title: Efficiency of Closed Mastication of Gummy Evaluated with Gnatho-hexagraph.
abstract: The aim of this study was to determine whether chewing with closed lips improved masticatory efficiency compared with open lips. A total of 21 adults comprising 10 men and 11 women with a mean age of 26.2±3.5 years and normal masticatory function were included in the study. The study participants were instructed to chew a fresh gummy under two conditions for 30 seconds each, one after the other: the first with closed lips, and the second with open lips. The average size of the fragmented gummies was calculated and graded from 1 to 4 according to a specific scale. Masticatory efficiency was evaluated using this "gummy mastication value" and the Gnatho-hexagraph II to observe and analyse jaw movement during chewing. Differences in chewing time and mouth-opening distance were also compared. The gummy mastication value for open and closed lips mastication was 2.51±0.56 and 3.25±0.50, respectively (p<0.01). Masticatory efficiency was significantly greater during closed-lip mastication. The number of chewing strokes over 20 seconds decreased while chewing time and mouth-opening distance increased in cycle 1 with open-lip mastication. In conclusion, the present results revealed that chewing efficiency improved with closed-lip mastication, indicating that instruction to seal the lips while eating is appropriate and necessary.
authors.affiliation: Yoshii Orthodontic Clinic.
authors.forename: Chiharu
authors.initials: C
authors.lastname: Shima
authors.forename: Etsuko
authors.initials: E
authors.lastname: Motegi
authors.forename: Akiyo
authors.initials: A
authors.lastname: Horiuchi
authors.forename: Takenobu
authors.initials: T
authors.lastname: Ishii
authors.forename: Mayumi
authors.initials: M
authors.lastname: Nomura
authors.forename: Makoto
authors.initials: M
authors.lastname: Nakao
authors.forename: Kenji
authors.initials: K
authors.lastname: Sueishi
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008046:Lip; D008297:Male; D008409:Mastication; D009068:Movement; D055815:Young Adult