Aim of the investigation was to assess the effect of different surface treatments on the bond strength of veneering ceramics to zirconia. In a shear test, the influences of polishing, sandblasting, and silica-coating of the zirconia surface on bonding were assessed with five different veneering ceramics. In addition the effect of liner application was examined. With one veneering ceramic, the impact of regeneration firing of zirconia was also evaluated. Statistical analysis was performed with one-way ANOVA and post hoc Scheffé's test. Failure in every case occurred in the veneering ceramic adjacent to the interface with a thin layer of ceramic remaining on the zirconia surface, indicating that bond strength was higher than the cohesive strength of the veneering ceramic. Shear strength ranged from 23.5±3.4MPa to 33.0±6.8MPa without explicit correlation to the respective surface treatment. Regeneration firing significantly decreased the shear strength of both polished and sandblasted surfaces. Findings of this study revealed that bonding between veneering ceramics and zirconia might be based on chemical bonds. On this note, sandblasting was not a necessary surface pretreatment to enhance bond strength and that regeneration firing was not recommended.

For implant-supported FAFDPs, using 4-6 implants is a well-documented treatment option with high estimated 5-year survival of the construction. It is unclear whether three implants for supporting a FAFDP will achieve similar survival rates. The RCTs needed that report implant-to-replaced-units-ratios for partial FDPs and include 3 vs. 4-6 implants for supporting a FAFDP in the mandible.

Aim: The aim of this clinical trial was to evaluate the safety and efficiency of a one-piece zirconia

OBJECTIVE: The aim of this in-vitro study was to compare the tolerance of surgical instruments in surgical guides produced by 3-D printing, without metal sleeves to a surgical guide with conventional metal sleeves from two different manufacturers. MATERIALS AND METHODS: Lateral movements of drill tips caused by tolerance between the sleeve and drill key and between the drill key and the drill were recorded after application of a standardized force to the surgical instruments. Four groups were tested: Control 1 (C1): metal sleeve from commercially available surgical system 1; Test 1 (T1): 3-D-printed sleeve for surgical system 1; Control 2 (C2): metal sleeve from commercially available surgical system 2. Test 2 (T2): 3-D-printed sleeve for surgical system 2. RESULTS: The mean total lateral movement was 0.75 mm (0.5-1.04 mm) in the C1 group and 0.91 mm (0.54-1.34 mm) in the C2 group. The mean amount of movement from tolerance between sleeve and drill-guiding key was 0.31 mm (range 0.22-0.41 mm) in C1 and 0.42 mm (range 0.29-0.56 mm) in C2. This lateral movement was in mean reduced by 0.24 mm (32%) in T1 and by 0.39 mm (43%) in T2 group. This reduction was statistically significant in both groups (P < 0.001). CONCLUSION: The tolerance of surgical instruments and the lateral movements of the drills were significantly reduced by the use of 3-D printing with reduced sleeve diameter. This reduction could improve the overall accuracy in computer-assisted template-guided implant dentistry. The lateral movement of the drill can be further reduced by using a shorter drill and a higher drill key. This can be considered during implant planning and CAD/CAM of surgical guides. AbstractObjective: The aim of this in-vitro study was to compare the tolerance of surgical instruments in surgical guides produced by 3D printing, without metal sleeves to a surgical guide with conventional metal sleeves from two different manufacturers. Materials and methods:Lateral movements of drill tips caused by tolerance between the sleeve and drill key and between the drill key and the drill were recorded after application of a standardized force to the surgical instruments. Four groups were tested: Control 1 (C1):Metal sleeve from commercially available surgical system 1; Test 1 (T1): 3D-printed sleeve for surgical system 1; Control 2 (C2): Metal sleeve from commercially available surgical system 2. Test 2 (T2): 3D-printed sleeve for surgical system 2. Results:The mean total lateral movement was 0.75mm (0.5 to 1.04mm) in the C1 group and 0.91mm (0.54 to 1.34mm) in the C2 group. The mean amount of movement from tolerance between sleeve and drill-guiding key was 0.31mm (range 0.22 to 0.41mm) in C1 and 0.42mm (range 0.29 to 0.56mm) in C2. This lateral movement was in mean reduced by 0.24mm (32%) in T1 and by 0.39mm (43%) in T2 group. This reduction was statistically significant in both groups (p<0.001). Conclusion:The tolerance of surgical instruments and the lateral movements of the drills were significantly reduced by the use of 3D prin...