However, not all Americans have adequate access to dental care,⁵ and not all those who have dental insurance seek regular dental care.⁶ Significant disparities exist in the utilization of dental care services among population groups. For example, men and older adults are less likely to visit a dentist than are women and younger adults,^5,7 and people from minority populations or with low socioeconomic status visit dentists less frequently than do others.^7,8

The Healthy People 2010 objectives call for an increase in the proportion of people who seek regular dental care annually to 56 percent by 2010 (a 12-percentage-point increase from 44 percent in 1996).⁹ To increase regular dental visits among various population groups, we need to identify the modifiable factors that influence regular dental visits. The demand for dental care is affected by economic and sociodemographic factors, dental insurance status, perceived need for care and the relative priority placed on oral health.

Population-based studies have identified barriers to regular dental visits, including lack of dental insurance, lack of usual source of care and fear of dental visits.^2,10,11 Although researchers have reported the association between each of these factors and regular dental visits among various populations (after accounting for other contributing factors), few studies have reported how these factors interact to influence regular dental visit behaviors. The objective of this study was to investigate the impact of dental anxiety and other determinants, such as dental insurance and income, on regular dental visits in a representative adult dentate population in the Detroit tri-county area (Wayne, Macomb and Oakland counties).

To determine a respondent’s dental anxiety level, the authors used a four-item dental anxiety scale.

	SUBJECTS, MATERIALS AND METHODS

TOP ABSTRACT SUBJECTS, MATERIALS AND METHODS RESULTS DISCUSSION CONCLUSION REFERENCES

 
The data used in this analysis were collected as part of a study of the preferences for treatment outcomes for teeth with irreversible pulpitis. Study details can be found elsewhere.¹² This study was a cross-sectional survey carried out between August 2000 and August 2001, that used a sample of adults representing a population of 3 million residents in the Detroit tricounty area. For this analysis, we used data collected from a self-administered questionnaire that was mailed to respondents and checked at the respondents’ homes for completeness by trained interviewers before they conducted face-to-face interviews. The Health Sciences Institutional Review Board of the University of Michigan, Ann Arbor, reviewed and approved the study design and methods, including participant recruitment, telephone and face-to-face interviews and the survey questionnaire, as well as the informed consent form.

Sampling and recruitment process. We used a random-digit dialing method to select a representative sample.¹³ We selected a random sample of 2,372 numbers from randomly generated telephone numbers in the Detroit tricounty area. Trained interviewers at the Institute for Social Research, University of Michigan, carried out the telephone screening using the computer-assisted telephone interviewing (CATI) system.

Telephone screening began with identifying whether the number belonged to a household in the Detroit tricounty area. The interviewers administered a short screening questionnaire to determine eligibility and dental insurance coverage of each individual in the household. Eligibility criteria were as follows: an adult aged 18 through 69 years, currently living in the household and having at least one natural tooth in his or her mouth.

During a screening telephone call, the interviewer categorized a household as "noninsured" if at least one adult between the ages of 18 and 69 years did not have dental insurance. They categorized households as insured if the respondent reported that all adults in the household were covered by a dental insurance plan (not including Medicaid). All nonin sured households identified during the screening were invited to partic ipate in the study. For all households in which all adults had dental insurance, the CATI system randomly selected one-half of such households to participate. Once a household was selected to participate, all eligible adults in the household were invited to participate in the study.

Questionnaire. We developed a questionnaire to collect information about regular dental visit behaviors, dental anxiety level, self-perceived oral health status, dental insurance status, and experience with dental treatment and dental pain, as well as to collect sociodemographic information. Specifically, we determined regular dental visit behavior by asking, "Do you visit a dentist regularly for dental care?" We measured self-perceived oral health status by asking respondents, "How would you describe the condition of your mouth and teeth (excellent, very good, good, fair or poor)?"

To determine a respondent’s dental anxiety level, we used a four-item dental anxiety scale (DAS), which is based on Corah’s DAS^14,15 and the revised DAS¹⁶ (Box). Each item on the DAS has multiple choices, with scores ranging from 1 (most relaxed) to 5 (most anxious); therefore, a total DAS score can range between 4 and 20. In our analysis, we defined a respondent as being dentally anxious if he or she scored 13 or higher on the DAS, as recommended by Corah and colleagues.¹⁵ We pretested the questionnaire for reliability with 40 adult volunteers. The internal consistency of the four questions on the DAS in the questionnaire was 0.88, indicating that all items measured the same phenomenon: dental anxiety.

View this table: [in this window] [in a new window]   BOX DENTAL ANXIETY SCALE.*

We used survey data analysis software (SUDAAN, Release 7.5) to estimate variances adjusted for correlations (that is, not being independent) among people within a household, because the sampling unit in this study was a household rather than individuals.¹⁷ The statistical analysis included a descriptive analysis and a bivariate analysis of crude relationships between regular dental visit behavior and factors such as dental insurance status, dental anxiety score and demographic factors, including age, sex, race/ethnicity, annual household income and educational level.

We constructed multiple logistic regression models to investigate the effect of each variable on regular dental visit behavior after accounting for other contributing factors. The logistic regression model included all sociodemographic factors. Other factors were added if they were found to be statistically significant at the 0.1 level. We tested plausible interactions in the regression model. Of interest were the interactions among dental insurance status, education, race, income, sex and dental anxiety level.

	RESULTS

TOP ABSTRACT SUBJECTS, MATERIALS AND METHODS RESULTS DISCUSSION CONCLUSION REFERENCES

 
From the 1,569 telephone numbers identified as residential, we screened 925 households (59 percent) to determine their eligibility and the household’s dental insurance status. The screeners identified 621 of these 925 as households in which all adults had dental insurance. Of these 621, 314 were chosen randomly to participate in the study. Two hundred nine (67 percent) of these 314 households agreed to participate. The remaining 304 households had at least one adult without dental insurance, and we invited all of them to participate in the study; 237 (78 percent) agreed to do so.

We invited all eligible adults from these 446 households to participate in the study, which resulted in a sample of 807 people. Of these, 630 people (78 percent) who resided in 368 households actually completed the interviews and questionnaires.

Table 1 presents the sociodemographic characteristics of adults who participated in this study. For dental health–related characteristics, about 72 percent of adults answered that they had dental insurance (excluding Medicaid). About 63 percent answered that they visited a dentist regularly; about 12 percent reported that they had high dental anxiety; and about 69 percent responded that they had good-to-excellent oral health.

View larger version (40K): [in this window] [in a new window]   Figure 1. Treatment received and reasons for dental visits during the previous year. Asterisk indicates P < .01. Dagger indicates P < .1.

Self-perceived oral health status was significantly associated with having had regular dental visits. Respondents who reported having good-to-excellent oral health were more likely to visit dentists regularly than were those who reported having fair-to-poor perceived oral health. However, we could not determine whether regular dental visits improved self-perception of oral health or vice versa based on the data collected in this cross-sectional survey (Table 2).

In the logistic regression model, the variability of regular dental visits was explained—in descending order of magnitude—mainly by perceived oral health status, sex, dental insurance status and dental anxiety level. Age, race and annual household income also remained significant determinants in the model. This model explained 36 percent of the variability in regular dental visits among the respondents (Table 3, page 64). Educational level, which exhibited a significant association in the bivariate analysis, became insignificant after controlling for other variables. Therefore, we excluded educational level from the final model.

View larger version (54K): [in this window] [in a new window]   Figure 2. Regular dental visits and dental anxiety status by dental insurance status. Asterisk indicates the odds of having a dental visit. Odds ratios were adjusted for the same variables as in Table 2 in a logistic regression model with the interaction term. The P value of the interaction term (Wald statistic) was .029, and R2 of the model was .364. Dagger indicates a score of 13 or higher on Corah’s Dental Anxiety Scale (modified).14,16

	DISCUSSION

TOP ABSTRACT SUBJECTS, MATERIALS AND METHODS RESULTS DISCUSSION CONCLUSION REFERENCES

Several studies have measured the behaviors of regular dental visits or preventive dental visits in several ways.^10,18,20,22 In our study, we measured the regularity with which respondents sought dental care by asking, "Do you visit a dentist regularly for dental care?" Answers to this question, when cross-compared with answers to questions about the reasons for dental visits, indicated that those who answered that they visit dentists regularly were more likely to receive preventive dental care than problem-oriented care.

A unique finding of this study is a disproportionate association between regular dental visits and dental anxiety level among those with and without dental insurance. Logistic regression models show that the influence of dental insurance on regular dental visits is modified significantly by the presence of dental anxiety. The U.S. Department of Health and Human Services²³ reported that people with dental insurance visited their dentists more regularly than did those without dental insurance. However, previous studies have found that about one in three people with private dental insurance did not seek regular dental care.^6,8 Findings from our study on the interaction between dental anxiety and dental insurance status provide an insight—at least in part—regarding why some people do not seek dental care regularly despite the fact that they have private dental insurance.

This study was not designed to explain why the effect of dental anxiety was prominent only among those who had dental insurance. It seems that among the uninsured, dental anxiety may not influence regular dental visits because the expectation is that dentists are to be visited only when there is an urgent oral health problem. Among the insured, however, anxiety is a factor because the expectation is that regular dental visits are part of the "free" care provided under an employment-based insurance plan.

In the 1990s, dental professionals and others paid significant attention to increasing access to dental care.²⁴ While it is essential to increase access to dental care to promote oral health and treat dental and oral diseases, providing dental insurance alone might not be enough to eliminate disparities in oral health.²⁵ Findings from this study underscore the importance of removing other barriers, such as dental anxiety, along with providing dental insurance coverage.

Doerr and colleagues²⁶ reported that factors such as being female, having a low income and having a low perception of one’s oral health status are associated with higher dental anxiety. Researchers also have reported that traumatic dental experiences during childhood,²⁷ family influences,²⁷ certain psychological conditions²⁸ and a high general fear level²⁹ were associated with the onset of dental anxiety. A number of methods can be used to alleviate dental anxiety in dental offices, including the use of medication³⁰ and cognitive modification.³¹ However, little information is available regarding the efficacy of dental anxiety treatments on increasing dental visits.^32,33 We need to train practitioners in the causes and treatment of dental anxiety.

Study limitations. Because we used a cross-sectional survey to collect the data for this study, associations between the regularity of dental visits and the factors considered do not provide information on causality. In addition, as with any study involving a self-administered questionnaire (compared with more objective measures such as auditing dental records or reviewing an insurance claims database), this study was prone to over-reporting of frequency or regularity of dental visits and reporting socially desirable answers with regard to respondents’ reasons for dental visits.

The sampling used in this study is based on a random-digit-dialing method, which has been demonstrated to result in representative samples.³⁴ One major drawback associated with this method, however, is the lack of coverage of people who do not have telephones. The Federal Communications Commission³⁵ reported that fewer than 5 percent of households in Michigan do not have a telephone. To be precise, then, the findings of this study represent people living in the Detroit tricounty area with home telephones.

	CONCLUSION

TOP ABSTRACT SUBJECTS, MATERIALS AND METHODS RESULTS DISCUSSION CONCLUSION REFERENCES

 
Our study results indicate that self-perceived oral health status, dental insurance status and dental anxiety influence regular dental visits among dentate adults. Dental anxiety is a significant determinant of whether people will make regular dental visits, especially among people who have private dental insurance. The dental profession and government officials should consider these factors when planning programs to enhance access to dental care services, as well as when developing training programs for dental professionals.