In Vitro Comparative Evaluation of Newly Produced Desensitizer, Chlorhexidine and Gluma on Bond Strength and Bond Longevity of Composite to Dentin

STATEMENT OF THE PROBLEM

 Etching process on dentin can activate matrix metalloproteinase (MMP) which hydrolyze organic matrix of demineralized dentin. Gluma and chlorhexidine could inhibit the activation of MMP.

PURPOSE

 The aim of the study was to evaluate the effect of a new desensitizing material consisting of Gluma and chlorhexidine together on the shear bond strength and bond durability of composite restorations.

MATERIALS AND METHOD

One hundred and twenty caries-free extracted premolars were sectioned horizontally from one third of the coronal crown to expose flat dentin surface and randomly divided into 4 groups. In the control group, no surface treatment was used. In the first group chlorhexidine (CHX) 2%, in the second group, new material (NM) and in third group Gluma desensitizer (GD) was applied after etching and before bonding(total-etch bonding system). After the bonding process, the composite was placed on the surface of the samples using a cylindrical mold. Then, the shear bond strengths of half of the specimens were measured after 24 hours and the other half after 6 months of storage in distilled water and thermocycling. The failure types of specimens were evaluated with a stereomicroscope. Data were analyzed using One-way Anova and Tukey's Post Hoc tests in SPSS software.

RESULTS

  After 6 months, the bond strength decreased in all groups and differences were statistically significant (p= 0.002).The highest shear bond strength was observed after 6 months in the NM group and the GD group with no statistically significant difference. The 24-hour bond strengths were not significant between groups. Mix failure had the highest rate in all groups.

CONCLUSION

 It can be concluded that the effect of combination of chlorhexidine and Gluma on maintaining the integrity and strength of bond over time is similar to Gluma compound alone and they have better effect than chlorhexidine.

Effect of different decontamination procedures from a saliva-contaminated cured bonding system (Single Bond)

BACKGROUND

A few studies have investigated the effect of saliva contamination of cured or uncured adhesive systems. The aim of this study was to compare the effect of different decontamination methods on the shear bond strength of composite to enamel and dentin using an adhesive contaminated after light activation.

MATERIALS AND METHODS

In this in vitro experimental study, 80 extracted sound human teeth, 40 premolars and 40 central incisors were selected for dentin and enamel specimen preparation. Within each of the two test groups, the teeth were randomly subdivided into five groups. The materials used consisted of single bond (3M) and Z250 (3M). Except group 1 (Control), in Groups 2-5, cured adhesive was contaminated with saliva (20 s). Decontaminating procedures were rinsing, blot-drying, rebonding (Group 2), rinsing, air-drying, rebonding (Group 3), etching, rinsing, blot-drying, rebonding (Group 4) and etching, rinsing, blot-drying (Group 5). Then, composite resin was inserted on the treated surfaces and cured. The results were subjected to one-way ANOVA and Tukey honestly significant difference (HSD) tests.

RESULTS

Group 5 (etching, rinsing, blot drying) resulted in significantly lower bond strength to both enamel and dentin surfaces in comparison with the other groups (P < 0.05).

CONCLUSION

When the adhesive was re-applied, all decontamination methods in this study seemed sufficient to decrease the adverse effect of saliva.