The clinical performance of a bioactive composite and a posterior resin composite in class II restorations will be evaluated and compared. After recruiting participants with at least 2 approximal caries lesions, all restorations will be placed by a single clinician. All caries lesions will be removed before restoring. Cavities will be divided into two groups: a bioactive composite [Cention N, Ivoclar Vivadent, Schaan, Liechtenstein (CN)] and a posterior resin composite [G-ænial Posterior (GC, Tokyo, Japan) (GP)] All restorative procedures will be conducted according to manufacturers' instructions. Restorations will be scored using FDI criteria after a week (baseline) 6, 12, 24, 36 and 48 months. Descriptive statistics will be performed using chi-square tests.

Inclusion Criteria:

• age range will be 18 to 65
• patients should have at least 2 approximal caries lesions require restoration
• healthy periodontal status
• a good likelihood of recall availability

Exclusion Criteria:

• poor gingival health
• adverse medical history
• potential behavioral problems