewhere, it will frequently cause the tooth to split.to split.

An anterior tooth may be broken off if there is excessive overbite with An anterior tooth may be broken off if there is excessive overbite with insufficient overjet.insufficient overjet.

► Faulty Tooth:-Faulty Tooth:-

Entirely confined to anterior porcelain pin teeth and an undetected Entirely confined to anterior porcelain pin teeth and an undetected flaw in the porcelain usually results in the tooth breaking across the flaw in the porcelain usually results in the tooth breaking across the line of the pins.line of the pins.


► Contraction of Acrylic Resin:-Contraction of Acrylic Resin:-

May be a cause of fracture in porcelain teeth set in an acrylic base.May be a cause of fracture in porcelain teeth set in an acrylic base.

It is due to large and uneven contraction of acrylic resin which It is due to large and uneven contraction of acrylic resin which occurs during polymerization, inducing excessive stresses in the occurs during polymerization, inducing excessive stresses in the porcelain teeth.porcelain teeth.

► Excessive Grinding of a Tooth:-Excessive Grinding of a Tooth:-

Excessive grinding of either the occlusal or ridge surface of a Excessive grinding of either the occlusal or ridge surface of a porcelain posterior tooth to weaken it, as to causes fracture.porcelain posterior tooth to weaken it, as to causes fracture.


MATERIALS USED FOR DENTURE REPAIRMATERIALS USED FOR DENTURE REPAIR

► Despite the favorable physical characteristics of the denture base Despite the favorable physical characteristics of the denture base resins, denture bases sometimes fracture.resins, denture bases sometimes fracture.

► In most instances such fractures may be repaired using compatible In most instances such fractures may be repaired using compatible resins.resins.

► These materials usually available in powder: liquid type similar to These materials usually available in powder: liquid type similar to those used for denture bases and are either heat activated or those used for denture bases and are either heat activated or chemically activated.chemically activated.

► Now, light activated acrylic resins have been shown to be fast and Now, light activated acrylic resins have been shown to be fast and effective denture repair materials.effective denture repair materials.


Carbon Fibers:-Carbon Fibers:-► Conventional dentures are reinforced by inclusions of carbon fiber Conventional dentures are reinforced by inclusions of carbon fiber

inserts in the palate to reduce the flexibility of denture base.inserts in the palate to reduce the flexibility of denture base.► Advantages:-Advantages:-

It reduces the incidence of fracture.It reduces the incidence of fracture.

Increases transverse and impact strength of poly methyl Increases transverse and impact strength of poly methyl methacrylate.methacrylate.


Black colour.Black colour.


Ultra-high-modulus Polyethylene Fibers (UHMPE):-Ultra-high-modulus Polyethylene Fibers (UHMPE):-► This material may be added either as a discrete woven insert into the This material may be added either as a discrete woven insert into the

denture base or as chopped fiber incorporated in the polymer powder denture base or as chopped fiber incorporated in the polymer powder before the resin is mixed.before the resin is mixed.

► The fiber is transparent and its inclusion in the polymer as chopped The fiber is transparent and its inclusion in the polymer as chopped fiber at a loading of 1% has resulted in an increase in impact strength fiber at a loading of 1% has resulted in an increase in impact strength exceeding that of commercially available “high impact” resins.exceeding that of commercially available “high impact” resins.

► When the material is inserted as a woven mat loadings of 20-30% are When the material is inserted as a woven mat loadings of 20-30% are reported.reported.


Glass Fibers:-Glass Fibers:-► Inclusions of glass fibers into acrylic resin has shown to improve Inclusions of glass fibers into acrylic resin has shown to improve

fatigue resistance, flexural strength and impact strength.fatigue resistance, flexural strength and impact strength.► The fibers are produced either as a woven mat and inserted into the The fibers are produced either as a woven mat and inserted into the

whole denture, or as individual fibers which are laid out in the region whole denture, or as individual fibers which are laid out in the region of a previous weakness.of a previous weakness.

► To obtain full benefit, care must be taken to position the fibers To obtain full benefit, care must be taken to position the fibers correctly.correctly.

► Enhances flexural properties of multi phase dental polymer, which Enhances flexural properties of multi phase dental polymer, which is due to proper impregnation of fibers with polymer matrix.is due to proper impregnation of fibers with polymer matrix.

► Composition: SiOComposition: SiO22- 55% H- 55% H22OO33- 15%- 15%

CaO- 22% BCaO- 22% B22OO33- 6% - 6%


SELECTION OF EDGE PROFIL FOR REPAIR SELECTION OF EDGE PROFIL FOR REPAIR ► Harrison & StansburyHarrison & Stansbury(1970)(1970) investigated the strength of denture investigated the strength of denture

repairs using, repairs using, A) Round JointA) Round Joint B) Rabbet JointB) Rabbet Joint C) Butt Joint C) Butt Joint

They concluded that rounded joint was superior to the rabbet and butt They concluded that rounded joint was superior to the rabbet and butt joints and it supports the principle that sharp angled surfaces promote joints and it supports the principle that sharp angled surfaces promote stress concentrations and the amount of stress concentration is directly stress concentrations and the amount of stress concentration is directly related to the degree and abruptness of surface change. related to the degree and abruptness of surface change.


► Beyli et al(Beyli et al(1980)1980) conducted a study on the “repair of fractured acrylic conducted a study on the “repair of fractured acrylic resin” and said that the criteria for satisfactory repair are:-resin” and said that the criteria for satisfactory repair are:-

Repair must be rapid.Repair must be rapid. Repaired structures must have adequate strength.Repaired structures must have adequate strength. Denture must retain dimensional accuracy during and after Denture must retain dimensional accuracy during and after repairs. repairs.

► Initial studies indicated that a 3mm gap width was suitable for repair Initial studies indicated that a 3mm gap width was suitable for repair and seven different edge profiles were prepared at this gap width:-and seven different edge profiles were prepared at this gap width:-

i) Knife edgei) Knife edge ii) Inverse knife edgeii) Inverse knife edge iii) Roundiii) Round iv) Lapiv) Lap v) Rabbetv) Rabbet vi) Inverse Rabbetvi) Inverse Rabbet vii) Ogeevii) Ogee


► They concluded that traditional butt joint for repair of fractured They concluded that traditional butt joint for repair of fractured dentures has been found to be inferior to the inverse knife edge, round dentures has been found to be inferior to the inverse knife edge, round lap, inverse rabbet and ogee joints. lap, inverse rabbet and ogee joints.

► The round joint appears to be the most convenient in practice because The round joint appears to be the most convenient in practice because of its easy preparation.of its easy preparation.

► The gap size should be 3mm or less to minimize the bulk of repair The gap size should be 3mm or less to minimize the bulk of repair material used which will reduce any colour differences. material used which will reduce any colour differences.

► A lower bulk of repair material will decrease the degree of shrinkage A lower bulk of repair material will decrease the degree of shrinkage


METHODS FOR REPAIRMETHODS FOR REPAIR

► Anterior Tooth Replacement:-Anterior Tooth Replacement:-

Fractured tooth is Fractured tooth is

removed by grindingremoved by grinding

with no. 8 round bur.with no. 8 round bur.

Care must be taken notCare must be taken not

to perforate dentureto perforate denture

base.base.

Labial gingival margin shouldLabial gingival margin should

be left intact to preserve be left intact to preserve

esthetics.esthetics.


Remove the resin from the lingual Remove the resin from the lingual

aspect of the denture base aspect of the denture base

Select a resin tooth Select a resin tooth

of same size andof same size and

shade and grind its shade and grind its

ridge lap for proper ridge lap for proper

positioning on the positioning on the

denture. denture. www.indiandentalacademy.com

Verify the tooth position and secure it in

position with sticky wax.

If the tooth position is

acceptable, pour a

plaster index or silicone

index onto the labial

surface of the tooth to

be replaced and on the

labial surfaces of adjoining teeth on each side.www.indiandentalacademy.com

After plaster sets, the index and tooth After plaster sets, the index and tooth

are separated and sticky wax removed.are separated and sticky wax removed.

Shallow indentations can be Shallow indentations can be

placed in the ridge laps of the placed in the ridge laps of the

tooth with a no. 6 bur to ensure tooth with a no. 6 bur to ensure

stronger repair.stronger repair. www.indiandentalacademy.com

Replace the index andReplace the index and

tooth on the denture,tooth on the denture,

and carefully paint the and carefully paint the

autopolymerizing resinautopolymerizing resin

to the lingual or palatalto the lingual or palatal

prepared area, prepared area,

allowing the resin to flow between allowing the resin to flow between

ridge lap and denture base. ridge lap and denture base.

Resin is added to build up slight Resin is added to build up slight

excess, which will be finished to excess, which will be finished to

original contour after polymerizing.original contour after polymerizing.


Repaired denture is placed in a pressure pot of warm water, and Repaired denture is placed in a pressure pot of warm water, and

cured at 20 psi for 30min.cured at 20 psi for 30min.


Remove the denture, and reduce the excess bulk with no. 8 bur and resin is smoothed with mounted rubber point and repair is polished with flour of pumice & handpiece mounted prophy cup.


► Posterior Tooth Replacement:- Posterior Tooth Replacement:-

Mount the denture in an articulatorMount the denture in an articulator

Remove the fractured resin tooth by grinding it with a no. 8 roundRemove the fractured resin tooth by grinding it with a no. 8 round

bur. Take care to bur. Take care to

preserve the facial preserve the facial

gingival margin of gingival margin of

the denture base andthe denture base and

not to perforate thenot to perforate the

base.base.


Ridge lap area of Ridge lap area of

denture is hollow grounddenture is hollow ground

and of the replacement and of the replacement

tooth is modified for thetooth is modified for the

correct placement of correct placement of

tooth.tooth.

Close the articulator Close the articulator

and check the occlusion. and check the occlusion.

If correct, seal the If correct, seal the

replacement tooth to replacement tooth to

opposing tooth with opposing tooth with

sitcky wax.sitcky wax.


Paint the autopolymerising resin into thePaint the autopolymerising resin into the

ridge lap area to seal the tooth to the ridge lap area to seal the tooth to the

denture base.denture base.


Place the denture in a pressure container of warm water, and cure it for 30min. at Place the denture in a pressure container of warm water, and cure it for 30min. at 20 psi. Adjust the occlusion and polish the repair. 20 psi. Adjust the occlusion and polish the repair.


► Repairing Fractured Denture:-Repairing Fractured Denture:- ( Non-separated Fracture)( Non-separated Fracture) Examine denture to determine theExamine denture to determine the

extent of the fracture. Gently flexingextent of the fracture. Gently flexing

denture will aid this determination, but denture will aid this determination, but

take care to prevent breakage.take care to prevent breakage.

If fractured denture self-approximates,If fractured denture self-approximates,

block the undercuts with clay,block the undercuts with clay,

and pour the repair cast.and pour the repair cast.


Full cast is not necessary if the Full cast is not necessary if the

fracture is small.fracture is small.

If undercut is there in If undercut is there in

the region of repair, the region of repair,

silicone mold materialsilicone mold material

can be placed in thecan be placed in the

undercut, resulting in undercut, resulting in

flexible cast permittingflexible cast permitting

removal of denture, removal of denture, www.indiandentalacademy.com

Remove the denture from the cast, and Remove the denture from the cast, and

widen the fracture line from beginning widen the fracture line from beginning

to end with no. 558 bur.to end with no. 558 bur.

Widened cut is beveled outwardsWidened cut is beveled outwards

to increase bonding area.to increase bonding area.


Dovetails can be placed on theDovetails can be placed on the

palatal surface to further strengthenpalatal surface to further strengthen

repair joint.repair joint.

Paint the stone cast with tinfoil Paint the stone cast with tinfoil

substitute and allow it to dry. If not substitute and allow it to dry. If not

completely dry then the resin may completely dry then the resin may

be coated, reducing repair strength.be coated, reducing repair strength.


Denture is replaced on the cast Denture is replaced on the cast

carefully.carefully.

Repair resin is painted in groove,Repair resin is painted in groove,

taking care not to create voids.taking care not to create voids.


Excess resin is built up Denture is secured to theExcess resin is built up Denture is secured to the for finishing cast with a rubber band, andfor finishing cast with a rubber band, and cured in a pressure containercured in a pressure container for 30 min.for 30 min.

Cured denture is removed, finished and polishedwww.indiandentalacademy.com

► Denture Fractured into Two or More Parts Denture Fractured into Two or More Parts

Examine the denture to determine that all pieces are present.Examine the denture to determine that all pieces are present.

Assemble the pieces and lute them with sticky wax.Assemble the pieces and lute them with sticky wax.www.indiandentalacademy.com

Modeling clay can be used to hold pieces while luting denture with sticky wax and Modeling clay can be used to hold pieces while luting denture with sticky wax and

reinforcing with wood sticks before removing from clay.reinforcing with wood sticks before removing from clay.www.indiandentalacademy.com

Alginate can be used Alginate can be used in in

pronounced undercuts pronounced undercuts

in mandibular denture.in mandibular denture.


Remove the Remove the denturedenture

from the cast. Bevel thefrom the cast. Bevel the

margins of each fragmentmargins of each fragment

with bur and make grooveswith bur and make grooves

and dovetail. Use wire and dovetail. Use wire

reinforcement to reinforcement to

strengthen the repair if strengthen the repair if

desired. desired.


Replace the denture on the cast, and paint autopolymerizing resin in each groove Replace the denture on the cast, and paint autopolymerizing resin in each groove and dovetail, and build up excess.and dovetail, and build up excess.

Secure the denture to the cast with plaster or rubber bands, Secure the denture to the cast with plaster or rubber bands,

and cure in a pressure container of warm water for 30min. at 20 psiand cure in a pressure container of warm water for 30min. at 20 psi


Finish and polish denturesFinish and polish dentures


► Fractured Denture with Section(s) Missing:-Fractured Denture with Section(s) Missing:- - - Make an impression with the denture in place to make a cast, Make an impression with the denture in place to make a cast,

particularly when a flange is broken, and the broken flange section particularly when a flange is broken, and the broken flange section has been lost.has been lost.

- If denture is broken into several sections, the denture may require a - If denture is broken into several sections, the denture may require a repair, prior to making the impression of the lost flange.repair, prior to making the impression of the lost flange.

- Autopolymerizing resin is painted onto the cast to replace the missing - Autopolymerizing resin is painted onto the cast to replace the missing portion.portion.


Shyn-yuan Lee, and Steven M. Morgano(1995)Described a method of repairing a fractured complete denture

and simultaneously augment the deficient borders and to correct an inadequate posterior palatal seal, correction were

made with modelling compound and an elastomeric impression material.


METHODS TO STRENGTHEN THE METHODS TO STRENGTHEN THE REPAIRED PORTION REPAIRED PORTION

- - Cobalt Chromium Alloy is a material of choice for strengthening Cobalt Chromium Alloy is a material of choice for strengthening denture base. denture base.

- It provides a strong and well-fitting denture base but has certain - It provides a strong and well-fitting denture base but has certain disadvantages:-disadvantages:-

1) Weight – tends to be heavier than those with acrylic base.1) Weight – tends to be heavier than those with acrylic base. 2) Lack of Adjustability – is far less adjustable than acrylic resin. 2) Lack of Adjustability – is far less adjustable than acrylic resin.

- The problem of lack of adjustability and of increased weight can both - The problem of lack of adjustability and of increased weight can both

be minimised by restricting the cobalt-chromium component to a be minimised by restricting the cobalt-chromium component to a horseshoe-shaped palatal strengthener set into the acrylic base.horseshoe-shaped palatal strengthener set into the acrylic base.

- This design results in an impression surface of acrylic resin and thus - This design results in an impression surface of acrylic resin and thus preserves the advantage of adjustability.preserves the advantage of adjustability.


Berry H.H. & Funk O.J. (1971)-Berry H.H. & Funk O.J. (1971)- used vitallium strengthener to prevent lower used vitallium strengthener to prevent lower denture breakagedenture breakage. .

- Design – Had 4 tissue stops touching the crest of theHad 4 tissue stops touching the crest of the

mandibular ridge.mandibular ridge. The tissue stops are 2mm wide and The tissue stops are 2mm wide and

located in the second molar and cuspid located in the second molar and cuspid areas.areas.

The connecting bar measures 4mm wide The connecting bar measures 4mm wide and 1mm thick and is raised and 1mm thick and is raised approximately 1-2mm above the crest of approximately 1-2mm above the crest of the lower ridge. Retention webbing the lower ridge. Retention webbing measures 15mm from the lingual side of measures 15mm from the lingual side of the ridge.the ridge.

- Strengthener is incorporated in acrylic resin - Strengthener is incorporated in acrylic resin and stabilized before packing.and stabilized before packing.www.indiandentalacademy.com

► Badr S.E., Stone C.R. & Unger J.W.(1989)Badr S.E., Stone C.R. & Unger J.W.(1989) – – developed a technique developed a technique of “a metal insert to replace a fractured segment of a mandibular of “a metal insert to replace a fractured segment of a mandibular complete denture.”complete denture.”

- In some patients where surgical reduction is not possible with little - In some patients where surgical reduction is not possible with little space between the retro-molar pad & maxillary tuberosities, dentures space between the retro-molar pad & maxillary tuberosities, dentures are most often made quite thin and as such are prone to fracture.are most often made quite thin and as such are prone to fracture.

Procedure:-Procedure:-

1) Reline impression with polysulphide elastomeric impression material 1) Reline impression with polysulphide elastomeric impression material is made in the denture and cast is poured.is made in the denture and cast is poured.

2) Jaw relations are recorded and facebow-tansfer done to mount the 2) Jaw relations are recorded and facebow-tansfer done to mount the maxillary cast on the articulator.maxillary cast on the articulator.

3) Mount mandibular cast by using the jaw relation record.3) Mount mandibular cast by using the jaw relation record.


4) Remove the fractured portion of the mandibular denture and make a 4) Remove the fractured portion of the mandibular denture and make a pattern in Dura-Lay resin on the cast. Avoid contact with the opposing pattern in Dura-Lay resin on the cast. Avoid contact with the opposing denture.denture.

5) Cut openings in the pattern to retain casting in the denture. Invest the 5) Cut openings in the pattern to retain casting in the denture. Invest the acrylic resin pattern and cast it in metal of choice.acrylic resin pattern and cast it in metal of choice.

6) After polishing the casting,6) After polishing the casting,

incorporate into the final incorporate into the final

wax contour of denture wax contour of denture

base, invest and process.base, invest and process.


A study was done in our college Under The Able Guidance of A study was done in our college Under The Able Guidance of Dr N.P.PATIL(2006) to see the Dr N.P.PATIL(2006) to see the “EFFECT OF JOINT

SURFACE CONTOURS ON THE TRANSVERSE STRENGTH AND IMPACT RESISTANCE Of DENTURE

BASE RESIN REPAIRED BY VARIOUS METHODS”

► Repair was carried out by heat polymerization, autopolymerising resin using pressure pot and autopolymerising resin with glass fibers (with and without treatment with silane coupling agent). Samples were given different joint surface contour namely butt and 450 bevel.

► Transverse and impact strength tests were tested using Instron universal testing machine and Izod impact tester. .

► Glass fiber treatment with silane coupling agent significantly increased the transverse and impact strength of autopolymerising resin.


► For the Impact strength the effect of joint surface contour of butt and 450 bevel is not significant for the groups repaired by heat cure and self cure, while it was significant for the groups reinforced by glass fiber (with and without treatment with silane coupling agent), with 450

bevel joint showing higher strength.

It was concluded that:► ¨ Self cure resin produced the lowest strength after repair.► ¨ Fractured specimen repaired by heat cure method showed 30-40%

higher values of transverse strength as compared to cold cure Groups.► The transverse and impact strength values after repair were highest

with autopolymerising resin with glass fibers after treatment with silane coupling agent, having 450 bevel joint.

► Impact strength was not affected in case of samples repaired by self cure and heat cure, but the strength increased in fiber reinforced Groups with and without silane coupling agent treatment.


PREVENTION OF DENTURE FRACTUREPREVENTION OF DENTURE FRACTURE

1) A good processing technique which reduces or eliminates residual 1) A good processing technique which reduces or eliminates residual stresses within the denture and avoids surface defects.stresses within the denture and avoids surface defects.

2) Using higher strength polymers, impact resistant materials to reduce 2) Using higher strength polymers, impact resistant materials to reduce the tendency of fracture.the tendency of fracture.

3) Constructing dentures with metal plates for patients with heavy 3) Constructing dentures with metal plates for patients with heavy occlusions.occlusions.

- Greater Strength- Greater Strength - Better Thermal Stimulation.- Better Thermal Stimulation. 4) The use of occlusal checks and inserts, help to reduce tooth wear.4) The use of occlusal checks and inserts, help to reduce tooth wear. 5) Avoiding deep incisal spaces and increasing the bulk of base 5) Avoiding deep incisal spaces and increasing the bulk of base

thickness in areas palatal to incisors reduces the possibility of midline thickness in areas palatal to incisors reduces the possibility of midline fracture.fracture.

6) Placing a thin beading around a heavy labial frenum to improve the 6) Placing a thin beading around a heavy labial frenum to improve the seal has strengthening effect and leads to improved stress distribution.seal has strengthening effect and leads to improved stress distribution.


SummarySummary ► Resurfacing and replacement of the denture base of a complete Resurfacing and replacement of the denture base of a complete

denture is complicated procedure requiring astute clinical judgment denture is complicated procedure requiring astute clinical judgment and skill if the therapy is to be successful.and skill if the therapy is to be successful.

► When the denture bases are under-extended, when there has been a When the denture bases are under-extended, when there has been a gross loss in the occlusal vertical dimension , and when centric gross loss in the occlusal vertical dimension , and when centric relation and centric occlusion do not coincide, then fabrication of new relation and centric occlusion do not coincide, then fabrication of new denture would be treatment of choice.denture would be treatment of choice.

► A relined complete denture should be remounted on the articulator A relined complete denture should be remounted on the articulator and the occlusion refined to eliminate occlusal interferences resulting and the occlusion refined to eliminate occlusal interferences resulting from three-dimensional denture displacement during relining. from three-dimensional denture displacement during relining.

► Relined or rebased dentures should be given the same care as new Relined or rebased dentures should be given the same care as new dentures, and the patient should be recalled as often as necessary for dentures, and the patient should be recalled as often as necessary for

examination of the tissues and the jaw relationsexamination of the tissues and the jaw relations..


► Many factors can contribute to the fracture of a complete denture. Many factors can contribute to the fracture of a complete denture. Recognition of these factors and their prevention or correction will Recognition of these factors and their prevention or correction will result in dentures that are physiologically and functionally acceptable result in dentures that are physiologically and functionally acceptable for the patients. for the patients.

► Several methods for repairing dentures with autopolymerizing resin Several methods for repairing dentures with autopolymerizing resin are described. are described.

► Successful denture repairs should provide adequate strength and the Successful denture repairs should provide adequate strength and the minimal distortion to denture.minimal distortion to denture.

Tooth replacement Fractured dentures

Anterior teeth Posterior teeth

Non-separated parts

Separated parts

Missing parts

Denture repairDenture repair


ReferencesReferences Resins in dentistry: DCNA 1975; vol. 19(2): 357-366.Resins in dentistry: DCNA 1975; vol. 19(2): 357-366.Bolouri, Bell J.D. : The use of intraoral cores to repair complete and removable Bolouri, Bell J.D. : The use of intraoral cores to repair complete and removable partial processes. J.P.D. 1976; 36: 472-475.partial processes. J.P.D. 1976; 36: 472-475.Beyli M.S. : Repair of fractured acrylic resin. J.P.D. 1980; 44: 497-503.Beyli M.S. : Repair of fractured acrylic resin. J.P.D. 1980; 44: 497-503.Halperin A.R., Abadi B.J. : Repair of broken denture in resin undercuts. JPD, 1980; Halperin A.R., Abadi B.J. : Repair of broken denture in resin undercuts. JPD, 1980; 44: 224-228.44: 224-228. Linear dimensional change of heat-cured acrylic resin complete dentures after Linear dimensional change of heat-cured acrylic resin complete dentures after reline and rebasereline and rebase Edmond H. N. Pow, T. W. Chow, and Robert K. F. ClarkEdmond H. N. Pow, T. W. Chow, and Robert K. F. Clark (J (J Prosthet Dent 1998;80:238-45.)Prosthet Dent 1998;80:238-45.)Beyli M.S. : An analysis of causes of fracture of acrylic resin dentures. JPD, 1981; Beyli M.S. : An analysis of causes of fracture of acrylic resin dentures. JPD, 1981; 46: 238-241.46: 238-241.David E.H. : Immediate stabilization of a broken maxillary denture. J.P.D. 1983; 50: David E.H. : Immediate stabilization of a broken maxillary denture. J.P.D. 1983; 50: 289-292.289-292.Farmer J.B. : Maxillary denture fracture. JPD 1983; 50: 172-175.Farmer J.B. : Maxillary denture fracture. JPD 1983; 50: 172-175.Schneider R.L.: Diagnosing functional complete denture fractures. JPD 1985; 54: Schneider R.L.: Diagnosing functional complete denture fractures. JPD 1985; 54: 809-813.809-813.Rudd K.D., Morrow M.R. : Dental laboratory procedures, complete dentures. 1st Rudd K.D., Morrow M.R. : Dental laboratory procedures, complete dentures. 1st edition 1986.edition 1986.Stipho H.D. Effectiveness and durability of repaired acrylic resin joints. JPD 1987; Stipho H.D. Effectiveness and durability of repaired acrylic resin joints. JPD 1987; 58: 249-252.58: 249-252.Wilson H.J. : Dental technology and materials for students. 8th Edn, 1987.Wilson H.J. : Dental technology and materials for students. 8th Edn, 1987.www.indiandentalacademy.com

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Relining rebasing and repair of complete denture/ dental courses

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