The purpose of the study was to undertake analyses of treatment data for the Personal Dental Services (PDS) of Lambeth, Southwark and Lewisham Primary Care Trusts and relate the analyses to the PDS goals of supporting practitioners deliver appropriate quality dental care and ensuring that appropriate quality safety net services are available for all residents.Analyses of treatment data provided by the Dental Practice Board were undertaken for the post-PDS period (February 1999–March 2003, based on data availability). Analyses of the clinic notes for 1500 patients were also undertaken for the 1 year pre-PDS period (October 1997–September 1998) and post-introduction of the PDS (October 1998–June 2003). Two sets of analyses were undertaken to evaluate trends in treatment claims for the Dental Practice Board data, absolute numbers of each type of treatment claimed each month and change in numbers of types of treatments claimed over time. The clinic notes were used to undertake post-PDS, pre-PDS comparisons of the number of treatment items and grouped treatment item categories undertaken and the number of courses and percentages of private treatment items provided. The following sociodemographic characteristics of the patients were also analysed, age, gender, exemption status and attendance status.Overall it was identified that the percentage reduction in the number of treatment items undertaken was 13% (95% CI−19%,−7%), post- as compared to the pre-PDS introduction period. On an annual basis it was identified that the percentage reduction in the number of treatment items undertaken per year per patient post-PDS was 4% (95% CI−6%,−2%). There were significant variations in the impact of the PDS on the number of treatment items undertaken for different types of patients. A limited number of treatment types changed significantly post- as compared to pre-PDS. The proportion of exempt patients treated did not increase post-PDS.It is possible that a less invasive style of dental treatment was provided during the course of the PDS, however, there was only limited evidence to indicate that dentists practice style changed based on types of treatment categories provided. The PDS provided a limited safety net service for local residents. In setting program goals the nature of quality dental practice requires definition and evaluation should be undertaken on a prospective basis. [ABSTRACT FROM AUTHOR]