In vitro analysis of shear bond strength of self adhesive resin and its variability on bleached enamel surface

Objective: to evaluate the shear bond strength of ninth generation self- adhesive resin as an orthodontic bracket bonding vement, second to analyze its bonding potential on the bleached enamel surface and third is to determine the appropriate time of bracket bonding after tooth bleaching is performed

Methods: sixty extracted teeth between the 13-25 age group were divided into three groups. [n=20]. Group one was a non - bleached control group. Group two was bleached and bonded on the same day. While group three was bleached two weeks prior to bracket bonding. Mechanical de bonding was performed at universal testing machine at the cross head speed 1mm/sec

Results: shear bond strength for group 1[ 7.72 +/- 2.56MPa] and group 3 [5.08 +/- 2.09MPa] was significantly higher [p<0.001] than the group 2 [2.86 +/- 0.94MPa]. The post hoc test showed the significant difference between groups [p= 0.001]

Conclusion: self adhesive resin may ease the placement of orthodotic bracket being less technique sensitive and time saving and can be employed as an orthodontic bonding agent

Comparison of local and imported osteosynthetic mandibular bone plates in terms of micro hardness in modified simulated body fluid at periodic intervals

To determine the micro hardness of novel Pakistani manufactured osteosynthetic titanium bone mini plates [MPP] and imported osteosynthetic titanium bone mini plates [MPG] in body like conditions. Descriptive study. This study was carried out at School of Chemical and Material Engineering, NUST from March to May 2013. Microvicker hardness tester was used for assessment of micro hardness of two types of plates. The hardness was checked before conditioning and after conditioning at [six different places] on interval of 1, 7, 14, 21, 28 and 40 days in modified simulated body fluid with ph 7.4 and temperature 37[degree]C. Result showed that hardness of MPG was higher than MPP and after conditioning in simulated body fluid at all time periods, hardness of both types of plates was increased. It can be concluded from this study that micro hardness of imported plates is more than local plates so recommendations should be sent to manufacturers of local industry of Pakistan to improve the hardness of local plates so that they can meet international standards

comparative analysis of bleached and sound enamel structure through scanning electron microscopy and atomic force microscopy

To analyze the effects of bleaching agent on enamel structure and to characterize the morphological and chemical changes in enamel due to bleaching. Experimental study. School of Chemical and Material Engineering [SCME], NUST Islamabad from Feb to May 2013. Ten recently extracted pre molars between the 12-22years age group were randomly assigned into two groups. Group one was a non-bleached control group with sound enamel. Group two was bleachedwith Everbrite In office tooth whitening system after specimen preparation, surface morphology was observed under SEM [scanned electron microscope] and AFM [Atomic force microscope]. Thedetrimental effects of hydrogen per-oxide on enamel were evident in bleached specimens under SEM, and AFM analysis. There were significant surface alterations found in the bleached specimens as compared to control group. However salivary buffering potentials could overcome the demineralizing effect of bleaching gel