Influence of dry and wet storage conditions on bond strength to gold alloy of four luting agents

Mika Furuchi, DDS, PhD,(a,b) Akiko Oshima, DDS,(a) Yoshifumi Matsumoto, DDS,(c) Michiya Ayano, DDS,(a) Tsukasa Masuno, DDS,(a) and Hideo Matsumura, DDS, PhD,(a,b)

(a)Department of Fixed Prosthodontics, Nihon University School of Dentistry, (b)Division of Advanced Dental Treatment, Dental Research Center, Nihon University School of Dentistry, and (c)Nihon University Graduate School of Dentistry, Tokyo, Japan

Purpose: The purpose of the current study was to evaluate the influence of water storage conditions on bond strength of four luting agents joined to gold alloy.
Materials and Methods: Disk specimens (10 and 8 mm in diameter) were cast from a gold alloy (Degudent U), and the surfaces were ground with abrasive paper. Two resin-modified glass ionomers (RMGIs; Fuji Lute and Ionotite), a resin adhesive (Super-Bond C&B), and a conventional glass ionomer (Ketac Cem) were selected for bonding the gold alloy. A metal priming agent (Metaltite) was used together with the Fuji Lute and Super-Bond C&B materials. The paired specimens were bonded with five systems and placed in an incubator at 37ºC under three different conditions; 1) immersed in water for 24 h, 2) immersed in water for 24 h followed by additional 7-day-immersion in water, and 3) immersed in water for 24 h followed by dry-state storage for 7 days. Shear bond strengths were then determined and statistically analyzed. Weight change of luting agents after storage was determined using disk-shaped specimens (10 mm in diameter by 2 mm in thickness).
Results: Shear bond strength varied from a minimum of 0.1 MPa to a maximum of 40.9 MPa. Bond strength of Fuji Lute and Ketac Cem deteriorated after 7 days for both dry and wet storage conditions, whereas bond strength of Super-Bond C&B without priming improved after dry-storage. Bond strength of Ionotite and Super-Bond C&B with priming remain unchanged during the three storage conditions of the current experiment. Weight change of luting agents after storage was +1.6 to +5.5% for condition #1, +2.6 to +6.0% for condition #2, and -4.5 to -0.4% for condition #3.
Conclusion: Within the limitations of this experiment, it can be concluded that the use of either Ionotite alone or Super-Bond C&B combined with Metaltite is recommended for bonding gold alloy.
(Int Chin J Dent 2008; 8: 43-47.)
Key Words: bonding, gold alloy, primer, resin-modified glass ionomer, thione.