Microleakage and Bond Strength of Sealant to Primary Enamel Comparing Air Abrasion and Acid Etch Technique

Meghan Sullivan Walsh August 21, 2010

Literature Review - LMC/ Providence Pediatric Dentistry

Microleakage and Bond Strength of Sealant to Primary Enamel Comparing Air Abrasion and Acid Etch Techniques

Resident: Meghan Sullivan Walsh

Program: Lutheran Medical Center - Providence

Article Title: Microleakage and Bond Strength of Sealant to Primary Enamel Comparing Air Abrasion and Acid Etch Techniques

Authors: Lisa A. Knobloch, DDS, MS; Tyra Meyer, DDS, MS; Ronald E. Kerby, DDS; William Johnston, PhD

Journal: Pediatric Dentistry

Volume Number, Month, Year, Pages ; Volume 27/Number 6, 2005, Pages 463-469

Major Topic: Comparison of bond strength and microleakage on pit and fissure sealants of primary teeth using preparations of air abrasion, acid etching and a combination of both.

Overview of Method of Research: Fourth extracted primary teeth were divided into four groups; Group 1 (control), Group 2 (acid etch group), Group 3 (KCP - air abrasion) and Group 4 (KCP plus acid etch). Each tooth was debrided, cleaned with pumise and water stored in chloramine solution. The teeth were mounted in a plastic mold and the exposed enamel surfaces were fine sanded with silison carbide paper and water to produce a flat enamel surface. The teeth were then aagin pumiced, rinsed and air dried. The enamel surfaces of each group were then either not touched (Group 1), etched rinsed and dried (Group 2), prepared with the KCP air abrasion system (Group 3) or prepared with KCP as well as etch. Clear plastic tubes were placed on the flat surface over the exposed area with adhesive tape. The tubes were there filled with sealant. The bonded specimens were stored for 7 days and then exposed to thermocycling.

Each specimen was inserted into a steel jig and a shear probe was used to test shear strength. Shear bond values were then calculated.

To test microleakage, fourty extracted primary molars were prepared exactly as above and following the thermocycling the teeth were immersed in silver nitrate dye then placed into a radiographic developer solution. The teeth were then washed and sectioned to examine leakage using digital imaging.

Findings: All ten of the control specimens failed during thermocycling. The mean shear strength of group 4 (KCP plus etch) exhibited 50% higher bong strength than group 2 (acid etch). In addition specimens bonded to enamel conditioned with etch (group 2) exhibited bond strengths that were twice those in Group 3 (KCP).The majority of bond failures in KCP were adhesive where as the acid etch and KCP plus etch exhibited both adhesive and cohesive failures. In terms of microleakage the differences of each group were not significantly different from one another. However the ranking of dye penetration as a function of occlusal conditioning from high to low is KCP>control>etch>KCPplus etch.

Key Points: For preparation of sealants in primary teeth, acid etch is the minimum requirement for retention. Air abrasion may improve the retention of sealant bond strength and microleakage. Shear bond strength was found to be higher following air abrasion and acid etching when compared to just air abrasion or acid etch alone. Microleakage may be decresed when using acid etch or a combination of acid etch and air abrasion.

Assessment of the Article: My first issue with this article was the small sample size used. Only fourty teeth were used for these experiments and were then divided into four groups. Thus only ten samples were used in each of the four categories. In addition I found confusing the preparation of the enamel surfaces with a silicon carbide paper to produce a flat enamel surface. I thought the purpose of sealants were to seal pit and fissure anatomy? Lastly the preparations, thermocycling and emersion of these samples into dyes and potions did not impress me nor do they represent the oral environment. The small sample size and little difference in the numbers and characteristics of the four groups excluding the control group makes this experiment interesting yet not convincing.