An investigation of factors influencing the longevity of restorations in primary molars.

The treatment records of three dentists working in south-east England were screened and 361 chosen for the investigation of the longevity of restorations placed in primary molars. The analysis was carried out using an independent sampling technique, i.e., one restoration per patient. The median survival time for all the restorations was 70.6 months (standard error +/- 3.7 months). The survival pattern of the restorations for the three dentists was different and therefore the influence of six factors on the life-span of restorations was investigated using the Cox regression model. There was no evidence that the life-span of the restorations depended on the sex of the patients (p = 0.506), or the type of primary molars being treated (p = 0.776); there was weak evidence that the life-span depended on the caries susceptibility of the patient (p = 0.151) and preformed metal crown restorations (p = 0.106); there was good evidence that the life-span depended on the age of the patients at the time of treatment (p = 0.016), whether pretreatment radiographs had been taken (p = 0.023) and type of amalgam restoration (p = 0.003).