Which filling material is best in the primary dentition?

The Cochrane Oral Health Group's specialised trial register (Cochrane Central Register of Controlled Trials) was searched along with Medline, Embase and the System for Information on Grey Literature in Europe, along with proceedings from conferences on early childhood caries, restorative materials for paediatric dentistry, and material sciences conferences for dental materials used for children's dentistry. There were no language restrictions. Additionally, the reference lists from articles of eligible papers were searched, and handsearches made of the journals Operative Dentistry, Journal of Restorative Dentistry, Pediatric Dentistry, Journal of Clinical Pediatric Dentistry, and the International Journal of Paediatric Dentistry. Authors and manufacturers of dental materials were individually contacted.

Randomised controlled trials (RCT) or quasi-RCT with a minimum period of 6 months' followup were included. Both parallel group and split-mouth study designs were considered. The unit of randomisation could be the individual, group (school, school class, etc), tooth or tooth pair. Included studies had a dropout rate of less than 30%. The eligible trials consisted of young children (children aged less than 12 years) with tooth decay involving at least one tooth in the primary dentition which was symptomatic or symptom-free at the start of the study.

Data were independently extracted, in duplicate, by two review authors. Disagreements were resolved by consultation with a third review author. Authors were contacted for missing or unclear information regarding randomisation, allocation sequence, presentation of data, etc. A quality assessment of included trials was undertaken. The Cochrane Collaboration statistical guidelines were followed for data analysis.

Only three studies were included in this review. One study assessed the clinical performance of aesthetic crowns versus conventional stainless steel crowns in 11 children who had at least two mandibular primary molars that required a crown restoration. The outcomes assessed at 6 months included gingival health restoration failure occlusion, proximal contact and marginal integrity. The second (split-mouth) study compared a resin-modified glass ionomer with amalgam over a 36-month period. Forty pairs of Class II restorations were placed in 40 patients (21 males and 19 females; mean age 8 years +/-1.17 years). Although the study period was 36 months, only the 6- and 12-month results are reported because of the loss to followup of patients being greater than 30% for the 24- and 36-month data. The third study recruited 30 patients (age range, 4-9 years) with one pair of primary molars that required a Class II restoration. The materials tested were a compomer and amalgam. Loss to followup at 24 and 36 months was 20% and 43% respectively. This meant that only the 24-month data were usable. For all of the outcomes compared in all three studies, there were no significant differences in clinical performance between the materials tested. No studies were found that compared restorations with extractions or with no treatment as an intervention in children with childhood caries.

It was disappointing that only three trials that compared three different types of materials were suitable for inclusion into this review. There were no significant differences found in all three trials for all of the outcomes assessed. Well-designed RCT comparing the different types of filling materials for similar outcomes are urgently needed in dentistry. There was insufficient evidence from the three included trials to make any recommendations about which filling material to use.