Retrospective analysis of porcelain failures of metal ceramic crowns and fixed partial dentures supported by 729 implants in 152 patients: patient-specific and implant-specific predictors of ceramic failure.

STATEMENT OF PROBLEM: Porcelain fracture associated with an implant-supported, metal ceramic crown or fixed partial denture occurs at a higher rate than in tooth-supported restorations, according to the literature. Implant-specific and patient-specific causes of ceramic failure have not been fully evaluated. PURPOSE: The purpose of this retrospective study was to evaluate the potential statistical predictors for porcelain fracture of implant-supported, metal ceramic restorations. MATERIAL AND METHODS: Over a 6-month period, a consecutive series of patients having previously received implant-supported, metal ceramic fixed restorations were examined during periodic recall appointments. The number of supporting implants, number of dental units, type of restoration, date of prosthesis insertion, location in the dental arch, opposing dentition, type of occlusion, presence of parafunctional habits, use of an occlusal protective device, presence or absence of ceramic fractures, gender, and age were recorded for each patient. The generalized estimating equation (GEE) approach was used for the intrasubject correlated measurements analysis of categorical outcomes (presence or absence of ceramic fractures) to determine which patient- and implant-specific factors would predict porcelain fracture (alpha=.05). RESULTS: Data were collected from 152 patients representing 998 dental units (390 single crowns and 94 fixed partial dentures) supported by 729 implants. Porcelain fractures of 94 dental units occurred in 35 patients. The fractures were significantly (P<.05) associated with opposing implant-supported metal ceramic restorations, bruxism, and not wearing a protective occlusal device. Metal ceramic prostheses (single crown or fixed partial dentures) had approximately 7 times higher odds of porcelain fracture (odds ratio (OR)=7.06; 95% confidence interval (CI): 2.57 to 19.37) and 13 times greater odds of a fracture requiring either repair or replacement (OR=13.95; 95% CI: 2.25 to 86.41) when in occlusion with another implant-supported restoration, as compared to opposing a natural tooth. In addition, patients exhibiting bruxism or not wearing an occlusal device had approximately 7 times higher odds (OR=7.23; 95% CI: 3.86 to 13.54), and 2 times higher odds (OR=1.92; 95% CI: 1.01 to 3.67) of porcelain fracture when compared to patients without bruxism and patients not wearing an occlusal device. CONCLUSIONS: Implant-supported metal ceramic single crowns and fixed partial dentures were found to have a significantly higher risk of porcelain fracture in patients with bruxism habits, when a protective occlusal device was not used, and when the restoration opposed another implant-supported metal ceramic restoration.

A simplified method to develop optimal gingival contours for the single implant-supported, metal-ceramic crown in the aesthetic zone.

Prosthetic replacement of the missing single maxillary central incisor with an implant-supported crown represents a profound aesthetic challenge for the restorative dentist, laboratory technician, and surgeon. In addition to the visual fidelity of color, translucency, contour, and surface texture, the proper soft tissue outline is sacrosanct to the illusion of a natural tooth. The contrast between the uniformly round shoulder of the implant and the tooth's curvilinear cementoenamel junction is particularly problematic. This clinical report demonstrates a simplified method that precisely controls the facial gingival and proximal soft tissue contours for implant-supported, metal-ceramic crowns in the aesthetic zone, using the cervical anatomy of the maxillary incisor tooth as a guide. A new role for the provisional crown that is intended to maximize the volume of keratinized tissue is also described.

Retrospective analysis of 56 edentulous dental arches restored with 344 single-stage implants using an immediate loading fixed provisional protocol: statistical predictors of implant failure.

PURPOSE: The purpose of this retrospective study was to evaluate the effects of implant dimensions, surface treatment, location in the dental arch, numbers of supporting implant abutments, surgical technique, and generally recognized risk factors on the survival of a series of single-stage Straumann dental implants placed into edentulous arches using an immediate loading protocol. MATERIALS AND METHODS: Each patient received between 4 and 18 implants in one or both dental arches. Periapical radiographs were obtained over a 2- to 10-year follow-up period to evaluate crestal bone loss following insertion of the definitive metal-ceramic fixed prostheses. Univariate tests for failure rates as a function of age (< or = 59 years versus > or = 60 years), gender, smoking, bone grafting, dental arch, surface type, anterior versus posterior, number of implants per arch, and surgical technique were made using Fisher exact tests. The Cochran-Armitage test for trend was used to evaluate the presence of a linear trend in failure rates regarding implant length and implant diameter. Logistic regression modeling was used to determine which, if any, of the aforementioned factors would predict patient and implant failure. A significance criterion of P = .05 was utilized. RESULTS: Data were collected for 344 single-stage implants placed into 56 edentulous arches (39 maxillae and 17 mandibles) of 43 patients and immediately loaded with a 1-piece provisional fixed prosthesis. A total of 16 implants failed to successfully integrate, for a survival rate of 95.3%. Increased rates of failure were associated with reduced implant length, placement in the posterior region of the jaw, increased implant diameter, and surface treatment. Implant length emerged as the sole significant predictor of implant failure. CONCLUSION: In this retrospective analysis of 56 consecutively treated edentulous arches with multiple single-stage dental implants loaded immediately, reduced implant length was the sole significant predictor of failure.

Tissue-directed placement of dental implants in the esthetic zone for long-term biologic synergy: a clinical report.

Implant dentistry steadily evolves as more is learned about the unique biologic interrelationship of the dental implant restoration and the surrounding hard and soft tissues. Important factors include the impact of the surface microtopography on biochemically-mediated cell differentiation, the unavoidable bacterial colonization of the implant-abutment (or crown) microgap, the vertical and horizontal dimensions of biologic width, and the histology of surrounding structures. The recipient site, implant design, surgical technique, and location of the restorative platform significantly influence the optimal esthetics and biologic stability of implant restorations. There are differing opinions among clinicians regarding the appropriate positioning of the implant restorative platform in the vertical and sagittal planes relative to the alveolar crest. An apical and palatal orientation of the coronal platform relative to the alveolar crest in the esthetic zone is generally advocated for favorable facial and proximal emergence profiles of the definitive crown. Tissue-directed implant placement primarily considers the long-term consequences of the implant restoration upon the surrounding hard and soft tissues. The goal is to develop optimal gingival contours and a definitive restoration in the esthetic zone that coexist in stable biologic synergy. The rationale and the specific prosthodontic and surgical protocols inherent in the tissue-directed concept are discussed in this report.

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

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.

Development of gingival esthetics in the edentulous patient prior to dental implant placement using a flangeless removable prosthesis: a case report.

Development of gingival contours found in healthy natural dentitions enhances the esthetic results achieved with implant-supported fixed prostheses. However, this endeavor is frequently difficult to achieve, especially in the completely edentulous patient. Edentulous patients with optimal hard and soft tissue can be treated with a specially designed removable prosthesis that will develop gingival contours prior to implant placement. By means of a transitional complete removable prosthesis with ovate pontics and no labial flange, a natural-looking soft tissue profile can be developed prior to dental implant placement. A minimally invasive tissue punch surgical technique is used to place the implants, which are immediately restored with a 1-piece, cross-arch, provisional fixed prosthesis. This article presents the prosthodontic and surgical protocols utilized to improve the appearance of the definitive implant rehabilitation.

The use of a trephine biopsy needle to obtain autogenous corticocancellous bone from the iliac crest: technical note.

In the absence of adequate bone height, augmentation of the maxillary antrum prior to placement of endosseous implants is a well-established procedure. Although there is a debate among clinicians as to which grafting materials are the most advantageous, autogenous bone is still considered by many to be the gold standard. Often patients require more graft material than is generally available from intraoral sites. This has led clinicians to utilize allografts, xenografts, or a combination of autologous and synthetic bone. Extraoral sites can provide a greater volume of autogenous bone than intraoral sites. However, harvesting extraoral donor bone is frequently associated with adverse consequences in excess of the primary objective (i.e., the placement of endosseous implants in the posterior maxilla with minimal morbidity). A method for obtaining a significant volume of corticocancellous autogenous bone for augmentation of the maxillary antrum is described. The technique is efficacious and cost effective and results in minimal morbidity.