Microleakage of Surface Sealants in Class V Restorations After Thermocycling

Abstract
Class V preparations were restored with Embrace WetBond Class V and Embrace WetBond Seal-n-Shine, using no bonding agents, and these were compared to a leading group of materials using a self-etching primer bonding agent, composite, and a surface polish/sealant.

After 1500 cycles of thermal cycling, Embrace Class V and Embrace Seal-n-Shine provided superior protection against microleakage compared to the group using self-etching bonding agents, composite, and a surface polish/sealant.

Embrace Class V and Embrace Seal-n-Shine, with fewer steps and fewer materials, offers greater protection against microleakage to the tooth and restorative surfaces, and consequently, greater protection against secondary decay.

Objective
To determine leakage of Class V restorations restored with the currently used regimen of dental materials compared to a new protocol using Embrace Class V and Embrace Seal-n-Shine. The control group was restored with a self-etching primer, bonding resin, composite restorative material, and a recently introduced surface polish/sealant material. The test group used the acid etch technique on enamel only, Embrace Class V restorative without the use of a bonding agent, and Embrace Seal-n-Shine.

Materials and Methods
Recently extracted human molars that were intact and had no carious lesions or cracks were selected for this experiment. Class V preparations were made using a high-speed bur with the occlusal margins in enamel and the cervical margins in dentin/cementum. Five teeth (n=5) for each treatment/material group were prepared and each received two Class V preparations (buccal and lingual), resulting in ten restorations suitable for evaluation. All curing was performed with a Spectrum 800 (Dentsply/Caulk, Milford, DE) with an output of 650 mW/cm².

Group A
A “leading” self-etching primer was applied to the preparation and left in place for 20 seconds. After air-thinning, the bonding resin supplied with the primer was applied, air dispersed and light cured. A well-known resin composite was used to restore the preparation and light cured for 20 seconds. The restorations were finished with paper discs and Jiffy polishing wheels and cups (Ultradent Products Inc., South Jordan, UT). After finishing, the restorations were etched with 38% phosphoric acid etch gel (Etch-Rite, Pulpdent Corporation, Watertown, MA) for 15 seconds. The surface was rinsed and dried. A recently introduced polishing and sealing material was applied to the surface with a microbrush, air-thinned and light cured for 20 seconds.

Group B
The cavity preparations were etched with a 38% phosphoric acid gel (Etch-Rite) for 15 seconds. The acid etch gel was rinsed with water, and the preparation was lightly air-dried, leaving the surface slightly moist. Embrace WetBond Class V restorative resin (Pulpdent Corporation) was used to restore the preparation. No bonding agents were used. The Embrace Class V resin was light cured for 20 seconds.

After finishing, the restorations were etched with 38% phosphoric acid etch gel (Etch-Rite) for 15 seconds. The acid was rinsed and lightly air dried leaving the surface slightly moist. Embrace WetBond Seal-n-Shine was applied to the surface with a microbrush, air-thinned, and light cured for 20 seconds.

Test Procedure
Upon completion of the restorations, Block-out resin (Ultradent Products, Inc.) was applied to the entire tooth, leaving ± 1.5 mm of tooth structure uncovered around the preparation.

All samples were then subjected to thermal cycling in water at temperatures between 5^O and 55^O C. Dwell time was 30 seconds, and transportation time between the baths was 15 seconds. Fifteen hundred (1500) cycles were performed.

After thermal cycling, the samples were immersed in 2% silver nitrate solution for two hours, rinsed thoroughly, and embedded in acrylic resin. The teeth were sectioned in a Buehler diamond saw. After the sections were exposed to ambient light, allowing the silver nitrate to oxidize, at least six cross-sections could be interpreted in a stereo light microscope.

Forty sections for each group were evaluated at the cervical margin, and forty-one sections were evaluated for each group at the enamel margin.

Data Collection and Analysis
Scores for leakage were assigned under a stereo microscope. The sections were graded as follows:

On Enamel
0 = No leakage
1 = Leakage into enamel only
2 = Leakage along enamel into dentin
3 = Leakage reaching the floor of the preparation
4 = Leakage on the floor of the restoration and extending toward the pulp

On Dentin
0 = No leakage
1 = Leakage less than 1.5 mm
2 = Leakage midway along wall of preparation
3 = Leakage reaching floor of the restoration
4 = Leakage on the floor of the restoration extending to the pulp

After the data was tabulated it was subjected to an analysis of variance (ANOVA) at a p < 0.05 (95% confidence level).

Results

Group	On Enamel	On Dentin
Group A	Mean 0.77 ± 1.11	Mean 0.65 ± 0.86
Group B	Mean 0.24 ± 0.58	Mean 0.82 ± 0.67

The ANOVA resulted in the following conclusions. In enamel, Group B had significantly less leakage than Group A. In dentin, Group A and Group B were statistically the same.

Conclusions
Embrace WetBond Class V, when sealed with Embrace WetBond Seal-n-Shine, without the use of bonding agents, provides a superior enamel seal compared to a “leading” self-etching bonding agent, composite, and polishing/sealant system. Class V and Seal-n-Shine, without bonding agents, provides the same sealing and protection to the cervical margin as the multi-step bonding system.

Embrace Class V and Seal-n-Shine offer superior marginal sealing, with fewer steps and fewer materials, than other currently available “leading” materials.