Enhancement of the Natural Dentition

Using esthetic crown lengthening and all-ceramic restorations to restore natural form and function.

Paul S. Petrungaro, DDS, MS; Steven A. Gorman, DDS; Edgar Jimenez, CDT

The communication between the esthetic dentist, periodontal surgeon, and laboratory technician is critical to the diagnosis and sequencing of treatment when completing a case that requires both the repositioning of the hard and soft tissues in order to correct the compromised dentogingival complex and reestablish adequate proportions of the dentition. This article will demonstrate the process of esthetic crown lengthening and the subsequent restorative dentistry to enhance an esthetically compromised natural dentition.

The position of the teeth and gingival tissues is a key determinant for the successful outcome of esthetically driven restorative treatment planning.^1-4An interdisciplinary treatment approach is often necessary to address the different parameters that need to be corrected to reestablish a healthy and symmetrical gingival and alveolar complex.^5-7 Some of the parameters that need to be taken into account are defining the desired tooth position and their corresponding free gingival margin position.⁸ The restorative/esthetic clinician must create a symmetrical and harmonious relationship between the lips, gingival architecture, and position of the natural teeth.⁹Spear⁴ refers to this diagnostic methodology as “facially generated treatment planning,” where the maxillary central incisor edges determine where the soft tissue (gingiva) and bony crest should be positioned. Altering the free gingival margin may require alteration of the crest of the alveolar bone, depending on the biologic width dimensions.

Determining whether to remove some of the alveolar structures in addition to the gingival can be made by taking into account factors such as the maxillary incisal edge position, proportions of the teeth, final position of the free gingival margin, sounding measurements, and biologic width.⁸

The dentogingival complex is compromised of the connective tissue attachment, epithelial attachment, and the gingival sulcus. Kois¹⁰stated that, “the most critical relationship for biologic health when the clinician is placing a restoration at or below the free gingival margin (FGM) is the margin location relative to the bony crest. The distance from the free gingival margin to the osseous crest on the facial aspect should be 3 mm.” Interproximally, on anterior teeth, this distance should be 4 mm because of the curvature of the cemento-enamel junction (CEJ) and the position at the bony crest relative to it. The height of the interdental papillae also can be predicted to be maintainable 4 mm incisal to the osseous crest between anterior teeth with normal root proximity, which is approximately 2 mm to 3 mm at the osseous crest. Keeping these parameters in mind, the decision must be made where to place the restorative margins. Ideally, the margin should be placed at the free gingival crest or slightly supragingival. If an intracrevicular margin is required for esthetic reasons, it should not be placed more than 0.5 mm into the sulcus to avoid detrimental effects to the attachment apparatus.

Coslet et al¹¹ and Kois¹² also have described biologic width in a way that compares the distance from the alveolar crest to the free gingival margin and divides this distance into three categories:

Normal-crest patients (about 70% of patients) have approximately a 2-mm combined epithelial and connective tissue attachment and an average 1-mm to 3-mm sulcus depth. If the sulcus depth is > 1 mm, the free gingival excess can be resected safely and, on healing, will result in a dentogingival complex measuring 3 mm on the facial aspect.
High-crest patients often have a shallower sulcus depth and a combined epithelial and connective tissue attachment of < 2 mm. These patients have relatively stable free gingival margin positions and are not prone to recession upon manipulation of the tissues.
Low-crest patients often have normal sulcus depth (1 mm to 3 mm) and a combined epithelial and connective tissue attachment that is > 2 mm. These patients are highly prone to recession and must be treatment planned accordingly. The free gingival margin of low-crest patients will tend to reposition apically and turn into a normal crest situation after gingival retraction or surgery.

Understanding these categories and their clinical applications can lead to successful outcomes, predictably and routinely. The following section will outline the treatment protocols for a normal-crest patient, and the management of gingival asymmetry, a canted occlusal plane, and excessive gingival volume.

Case Report

A 42-year-old healthy, non-smoking woman presented with the chief complaint of the esthetics of her natural teeth and gingival recession in the mandibular arch (Figure 1, Figure 2, Figure 3). Her natural teeth were antibiotically stained, dark, and striped. Previously, she had had composite bonded veneers placed on the upper anterior teeth. The clinical examination revealed an end-to-end Angle Class II occlusion with a 15% overbite and 2 mm of overjet. The esthetic evaluation revealed improper tooth shapes, very bulky and full contours, and the appearance of too much prominence in the anterior teeth. The arch form was narrow and V–shaped, giving even more prominence to the anterior teeth and inadequately filled buccal corridors. Overall, there was excessive gingival display on full smile even though there was generalized recession in the gingival tissues related to the bulky restorations. There was also a significant cant to the upper arch, with the right side positioned more incisally than the left. Additionally, there was a midline cant consistent with this positioning.

The treatment plan consisted of periodontal crown lengthening at teeth Nos. 3 through 14 to harmonize the tissue levels and aid in correcting the cant in the upper arch. A tunnel graft procedure was accomplished simultaneously to the crown-lengthening procedure to correct the gingival recession of teeth Nos. 21 through 28. The restorative plan was for indirect-bonded porcelain restorations on teeth Nos. 3 through 14, 18, and 20 through 29.

A facebow transfer was taken in addition to upper and lower study models, followed by a full-case diagnostic wax-up (Figure 4). After administration of an appropriate local anesthetic, sounding measurements were taken at each tooth in the maxillary arch to be crown lengthened (Figure 5). These measurements are significant for managing the biologic width space and needing (or not needing) to perform osseous resectioning to maintain an adequate biologic width space after the required gingival tissues are removed for the esthetic treatment planned. After all of the sounding measurements were obtained, and using a surgical stent obtained from the diagnostic waxing, submarginal incisions were performed from teeth Nos. 3 through 14, removing the correct amount of gingival tissue for the desired tooth shapes (Figure 6).

Full-thickness mucoperiosteal flaps were reflected and tissue tags were removed. Figure 7 shows the appearance of the alveolar crest prior to osseous repositioning. Using rotary instrumentation, removal of both supporting (ostectomy) and non-supporting (osteoplasty) bone was accomplished, followed by root planing and detoxification of the root surfaces with citric acid, pH 1 (Figure 8). The flaps were then repositioned and sutured with 5-0 monocryl (Ethicon, https://www.ethicon.com) sutures in a continuous-sling suturing technique (Figure 9, Figure 10, Figure 11).

The tissues were allowed to heal uneventfully. Figure 12 shows a 2-week postoperative view, whereas the 2-month postoperative view can be seen in Figure 13. The patient then returned to the restorative cosmetic dentist for completion of the case. Teeth Nos. 3 through 5 and 12 through 14 were prepared for all-ceramic crowns and teeth Nos. 6 through 11 were prepared for porcelain veneers that broke contacts between the teeth and wrapped to the lingual to hide all of the dark color from the antibiotic staining. Once the preparations were done, a polyvinylsiloxane impression was taken. The provisional matrix of the wax-up was used to make a shade B1 Structur^® (VOCO, https://www.vocoamerica.com) provisional. The provisional was segmented with teeth Nos. 3 through 5, 6 through 11, and 12 through 14 as groups. Segmental bite registration was taken replacing these provisional groups and the anterior portion included a horizontal “stick bite” to double check the facebow mounting (Figure 14). The Ivoclar Natural Die Material dentin shade guide (Ivoclar Vivadent, https://www.ivoclarvivadent.com) was used to identify the gingival shades of the prepared teeth as ND 5 and the main body and incisal areas as ND 9, thus, very dark.

After inserting the provisionals with CAULK Fynal^® cement (Dentsply CAULK, https://www.caulk.com) and equilibrating the occlusion, an impression and facebow of the upper arch with the provisionals was accomplished. A new impression of the lower equilibrated arch was also taken at this time. Then, a model of the provisionals was mounted with a facebow, the lowers were mounted to that and then the working model was mounted to the lower by way of the segmented bite registration. This was again verified with the “stick bite” taken earlier.

The patient was very pleased with the esthetics and “feel” of the provisionals. She felt they looked like real teeth, she could feel the difference in the missing bulkiness she had had before, and she said that her bite felt much more solid as well. In the end the patient was looking for a shade similar to the Vita 1M1 shade with a splash of OM3 to make them “pop” a little. It was necessary to hide the dark color underneath, so an opaque ingot was used to start. The patient was appointed to return in 3 days to verify phonetics, esthetics, and teeth/lip relationships. All appeared acceptable. The decision was made at this time to only fabricate the veneers for teeth Nos. 7 through 10 in order to test the formula for covering the dark teeth, rather than complete the whole case and not be happy with it.

In the laboratory, the ceramist chose GC Initial™ I.Q. (GC America, https://www.gcamerica.com) in B-O-O, the ingot most likely to cover dark teeth. It is the B-O shade with O (added opacity). Upon the patient’s return, the veneers for teeth Nos. 7 through 10 were tried in and evaluated, but they did not provide adequate coverage. After considering all options, it was determined that more aggressive preparation of the facials of these teeth was warranted. The preparations were touched up, new impressions were made, and new provisionals were fabricated for the anterior segment. The new restorations were again fabricated with the B-O-O ingot (Figures 15, Figure 16, Figure 17).

When the final restorations were ready, the veneers and crowns were inspected on working and soft-tissue solid models for integrity of margins, contacts, and passive fits. An incisal putty guide was fabricated from the provisionals and checked against the incisals of the finished restorations to ensure adherence to the case specifications. All aspects appeared acceptable. After adequate anesthetic was administered, all crowns and veneers were tried in for individual fit and color coverage and as a group for smile design evaluation, contour, shape, contacts, surface anatomy and texture, color mapping, and overall case appeal. Everything was as prescribed, and the patient was very happy with all aspects of the case.

The restorations were all placed after etching the porcelain with hydrofluoric acid to silanate the internal surface. The procedure involved etching the prepared tooth surfaces with phosphoric acid, rewetting the dentin surface with Gluma (Heraeus, https://www.heraeus-dental-us.com), placing unfilled resin (Optibond^®, Kerr Corporation, https://www.kerrdental.com) on the teeth and the internal surface of the restorations and using a clear shade of the luting agent (Insure, Cosmedent, https://www.cosmedent.com) in the restorations. After removal of excess luting agent, the restorations were all cured and further excess cement was removed from the marginal areas with interproximal carvers and finishing strips. The lingual margins were blended and refined with fine finishing diamonds. Proximal areas were refined with fine finishing strips. Occlusion was evaluated and adjusted in centric, protrusive, and lateral excursives. All surfaces were smoothed and polished with rubber porcelain polishing points and finished with porcelain polishing paste. Figure 18 shows the case-complete smile view. Note the positioning of the restorations and the gingival architecture in relationship to the upper lip. Figure 19, Figure 20, Figure 21 show the right, anterior, and left clinical views respectively. Also note the corrected gingival contours, emergence profiles, soft tissue interproximal architecture, and healthy dentogingival complex obtained.

Conclusion

Understanding the dimensions of the dento-gingival apparatus and its relationship to the restorative/cosmetic dentistry is paramount in the successful treatment of not only cases that require gingival and osseous repositioning, but routine cases as well. The management of patients requiring crown-lengthening procedures as a component to their treatment entails a comprehensive knowledge of the classifications of the distance from the free gingival margin to the alveolar crest as outlined earlier from Coslet⁸ and Kois.⁹ Communication and a team approach to patient care, along with a thorough understanding of restorative materials and protocols, can result in natural-looking restorations that are not only esthetically pleasing, but biologically sound as well.

References

1. Chiche GJ, Pinault A. Esthetics of Anterior Fixed Prosthodontics. Quintessence Publishing; 1994.

2. Rufenache CR. Fundamentals of Esthetics. Quintessence Publishing; 1990.

3. Garber DA, Salama MA. The aesthetic smile diagnosis and treatment. Periodontol 2000. 1996;11:18-28.

4. Spear FM, Kokich VG, Mathews DP. Interdisciplinary management of anterior dental esthetics. J Am Dent Assoc. 2006;137 (2):160-169.

5. Becker W, Ochsenbein C, Becker B. Crown lengthening: the periodontal-restorative connection. Compend Cont Educ Dent. 1998; 19(3):239-254.

6. Allen EP. Surgical crown lengthening for function and esthetics. Dent Clin North Am. 1993;37(2):163-179.

7. Kay HB. Esthetic considerations in the definitive periodontal prosthetic management of the maxillary anterior segment. Int J Periodont Rest Dent. 1982;2(3):44-59.

8. Kinzer GA. Esthetic crown lengthening: An alternative technical for surgical communication. Inside Dentistry. 2008;4(1):24-32.

9. Lowe RA. Clinical use of the Er,Cr:YSGG laser for osseous crown lengthening: redefining the standard of care. Pract Proced Aesthet Dent. 2006;18(4):S2-S9.

10. Kois JC. Altering gingival levels: the restorative connection. Part 1. Biologic variables. J Esthet Dent. 1994;6(1):3-9.

11. Coslet GJ, Vanarsdall R, Weisgold A. Diagnosis and classification of delayed passive eruption of the dentogingival junction in the adult. Alpha Omegan. 1977;70(3):24-28.

12. Kois JC. New paradigms for anterior tooth preparation. Oral Health. 1988;88(4):19-30.