Use of Additive Dentistry Decreases Risk by Minimizing Reduction

K. Michael Palmer, DMD

It wasn’t that long ago that adults in their later years might have expected to lose all or most of their permanent dentition. Over the past half-century, however, improved dental care, awareness, and education have helped make it possible for adults to maintain their dentition into maturity. Preserving tooth structure in younger individuals has, thus, become far more vital than ever before. Although it is commonly believed that dentistry performed with conventional crown-and-bridge methods is permanent, the research does not support that assumption.^1,2 Many traditional crown-and-bridge techniques, as well as modern, esthetically driven treatment plans, result in the loss of considerable amounts of healthy tooth structure and add significant biomechanical risk over an individual’s lifespan.³ With the advent of stronger, thinner restorative materials and adhesive techniques, additive dentistry may be employed to eliminate the need for significant tooth preparation. The risk to the restorative material (porcelain fracture) is still present, but the risk of weakening the teeth with more invasive procedures is eliminated, thereby conserving the natural tooth.

All cases do not lend themselves to minimal or no-preparation techniques, but this particular one did. The patient’s dentition was restored utilizing intact enamel, adhesive dentistry, and etchable ceramic materials that require less than 1 mm of occlusal reduction without a significant loss of strength.⁴

Clinical Case Overview

Patient History and Chief Complaint: A 38-year-old woman sought advice for cosmetic dentistry. She reported she had never been happy with the appearance of her teeth and complained her smile was becoming worse due to a history of teeth grinding for many years (Figure 1 and Figure 2). Her chief complaint was a desire to have a big, beautiful smile, but she was concerned about having all of her teeth prepared for full crowns.

A review of the patient’s medical history revealed a positive response for gastroesophageal reflux disease (GERD). The patient was being treated with omeprazole, which has been shown to cause xerostomia.⁵ No other medical conditions or allergies were noted. She was very health conscious, worked out regularly, and took vitamin supplements.

As for dental history, the patient reported routine hygiene visits with her previous dentist for many years. Her third molars had been impacted and were removed during her teenage years. She bleached her teeth in the past with little success and felt self-conscious about her smile. Her perception was that her teeth had become shorter over the past 5 years. She had worn a nociceptive trigeminal inhibitor appliance in the past and found it uncomfortable. She reported decreased salivation, pitting on the biting surfaces of her teeth, occasional bleeding gums, recession, and an unpleasant taste. She also gave a positive history of receiving Restylane^® (Q-Med, www.restylane.com) injections in her lips.

Diagnosis, Risk Assessment, and Prognosis

The author notes that prognosis is established by taking the risk assessment into consideration as well as the age of the patient, the presence or absence of the contributing factors of disease, the expected lifespan of the patient, diet, and the patient’s treatment of teeth. Prognosis is determined without considering intervention, so the patient can understand potential outcomes if the disease process is left untreated.

Periodontal: The patient exhibited light bleeding on probing with depths no greater than 3 mm except around teeth Nos. 3, 14, 19, and 30, which had isolated 4-mm pockets. Less than 1 mm of recession was noted on the buccal surfaces of teeth Nos. 5, 8, 9, 12, 21, and 28 through 30. Abrasion was seen on tooth No. 21. The diagnosis for her periodontal condition was AAP II, early localized periodontitis (Figure 3 and Figure 4).

Risk: Low
Prognosis: Good

Biomechanical: Clinical examination revealed defective restorations on teeth Nos. 5, 18, 19, 30, and 31 (Figure 5 and Figure 6). Teeth considered to be structurally compromised or that would benefit from cuspal coverage due to the size of the restorations were Nos. 18 and 31.6 Erosion was generalized throughout both arches, but was more significant on teeth Nos. 5, 6, 18 through 21, and 28 through 30. Radiographic examination revealed recurrent decay beneath the restorations on teeth Nos. 14, 15, 18, 19, and 29. A caries susceptibility test measured 7705, suggesting a high bacterial index in the patient’s mouth.⁷

Risk: High
Prognosis: Fair (hopeless for teeth Nos. 14, 15, 18, 19, 29, and 30, which had active decay)

Functional: Minimal attrition was viewed on teeth Nos. 3, 4, 13, 14, and 18. Moderate-to-severe attrition was observed on teeth Nos. 2, 5 through 12, and 19 through 31 (Figure 4 through Figure 6). The patient had a normal range of motion and a 51-mm opening without pain. No pain was noted upon loading joints; neither was there any muscle discomfort following an immobilization test. There were no temporomandibular joint sounds. Tooth mobility was noted on teeth Nos. 7 through 10; a diagnosis of primary occlusal traumatism was made based on the lack of appreciable bone loss around the teeth. During the occlusal evaluation, it was noted that teeth Nos. 2 and 31 were in cross bite. Because the patient reported a history of teeth grinding and a positive response for changes in teeth lengths, the diagnosis of “acceptable function” was eliminated. Because occlusal problems were evident and restorative dentistry was planned, a deprogramming device (Kois deprogrammer) was used to verify a reproducible position for the joints and muscles.⁸ After deprogramming the muscles, the mandible moved posteriorly and a diagnosis of occlusal dysfunction was made.

Risk: Moderate
Prognosis: Fair

Dentofacial: On initial presentation, the patient showed very little tooth structure in a full smile and no upper teeth at all with her lips in a reposed or resting position (Figure 2 and Figure 7), placing her in a low-risk “dentofacial” category for esthetics.⁹ The full smile revealed a worn dentition, spacing, and an asymmetrical smile line with her teeth canted. Further examination exposed uneven gingival architecture with lips retracted (Figure 4), but because there was no gingival display, it was not a concern for the patient. The full-face photograph showed brachycephalic facial form and some asymmetry in the mandible (Figure 1). Her masseter muscles appeared hypertrophic. The profile view showed a somewhat prognathic mandible (Figure 8). Following a consultation with the patient concerning her esthetic desires, a normally low-risk esthetic case was elevated to a moderate level due to her high expectations.

Risk: Moderate
Prognosis: Fair

Medical: ASA I
Risk: Low
Prognosis: Good
 

Treatment Goals

Various issues needed to be addressed in this patient’s treatment:

• Meet or exceed the patient’s esthetic requirements to achieve a more pleasant appearance (show more teeth, whiten teeth, eliminate spaces).
• Conserve healthy tooth structure.
• Remove carious lesions and restore.
• Reduce incidence of future decay by instituting a caries management program.
• Design a functional system that does not prematurely load the teeth during chewing.
• Reduce or eliminate erosion.

Treatment Plan

This case required enhancement of esthetics and reduction of the long-term risk of pathologic tooth wear and decay, as well as minimizing erosion caused by innate and environmental influences. Determining centric relation made it possible to alter the vertical dimension of occlusion, thus facilitating the esthetic and occlusal change.¹⁰ Lithium disilicate (IPS e.max^®, Ivoclar Vivadent, www.ivoclarvivadent.com) veneers and onlays were placed on the anterior and posterior teeth, respectively, utilizing adhesive dentistry principles. Only carious, unsound, or unsupported tooth structure was removed. Maxillary anterior esthetics were altered by adding to the facial and incisal surfaces of the teeth without negative consequences to the envelope of function.¹¹ The occlusion was successfully managed by using centric relation as the joint position (P1), equal-intensity simultaneous contact on all posterior teeth (P2), and anterior guidance (P3).

Phase 1: Establish Centric Relationship and Initiate Preventive Protocols

Initial treatment required the fabrication of a Kois deprogrammer. The patient wore the deprogrammer 24 hours a day, except for eating, for a period of 1 month. After verifying a reproducible position, a centric-relation bite registration was taken with the deprogrammer in place. A Kois face-bow transfer was taken to establish a relationship of the maxillary arch to a relative hinge axis and to the horizon for esthetic considerations.¹² Secondly, all teeth requiring only direct restorations were restored. A caries management program was introduced, which included fluoride varnish applications, alkaline-based treatment rinse (CariFree^® Treatment Rinse, Oral BioTech, www.carifree.com), xerostomia management, and 4-month continuous care appointments.

The following erosion-management protocols were recommended: reduced acid intake; modified diet; chewing gum for increased salivary flow; and remineralization strategies utilizing casein phosphopeptide and amorphous calcium phosphate (RECALDENT™ [CPP-ACP]) (MI Paste™, GC America, Inc., www.gcamerica.com) and/or fluoride gel.¹³

Finally, a medical consultation was requested to consider a change in the patient’s GERD medication, omeprazole, to one that would not decrease salivary flow.

Phase 2: Laboratory Preparations (Diagnostic Wax-up)

The maxillary cast was mounted utilizing the Kois dentofacial analyzer (Figure 9). The mandibular cast was then mounted with the centric-relation record. The patient believed her initial point of contact following deprogramming was the premolar region on the left side. This was verified by the centric-relation record, which showed centric occlusion as a single contact on teeth Nos. 12 and 20 (Figure 10). The desired lengths of the maxillary teeth were determined by the esthetic determinants—ie, lips in repose and full smile.¹⁴ The dentofacial analyzer was adjusted to increase the incisal edge of the maxillary anterior teeth, and a full-contour wax-up was completed with the teeth touching the platform (Figure 11). The maxillary posterior teeth were leveled to blend with the anterior teeth. Since the casts were mounted utilizing a joint position instead of maximum intercuspation, the vertical dimension was opened in a reliable manner to restore the worn tooth structure. The wax-up of the mandibular teeth was initiated using the esthetic determinant of 1 mm of tooth display in repose, which indicated the addition of 2 mm to the incisal edges. The lower anteriors were brought into light contact with the lingual of the uppers with the canines in contact. Then, the lower posterior teeth were created in a more ideal cusp-to-fossa relationship (Figure 12). The wax-up was then duplicated to aid in the fabrication of the provisional restorations.

Phase 3: Restorative

The restorative phase began with provisonalization of the mandibular arch with bis-acryl temporary material directly over the unprepared teeth. Utilizing the deprogrammer, the lower molars were equilibrated against the upper molars, which were not to be restored, and the mandibular anterior teeth were brought into contact with the lingual of the uppers. Next, the maxillary anterior teeth were prepared by placing a very light chamfer around the facial gingival margin and softening the incisofacial line angle. No other facial reduction was performed. The occlusal surfaces of the premolars were smoothed, the amalgam restoration on tooth No. 5 was removed, and an inlay preparation was designed. Final impressions were made of the maxillary arch, and a bite registration was taken. Because the lower provisionals were equilibrated with the deprogrammer, it was possible to record a bite registration in maximum intercuspation, which was coincidental with the new centric occlusion. The maxillary provisionals were fabricated, and the occlusion on the canines and premolars was verified.

The esthetics of the provisional restorations were evaluated to ensure that the changes made were acceptable. The maxillary veneers and onlays were fabricated of lithium disilicate (IPS e.max) against the lower provisional, utilizing the maxillary provisionals as an esthetic guide. The maxillary anterior restorations were bonded using enamel bonding protocols and veneering cement (RelyX™ Veneer Cement, 3M ESPE, www.3MESPE.com). The premolars were bonded in place using dual-cure resin cement (RelyX™ ARC, 3M ESPE) with similar enamel bonding protocols (Figure 13). The occlusion was refined on the lower provisionals.

The lower arch was restored in two phases to help simplify impressioning and final insertion. The first phase began with the removal of old restorations on teeth Nos. 18, 19, 30, and 31. Core restorations were placed in the deeper cavity preparations, and onlay preparations were performed on the molars.¹⁵ The molars were impressed, and restorations were fabricated and inserted with the same bonding protocol as the maxillary posterior teeth.

The remaining mandibular teeth were not prepared except where cervical restorations were previously placed (Figure 14). A final impression was taken, then restorations were fabricated that mimicked the provisional restorations. The final restorations were inserted and the occlusion was refined utilizing the previously fabricated deprogrammer (Figure 15 and Figure 16).

Discussion

An evaluation of the teeth in both repose and full-smile showed both to be within acceptable esthetic limits (Figure 17 and Figure 18). The patient commented that she no longer had to force her smile to show teeth, therefore making her appearance more relaxed. The esthetic changes improved both her dental appearance and facial proportions. Both the frontal and profile views of the patient showed increased lower-face height (Figure 19 and Figure 20).

Conclusion

The goal in restorative dentistry should be to minimize long-term risk whenever possible. This case offered challenges in three different areas—biomechanics, function, and dentofacial. The damage to the teeth had already occurred, and the choice to restore them was already made. Considerations were discussed for orthodontic treatment, but because the teeth would require restoration anyway, the patient opted to forego that treatment. Traditional crowns could have been placed, but they would have significantly increased biomechanical and endodontic risk.

The key learning point from this case is that opening the vertical dimension of occlusion eliminated the need to remove excessive amounts of healthy tooth structure. Furthermore, the esthetic desires of the patient could not have been met without increasing the height of both the maxillary and mandibular arches. The occlusal dysfunction was more easily treated by developing a better occlusal scheme, one that allowed for equalizing the posterior occlusal contacts in a position that the patient was able to find easily without interference. Lastly, the areas most affected by GERD—exposed dentin—were covered with porcelain, thereby minimizing the erosion.

This evidence-based systematic approach to data collection, diagnosis, risk assessment, and treatment planning allowed for a more predictable result.^16,17

Acknowledgment

The author would like to acknowledge the laboratory procedures and ceramic work performed by Kyle Forbes, CDT, of Forbes Dental Studio in Florence, Kentucky.

References

1. De Backer H, Van Maele G, De Moor N, et al. A 20-year retrospective survival study of fixed partial dentures. Int J Prosthodont. 2006;19(2):143-153.

2. De Backer H, Van Maele G, Decock V, Van den Berghe L. Long-term survival of complete crowns, fixed dental prosthesis, and cantilever fixed dental prosthesis with post and cores on root canal-treated teeth. Int J Prosthodont. 2007;20(3):229-234.

3. Kois JC. Dental morality or misguided science? Gen Dent. 2008;56(3):236.

4. Strassler, HE. Clinically relevant testing of dental porcelains for fatigue and durability with an innovative mouth motion simulator. Inside Dentistry. 2009;5(8);38-39.

5. Teare JP, Spedding C, Whitehead MW. Omeprazole and dry mouth. Scand J Gastroenterol. 1995;30(3):216-218.

6. Larson TD, Douglas WH, Geistfeld RE. Effect of prepared cavities on the strength of teeth. Oper Dent. 1981;6(1):2-5.

7. Gallez F, Fadel M, Scruel O, et al. Salivary biomass assessed by bioluminescence ATP assay related to (bacterial and somatic) cell counts. Cell Biochem Funct. 2000;18(2):103-108.

8. Jayne D. A deprogrammer for occlusal analysis and simplified accurate case mounting. J Cosmet Dent. 2006;21(4):96-102.

9. Bakeman E, Kois J. Maximizing esthetics/minimizing risk: the line of predictable success. Inside Dentistry. 2005;1(1):16-24.

10. Kois JC. Occlusal vertical dimension: what is the controversy? Compend Contin Educ Dent. 1997;18(12):1164.

11. Dawson PE. Evaluation, Diagnosis, and Treatment of Occlusal Problems. 2nd ed. St. Louis, MO: CV Mosby Co; 1989:274-298.

12. Kois JC. Functional Occlusion: Science Driven Management Manual. Seattle, WA: Kois Center; January 2011:79.

13. Lussi A, Hellwig E, Ganss C, Jaeggi T. Buonocore Memorial Lecture. Dental erosion. Oper Dent. 2009;34(3):251-262.

14. Mack MR. Facially generated occlusal vertical dimension. Compend Contin Educ Dent. 1997;18(12):1183-1194.

15. Kois DE, Chaiyabutr Y, Phillips KM, Kois JC. A comparison of various preparation designs for adhesively retained posterior ceramic onlays: a fatigue load study. Presented at: 73rd Annual Scientific Meeting of the Pacific Coast Society for Prosthodontics; June 2008; Kona, Hawaii.

16. Kois JC. New challenges in treatment planning shifting the paradigm toward risk assessment and perceived value. J Cosmetic Dent. 2011;26(4):62-69.

17. Kois JC. New challenges in treatment planning: incorporating the fundamentals of patient risk assessment part 2. J Cosmetic Dent. 2011;27(1):110-121.

About the Author

K. Michael Palmer, DMD
Private Practice
Crestview Hills, Kentucky