The Use of CAD/CAM Cobalt-Chromium Framework to Optimize Subgingival Prosthetic Contours and Improve Esthetics: Anterior Mandibular Case Reports.

Although implant therapy in esthetically relevant areas is currently based on a prosthetically driven philosophy, anatomical and technical factors may impair ideal implant placement. In these scenarios, the clinician is frequently asked to solve the discrepancy between the implant emergence and the ideal coronal anatomy of the final restoration. This report describes how changes of the implant abutment-crown contour in specific locations may be intentionally promoted to determine improvements of the peri-implant soft tissues and overall esthetic integration. Cobalt-chromium alloys together with computer-aided design/computer-assisted manufacture technologies are critical factors in achieving this goal. Case reports for the mandibular anterior dentition demonstrated the ability to enhance biologic and esthetic results of malpositioned implants.

Effect of 2 impression techniques on the dimensional accuracy of working implant prosthesis models: an in vitro study.

PURPOSE: Implant impressions and working models form integrated precision systems for registration and transmission of clinical data. The components of implant systems have a dimensional tolerance capable of introducing inaccuracies in the impression, thus in the prosthetic framework. This article aimed at comparing 2 repositioning impression techniques: one using impression copings (conventional technique) and the other using the final abutments as impression copings (interceptive technique). MATERIALS AND METHODS: Two experimental models, one with 4 parallel implants and the other with 4 nonparallel implants, were used to make silicone impressions. Twenty impressions were made with the conventional technique, and a further 20 were made with the interceptive technique. Three-dimensional images acquired with a three-dimensional scanner were measured using a three-dimensional image analysis software, comparing models obtained from the impressions with the experimental models. Data were statistically analyzed by means of confidence intervals calculated with the mean (α = 0.05), descriptive (box plot), and bivariate analyses. RESULTS: Statistic analysis highlighted significant differences among models obtained using both techniques: the interceptive technique generated working models with less distortion and variability. CONCLUSIONS: For internal-connection implants, the interceptive technique provided significantly more precise working models than did the conventional technique.

The evaluation of marginal gap with and without optical aids: clinicians versus technicians.

PURPOSE: This study investigated the reliability of visual assessment of marginal gaps in relation to the use of magnification and the operator's profession. MATERIALS AND METHODS: A titanium bar was notched, simulating 40 marginal gaps, and 35 operators performed a quantitative evaluation of the incisions. RESULTS: Visual examination was neither sensitive nor specific, as an extreme variability of data was recorded. The precision of readers improved with magnification aids only for clinicians; technicians were significantly more accurate in evaluating the incision's width. CONCLUSION: The visual examinations were inadequate to decide the clinical acceptability of a restoration with regard to its marginal fit.

Effect of implant angulation, connection length, and impression material on the dimensional accuracy of implant impressions: an in vitro comparative study.

BACKGROUND: With regard to implant-supported prostheses, to date no technique has been proven to guarantee a completely passive fit of prosthetic frameworks. Several clinical variables may affect the precision of impressions, particularly in the presence of implants. PURPOSE: To compare the accuracy of implant impressions made with different materials, lengths of impression coping connections, and not parallel position of the implants. MATERIALS AND METHODS: A calibrated testing device allowing reproducible standardized positions was used. Two control groups of master models and eight experimental groups with predetermined undercuts were used to make addition silicon and polyether implant impressions by means of the open-tray pick-up technique. Four reference distances were evaluated on each study cast by using a profile projector and a standardized measurement protocol. The data were statistically analyzed by means of three-factor analysis of variance. RESULTS: The impressions made in the presence of angulated implants were significantly less accurate than the ones made with parallel implants. The tested addition silicon resulted advantageous in presence of nonparallel implants whereas the polyether achieved the best results with parallel implants and standard impression copings. CONCLUSIONS: The angulation of the implants may cause strains of impressions, probably because of the higher forces required for the impression removal. Moreover, undercuts negatively affected the impression accuracy. More accurate casts were obtained using the tested addition silicon in the presence of nonparallel implants and using a standard length connection of the copings in the presence of parallel implants, respectively.

Edentulous site enhancement: a regenerative approach to the management of edentulous areas. Part 2: Peri-implant tissues.

The appearance and long-term stability of peri-implant bone, mucosa, and gingiva determine the success of implant-supported prostheses from both the esthetic and functional standpoints. Any surgical or prosthetic technique that takes into consideration only some variables, or that only intervenes in a limited phase of treatment, is a potential source of a partially successful and/or unpredictable clinical outcome. This article describes the underlying principles and surgical-prosthetic procedures of a systematic regenerative approach, edentulous site enhancement (ESE). The goal of this approach is to improve the anatomy of edentulous sites. Applied to implant dentistry, this approach enables peri-implant tissue to be managed predictably, optimizing the functional and esthetic result of restorations with regard to treatment time, number of surgical stages, long-term prognosis, and incidence of complications. The principles underlying the ESE approach, which are independent of any specific implant system, are applicable in the majority of clinical situations, regardless of the esthetic requirements.

Edentulous site enhancement: a regenerative approach for the management of edentulous areas. Part 1. Pontic areas.

The successful esthetic integration of a prosthesis is dependent on the anatomic site in which the restoration is inserted. Edentulous site enhancement is a regenerative approach based on the following: (1) anatomic evidence that the morphology of soft tissues is dependent on the underlying support (bone, roots, implants) but also significantly influenced by overlying structures (fixed or removable prostheses); (2) histologic evidence of the remarkable regenerative capacity of the newly formed tissue that develops during healing by secondary intention; (3) clinical evidence that it is possible to guide the formation of this new regenerative tissue by creating a support with proper morphology and a highly polished surface; (4) observations that positive pressure exerted by alimentary bolus and negative pressure produced by deglutition affect the growth of this tissue healing by second intention; and (5) the application of appropriate oral hygiene techniques to guide tissue healing and maintain its integrity. The edentulous site enhancement approach is simple, practical, and predictable and offers minimal postoperative complications. This paper describes the edentulous site enhancement approach as applied in the pontic areas.

Morphogenic bone splitting: description of an original technique and its application in esthetically significant areas.

PURPOSE: This article presents a regenerative technique, morphogenic bone splitting (MBS), which overcomes the limitations associated with expansion techniques described to date. MATERIALS AND METHODS: The authors propose a method whereby the bone-mucosa-gingival complex (BMGC) is displaced in its entirety, establishing a new focus for a secondary hinge located in the coronal reaches of the osteotomy. Depending on clinical needs, this approach modifies or eliminates the facially inclined hinge displacement characteristic of ridge expansion techniques. By exploiting the inherent capacity for second intention healing, the regenerative MBS technique avoids the use of graft material, membranes, or mechanical devices. It effectively harnesses the intrinsic regenerative capabilities of the treated site. RESULTS AND CONCLUSIONS: The MBS technique is performed in a single operation. By permitting the insertion of implants of an appropriate size in the optimum position for esthetic and functional requirements, it achieves the desired 3-dimensional reshaping of the BMGC and thereby restores the anatomy of the implant site. This reshaping includes: root prominences, keratinized gingiva, papillae, fornix, and the mucogingival junction. In addition to these esthetically significant issues, it permits implants to be placed at a functionally favorable axial inclination.