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J Dent Sci 2010;5(1):8−13

O R IGINAL ART ICL E

Effect of 1% chlorhexidine gel on the bonding strength to dentin
Mehmet Dalli,1* Ertuğrul Ercan,2 Yahya Orçun Zorba,3 Bayram İnce,1 Cafer Şahbaz,1 Emrullah Bahşi,1 Hakan Çolak2 ˙
1 2

Department of Operative Dentistry, Dental School, Dicle University, Diyarbakir, Turkey Department of Operative Dentistry, Dental School, Kirikkale University,Kirikkale, Turkey 3 Department of Operative Dentistry, Dental School, Erciyes University, Kayseri, Turkey

Received: Oct 13, 2009 Accepted: Jan 10, 2010 KEY WORDS:
adhesion; bond strength; cavity disinfection; chlorhexidine gel; posterior composite resin

Background/purpose: The purpose of this in vitro study was to evaluate the effect of 1% chlorhexidine (CHX) gel on dentin bond strengthsof posterior composite resin applied with two different adhesive systems. Material and methods: In total, 75 extracted, caries-free human molars were used. The occlusal surface of each tooth was ground to create a flat dentin surface. Then, each tooth was mounted in acrylic. The dentin specimens were randomly assigned to five groups of 15 specimens each. In Group 1, Prime & Bond NT (PBNT) wasapplied; in Group 2, a 1% CHX gel + etching for 15 s + PBNT were applied; in Group 3, etching + 1% CHX gel + PBNT were applied; in Group 4, Clearfil S3 Bond was applied; and in Group 5, 1% CHX gel + Clearfil S3 Bond were applied. A dentine bonding system was applied to dentin surfaces, and composite cylinders were built up using a special device and then light-polymerized. Specimens were mounted andsheared using an Instron universal testing machine at a cross-head speed of 0.5 mm/min. Results: The results were recorded in megapascals. The sheared specimens were examined under a light microscope, and the type of failure (adhesive, cohesive or mixed) was recorded. Data were compared by one-way analysis of variance and Tukey’s honestly significant difference tests. Means were 16.4 ± 4.1 MPa inGroup 1, 16.2 ± 3.9 MPa in Group 2, 13.0 ± 4.5 MPa in Group 3, 11.9 ± 2.7 MPa in Group 4, and 11.5 ± 2.7 MPa in Group 5. The use of 1% CHX gel before acid etching was significantly higher than after etching on the shear bond strength of PBNT (P < 0.05), but did not differ significantly from PBNT alone (P > 0.05). Conclusion: Within the limitations of the present in vitro study, it was concluded that1% CHX gel application did not adversely affect the shear bond strengths of dentin-bonding agents.

Introduction
In response to increasing esthetic demands of patients, the use of composite resin materials for posterior tooth restorations is increasing.1 This increase

is due primarily to demands for improved esthetics. However, it is generally accepted that resin composites are not yet ableto guarantee excellent results when used for posterior tooth restorations. This is due to postoperative sensitivity and penetration of

*Corresponding author. Department of Operative Dentistry, Dental School, Dicle University, Diyarbakir 21230, Turkey. E-mail: mdalli@dicle.edu.tr ©2010 Association for Dental Sciences of the Republic of China

Chlorhexidine gel on the bonding strengthmicroorganisms and/or their toxic products that, in turn, can cause pulpal lesions and secondary caries.2 Bacterially contaminated cavity walls associated with caries are a potential problem in restorative dentistry.3 Bacteria can remain in the smear layer or in dentinal tubules, and can potentially multiply.4 Studies indicate that residual bacteria might proliferate from the smear layer beneathrestorations, allowing toxins to diffuse to the pulp, resulting in irritation and inflammation.3,4 It was argued that microorganisms that are present in the cavity walls cannot be removed by the use of water spray or by the effect of restorative materials containing disinfecting agents.5 Therefore, the adjunctive use of antibacterial solutions after cavity preparation may be considered a method to...