Inter- and intraindividual variability in virtual single-tooth implant positioning.

OBJECTIVES: The purpose of this prospective study was to determine the inter- and intraindividual variability in virtual single-tooth implant positioning based on the level of expertise, specialty, total time spent, and the use of a prosthetic tooth setup. MATERIALS AND METHODS: Virtual implant planning was performed on matched pre- and post-extraction intraoral scans (IOS), and cone-beam computed tomography scans of 15 patients. Twelve individual examiners, involving six novices and experts from oral surgery and prosthodontics positioned the implants, first based on anatomical landmarks utilizing only the post-extraction, and second with the use of the pre-extraction IOS as a setup. The time for implant positioning was recorded. After 1 month, all virtual plannings were performed again. The individual implant positions were superimposed to obtain 3D deviations using a software algorithm. RESULTS: An interindividual variability with mean angular, crestal, and apical positional deviations of 3.8 ± 1.94°, 1.11 ± 0.55, and 1.54 ± 0.66 mm, respectively, was found. When assessing intraindividual variability, deviations of 3.28 ± 1.99°, 0.78 ± 0.46, and 1.12 ± 0.61 mm, respectively, were observed. Implants planned by experts exhibited statistically lower deviations compared to those planned by novices. Longer planning times resulted in lower deviations in the experts' group but not in the novices. Oral surgeons demonstrated lower crestal, but not angular and apical deviations than prosthodontists. The use of a setup only led to minor adjustments. CONCLUSIONS: Substantial inter- and intraindividual variability exists during implant positioning utilizing specialized software planning. The level of expertise and the time invested influenced the deviations of the implant position during the planning sequence.

Repair bond strength of resin composite to restorative materials after short- and long-term storage.

OBJECTIVES: To investigate short- and long-term bond strength ("repair bond strength"; RBS) of a resin composite to six restorative materials using either a silane and a bonding agent or a universal "one-step self-etch" adhesive system. METHODS: Specimens were produced from an amalgam, a direct resin composite, two indirect resin composites, a hybrid ceramic, and a feldspar ceramic and stored for 3 months in tap water (37 °C). All specimens were then sandblasted (Al2O3; 25 µm) and either treated with Monobond Plus and OptiBond FL Adhesive (MP-OFL) or with Scotchbond Universal (SBU). Filtek Z250 was used as "repair composite", and RBS was measured by means of a micro shear bond strength test after 24 h or after 1 year. RBS values (n = 15/group) were statistically analyzed (α = 0.05). RESULTS: RBS (MPa; mean values (standard deviations)) after 24 h for MP-OFL: 18.6 (3.2)-23.9 (5.0) and for SBU: 12.5 (4.9)-18.1 (4.6); after 1 year for MP-OFL: 8.9 (4.6)-19.8 (4.3) and for SBU: 5.6 (2.3)-18.8 (3.5). After 24 h, MP-OFL showed significantly higher RBS to the hybrid ceramic and the feldspar ceramic than did SBU (p ≤ 0.0001) whereas there was no significant difference in RBS for the other four restorative materials. After 1 year, MP-OFL showed significantly higher RBS to the feldspar ceramic than did SBU (p = 0.043) whereas there was no significant difference in RBS for the other five restorative materials. SIGNIFICANCE: The use of a silane and a bonding agent seems more versatile for repairing restorations than the use of a universal "one-step self-etch" adhesive system.