Differences in Contact-Area Between Children From an Urban/Rural Community

Objectives: One of the factors that strongly influences masticatory performance(MP) is the contact area(CA). This factor has not been studied in children with different lifestyles (urban vs rural).The objective was to compare CA in children from an urban and a rural community and to relate it to their MP and maximum occlusal force(MOF).
Methods: A prospective cross-sectional study on 8-10 year old children (n=52, Mexico City; 53, from a small town in Oaxaca, Mexico) was performed. CA (≤350 µm) at maximum intercuspation was obtained from a polyvinyl-siloxane(Imprint-Bite®) occlusal registration (both sides 1^st deciduous to 1^st permanent molar) which was digitalized and analyzed using specialized software(Image-Tool,UTHSCSA). Medium particle size(MPS) as a measure of MP was obtained using a standardized artificial test food (after 20 chewing cycles and swallowing threshold/ST). The number of cycles used to reach ST was visually counted. MOF was obtained using a force transducer(GM10-Nagano-Keiki,Japan) on molars. Comparisons between groups as well as correlations to analyze relationships between variables were performed. A stepwise multiple regression analysis was used to identify explanatory variables.
Results: The children from the rural area had significantly higher values of CA (median 29 vs. 23.5mm²), MOF (592±106vs519±122N), smaller MPS after 20 cycles and at ST(2.7vs3.1mm; .9vs1.2mm respectively)and used more cycles(51vs39) before ST than those from Mexico City. We found significant correlations between MPS(20cycles), CA, and MOF and between MPS(ST), CA, MOF and number of cycles till ST. Multiple regression analysis showed that CA, MOF and community explain 28% of the variation in masticatory performance after 20 cycles and MOF, number of cycles till ST and community explain 46% of MP at ST.
Conclusions: Children from the rural area had broader occlusal contacts which were related to and contribute to their higher MOF and better MP.
Grant: PAPIIT; UNAM, IN220413.