This study will evaluate the clinical performance of glass carbomer cement restorations in restoring proximal lesions in primary molars compared to that of resin modified glass ionomer cement and composite resin restorations. Teeth will be randomly assigned to one of the three restoration groups and the restorations will be evaluated clinically and radiographically every six months.

Glass Carbomer is a monomer free; carbomised nano-glass restorative cement developed from traditional glass ionomer cement (GIC) and contains nano-sized powder particles of hydroxyapatite and fluorapatite. These materials claim to have improved mechanical properties and better bonding to dentin, in addition to continues fluoride release.

The study is a randomized controlled clinical trial where teeth will be randomly assigned to one of the three restoration groups.

Following medical and dental history, bilateral bitewing radiographs will be taken for each patient to assess the presence of proximal lesions. Suitable teeth will then be randomly assigned to one of the restoration groups. A single operator using local anesthesia and rubber dam isolation will then prepare standardized Class II cavities and place the designated restorations according to the manufacturer's instructions.

The quality of the 3 types of restorations will be clinically evaluated at baseline and every six months for color match, marginal discoloration, anatomic form, marginal adaptation, and secondary caries using the criteria described by "Cvar and Ryge" (2005). The evaluation will be performed by 2 calibrated examiners.

Following placement of the restorations, bitewing radiographs will be taken to evaluate the restorations and will be repeated every six months for detection of recurrent caries.

Inclusion Criteria:

• One proximal lesion in a primary molar.
• Radiographic evidence of caries extending at least into the inner half of the enamel but not the inner half of dentin.
• Proximal contact with adjacent healthy or restored teeth.
• Occlusal contact with opposing healthy or restored teeth.
• No indication for pulp therapy or other restorative treatment.
• A predicted survival until exfoliation of 2 years.

Exclusion Criteria:

• Radiographic evidence of caries extending into the inner half of dentin.
• No proximal contact with adjacent healthy or restored teeth.
• No occlusal contact with opposing healthy or restored teeth.
• Tooth indicated for pulp therapy or other restorative treatment.
• A predicted survival until exfoliation of less than 2 years.