Mercurial risk from dental amalgam use in a population of Moroccan dentists: A latent class regression approach.

BACKGROUND: Dentists using dental amalgam are chronically exposed to low doses of elemental mercury. The complex toxico-kinetics of this systemic toxicant results in polymorphic and variable clinical phenotypes. In this context, adapted statistical methods are required to highlight potential adverse effects of occupational mercury exposure on dentists' health. OBJECTIVE: The present study aims to analyze the distribution of self-reported subjective symptoms, commonly associated with chronic mercury poisoning, according to occupational mercury exposure in a population of Moroccan liberal dentists. METHODS: In order to achieve the defined objectives, a three-step latent class regression was fitted. First a latent class analysis was performed to cluster the studied population according to their declared symptoms. Dentists were then classified in the defined latent classes based on their posterior probabilities. Finally, a logistic regression is fitted to identify predictors associated with the latent classes' membership. RESULTS: The final obtained model showed acceptable calibration and discrimination. Its interpretation revealed that the increase of the frequency of amalgam use was associated with significant higher odds of belonging to the high risk latent class. CONCLUSIONS: The present study represents an initial step towards the development of diagnosis model that predict clinical profiles according to occupational mercury exposure.

Preventive planning against mercury over-exposure among Moroccan dentists using multidimensional statistical methods.

BACKGROUND: Mercury used in dental amalgams constitutes a significant source of chronic exposure to this heavy metal among dentists. Thus, the safety of dental amalgam remains a controversial issue despite its long history of use. In Morocco, most studies about dental mercury were mainly focused on the environmental risk related to the management of mercury-contaminated waste. OBJECTIVE: In order to evaluate the occupational exposure to mercury among liberal dentists practicing in two Moroccan regions, a multidimensional statistical approach was used to analyze the collected data. The main objective was to help establishing a targeted prevention plan aiming to reduce the mercury exposure among Moroccan dentists. METHODS: Fifteen variables from 146 dentists were elected for a three-step classification procedure: a multiple correspondence analysis followed by a hierarchical ascendant clustering consolidated by the k-Means algorithm. RESULTS: Three homogenous clusters were identified. The most important one includes 57.5% of the population as well as the majority of the risky factors. The characterization of these clusters allows proposing concise guidelines for a targeted preventive plan. CONCLUSIONS: A real mercurial risk has been observed in the studied population. However, its impact on health as well as the efficiency of simple preventive recommendations remains to be unveiled.

Modeling Subjective Symptoms Related to Micro-Hydrargyrism in a Population of Moroccan Dentists.

BACKGROUND: The ability of mercury to deposit throughout the body and alter a wide range of molecular and cellular pathways results in a polymorphic and complex clinical phenotype with over 250 possible symptoms. However, some of them are recurrently cited as evoking chronic mercury poisoning. In this light, dentists users of dental amalgams are chronically exposed to mercury so that in-depth epidemiological investigations and adapted statistical methods are required to highlight adverse effects of this exposure. METHODS: In order to study the health impact of the occupational mercury exposure in a population of liberal dentists practicing in two Moroccan regions, a list of eighteen subjective symptoms commonly associated with micro-hydrargyrism was drawn up. Then, seven statisctical models adapted to count data were fitted. Finally, three methods were used to compare their relative performance in order to choose the most appropriate one. RESULTS: The adopted logical path, from the response variable selection till models' comparison, led us to lean towards quasi-Poisson regression as the best way to predict the number of symptoms declared by dentists according to mercury exposure. CONCLUSIONS: Interpretation of the selected model allowed us to conclude that the reduction of dental amalgam use allows the reduction of subjective symptoms related to mercury exposure.

[Mercury exposure and dentists' health status in two regions of centrall Morocco: descriptive cross-sectional survey]. / Exposition au mercure et état de santé des médecins dentistes de deux régions du centre du Maroc: enquête transversale descriptive.

INTRODUCTION: mercury exposure is recognized as a worldwide public health concern. However, the effect of long-term exposure to low-doses of this heavy metal is still subject to debate. Due to the use of mercury in dental amalgam, dental health care professionals are chronically exposed to low-doses of this metal. In this context, we have conducted a descriptive cross-sectional survey among liberal dentists in two regions of the center of Morocco. In parallel, the global health status of participants was investigated to assess the relevance of a subsequent etiological survey. METHODS: data were collected through a self-reported questionnaire. Occupational exposure of dentists to mercury was evaluated based on their use of dental amalgam. Moreover, the other common factors increasing the background pollution or inducing exposure peaks were also investigated. On the other hand, smoking, vaccination, fish consumption, and the number of dental amalgam in mouth were considered as non-occupational exposure sources. Finally, the self-reported global health problems of participants were collected. RESULTS: 192 dentists were included in the present study. Seventy-six percent (76.04%) of them declared using dental amalgam in their practice. Moreover, the presence of dental amalgam in mouth was identified as the main non-occupational source of exposure to mercury (63.45% of participants). Finally, most of participants (46.35%) have expressed neuropsychological complaints. CONCLUSION: altogether, our results revealed a real mercury exposure in the studied population. Thus, effective preventive measures should be promoted to minimize the mercury exposure in dental offices. Moreover, an etiological study will be of great interest to reveal the impact of mercury exposure in this population.