Treatment of Congenitally Missing Latera Incisors With Resin Bonded Fixed Partial Dentures

8/9/2019 Treatment of Congenitally Missing Latera Incisors With Resin Bonded Fixed Partial Dentures

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Treatment of Congenitally Missing Lateral Incisors

with Resin-Bonded Fixed Partial Dentures

Corky Willhite, DDS*Mike Bellerino, CDT**Jimmy Eubank, DDS***

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issing lateral incisors is one of the mostcommon congenital dental anomalies. 1–4

New technology and materials offer awide variety of treatment options for the replace-ment of missing teeth in order to improve esthet-

ics and restore function.5

Nevertheless, indicationsand limitations of each system have to be consid-ered and weighed in each case for the selectionof the most adequate treatment.

This article presents clinical steps and labora-tory procedures for the treatment of congenitallymissing lateral incisors with resin-bonded fixedpartial dentures, a traditional approach that isconservative and can provide excellent esthetics if certain guidelines are followed. An innovative ap-proach used to handle the gingival issues and toachieve a natural appearance at the periorestora-tive interface is also presented.

TREATMENT PLANNING

Patients who are missing a lateral incisor oftenhave a removable appliance to replace the miss-ing tooth, at least for a while following orthodon-

tic treatment. Besides orthodontic space closure, 6there are several definitive fixed treatment optionsfor missing lateral incisors:

1. Dental implant and fixed restoration2. Full-coverage fixed partial denture (porcelain-

fused-to-metal [PFM], all-ceramic, or resin-based)

3. Partial-coverage fixed partial denture (metalframework [Maryland bridge], ceramic frame-

work, or fiber-reinforced resin with porcelainveneer[s])

Each of these options has advantages and dis-advantages. Implants may eventually be the rou-tine treatment of choice 7–9; however, a number of contraindications must be considered:

• Medical contraindications• Young age (growth incomplete)

***Private practice, Metairie, Louisiana, USA.***Dental Technician, Trinident Laboratory, Metairie,

Louisiana, USA.***Private practice, Plano, Texas, USA.Reprint requests: Dr Corky Willhite, The Smile Design Cen-ter, 111 Veterans Blvd, Suite 777, Metairie, LA 70005, USA.

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• Unfavorable root proximity and/or root align-ment, especially after orthodontic treatment

• Deficient alveolar ridge requiring significantaugmentation

• Smoking habits

• High occlusal stress• Severe occlusal discrepancies

Traditional PFM bridges are long lasting, butsignificant tooth reduction is necessary for highlyesthetic results. In young patients, pulp size maypreclude sufficient tooth reduction.

All-ceramic and resin-based fixed partial den-tures lack long-term scientific clinical data. Practi-tioners are recommending these options increas-ingly often, yet both have disadvantages. Rigidall-ceramic systems require significant tooth re-duction, at least as much as a PFM. In addition,the required connector dimension is limiting inmany patients. An overbite that is equal to or greater than average or tooth size that is equal toor smaller than average (which is common in pa-tients who are congenitally missing laterals) willoften contraindicate a large connector. Fiber-rein-forced resin-based fixed partial dentures 10 may notrequire extensive tooth preparation, but long-

term follow-up studies are not available. The useof such materials requires placement of a porce-lain veneer on the facial of the pontic, which is avery sensitive technique that significantly in-creases operative time.

A resin-bonded fixed partial denture (Marylandbridge) 11–13 represents a very conservative treat-ment approach. However, many practitioners mayhave reservations about this option due to thehigh incidence of failure. 14 It is also challenging toachieve an excellent shade match to the adjacentnatural teeth serving as abutments, as it is withany single crown. The Maryland bridge compli-cates shade matching even more because of theshade change that generally occurs on the abut-ments at cementation due to the cast-metal lin-gual retainers that impart a gray appearance inthe incisal third. Even if the pontic matches per-fectly at try-in, once it has been luted the resultmay be disappointing. However, when certain

clinical guidelines are followed, the resin-bondedfixed partial denture can be conservative, pre-dictable, practical, and highly esthetic.

CASE PRESENTATION

A 17-year-old healthy female had a congenitallymissing maxillary left lateral incisor (Fig 1). Themaxillary right lateral incisor was slightly under-sized and malformed, although not enough for itto be classified as a peg lateral. Orthodontic treat-ment was complete, and the patient was using aHawley-type retainer with a denture tooth at-tached for the prosthetic replacement of the leftlateral. The patient was unhappy with the appli-ance and wanted a permanently fixed solution.Records were taken, and the diagnosis and treat-ment plan were completed.

Soft Tissue Considerationsin the Pontic Area

Ideal gingival contours are the natural frameworkfor any dental restoration and require special at-

tention. The amount of remaining hard and softtissue dictates subsequent treatment to create anatural appearance. In this case, the edentulousalveolar ridge had a deficiency in the gingival ar-chitecture (Fig 2), and though surgical ridge aug-mentation was the most appropriate procedure,the patient declined it. In cases of moderate ridgedeficiencies or if the patient does not comply witha surgical intervention, an ideal pontic site mightbe developed with a fixed temporary restorationand a pontic specifically shaped for this site. How-ever, during fabrication of a resin-bonded fixedpartial denture, the most viable temporaryrestoration is often a removable appliance. In thepresent case, a thermoformed clear acrylic appli-ance (Essix, Raintree Essix Inc, Metairie, LA, USA)with a denture tooth in the left lateral incisor posi-tion was used as a provisional restoration with anadditional goal of reshaping the underlying gin-giva (Figs 3a and 3b). Since this patient had a gin-


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gival deficiency, it was decided to avoid any gin-givectomy procedure at the pontic receptor siteand rather to guide the soft tissue into a moreideal shape without surgical intervention.

Indications for a nonsurgical gingivoplasty are:

1. Slight-to-moderate horizontal deficiencies2. Slight or no vertical deficiencies3. Gingival thickness over bone of at least 2 mm4. Mesiodistal space available within normal

ranges5. Patient willing to comply with a removable ap-

pliance for a few weeks

The limitations of this technique are primarilyrelated to the lack of new tissue “created,” sincethere is no augmentation of the ridge. Therefore,this technique is not indicated if severe ridge de-fects exist. However, no surgery is needed to cre-ate an ovate pontic receptor site if the patientmeets the aforementioned criteria. This methodalso creates an opportunity to increase the appar-ent size of the papillae, to give the appearance of additional facial bulk of tissue, and to form a gin-gival-tooth interface that resembles that of a nat-ural tooth.

Fig 1 Preoperative view. Maxillary left lateral incisor iscongenitally missing and the maxillary right lateral in-cisor is malformed. Orthodontic treatment is complete.

Fig 2 The edentulous alveolar ridge reveals a deficiencyin the gingival architecture.

Figs 3a and 3b A thermoformed clear acrylic splint (Essix appliance) with a denture tooth in theposition of the left lateral incisor was used as a retainer with an additional goal of “orthodonti-cally” shaping the underlying gingiva.


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Orthodontic Considerations

This particular patient had successfully completedorthodontic treatment. Orthodontic interventionoften is required prior to the restorative treatmentphase to address unfavorable spacing or occlusalissues and to optimize the position of the teeth. 6,7

It is recommended that the restorative dentistevaluate the patient prior to orthodontic treat-

ment and close to its completion. Information onthe restorative treatment may influence the or-thodontic result, and in some cases, minor modifi-cations prior to the removal of the brackets willimprove the restorative result.

Restorative Treatment

Since the patient was not satisfied with the origi-nal shade of her natural teeth, home bleachingwas performed until she was satisfied with theshade. A direct composite restoration was thenfabricated to improve the shape of the small, mis-shapen right lateral incisor. During the operativeprocedure it is important to keep in mind that theplanned pontic must mimic the contours of the re-stored right lateral incisor. Reasonable symmetrywas a goal for achieving an overall esthetic smile(Figs 4a and 4b).

Temporary Restoration and Soft TissueContouring

An Essix appliance adapted to the six anterior teeth was fabricated to replace the Hawley re-tainer. A denture tooth was used as a pontic to re-place the left lateral incisor, which provided acomfortable and esthetic provisional without theuse of a wire and the bulkiness of the previous re-

tainer. This denture tooth was selected in the ap-propriate shade and mold, and was then cus-tomized to resemble the contralateral tooth. Insimilar cases, microetching the denture tooth,using an unfilled resin as an adhesive, and addinga hybrid composite may accomplish further modi-fications. The tissue side of the pontic was con-toured in a ridge-lap shape to avoid initial imping-ing of the tissue. Proper alignment of the denturetooth to the approximating teeth was verified, andthe denture tooth was attached to the modelusing light-cured block-out resin. This resin waspreferred over sticky wax to avoid any materialthat would melt during adaptation of the thermo-formed Essix material. Essix Type B and C+ arethe materials of choice due to their optimal es-thetic and physical properties and excellent dura-bility. After removal of the thermoformed plasticfrom the model and subsequent trimming, thedenture tooth was separated from the model and

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Figs 4a and 4b Situation after home bleaching and operative restoration of the misshapen rightlateral incisor with a direct composite restoration. Keep in mind that the planned pontic mustmimic the contours of the restored right lateral incisor.


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slipped into the Essix. To ensure adequate reten-tion, Triad gel (clear) (Dentsply, York, PA, USA) wasapplied into the pontic space of the Essix appli-ance. The denture tooth was repositioned, excessgel was removed, and the restoration was light-

cured. This type of appliance is approximately 0.5mm thick, which the patient quickly adapted to.However, a minimally open bite has to be ex-pected in the anterior region if the appliance isworn full time, but the open bite is reversedwithin a few weeks of discontinuing the use of thisappliance. 16

Shaping of the pontic receptor site was started1 week after the patient received the Essix appli-ance to allow for adaptation. Initially, a narrow ex-tension—the “site former”— was added to thebase of the pontic (Figs 5a and 5b). The apical as-pect of the denture tooth was microetched andrinsed. An unfilled resin was applied and addi-tional composite sculpted to the desired shape.This initial shape was modified every few days toguide the tissue primarily toward the facial aspect.Local anesthesia was administered to assure pa-tient comfort when the appliance was first placedin the mouth, which can be avoided with a more

gradual addition of composite. The patient wasinstructed to remove the appliance for cleaningonly and to replace it within a few minutes inorder to avoid tissue relapse. Additional compos-ite was gradually added twice a week in small in-

crements without the need for anesthesia. After 6weeks, the natural tooth pontic receptor site hadreached the desired shape (Figs 6a to 6c).

Final Preparation

The preparation design used was similar to aMaryland bridge using a PFM pontic fixed withcast-metal lingual retainers adhesively cementedto the adjacent abutment teeth. Contrary to thetraditional Maryland bridge technique, the abut-ment teeth were prepared on the lingual aspectto avoid extension of the metal framework ontothe thinner incisal third to half of the abutmentteeth, which would compromise esthetics. To in-crease retention and to prevent a bulky frame-work, a definitive preparation (Fig 7) with nearlyparallel walls, sharp internal line angles, and a pinhole (about the size of a 330 bur) centered in the

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5a 5b

Figs 5a and 5b After about 1 weekof wearing the Essix appliance, anarrow extension made of compos-ite—the “site former”—was addedto the base of the pontic.

Figs 6a to 6c After adding incre-

ments of composite twice a week for a total of 6 weeks, the pontic recep-tor site had reached its desiredshape.

6a 6b 6c


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cingulum area was fabricated. Little or no diespacer is used on the master cast for accurateadaptation of the cast metal to the preparation(Fig 8). The combination of accurate fit, retentivepreparation design, adequate pretreatment of themetal surfaces, and a composite resin luting mate-rial should increase the long-term retention of a

resin-bonded fixed partial denture.

Fabrication of the Final Restoration

The Essix appliance continued to be used for atemporary restoration during fabrication of thefinal restoration in the dental laboratory. The metalframework was waxed up, cast with an alloy con-taining 74% Ni and 13% Cr (Williams Pisces,Ivoclar Vivadent, Amherst, NY, USA) (Fig 9) andcoated with Deck-Gold (Degussa, Bloomfield, CT,USA) (Fig 10). The framework was tried in during aseparate appointment and, after verification of op-timal fit, sent to the laboratory where the veneer-ing porcelain was built up and fired (Figs 11 to 16).Figure 17 shows the final restoration. The tissueside of the ovate pontic was contoured to placeslight pressure on the gingiva at delivery in order to assure a tightly adapted tissue surface and ade-

quate support of the interproximal papillae andthe “generated” facial tissue. The tissue shouldblanch with initial placement and return to normalcolor within a few minutes. Proper interocclusalcontacts in static and dynamic occlusion were veri-fied. The oral surfaces of the metal frameworkwere covered with a thin layer of porcelain to

achieve a toothlike shade. With resin-bondedbridges, the weak link in the metal-composite-tooth unity is usually the metal-composite inter-face. Therefore, selection of an adequate alloy andpretreatment of the metal surface are key factorsfor the long-term survival of resin-bonded fixedpartial dentures. Nonprecious alloys should beused due to their rigidity and ability to build anoxide surface layer, which facilitates resin bonding.

Various surface treatment methods are available toenhance the micromechanical and chemical bondof resin cements to the metal surface. 15 The metalbonding surface was acid etched in the dental lab-oratory and air-abraded with a micro-sandblaster (Microetcher ERC, Danville Engineering, SanRamon, CA, USA) in the dental office. Final cemen-tation was accomplished with an opaque, autocur-ing resin cement (Panavia 21 opaque, Kuraray,Osaka, Japan). Figure 18 shows the 2.5-year fol-low-up of the completed restoration.

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Fig 7 Intraoral view of the final preparations of theabutment teeth (the maxillary left canine and central in-cisor) for a resin-bonded fixed partial denture.

Fig 8 Little or no die spacer on the master cast allowsfor the most accurate adaptation of the cast metal to thepreparation.


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Figs 9a and 9b Cast framework, lingual and buccal views.

Figs 10a and 10b Framework after coating with Deck-Gold (Degussa), lingual and buccalviews.

Figs 13a and 13b Translucent layering, lingual and buccal views.

Fig 11 Opaqued framework, lingual view. Fig 12 Dentin buildup, lingual view.


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Figs 17a and 17b Completed prosthesis, lingual and buccal views.

Fig 14 Prosthesis after first firing cycle, lin-gual view.

Fig 15 Cervical buildup with saturateddentin and internal characterization of thebuccal surface.

Figs 16a and 16b Completed buildup of the translucent enamel, lingual and buccal views.


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CONCLUSION

Though a variety of options are available to solvethe problem of congenitally missing lateral in-cisors, this article presented a modification of atraditional technique. Long-term success of resin-bonded fixed partial dentures depends on thepreparation design, fit, metal and tooth-surfacepretreatment, and luting agent. In addition, the

nonsurgical gingivoplasty created a pontic recep-tor site almost as ideal as with surgical augmenta-tion. This modified technique may satisfy the func-tional and esthetic demands of today’s patients. Itis a minimally invasive and very conservative treat-ment approach. However, certain clinical guide-lines and laboratory steps have to be followedclosely, and controlled clinical trials are necessaryto verify its long-term success.

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Figs 18a to 18c Postoperative (2.5-year follow-up) views: contralateral side, radio-graph, and resin-bonded fixed partial den-ture replacing the maxillary left lateral in-cisor.


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Treatment of Congenitally Missing Latera Incisors With Resin Bonded Fixed Partial Dentures

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