The Functionally Fixed Restoration

8/14/2019 The Functionally Fixed Restoration

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The Functionally Fixed Restoration: A Third Modality of Treatment

Compendium / Feb. 2002

By Paul J. Berson, DDS

Private Practice

Philadelphia, PA

Abstract: Most dental practitioners as well as their patients prefer to have fixed rather than removable restorations.

However, there are many clinical situations that prohibit the use of the fixed modality. These clinical cases can vary

from simply not having the proper number of healthy teeth and/or implants to the esthetically challenging cases of

high smile lines and severe loss of alveolar support. The approach of using a traditional removable prosthesis in these

situations has always been met with severe compromises. The functionally fixed restoration is a third modality of

treatment that can solve many of the problems of the removable restoration and at the same time provide the same

comfort and success of the fixed prosthesis.

Currently, most restorative dentists use two modalities of treatment (ie, restorations involving implants and/or natural

teeth are either fixed or removable). In some cases, a combination of both types of treatment are used. In the past,

these modalities provided a restoration that fulfilled the expectations of the patients. However, patients' expectations

have now risen. Patients want their teeth to look whiter and feel healthier at all times. They also want their

restorations to last a lifetime and, at the same time, be financially within their budgets.

Using natural teeth and/or implants as abutments, the fixed restoration will most often satisfy the expectations of

patients! However, there are a few clinical situations where this modality of treatment falls short. The fixed modality

will not provide the proper anterior esthetics for individuals who have lost substantial amounts of anterior alveolar

support. Oftentimes, the patient is unwilling to undergo periodontal reconstructive procedures to restore his or her

lost attachment.2-4 Consequently, the fixed restoration must replace the loss of periodontium and teeth with only

tooth-colored prosthesis. This leaves the patient with teeth that appear overly large with an unnatural appearance.

Furthermore, many times when there has been a tremendous loss of the periodontium, the restorations need to

support the patient's lip. Figure 1 shows an individual who has lost a severe amount of alveolar support and has been

restored with a fixed implant-supported prosthesis. Note how the maxillary lip is inverted and a concavity is formed.

The individual has taken on a class III profile, which leads to an older appearance. A fixed prosthesis cannot provide

this profile enhancement. Conversely, Figure 2 shows the same type of case restored with a restoration that supports

the maxillary lip. The individual looks more youthful by maintaining a more natural profile.

Traditionally, the removable prosthesis is used when there are not enough teeth and/or implants to support a fixed

prosthesis or there are financial limitations precluding the use of the fixed modality.5 Most dentists and patients are

unhappy with the removable restoration because of the compromises in stabilty, retention, esthetics, and

maintenance. The most severe deficiencies in these restorations are most likely the need for palatal coverage in the

maxillary arch or a lingual bar on the mandibular.6-8


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The functionally fixed restoration can meet the needs of patients in many clinical situations in which the fixed and/or

removable modalities cannot be used. The functionally fixed restoration can provide the proper esthetics and comfort

for a patient with a lack of severe alveolar support coupled with a high smile line.9 If needed, it can provide profile

enhancement. It can also create palateless restorations when there is not enough natural tooth and/or implant

support for a fixed restoration. The functionally fixed restoration is the ultimate unilateral or bilateral distal extension

prosthesis. With the functionally fixed restoration, there is no need for palatal coverage or a lingual bar and it is

extremely effective in combining implants and natural teeth into one restoration.

The functionally fixed restoration is the perfect solution to salvaging a prosthetic restoration where implants were

previously placed in unrestorable positions. Furthermore, this restoration can mediate the problem of poor implant-to-

crown ratios.

The functionally fixed tooth and tissue replacement restoration with removable ponis bar retained, yet tissue

supported.10 The restoration has a fixed as well as a functionally fixed component (Figure 3). The pontics are

absolutely immobile, and do not rise from tissue resilience, nor depress from the forces of occlusion (Figure 4). The

forces from occlusion are directed perpendicularly and equally to all ridge areas. Only a direct, deliberate, precise

action removes the pontics from the fixed permanent section containing the specialized bar. For all intent and

purposes, the removable section is functionally fixed.11 It acts as a fixed restoration from a phonetic, esthetic, and

masticatory prospective. The only difference between a fixed and a functionally fixed restoration is that with the latter,

the pontics can be removed by the patient for hygienic reasons.

The functionally fixed restoration incorporates the use of Andrews bars and sleeves.12 These attachments can be used

as a single bar and sleeve, as well as a double bar with a corresponding sleeve (Figure 5). The bar is attached to the

fixed fixed prosthesis. These curved bars and sleeves are made of a special stainless-steel material that is mated to

tolerances of 1:2,000 of an inch. They are cut from three different sized concentric rings. The curvature of the bars

and sleeves allows the covered ridge to be under constant pressure from occlusion, as well as provide the retention. A

molecular "stickiness" is created when the two pieces move against each other. Small grooves along the length of the

bar prevents full metal contact, which prohibits the creation of too much retention.

The attachments also allow for a quick increase in retention by crimping the bar very slightly with three-pronged

pliers. The key point is that these restorations are bar-retained, yet tissue-supported.

The sleeve should be set 1 mm above the bar as the acrylic comes into contact with the tissue. The attachment does

not bottom out. The saddle and flange areas aid with the retention of the restoration, as well as help distribute the

occlusal forces over the entire edentulous area. This protects the abutments from undue occlusal pressure.


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Case 1

Case 1 is a 58-year-old woman who lost teeth Nos. 11 through 16. Figure 6A shows an x-ray of the edentulous

maxillary left quadrant with the placement of two implants in the positions of teeth Nos. 11 and 12. Additional

implants were not possible. Note the tremendous loss of alveolar attachment apparatus and, consequently, the large

amount of interarch room between the arches on the working model (Figure 6B). A fixed provisional shows how

unesthetic this restoration would be as a permanent option. All of the areas above the black markings (Figure 6B)

need to be restored with a tissue?colored replacement instead of a tooth-colored material. If not, the teeth would

appear too large in a mesial/distal as well as a gingival/incisal dimension. Pink porcelain will not provide an esthetic

substitute for the gingiva. There is a very compromised crown-to-implant ratio and the angle of the implants was

decidedly buccal (Figure 6C). Teeth Nos. 9 and 10 required full crown coverage for restorative reasons.

The functionally fixed restoration (Figures 6D and 6E) provided the patient with the proper esthetics. Not only are the

teeth in the correct proportions as they relate to other natural dentition, but the restoration allows for cheek support.Also, the restoration allowed three more teeth to be added, which enhanced the patient's smile.

This restoration has many other functional advantages. For example, a cantilever is no longer required. The prosthesis

is restored with soft acrylic teeth, which will be kinder to the transfer of occlusal forces to the implants. The poor

crown-to-implant ratio is mitigated by the support the restoration gains by intimate contact with the ridge and palate.

Lastly, the patient has easy access to the daily hygienic maintenance of the implant abutments (Figure 6F).


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Case 2

Case 2 shows a patient who has a minimal number of remaining teeth. The patient is an 86-year-old man. He has

retained teeth Nos. 2 and 13 through 15 as shown by the radiographs in Figures 7A and 7B. Implants were placed but

did not osseointegrate. Telescopes were placed on all of the remaining teeth. A single mesial Andrews bar was placed

on a crown over the telescope on tooth No. 2 (Figure 7C). A double mesial Andrews bar was connected to a threeunitfixed bridge over the telescopes on teeth Nos. 13 through 15 (Figure 7D). Figure 7E shows the palateless functionally

fixed restoration with the two sleeves, which is seated over the fixed sections (Figure 7F). The normal form and

function of the masticatory system was restored by this restoration (Figure G).


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Case 3

Case 3 is a 17-year-old boy (Figure 8A) who has lost teeth Nos. 8 and 9 as a result of a traumatic blow. He has lost a

great deal of the attachment apparatus and has a moderately high lip line. The size of the space between teeth Nos. 7

and 10 dictates the restoration be restored with some form of a diastema. The teeth will appear too large in alldimensions if a diastema as well as some tissue replacement is not incorporated into the restoration. A fixed

restoration would not be able to produce a natural appearing restoration. Figure 8B shows the natural looking

functionally fixed restoration. The Andrews single bar provides the proper retention (Figure 8C) and allows the area to

be easily periodontally maintained. At the same time, the small functionally fixed overcase allows for proper esthetics,

phonetics, and function. Figure 8D shows the functionally fixed section from the lingual view. Note how well the

removable section blends into the natural dentition.

Case 4


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The unilateral distal extension case can be the most challenging situation for the restorative dentist. Most often, the

case is restored with a palate, attachments that wear out, clasps that are anesthetic, or rest seats that interfere with

the occlusion. The functionallyfixed restoration provides the ultimate solution to this problem.13

Case 4 is a 48-year-old woman who has lost teeth Nos. 1 through 4 (Figure 9A). Her smile line prohibited the use of a

cantilevered restoration. A distal Andrews double?bar attachment was cast to a fixed two?unit splint incorporating

teeth Nos. 5 and 6. The functionally fixed component (Figure 913) fully restored the quadrant.14 Once again, the

prosthesis restored the missing teeth and gingiva in the correct proportions. The removable section (Figure 9C) wasbar-retained and has an abutment preserving ridge support. Teeth Nos. 2 through have been replaced with a

comfortable, easily maintained, esthetic prosthesis.

Discussion

Andrews bars and sleeves have many advantages over other types of removable attachments. For example, the

attachment does not bottom out. This allows the removable section to be tissue-supported but bar-retained. This

prevents the restoration from acting as a cantilever. Consequently, these restorations can be made without lingual

lower bars or maxillary palatal coverage. The restorations come in intimate contact with the tissue at the same time

the attachments are engaging.

The metal-to-metal contact of the attachment prevents the need for much adjustment of the retention. In addition,

there are no plastic parts, which can wear out or break. The adjustment for retention is simply made with the

tweaking of the bar with a three-pronged plier directly in the mouth. There is no need for costly indirect laboratoryprocedures to adjust the retention. Furthermore, the curving of the bars and sleeves allows for further retention and

stablity. Also, the special stainless steel material will never corrode. The three different concentric ring sizes allow for

the proper placement of pontics. In addition, the pontics can be located in the space the teeth had occupied.

Therefore, they will not be impinging on the tongue or the lips which can affect speech patterns.

Conclusion

The functionally fixed restoration should be a part of all restorative dentists' armamentarium. Patients are living

longer and are demanding more from from their dentists. They want fewer compromises with their dentitions than any

time before. The fixed and removable modality of treatments cannot always provide the answer to some of their more

challenging prosthetic cases. The functionally fixed restoration gives the dentists one more alternative in helping fulfill

all our patients growing expectations.

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The Functionally Fixed Restoration

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