An In Vivo Evaluation of the Fit of Zirconium-Oxide Based, Ceramic Single Crowns with Vertical and Horizontal Finish Line Preparations.

PURPOSE: Different types of tooth preparations influence the marginal precision of zirconium-oxide based ceramic single crowns. In this in vivo study, the marginal fits of zirconium-oxide based ceramic single crowns with vertical and horizontal finish lines were compared. MATERIALS AND METHODS: Forty-six teeth were chosen in eight patients indicated for extraction for implant placement. CAD/CAM technology was used for the production of 46 zirconium-oxide-based ceramic single crowns: 23 teeth were prepared with vertical finishing lines, 23 with horizontal finishing lines. One operator accomplished all clinical procedures. The zirconia crowns were cemented with glass ionomer cement. The teeth were extracted 1 month later. Marginal gaps along vertical planes were measured for each crown, using a total of four landmarks for each tooth by means of a microscope at 50× magnification. On conclusion of microscopic assessment, ESEM evaluation was completed on all specimens. The comparison of the gap between the two types of preparation was performed with a nonparametric test (two-sample Wilcoxon rank-sum test) with a level of significance fixed at p < 0.05. All data were analyzed with STATA12. RESULTS: In the group with horizontal finish line preparations, the median value of the gap was 35.45 µm (Iqr, 0.33); for the vertical finish line group, the median value of the gap was 35.44 µm (Iqr, 0.40). The difference between the two groups was not statistically significant (two-sample Wilcoxon rank-sum test, p = 0.0872). CONCLUSIONS: Within the limitations of this study, the gaps of the zirconium-oxide-based ceramic CAD/CAM crowns with vertical and horizontal finish line preparations were not different.

Prosthetic procedure for simultaneous immediate loading of opposing edentulous arches.

For patients with complete edentulism, a significant problem is the transfer of diagnostic data to the definitive casts when an immediate loading technique is used. This article presents a prosthetic procedure to allow simultaneous treatment of opposing edentulous arches with immediate implant loading. This technique uses 2 occlusal acrylic resin devices to transfer the diagnostic cast information to the definitive casts. Esthetic and functional fixed dental prostheses are fabricated from diagnostic information acquired in the presurgical phase without any impression or recording of the maxillomandibular relationship during or after surgery. This methodology is applicable when the simultaneous immediate loading of implants in 2 edentulous arches is indicated.

An in vivo evaluation of fit of zirconium-oxide based ceramic single crowns, generated with two CAD/CAM systems, in comparison to metal ceramic single crowns.

PURPOSE: The purpose of this study was to assess in vivo the marginal fit of single crowns produced using two CAD/CAM all-ceramic systems, in comparison to more traditional metal ceramic crowns. MATERIALS AND METHODS: Thirty vital, caries-free, and previously untreated teeth were chosen in five patients who needed extraction for implant placement and therefore were included in this study. In the control group (C), 10 regular metal ceramic crowns with porcelain occlusal surfaces were fabricated. In the other two groups (Z and E), CAD/CAM technology was used for the fabrication of 20 zirconium-oxide-based ceramic single crowns with two systems. All zirconia crowns were cemented with glass-ionomer cement, always following the manufacturer's instructions. The same dentist carried out all clinical phases. The teeth were extracted 1 month later. Marginal gaps along vertical planes were measured for each crown, using a total of four landmarks for each tooth by means of a microscope at a magnification of 50×. On completion of microscopic evaluation, representative specimens from each group were prepared for ESEM evaluation. Mean and standard deviations of the four landmarks (mesial, distal, buccal, palatal) at each single crown were calculated for each group. Multivariate analysis of variance (MANOVA) was performed to determine whether the four landmarks, taken into consideration together, differed between groups. Two-way ANOVA was performed to study in detail, for each landmark, how the three systems used to produce the FPDs affected the gap measurements. Differences were considered to be significant at p < 0.05. RESULTS: MANOVA revealed no quantitative differences of the four landmarks, when taken into consideration together, between the three groups (p < 0.0001). Two-way ANOVA, performed at each landmark, revealed no quantitative differences between the three groups (p < 0.0001 for each landmark). CONCLUSIONS: Within the limitations of this study, it was concluded that the two zirconium-oxide-based ceramic CAD/CAM systems demonstrated a similar and acceptable marginal fit when compared to more traditional metal ceramic crowns.

A human histologic report of an implant placed with simultaneous sinus floor elevation without bone graft.

A titanium implant with an acid-etched surface was placed simultaneously with sinus floor elevation in a severely resorbed ridge of a 52-year-old man. The height of the residual crest was less than 3 mm, and no bone substitute was used to graft the sinus cavity. Six months after placement, the implants were uncovered, and no signs of mobility were recorded. The implant at the second molar site and surrounding bone were removed for prosthetic convenience. The specimen was harvested and processed for undecalcified histologic analysis. Poor bone quality around the implant was evident, characterized by large marrow spaces and scarce trabeculation. Signs of osseointegration could be seen mainly toward the apical third of the implant. A cortical wall was present apical to the implant, suggesting the formation of a new sinus floor. The relationship between the histologic evidence and possible clinical implications are discussed.

The one-model technique: a new method for immediate loading with fixed prostheses in edentulous or potentially edentulous jaws.

This article examines a new prosthetic procedure for the immediate loading of implants with a fixed prosthesis in edentulous or potentially edentulous arches. In these situations, one of the main problems associated with immediate loading is the transfer of diagnostic information to the master cast. This technique takes advantage of an acrylic resin transfer plate that enables transfer of the study cast information to the master cast. Without any intrasurgical impression or any recording of the maxillomandibular relationship during or after surgery, construction of an adequate esthetic and functional fixed prosthesis is possible on the basis of diagnostic information acquired in the presurgical phase. The methodology is always applicable when there is an indication for immediate loading of implants. The rationale and guidelines for the successful use of this technique in edentulous or potentially edentulous arches are discussed and illustrated with a clinical case.