Characteristics of light-polymerizable adhesives for bonding retentive beads to cut-back wax surfaces

Hiroyasu Koizumi, DDS, PhD,a,b Mamiko Kochi, DDS,c Kazuhiro Honda, DDS,c Michiya Ayano, DDS,a Kiyoshi Nagano, PhD,d and Hideo Matsumura, DDS, PhDa,b

aDepartment of Fixed Prosthodontics, bDivision of Advanced Dental Treatment, Dental Research Center, Nihon University School of Dentistry, cDivision of Applied Oral Sciences, Nihon University Graduate School of Dentistry, Tokyo, and dNagasaki University Hospital, Nagasaki, Japan

Purpose: The purpose of the current study was to evaluate characteristics of chemical ingredients to be used for retentive beads adhesives.
Materials and Methods: An ultraviolet light-polymerizable adhesive (Particle Bond) and 12 UV and visible light-polymerizable compositions were assessed. Undercuts created on the surface of castings were evaluated using two retentive beads adhesives; Particle Bond and Retention Beads II Adhesive. The cross section of cast specimens was observed with a confocal scanning laser microscope.
Results: In addition to the composition of Particle Bond, a dual-polymerizable material consisting of 93.5% neopentylglycol diacrylate and 6.5% light initiators polymerized satisfactorily. In evaluation of the undercut of retentive devices, the ratio of diameter of bonded area and retentive bead at an identical cross section was 0.65 for Particle Bond and 0.49 for Retention Beads II Adhesive (p<0.05).
Conclusion: Although wetting ability and polymerization performance of the Particle Bond adhesive were excellent, there was room for improvement in reproduction of undercuts. A dual-polymerizable composition was proposed for the development of a new adhesive.(Asian Pac J Dent 2011; 11: 15-18.)

Key Words: adhesive, bead, cut-back, retentive device, spherical retention