Written by Kenneth M. Hamlett, DDS Monday, 31 July 2006 19:00
In cosmetic dentistry, things aren't always what they seem at first glance. Performing a thorough evaluation to fully analyze each patient's unique case is essential, because you never know what you will find. Such was the case with a 38-year-old man who recently came in looking for replacement of old restorative work and a brighter, more attractive smile (Figures 1 and 2).
The case seemed fairly straightforward. He presented with 2 maxillary anterior bridges from cuspid to central, congenitally missing laterals, and a lower anterior bridge that was attached to some retained deciduous teeth and to cuspid abutments. When he closed his mouth, he hit on the back teeth, and his anterior bite was open approximately 2 mm. Neither the patient nor his previous dentist believed his bite was unusual or unnatural. The dentist had restored the teeth about 12 years earlier to the current bite, and the patient felt no pain and never complained.
Figure 1. "Before" smile.
|Figure 2. Centric occlusion, retracted.|
|Figure 3. Centric relation retracted.|
Indeed, we would not have discovered a problem without performing bimanual manipulation in the style of Dawson and Pankey, which fortunately we had incorporated as a regular part of our diagnostic routine. As we uncovered the uniquely challenging aspect of the case, the information revealed a dramatic disparity between the patient's current centric occlusion and his centric relation-where the correct bite should be. Apparently, when the patient was young he began to stretch his joints and ligaments to jump the high spots on the teeth and close his front teeth down. Over time it became second nature, and he was now entirely comfortable with the acquired bite. After the manipulation, his occlusal scheme changed dramatically; he closed only on his third molars, and his anterior bite opened to about 5 mm rather than 2 mm. Since his current dislocated jaw might cause pain, calcification, and other problems as he aged, the real treatment challenge was this: restoring the jaw to its centric relation while closing the bite down to create a beautiful and comfortable smile (Figure 3).
ADJUSTING THE BITE
We discussed the results of our analysis with the patient and documented the results of our bimanual manipulation with photographs, a face-bow, bites, and impressions. Using the records, we mounted the occlusal scheme on an Artex articulator (Jensen). This replicated the jaw movements and allowed us to discover the occlusal prematurities. At this point we settled on a tentative treatment plan: performing occlusal equilibration to correct the patientÌs bite and finishing the bite with bridges and 12 veneers in the upper arch, and bridges and 10 veneers in the lower arch. We wanted an all-ceramic solution and selected MACVeneers by MicroDental Laboratories and zirconium-based Micro-Dental bridges for the lifelike beauty and strength of MicroDental porcelain. The porcelain strength was especially important because closing the bite would require slightly longer teeth.
Figure 4. Centric relation-centric occlusion after equilibration.
We tested the occlusal equilibration on the articulator to see if we could correct the occlusion, and once satisfied, replicated the process in the patientÌs mouth. We then used a T-Scan II by Tekscan to enable computerized bite registration analysis and identify the occlusal discrepancies (Figure 4). The computer allowed us to fine-tune the occlusal scheme, eliminate movement in the joints and jaw, and produce a solid, stable, comfortable bite for the patient. We were quite pleased with the results and proceeded to prepare the teeth for restoration.
|Figure 5. Upper right preparation with Blu-Mousse (Parkell) inside Sil-Tech for establishing vertical and occlusion.||
Figure 6. Blu-Mousse inside Sil-Tech for establishing vertical and occlusion after upper left preparation.
For the maxillary arch, we first prepared 2 bicuspids and a molar on the right, took a bite registration (Figure 5), and then repeated the procedure on the left. We removed the old bridges in front, recontoured the tissue with a Biolase laser, finished preparing the maxillary anterior teeth, and took a bite registration.
For the mandibular arch, we started by preparing 3 teeth on the right side. We discarded the original bite on the right side, used the old or previous bite for the left, and kept the old anterior bite, producing a tripod effect. Next we prepared 3 teeth on the lower left and discarded the left bite. Then, we placed the right bite we had created after preparing the right side (Figure 6), and again used the old anterior bite. The patient bit down and made a new bite registration for the left side. The procedure left us with 2 new bites and the original anterior bite.
Our preparation of the lower anterior was complicated when we discovered the loose and mobile condition of the deciduous teeth after removing the old anterior bridge. We considered abandoning our earlier plan and placing implants instead of a new bridge. However, since no stable teeth were preserving the ridge, removing the old bridge left a knife-edge ridge with a buccal-lingual distance that was very small. We advised the patient that creating a suitable ridge for implants would require considerable grafting and surgery. Ultimately, he preferred to avoid the hassle, time, and expense. Since the bicuspids were already prepared, the patient opted for a bridge. We placed the new upper bites within the Sil-Tech stint (Ivoclar Vivadent), also with the new lower left and right bites in the stint creating the final bite (Figure 6).
TEMPORARIES AND FINAL RESTORATIONS
|Figure 7. Temporaries positioning Expasyl.||
Figure 8. Luxatemp temporaries.
Figure 9. "After" smile.
Figure 10. Retracted "after"smile.
At this point, all new bites were created. We then took a stick bite and did a face-bow on the preparation. The laboratory had previously created a wax-up and a stent, used to produce and place B1 Luxa-temp (Zenith/DMG) temporaries. Expasyl (Kerr) was placed, and impressions taken. The temporaries were used to further enhance the abilities of the Expasyl for retraction (Figure 7). The temporaries functioned as prototypes of the final restorations (Figure 8) and gave us an exact sense of how things would look and what needed to be altered (eg, the occlusion; the size, shape, color, and length of the teeth; the effect on speech, etc). After making adjustments, we took photographs and impressions and sent them to MicroDental Laboratories, which used the visual information to create veneers and bridges for the upper and lower arches.
The patient returned about 2 weeks later. We removed the temporaries, placed the final restorations using Excite bonding and Appeal luting agents (both Ivoclar Vivadent), adjusted the occlusion, and then sent him home for a few days to acclimate his mouth and jaws to his new teeth. On his last visit, we used the T-Scan II to perform a computerized analysis of the occlusion and check for prematurities and other problems. The bite and restorations passed the final inspection with flying colors, and the patient left extremely happy with a handsome new smile (Figures 9 and 10).
Figure 11. Pressed Porcelain to Zirconia (P2Z [MicroDental]) bridges 6x8 and 9x11.
Figure 12. P2Z bridges, interior view.
Figure 13. P2Z lower bridge.
Figure 14. P2Z interior.
Several new technologies, products, and techniques led to the successful analysis and resolution of this complicated case. The T-Scan II provided indispensable graphical information, helping us design and implement an occlusal scheme the patient found solid, comfortable, and aesthetically pleasing. MAC-Veneers by MicroDental Laboratories and MAC zirconium-based bridgework added a bright and natural beauty to the smile (Figures 11 to 14). The strength of MicroDentalÌs pressed porcelain allowed us to lengthen the teeth without worrying about breakage. Finally, bimanual manipulation helped us discover the real issue of the case: the dramatic disparity between the patientÌs centric occlusion and his centric relation. If we had not used the technique, we could have inadvertently restored the teeth to an unnatural bite that would have caused pain and other problems as the patient aged.
This case illustrates how important it is for cosmetic practitioners to stay current with innovations in aesthetic dentistry and implement them in their everyday practice.
Chiche GJ, Pinault A. Esthetics of Anterior Fixed Prosthodontics. Chicago, Ill: Quintessence; 1994.
Dawson PE. Evaluation, Diagnosis, and Treatment of Occlusal Problems. Mosby-Year Book. 2nd ed. 1989: 41-55.
Gurel G. The Science and Art of Porcelain Laminate Veneers. Chicago, Ill: Quintessence; 1st ed. 2003; 137-155.
Kerstein RB. A comparison of traditional occlusal equilibration and immediate complete anterior guidance development. Cranio. 1993;11:126-140.
Rosenthal L. The art of tooth preparation and recontouring. Dent Today. Apr 1997;16:48-55.
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