• Porntip Chiewcharat
• Niramol Chamnannidiadha
• Chaiyasri Thunpithayakul
• Teera Thammawasi
• Piyarat Chalermsuksunt

Objective  The purpose of this study was to compare the relationship between upper dental midline and other reference positions, namely, frenum, incisive papilla, and midpoint of the second rugae.

Materials and methods  The investigation was conducted on 60 upper dental casts which were selected by purposive sampling method according to the required criteria that was deviation of upper dental midline from facial midline based on histories of patients who came for orthodontic treatment at the Department of Orthodontics, Faculty of Dentistry, Chulalongkorn University. By fixing the 4 positions mentioned above and using the posterior part of the midpalatal raphe as a reference line measurements in millimeters could be made with an instrument modeled on Bernklau symmetrograph. The distances of the 4 positions from reference line were then used for statistical correlation study.

Results  Statistical analysis revealed that upper dental midline was significantly correlated to frenum and incisive papilla but there was no correlation between upper dental midline and midpoint of the second rugae.

Conclusion  Among the four different median line reference points, a midpoint of the second rugae was a landmark that did not significantly relate to the upper dental midline and thus may help identify the midpalatal plane on the upper dental cast.

(CU Dent J 2001;24:159-66)