ABSTRACT
Purpose: This in-vitro study investigated the durability of shear bond strength [SBS] of recently introduced luting agents to human dentin
Materials and Methods: One-hundred and twenty lower molars were stored in 1% Thymol solution. The occlusal surface was prepared to a flat dentin surface. The molars were divided into six groups each of 20 specimens. Translucent plastic rings were filled with the following luting agents and luted to the prepared specimens, self-adhesive compomer luting cement, hybrid glass ionomer cement in past form and conventional glass ionomer. Bonding procedures were created according to the manufacturer instructions for each luting agent. One day after luting, 20 specimens of each luting agent were stored in water bath for 24 hours. The other 20 specimens of each luting agent were stored in water bath for 3 months and thermocycled for 10000 cycles. Shear force was applied to each specimen at the junction of the plastic ring/dentin interlace using a knife-edge rod at a cross head speed of 0.5mm/min in a universal testing machine. Non parametric methods. Kruskal-Wallis and Mann-Whitney tests at p [0.05 were used for statistical analysis
Results: Medians [SBS] in MPa before and after thermalcycling are self-adhesive compomer luting cement, [CLC. 20. 413 MPa]: hybrid glass ionomer cement, [HGI, 22,14,6 MPa] and conventional glass innomer cemnt [CGI, 17.8 8.7 MPa]. There was no statistically significant difference in the median SBS of CLC and GIP before and alter storage in water and thermalcycling, however median SBS of CLC and HGI was significantly higher than median SBS of CGI before and after thermalcycling. On the other hand long term storage in water and thermalcycling significantly decreased SBS of CLC, HGI and CGI to human dentin
Clinical Implication: Hybrid glass ionomer and sell-adhesive compomer luting cements are preferred for luting indirect restorations
ABSTRACT
The aim of this study was to evaluate the effect of ultrasonic vibration sealing on two composite restorative materials [microfilled and hybrid]. Twenty healthy male individuals were selected for in vivo study of both the plaque index [PII] for anterior teeth that were restored with composite resin restoration and streptococcus count for microbiological study before and after ultrasonic vibration. Forty extracted sound molar teeth for testing the shear bond strength and forty composite resin specimen for testing the abrasion loss of weight were used for the invitro study. Two and One way ANOVA statistical tests were used in this study. The result of this study concluded that, using of ultrasonic scaler in periodontal therapy reduced the plaque index [PII] and streptococcus count. There was a highly significant differences between teeth surfaces and composite resin restoration [microfilled and hybrid] after ultrasonic cleaning. The shear bond strength between tooth surface and composite resin was reduced after using ultrasonic vibration in parallel direction. Also, using ultrasonic cleaning in [parallel or perpendicular] direction causes significant abrasion loss of weight for composite resin [microfilled and hybrid] Clinical Implication: Using ultrasonic scaling in periodontal therapy produce good periodontal but in teeth restored with composite resin it harmful effect on the bond strength and abrasion resistance so a shield should be placed on area of restoration and the time of parallel vibration of ultrasonic device
ABSTRACT
New materials and methods for processing denture bases are introduced from time to time for use in making a complete denture. The aim of this research is to study the bond strength and warpage of two new acrylic resin materials [BITEM and experimental acrylic resin] in comparison with conventional acrylic resin and soft liner
Materials and Methods: Two new acrylic resin materials were selected for this study. BITEM is the trade name for a new acrylic resin and it is the acronym for Biocompatable Intra-oral Thermo Elastic Material and experimental acrylic is a new modification type of acrylic resin which consists of the powder of heat cured acrylic resin and liquid is two bottles [A] monomer of heat cured acrylic resin and [B] plasticizer. For tensile bond strength testing, thirty specimens for each type of material were tested using a screw-driven mechanical testing system after three interval conditions 1-after processing with 48 hours. 2- After repeated soaking for [3 times] the specimens in warm water 60°C for 10 seconds. 3- After repeated soaking for [6 times] the specimens in warm water 60°C for 10 seconds]. For warpage test. 30 identical sectional casts of pure stone representing the dimensions of the edentulous ridge at posterior palatal area were constructed for each type of acrylic materials. The vertical distance between the finished plates and the original standard casts were measured after three interval conditions as in bond strength test
Results: For tensile bond strength test. Anova test revealed that significant differences between different materials [Experimental. BITEM and soft liner] after three interval conditions [after 48 hours. 3 times soaking in hot water and 6 times soaking in hot water]. L.s.d test showed that there was significant differences at [p<0.05] between immediate deflasking and repeated 6 times soaking in hot water for experimental and BITEM materials but there was no significant differences between immediate deflasking and repeated 3 times soaking while soft liner material showed, significant differences between immediate deflasking and 3 times soaking in hot water. For warpage test, a significant differences at [P<.001] between different materials [Experimental, BITEM and acrylic resin] after three interval conditions. L.s.d test showed that there was significant differences in warpage p<0.05] between immediate deflasking and 6 times repeated soaking in hot water for experimental and BITEM materials but there was no significant differences between immediate deflasking and 3 times repeated soaking. On the other hand conventional acrylic resin showed, no significant differences between immediate deflasking and repeated soaking in hot water