ABSTRACT
PURPOSE: To evaluate the effects of different abutment geometries in combination with varying luting agents and the effectiveness of different cleaning methods (prior to re-cementation) regarding the retentiveness of zirconia copings on implants. MATERIALS AND METHODS: Implants were embedded in resin blocks. Three groups of titanium abutments (pre-fabricated, height: 7.5 mm, taper: 5.7degrees; customized-long, height: 6.79 mm, taper: 4.8degrees; customized-short, height: 4.31 mm, taper: 4.8degrees) were used for luting of CAD/CAM-fabricated zirconia copings with a semi-permanent (Telio CS) and a provisional cement (TempBond NE). Retention forces were evaluated using a universal testing machine. Furthermore, the influence of cleaning methods (manually, manually in combination with ultrasonic bath or sandblasting) prior to re-cementation with a provisional cement (TempBond NE) was investigated with the pre-fabricated titanium abutments (height: 7.5 mm, taper: 5.7degrees) and SEM-analysis of inner surfaces of the copings was performed. Significant differences were determined via two-way ANOVA. RESULTS: Significant interactions between abutment geometry and luting agent were observed. TempBond NE showed the highest level of retentiveness on customized-long abutments, but was negatively affected by other abutment geometries. In contrast, luting with Telio CS demonstrated consistent results irrespective of the varying abutment geometries. Manual cleaning in combination with an ultrasonic bath was the only cleaning method tested prior to re-cementation that revealed retentiveness levels not inferior to primary cementation. CONCLUSION: No superiority for one of the two cements could be demonstrated because their influences on retentive strength are also depending on abutment geometry. Only manual cleaning in combination with an ultrasonic bath offers retentiveness levels after re-cementation comparable to those of primary luting.
Subject(s)
Baths , Cementation , Dental Cements , Titanium , UltrasonicsABSTRACT
OBJECTIVE: The purpose of this study was to evaluate, by shear bond strength (SBS) testing, the influence of different types of temporary cements on the final cementation using conventional and self-etching resin-based luting cements. Material and Methods: Forty human teeth divided in two halves were assigned to 8 groups (n=10): I and V (no temporary cementation); II and VI: Ca(OH)2-based cement; III and VII: zinc oxide (ZO)-based cement; IV and VIII: ZO-eugenol (ZOE)-based cement. Final cementation was done with RelyX ARC cement (groups I to IV) and RelyX Unicem cement (groups V to VIII). Data were analyzed statistically by ANOVA and Tukey's test at 5 percent significance level. RESULTS: Means were (MPa): I - 3.80 (±1.481); II - 5.24 (±2.297); III - 6.98 (±1.885); IV - 6.54 (±1.459); V - 5.22 (±2.465); VI - 4.48 (±1.705); VII - 6.29 (±2.280); VIII - 2.47 (±2.076). Comparison of the groups that had the same temporary cementation (Groups II and VI; III and VII; IV and VIII) showed statistically significant difference (p<0.001) only between Groups IV and VIII, in which ZOE-based cements were used. The use of either Ca(OH)2-based (Groups II and VI) or ZO-based (Groups III and VII) cements showed no statistically significant difference (p>0.05) for the different luting cements (RelyX TM ARC and RelyX TM Unicem). The groups that had no temporary cementation (Groups I and V) did not differ significantly from each other either (p>0.05). CONCLUSION: When temporary cementation was done with ZO- or ZOE-based cements and final cementation was done with RelyX ARC, there was an increase in the SBS compared to the control. In the groups cemented with RelyX Unicem, however, the use of a ZOE-based temporary cement affected negatively the SBS of the luting agent used for final cementation.
Subject(s)
Humans , Dental Bonding , Dental Cements/chemistry , Acid Etching, Dental , Aluminum Silicates/chemistry , Bisphenol A-Glycidyl Methacrylate/chemistry , Cementation , Calcium Hydroxide/chemistry , Dentin , Dental Porcelain/chemistry , Dental Stress Analysis/instrumentation , Eugenol/chemistry , Materials Testing , Polyethylene Glycols/chemistry , Polymethacrylic Acids/chemistry , Potassium Compounds/chemistry , Resin Cements/chemistry , Shear Strength , Stress, Mechanical , Temperature , Time Factors , Water/chemistry , Zinc Oxide-Eugenol Cement/chemistry , Zinc Oxide/chemistryABSTRACT
STATEMENT OF PROBLEM: Long-term exposure of dental porcelain to saliva during temporary cementation of a porcelain-fused to metal (PFM) restoration could affect mechanical strength of dental porcelain if the restoration is refired. PURPOSE: This work was performed to verify the effect of water on the mechanical strength in aged dental porcelain. MATERIAL AND METHOD: 63 specimens(Vintage Metalbond opaque and opal powder) were distributed to three experimental groups; non-water immersed control, immersed and pedried, and immersed and non-predired groups. The changes in flexural strength and fracture toughness after specimen refiring related to Fourier Transform Infrared (FT-IR) spectroscopy. RESULTS: 1. The FT-IR reflectances assigned to molecular bonds of H2O were noted as significantly different between the first-fired group and three refired groups and between two water-immersed groups and control group after refiring( p<0.05). They were also significantly different between predried group and non-predried group after refiring( p<0.05). 2. For opal specimens, FT-IR absorbances for hydrogen bond of H2O and silanols were significantly higher in non-predried group than in predreid group( p<0.05). 3. Predried opal group showed the highest mean flexural strength( p<0.05). Non-predried group indicated higher mean flexural strength than control group( p<0.05). 4. The mean fracture toughness for predired group was higher than non-predried group( p<0.05). 5. The difference of leucite crystal size is noted between control group and water-immersed, predried group in scanning electron microscopic study(x10000).