Clinical Performance of Prime&Bond Active in Self-etch or Selective-etch Mode With or Without Bioglass

The protocol to be followed in the study is as follows:

1. Obtention of a written informed consent of all participants.
2. Complete medical and dental clinical record.
3. Administration of anesthesia and absolute rubber dam isolation.
4. Cavity cleaning with a prophylactic brush and rubber cup with pumice.

5. Randomly assigning each non-carious cervical lesion to one of the four experimental groups:

   5.1. Selective enamel etching and surface roughening with bioglass 5.2. Selective enamel etching without surface roughening. 5.3. Self-etch and surface roughening with bioglass. 5.4. Self-etch without surface roughening.

6. In experimental groups which need surface roughening (group 5.1 and 5.3), sandblasting with bioactive glass will be used in enamel.

7. In experimental groups with selective enamel etch (5.1 and 5.2), 37 % orthophosphoric acid is applied for 15 seconds in enamel, followed by profuse washing with air/water spray for ten seconds and dried using air for 10 seconds without desiccating dentin.

   In groups 5.3 and 5.4 this step is omitted.

8. Application of universal adhesive Prime&Bond Active on enamel and dentin for 20 seconds. Subsequently, evaporation of the solvent is realized by applying air for 5 seconds and then light curing for 20 seconds.
9. Application of a "bulk fill" composite resin and light curing, following manufacturer's instructions.
10. Finishing and polishing of the restoration.
11. Monitoring and follow up: visits will be performed at six months, one year, two years and three years. In each evaluation, two independent clinicians who do not participate in the clinical procedures will evaluate each direct composite restoration according to USPHS criteria (Modified United States Public Health Service).

The primary objective is to evaluate the retention of the restoration. The secondary objectives are to evaluate marginal discoloration, marginal integrity and marginal caries.