A Review of the Positive Influence of Crown Contours on Soft-Tissue Esthetics Richard P

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CLINICAL Technique REVIEW

Crown Restorations

A Review of the Positive Influence of Crown Contours on Soft-Tissue Esthetics Richard P. Kinsel, DDS; Bryan I. Pope, DMD, MSD; and Daniele Capoferri

Abstract: Successful crown restorations duplicate the natural tooth in hue, chroma, value, maverick colors, and surface texture. Equally important is the visual harmony of the facial and proximal soft-tissue contours, which requires the collaborative skills of the restorative dentist, periodontist, and dental technician. The treatment team must understand the biologic structures adjacent to natural dentition and dental implants. This report describes the potential for specifically designed restorative contours to dictate the optimal gingival profile for tooth-supported and implant-supported crowns. Showing several cases, the article explains how esthetic soft-tissue contours enhance the definitive crown restoration, highlights the importance of clinical evaluation of adjacent biologic structures, and discusses keys to predicting when the proximal papilla has the potential to return to a favorable height and shape.

sthetic crown restorations require precise control of the root interface relative to the convexity of the coronal enamel.3 multiple variables during crown fabrication in bio- Simulation of a natural tooth also depends on the location logic synergy with the surrounding soft-tissue pro- of the facial gingival zenith, defined as the most apical position file. This commendable goal frequently challenges of the free gingival margin. In healthy normal dentition, this is the treatment team. generally 1 mm distal to the midpoint of the tooth. This is most EThe free gingival margin has been described as knife-edged and pronounced in maxillary central incisors and reduced in lateral parabolic, following the buccal and palatal extent of the alveolar incisors and cuspids.4 bone and cementoenamel junction (CEJ) of the tooth.1,2 The facial The proximal surface contours of the CEJ are parabolic in shape contour of the soft tissue is greatly influenced by the concavity of and slightly concave. The interdental papilla occupies the proximal

Fig 1. Fig 2. Fig 3.

Fig 1. Crown margin has impinged upon connective tissue attachment. A periodontal probe was used for bone sounding the alveolar crest, which was 1 mm. The facial free gingival margin had the potential to move coronally by a process known as “creeping reattachment.” Fig 2. Once the existing crown was removed, the excessive apical placement of the preparation’s margin was apparent. Fig 3. Proper axial-gingival reduction was completed, and initial gingival margin was placed coronal to the CEJ of adjacent central incisor.

352 compendium May 2015 Volume 36, Number 5 clinical technique review | Crown Restorations

Understanding of the biology of soft tissues adjacent to natural dentition and the innate potential for spatial manipulation is of utmost importance. These concepts are directly applicable to implant-supported crowns.

Coronal Migration of the Free Gingival Margin Iatrogenic gingival recession, as in the first patient case shown, can be caused by restorative gingival margins that have impinged upon biologic width.10,11 The typical clinical appearance of the soft tissue Fig 4. when a crown margin has impinged upon connective tissue attachment is shown in Figure 1. The clinical appearance was confirmed by bone sounding using a periodontal probe,12 also shown in Figure 1. There was, thus, a general expectation that the facial gingiva margin would migrate coronally. Diagnostic casts were made for the fabrication of the provisional crown. After removal of the metal-ceramic crown, the underlying tooth preparation demonstrated excessive apical placement of the gingival margin and inadequate axial reduction (Figure 2). Initial cor- rective treatment involved smoothing the previously prepared cementum using a 16-fluted carbide finishing bur. Proper axial- gingival reduction was completed, and the gingival margin was Fig 5. placed coronal to the CEJ of the adjacent central incisor (Figure 3). The provisional restoration was designed with an under-con- Fig 4. The provisional crown facilitated the formation of a long junctional toured facial margin that facilitated coronal migration of the fa- epithelial attachment. Fig 5. The clinical appearance of the definitive cial gingiva over the root surface by a process known as creeping crown after 1 year in situ showed that the soft-tissue profile was stable and 13-15 symmetric with the left central incisor (natural tooth). Fig 6. Right central attachment. This has been reported to result in a stable, long incisor had a deficient composite restoration and palatal caries requiring a junctional epithelial adhesion or attachment, which is resistant full crown restoration. Fig 7. Non-impregnated retraction cord was inserted to bacterial infection.16,17 into the sulcus. Fig 8. The gingival margin of the completed crown preparation followed the soft-tissue outline. The convexity of the facial margin After 6 weeks, the optimal apical location and shape of the de- of the definitive ceramic crown established the position and contour of finitive facial margin was achieved (Figure 4). Impressions were the free gingival margin. Fig 9. The clinical appearance of the definitive ce- taken and the metal-ceramic crown delivered. The 1-year clinical ramic crown shown at 1 year post-treatment. Note the position and contour of the free gingival margins and absence of clinical inflammation. appearance demonstrated the stability and clinical health of the facial and proximal gingival profile (Figure 5).

Influence of Crown Contours on the Gingival Profile The free gingival margin can be moved apically using only the crown convexity without surgical crown lengthening. This requires that the osseous crest be located at an apical position that is > 2 Fig 6. Fig 7. mm.18,19 This permits displacement of the free gingival margin while preserving natural biologic width dimension. In this case, bone sounding was required to precisely determine the location of the alveolar housing. The patient seen in Figure 6 had a facial gingival asymmetry of the right central incisor tooth caused by altered passive eruption.20,21 A ceramic crown restoration was required due to inad- Fig 8. Fig 9. equate remaining coronal tooth support. Bone sounding using a periodontal probe indicated that the intracrevicular sulcus was 1 mm for the left central incisor and 2.5 mm for the right central area apical from the contact point.5 The restorative management incisor (altered passive eruption). Therefore, the free gingival of proximal soft tissue relies on many factors, including the em- margin could be positioned apically 1.5 mm without impinging brasure volume, location of the crestal bone from the restorative upon the junctional epithelial attachment. contact point, and periodontal/peri-implant health of the adjacent Prior to placement of the gingival margin, a non-impregnated tooth or implant.6-9 retraction cord was placed into the sulcus (Figure 7) to move the The following cases review how to manage the facial and free gingival margin apically to the same level as the adjacent proximal gingival profiles solely using restorative contours. central incisor. The position of the facial free gingival margin was

354 compendium May 2015 Volume 36, Number 5 Fig 10. Fig 11.

Fig 12. Fig 13.

Fig 10. Papillary deficiency between maxillary central incisor teeth and the mesio-distal dimensions were apparent during normal smile.Fig 11. Replacement of existing crown along with a porcelain-bonded proximal restoration placed on adjacent central incisor corrected the width discrepancy and the proximal embrasure space. Fig 12. The contours of the definitive ceramic crown and porcelain-bonded restoration enhanced the regenerative potential of the proximal papilla. Fig 13. Patient’s smile at 1-year follow-up.

determined by selective removal of stone from the master cast, The dental technician fabricated the ceramic crown and resin- developing symmetry with the adjacent central incisor (Figure bonded restoration. The preparation outline followed facial undu- 8). The convex CEJ contour of the definitive crown moved the lations of the natural tooth surface to camouflage the facial margin free gingival margin into an esthetic and biologically acceptable (Figure 11). The proximal restorative contour determined the form position. The 1-year appearance of the gingival profile confirmed of the interdental papilla (Figure 12). The patient’s smile seen at the clinical health and positional stability (Figure 9). 1-year follow-up (Figure 13) reflected the improved papilla height and form and demonstrated the long-term stability of the proximal papilla. Restoration of Interproximal Papilla Clinicians have attempted to surgically regenerate interproximal Implant-Supported Crown Contours papilla, generally with less-than-stellar results. A systematic review Although an implant-supported central incisor crown may closely of the literature by Blatz and Hürzeler attests to the unpredictability duplicate a natural tooth, differences of the free gingival margin of these techniques.22 Fortunately, the potential for incisal migration may lead to visual disharmony, as seen in Figure 14. Developing of papilla is robust when underlying proximal bone support is favor- optimal surrounding hard and soft tissues is challenging due to able.23 A recent clinical report demonstrated that papillary enhance- the flat restorative platform of dental implants in contrast to the ment with surgical augmentation was not possible without additive parabolic form of the CEJ found in natural teeth.25,26 alteration of the proximal contours of the central incisor teeth.24 When implant-supported crowns are adjacent to natural teeth, The patient shown in Figure 10 had a papillary height defi- the presence or absence of a papilla is dependent on the vertical po- ciency between the maxillary central incisors that was visible sition of the periodontal attachment on the adjacent tooth (Figure upon normal smile. Replacement of the defective right central 15). When the adjacent tooth lacks proximal attachment loss, a incisor metal-ceramic crown provided an opportunity to en- vertical distance from the contact point to the osseous crest of less hance the height of the proximal papilla, solely with the restor- than 5 mm possesses the highest potential for complete papilla ative contours. fill.27 This is assisted by the intact crestal bone and dentogingival The diagnostic wax-up determined that the mesio-distal size and dentoperiosteal fiber groups of the adjacent tooth.28 discrepancies could be addressed with a feldspathic porcelain In this case, the master cast was altered to duplicate the CEJ pro- resin-bonded restoration on the mesial of the left central incisor. file of the right maxillary central incisor tooth. The outline of the Favorable underlying osseous support afforded the potential for CEJ in the definitive metal-ceramic crown determined the gingival incisal migration of the proximal papilla. facial and proximal profile; this sometimes requires several months. www.compendiumlive.com May 2015 compendium 355 CLINICAL Technique REVIEW | Crown Restorations

final restoration placement (Figure 19), as well as in the radiograph (Figure 20).

Discussion and Conclusion Crown restorations placed in the esthetic zone are inherently com- plex. The collaborative knowledge and skills of an experienced treatment team are frequently required. Often, a nonsurgical, restorative solution can result in the desired gingival esthetics. However, a thorough understanding of the soft and hard tissues adjacent to the restoration is required to avoid an iatrogenic inflammatory response caused by excessive apical placement of the crown margins.29-32 Evaluation of the osseous support with periodontal probe Fig 14. sounding provides the restorative dentist valuable information regarding the feasibility of a restorative solution to a gingival de- Fig 14. The gingival frame fect. Facial gingiva of maxillary anterior teeth without periodontal before placement of the defini- 33 tive implant-supported ceramic disease are highly variable and range from 2 mm to 5 mm. The restoration demonstrated cervical convexity has been shown to form the gingival contour deficient papillae height.Fig 15. following facial root coverage procedures.34 The CEJ contour of Radiograph showed that the supporting osseous structure an implant-supported crown determines the facial and proximal would be expected to facilitate soft-tissue contours.35 regeneration of the papillae when the proximal contours simulate adjacent natural denti- ABOUT THE AUTHORS tion. Fig 16. The 1-year soft- tissue profile was favorable. Richard P. Kinsel, DDS Fig 15. Health Sciences Associate Clinical Professor, Department of Preventive and Restorative Dental Sciences, University of California San Francisco, San Francisco, California; Private Practice, Foster City, California

Bryan I. Pope, DMD, MSD Private Practice, Peninsula Periodontal Associates, San Mateo, California

Daniele Capoferri Owner, Swiss Dental Design, Foster City, California

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