Variation in restoration survival rates among individual dentists

Dental treatment within the General Dental Services (GDS) is administered in England/Wales by the NHS Business Services Authority (Dental Service Division (DSD)), which holds detailed treatment records.

Objectives: This study reports the variation in one-year restoration survival rates between 382 dentists practising in the West Midlands region of England.

Methods: For this study, the data were restricted to patients aged between 40 and 59 years, and to dentists practising within the West Midlands Strategic Health Authority who placed >200 MO or DO restorations in the 2 years to 30 March 2007. For each direct restoration placed, the subsequent history of that tooth was consulted and one-year survival to next intervention calculated using Kaplan-Meier survival analysis. Variation between the dentists was tested by a Log-Rank test. A similar analysis was carried out on MOD amalgam and resin composite restorations by the same dentists and the results correlated against those for MO/DO restorations.

Results: 382 dentists fulfilled the inclusion criteria. They placed over 120,000 MO/DO amalgam restorations. For these restorations, the dentists' survival rates were significantly different, and the distribution was skewed, with the highest frequency occurring at 92% survival but with survival rates as high as 100% and as low as 64% being recorded. A similar pattern emerged for composite restorations, although three dentists recorded survival rates of less than 50%. For MOD amalgams, the survival function histogram was flatter than for MO/DO restorations. One-year survival for MO/DO restorations was significantly correlated with survival for MOD (r=0.805) and survival for composite restorations (r=0.491).

Conclusion: For a sample of UK dentists, there is substantial variation in the survival of restorations that they placed in a two-year period, and significant correlation between dentists' restoration survival for different types of direct restoration.

Acknowledgment: The support of the BSA (DSD) is acknowledged.