Oral health knowledge and oral health related quality of life of older adults

Abstract Objective To assess the relationship between oral health knowledge and oral health related quality of life among older adults with different ethnicities living in San Bernardino County, California. There is a gap in oral health knowledge (OHK) and how it relates to perceived oral health related quality of life. Thus, there is a need to assess OHK as a component of oral health literacy and identify areas in which knowledge gaps exit to develop educational strategies that address the need of the elderly population. Materials and Methods The study was a cross‐sectional study that included adults 65 years and older using a validated “Comprehensive Measure of Oral Health Knowledge” (CMOHK) and an “Oral Health Profile Index” (OHIP‐14). Odds ratios were conducted to determine the factors associated with OHK. Results Mean OHK score were 16.8, 14.6, and 8.9 for Caucasian, Asian, and Hispanics, respectively. “Poor” OHK was significantly associated with participants over the age of 75 years (OR = 1.9; 95% CI: 1.15–3.16), high school education or less (OR = 10.8; 95% CI: 5.92–19.84), minority ethnicity (OR = 7.3; 95% CI: 4.27–12.61), income less than $25,000 (OR = 10.7; 95% CI: 5.92–19.26), and reading ability less than “Excellent” (OR = 7.27; 95% CI: 4.35–12.14). Mean OHIP‐Severity scores were 7.4, 12.5, and 24.4 for Caucasian, Asian, and Hispanics, respectively. Respondents with Poor OHK were 5.17 times more likely to be identified with high levels of severity (Severity >10). Conclusion It is imperative to develop communication strategies to inform older adults on oral health knowledge that provide equal opportunities for all ethnicities.


| INTRODUCTION
Every day 10,000 Americans turn 65 years of age and by 2030, one out of five Americans will be over the age of 65 (Federal Interagency Forum on Aging-Related Statistics, 2012). Dental and scientific advances offer new innovations for the improvement of oral health for our society. Yet a disproportionate burden of poor oral health continues among many underserved minority groups and elderly people (Lazarchik & Haywood, 2010). Currently, seven out of ten of older adults have periodontal disease, one out of five have untreated tooth decay, and one out of four have lost some or all of their teeth (Eke et al., 2012;No Authors, 2001). Optimal oral health can be achieved by, 1) strong commitment to maintain oral care that can be fostered by effective communication strategies on oral health information and programs; and 2) providing adequate ongoing professional care that can be accessed readily.
Oral health can be measured objectively by means of oral examinations by oral health professionals and also subjectively as reported by the individual. The use of subjective measures in evaluating oral health is well-established (Lee, Shieh, et al., 2007). There is a vast evidence showing that the perceived dental condition is closely related to the individual's oral health-related quality of life (OHRQoL), and may have a greater impact than the actual presentation of the clinical condition (Brennan & Spencer, 2006).

The United States (US) Surgeon
General's report on Oral Health in America emphasizes the importance of OHRQoL, and its improvement on a population-level is defined as a goal (Department of Health and Human Services, 2000).
The validated short form of oral health index profile (OHIP-14) is used to quantify patient outcome experiences, monitor oral health status on national level, and identify dental public health goals (Sanders et al., 2009).
Oral health literacy is the premise for better oral health and defined as "the degree to which individuals have the capacity to obtain, process and understand basic health information and services needed to make appropriate oral health decisions" (J Public Health Dent, 2005). Instruments that measure oral health literacy include, the REALD-30  and the TOFHLAiD (Gong et al., 2007). However, main shortcomings include that they primarily evaluate word recognition and reading comprehension, and fail to determine oral health knowledge. The Comprehensive Measure of Oral Health Knowledge (CMOHK) which was developed at the University of Maryland is a validated 23-item questionnaire (Macek et al., 2010), that focuses on determining basic oral health knowledge.
Upon completing the questionnaire, the individual's oral health knowledge can be assessed and categorized as good or poor.
Poor oral health literacy has been associated with inadequate oral health outcomes such as poor oral health status, dental neglect and sporadic dental attendance (Divaris et al., 2011;National   The questions were selected from two validated questionnaires (English and Spanish) and also specifically formulated for this study.
The questionnaire included: demographic information, daily oral hygiene procedures, dental utilization, oral health knowledge, and oral health related quality of life. Questions were selected and utilized verbatim or modified from the Comprehensive Measure of Oral Health Knowledge (CMOHK), and Short form of the Oral Health Profile Index .
Participants had the option to fill-out the questionnaire in English, Spanish, or a mix of English and Spanish. For data analysis, each question was scored as wrong or correct. Then the total number of correct answers was calculated. Originally knowledge scores were categorized into three categories: poor, fair, and good (Macek et al., 2010). We used a modified scoring system that better served our purpose, and knowledge scores were simply split into poor (0-14) or good (15-23) (McQuistan et al., 2014;Patino et al., 2018).
The short form of the Oral Health Impact Profile (OHIP-14) index was used to evaluate OHRQoL (Slade, 1997). OHRQoL impacts were assessed by calculating Severity (cumulative OHIP-14 score ranging from 0-56).
A sample size calculation was conducted in order to find an effect size of 0.2 (10% difference) in oral health knowledge between Caucasians and Hispanics. Based on the calculation, it was estimated that a minimum sample size of 60 per group should be obtained for 80% power, at an alpha level of 0.05.
Descriptive statistics were calculated for all dependent and independent variables. Independent variables were categorized into three domains: 1) demographics, 2) oral hygiene practices, and 3) dental utilization. Odds ratios were conducted to determine the factors associated with oral health knowledge and dental utilization within each domain and were reported with 95% confidence intervals with continuity corrections. The findings of descriptive analyses were reported as absolute frequencies or rates in the case of categorical variables, as medians in the case of quantitative variables with non-parametric distributions, and as mean ± SD in the case of quantitative variables with normal distributions. Quantitative variables were compared among the study groups by using one-way analysis of variance (ANOVA) or the Kruskal-Wallis test, as appropriate. Categorical variables were compared using the χ 2 test. Correlations among Oral Health Knowledge and Oral Health Profile Index Severity were conducted with Pearson Correlation. Binary multivariate logistic regression analysis with odds ratios and 95% confidence intervals was performed to identify independent variables predicting oral health knowledge and severity of oral health. p values < 0.05 were considered statistically significant. All data were analyzed using SAS version 9.4 and R 3.6.2.

| RESULTS
All surveys were collected and responses entered into a data spreadsheet. There were no limitations of skipped questions. Overall there were only two questions that were skipped by one participant. The skipped questions were counted as incorrect. Out of a total of 304 surveys 127 (41.8%) were filled out in the Spanish version.
Despite the option to use both the Spanish and English version together, there were no mixed versions. The ethnicity distribution of older adults aged 65 years and above for our study compared to the US Census of San Bernardino County is summarized in Table 1. Overall our study reflected the ethnicity distribution of San Bernardino County, with higher percentages observed in the Hispanic and Asian group while lower percentages were observed for the Caucasian group compared to the US Census records.
Other demographics, oral hygiene practices, and dental utilization are summarized in Table 2. Over two-thirds (67.8%) of the study sample was between the ages of 65 and 75 years. More than half of the participants were female (57.9%) or had more than high school education (60.5%). Less than half of the participants earned less than $25,000 (37.8%) or reported excellent reading ability (40.8%). Over two-thirds of the study sample brushed twice or more a day (70.4%) or used a manual toothbrush (69.7%). The majority of respondents received regular dental care (74.0%) while half had dental insurance (52.3%).
The mean OHK score was 13. Scores ranged from 0 through 23 points, with two participants having all questions answered incorrectly and one participant having all 23 responses correct. Overall the mean OHK score and SD were 16.8 (4.0), 14.6 (4.7), and 8.9 (4.7) for Caucasian, Asian, and Hispanics, respectively. There was a statistically significant difference among the three ethnicity groups (p < 0.05).
Approximately 56.9% of participants were identified as having "Poor" oral health knowledge (0-14 points). When looking at each question individually as summarized in Table 3, most participants correctly answered questions that pertained to general dental knowledge (except for questions on teeth numbers), dental treatment, and presentation of oral diseases. However, respondents were less likely to correctly answer questions that pertained to children's oral health, periodontal disease, and oral cancer. Higher percentage of correct responses for each question by ethnicity was generally in the order of Caucasian, Asian, and Hispanics.
Hispanic participants were nearly 25 times more likely to be identified as "Poor" oral health knowledge as compared to Caucasians. Asians were over 2.5 times more likely to be identified as 'Poor" OHK. When modeling for variables associated with poor oral health knowledge, ethnicity was the strongest factor followed by "How often they brush their teeth '(OR=5.73; 95% CI: 1.33-24.75)' and 'Reading Quality' (OR = 2.60; 95% CI: 1.36-4.95)." OHRQoL was assessed using a 5-point scale from 0 noting "never" to 4 noting "very often." The severity score ranged from 0 to 56 with a mean score of 16. Overall the mean OHIP severity score and SD were 7.4 (7.6), 12.5 (11.8), and 24.4 (15.9) for Caucasian, Asian, and Hispanics, respectively. There was a statistically significant difference among the three ethnicity groups (p < 0.001) with Caucasians having the lowest and Hispanics the highest severity. Most participants responded never or hardly ever to the question pertaining to inability to function because of problems with their teeth or mouth while most participants reported occasionally experiencing painful aching in the mouth, discomfort while eating food, and feeling selfconscious because of their teeth and mouth. Severity was significantly higher (p < .001) for participants with "Poor" oral health knowledge (Median = 19; IQR: 8-33) as compared to participants with "Good" oral health knowledge (Median = 6; IQR: 2-12). Respondents with Poor OHK were 5.17 times more likely to be identified with high levels of severity (Severity >10). The strongest factor associated with severity (>10) was Education of High School or less (OR = 3.93; 95%

| DISCUSSION
Older adults are a vulnerable population that can suffer disproportionately from a variety of diseases. Although often recognized as a single cohort, older adults are a diverse population, spanning 35 plus years.
Generally, adults between 65 to 75 years are defined as the "young old," 75 to 85 years as the "old," and 85 years and above as "old old." Within each category, older adults have distinct cultural, psychological, educational, social, economic, dietary and chronological experiences that define their life and way of thinking (Ettinger & Beck, 1984;Ettinger & Mulligan, 1999).
Our study evaluated oral health knowledge and oral health related quality of life of older adults among different ethnicities living in San Bernardino County, California. Over two thirds of participants belonged to the "young old" category and the majority were living in the community. Thus, the main focus of our study was related to functionally independent older adults (Ettinger & Beck, 1984;Ettinger & Mulligan, 1999). It is important to note that compared with previous generations, the current older adults are more likely to retain their teeth and consequently more likely to experience periodontal disease, root caries, and oral cancer (Ettinger & Beck, 1984;Ettinger & Mulligan, 1999;Qualtrough & Mannocci, 2011 Poor OHK was associated with increasing age, education, ethnicity, income, and reading ability. When modeling for variables associated with poor oral health knowledge, ethnicity was the strongest factor with Hispanic participants nearly 25 times more likely to be identified as "Poor" oral health knowledge as compared to Caucasians. Based on our results we rejected our null hypothesis, since there was a difference in OHK among different ethnicities. The concern of poor OHK among Hispanics was also pointed out by a study that evaluated the OHK specifically in the Hispanic population. Despite the lower mean age of 38 years, the mean OHK in that study was still low at 14 (Patino et al., 2018). The knowledge gap existed in areas of children's oral health, periodontal disease, and oral cancer which was in accordance with our study.
An interesting finding of our study that has not been noted in other literature was that less than half of participants were not knowledgeable about the number of permanent teeth in adults. Tooth loss is an important indicator of oral health and the number of teeth affect the ability to chew, speak, and socialize. The California Oral Health Plan 2018-2028 (California Department of Public Health, 2018), outlines an objective to reduce the proportion of adults who have ever had a permanent tooth extracted because of dental caries or periodontal disease. Based on goal setting theories, to improve health behavior change and maintenance interventions, it is important to target specific goals leading to higher performance when compared with no goals or vague, nonquantitative goals such as preserve as many teeth as possible (Strecher et al., 1995). Therefore, from a knowledge where the mean age was 43 years and the mean severity score was 4.9 (Sanders et al., 2009 F I G U R E 1 Scatterplot of relationship between oral health knowledge and oral health profile index severity by ethnicity groups