The Functionally Fixed Restoration:
The Answer to the Implatn Aesthetically Challenged Case

Implant News & Views
May/June 2001

By Paul J. Berson, DDS

Often, the restorative dentist is faced with the following dilemma. Should I make this case fixed or removable? You might say there is no dilemma! Whenever possible, make the case fixed. The patient and the dentist will be much happier. However, there are several instances where the choice of a fixed restoration creates an anaesthetic compromise, leaving the patient feeling disfigured. On the other hand, a removable restoration may fully satisfy the aesthetic demands of the situation, but at the same time, it leaves the patient in a compromised functional state. I'd like to introduce an alternative restorative concept, the Functionally Fixed Restoration, which will provide the patient with neither an aesthetic nor functional compromise.

The functionally fixed restoration has a fixed [fig. 1A], as well as, a functionally fixed component [fig. 1B]. The restoration is bar retained, yet tissue supported. The pontics are absolutely immobile, and do not rise from tissue resilience nor depress from the forces of occlusion [fig. 2]. The forces from occlusion are directed perpendicular 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. It acts as a fixed restoration from a phonetic, aesthetic, and masticatory prospective. The only difference is, the patient for hygienic reasons can remove the pontics. There are three types of cases where the aesthetics of the functionally fixed restoration has many advantages over the other two more traditional modalities -fixed and removable.

Tissue Loss

A high smile or lip line, coupled with the loss of teeth and severe loss of tissue presents obvious aesthetic problems for the restorative dentist. Often, implants are placed in areas where there has been a tremendous loss of alveolar support. Many times the implant surgeon is unable to recreate the lost attachment apparatus prior to the placement of implants. Either he may not have the skill, or at the same time, the patient who is willing to undergo implant therapy may be unwilling to go through the added necessary reconstructive procedures to create the proper amount of gingival tissue. Therefore, the aesthetic environment for the restoration has been severely compromised.

Consequently, the dentist has to construct a restoration that not only must replace the missing teeth, but the loss of tissue as welt. A fixed restoration, particularly on a patient with the high lip line, does not provide the proper aesthetic replacement [figs. 3 - 4]. Pink shaded porcelain does not mimic lost tissue. Oversized teeth in a mesial?distal occlusal?gingival dimension wilt not compensate for lack of gingival interproximal tissue. The patient will be left with an unaesthetic smile, filled with large oversized teeth.

Profile Enhancement

In the same vein, particularly on elder patients, the loss of teeth coupled with the severe loss of tissue, may necessitate the need for facial profile enhancement. A fixed restoration will not restore a patient's profile [fig 5]. Often, the fixed restoration makes the patient look older than they really are. Their maxillary lip looks concave and often puts the patient's lower lip ahead of the upper, thus creating a Class III profile. In order for a restoration to be aesthetic in this environment, it must be able to restore the loss of tissue, as well as the loss of teeth, and at the same time, support the maxillary lip.

Implant Position

The third scenario, which imposes aesthetic challenges for the dentist, occurs when implants are poorly positioned. The unsatisfactory position of implants can occur for many reasons. The reasons are immaterial to the dentist or to the patient. The implant is osseointegrated and it must be restored [fig. 6]. In this environment the fixed implant restoration will be unaesthetic, uncleansable and have a poor crown to implant ratio. At the same time, this restoration will produce non?axis occlusal loading, which may be detrimental to the overall longevity of the implants. The functionally fixed restoration may not only be the perfect solution to this situation; it may be the only solution to the problem.

The functionally fixed restoration uses Andrews bars and sleeves. These attachments can be used as a single bar and sleeve [fig. 7A], as well as a double bar and corresponding sleeve [fig. 7B]. These curved bars and sleeves are made of a special stainless steel material that is mated to tolerances of 1/2000th 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 even pressure from occlusion. A molecular "stickiness" is created when the two pieces move against each other. Small grooves along the length of the bar prevent full metal contact, which prohibits creating too much retention. It also allows for a quick increase in retention by crimping the bar ever so slightly with a three prong pliers. These attachments have been in use for thirty years with natural teeth and thirteen with implants.

Once again, these restorations are bar retained yet tissue supported. The sleeve is set one mm above the bar as the acrylic comes into intimate contact with the tissue. The attachment does not bottom out [fig. 8]. 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 and protect the implants from undue occlusal pressure.

Case Study

This article will only deal with the first type of aesthetic challenge. Figure 9 is an x-ray of two implants replacing teeth #11 and #12. It was not possible to place any more implants distal to this area. Teeth #9 and #10 are needed to receive full crown coverage for restorative reasons [fig. 10].

The question becomes, "Should the quadrant be restored fixed or functionally fixed?" The patient has lost an extreme amount of alveolar support [fig. 11]. In order for this restoration to be aesthetically acceptable, the area marked in black on the provisional must be restored as a gingival replacement [fig. 12]. If the loss of tissue is replaced with only a tooth colored restoration, then the teeth will appear abnormally large as compared to the rest of the arch. Figure 13 demonstrates the unaesthetic provisional.

Comparison

To make a point, I restored this quadrant both ways. Figure 14 shows the conventionally way of restoring this quadrant. Teeth #9 and 10 have splinted porcelain to metal crowns. Teeth #11, 12, and 13 (a cantilever) are restored with a fixed porcelain splint. The crowns are cemented over two custom abutments [fig. 15], which are screwed into the implants [fig. 16]. Pink porcelain is added to the gingival of the crowns in an attempt to mask the loss of alveolar support. Obviously, these crowns are much larger, in the occlusal?gingival, as well as in the mesial?distal dimensions, than her natural teeth [fig. 17]. Furthermore, one might question the occlusal forces that are now placed on this restoration. Not only is there the added concern of a cantilever, but also the crown to implant ratio is considerably compromised.

Advantages

On the other hand, the functionally fixed restoration restores the quadrant to a more natural appearance [fig. 18]. The inclusion of pink acrylic allows the restored teeth to be of natural size. The functionally fixed restoration allows for the replacement of two more teeth than the conventional splint, and at the same time offers more protection to the implants from the forces of occlusion. The forces of occlusion are spread over the entire soft tissue of the quadrant by the removable section, which is in intimate contact with the gingival surfaces. The acrylic teeth of the pontics will wear more easily than porcelain teeth. This will further protect the implants, particularly if the patient suffers from occlusal parafunctional habits.

Oral Hygiene

In addition, the functionally fixed restoration can easily be maintained. Once the pontics are removed, the patient has total access to the abut ments for daily cleaning [figs. 19 -20]. Figure 21 is an x-ray of the fixed portion of the functionally fixed restoration. Figures 22 and 23 show the final functionally fixed prosthesis.

Satisfied Patient

The patient who has become severely deformed through the loss of attachment apparatus presents many challenges to the implant surgeon as well as the restorative dentist. Often times, the fixed implant restoration is not able to satisfy all the aesthetic and functional needs that this type of patient may require. The functionally fixed restoration will give the dentist a better chance to satisfy what the patient "really" wants from their dentistry. The patients simply want to look fabulous, feel great, and want their dentistry to last a long time.

References

1. Figure 1 courtesy of Dr. Jim Andrews, Institute of Cosmetic Dentistry.
2. Andrews, "A Unilateral, Free-end, Saddle Bridge", Dentistry Today 1998 17(4):120-121.
3. Starr and Miller, "Implant Placement in the Vertically Enhanced Ridge-A Surgical and Restorative Interdisciplinary Approach", Compendium 2001,22 (1):13.
4. Andrews, "The Andrews Bar-and Sleeve-Retained Bridge: A Clinical Report" Dentistry Today 1999, 18 (4):94-99.
5. Dental Laboratory personal communication Mr. William Berenato, Cherry Hill, N.J.

Paul J. Berson, DDS

has been practicing clinical prosthetic dentristy in Villanova, Pennsylvania for 25 years. He is an Assistant Clinical Professor of Restorative Dentistry at the University of Pennsylvania of Dental Medicine. Paul is on the Board of Directors and contributor to the internet continuing education web site www.Dentrek.com. He can be readed at (215) 567-0800 or by fax at (215) 567-6244.