Use of Hand Fingers as an Index for Natural Mouth Opening in Dental Faculty Students of Tabriz University of Medical Science

The range of mouth opening is a diagnostic sign in some clinical situations and has importance in treatment management. In order to distinguish decreased mouth opening, it is essential to establish normal range of the mouth opening in a certain population. The purpose of this study was to determine the normal range of the mouth opening by using hand fingers in students of dental faculty of Tabriz University of Medical Sciences in 2009. One hundred and fifty dental students (aged 19-47 years, the mean age of 27.94±8.10 years) were examined and divided into two groups; with and without temporomandibular joint dysfunction. Ability of subjects in putting three fingers (index, middle and ring finger) or four fingers (index, middle, ring and little finger) at vertical position in the mouth were evaluated. Furthermore, amount of maximum mouth opening and the width of three and four fingers of both hands were measured. Seventy four percent of the subjects could put three fingers in the mouth, whereas 15.3% were able to put four fingers in the mouth. In addition, 10.7% of the participants were not able to put three fingers in the mouth. The mean of maximum mouth opening was 51.87±7.6 mm. According to this study, individuals’ fingers are not appropriate index for assessing the normal range of the mouth opening in subjects with or without temporomandibular joint dysfunction.