Evaluation of cavity wall adaptation of bulk esthetic materials to restore class II cavities in primary molars

The purpose of the study was to assess the cavity wall adaptation and gap formation of a bulk fill composite resin and reinforced conventional glass ionomer cement and a resin-modified glass ionomer cement in class II restorations on primary molars. Standardized class II slot cavity preparations were prepared in exfoliating primary molars. Teeth were restored with one of the three tested materials (n = 10): SonicFill bulk fill composite resin (SF), EQUIA Fil conventional reinforced glass ionomer cement (EQF), and Vitremer resin-reinforced glass ionomer cement (VT). Cavity wall adaptation of the restorations was investigated by computerized X-ray micro-tomography and the percentage void volume fraction (%VVF) was calculated. Same specimens were sectioned and the interfaces were evaluated by reflection optical microscopy to measure the percentage linear length (%LD) of the interfacial gaps. Samples were further evaluated by environmental scanning electron microscopy (ESEM). EQF and SF showed significantly lower %VVF and %LD values than VT (p < 0.05). This was in accordance with ESEM findings where VT illustrated extended interfacial gaps. SF and EQF showed better cavity wall adaptation than VT in class II restorations on primary molars. High-strength conventional glass ionomer cement (GIC EQF) and bulk fill composite SF requiring fewer application steps and reduced operating time than the traditional composite resin materials showed good cavity wall adaptation. Short operating time and good cavity wall adaptation are advantages of the materials in restorative and pediatric dentistry, especially while working on children with limited attention span.