Influence of handpiece maintenance sprays on resin bonding to dentin

Toyotarou Sugawara¹, Atsushi Kameyama², Akiko Haruyama³, Takumi Oishi⁴, Nobuyuki Kukidome², Yasuaki Takase², Masatake Tsunoda²

¹Undergraduate Student, Tokyo Dental College, Chiba, Japan; ²Division of General Dentistry, Tokyo Dental College Chiba Hospital, Chiba, Japan; ³Department of Dental Materials Science, Tokyo Dental College, Chiba, Japan; ⁴Department of Dentistry and Oral Surgery, Keio University School of Medicine, Tokyo, Japan

Objective: To investigate the influence of maintenance spray on resin bonding to dentin.

Materials and methods: The crown of extracted, caries-free human molars was transversally sectioned with a model trimmer to prepare the dentin surfaces from mid-coronal sound dentin, and then uniformly abraded with #600 silicon carbide paper. The dentin surfaces were randomly divided into three groups: oil-free spray group where maintenance cleaner for air bearing handpieces was sprayed onto the dentin surface for 1 s and rinsed with water spray for 30 s; oil-containing spray group where maintenance cleaner for micro motor handpieces was sprayed onto the dentin surface for 1 s and rinsed with water spray for 30 s; and control group where the surface was rinsed with water spray for 30 s and then air-dried. These surfaces were then bonded with Clearfil SE Bond (Kuraray Medical), and resin composite (Clearfil AP-X, Kuraray Medical) build-up crowns were incrementally constructed on the bonded surfaces. After storage for 24 h in 37°C water, the bonded teeth were sectioned into hour-glass shaped slices (0.7-mm thick) perpendicular to the bonded surfaces. The specimens were then subjected to microtensile bond strength (μTBS) testing at a crosshead speed of 1.0 mm/min. Data were analyzed with one-way ANOVA and the Tukey-Kramer test.

Results: Maintenance spray-contaminated specimens (oil-free and oil-containing spray groups) showed significantly lower μTBS than control specimens (P < 0.05). However, there was no significant difference between the spray-contaminated groups (P > 0.05).

Conclusion: Maintenance spray significantly reduces the bond strength of Clearfil SE Bond to dentin.

Keywords: microtensile bond strength, lubricant, maintenance spray, contamination, dentin bonding