According to Kuhn,⁹ a paradigm shift for a provider is not gradual; it is all-or-nothing. For the profession as a whole, it can be a long-term process that begins when dentists realize that the old paradigm (in this case, the surgical model) no longer adequately addresses the problems facing the profession, and it progresses as more and more evidence supporting the new paradigm (the medical model) appears in the literature. Kuhn’s model of paradigm shift suggests that financial reimbursement alone may not increase dentists’ adoption of fluoride varnish.

The evidence in medicine indicates that while financial incentives can influence physicians’ treatment behavior, little is known about whether financial incentives can increase the delivery of preventive services.¹⁰ In the United Kingdom, a physician bonus system plus other interventions (such as computer recall systems, guidebooks and hiring immunization coordinators) significantly increased immunization coverage levels.^11,12 One U.S. study showed that bonuses, enhanced fees and feedback increased physicians’ chart documentation of immunization among children in the Medicaid program, but they did not change physicians’ behavior.¹³ Similarly, financial incentives and feedback did not increase physicians’ compliance with cancer-screening guidelines in a Medicaid health maintenance organization.¹⁰ In a dental public health program designed to increase access to preventive dental services for children in the Medicaid program who were younger than 5 years of age, dentists received enhanced dental fees and continuing dental education, and outreach staff from the local health department recruited families for and enrolled them in the program.¹⁴ In the program’s first year, 37 percent of the enrolled children had made at least one dental visit, compared to 12 percent of children not enrolled in the program. To the best of our knowledge, no published study has examined whether insurance coverage can increase dentists’ adoption of new preventive technologies.

In summary, the theoretical and empirical evidence is equivocal about whether the introduction of fluoride varnish use as a covered benefit will increase dentists’ adoption of the technology. The aim of our study was to determine whether general dentists’ adoption of fluoride varnish use increased after WDS added the service as a covered benefit in January 1996.

	METHODS

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Study design and sample. We used a pretest-posttest design to determine whether reimbursement increased dentists’ use of fluoride varnish. In 1995, we performed a systematic random sampling of general dentists in Washington state, selecting every sixth name from the current list of licensed dentists in the state, after eliminating specialists who were not general practitioners. We surveyed 532 general dentists in Washington state by mail to assess dentists’ adoption of the medical model of caries control in everyday practice.³ In the 1997 survey, we used the same sample. After eliminating ineligible subjects identified in the original survey, we asked 460 general dentists to complete the 1997 questionnaire.

Questionnaire. We based the 1997 questionnaire on the one we used in the 1995 survey, but modified it to reduce its complexity and encourage participation. The survey focused on the use of fluoride varnish for caries control among adult patients, as well as two other caries control services: use of chlorhexidine rinses for caries control and use of pit-and-fissure sealants in adults. For each caries control service, dentists were asked about current use and the year they began providing the service. They were asked about their sources of new knowledge and their attitudes toward fluoride varnish. The questionnaire included items on practice characteristics, continuing education, memberships in dental societies and the role other dentists played as the source of information about new technologies and products. The questionnaire contained 48 questions, many with subparts. (A copy of the questionnaire may be obtained from the corresponding author.)

The theoretical and empirical evidence is equivocal about whether the introduction of fluoride varnish use as a covered benefit will increase dentists’ adoption of the technology.

Survey procedure. The survey methodology followed the procedures in the 1995 survey recommended by Dillman.¹⁴ In December 1997, we mailed each dentist a questionnaire, a cover letter, a prepaid return envelope and a $5 cash incentive. The initial mailing was followed by a reminder postcard; a second mailing of the questionnaire and a revised cover letter; a third mailing of the questionnaire and a revised cover letter; and follow-up telephone calls to the offices of nonrespondents by the dentist investigator (L.F.). The total data collection period was 15 weeks.

Data analysis. We used descriptive statistics to analyze data according to selected dentist characteristics. We constructed dentist adoption curves for use of fluoride varnish, chlorhexidine rinses for caries control, and adult pit-and-fissure sealants and compared them visually to the adoption curves constructed in the earlier study. A difference in proportions test¹⁵ was used to compare dentist adoption rates for the three caries control services. Bivariate statistical tests identified practice characteristics, dentist characteristics and forms of communication associated with adoption of fluoride varnish. Descriptive statistics were calculated to determine dentists’ sources of information about the preventive service. The results of the significance tests are reported before and after the Bonferroni adjustment.

	RESULTS

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Response rate. Of the original sample of 460 dentists, 96 were ineligible because they had retired (30), were not in general practice during any part of 1997 (44), could not be located (20) or were deceased (two). From the revised sample of 364, there were 258 usable returns, for a 70.9 percent response rate. Among these respondents, 211 (81.8 percent) also completed the 1995 survey.

Demographic characteristics of sample. Dentist respondents were mostly male (88.3 percent) and white (87.2 percent). The majority of them had been graduated from the University of Washington Dental School (58.5 percent); the median year of graduation was 1976. The respondents saw patients a mean of 34 hours per week.

Adoption curve for fluoride varnish. Figure 1 presents dentist adoption curves for fluoride varnish from the 1995 and 1997 dentist surveys. The 1995 survey revealed that about 5 percent of general dentists reported regular use of fluoride varnishes in 1980; this percentage increased to 32 percent by 1995. The dentists who responded to the 1997 survey had a similar pattern of adoption. Less than 5 percent of the dentists reported using fluoride varnish regularly in 1980, but 44 percent reported such use by 1997 (P = .004).

View larger version (48K): [in this window] [in a new window]   Figure 1. Dentist adoption curve for fluoride varnishes: 1995 and 1997 survey results.

We also assessed the reliability of the adoption self-reports among dentists who responded to both surveys. Among dentists who reported regular use of fluoride varnish in 1995, about 67 percent also reported regular use of fluoride varnish in 1997. The correlation between dentists’ reported year of adoption of varnish use in the two surveys was .58.

Adoption curves for other services. Figures 2 and 3 compare the adoption curves for, respectively, use of chlorhexidine rinses for caries control and use of adult pit-and-fissure sealants from the 1995 and 1997 surveys. Virtually no change occurred in dentists’ adoption of these two technologies between 1995 and 1997.

View larger version (50K): [in this window] [in a new window]   Figure 2. Dentist adoption curve for chlorhexidine rinse for caries control: 1995 and 1997 survey results.

View larger version (48K): [in this window] [in a new window]   Figure 3. Dentist adoption curve for adult pit-and-fissure sealants for caries control: 1995 and 1997 survey results.

Dentists were asked questions about 37 variables theoretically linked to time of adoption (that is, early vs. later) of fluoride varnish use. Table 1 presents the variables that yielded significant findings. Early adopters, for example, were more likely to enjoy experimenting with new procedures. They also were more likely to have friends and acquaintances who were using the service. Early adopters were more likely to report that other dentists sought their advice and were themselves more likely to ask other dentists for advice.

Sources of information for fluoride varnish users. Dentists were asked to indicate from what sources they obtained information or advice when deciding whether to adopt fluoride varnish use into their practice. Adopters indicated professional journals (49 percent), professional newsletters (45 percent), continuing education courses (43 percent), and conferences and seminars (34 percent) as their most frequently used sources.

Association between knowledge and use of fluoride varnish. Dentists were provided 29 true statements relating to fluoride varnish use in adult patients and were asked to indicate the extent of their agreement or disagreement with them. Statements centered on dental health, finances, office and personnel, patients and practice. Fluoride varnish users, as a whole, were in agreement with one-half again as many of the statements as were nonusers (20 vs. 13; P = .00), and early adopters had more correct knowledge about fluoride varnish than later adopters (20 vs. 15; P = .00.)

Reasons for not using procedures. Dentists who did not use fluoride varnishes on a regular basis—176 of 275 (64 percent)—were asked to indicate their three most important reasons for not doing so (Table 2). Among these dentists, 26 percent said they were not aware of the existence of the service. An additional 11 percent indicated an awareness of the service but were unaware of the cost:benefit ratio, and 25 percent that they were not convinced of an advantageous cost:benefit ratio. Patients’ rejection of the service was indicated by 23 percent of respondents. For 27 percent of nonadopters, cost—in the form of lack of insurance coverage—was reported as one of the three most important reasons for not using fluoride varnishes regularly. Nearly 23 percent of nonadopters were not motivated to use the service for various reasons, including availability. Lastly, 24 percent indicated their patients to be at insufficiently high risk of developing caries to justify its use.

	DISCUSSION

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Our findings indicate that financial reimbursement and other factors have increased dentists’ adoption of fluoride varnish use, but reimbursement by itself is not enough to solve the problem of dentists’ low rate of use of innovative caries control services. Two years after WDS added fluoride varnish use as a reimbursable service in many of its insurance programs, less than 50 percent of general dentists in Washington state regularly used fluoride varnishes for adult caries control. Although economic theory would suggest otherwise, this finding is consistent with Kuhn’s⁹ paradigm shift model, as well as with evidence that preventive technologies diffuse more slowly than reparative treatments.

The impact of reimbursement on fluoride varnish use may be influenced by the number of patients within individual practices enrolled in a WDS plan. WDS has about one-third of the dental insurance market in Washington state, and 82 percent of all general dentists in the state are WDS providers. Thus, WDS reimbursement for fluoride varnish may have little influence on dentists who neither are WDS providers nor have many WDS patients.

Nevertheless, the evidence indicates that dentists’ awareness and adoption of fluoride varnishes has increased since 1995. About 74 percent of respondents are aware of fluoride varnish and its benefits against caries development, compared with 58 percent in 1995. In the six years since fluoride varnish received FDA approval for marketing in the United States as a medical device, it has become readily available to U.S. dentists. Prominent display advertising for the product is beginning to appear in professional journals.¹⁶ The 1995 survey itself may have increased dentists’ awareness of fluoride varnish, and our subsequent article in JADA³ also may have had an educational benefit among dentists. Nonadopters, however, appear not yet convinced of the cost:benefit ratio, continue to see cost as a barrier and fail to see the clinical rationale for varnish use in adults.

The adoption curve for fluoride varnish use indicates a sharp rise in employment of the procedure, from 32 percent in 1995 to 44 percent in 1997. It appears from the shape of the curve that dentists are currently in the take-off phase for this service, and that the community may see a higher percentage of adopters in the future. The fact that dentists’ adoption of fluoride varnish increased, but that no changes in dentists’ adoption patterns were observed for use of either chlorhexidine rinses for caries control or adult pit-and-fissure sealants, also indicates that reimbursement and other factors—such as dentists’ communication patterns—are increasing dentists’ adoption of the new technology. Our study cannot measure the magnitude of the relative contribution of each of these factors, or whether the synergistic influence of both factors has caused the changes in awareness and use.

The evidence indicates that dentists’ awareness and adoption of fluoride varnishes has increased since 1995.

In future studies, measures of dentists’ adoption of new technologies may be constructed either from dentists’ self-reports of their behavior or from dental claims. The 1995 and 1997 adoption curves in Figures 1, 2 and 3 were constructed from dentists’ self-reports in the two surveys. Among those who participated in both surveys, the modest correlation (r = .58) between the two self-reports for year of adoption may reflect the expected error in long-term recall.

Our findings suggest that communication among opinion leaders, early adopters and other dentists may be increasing the adoption of fluoride varnish use. Peer-to-peer education appears to distinguish early from later adopters of fluoride varnish use, with early adopters reporting greater involvement with other dentist friends and acquaintances who use dental procedures included in the medical model, and reporting, as well, that they seek advice from and provide it to these colleagues. This finding is consistent with Rogers’⁵ diffusion theory.

Recent studies of physicians concluded that educating key physicians to whom colleagues turn for advice can improve medical care and play an important role in introducing physicians to new treatment standards. In one such study, physicians who were respected in their communities for their medical opinions, but not necessarily leaders in the medical establishment, were identified and given specialized training about new treatment guidelines for patients who had had heart attacks. This resulted in an increase in the use of beneficial new treatments.¹⁷ Similar studies using this methodology among dental-practice opinion leaders involving the medical model may be feasible, and they ultimately may promote adoption of caries control services—particularly use of fluoride varnish.

	CONCLUSION

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In January 1996, WDS added fluoride varnish as a covered benefit. Two years later, the use of fluoride varnish by general dentists increased from 32 to 44 percent. The increase in use may be due to reimbursement, as well as other factors. Given evidence that fluoride varnish is effective in preventing caries, the technology remains underutilized.