The purpose of this study is to evaluate and compare the clinical performance of dental restorative materials in Class II cavities of primary molar teeth

Restorations will be placed on four primary molar teeth with proximal caries, in a split mouth design. 100 patients will be included in the study. The teeth will be randomized into four groups according to the restorative materials.

Group 1: Adhesive agent+ Compomer (Dyract AP, Dentsply DeTrey, Konstanz,Germany) Group 2: Primer + Resin modified glass ionomer (Vitremer, 3M ESPE, U.S.) Group 3: Adhesive agent + Giomer (Beautifil II, (Shofu Dental, Tokyo, Japan) Group 4: Amalgam (Permite amalgam, SDI Limited, Bayswater, Australia) The restorations will be evaluated at baseline, 3., 6., 12. months for the first year, and at every 6 months for 5 years. The modified US Public Health Service criteria (secondary caries, marginal integrity, marginal discoloration and retention) will be used for clinical evaluation of restorations. The data will be analysed statistically using Wilcoxon test, chi square test and the Kaplan-Meier survival method will be used to estimate survival percentages.

Inclusion Criteria:

• Patients and parent of the patients who accept to participate and sign the informed consent
• Patients who have at least four first and/or second primary molars with proximal caries that require class II restorations
• Teeth that have healthy lamina dura and periodontal ligament
• Teeth that have caries lesions extending no more than the outher half of dentin radiographically

Exclusion Criteria:

• Patients and parent of the patients who don't accept to participate and sign the informed consent
• Teeth that are previously restored
• Patients who are uncooperative
• Teeth that doesn't have proximal or occlusal contacts with adjacent healthy teeth
• Patients who have bruxism, skeletal or dental malocclusion
• Teeth that have developmental defects or anomalies