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ePaper created 2017-03-17, 10:24:23 | version 1.38.0
Fig. 2a Fig. 2b Fig. 3 periimplant mucosal dimension in the pres- ence of a thick periimplant biotype com- pared with a thin biotype.24 It has also been suggested that a direct correlation exists between gingival biotype and susceptibility to gingival recession after surgical and restorative procedures. There is agreement in the literature regarding the influence of soft-tissue thickness on implant survival and long-term success. Fu et al. have proposed an approach to increas- ing soft-tissue thickness through the esthetic triad and PDP management, in which “P” is the implant position, “D” is the implant design and “P” is the prosthetic design.15 They indicate as key factors the use of platform-switched or parallel-walled implants, more palatal and apical implant placement, and concave prosthetic designs to reduce periimplant bone and soft- tissue loss. Abutment shape and contour Working on the abutment shape and con- tour has been one of the present authors’ main tasks in recent years, with a specific focus on the portion of the abutment located below the gingival level. The implant–abutment contours can be divided into two separate portions: the critical contour (the area of the implant abutment and crown located immediately apical to the gingival margin) and the subcritical contour (located apical to the critical con- tour). These two entities will exist provided that su(cid:3)cient running room (defined as the distance from the implant neck to the free gingival margin) is present. Both the critical and the subcritical contours, if prop- erly modulated and shaped, may be used to modify the esthetic outcome of the restoration.16 As already summarized, to prevent buc- cal bone resorption, the literature suggests placing the implant at the cingulum of the future restoration14 or 1.5–2.0 mm palatal to the incisal margin of the central maxillary incisor.13 However, this approach can lead to problems that may jeopardize the esthetic outcome and the survival of the implant. For one thing, the crown contour created by such placement is substantially different from what exists in nature. In natural dentition, the tooth contour is basi- cally formed by two separate entities: the emergence profile and the cervical contour. 58 — issue 2017 Advanced Implant Esthetics Article Figs. 2a & b (a) A natural maxillary tooth. (b) The lateral view shows a convexity corresponding to the cervical contour. Fig. 3 The EA is formed by the junction of a line through the long axis of the tooth (red line) and a tangent drawn to the coronal of the tooth as it emerges from the sulcus (blue line). Crown contour and emergence profile The emergence profile is straight and cor- responds to the part of the tooth emerg- ing from the gingiva. The cervical contour is convex and located at the bottom of the gingival sulcus, corresponding to the area where the enamel overlaps the cemen- tum at the cementoenamel junction (Figs. 2a & b). This convexity has been identified by Wheeler,17 who referred to it as the cervical ridge or cervical contour, and it has the function of holding the gingiva under definite tension.