Comparison of autoclave and microwave postpolymerization treatments on flexural strength of hard reline resins

Amaç: Otoklav ve mikrodalga post-polimerizasyon uygulamalarının sert besleme akriliği ve ısı ile polimerize olan akriliğin bükülme direnci üzerine etkisinin karşılaştırılması. Gereç ve Yöntem: Sert besleme akriliği ve ısı ile polimerize olan akrilik malzemeden 64x10x3.3 mm boyutunda örnekler hazırlandı. Her iki akrilikten 80 adet örnek hazırlandı ve 4 alt gruba ayrıldı (n=20). Örnekler, mikrodalga ve otoklavda (kısa ve uzun programda) kullanılarak otoklav post-polimerizasyonuna tabi tutuldu ve 5 mm/dak hızla 3 nokta bükülme testi uygulandı. İstatistiksel analiz için iki yönlü ve tek yönlü ANOVA ve Tukey’s HSD testleri kullanıldı. Bulgular: Mikrodalga ile post-polimerizasyon, her iki akriliğin bükülme direncini anlamlı olarak arttırmıştır (p0.05). Sonuç: Otoklav ile post-polimerizasyon yöntemi, direkt yöntemle besleme yapılmış hareketli protezin bükülme direncini arttırabilecek bir uygulama olarak önerilebilir.Purpose: To compare the effect of autoclave and microwave post-polymerization treatments on flexural strength of hard reline and heat-polymerized acrylic resins. Material and Methods: Hard chairside reline and heat-polymerized acrylic resin specimens (64x10x3.3 mm) were fabricated. 80 specimens with 4 subgroups for each acrylic (n=20) received post-polymerization treatment by microwave irradiation and two autoclave post-polymerization mo- dalities (short and long). Specimens were subjected to flexural strength testing using 3-point bending with a crosshead speed of 5 mm/min. Two-way, one-way ANOVA and Tukey’s HSD tests were used for statistical analysis of data. Results: The microwave post-polymerization significantly increased the strength of heat polymerized acrylic resin and hard chairside reline resin specimens where its effect was significantly higher than the autoclave and control groups (p<0.01). Both autoclave groups presented higher strength values than the control group (p<0.01). For both materials, the difference between the mean flexural strength values of short and long autoclave application was statistically insignificant (p>0.05). Conclusion: Using autoclave, may be considered as a viable post-polymerization treatment alterna- tive in order to increase the flexural strength of relined dentures

Effect of screw access channel filling materials on uniaxial retentive force of cement-retained implant restorations

Background: This study aimed to investigate the effect of various abutment screw access channel filling materials on the uniaxial retention of castings cemented onto the abutment using temporary cement. Methods: Ten straight, regular platform Esthetic Abutments were used. Fifty castings were divided into five groups and the abutment screw access channels were filled with composite resin (Filtek Z 250), light-cured temporary filling (Clip), temporary filling (Coltosol), polyvinyl siloxane impression material (Elite H-D), or polytetrafluoroethylene (PTFE) tape. Castings were cemented and thermal cycled. A uniaxial tensile force with a cross-head speed of 5 mm/min, was applied to the castings until cement failure occurred. One-way analysis of variance was used to perform intergroup comparisons of the mean uniaxial retentive force (URF) values and Tukey's HSD test was used to determine the group causing the difference. Results: There were statistically significant differences between the mean URF values for the groups (p < 0.01). The mean URF value for the composite resin group was statistically higher than those for the other filling material groups respectively (p < 0.05). Conclusions: The retention of castings cemented to straight implant abutments using non-eugenol temporary cement may be influenced by the screw access channel filling material