Performance of restorations in primary molars over a seven-year period.

Objective: The aim of this study was to evaluate the use and reintervention rate of fillings compared to preformed metal crowns in the everyday clinical practice of German dentists.

Methods: In this retrospective, longitudinal analysis, fee codes from the Kassenzahnärztliche Vereinigung Westfalen-Lippe for restorations placed in primary molars between 2012 and 2015 in children until 7 years of age followed for a 7-year period (latest until December 2022) were filtered and analyzed with the Fine and Gray competing risk regression and Cox proportional hazards regression to calculate the risk of reintervention divided into the main outcomes "Successful", "Minor Failure/Repair" and "Major Failure/Endodontic Treatment/Extraction". 367,139 primary molars (one-surface fillings: n = 117,721; two-surface fillings n = 198,815; three-surface fillings n = 36,695; more than three-surface fillings n = 8,267 and preformed metal crowns n = 5,641 were included in this study.

Results: Teeth treated with preformed crowns needed significantly less re-interventions. Subdistribution hazard ratio for minor events was 0.117 (95 %-CI: 0.097 to 0.141) and hazard ratio of major events (HR=0.786; 95 %-CI: 0.695 to 0.890) when compared to one-surface fillings in multivariable adjusted analysis. Within 7-year follow-up preformed crowns required less repairs (80.6 % success rate, minor failure 4.4 %, major failure 16.3 %) than the teeth treated with composite fillings (46.2 %-52.6 % success rate, minor failure 27.0 %-39.5 %, major failure 15.5 %-28.4 %, p < 0.001).

Conclusion: Within the German healthcare system fillings are the first choice for treating primary molars despite considerably higher reintervention rates. This encourages a discussion on the indication of fillings and the more durable preformed metal crowns to reduce unnecessary reintervention in young children.

Clinical Significance: This study gives an unprecedented insight into the German healthcare system regarding the reintervention rates of the most relevant treatment techniques for caries in primary molars.