Adhesive pH and Microtensile Bond to Non-Carious Sclerotic Cervical Dentin

Bonding to sclerotic dentin occurs frequently in dentistry but bonding to this substrate has been infrequently examined. Objectives: To measure the microtensile bond strengths to sclerotic dentin on Class V Non carious Cervical Lesions (NCCL) with a commercially available adhesive at 4 levels of pH.  Methods: 40 teeth with Class V NCCLs were obtained and divided into 4 groups. The sclerotic lesion was sectioned to provide a flat bonding surface.  The control group was prepared by acid etching the sclerotic lesion with phosphoric acid (DMG Etching Gel) with a pH of 0.3 for 20 seconds followed by the application of Adper Prompt L-Pop. The second group was prepared by applying the same adhesive with pH of 0.7 following the manufacturer's instructions to the sclerotic dentin.  The 3^rd group was formed by adding .1M NaOH drop wise to the adhesive to obtain a pH of 1.2. To the fourth group, 0.5M NaOH was added to the adhesive to increase the pH value of 1.8. Images were made with SEM to analyze the etch patterns for each group at each pH.  Composite (Dentsply Caulk EsthetX) was applied to every lesion and light cured (DentLight Fusion Curing Light, 800 mW/cm²) for 10 seconds. Specimens were vertically sectioned into 1mm by 1mm “sticks” with an Isomet sectioning machine.  The sticks were placed into a special fixture mounted on an Instron and loaded in tension until interface failure at a 1mm/min crosshead speed.  Data were analyzed with ANOVA and Tukey post-hoc test (p=.06). Results: (Mean±SD).

pH	0.3 (Acid Etch)	0.7	1.2	1.8
Bond Strength	30.1±11	20.7±13	14.2±6	11.8±6

Conclusions: Significantly higher bond strengths were obtained with the 0.3 pH group on sclerotic dentin than all other groups (p<.05).  Cervical lesions may require lower pH adhesives or an etch preceding the bonding for best results.