• Phanomporn Vanichanon DDS.(Hons), M.S., M.Sc.
• Khanittha Saisud
• Jintana Yooyen
• Nattapong Labueng

Objective To find out the extent to which subjects can move their jaws to the correct position
following the dentistûs instructions, and to determine the most appropriate instruction method to enable
subjects to move their jaws correctly.

Materials and methods A sample of 18 dental faculty staff were interviewed to ascertain the
methods they used to instruct patients to move their jaws to different positions, as follows: 1) the
intercuspal position (ICP); 2) right-left lateral excursion; 3) protrusion; and 4) maximum mouth
opening (MMO). Then the four most popular methods were selected and tested on 102 subjects.
All positions were checked by one faculty staff. For MMO, it was assumed that the method which
achieved the greatest interincisal distance was the correct one.

Results The extent to which the subjects could correctly move their jaws depended on the instruction
method (p < 0.05). The best methods, which brought the subjects to the most correct jaw positions,
were: 1) For the ICP: the dentist touched the subject's cheek in the posterior tooth area and said,
"Bite on this area" (91.2%); 2) Right and left lateral excursion: the dentist said, "Move your jaw to the
right" [or "left"] as the subject held and looked into a mirror (84.3% and 79.4%, respectively);
3) Protrusion: by the dentist's demonstration (97.1%); and 4) For maximum mouth opening: the dentist
said, "Open your mouth as wide as you can then" followed by "Can you open wider?" (65.09%).

Conclusion Each subject had a different ability to move the jaw into the correct position following
the dentistûs various instruction methods. Mistakes most often occurred at the lateral excursion.

(CU Dent J. 2009;32:213-24)