Originally published at: Özcan, Mutlu; Lamperti, Sofia (2015). Effect of mechanical and air-particle cleansing protocols of provisional cement on immediate dentin sealing layer and subsequent adhesion of resin composite cement. Journal of Adhesion Science and Technology, 29(24) Zürich, 2 Abstract: Immediate dentin sealing (IDS) could avoid contamination of dentin from impression material and provisional cement but prior to final cementation of indirect restorations, removal of the provisional cement may damage the IDS. The objectives of this study were to investigate the effect of mechanical and air-particle cleansing protocols of provisional cement on IDS layer and subsequent adhesion of resin composite cement. The cuspal dentin surfaces of human third molars (N=18, n quadrant =72) were exposed by a low speed diamond saw under water cooling and conditioned with an adhesive system based on 3-step etch and rinse technique (OptiBond FL). Provisional cement (Freegenol) was applied on each specimen.They were then randomly divided into 6 subgroups where the provisional cement was removed either by 1)Air-borne particle abrasion with 50 µm Al 2 O 3 particles at 2 bar (AL2), 2) Air-borne particle abrasion with 50µm Al 2 O 3 particles at 3.5 bar (AL3.5), 3) Air-borne particle abrasion with 30 µm SiO 2 particles at 2 bar (SL2), 4) Air-borne particle abrasion with 30 µm SiO 2 particles at 3.5 bar (SL3.5), 5) Prophylaxy paste (Cleanic) (PP) or 6) Pumice-water slurry (PW) at 1500 rpm for 15 s. The dentin surface on each tooth was assigned to 4 quadrants and each quadrant received the cleansing methods in a clockwise sequence. The non-contaminated and non-cleansed teeth acted as the control (N=3, n quadrant =12) (C). Two separate teeth, contaminated and cleansed according to 6 cleansing protocols, were allocated for Scanning Electron Microscopy (SEM) analysis (x2000). The dentin surfaces in each quadrant received resin composite luting cement (Variolink II, Ivoclar Vivadent) incrementally in a polyethylene mould (diameter: 1 mm 2 ; height: 4 mm) and photo-polymerized. The specimens were stored in distilled water for 24 hours at 37ºC until the testing procedures and then shear force was applied to the adhesive interface until failure occurred in a Universal Testing Machine (0.5 mm/min). Microshear bond (µSBS) was calculated by dividing the maximum load (N) by the bonding surface area of the resin cement. Failure types were analyzed using optical microscope and SEM. Data (MPa) were analyzed using one-way ANOVA (α=0.05). Two-parameterWeibull distribution values including the Weibull modulus, scale (m) and shape ( 0 ), values were calculated.Mean µSBS results (MPa) showed significant difference between the experimental groups (P=0.011) and were in descending order as follows: C (8±2. dentin and the adhesive resin, which is a combination of adhesive and cohesive failure in the adhesive resin. Cohesive failure in the dentin was not observed in any of the groups. Weibull distribution presented lower shape ( 0 ) for C (3.9), AL2 (3...

Objectives To compare cemented and screw‐retained one‐piece zirconia‐based restorations in terms of clinical, radiographic, and technical outcomes 5 years after insertion. Materials and methods Thirty‐four patients with single‐tooth implants were randomly restored with either a cemented lithium disilicate crown on a one‐piece customized zirconia abutment (CEM, 17 patients) or a screw‐retained crown based on a directly veneered one‐piece customized zirconia abutment (SCREW, 16 patients). All patients were recalled for a baseline examination (7–10 days after crown insertion) and then annually up to 5 years. The following outcomes were assessed: marginal bone level (changes), technical, and clinical (bleeding on probing, plaque control record, probing depth, and keratinized tissue) parameters. The Mann–Whitney U‐test was used to assess differences between the two groups. Results At 5 years, 26 patients (13 in each group) were re‐examined. The survival rates on the implant and restorative levels were 100% and 82.4% (equally for both groups), respectively. At 5 years, the median marginal bone level was located at −0.15 mm (IQR: −0.89 mm; 0.27 mm) (CEM) and −0.26 mm (IQR: −0.38 mm; 0.01 mm) (SCREW) below the implant shoulder (intergroup p = .9598). The median changes between baseline and the 5‐year follow‐up amounted to −0.23 mm (CEM; intragroup p = .0002) and −0.15 mm (SCREW; intragroup p = .1465) (intergroup p = .1690). The overall technical complication rate at 5 years was 15.4% (CEM) and 15.4% (SCREW) (intergroup p = 1.00). Clinical parameters remained stable over time (baseline to 5 years). Conclusions At 5 years, screw‐retained and cemented restorations rendered largely the same clinical, technical, and radiographic outcomes. Technical complications were frequent in both groups.