[Comparison of the microleakage and shear bond strength of four current one component dentin bonding systems]

ABSTRACT

The success of tooth-colored restorations depends on bonding them to hard tooth tissue that will retain the restoration to the cavity preparation and prevent microleakage. Different adhesive systems have been introduced that provide bonding between tooth-colored filling materials and tooth structure [dentin] that will withstand the contraction forces generated by polymerization shrinkage while maintaining a marginal seal during functioning of the restored tooth. The purpose of this investigation was to study the microleakage of class V resin restorations and the shear bond strength of composite resin to dentin using four different types of current bond adhesive systems. This experimental study has been done on 96 intact human premolar teeth extracted for orthodontic purposes within a 3-month period. The teeth were randomly divided into two parts as A and B. In part A, Standardized classic class V cavity dimensions of 3.0 mm [occlusal-gingival], 2,0 mm [mesial-distal], and 2.0 mm [depth] prepared in buccal and lingual surfaces of teeth at the cemento-enamel junction with the cervical margin in dentin or cementum and the occlusal margin in enamel. Enamel Cavosurface margin of cavities were beveled. The cavities were etched with 36% phosphoric acid for 15 second then were rinsed. The cavities were restored with a composite resin [Z100 3M ESPE] using four different dentin adhesive systems [Single Bond [3M-ESPE], Excite [vivadent], One-Step [Bisco], Prime and Bond NT [Dentsply-Detry]], The specimens' thermocycled for 3000 cycles [5-55°C] and were then immersed in a 10% solution of methylene blue dye for 72 hours. After rinsing, the restorations were sectioned buccolingualy and the microleakages were scored by an optical stereomicroscope with x40 magnification. In part B, the teeth mounted in a 2.5 cm diameter acrylic cylinder mold and buccal surfaces of teeth were ground to expose dentin. After etching and rinsing, the four adhesive systems mentioned before were applied to dentin surface with the wet bonding technique. A cylinder of Z100 dental composite with a 3 mm diameter and 2 mm height was placed on the adhesive covered dentin surface of all groups and light-cured. The specimens were kept in distilled water at room temperature for one week and then thermocycled for 3000 times [5-55oc].Shear bond strength of specimens was measured using an instron universal mechanical testing machine with the cross-head speed of 0.5 mm/minute. Data were analyzed with one way ANOVA, Kruskal-Wallis, Tukey HSD and Mann-Whitney U tests. The mean and standard deviation of shear bond strengths [Mpa] of groups were as follows One-Step19.60 +/- 1.83, Single Bond 21.44 +/- 3, Prime and Bond NT 26.51 +/- 5.02, Excite 29.78 +/- 3.85. Analysis of the results revealed that One-step had lowest and Excite had highest shear bond strength [P<0.05]. Prime and Bond system had the least and One-Step system had the most microleakage in dentin margins of restorations [P<0.05]. Single Bond and Excite bonding systems statistically had no difference in dentin marginal microleakage [P>0.05]. Different types of one bottle dentin bonding agents had different micro leakage scores and different shear bond strengths