Chewing Performance of TMD vs. Controls: A New Experimental Model
Qureshi, Zohair M.
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Objectives: Limitations in masticatory function are a common complaint by patients with TMD. However limited published data exists to conclusively identify subjective and objective parameters of mastication and the impact of TMD on mastication. This study focused on developing a new measurement approach using optical scanning to measure particle size, testing its utility and identifying relationship between subjective and objective indicators of performance as related to TMD. Materials and methods: In Study1, standard objects of various size and shapes were used to develop a valid scanning protocol. The findings were then confirmed on a predetermined sample of Optosil®. In Study2, subject reliability and the best parameters for measuring chewed Optosil® were identified. Twenty subjects, 10 TMD and 10 controls were given two trials of 2 grams of Optosil® to chew at a rate of one chew per second for forty seconds, expectorated, rinsed, dried and spread on a glass slab on a flatbed scanner. Method and subject reliability was assessed using the ICC statistic. Study 3 included additional hypothesis testing of a third trial and constrained vs. habitual chewing on 20 asymptomatic controls with 6 trials of Optosil® each. Study 2 and 3 identified trial 2 as the representative trial for a subjects' true performance. In Study 4, overall utility of the experimental design was tested with only trial 2 for fifty three subjects, 33 cases (TMD):20 controls for parameters "pain", "limitation" and "efficiency" along with particle count and size estimates. Data analysis was done using Stata. Reliability testing was done using ICC and Spearman correlation. Hypothesis testing was done with Kruskal Wallis and computing χ 2 distribution for comparison between groups. Results: a reliable and valid protocol using optical scanning for objective analysis of chewed test food was developed which is sufficiently sensitive to differentiate TMD from controls. TMD subjects chew slightly less efficiently compared to controls. This slight decrease in masticatory performance of TMD compared with controls is disproportionate to the reported masticatory performance, which is markedly lower in TMD compared to non-TMD. Conclusions: The optical measurement method is valid and reliable for 5 of 6 parameters with respect to chewed Optosil® particles. These results demonstrate that individuals with TMD chew less well compared to controls.