RESUMEN
Aim: This study was performed to compare the effect of applying Pro Seal cure varnish to the enamel surface when placed before or after application on the shear bond strengths of orthodontic brackets
Methods: Sixty non carious premolars were randomly divided into three equal groups. In the first and second groups, Pro Seal, a fluoride releasing light cure varnish was applied to the enamel surface before and after the sealant provided with adhesive was placed respectively while, the third group [Control] was bonded regularly using only the sealant supplied with the adhesive. Monolok[2] no-mix bonding system was used to bond stainless steel brackets to each tooth. All teeth were embedded in self-cure acrylic and placed in steel rings and were secured in a jig attached to the base plate of a universal testing machine. A perpendicular force was applied to the bracket at a crosshead speed of 0.5mm/min. The residual adhesive on the enamel surface was evaluated after debonding with the Adhesive Remnant Index [ARI]
Results: The mean shear bond strength for Group I treated with the Pro Seal varnish before the sealant was 10.06+/- 3.11 MPa. However, for Group II, where varnish was applied after the sealant, the mean shear bond strength was 12.78 +/- 3.7 MPa, while it was 12.81 +/- 2.6 MPa for the control group. Analysis of variance test showed that the mean shear bond strengths of the three groups were not significantly different from each other. The Chi-Square test evaluating the residual adhesive on enamel surfaces showed no significant differences between all groups
Conclusions: It was thus concluded that the application of Pro Seal before or after the sealant did not reduce the mean shear bond strength of orthodontic brackets. However, further studies are recommended to compare the amount of enamel protection offered in either situation
RESUMEN
This study was performed to compare the effect of bisphosphonate [chlodronate] and a new bio-glass synthetic hydroxyappatite material on amount of orthodontic tooth movement in male dogs. The sample included 20 male strain dogs which were equally divided into two groups of 10 dogs each. Each group received local administration of each material on one side while, the contra-lateral side served as control for both groups. Banding of the second premolar and canine was performed on both sides followed by surgical extraction of the first premolar. A uniform standardized closed coil 0.01 2-inch nickel titanium closed coil spring was set in each animal's mouth between the upper second premolars and canines on both sides and ligated. The spring was stretched and initially generated lOOgm of force on each side. Each dog received 50 uL of chlodronate solution [0.9% NaCl, pH 7.4] at a concentration of 250umol/L and was injected into the sub-periosteum area adjacent to the upper left second premolar every week during the one month period of the experiment. While in the second group, bioglass material was locally injected at the second premolar area in the same way as for the first group. For both groups, the right side served as control with an injection of 50uL of 0.9% sodium chloride once per week for one month into the corresponding area. A significant retardation of second premolar movement in the bisphosphonate group was found where the percentage of inhibition of tooth movement was about 30% of the bioglass group and 80% of the control side. Histologic examination revealed that in the experimental animals a greater number of osteoblasls appeared on the alveolar bone surface at a highly significant level when compared to the control sides and inhibition of tooth movement was observed
RESUMEN
The dentoskeletal and soft tissue changes using maxillary expansion and chincap therapy in mandibular progthanic patients was investigated in this study. A sample of 20 children [14 girls and 6 boys] with a mean age of 8 years 2 months with Class III with mandiublar excess were included in the study. All patients were treated using a high pull chincap and anterior maxillary expansion plate until, a 2mm positive was achieved for a mean treatment time of 11.5 months. Cephalometric radiographs were taken before and after treatment. A significant improvement in the mesiodistal relationship of the maxilla and mandible was noted after treatment which was produced by significant downward and backward movement of the mandible where SNB angle was reduced by - 1.5° and infradentale by -1 .8mm in addition to downward migration of points B, Pogonion and Gonion and significant opening of the mandibular plane angle. The Class III incisor relationship was corrected by anterior displacement and proclination of the upper incisor along with significant decrease in the inclination of the lower incisor. The soft tissue convexity [G'SnPg'] was significantly increased due to posterior relocation of suit tissue pogonion. A significant upper lip protraction and forward movement of soft tissue A point was found in this study