2 QUINTESSENCE INTERNATIONAL | volume 50 • number 1 • January 2019 A randomized controlled clinical trial of glass carbomer restorations in Class II cavities in primary molars: 12-month results Azza A. El-Housseiny, BDS, MSc, PhD/Najlaa M. Alamoudi, BDS, MSc, DDS/Sumaya Nouri, BDS, MSc/ Osama Felemban, BDS, DScD Objective: To evaluate the clinical performance of Glass Car- bomer (GC) (GCP Dental) in restoring Class II cavities in primary molars in comparison with resin-modified glass-ionomer ce- ment (RMGIC) and composite resin (CR) restorations. Method and materials: Healthy children aged between 4 and 8 years with a proximal lesion in at least one primary molar were re- cruited from the Pediatric Dental Clinics. A sample of 162 mo- lars was randomly assigned to one of the following restoration types: GC, RMGIC, and CR. The restorations were evaluated clin- ically using the Cvar and Ryge criteria at 6 and 12 months post- operatively. Results: At 12 months, the success rates of ana- tomical form and marginal adaptation were 67% and 54% for GC, 98% and 93% for RMGIC, and 98% and 98% for CR, respec- tively. The GC restorations were significantly less successful than RMGIC and CR restorations in terms of anatomical form (P < .001) and marginal adaptation (P < .001). Secondary caries formation was not observed in any of the restorations in the three restorative material groups. Conclusion: The 12-month clinical performance of the GC restorative material was not sat- isfactory in restoring Class II cavities in primary molars. RMGIC and composite resin restorations performed significantly better. The use of GC cannot be recommended for restoring Class II cavities in primary molars. (Quintessence Int 2019;50: 2–12; doi: 10.3290/j.qi.a42573) Key words: composite, Class II, glass carbomer, glass-ionomer cement, primary molars Successful restoration of Class II cavities in primary molars can be considered challenging. Factors such as the level of cooper- ation of the child and the handling properties and setting time of the restorative material may influence the success rate of the restoration. 1 Composite resin (CR) restorations are tech- nique-sensitive, and their success depends greatly on the skill level of the operator. 2 In addition, studies have identified that a few of the components of composite resin filling materials are cytotoxic and harmful. 3,4 Glass-ionomer cement (GIC) is known to have a number of potential advantages over other restorative materials including fluoride release, chemical bonding to tooth structure, and bio- compatibility. 5 In the literature, there is evidence that RMGIC is successful in restoring small to moderate Class II cavities. 6 How- ever, it remains important to remember that RMGIC contains cytotoxic monomers rendering it a less biocompatible option. 7 Hydroxyapatite (HA)-enhanced GIC was introduced in the 1980s by Yamamoto. 8 Since then several studies targeted the assessment of the effect of adding HA to conventional GIC restorative materials. 9 Studies have shown that the addition of the HA particles to the glass ionomer powder can increase the fracture toughness of the cement 9,10 and improve its flexural strength and microstructural properties. 11 Glass Carbomer (GC; GCP Dental) is a commercially available, monomer-free restorative material that contains nano-sized par- ticles of HA and fluorapatite (FA) as secondary fillers in addition to the carbomised fluor-aluminum silicate nano-glass particles. 12 The reactive glass is activated with dialkyl siloxane as described RESTORATIVE DENTISTRY