Class II Composite Resin Restorations In Danish And Norwegian Adolescents

Method: The study had a prospective, non-randomized design and comprised consecutively performed routine treatments. 

Result: From 2001-2004, a total of 3470 Class II composite resin restorations were placed in patients aged 5-17 years by 32 dentists in the Public Dental Health Service (PDHS) in Denmark (DK) and 26 dentists in the PDHS in Norway (N). Of the restorations, 556 were placed in 444 Danish patients and 2914 were placed in 1423 Norwegian patients. Primary caries was reason for placement in 94% DK and 93% N. The restorations were followed up to 6.8 years (DK) and 8.4 years (N). During the individual follow-up, 63 DK and 276 N restorations failed. Secondary caries was the main reason for failure in 59% DK and 74% N. Mean annual failure rate was 3.5% in total; 4.2% DK and 3.3% N. In multiple Cox models, significantly higher hazard for failure were found for restorations placed in Denmark vs. Norway (p<0.001),  patients with high caries experience at twelve years age (p=0.007), medium and poor compared with good oral hygiene (p=0.007), pulpal symptoms prior to placing the restoration (p=0.03), restorations without gingival enamel limitation (p=0.04), restorations in second- vs. first molars and premolars (p=0.03) and saucer-shaped vs. traditional Class II preparations (p<0.001). ANOVA tests showed that the covariates were significantly different distributed according to country.

Conclusion: International differences were detected; slightly higher failure rate was found for Danish compared with Norwegian Class II composite resin restorations. In addition, patient’s caries experience, oral hygiene, symptoms, tooth type, and enamel limitation and preparation technique of the restorations were significantly related to longevity of the restorations. Secondary caries was the main reason for failure in both countries.