A comparison of the effect of application of sodium ascorbate and amla (Indian gooseberry) extract on the bond strength of brackets bonded to bleached human enamel: An In vitro study.

INTRODUCTION: Whitening of teeth is a popular choice among dental clinicians and patients. However, the changes in enamel structure and composition induced by the bleaching agents cause a decrease in the shear bond strength of brackets leading to premature bracket debonding. Among several methods to overcome this, the most common is delaying bonding by 2-4 weeks. This waiting period can be eliminated by applying an antioxidant (sodium ascorbate) which causes a reversal in the reduction of bond strength. AIM: This study aims to compare the efficacy of a naturally occurring antioxidant (gooseberry) and sodium ascorbate in normalizing the bond strength of enamel to prebleached levels. MATERIALS AND METHODS: Seventy-two extracted premolars were divided into 4 equal groups; 1st group - control group - unbleached teeth, bonded directly, 2nd group - bleached with 16% carbamide peroxide (8 h for 1 week), then bonded. 3rd and 4th group - similarly bleached, followed by application of 10% sodium ascorbate and gooseberry extract (3 h respectively), then bonded. Bond strength was checked using Instron Universal Testing Machine. RESULTS: The bond strength of the control group was the highest and that of the carbamide group was drastically reduced. Considerable increase in the bond strength was seen after treatment with sodium ascorbate with negligible difference between sodium ascorbate and control group (P > 0.05). CONCLUSION: Treatment with gooseberry extract did improve the bond strength but was not as effective as sodium ascorbate postbleaching.

Versatile retraction mechanics: Implant assisted en-masse retraction with a boot loop.

UNLABELLED: The purpose of this paper is to explain the versatility offered by the use of arch wires with boot loops in retraction mechanics while taking direct anchorage from mini-screws. MATERIALS AND METHODS: The materials include the mini screws placed at the appropriate location and retraction arches made of 0.019 X 0.025 SS with boot loops placed distal to the lateral incisors. Mini screw provides a stable anchorage for enmasse retraction of the anterior teeth with the help of a boot loop using sliding and/or loop mechanics. RESULTS: The arch wires with boot loops have a definite advantage over the soldered/crimpable hooks because of the versatility it offers during the process of retraction. CONCLUSION: An innovative approach combining the advantages of absolute anchorage using mini implants and a retraction arch with boot loop is presented here.

Three-dimensional finite element analysis of strength, stability, and stress distribution in orthodontic anchorage: a conical, self-drilling miniscrew implant system.

INTRODUCTION: The aims of this study were to analyze the stress distribution and displacement patterns that develop in an orthodontic miniscrew implant and its surrounding osseous structures for 2 implant materials under horizontal and torsional loading, with no ossseointegration. METHODS: A numeric approach was adopted. The finite element method was used to determine the stress and displacement of the various components at a given time after miniscrew implant application, when, due to viscoelastic relaxation effects, the only remaining stress field was from the application of the orthodontic load. RESULTS: Stress distribution was not significantly different between the 2 types of implant material. Increased stress values were located at the necks of the implants and the surrounding cortical bone. Bending of the titanium miniscrew was observed in the neck region under horizontal traction. CONCLUSIONS: The differences between the values of stress and displacement we obtained for the 2 types of miniscrew were too small to be clinically significant. Optimization of the miniscrew implant composed of the titanium alloy might be achieved by increasing the bulk (quantity) of the material in the neck region. The miniscrew implant can be immediately loaded and used for group movement of teeth.