The supply of dental services is frequently associated

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1 Economic Impact of Dental Hygienists on Solo Dental Practices Vickie F. Lazar, M.A., M.S.; Albert H. Guay, D.M.D.; Tryfon J. Beazoglou, Ph.D. Abstract: The fact that a significant percentage of dentists employ dental hygienists raises an important question: Are dental practices that utilize a dental hygienist structurally and operationally different from practices that do not? This article explores differences among dental practices that operate with and without dental hygienists. Using data from the American Dental Association s 2003 Survey of Dental Practice, a random sample survey of U.S. dentists, descriptive statistics were used to compare selected characteristics of solo general practitioners with and without dental hygienists. Multivariate regression analysis was used to estimate the effect of dental hygienists on the gross billings and net incomes of solo general practitioners. Differences in practice characteristics such as hours spent in the practice and hours spent treating patients, wait time for a recall visit, number of operatories, square feet of office space, net income, and gross billings were found between solo general practitioners who had dental hygienists and those who did not. Solo general practitioners with dental hygienists had higher gross billings. Higher gross billings would be expected, as would higher expenses. However, net incomes of those with dental hygienists were also higher. In contrast, the mean waiting time for a recall visit was higher among dentists who employed dental hygienists. Depending on personal preferences, availability of qualified personnel, etc., dentists who do not employ dental hygienists but have been contemplating that path may want to further research the benefits and opportunities that may be realized. Ms. Lazar is Manager, Health Policy Resources Center, American Dental Association; Dr. Guay is Chief Policy Advisor, American Dental Association; and Dr. Beazoglou is Professor, Department of Craniofacial Sciences, School of Dental Medicine, University of Connecticut Health Center. Direct correspondence and requests for reprints to Ms. Vickie Lazar, American Dental Association, 211 East Chicago Avenue, Chicago, IL 60611; lazarv@ada.org. Keywords: dental health care delivery, dental hygiene practice, dental hygienists, economics of dentistry, solo general dental practice, practice management The supply of dental services is frequently associated primarily with time spent by a dentist producing dental services. It goes without saying that the dentist s time is critical to the production of many dental services. Studies have also shown, however, that allied dental personnel, equipment, and supplies are important determinants of dental practice productivity, marketability, and value. 1-3 Beazoglou et al. found that a 10 percent increase in dental hygienist hours would increase dental output per hour (measured by dentist annual gross billings) by 2.74 percent. 1 Levin reported that effective and efficient use of dental hygienists can lead to the equivalent of more than 50 percent of a dentist s production. 2 Throughout the United States, there are dental practices that employ dental hygienists and those that do not. The annual surveys of dental practice conducted by the American Dental Association (ADA) have consistently found that the majority of dentists employ dental hygienists. 4 The fact that a significant percentage of dentists employ dental hygienists raises an important question: Are dental practices with a dental hygienist structurally and operationally different from practices without a hygienist? Some differences are obvious: the employment of dental hygienists increases the number of allied dental personnel and total expenses of a practice, and hygienists spend more time on cleanings, give more detailed hygiene instruction, and free the dentist to perform other procedures. However, it is not clear whether the presence or absence of a hygienist affects the hours worked by the dentist, the number of patient visits, waiting time for an appointment, office size, patient characteristics, and equipment use. A more fundamental question is this: Does the employment of dental hygienists affect gross billings or net income of a dental practice? The purpose of this article is twofold: 1) to compare selected characteristics of solo general practitioners with and without dental hygienists, and 2) to estimate the effect of hygienists on gross billings and net income of solo general practitioners. Methodology The main source of data utilized in this study was the 2003 Survey of Dental Practice (SDP). 5 The SDP, conducted by the Survey Center of the ADA, collects the most comprehensive and reliable information on various practice characteristics such as work schedules, patient visits, patient characteristics, non-dentist staff employment, expenses, income, and wages. August 2012 Journal of Dental Education 1045

2 Dentists were asked to provide selected, aggregate (i.e., percentages) information on age, gender, race/ethnicity, and insurance coverage of their patient base. Thus, the numbers discussed here are not selfreported by patients. The majority of the patients of both groups of dentists were covered by a private insurance program that paid or partially paid for their dental services. In addition, dentists were asked to indicate whether any of twenty-one equipment items were utilized in their practices. Finally, the 2003 SDP included a question on current fees charged for thirteen commonly performed dental procedures, four of which are associated with dental hygienists. The SDP is sent to a randomly selected group of dentists in private practice, including general practitioners and specialists, ADA members and nonmembers. Every three years, a long form of the survey is used in which additional questions are asked (e.g., fees, equipment use, etc.). The 2003 SDP (relating data for 2002) is the most recent long-form questionnaire available with equipment use and fee questions in one questionnaire. The data collection for this survey began in May 2003 with a mailing to 7,992 dentists in private practice. 5 Two follow-up mailings were sent to nonrespondents. After the three mailings, nonrespondents were contacted by telephone. Data collection was completed in December The sample was adjusted by removing dentists who were retired, deceased, not in private practice, or not locatable, resulting in a final adjusted overall response rate of 33.4 percent. 5 For this study, the analysis was limited to the following cohort of respondents: 1) dentists whose primary occupation was private practice (full-time or part-time); 2) dentists who had been in their current practice for at least one year; and 3) solo general practitioners. The selection process resulted in a cohort of 854 solo general practitioners. All data analyses were conducted using the statistical software package SAS 9.1. The characteristics of those who employed dental hygienists were compared with those who did not employ dental hygienists through the use of descriptive analysis. The data allowed for an assessment of differences in frequencies and means between dentists with and without hygienists, using t-tests for measuring statistically significant differences. The specific characteristics of solo general practitioners that were used for the descriptive analysis are listed in the tables. It should be noted that the number of observations in each comparison is not constant as the number of respondents to each question in the 2003 SDP varied. To assess the effect of a dental hygienist on the gross billings and net income of a solo general practitioner, multivariate regression analysis was performed. 6 Both gross billings and net income from the primary private practice were used as dependent variables. In both equations, the explanatory variable of interest was the presence (or absence) of a dental hygienist. A dummy variable ( Hyg ) was constructed to represent whether there was a dental hygienist in the practice. A value of zero was assigned to the variable Hyg if there were no dental hygienists in the dental practice, and a value of one if there were one or more dental hygienists in the practice. A host of control variables were used to account for other influences on gross billings or net income including number of patient visits, age of dentist, office size, time spent treating patients, patient characteristics (insurance coverage, age, race/ethnicity, and gender), region of the country where the practice was located, years of experience of the dentist, and fees charged for specific procedures. The estimated coefficient for the variable Hyg would indicate the contribution to the gross billings or net income of a practice, holding all other variables in the regression constant. Results Sample Characteristics The mean age among the 854 solo general dentists was 51.5 years. Dentists with dental hygienists were about 2.9 years younger than their peers without dental hygienists (50.4 and 53.3 years of age, respectively). Of these 854 practitioners, 91.5 percent were male, and 8.5 percent were female. The majority (60.6 percent) employed one or more dental hygienists; 39.4 percent did not employ a hygienist. The mean number of hygienists among dentists employing dental hygienists was 1.8, and the mean number of visits per week treated by all hygienists in these practices was Defining full-time dentists as those who work thirty or more hours per week and forty-eight or more weeks per year ( 1,440 hours per year) and part-time dentists as those who work fewer than 1,440 hours per year resulted in a classification of 86 percent as full-time and 14 percent as part-time. Among full-time solo general practitioners, 36.6 percent did not have dental hygienists, compared to 51.7 percent among part-timers Journal of Dental Education Volume 76, Number 8

3 The mean number of weeks per year worked by this cohort of dentists was On average, 36.2 hours per week were spent in the office, of which 33.1 hours were spent treating patients. Total patient visits per week averaged 47.5 visits. The mean number of operatories and square feet of space were 3.5 and 1,549.9, respectively. Solo dental practices employed on average 1.6 chairside assistants and 1.8 other staff. Mean net income from the primary practice was $165,085; mean gross billings were $497,700; and mean practice expenses of operating the practice were $307,218, exclusive of the dentist labor costs. Descriptive Analysis Practice characteristics. Table 1 compares selected practice characteristics of solo general practitioners based upon whether they employed dental hygienists. Solo general practitioners who employed dental hygienists spent about 1.1 hours more per week in the practice (p=0.0159) and 1.1 hours more per week treating patients in the office (p=0.0386). In contrast, there was little or no difference between the two groups of dentists with regards to the number of weeks worked per year (p=0.2701), the number of non-hygienist dental visits per week (p=0.7272), and the mean number of visits per patient per year (p=0.7159). Regarding patient visits initiated by the dentist s office (i.e., a recall visit), the mean wait time (measured in days) for a recall visit was longer (p=0.0075) for dentists with dental hygienists than those without dental hygienists (15.2 versus 9.1 days). The shorter wait time for an appointment among dentists without dental hygienists would be attractive to patients because they can see the dentist more quickly if required. However, for the dentist, it could suggest that their appointment schedules are less busy than their colleagues who do have dental hygienists. Practitioners with dental hygienists had more operatories (mean difference=1.3; p<0.0001), chairside assistants and other staff (mean difference=0.6; p<0.0001), and square feet of office space (mean difference=461.0; p<0.0001) (Table 1). These findings makes sense: a dentist with a dental hygienist would be more likely to have more space and operatories as the dental hygienist and the dentist require a similar amount of space and equipment to provide care. Patient characteristics. Solo general practitioners who employed hygienists reported that 65.2 percent of their patients had private dental insurance (Table 2) 5.8 percentage points higher than dentists Table 1. Practice characteristics among solo general practitioners with and without dental hygienists, 2002 All No Dental Hygienists One or More Dental Hygienists Number of Respondents p-value Deviation Number of Respondents Mean Deviation Mean Number of weeks worked Hours per week spent in practice Hours per week treating patients Number of times a typical patient visited the practice Dentist patient visits per week (excluding hygienist visits only) Wait for recall visit (days) Number of operatories < Square feet of office space < Chairside assistants < Other staff < In solo general practices, the mean number of hygienists was 1.8, and the standard deviation was 1.0. August 2012 Journal of Dental Education 1047

4 without dental hygienists (p=0.0007). In contrast, those without dental hygienists reported that 11.9 percent of their patients were covered by a public assistance program that paid or partially paid for their dental care compared to 3.3 percent of the dentists who had one or more dental hygienists (p<0.0001). There was no statistical difference regarding patients not covered by insurance (p=0.1104). Also, there was no difference regarding the age and gender of patients between the two groups of dentists (all p- values exceeded 0.5). The percentage distribution of Hispanic or Latino patients and Asian patients was higher among dentists without dental hygienists (p< for both) (Table 2). In contrast, the percentage distribution of white patients was higher among dentists with dental hygienists (p=0.0075). There were no other differences for patients races. Equipment use. The percentage utilization of fourteen of the twenty-one dental equipment items was significantly higher (p<0.05) among dentists with a dental hygienist than those with no dental hygienist (Table 3). (In the table, the list of equipment is displayed in descending order of the absolute value of the percentage point differences.) For only two dental equipment items silver recovery unit and amalgam separator the percentage use was higher among those without dental hygienists, although the differences were not statistically significant (p= and p=0.2296, respectively). The differences in percentage utilization distributions among the two groups of dentists were not statistically significant for the other nine pieces of equipment. There was over a 25 percentage point difference in favor of those practices with dental hygienists for the following four equipment items: panoramic x-ray unit (p<0.0001), nitrous oxide analgesic equipment (p<0.0001), scavenger system for nitrous oxide (p<0.0001), and intraoral video camera (p<0.0001). For instance, 31.8 percent of solo general practitioners who did not employ dental hygienists indicated utilizing a panoramic x-ray unit compared to 63.0 percent of the dentists who did employ dental hygienists a difference of 31.2 percentage points. Fees, net income, gross billings, and practice expenses. Tables 4 and 5 compare fees, net income, gross billings, and practice expenses of solo general practitioners with and without a hygienist. Fees for dental procedures, as with prices of any purchasable items, are based upon the individual seller s (or firm s) considerations as well as market considerations. There was no difference between what solo general practitioners with dental hygienists and those without dental hygienists charged for adult prophylaxes and topical application of fluoride (p= and p=0.5175, respectively). Dentists with hygienists charged about $2.69 more for bitewings four films compared to the dentists who did not have dental hygienists (p=0.0143). For periodontal scaling and root planing per quadrant, dentists who did not employ dental hygienists charged about $20.78 less than those who did have dental hygienists (p<0.0001). Table 5 shows the mean net income, gross billings, and practice expenses for the two groups of dentists. The average for each variable is the average of only those who answered the question; not every respondent answered all three questions. Therefore, in this table, subtracting expenses from billings will not equal net income. The differences in net income, gross billings, and practice expenses between solo general practitioners with and without hygienists were statistically significant (p< for all three variables). The differences were also practically significant: annual net income was about $56,102 (31 percent) greater in those solo practices that did have dental hygienists, and their annual gross billings balance was about $231,134 (41 percent) greater. As expected, practice expenses of those employing dental hygienists were higher than those practices without dental hygienists. Multivariate Analysis Results Tables 6 and 7 show the results of the regression analyses. The R-squared measures ( and ) in the net income and gross billings regressions, respectively, were significant. The R-squared statistics indicate that the included independent variables explain about 27 percent and 41 percent of the variance in net income and gross billings. Table 6 shows the results of the regression for net income. The presence of a dental hygienist ( Hyg ) is statistically significant (p<0.0001) and has a positive value of $58,290. Thus, hygienists were a significant predictor of greater net income, even after adjusting for other factors that influence net income, such as age of dentist, patient load, office size, time spent treating patients, and experience. Table 7 shows the results of the regression for gross billings. The coefficient of the dummy variable indicating the presence of a dental hygienist ( Hyg ) is statistically significant (p<0.0001) and has a positive value of $237,567. Solo practices employing dental hygienists generate much more gross income Journal of Dental Education Volume 76, Number 8

5 Table 2. Mean percentage distribution of patients, by various characteristics, among solo general practitioners with and without dental hygienists, 2002 Mean All No Dental Hygienists One or More Dental Hygienists Deviation Number of Respondents Mean Deviation Number of Respondents p-value Insurance Coverage Age Private insurance 63.7% 18.7% % 22.9% % 16.8% Public assistance 5.5% 13.3% % 20.8% % 8.4% 453 <.0001 No insurance 30.8% 17.6% % 20.0% % 16.7% years and younger 14.6% 9.2% % 11.4% % 8.4% to 39 years 28.3% 10.8% % 11.6% % 10.5% to 64 years 36.4% 12.3% % 13.8% % 11.8% years and older 20.7% 11.9% % 13.4% % 11.3% Gender Male 44.0% 7.4% % 7.9% % 7.1% Female 56.0% 7.4% % 7.9% % 7.1% Race/Ethnicity Hispanic or Latino 9.5% 15.0% % 24.7% % 8.6% 412 <.0001 White 82.0% 20.6% % 28.3% % 17.8% Black or African-American 9.5% 13.9% % 18.1% % 12.7% American Indian or Alaska Native 1.1% 2.9% % 2.2% % 3.1% Asian 5.4% 13.3% % 22.7% % 9.0% 272 <.0001 Native Hawaiian or Pacific Islander 0.9% 2.9% % 3.5% % 2.7% Other 1.6% 5.8% % 3.5% % 6.3% August 2012 Journal of Dental Education 1049

6 Table 3. Percentage distribution of equipment utilization among solo general practitioners with and without dental hygienists, 2002 No One or More Percentage Dental Dental Difference All Hygienists Hygienists (with minus (N=685) (N=179) (N=506) without) p-value Intraoral video camera 42.3% 18.4% 50.8% 32.4% < Panoramic x-ray unit 54.9% 31.8% 63.0% 31.2% < Nitrous oxide analgesic equipment 55.9% 35.8% 63.0% 27.2% < Scavenger system for nitrous oxide 48.0% 28.5% 55.0% 26.5% < Automatic x-ray film processor 81.6% 66.5% 87.0% 20.5% < High-speed air handpiece 73.9% 61.5% 78.3% 16.8% < Electrosurgical unit 46.9% 34.6% 51.2% 16.6% Ultrasonic or sonic scaling unit 94.0% 82.1% 98.2% 16.1% < Professional bleaching products 93.3% 82.7% 97.0% 14.3% < Oral cancer detection brush 34.3% 26.8% 37.0% 10.2% Digital x-ray unit 13.6% 6.2% 16.2% 10.0% Modular instrument delivery system 23.1% 17.3% 25.2% 7.9% Biological indicator 72.8% 67.6% 74.7% 7.1% Dental unit waterlines cleaning devices 52.3% 47.8% 53.9% 6.1% Surgical laser 4.1% 1.1% 5.1% 4.0% Amalgam separator 23.5% 26.8% 22.4% -4.4% Sterilizable handpiece 97.7% 95.5% 98.4% 2.9% Silver recovery unit 25.7% 27.4% 25.1% -2.3% Dental laser for bleaching or whitening 7.2% 5.6% 7.7% 2.1% Composite light curing unit 99.0% 97.8% 99.4% 1.6% Dental laser for restoring teeth 2.9% 2.2% 3.2% 1.0% Discussion In 2002, the majority of general dentists in private practice (63.4 percent) were solo practitioners. Based on the 2003 SDP, almost 40 percent of the solo dentists employed no dental hygienists. This seems to be a high percentage of practices, given improvements in oral health and the shift towards preventive services. Interestingly, solo dentists with and without dental hygienists differ in mean age by less than three years; those with hygienists are younger. There were other significant differences in the structural and operational characteristics between solo general practices with and without dental hygienists. Specifically, solo general practices with hygienists used more operatories, office space, chair-side assistants, and other staff. In addition, solo general dentists with hygienists were more likely to have invested in more of the specified equipment items than solo general dentists without hygienists. Furthermore, there were differences in patient characteristics between solo dentists with and without hygienists. Perhaps of most interest, those solo practices without hygienists saw a higher percentage of Med- icaid patients, while those practices with hygienists saw a higher percentage of private insurance patients. The percentages were not large but were statistically significant, indicating that practices without dental hygienists saw slightly more disadvantaged patients. Finally, there were differences in some fees but not others between the two sets of practices. Differences in the average fees for prophylaxes and application of topical fluoride were not observed between the two types of practices. This finding is somewhat surprising, considering that these are two procedures that dental hygienists routinely provide when present but dentists have to provide if they do not employ dental hygienists. The data suggest that the dentists in this study did not charge a premium for providing those services that dental hygienists usually provide. Modest differences in average fees were observed between the two types of practices for taking bitewings and performing scaling and root planing. Dental hygienists do perform both of those procedures in many practices. However, bitewings are more frequently taken by other staff, and dentists frequently provide scaling and root planing themselves, even if dental hygienists are on staff Journal of Dental Education Volume 76, Number 8

7 Table 4. Mean fees (in dollars) for selected procedures among solo general practitioners with and without dental hygienists, 2002 Mean All No Dental Hygienists One or More Dental Hygienists Deviation N p-value Bitewings four films (D0274) Prophylaxis adult (D1110) Topical application of fluoride (including prophylaxis) child (D1201) Periodontal scaling and root planing < per quadrant (D4341) N=number of respondents + Disclaimer: The fee data displayed in this table should not be interpreted as constituting a fee schedule in any way and should not be used for that purpose. Dentists must establish their own fees based on their individual practice and market considerations. The American Dental Association discourages dentists from engaging in any unlawful concerted activity regarding fees or otherwise. Table 5. Mean net income, gross billings, and practice expenses among solo general practitioners with and without dental hygienists, 2002 Mean All No Dental Hygienists One or More Dental Hygienists Deviation N p-value Net income (after practice expenses and business taxes) from the primary practice $165,085 $104, $126,888 $95, $182,990 $104, < Practice gross billings $497,700 $270, $337,003 $252, $568,137 $248, < Total practice expenses $307,218 $206, $172,488 $135, $365,987 $205, < N=number of respondents August 2012 Journal of Dental Education 1051

8 Over the past twenty years, dental practices have included more support staff, equipment, operatories, and office space. 7 However, products and equipment purchased by the dental practice are purchases in a national marketplace so that there are no differences in prices among dental practices. In contrast, there are perhaps local differences in the wage rates of hygienists, dental assistants, and other office staff that could affect the supply of services. Dental hygienists are an integral part of many dental practices throughout the United States. However, the decision of dentists to employ or not to employ dental hygienists is not at question here. As in any industry, the decision of employment of personnel is complicated and dependent on many variables such as the economy, local market conditions, resources, personal preferences, and availability of competent personnel. For instance, according to a 1999 survey conducted by International Communications Research, 8 two out of three private practitioners (65.8 percent) felt there was not an adequate supply of dental hygienists in their area. There was a lot of variation among responding dentists by region and state. Dentists who perceived inadequacies in the supply of allied dental staff reported that such shortages have financial implications as well as negative impact on patient care. 8 The evidence presented in this article shows that the gross and net incomes of solo general practices with dental hygienists were significantly higher than those without hygienists even after controlling for other explanatory variables. Of course, these higher incomes reflect not only the presence of dental hygienists but the additional investment in equipment, risk taking, and management of a larger dental practice. Is this difference in net income sufficient compensation for a general dentist to establish and operate a solo general practice with dental hygienists? Apparently, 60 percent of solo general dentists believe the compensation is sufficient, while the other 40 percent believe it is not sufficient or are not aware of the financial advantages that dental hygienists provide practices when they are present. An issue that cannot be addressed with this study s data is the reasons that some 40 percent of solo general practitioners do not employ dental Table 6. Regression analysis of independent predictors of net income for solo general practitioners, 2002 Independent Variable Parameter Estimate t-value Pr> t 95% Confidence Interval Intercept Years of experience Age Age of dentist squared Hours per year treating patients Presence of a dental hygienist ( Hyg ) < Number of patients treated per year < Square feet of office space < N=352 F=18.56; Probability F< R-square=0.2742; Adj R-square= Table 7. Regression analysis of independent predictors of gross billings for solo general practitioners, 2002 Independent Variable Parameter Estimate t-value Pr> t 95% Confidence Interval Intercept Years of experience Age Age of dentist squared Hours per year treating patients Presence of a dental hygienist ( Hyg ) < Number of patients treated per year < Square feet of office space < N=378 F=37.01; Probability F< R-square=0.4118; Adj R-square= Journal of Dental Education Volume 76, Number 8

9 hygienists. At least three non-mutually exclusive explanations are possible. First, some dentists may not have adequate patient demand to justify full- or part-time hygienists. The argument against this explanation is that, with comparable numbers of patient visits, the demand for dental hygienists should be similar for the two groups of dentists. A second possibility is the preferred lifestyle of dentists. Some may not want the managerial responsibilities associated with a larger staff. Likewise, some may enjoy providing hygiene services. Finally, dental hygienists may actually increase patient demand beyond the capacity of the dentist to provide all other non-hygiene patient services. The recent article by Pourat 9 provides some evidence to support all these explanations. Clearly, this is an important issue that requires further study. Conclusions The purpose of this study was to empirically compare and contrast solo general dental practices with and without dental hygienists. The findings indicate that there are significant structural and operational differences between the types of solo general practices. The study demonstrates that there are benefits in the gross billings and net income from having dental hygienists in solo practices. It seems that the majority of solo general dentists find that the benefits exceed any disadvantages that may be present. The recruitment, hiring, and retention of highquality staff are an investment in the practice. 10 Dental hygienists (along with dental assistants) are primary allied dental professionals with clinical patient contact. They are extremely valuable to dentists because they help expand dentists service capacity by performing tasks delegated by dentists. Specifically, dental hygienists focus on oral health promotion and disease prevention renders them an essential team member of current and future dental practices. 10 There are numerous variables involved in running and maintaining a successful dental practice (mix of procedures, number of patients, number of staff, etc.). Each dentist must assess the pros and cons of all applicable variables and determine the optimum practice plan for himself or herself. However, this study strongly supports the finding that dental hygienists are a good investment in that dentists who do employ dental hygienists have greater production and larger gross and net incomes. Acknowledgment The authors would like to thank Howard L. Bailit, D.M.D., Ph.D., for his review of this article and his immensely valuable comments and suggestions. REFERENCES 1. Beazoglou T, Heffley D, Bailit H, Brown LJ. The importance of productivity in estimating need for dentists. J Am Dent Assoc 2002;133(10): Levin RP. Increasing hygiene productivity. Compend Contin Educ Dent 2003;24(3): Adams W. Dental hygiene s influence on the marketability and value of dental practice. Dent Today 2003;22(9): American Dental Association Survey Center. Survey of dental practice. Chicago: American Dental Association, various years. 5. American Dental Association Survey Center survey of dental practice: database. Chicago: American Dental Association, Stevens J. Applied multivariate statistics for the social sciences. 3rd ed. Mahwah, NJ: Lawrence Erlbaum Associates, Brown LJ. The adequacy of current and future dental workforce: theory and analysis. Chicago: American Dental Association, Health Policy Resources Center, International Communications Research. Dental health policy analysis series: 1999 workforce needs assessment survey. Rev. ed. Chicago: American Dental Association, Pourat N. Differences in characteristics of California dentists who employ dental hygienists and those who do not. J Am Dent Assoc 2009;140(8): Ohrn K. The role of dental hygienists in oral health prevention. Oral Health Prev Dent 2004;2(Suppl 1): August 2012 Journal of Dental Education 1053