The delivery of orthodontic care in New Zealand. Part I: Analysis of a census of orthodontists.

A two-part study was undertaken to determine the supply of orthodontic services in New Zealand. Part I focuses on services supplied by specialist orthodontists. A companion paper will describe the amount and characteristics of orthodontic services supplied by dentists. All orthodontists in New Zealand in 1999 were surveyed to provide information on practice location and days practiced in 1996 (the year of the last population Census), and the amount and type of orthodontic treatment carried out in the year 1 July 1998 to 30 June 1999. The response rate was 78.9 percent. Data from 1996 were used to establish and quantify the location and distribution of orthodontists in New Zealand, and their spatial relationship to 12-year-olds and 10- to 14-year-olds using Geographic Information Systems. The information from 1998-1999 was used to determine the amount and variety of services provided by orthodontists and the makeup of their patient base. Nearly two-thirds of orthodontists had a branch practice. Over 50 percent of the 10- to 14-year-old population resided within 5 km of an orthodontist, and nearly three-quarters within 10 km. Disparities between regions existed in the supply of specialist orthodontic services. The catchment areas of main urban areas had more than three times the supply of orthodontists to 12-year-olds than did the secondary and minor urban areas combined. The mean average active patient load was 371, and the mean number of full upper and lower fixed appliances placed was 130.3 during the year of the study. Nearly half of all patients had been referred from dentists, approximately one-quarter were self-referred, and a quarter had been referred by dental therapists. Adults comprised 12.1 percent of the patient load of orthodontists; 60 percent were female.