An adaptation of the Behavioral Model provides the conceptual approach for this study. The exogenous variables include ethnicity and age; while personal characteristics include education and income; and oral health behavior include both positive (flossing) and negative health behaviors (alcoholic consumption and tobacco use).
A community-based sample of 240 low-income immigrant Mexicans and other Latino immigrants being served by two UCLA community dental clinics was recruited in Venice, California from January-September 1993 to provide insight into the oral health status of Mexicans and other Latinos living in Venice, California (a section of the City of Los Angeles). Prior to this assessment, no other dental documentation existed concerning Latinos in Los Angeles. Venice has a population of over 31,000. Latinos comprise one-quarter of this population (7,750), and Mexicans comprise three-quarters of the total Latino population (5,813). The composition of this foreign-born sample was 157 Mexicans and 83 other Latinos. At the time of the study, Latino subgroups living in the Zip Code of the Venice Clinic had an average age of 36 years and incomes≥$12,000-$19,999. Over 50% of the participants in our sample had incomes≤$12,000. Even when this comparison is projected to the 2000 census data (no data was available from the 2010 census data), the participants in this study had lower incomes.
A flyer describing the study, in English and Spanish, was posted in waiting rooms of medical clinics serving this population in Venice as well as the two participating dental clinics. All participants signed an English or Spanish language consent form approved by the Institutional Review Board of the University of California, Los Angeles before any clinical examination or interview took place. Participants were given a $5 honorarium if they completed an interview and a clinical dental examination. Although a few of the participants were scheduled as new patients, the vast majority were not clinic patients, but accompanied their children or other members of their family to the clinic. Of those in our sample who sought treatment, none received treatment prior to the administration of the interview and examination. Almost all persons who were asked to participate in the study agreed to do so. Of those who declined, the majority did so because of time constraints and their concerns about missing work. Only completely edentulous persons were excluded. The resultant sample compared favorably with the population of Latinos that reside in the Zip Codes contained in the Venice community; in terms of average age, however, their incomes were slightly lower.
One interviewer who was bilingual and fluent in Spanish, and familiar with dental terms was trained and conducted face-to-face interviews with each subject. Interviews were conducted mostly in Spanish. Demographic questions included age, gender, income, education, ethnic classification, and country of birth. The behavioral questions covered measures on brushing, flossing, tobacco use, and alcohol use.
Prior to the study, two dental examiners were standardized to the criteria and then calibrated using patients from the dental clinic. The senior of the two examiners served as the reference examiner. Duplicate examinations were conducted throughout the study to determine intra-examiner and inter-examiner reliability. The National Institute of Dental and Craniofacial Research (NIDCR) clinical criteria were used for examining tooth status and measures of periodontal destruction.. Using weighted kappa values, intra-examiner reliability ranged from 0.7 to 0.9 and inter-examiner reliability from 0.5 to 0.8 depending on the specific index. The senior examiner performed approximately 80% of the examinations. All examinations were conducted in a dental operatory using current infection control methods and barrier techniques. Radiographs were not used during the clinical examinations.
The oral health status index
The OHSI is an outcome measure that combines and weights the status of the teeth (frank decay, missing and replaced) and periodontium (i.e., specifically attachment level) into one numerical score. A more detailed description of the OHSI and its calculation is given in previous papers[8, 20]. The five components of the OHSI are: Decayed Teeth (DT); Missing Teeth (MT); Free Ends, referring to the number of quadrants in the mouth in which all molars are clinically missing; Replaced Teeth (RT); and millimeters of Attachment Loss (AL) at the mesial facial surface that was subdivided into 4 to 6 mm of moderate AL and>6 mm of severe AL. Scores are based on 32 teeth, and whole mouth scores per person.
In order to determine the adequacy of the sample, a power calculation separated the Mexican immigrants from the other Latino immigrants. The power was calculated using mean OHSI scores as well as mean number of sound teeth. According to these calculations, 45 subjects in each group will yield 90% power to detect a difference of 4.60 OHSI units, between the Mexican immigrants and other Latino immigrant groups using a two-tailed 5% significance level. Therefore, there were sufficient numbers in our sample to determine significant differences. The descriptive analysis focused on the demographic and clinical measures (i.e., the Decayed, Missing, Filled permanent Teeth [DMFT] and periodontal disease measures). For the bivariate and multivariate analysis, the DMFT was transformed into percentage of decayed over decayed plus filled teeth, a measure of unmet needs for fillings; number of replaced teeth over missing teeth multiplied by 100 resulting in a ratio percentage that represents the degree of missing teeth that have been replaced. Chi-squared, paired t-tests and ANOVA were used to determine significant differences in the bivariate analysis. Multiple linear regression analysis, using the method of ordinary least squares, was used on epidemiologic measures with incremental addition of predisposing and enabling demographic and behavioral variables. The dependent variable in this analysis is the OHSI, and the independent variable is the place of birth, i.e., Mexico or other Latin American country. Covariates included epidemiologic, demographic and behavioral variables.