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significant differences were observed, they were small in absolute terms, with no consistency as to which group was superior. These studies had relatively small sample sizes, but taken together they provide strong evidence that hygienists can, in a relatively short period of time, be trained to provide such irreversible procedures as Classes I, II, and III restorations at a level that is comparable with that of dentists. [Classes I, II, and III refer to the specific teeth and surfaces being restored (i.e., a Class II restoration is on proximal surfaces of molars or premolars).] Of the 13 other empirical studies, 3 were early evaluations of the Alaskan Dental Health Aide Therapist (DHAT) program; 3 were conducted in Canada, where therapists practice in remote tribal areas, and in the 1970s, Saskatchewan established a short-lived school-based system; 3 studies were conducted in Australia, where therapists have practiced, with state variation, since the 1960s; 2 were conducted in the United Kingdom, where therapists have also been practicing to various degrees for some time; and the last was the result of another U.S. fact-finding trip to New Zealand. Taken as a whole, this body of work, like the set of experiments conducted in the 1970s, provides strong evidence of the ability of dental therapists, working in several settings and systems, to prepare and place restorations at an acceptable level—indeed, at a level that is at least comparable with that of dentists working in the same settings. In fact, of these reports, only one drew negative conclusions. At the behest of the (then) 2 California dental associations, a team went to New Zealand in the early 1970s to gather information, since, at the time, California was considering a schoolDownloaded from jdr.sagepub.com at UNIV OF MICHIGAN on May 24, 2013 For personal use only. No other uses without permission. © International & American Associations for Dental Research 3 vol. XX • suppl no. X JDR Clinical Research Supplement Table. Report or Study Discussing the Technical Quality of Care Provided by Non-dentists Preparing and Placing Restorations Author Date Country Type of Study Overall Conclusion Gruebbel 1950 New Zealand Observational Critical of the program based on the high incidence of caries, the nurses’ training, their quality of work, and the “socialist” nature of the system. Bradlaw et al. 1951 New Zealand Observational New Zealand nurses exhibit a high standard of technical efficiency in the treatment of children. Fulton 1951 New Zealand Observational New Zealand dental nurses are capable of producing amalgam restorations of high quality. General Dental Council 1966 United Kingdom Empirical Dental auxiliaries are well-trained to carry out simple amalgam restorations; the quality of clinical work is high. Dunning 1972 Australia, New Zealand Observational General impressions were that the quality of work in both countries was good. Friedman 1972 New Zealand Observational Found the technical quality of treatment to be quite high. Redig et al. 1973 New Zealand Empirical A New Zealand-type dental nurse would not be acceptable to Californians. Roder 1973; 1976 Australia Empirical The quality of restorations placed by the school dental service was good. Powell et al. 1974 United States Experimental If the samples of dental therapist trainees and junior dental students are representative, there is no difference in their performance on the procedures evaluated. Spohn et al. 1976 United States Experimental Dental hygienists performed at a level comparable with that of senior dental students for specific procedures. Ambrose et al. 1976 Canada Empirical The quality of services was at a generally high level. Sisty et al. 1978 United States Experimental The dental hygiene students were able to perform selected operative and periodontal procedures at a level comparable with that of senior dental students. Swallow et al. 1978 Netherlands Experimental No specific conclusions reported with regard to technical competence (it was not the main focus of the study). Lobene