A Brief History of Clinical Trials with Fluoride Topicals

Clinical evaluation of fluoride topical solutions, as caries-preventive agents, began in the early 1940s. These anti-caries trials typically involved high strength sodium fluoride solutions that were professionally applied one to four times a year to the erupted teeth of school age children. Results, calculated as a percentage reduction in new decayed, missing or filled teeth (DMFT) or surfaces (DMFS) in the fluoride-treated group compared to a control group, generally ranged from 20% to 60% reduction, with an average reported reduction of about 30% for the high potency fluoride topicals. Anti-caries trials with adult patients have been more limited than those with children, yet published results do demonstrate that topical fluoride application to the permanent teeth of adults can be beneficial against coronal caries and root surface carious lesions.

In response to the success demonstrated by the early clinical studies, topical application of aqueous sodium fluoride began to be used routinely by the dental profession at large beginning in the late 1940s. As supporting clinical data became available in the 1950s, dentists also started applying freshly-prepared 8-10% solutions of stannous fluoride. By the 1960s, continued fluoride research resulted in the development of a new topical preparation, acidulated phosphate fluoride (APF). Soon after this discovery, dental manufacturers began supplying the profession with solutions containing 1.23% fluoride ion in a 0.1 molar phosphoric acid buffer with a pH between 3.0 and 4.0. The traditional "paint on" technique, where only one or two quadrants at a time are isolated, dried and treated was found to be time-consuming. For this reason, other vehicles for APF were sought that could be more easily applied in a program of professional topical fluoride application. Eventually, APF became available commercially as a gel. Gels had the advantage of being used in disposable trays so that the entire mouth could be treated in a single application. Clinical studies in the late 1960s provided support for the anticaries effectiveness of these new fluoride gels.

In a parallel fashion to the evolution of in-office fluoride preparations, procedures for the self application of fluoride were developed in the early 1960s. The investigation of self-application techniques was prompted by their need in public health programs. It was recognized that not all children had access to fluoridated water supplies, and that office treatments can be costly and time-consuming for certain other patient groups. Significant caries reduction with self application of topical sodium fluoride gels, delivered by either mouth trays or tooth brushing, was adequately demonstrated in a number of school-based programs. Also, the anti-caries benefit of sodium fluoride mouth rinses was extensively documented. In total, a wide variety of fluoride gels and rinsing solutions, with different treatment regimens, were evaluated. The most efficacious formulations included a high frequency 1-2% sodium fluoride gel, delivered by mouth trays or by tooth brushing, and a daily (0.05%) and a weekly (0.2%) neutral sodium fluoride mouth rinse. In the public health studies, the fluoride formulations were generally prepared by the clinical investigators. The anti-caries success of such preparations, however, led to the commercial development of comparable products for regular home use by individual patients. It should be noted that, at this point, the major emphasis of public health officials, and the dental profession, was on the control of dental caries in children and not on plaque or periodontal disease control.