Effect of thermal recycling of metal brackets on shear and tensile bond strength.

AIM: The study was undertaken to measure the changes within the mesh pad associated with reconditioning process, measure the bond strength of new and reconditioned orthodontic brackets and correlate the changes in mesh strand diameter with changes in bond strength. MATERIAL AND METHODS: 120 clinically normal premolar teeth extracted for orthodontic reasons, were divided equally for bonding with new and recycled brackets using a no-mix type of adhesive. The mesh strand diameters of new and reconditioned brackets were evaluated with a binocular light microscope. Recycling of brackets was done using Esmadent® bracket and band reconditioner. RESULTS: The mesh strand diameter, tensile and shear bond strength of new and reconditioned brackets were evaluated statistically and the latter was found to show a significant reduction (p< 0.0001). However, the bond strength values of the reconditioned brackets were found to be well above the clinically required minimum. CONCLUSION: Reduction in mesh strand diameter, as a result of reconditioning process, does not correlate with the change in bond strength between initial and recycled bondings. CLINICAL SIGNIFICANCE: The bond strength of reconditioned brackets is adequate enough to resist the magnitude of forces generated in the mouth, throughout the duration of orthodontic treatment for successful treatment results.

High risk of HIV in non-brothel based female sex workers in India.

BACKGROUND: Heterosexual contact is the most common mode of HIV transmission in India that is largely linked to sex work. We assessed the non-use of condoms in sex work and with regular sex partners by female sex workers (FSWs), and identified its associations that could assist in planning HIV prevention programmes. METHODS: Detailed documentation of various aspects of sex work, and sexual behaviour with regular sex partners, was done through confidential interviews for 6,648 FSWs in 13 districts in the Indian state of Andhra Pradesh. Multivariate analysis was done to understand condom non-use with clients. RESULTS: 5,010 (75.4%), 1,499 (22.5%), and 139 (2.1%) FSWs were street-, home-, and brothel-based, respectively. Of the total 6,648 FSWs, 6,165 (92.7%) had penetrative vaginal/anal sex with at least one client in the last 15 days, and of these 2,907 (47.2%; 95% CI 41.2-53.2%) reported non-use of condom with at least one of her last three clients. Lack of knowledge that HIV could be prevented (odds ratio 5.01; 95% CI 4.38-5.73), no access to free condoms (odds ratio 3.45; 95% CI 2.99-3.98), being street-based as compared with brothel-based (odds ratio 3.36; 95% CI 1.87-6.04), and no participation in FSW support groups (odds ratio 2.02; 95% CI 1.50-2.70) were the most significant predictors of condom non-use with clients. Other associations included lower social support, lower income, age >24 years, illiteracy, and living in medium-size urban or rural areas. Of the 2582 who had penetrative sex with regular sex partner within the last 7 days, 2428 (94%; 95% CI 92.1-95.9%) had not used condom at last sex, and 1032 (41.8%) had neither used condom consistently with clients nor with regular sex partner. CONCLUSION: About half the FSWs do not use condom consistently with their clients in this Indian state putting them at high risk of HIV infection. Non-brothel-based FSWs, who form the majority of sex workers in India, were at a significantly higher risk of HIV infection as compared with brothel-based FSWs. With their high vulnerability, the success of expansion of HIV prevention efforts will depend on achieving and sustaining an environment that enables HIV prevention with the non-brothel based FSWs.

A comparative evaluation of dimensional stability of three types of interocclusal recording materials-an in-vitro multi-centre study.

BACKGROUND: The introduction of different interocclusal recording materials has put clinicians in dilemma that which material should be used in routine clinical practice for precise recording and transferring of accurate existing occlusal records for articulation of patient's diagnostic or working casts in the fabrication of good satisfactory prosthesis. In the era of developing world of dentistry the different materials are introduced for interocclusal record with different brand names because of this; the utility of the material is confusing for successful delivery of prosthesis with lack of in vitro or in vivo studies which will predict the property of the material with utility recommendations. PURPOSE OF THE STUDY: The aim of this multicenter research is to evaluate the time dependent linear dimensional stability of three types of interocclusal recording materials; which gives very clear idea to clinicians in regard to its usage in routine practice and recommendations for usage of the different materials. Also to find out ideal time for articulation of three types of interocclusal recording materials with accuracy. MATERIALS AND METHOD: Commercially available and ADA approved Polyether bite registration paste (Ramitec), Poly vinyl siloxane bite registration paste (Jetbite) and Zinc oxide eugenol (ZOE) bite registration paste (Super bite) were used in the study.A stainless steel die was made according to modified American dental Associations (ADA) specification no. 19. Each one of the tested materials were manipulated according to manufacturers' instructions. The materials separated from die, 3-mins after their respective setting time, resulted in disks of standard diameter. Two parallel lines and three perpendicular lines reproduced on the surface. The distance between two parallel lines was measured at different time intervals i.e. 1 hour, 24, 48 and 72 hours by using travelling microscope (magnus) and compared with standard die measurements made according to ADA specification no.19 to find out the dimensional stability of these interocclusal recording materials. Total 120 samples were made for observation and results were subjected to statistical analysis. Statistical analysis was performed using analysis of variance (ANOVA) and then Tukey's Honestly Significant Difference (HSD) test for comparison among groups at the 0.05 level of significance. After statistical analysis of the data, results were obtained and analyzed for interpretation. RESULTS: The results shows significant difference between the dimensional stability of all three material at different intervals with p-value <0.05. Comparatively the polyether bite registration material showed less distortion with good dimensional stability compared to Poly vinyl siloxane bite (Jetbite), Zinc oxide eugenol(ZOE) bite (Super bite) at 1 hour, 24, 48, and 72 hours. CONCLUSION: The dimensional stability decreased with increase in time and is influenced by both material factor and time factor. Polyether was found to be more dimensionally stable interocclusal recording material, which was followed by Silicone and Zinc oxide eugenol (ZOE). The dimensional stability of Polyether was good. Zinc oxide eugenol is dimensionally more unstable when compared with polyether and polyvinyl siloxane. We recommend that the polyether interocclusal records must be articulated within 48 hours and Polyvinylsiloxane interocclusal records must be articulated within 24 hours and the ZOE should be articulated within 1 hour to get a correct restoration to have very minimum distortion and maximum satisfaction without failure of prosthesis.