11/17/2010 Comparing Bond Strengths of Brackets on Primary Teeth With 3 Different Primers

Resident: Hencler
Date: 11/17/2010

Article title: Comparing Bond Strengths of Brackets on Primary Teeth With 3 Different Primers

Author(s): Ozoe-Ishida, Endo, Shimooka
Journal: Pediatric Dentistry V32/NO2 MAR/APR 10
Major topic: Bonding strengths
Type of Article: Scientific

Main Purpose:
Examine the bond strengths and the mode of bracket failure in brackets bonded to primary tooth enamel using conventional primers, self-etching primers, and moisture-insensitive primers.

Overview of method of research:
78 primary teeth (30 canines, 24 first molars, 24 second molars) were collected and divided equally into 6 groups of 13 teeth. In group 1 the enamel surface was etched and a coat of conventional primer was applied to the enamel surface. In group 2 a coat of self-etching primer was applied to the enamel surface. In group 3 the enamel surface was etched and a coat of moisture-insensitive primer was applied. The adhesive systems used in groups 4, 5, and 6 were the same as those used in groups 1, 2, and 3, respectively, but before priming, each tooth in groups 4, 5, and 6 was moistened with a thin coat of water. Transbond XT was used to attach each bracket. A universal testing machine was used to test the bond strengths for each group in Newtons. The bond strengths were checked against 6MPa, which is considered to be the minimum clinically acceptable bond strength.

Findings: See tables

Key points in the article discussion:
Among the factors that govern bond strengths are types of adhesives, types of ortho brackets, type of teeth, and moisture contamination. This study found a notable drop in bond strength of the conventional adhesive system in a moisture-contaminated environment and a high incidence of bond failure at the enamel-adhesive interface. The moisture insensitive primer adhesive system is hydrophilic. The self-etching primer adhesive system can be used in either dry or wet fields. By contrast, the conventional adhesive system is hydrophobic. Failure is likely due to insufficient formation of resin tags as a result of the decreased permeation of the bonding agent into primary tooth enamel under conditions of moisture contamination. All bond strengths found in this study were less than 6 MPa. The low levels of shear bond strength in primary teeth vs. permanent teeth could be attributed to differences in the surface structure of enamel or the thickness of adhesives placed b/t the bracket base and enamel surface. The enamel surface of primary teeth is predominantly prismless vs. permanent teeth. Furthermore, the ratios of moisture and organic contents of primary teeth enamel are higher and the ratio of inorganic contents was lower than those of permanent teeth. These characteristics of primary tooth enamel account for poorly developed etching patterns and cause lower bond strength.

Summary of conclusions:
1) The conventional primer adhesive system does not offer adequate bond strength of brackets bonded to primary tooth enamel under wet conditions. 2) The self-etching primer adhesive system and moisture insensitive primer adhesive system have clinically acceptable bond strengths of brackets bonded to primary tooth enamel in either dry or wet conditions. 3) These adhesive systems under specific conditions enable practitioners to use a primary tooth in the sectional bracket appliance as an anchor tooth, thus helping improve the outcome of early treatment for malocclusion.

Assessment of article:
Okay article, a little boring and nothing groundbreaking. When bonding brackets using any adhesive system, attention to detail and moisture control are very important and will ensure less frequent bracket failure on primary or permanent teeth.