Observation of soft food chewing ability with HA-contained chewing gum

Objectives: There were various objective methods for measuring masticatory function reported in previous studies. The sieve method is generally used for hard food chewing efficiency evaluation. For soft food chewing ability evaluation, the ability of mixing ingredients in a chewing gum had been proposed and used. However the validity and efficacy of such methods had not been well evaluated. The purpose of the present study was to develop a soft test food with reasonable observation method for soft food masticatory function evaluation. Methods: A block of chewing gum containing 0.02g of hydroxylapatite granules (HA) was chewed by 25 young subjects who had complete dentition and healthy masticatory system. Homogeneity of HA in the chewed gum bolus was measured after sessions of 5,10,15,20,25,30 chews of the HA-gum blocks. A 2mm thick chewed gum bolus was prepared for digital X-ray observation. Presence and distribution of HA particles were observed with MatLab computerized image analysis program. The homogeneity of HA particles shown in the field of a gum bolus was defined as the mixing efficiency (ME) of that chewing session. Linear regression and Student's t test were applied for evaluating the relationship between chewing stroke number and ME. Results: The mean mixing ability of 25 subjects increased consistently from 5 to 20 chew strokes (R2=0.99, P=0.005). A plateau was seen after 25 chew session. HA homogeneity varied from 29.01% to 71.96 %. Significant increase of ME between consecutive chewing sessions were found among 5,10,15 and 20 strokesessions (p<0.0005). Conclusions: The HA particle contained chewing gum and the computerized observation method can objectively evaluate the soft food mixing ability of human subjects. This method will be used for further studies on the comparison of soft food chewing ability with different dentitions or restorations.