BackgroundThe objective of this study was to verify the hypothesis that enamel deproteinization with papain gel at concentrations of 2%, 4%, 6%, 8%, and 10% increases shear bond strength as concentration increases.MethodsA total of 180 bovine mandibular permanent incisors were used, divided into six groups (n = 30), and denominated as follows: group 1 is the control group (CG) in which brackets are bonded with resin-modified glass ionomer cement (RMGIC) according to the manufacturer's recommendations and groups 2, 3, 4, 5, and 6 have brackets bonded with RMGIC after enamel deproteinization with papain gel at concentrations of 2%, 4%, 6%, 8%, and 10%, respectively. After bonding, teeth were immersed in artificial saliva and kept at a temperature of 37°C for 24 h. Mechanical tests were then performed in a universal mechanical test machine EMIC DL 5000 (Sao Jose dos Pinhais, Brazil). Values obtained were submitted to analysis of variance and then to Tukey's test (p < 0.05).ResultsThe results demonstrated that groups 5 and 6 showed the highest shear bond strength, differing statistically from the other groups (p < 0.05). CG with no papain gel used showed the lowest value and in turn showed no differences for groups 2, 3, and 4. As regards adhesive remnant index, CG showed statistical differences from the others. Groups 2, 3, 4, 5, and 6, in which papain gel was used, presented no statistical differences among them (p > 0.05).ConclusionsIt was concluded that enamel deproteinization with 8% and 10% papain gel increases shear bond strength of orthodontic brackets bonded with RMGIC.

OBJECTIVE: To investigate the effects of different sterilization/disinfection methods on the mechanical properties of orthodontic elastomeric chains. METHODS: Segments of elastomeric chains with 5 links each were sent for sterilization by cobalt 60 (Co60) (20 KGy) gamma ray technology. After the procedure, the elastomeric chains were contaminated with clinical samples of Streptococcus mutans. Subsequently, the elastomeric chains were submitted to sterilization/disinfection tests carried out by means of different methods, forming six study groups, as follows: Group 1 (control - without contamination), Group 2 (70°GL alcohol), Group 3 (autoclave), Group 4 (ultraviolet), Group 5 (peracetic acid) and Group 6 (glutaraldehyde). After sterilization/disinfection, the effectiveness of these methods, by Colony forming units per mL (CFU/mL), and the mechanical properties of the material were assessed. Student's t-test was used to assess the number of CFUs while ANOVA and Tukey's test were used to assess elastic strength. RESULTS: Ultraviolet treatment was not completely effective for sterilization. No loss of mechanical properties occurred with the use of the different sterilization methods (p > 0.05). CONCLUSION: Biological control of elastomeric chains does not affect their mechanical properties.

Introduction: Elastomeric chains are relevant in orthodontic mechanics due to the form memory property; however, elastomers present high force reduction in some circumstances. The objective was to evaluate the effect of hot beverages on tensile strength degradation of orthodontic elastomeric chains. Material and Methods: Four groups were tested according to different immersion liquids: artificial saliva (group 1), hot water (group 2), green tea (group 3), and coffee (group 4). The elastomeric chains of groups 2, 3, and 4 were immersed in the respective liquids, with temperature of 70 ± 1°C twice daily for 30 seconds for a period of 7, 14, or 21 days. All samples were kept in artificial saliva and stored in an incubator at controlled temperature of 37 ± 1°C. The elastomeric chains were then examined in the testing machine (AME-2kN; Filizola, São Paulo, Brazil) to measure the tensile strength degradation. Results: It was observed through intragroup comparisons that the control showed a progressive reduction of tensile strength in a statistically significant manner throughout the study period. In turn, the hot water, green tea, and coffee samples showed a statistically significant reduction from 7 to 14 days. From 14 to 21 days, the tension remained stable. When the test groups were compared with the control, it was observed that all groups presented tension reduction in a statistically significant manner at all periods, except for the coffee group at 21 days ( P < .001). Conclusions: Experimental immersion in hot water, green tea, and coffee at 70 ± 1°C contributed in a statistically significant manner to the strength degradation of orthodontic elastomeric chains in the period of 7 and 14 days.

ObjectivesThis study aimed to evaluate the capacity of 2% chlorhexidine gel associated with 8% papain gel in comparison with 5.25% sodium hypochlorite in bovine pulp tissue dissolution.Materials and MethodsNinety bovine pulps of standardized sizes were used and fragmented into 5-mm sizes. The fragments were removed from the root middle third region. They were divided into 6 experimental groups (n = 15), 1) 8% papain; 2) 2% chlorhexidine; 3) 2% chlorhexidine associated with 8% papain; 4) 0.9% saline solution; 5) 2.5% sodium hypochlorite; and 6) 5.25% sodium hypochlorite. The pulp fragments were weighed and put into immobile test tubes for dissolution for time intervals of 30, 60, 90, and 120 min.ResultsThe 5.25% sodium hypochlorite had greater dissolution potential than the pure papain, and when associated with chlorhexidine, both promoted greater dissolution than did the saline solution and 2% chlorhexidine groups (p < 0.05). The 2.5% sodium hypochlorite promoted dissolution to a lesser extent than the groups with papain within a period of 30 min (p < 0.05), but, was comparable to the saline solution and chlorhexidine. After 120 min, the 2.5% and 5.25% sodium hypochlorite promoted dissolution of 100% of the pulp fragments, and papain, 61%, while chlorhexidine associated with papain and chlorhexidine alone dissolved only 55% and 3%, respectively.ConclusionsThe 8% papain in gel, both alone and in association with chlorhexidine, was able to dissolve bovine pulp tissue, but to a lesser extent than did 5.25% sodium hypochlorite.

Introduction: Effects of cigars in the performance of dental restorative materials have been largely investigated; however, no information about the role of smoking cigars in strength degradation of orthodontic elastics has been revealed. Aim of the study: evaluate the effect of smoke derived from cigarette combustion on the strength degradation of orthodontic chain elastics. Materials and methods: Four distinct elastics from two different manufacturers were evaluated: Maximum Power Chain Pearl (OTP) (OrthoTechnology); Maximum Power Chain Pearl Tone Blue (OTPB) (OrthoTechnology); Orthodontic Elastic Chain Gray (MG) (Morelli); Orthodontic Elastic Chain Crystal (MC) (Morelli). Elastic segments were distended and exposed for eight minutes, twice a day with interval of 12 hours to cigarette combustion smoke. Elastic tension was evaluated at baseline, 7, 14 and 21 days. Results: the findings have shown that all elastics presented progressive tension reduction over the period evaluated. Statistically significant differences were evidenced from the baseline to 7 days and from 14 to 21 days period. The OTP and OTPB elastics presented greater initial tension when compared to the MG and MC elastics. This pattern was reproduced throughout the study periods. When test groups were compared to the control in the period of 21 days, it was observed that cigars combustion smoke reduced in a statistically significant manner the elastic strength in all groups tested. Relative comparisons between the tested samples and control in the period of 21 days indicated that smoke exposure promoted strength loss that varied from 7% (OTP) to 12% (OTPB). Conclusion: experimental exposure to cigarettes combustion smoke contributed for the strength degradation of orthodontic chain elastics in the period of 21 days.