This article complies a survey on the replacement of the posterior restorations and accesses possible factors that influence the replacement of posterior restorations.

The data was collected from patients that visited department of conservative dentistry from Dec 1st 2003, to Sep 3rd 2004. Teeth was restricted to posterior permanent teeth. 9 dentists recorded age, gender of patients, tooth location, cavity form and restorative material. They rated marginal adaptation, anatomic form, secondary caries of old restoration by modified Ryge criteria system. The statistical analysis was performed with Chi square test (p < 0.05) for replacement ratio according to patients, tooth factor and One-way ANOVA was performed for comparison of old restoration according to restorative material.

The results were as follows;

1. The female (62%) was statistically higher ratio than the male (38%).

2. The distribution of replacement case according to age, the rate of replacement was in descending order, 20's (38.3%), 40's (16.8%), 30's (15.9%), 10's (11.1%), 50's (9.2%), 60's (8.7%).

3. The rate of replacement was 88% for molar and 12% for premolar (p < 0.05).

4. The rate of replacement was 39% for maxillar and 61% for mandible (p < 0.05).

5. The material of restorations was amalgam (69%), gold inlay (17%), composite resin (13%).

6. In rating system by modified Ryge criteria system on margin adaptation, there was statistically significant difference between amalgam and gold inlay. But on anatomic form and caries, there was no statistically significant difference among the material of restorations.