The Bridgeless Bridge: A Real World Solution to a Common Problem

INTRODUCTION
Practicing in the “age of adhesive dentistry” allows clinicians to be more creative than ever. Sometimes, we can find minimally invasive solutions that solve problems we regularly face while not having to put our patients through lots of treatment that they don’t want.

This article will describe a method of replacing a lost first molar in an adult when the space has partially closed due to mesial drifting/tilting of the second and/or third molar. The patients discussed below chose not to undergo orthodontic uprighting, conventional crown and bridge procedures, or implant replacement. In both of these cases, we replaced the missing first molar with, for want of a better name, a “bridgeless bridge (BB).”

Figure 1. Illustration of ideal versus malposed molar and effect on occlusal plane.

Figure 2. (Case 1) Preoperative lateral view.	Figure 3. Preoperative occlusal view.
Figure 4. Old amalgams removed, and glass ionomer liner placed, etched, washed and dried.	Figure 5. Proximal addition, facial view.
Figure 6. Proximal additions, occlusal view.	Figure 7. Curing composite resin through thin clear plastic (Saran Wrap).
Figure 8. Occlusal view of direct resin onlay completed on molar.	Figure 9. Facial view of direct resin onlay completed on molar.

Figure 10. Bicuspid onlay in progress.

When a lower first molar is lost early in life and not replaced, several things may happen. In addition to mesial drifting/tilting of teeth distal to the space, there can be distal drifting, tilting, and rotation of the bicuspids (Figures 1 and 2). Opposing upper teeth may extrude and disrupt an ideal occlusal plane. In some cases, periodontal structures of the malposed lower teeth will become compromised because of occlusal hypofunction^1,2 and masticatory forces being misdirected from the vertical axes of these teeth. Additionally, skeletal and dental asymmetries may develop, especially in the lower third of the face from the early first molar loss and nonreplacement.³ A treatment plan might include orthodontics to upright and/or reposition the teeth adjacent to the compromised space. If second and third molars are present, and the third molar is deemed unnecessary, it could be removed and orthodontics done to upright the remaining second molar. Conventional bridgework or an implant might be considered after appropriate space was regained.

Some clinicians may opt not to regain the lost space and place a conventional 3-unit bridge with a “mini-pontic.” If the anticipated path of insertion of the bridge is problematic, a telescope coping could be placed on the malpositioned second molar followed by the placement of a 3-unit bridge. Another possibility would be to recontour the interproximal surfaces of the teeth adjacent to the space and to place a resin-bonded bridge. For some patients, a clinician might accept an occlusion that ends at the second bicuspid, depending on what teeth are present in the opposing arch.

What is the BB and what are some of its advantages? The BB is actually 2 individual overbuilt onlays placed on the teeth adjacent to the compromised space. There are many advantages to the BB: it is patient friendly, restores occlusion, is minimally invasive, and can be completed in a single visit (and if done indirectly, in 2 visits). Finally, all other treatment options still remain, and could be performed at a later date if desired or necessary.

CASE 1: DIRECT COMP
It was 1986, and what we were faced with is illustrated in Figures 1 to 3.

Diagnosis and Treatment Planning
After careful evaluation (dental, social, and financial considerations), overbuilt bonded direct resin restorations were chosen. The treatment plan called for onlays to build new occlusal surfaces, and to also build out the proximal surfaces to contact each other, thereby closing the space. Because this patient had demonstrated excellent reliability in coming in for periodic reexamination and maintenance visits, we would be able to monitor the restorations and the periodontal status of the restored teeth. If a periodontal problem developed at a later time, we could remove the resin composite restorations in one short visit and choose another method to solve the problem.

Clinical Technique
The patient was anesthetized and the old amalgam restorations on the occlusal surfaces of her second molar and second bicuspid were removed. A glass ionomer lining was placed. Phosphoric acid-etching, followed by washing and drying, was completed (Figure 4). (Note: Enamel etching was extended past the proximofacial and proximolingual line angles in addition to the entire occlusal surfaces and cavity preparations.)

Figure 11. Bicuspid onlay completed; new contact area.	Figure 12. Bridgeless bridge, immediately post-op.
Figure 13. (Case 1) Postoperative photo at 26 years, prior to recall visit (May 31, 2012).	Figure 14. (Case 1) Occlusal view prior to maintenance visit (May 31, 2012).
Figure 15. (Case 1) Occluso-lingual view prior to maintenance visit (May 31, 2012).	Figure 16. (Case 1) Radiograph taken before prophylaxis (August 9, 2012).

A bonding agent was applied and light-cured. Beginning with the mesial of the second molar, increments of composite resin (Herculite [Kerr]) were added in a gingivo-occlusal direction and slightly overbuilt to the facial and lingual. This allowed for the slight reduction expected during the contouring and polishing steps (Figures 5 and 6). These proximal additions were shaped with an IPC carver (Premier Dental Products); these would ultimately occupy one half of the gap between the second molar and second bicuspid.

As the mesial marginal ridge was approached, the previously lined cavity preparations were filled. Composite resin was added to the occlusal aspect, with some excess being placed on purpose. Clear thin plastic (Saran Wrap) was placed over the uncured composite, and then the patient was asked to close and open her teeth several times, grinding her teeth in function in all directions. This allowed the patient’s existing dentition and excursive movements to develop functional occlusal anatomy. With the patient still closed on the clear plastic, the resin was light-cured first from the facial, then, after the patient opened, from the lingual and occlusal aspects (Figure 7).

The occlusal anatomy and new proximal contour were refined and polished. The proximal additions were checked with dental floss to be sure they were smooth from gingival to occlusal. Figures 8 and 9 illustrate the completed addition on the second molar. The same procedures were followed for onlaying the bicuspid (Figure 10).

No matrix strip was used between the previously polished molar onlay and the bicuspid addition so a tight contact area could be formed. Since the newly formed mesial surface of the second molar was highly polished, there would be no chemical bond between it and the proximal addition to the bicuspid. By placing a plastic instrument into the newly formed gingival embrasure and gently torquing the instrument, approximating resin surfaces were easily separated. (This is a technique learned from Dr. “Buddy” Mopper, hence the name “Mopper Torque.”) So as not to alarm the patient when the mechanical force was applied, she was informed that there would be a slight “cracking” sound. The occlusion was checked and the final result of this BB is seen in Figures 11 and 12. The patient was shown how to clean between the onlay restorations using floss and a Proxabrush (Butler).
Because she was pleased with the result and a similar problem existed on the opposite side, the patient asked that we use the same technique to restore that area too. Although one might consider this a stretch of an adhesive-resin technique, it is now more than 26 years later and the bridges are still in place and functioning for this patient (Figures 13 to 15). A very healthy periodontium surrounds all the onlayed teeth (Figure 16). The only maintenance required has been an occasional renewal of the marginal areas from stain that could not be polished away and addition of composite resin onto the occlusals as the older composite wore away.

CASE 2: INDIRECT COMPOSITE RESIN TECHNIQUE

Background
A nonconventional dental polymer (Artglass [Heraeus Kulzer]) was introduced in 1995. It was the first product in a long line of a new family of indirect (lab-fabricated) composite resin materials. Since then, this group has expanded with many products. Some other names you may recognize, to name just a few, are belleGlass (Kerr Lab), Concept (Ivoclar Vivadent), Cristobal+ (DENTSPLY Ceramco), Sculpture (Pentron Clinical), and Sinfony (3M ESPE). Improvements are ongoing and more recent additions to this group are Concept HP (Ivoclar Vivadent), Tescera ATL (BISCO), belleGlass NG (Kerr Lab), Gradia Lab (GC America), and Sculpture Plus (Pentron Clinical).

In the mid 1990s, articles and studies about the benefits of these materials as inlays or onlays began appearing. One article stated that this family of materials “combines the positive attributes of indirect composite restorations, feldspathic ceramics, and cast-gold restorations.”⁴ Another article said, “The material is purported to be equal to or better (when indicated) than porcelain for aesthetic dentistry. The strength, color translucency, and color vitality allow minimal destruction of enamel for aesthetics. An artglass occlusal surface is less abrasive to enamel than porcelain, approximating gold.”⁵

Prior to the appearance of these materials, I hesitated to use porcelain for a BB for 2 main reasons. Conventional porcelains tend to be very abrasive to opposing teeth and do not have good fracture resistance. Since cases like these required unsupported restorative material, porcelain did not seem like the right choice. My hope was that the indirect approach would prove viable with this new class of materials and would provide a better patient service than using direct composite resin restorations.
I thought it was time to try one of these new materials in a situation similar to the patient in case 1.

Figure 17. (Case 2) Facial view at 16 years postoperatively.	Figure 18. (Case 2) Occlusal view at 16 years later.

Figure 19. (Case 2) Radiograph taken before prophylaxis (August 9, 2012).

Brief Clinical and Laboratory Synopsis
In January 1996, I sent diagnostic models of this new case to several dental laboratory technicians I respected and asked their opinions on preparation designs. To my surprise, there was no real consensus on how teeth should be prepared for these newer materials. One technician said to prep the teeth the same as for gold onlays. Another said we needed more tooth reduction than usually required for gold. It became apparent we were in unexplored territory.

In the end, I decided upon taking a conservative approach and would keep the preparations minimal.

After the preparations were completed, vinyl polysiloxane impressions (Imprint II [3M ESPE]) and bite registration were taken and sent to the dental laboratory team along with detailed instructions defining our treatment goal. A shade that did not match the teeth was purposely selected (with the patient’s approval) so I could better monitor the margins over time. The restorations were bonded in place and, along with the patient’s periodontal status, they have been monitored since placement.

Advantages and disadvantages to the indirect method became apparent. While function of the indirect restorations has been satisfactory, cement margins appear to have stained more than the margins of the bonded direct composite resin restorations (Figures 17 and 18). However, the occlusal surfaces of the indirect material wore less and maintained anatomy better than those of the direct restorations. It should also be noted that all physical properties (including aesthetics, wear, and gloss retention) have been improved in the newer polymer glasses introduced after this case was completed. One main advantage with the indirect approach is less operator fatigue since indirects are fabricated by the dental laboratory team. Of course, this can also be viewed as a disadvantage since an additional visit is necessary.

Our patient maintained a regular recall schedule and has excellent oral hygiene habits. The periodontal status of the restored teeth can be seen in a radiograph taken prior to her prophylaxis on August 9, 2012 (Figure 19); it confirmed excellent bone levels and a lack of periodontal pocketing.

CLOSING COMMENTS
Now that sufficient postoperative time has passed, it is the author’s opinion that the BB is a viable treatment alternative for some patients who do not want to have, or cannot agree to, other options. However, the clinician must carefully select cases for this treatment option before offering it. A patient’s reliability in keeping recall visits, so that the restorations and periodontal status can be monitored, is critical. Whether to use a direct or indirect technique is another decision to be weighed carefully. Having sufficient knowledge of the different materials available may require a treatment planning consultation with the laboratory team when the indirect approach is considered. Further, choosing a dental laboratory team that has the ability to create restorations with aesthetic and functional excellence is paramount.

There is no ideal one-size-fits-all restorative system. Progress in adhesive technology and materials allows us to continually explore new approaches to treating challenging situations. The early loss and nonreplacement of a permanent first molar is one of those situations. Whether you choose a direct or indirect approach, my hope is that this article has served to broaden your scope of restorative alternatives. When indicated, maybe a BB technique, as outlined above, will be a possible treatment option to consider.

References

1. Kaneko S, Ohashi K, Soma K, et al. Occlusal hypofunction causes changes of proteoglycan content in the rat periodontal ligament. J Periodontal Res. 2001;36:9-17.
2. Walker CG, Ito Y, Dangaria S, et al. RANKL, osteopontin, and osteoclast homeostasis in a hyperocclusion mouse model. Eur J Oral Sci. 2008;116:312-318.
3. Cağlaroğlu M, Kilic N, Erdem A. Effects of early unilateral first molar extraction on skeletal asymmetry. Am J Orthod Dentofacial Orthop. 2008;134:270-275.
4. Koczarski MJ. Utilization of ceromer inlays/onlays for replacement of amalgam restorations. Pract Periodontics Aesthet Dent. 1998;10:405-412.
5. Pensler AV, Bertolotti RL, Miller D. Building laminate veneers and fixed bridges with polymer glass technology. Compend Contin Educ Dent. 1997;18:712-716,718.

Dr. Fier is a full-time practicing clinician, lecturing internationally on aesthetic and restorative dentistry. He is the executive vice president of the American Society for Dental Aesthetics (ASDA), and is a Diplomate of the American Board of Aesthetic Dentistry, a fellow of the ASDA, the American and International Colleges of Dentists, the Academy for Dental-Facial Esthetics, and the Academy of Dentistry International. Dr. Fier has been a consultant to the ADA on patient education materials, and has appeared on cable TV’s series Feeling Good. He has served as an adjunct professor at the dental schools of New York University, University of California at Los Angeles, University of Minnesota, and Loma Linda University, and is a contributing editor for Reality and Dentistry Today. For the past 12 years, he has been listed in Dentistry Today’s annual list of Leaders in Continuing Education. He can be reached at (845) 354-4300 or at docmarv@optonline.net.

Disclosure: Dr. Fier occasionally receives material and lecture support from Premier Dental Products, Kerr, DENTSPLY, 3M ESPE, BISCO, and GC America.