RESUMO
This study aimed to compare the surface characteristics and the shear bond strength of veneering porcelain of 3D printed 4Y-TZP with milled 4Y-TZP. Thirty disks with 10 mm diameter and 1.2 mm thickness were fabricated. Fifteen were fabricated by 3D printing (Experimental group), and another 15 by milling (Control group). In each group, five were assigned to surface analysis. Surface roughness was measured using a confocal laser microscope. Surface energy was calculated by measuring the contact angles of water and diiodo-methane with a drop-shape analyzer. Another ten specimens were used to evaluate the shear bonding strength of veneering porcelain on the surface of 4Y-TZP. The surface of 3D-printed 4Y-TZP was very smooth, and the surface roughness (Ra, Rq) was significantly lower than that of milled 4Y-TZP (p<0.001). 3D-printed 4Y-TZP showed low wettability compared with milled 4Y-TZP, i.e., the water contact angle was significantly high (p=0.008), and the surface free energy was low (p=0.008). The shear bond strength to veneered porcelain of 3D printed 4Y-TZP was significantly lower than that of milled 4Y-TZP (p<0.001). The surface characteristics of 4Y-TZP were quite different by the manufacturing process. The smooth surface and low wettability of 3D-printed 4Y-TZP could affect its low shear bonding strength to veneering porcelain.
RESUMO
PURPOSE: The aim of this study was to investigate the effects of a titanium component for the zirconia abutment in the internal connection implant system on screw loosening under thermocycling conditions. MATERIALS AND METHODS: Internal connection titanium abutments and external connection zirconia abutments with titanium sockets were connected respectively to screw-shaped internal connection type titanium implants with 30 Ncm tightening. These implant-screw-abutment assemblies were divided into two groups of five specimens each; titanium abutments as control and zirconia abutments with titanium sockets as experimental group. The specimens were subjected to 2,000 thermocycles in water baths at 5℃ and 55℃, with 60 seconds of immersion at each temperature. The removal torque values (RTVs) of the abutment screws of the specimen were measured before and after thermocycling. RTVs pre- and post-thermocycling were investigated in statistics. RESULTS: There was not screw loosening identified by tactile and visual inspection in any of the specimens during or after thermocycling. The mean RTV difference for the control group and the experimental group were -1.34 ± 2.53 Ncm and -1.26 ± 2.06 Ncm, respectively. Statistical analysis using an independent t-test revealed that no significant differences were found in the mean RTV difference of the groups (P > 0.05). CONCLUSION: Within the limitations of this in vitro study, the titanium socket for the zirconia abutment did not show a significant effect on screw loosening under thermal stress compared to the titanium abutment in the internal connection implant.
Assuntos
Banhos , Imersão , Técnicas In Vitro , Titânio , Torque , ÁguaRESUMO
OBJECTIVES: We aimed to evaluate the effectiveness of Er:Cr:YSGG laser therapy on the reduction of dentinal hypersensitivity while taking into account the length and depth of the cervical abrasion. METHODS: We included adults (age, 20-60 years) with at least 2 hypersensitive teeth. The hypersensitive teeth were stimulated with a pressure-indicating probe and an air syringe. The response of the subjects to this stimulation was quantified using a visual analog scale (VAS) and Schiff air sensitivity score. The patients were treated at baseline, immediately after laser treatment, and at 1, 2, and 4 weeks after the Er:Cr:YSGG laser therapy. The results were analyzed by repeated measure analysis of variance (ANOVA) and Bonferroni's post hoc test. RESULTS: The values of tactile test and air blast test showed statistically significant differences between the following time points: baseline and immediately after laser treatment, baseline and first week after treatment, and immediately after laser treatment and first week after treatment (P0.05). The depth and width of the cervical abrasion was not statistically significant in dentinal hypersensitivity reduction (P>0.05). CONCLUSIONS: The use of Er:Cr:YSGG laser therapy reduced dentinal hypersensitivity, especially immediately after laser treatment. The depth and width of the cervical abrasion is not statistically significant in dentinal hypersensitivity reduction.
Assuntos
Adulto , Humanos , Dentina , Hipersensibilidade , Terapia a Laser , Seringas , DenteRESUMO