Survival Rate, Fracture Strength and Failure Mode of Ceramic Implant Abutments After Chewing Simulation

The aim of this study was to compare titanium-reinforced ZrO2 and pure Al2O3 abutments regarding their outcome after chewing simulation and static loading. Forty-eight standard diameter implants with an external hexagon were divided into three groups of 16 implants each and restored with three different types of abutments (group A: ZrO2 abutments with titanium inserts; group B: densely sintered high-purity Al2O3 abutments; group C: titanium abutments). All abutments were fixated on the implants with gold-alloy screws at 32 Ncm torque, and metal crowns were adhesively cemented onto the abutments. The specimens were exposed to 1.2 million cycles in a chewing simulator. Surviving specimens were subsequently loaded until fracture in a static testing device. Fracture loads (N) and fracture modes were recorded. A Wilcoxon Rank test to compare fracture loads among the 3 groups and a Fisher exact test to detect group differences in fracture modes were used for statistical evaluation (

Influence of different maintenance times of torque application on the removal torque values to loosen the prosthetic abutment screws of external hexagon implants

PURPOSE: To analyze the torque application on prosthetic abutment screws using different maintenance times, to determine an influence on the removal torque values. MATERIALS AND METHODS: A total of 40 external hexagon implants, 40 titanium screws, and 40 customized abutments were used. In group 1, the screws received a torque of 30 N·cm by instant torque application; in groups 2, 3, and 4, torque of 30 N·cm was applied and maintained for 10, 20, and 30 seconds, respectively. Removal torque was performed 10 minutes after torque application. Data were statistically analyzed using 1-way ANOVA and Tukey HSD test (α = 0.05). RESULTS: The mean and standard deviation (±SD) of removal torque values found were 11.61 ± 1.43 N·cm for group 1; 18.64 ± 1.71 N·cm for group 2; 21.62 ± 0.97 N·cm for group 3; and 21.48 ± 1.55 N·cm for group 4. Groups 3 and 4 exhibited statistically higher values than group 2, which demonstrated significantly higher values than group 1 (P < 0.05). CONCLUSIONS: A torque of 30 N·cm applied for 20 seconds seemed to be the best option when considering the removal torque values of external hexagon implants

Randomized-controlled clinical trial of customized zirconia and titanium implant abutments for single-tooth implants in canine and posterior regions: 3-year results

Objectives: The aim was to test whether or not zirconia abutments exhibit the same survival and technical / biological outcome as titanium abutments. Material and methods: Twenty-two patients receiving 40 single-tooth implants in canine and posterior regions were included. The implant sites were randomly assigned to 20 zirconia and 20 titanium abutments. All-ceramic and metal-ceramic crowns were fabricated. At baseline, 6, 12 and 36 months, the reconstructions were examined for technical and biological problems. Probing pocket depth (PPD), plaque control record (PCR) and bleeding on probing (BOP) were assessed at abutments (test) and analogous contralateral teeth (control). Standardized radiographs of the implants were made and the bone level (BL) was measured referring to the implant shoulder on mesial (mBL) and distal sides (dBL). The difference of color (DeltaE) of the peri-implant mucosa and the gingiva of control teeth was assessed with a spectrophotometer. The data were statistically analyzed with Mann-Whitney Rank and Student's unpaired t-tests. Results: Eighteen patients with 18 zirconia and 10 titanium abutments were examined at a mean follow-up of 36 months (range 31.5-53.3 months). No fracture of an abutment or loss of a reconstruction was found. Hence, both exhibited 100% survival. At two metal-ceramic crowns supported by titanium abutments chipping of the veneering ceramic occurred. No difference of the biological outcome of zirconia and titanium abutments was observed: PPD ( 3.2 +/- 1 mm, mPPD(Ti) 3.4 +/- 0.5 mm), PCR ( 0.1 +/- 0.2, mPCR(Ti) 0.1 +/- 0.2) and BOP ( 0.4 +/- 0.4, mBOP(Ti) 0.2 +/- 0.3). Furthermore, the BL was similar at implants supporting zirconia and titanium abutments ( 1.7 +/- 1, 1.6 +/- 1; mBL(Ti) 2 +/- 1, dBL(Ti) 2.1 +/- 1). Both, zirconia and titanium abutments induced a similar amount of discoloration of the mucosa compared with the gingiva at natural teeth ( 9.3 +/- 3.8, DeltaE(Ti) 6.8 +/- 3.8). Conclusions: At 3 years, zirconia and titanium abutments exhibited same survival and technical, biological and esthetical outcomes. To cite this article: Zembic A, Sailer I, Jung RE, Hämmerle CHF. Randomized-controlled clinical trial of customized zirconia and titanium implant abutments for single-tooth implants in canine and posterior regions: 3-year results. Clin. Oral Impl. Res. xx, 2009; 000-000