• Porntip Chiewcharat B.Sc. (Hons.), D.D.S. (Hons.), M.D.Sc. (Orthodontics), Diplomate, Thai Board of Orthodontics
• Niramol Chamnannidiadha B.Sc. (Hons.), D.D.S. (Hons.), Dr.med.dent, Diplomate, Thai Board of Orthodontics
• Ruckporn Laosuithiwong B.Sc. (Hons.), D.D.S. (Hons.), M.D.Sc. (Orthodontics)
• Achara Nantaseang
• Ekachai Poobalee

Objective The purposes of this study were to determine prevalence of unilateral chewing habit and
its related factors in a group of Thais with normal occlusion and a group of orthodontic patients.

Materials and methods The samples consisted of a group of 100 orthodontic patients (41 males and
59 females) from the Department of Orthodontics, Faculty of Dentistry, Chulalongkorn University and
a group of 100 Chulalongkorn University students with normal occlusion (45 males and 55 females).
The data were collected by completing the chewing habit questionnaire. Descriptive statistics were
used to find the prevalence and Chi-square test was used to find the related factors of unilateral
chewing habit.

Results The prevalence of unilateral chewing habit was statistically significant higher (p < 0.05) in the
orthodontic patient group (51%) than in the normal occlusion group (28%). In the orthodontic patient
group, there was no statistically significant difference among 10 related factors of unilateral chewing
habit (p > 0.05), but there was the relationship between the factor of temporomandibular joint pain
and the unilateral chewing habit in normal occlusion group (p < 0.05).

Conclusion The prevalence of unilateral chewing habit in the orthodontic patient group is higher
than that of the normal occlusion group. No related factor to unilateral chewing was found in the
orthodontic patient group, whereas temporomandibular joint pain was found to be a related factor in
the normal occlusion group.

(CU Dent J. 2010;33:155-62)