Background: Dental composites are popular restorative material. The success of these restorations depends on many factors.

Objectives: The purpose of this study was to investigate the reasons for replacing composite restorations in patients who had referred to Babol dental school during years 2013 and 2014.

Patients and Methods: Age, sex, type of occlusion, DMF, existing parafunction, type of tooth, class and reason of composite restoration replacement was recorded for patients who had referred to the Babol university of dentistry during years 2013 and 2014. Data analysis was done using descriptive statistical analysis.

Results: Among 242 patients, there were 56 (21.3%) males and 186 (70.7%) females. More than half of the patients were aged between 20 and 30 years old (51.7%), and had class Ι dental occlusion (63.1%). The mean DMF was 9.4 ± 2.8. Upper incisors were the most frequent teeth group for replacement of composite restorations, commonly due to secondary caries. Major causes for composite restoration replacement were secondary caries. The most common composite restoration replacements were class II restorations. Secondary caries was the most prevalent cause in class II MO / DO (20 cases (34.4% with secondary caries)).

Conclusions: The most common cause of restoration replacement in patients referred to the Babol university of dentistry during years 2013 and 2014 was secondary caries that were found in Class II restorations.