The effect of additional etching and curing mechanism of composite resin on the dentin bond strength

Comparison of the micro-tensile bond strengths of four different universal adhesives to caries-affected dentin after ER:YAG laser irradiation

The micro-tensile bond strengths (micro-TBSs) of four universal adhesive systems, applied in two different bonding techniques, to carries-affected dentin after Er:YAG laser irradiation were investigated. Twenty-four extracted human molars were divided into four groups, according to the adhesive systems used. Each group was subdivided into two subgroups, depending on the bonding method used: the etch-and-rinse procedure or self-etch procedure. The carious lesions were irradiated using an Er:YAG laser. Resin composites were used to restore the adhesive-treated dentin surfaces. After 2,500 thermal cycles, the vertical composite resin-dentin sticks obtained were subjected to micro-TBS tests. One tooth in each group was examined using scanning electron microscopy (SEM). There were statistically significant differences (p<0.001) in micro-TBS values between universal adhesives. The results of this study suggested that universal adhesives applied both with self and total etch technique can be used for adhesive restorations to caries-affected dentin after Er:YAG laser irradiation. If lasers are preferred as a caries removal method, choosing a dentin bonding agent containing MDP may be recommended in clinical practice due to the property of increasing the bonding strength.

Effect of chlorhexidine on the durability of a new universal adhesive system

Background

The effect of chlorhexidine on bond durability of universal adhesives is not clear. The aim of this study was to evaluate the effect of chlorhexidine on 6-month water storage bond strength of adhesive systems.

Material and Methods

72 freshly sound human extracted molars were selected. In each tooth both buccal and lingual sides were prepared by bur to reach superficial dentin and randomly divided into 6 groups and 12 sub-groups and bonded with Scotchbond Universal (SBU) or Scotchbond Multi-purpose (SBMP) with/without chlorhexidine (CHX) usage. Group 1: SBU, group2: SBU+CHX, group3: Etch+SBU, group4: Etch+CHX+SBU, group5: Etch+SBMP, group6: Etch+CHX+SBMP. After composite curing, water storage and thermocycling was done. Each group was divided into two subgroups. One was tested immediately, and the other was thermocycled for 5000 cycles (5-55 °C) (it was equivalent to 6 months of storage in distilled water). Shear bond strength test was done and failure modes were determined by Stereomicroscope. The data were analyzed by one-way ANOVA, Tukey post-hoc test and Paired Two test with P<0.050 as the level of significance.

Results

Shear bond strength in late SBU (Self etch) was significantly lower than late SBU [Etch and rinse (ER)], P value= 0.0001, also shear bond strength in late SBU [self-etch (SE)] was significantly lower than immediate SBU (SE), P value= 0.01. There were no significant differences between other sub-groups and conditions. The most failure mode was adhesive in all the groups.

Conclusions

Long term bonding durability of SBU(ER) was better than SBU (SE). CHX usage had prevented bond strength decrease in SBU and SBMP in long term. CHX usage did not have any effect on immediate shear bond strength of SBU and SBMP. Immediate and late shear bond strength of SBMP with/without CHX usage was similar to SBU(SE, ER). Key words:Dentin Bonding, Shear Bond Strength, chlorhexidine, 6-month storage.

The effect of double-coating and times on the immediate and 6-month dentin bonding of universal adhesives

OBJECTIVE

The purpose of this study was to evaluate the effect of double-application coats and times on microtensile bond strength (μTBS) and adhesive-dentin interfaces created by dentin adhesive systems after 6 months of storage in water.

MATERIALS AND METHODS

Two-hundred sixteen extracted non-carious human third molars were selected for the study. Single-Bond Universal (SU) and All-Bond Universal (AU), Adper Easy One (Eo) Self-Etch adhesive and Adper Single-Bond 2 (Sb) etch-and-rinse adhesive were applied to a flat dentin surface using three methods (1): dentin adhesives were applied as recommended by the manufacturers; (2): two consecutive coats of dentin adhesives were applied before photo-polymerization; and (3): a single coat of adhesive was applied but with twice the manufacturers recommended application time. Microtensile bond strength was determined either immediately or after 6 months of water storage. Data were analyzed using one-way analysis of variance and Tukey's post-hoc tests.

RESULTS

At 24 h, groups 1, 2, and 3 exhibited statistically similar results for all dentin adhesive systems. For AU-Er, group 3 showed significantly higher bond strength than all group of AU-Se after 6 months.

CONCLUSION

Universal adhesives seemed more stable against water degradation than traditional two-step etch-and-rinse and all-in-one systems within the 6-month period.

The effect of saliva decontamination procedures on dentin bond strength after universal adhesive curing

Objectives

The purpose of this study was to investigate the effectiveness of multiple decontamination procedures for salivary contamination after curing of a universal adhesive on dentin bond strength according to its etch modes.

Materials and Methods

Forty-two extracted bovine incisors were trimmed by exposing the labial dentin surfaces and embedded in cylindrical molds. A universal adhesive (All-Bond Universal, Bisco) was used. The teeth were randomly divided into groups according to etch mode and decontamination procedure. The adhesive was applied according to the manufacturer's instructions for a given etch mode. With the exception of the control groups, the cured adhesive was contaminated with saliva for 20 sec. In the self-etch group, the teeth were divided into three groups: control, decontamination with rinsing and drying, and decontamination with rinsing, drying, and adhesive. In the etch-and-rinse group, the teeth were divided into four groups: control, decontamination with rinsing and drying, decontamination with rinsing, drying, and adhesive, and decontamination with rinsing, drying, re-etching, and reapplication of adhesive. A composite resin (Filtek Z350XT, 3M ESPE) was used for filling and was cured on the treated surfaces. Shear bond strength was measured, and failure modes were evaluated. The data were subjected to one-way analysis of variation and Tukey's HSD test.

Results

The etch-and-rinse subgroup that was decontaminated by rinse, drying, re-etching, and reapplication of adhesive showed a significantly higher bond strength.

Conclusions

When salivary contamination occurs after curing of the universal adhesive, additional etching improves the bond strength to dentin.