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VOL. 6, ISSUE 12 (2020)
Scanning electron microscopic study of tensile bond strength with acidulated phosphate fluoride applied before and after acid etching: in vitro
Authors
G Viswanathan
Abstract
Introduction: In the field of orthodontics for more than 60 years is the acid etch technique introduced by Buonocore in 1955 that has been used in the direct bonding of orthodontic brackets many studies have proven that topical fluoride is effective in increasing resistance to dental caries or enamel decalcification. These include pretreatment with topical fluoride before etching incorporation of fluoride in the etching solution, and topical application of fluoride in the etched surface before bonding. The mechanism by which fluoride reduces decalcification and caries has also been shown to increase the resistance of enamel to acids This study aims to evaluate the bond strength with acidulated phosphate fluoride before and after acid etching. Detect the changes with the scanning electron microscope on the enamel surface after debonding with the fluoride application before and after acid etching.
Materials and Methods: Sixty human premolar teeth were extracted were washed and immersed in a closed plastic box with physiologic saline solution to keep them free from fungal and bacterial contamination for period of 3 months. The teeth were randomly divided into three groups of 20teeth each for testing tensile strength The specimens were mounted on an acrylic block of dimension (4x2x1cm) to make it compatible to the jigs of the Hounsfield universal testing machine The specimens of Group 1 (Control Group) the etchant solution was applied on the buccal surface of each crown for 15 seconds then rinsed with an abundant spray of water for 10 seconds and dried with an air spray The etched surface became chalky white in appearance.
In the group 2 the teeth were immersed in APF gel (Vishal Pharma Ahmedabad) for 4 minutes. The treated teeth were removed from the APF gel and left untouched for 30 minutes. Subsequently the gel was washed off with a 1 minute water spray. The enamel of each tooth was etched for 15 seconds with acid solution for bonding.
In the third group the etchant was applied for 15 seconds, rinsed and dried as in the control group. However the crowns of the teeth were immersed in APF gel for 4 minutes after etching. The buccal surfaces of the teeth were abundantly washed with a water spray for 10 seconds then dried again etched enamel and bracket base were coated with a sealant and the composite resins (3M Unitek Co, USA) immediately applied to the bracket base. The brackets were accurately pressed to the demarcated etched buccal enamel with a placement scalar. To test the tensile strength the acrylic blocks with Hounsfield Universal Testing Machine specimen tooth was mounted the force at which the bond failed was recorded as breaking load and the bond strength The debonded interface in each group were observed with an SEM. The samples were coated all over to a thickness of about 20pm with gold as the conducting material.
Results: The mean tensile strength of control group (Group 1) 7.15 MPa
Group II (APF application before acid etching 7.015 MPa and
Group III. APF application after acid etching 5.26 MPa
Conclusion: The results showed that there is no statistically significant difference in bond strength with the APF application before acid etching but there is significant decrease in bond strength with APF application after acid etching compared to the control group.
In the SEM APF gel produced surface coating appeared to consisting of densely packed small spherical globular structure present in before and after acid etching.
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Pages:101-105
How to cite this article:
G Viswanathan "Scanning electron microscopic study of tensile bond strength with acidulated phosphate fluoride applied before and after acid etching: <em>in vitro</em>". International Journal of Medical and Health Research, Vol 6, Issue 12, 2020, Pages 101-105
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