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

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A Review of the Positive Influence of Crown Contours on Soft-Tissue Esthetics Richard P 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-tis- sue 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 attach- ment 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 gingi- val 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 prepa- ration 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 erup- tion.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 dis- crepancy 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
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