Biomedical subjects

Anwar T Merchant

Publications and source records attributed to Anwar T Merchant.

26 records · Page 2Linked to original sources

PubMed2004

Can nonstandardized bitewing radiographs be used to assess the presence of alveolar bone loss in epidemiologic studies?

OBJECTIVE: To compare periodontitis-associated alveolar bone loss assessment by standardized and nonstandardized radiographs in clinical and epidemiologic studies. METHODS: Participants included 37 patients aged 21-66 years with prior nonstandardized bitewing radiographs scheduled to receive bitewing radiographs as part of their next routine dental care visit. Standardized bitewing radiographs were taken with a Rinn film holder to position the film in the mouth and align the X-rays so that they were at 90 degrees to the film. Before taking the radiograph the bite was registered in centric relation using a polyether impression material. One registered dental hygienist took and processed all the standardized radiographs. One dentist read all radiographs using a viewing box, magnifying lens, and periodontal probe with William's markings. Radiographic bone loss was measured to the closest millimeter at mesial and distal sites of the posterior teeth excluding third molars. The examining dentist was blinded to the participant's name, age, gender, or if the radiograph was standardized or nonstandardized. RESULTS: Mean bone loss (+/- SD) was similar in the standardized and nonstandardized groups (1.60 +/- 0.72 mm versus 1.64 +/- 0.85 mm), and the correlation was high (r = 0.95). Periodontitis was defined as present if the participant had at least one site with 3, 4 and 5 mm bone loss. The Kappa statistics for concordance using these three cutoffs were good and ranged from 0.60 to 0.65. The sensitivity ranged from 72.7 to 80.8% and specificity from 88.5 to 90.9%. CONCLUSIONS: Periodontitis assessed as mean alveolar bone loss or the prevalence of disease based on alveolar bone loss can be accurately and reliably evaluated from nonstandardized radiographs.

Adult↗

PubMed2004

Use of preexisting radiographs for assessing periodontal disease in epidemiologic studies.

OBJECTIVES: This study evaluates the feasibility of obtaining preexisting dental radiographs by mail, the validity of assessing alveolar bone loss from posterior radiographs compared to full mouth, and the validity of alveolar bone loss assessed from radiographs taken at different times. METHODS: This investigation uses data obtained for a study evaluating associations between oral conditions, blood biomarkers, and coronary heart disease within two large cohorts: the Nurses' Health Study and the Health Professionals Follow-up Study. If consenting participants had dental radiographs, we requested these radiographs from their dentists. Some dentists returned multiple sets of radiographs, which enabled us to conduct this study. A calibrated periodontist read all radiographs with good intraexaminer reliability (r=0.91). We compared posterior radiographs to full mouth (n=121 sets), as well as radiographs taken at different times (mean difference of 5 years) (n=102 pairs). RESULTS: Of the 812 participants, 81 percent consented and 66 percent provided radiographs. Posterior radiographs underestimated periodontitis (> or =1 site with > or =5 mm alveolar bone loss) prevalence by 6 percent (53.7% vs 57.0%) compared to full mouth, with sensitivity of 0.94 (95% confidence interval [CI]=0.86, 0.98) and specificity of 1. Spearman correlation coefficients comparing mean alveolar bone loss were 0.70 for anterior versus posterior teeth (mean difference=0.48), 0.92 for posterior teeth versus full mouth (mean difference=0.25), and 0.78 for pairs of radiographs taken at different times (mean difference=0.01). The kappa statistic was 0.70 comparing radiographs taken within 5 years and 0.29 when the period extended beyond 5 years. CONCLUSION: Preexisting radiographs are feasible for use in epidemiologic studies and provide valid assessments of periodontal disease.

Adult↗

PubMed2003

Serological response and poliovirus excretion following different combined oral and inactivated poliovirus vaccines immunization schedules.

A controlled study was conducted in Karachi, Pakistan to compare humoral and mucosal immune responses against polioviruses in infants who received oral poliovirus vaccine (OPV) at birth and at 6, 10, and 14 weeks according to the Expanded Program on Immunization (EPI) with infants who received either three doses of inactivated poliovirus vaccine (IPV) at 6, 10, and 14 weeks together with OPV or one additional dose of IPV at 14 weeks together, with the last dose of OPV. A total of 1429 infants were enrolled; 24-week serum specimens were available for 898 infants (63%). They all received a challenge dose of OPV type 3 at 24 weeks of age. The addition of three doses of IPV to three doses of OPV induced a significantly higher percentage of seropositive children at 24 weeks of age for polio 1 (97% versus 89%, P<0.001) and polio 3 (98% versus 92%) compared to the EPI schedule. However, the one supplemental dose of IPV at 14 weeks did not increase the serological response at 24 weeks. Intestinal immunity against the challenge dose was similar in the three groups. Combined schedules of OPV and IPV in the form of diphtheria-pertussis-tetanus-IPV vaccine (DPT-IPV) may be useful to accelerate eradication of polio in developing countries.

Antibodies, Viral↗

PubMed2003

Increased physical activity decreases periodontitis risk in men.

BACKGROUND: Increased physical activity improves insulin sensitivity and glucose metabolism, and may therefore affect incidence of periodontitis. METHODS: We studied the association of physical activity, walking and periodontitis in 39,461 male, US based, health professionals, 40-75 years old at baseline, more than half of whom were dentists, being followed up continuously since 1986. Participants were free of periodontitis, coronary heart disease and stroke at the start of follow-up. Physical activity and periodontitis were measured by validated questionnaires (expressed in metabolic equivalents--METs); the first report of professionally diagnosed periodontitis was considered a case. RESULTS: Periodontitis risk decreased by 3% for every 10-MET increase in average physical activity after adjustment for age, smoking, diabetes, BMI, alcohol consumption and total calories (RR = 0.97; 95% CI: 0.95-0.99). The inverse trend remained significant in the categorical analysis. Compared to men in the lowest quintile of physical activity, those in the highest quintile had a 13% lower risk of periodontitis (RR = 0.87; 95% CI: 0.76-1.01, p-value, test for trend = 0.02). In a sub-sample of men with radiographs (n = 137) the physically active had less average bone loss (beta = -0.29, p-value = 0.03) after multivariate adjustment compared to those inactive. CONCLUSIONS: In this large-scale prospective study, we found an inverse, linear association between sustained physical activity and periodontitis independent of known risk factors. The benefits of a physically active lifestyle may extend to periodontal health.

Adult↗

PubMed2003

Dietary fiber reduces peripheral arterial disease risk in men.

We prospectively evaluated the relationship between dietary fiber and peripheral arterial disease risk (PAD) among 46,032 men, aged 40 to 75 y, in 1986. Subjects answered a vascular disease questionnaire and completed a validated 131-item food frequency questionnaire, and were free of PAD, cardiovascular disease and diabetes. During 12 y of follow-up 308 incident PAD cases were documented. After adjusting for age, smoking, hypertension, hypercholesterolemia, family history of early coronary heart disease, alcohol consumption, BMI, physical activity and energy intake, PAD risk in each quintile of cereal fiber intake compared with the lowest quintile was 0.69, 95% CI 0.49-0.97 for quintile 2; 0.65, 95% CI 0.45-0.94 for quintile 3; 0.68, 95% CI 0.47-0.98 for quintile 4; and 0.67, 95% CI 0.47-0.97 for quintile 5. In a nonlinear model the overall inverse association (P = 0.02) and nonlinear components (P = 0.03) were significant. Fruit, vegetable and total fiber intakes were not associated with PAD risk. These results suggest an inverse association between cereal fiber intake and PAD risk in men. Increasing cereal fiber intake may prevent PAD.

Adult↗

PubMed2003

The use of B vitamin supplements and peripheral arterial disease risk in men are inversely related.

Peripheral arterial disease (PAD) causes morbidity and is associated with mortality. B vitamin intake has been inversely associated with coronary heart disease, but their effects on PAD are not known. We examined prospectively the relationships between dietary folate, vitamin B-6 and B-12 and PAD risk in 51529 male U.S. health professionals, aged 40 to 75 y, who answered a detailed 131-item questionnaire to assess diet and vitamin supplement use. The study population consisted of 46036 men free of PAD, cardiovascular disease and diabetes at baseline followed for 12 y during which we documented 308 incident PAD cases. For every 400 microg/d increment of folate intake, the multivariate adjusted PAD risk decreased by 21% [relative risk (RR) = 0.79, 95% CI 0.64-0.96]. Men in the top category of folate intake (median = 840 micro g) were at 33% lower risk of PAD than men in the bottom category (median = 244 microg) (RR = 0.67, 95% CI 0.45-0.96, P-value, test for trend = 0.03) after multivariate adjustment. There were weak inverse associations between intake of vitamin B-6 and PAD risk (RR = 0.70, 95% CI 0.48-1.02, P-value, test for trend = 0.06) and B-12 (RR = 0.77, 95% CI 0.54-1.11, P-value, test for trend = 0.12). These results suggest that higher consumption of folate may contribute to the prevention of PAD.

Adult↗

PubMed2003

A prospective study of social support, anger expression and risk of periodontitis in men.

BACKGROUND: Stress is associated with poor oral hygiene, increased glucocorticoid secretion that can depress immune function, increased insulin resistance and potentially increased risk of periodontitis. METHODS: The authors examined the association between social support, anger expression and periodontitis in 42,523 male, U.S.-based, health professionals. Subjects were aged 40 to 75 years in 1986, and more than half were dentists. The men were free of a diagnosis of periodontitis at the start of follow-up in 1996. RESULTS: Subjects who reported having at least one close friend had a 30 percent lower risk of developing periodontitis compared with those who did not have a close friend (relative risk, or RR = 0.70; 95 percent confidence interval, or CI, 0.51-0.96). Men who participated in religious meetings or services had a 27 percent lower risk of developing periodontitis compared with men who did not participate in religious meetings (RR = 0.73; 95 percent CI, 0.64-0.83). After the authors adjusted for potential confounding variables, men whose anger scores were in the top quintile were 72 percent more likely to report having periodontitis compared with men whose scores were in the lowest quintile (RR = 1.72; 95 percent CI, 1.39-2.12). Men who reported being angry on a daily basis had a 43 percent higher risk of developing periodontitis compared with men who reported being angry seldom. CONCLUSION: Reduced social isolation and anger expression may play an important role in maintaining oral health, as well as general health and well-being. CLINICAL IMPLICATIONS: When treating patients with periodontitis, clinicians should be cognizant of the social and behavioral factors that may affect oral health.

Adult↗

PubMed2002

Directed acyclic graphs (DAGs): an aid to assess confounding in dental research.

Confounding, a special type of bias, occurs when an extraneous factor is associated with the exposure and independently affects the outcome. In order to get an unbiased estimate of the exposure-outcome relationship, we need to identify potential confounders, collect information on them, design appropriate studies, and adjust for confounding in data analysis. However, it is not always clear which variables to collect information on and adjust for in the analyses. Inappropriate adjustment for confounding can even introduce bias where none existed. Directed acyclic graphs (DAGs) provide a method to select potential confounders and minimize bias in the design and analysis of epidemiological studies. DAGs have been used extensively in expert systems and robotics. Robins (1987) introduced the application of DAGs in epidemiology to overcome shortcomings of traditional methods to control for confounding, especially as they related to unmeasured confounding. DAGs provide a quick and visual way to assess confounding without making parametric assumptions. We introduce DAGs, starting with definitions and rules for basic manipulation, stressing more on applications than theory. We then demonstrate their application in the control of confounding through examples of observational and cross-sectional epidemiological studies.

Bias↗