Randomised clinical trial of four dental restorative materials (silver amalgam 'Dispersalloy', compomer 'Dyract AP', resin modified glass-ionomer 'Fuji IL LC' and Vitremer') placed in children
This study measures the one and two-year survival rates of restorations used to restore occlusal and approximal cavities of primary teeth, and occlusal cavities in the first permanent molars and premolars of children. Restorations were carried with / or without the use of local anaesthesia. The materials used were 'Dispersalloy', 'Dyract AP', 'Fuji II LC and 'Vitremer'. The unit of study was the individual tooth. A total of 288 restorations were placed and the teeth were randomly allocated to one of the four restorative materials. Following a standardised inclusion criteria, two groups of children took part in the clinical trial. In the first group, children and adolescents were recruited from the Caries Clinic of the Department of Paediatric Dentistry of the Eastman Dental Hospital. The mean age was 7.8 years. A total of 157 restorations were placed in 60 children. In the second group, children and adolescents of the United Arab Emirates were recruited from their Primary School Dental Clinic. The mean age was 7.3 years and 131 restorations were placed in 92 children. Caries diagnosis was carried out by both direct and tactile examination. Teeth with gross multi-surface caries and/or developmental enamel defects were excluded from the trial. All operative work was performed in a standard dental clinic environment. Rubber dam isolation was used whenever possible. High volume suction and a saliva ejector were used as an alternative. Cavity designs for both amalgam and resin restorations were based on a minimal intervention technique. Conventional high-speed and low-speed handpieces were used. The manufacturers' instructions in the placement of resin restorations were followed. Direct (in vivo) clinical assessment of all restorations was carried out following the modified Ryge criteria at baseline and after 6, 12 and 24 months. Clinical Photographs were used whenever possible. Indirect (in vitro) assessment of all the restorations using stone cast replicas was carried out using a modification of the Leinfelder cast rank ordering method. Restoration assessments and review appointments were made at 6, 12, 18 and 24 months from baseline respectively. Results showed that there was no significant difference between the four restorative materials tested over the 24 months trial period. Restoration failure was recorded in 10% of the 288 originally placed restorations (10 Amalgam, 9 Dyract AP, 7 Fuji II LC, 4 Vitremer) and was primarily due to bulk fracture and recurrent caries during the 12-18 months' review period. Marginal discolouration was present in 52% of the restorations by the end of the 18-month review period. After 2 years, 89% of restorations appeared to be discoloured. There was a significant difference between the UK group and UAE group in restoration survival. More restorations at the UAE needed replacement (P < 0.001) compared with those in the UK. The in vitro assessments of cast replicas showed evidence of marginal wear of the restorative material over time. The median wear change was 75pm -125 pm during the 18 -24 months' review period. In an attempt to calculate the in vitro volumetric (bulk) material loss, a pilot study was carried out using a light-body impression material and polyvinyl stent copings. The thickness of the impression material corresponded to the quantitative measure of over all material wear. The results of the pilot study were unsatisfactory, as reproducible values were only achieved at levels where the restoration was deemed to have failed.