Clinical performance of tooth- or implant-supported veneered zirconia single crowns: 42-month results.

OBJECTIVES: The objective of this clinical study was to compare and assess the clinical performance of tooth-supported and implant-supported zirconia single crowns with sintered veneering caps. METHODS: In this prospective study, 118 patients with a total of 220 single crowns placed on 106 teeth (69 vital teeth, 37 endodontically treated teeth) and 114 implants in molar and premolar regions were examined during a mean observation period of 42 months. The restorations were evaluated for technical failures such as veneering porcelain fractures (chipping), surface quality, marginal fit, and the interface quality of the coping and sintered veneering. The soft tissue status was assessed using the modified Silness and Löe's plaque and gingival index (mPI) and the modified Muhlemann sulcus bleeding index (mSBI). Tooth-supported crowns were checked for secondary caries and hypersensitivity during the follow-up period. Recalls were performed every 6 months. RESULTS: The 3-year Kaplan-Meier success probability was 98.2% and 100% for implant- and tooth-supported crowns, respectively. A significant difference could be detected between the implant-supported and tooth-supported zirconia single crowns, in terms of their chipping rate (p = 0.039). Veneering material fractures were recorded on two implant-supported restorations (1.8%). No veneering fractures occurred on tooth-supported single crowns. The plaque and gingival index and sulcus bleeding index showed stable and healthy soft peri-implant and periodontal tissues. Neither loss of vitality nor secondary caries occurred on tooth-supported crowns. CONCLUSIONS: Zirconia-based single crowns with a sintered veneering cap showed promising clinical results on both tooth and implant abutments; however, the dental implants were more prone to complications. In terms of clinical significance, high-strength ceramic with a sintered veneering cap can be recommended for prosthetic treatment of both tooth- and implant-supported single crowns in molar regions. CLINICAL RELEVANCE: This study provides valuable information for further application of all-ceramic restorations.

Clinical performance of screw-retained and cemented implant-supported zirconia single crowns: 36-month results.

OBJECTIVES: The objective of this clinical study was to evaluate the clinical performance of implant-supported zirconia crowns with a sintered veneering cap. Furthermore, the influence of the type of retention (screw-retained vs cemented single crowns) was analysed. MATERIALS AND METHODS: Fifty-eight patients were accommodated with 114 implants, inserted in the molar and premolar regions. Zirconia-based crowns with a sintered veneering cap were either screw-retained (n = 53) or cemented (n = 61) on the implant. Recalls were performed every 6 months. The state of soft tissue was documented by the modified plaque and gingiva index (mPI) and sulcus bleeding index (mSBI). The restorations were evaluated for technical failures like veneering porcelain fractures, surface qualities and marginal fitting. RESULTS: Neither implant loss nor crown fractures occurred. After a mean clinical service time of 36.9 months, fractures of the veneering porcelain were registered in 1.8 % of the cases. The Kaplan-Meier survival probability regarding eventless restorations was 98.2 %. Chipping of the veneering porcelain was registered in two cemented crowns without statistical influence of the type of retention. The indices showed healthy soft periimplant tissues in both groups. CONCLUSIONS: Implant-supported zirconia crowns with a sintered veneering cap demonstrated good clinical performance. The type of retention had no influence on technical complications.

Innovative Single-Tooth Replacement with an Individual Root-Analog Hybrid Implant in the Esthetic Zone: Case Report.

The goal of this study was to explore an innovative approach to single-tooth replacement using an individually custom-fabricated, root-analog, hybrid dental implant, in the esthetic zone, to avoid the microgap and micromovements between the implant and abutment. Moreover, the use of burs to prepare the implant recipient site is not necessary in this technique, reducing the bone removal, heating, and trauma. The process requires capturing accurate root geometry through combined computer-aided design/computer-assisted manufacturing (CAD/CAM) and a three-dimensional (3D) visualization (digital volume tomography [DVT]) of the tooth in situ, which might result in reduced remodeling after insertion. A good esthetic and functional outcome was obtained. The use of a root-shaped tooth analog implant might be in selected cases a viable alternative to current threaded cylindrical and cone-shaped implants. The new concept avoids the microgap between the implant and the abutment and reduces the trauma to the tissue and bone.

The predictors of implant failure after maxillary sinus floor augmentation and reconstruction: a retrospective study of 1045 consecutive implants.

OBJECTIVE: To assess the predictors of implant failure after grafted maxillary sinus (GMS). MATERIAL AND METHODS: A total of 1045 implants were inserted in 224 patients/347 GMS during a period of 14 years. Kaplan-Meyer and multivariate log-regression analysis were used to assess the following variates: patient's age, gender, smoker/nonsmoker, American Society of Anesthesiologists (ASA) class, one/two-stage surgery, merged/submerged healing, membrane, antibiotics, auto/allo/xenogenic bone grafts, implant's lengths/surface/diameter, crestal bone atrophy/quality, implant region, prosthetics, opposing dentition, and implant proximity to evaluate the predictors and relative risk (hazard ratio [HR]) of implant failure. RESULTS: Significant implant failure predictors were the graft material (HR = 4.7), with superior results for autogenic bone, residual crestal bone height (HR = 3.51), ASA class (HR = 2.73), surgical technique (HR = 2.56), implant proximity (HR = 2.07), smoker (HR = 1.98), and age (>60/HR=1.39). All other factors were insignificant. Overall survival rate was 93.3%. CONCLUSIONS: GMS is effective when the predictors are considered. Patient selection, including the ASA status, smoking, residual bone height, and the graft material are the predominant predictors. In highly atrophic situations, autogenic bone grafts showed superiority; however, in less atrophic cases, nonautogenic bone-grafts are equivalent.