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5/29/2016 Influence of Functional Head Postures on the Dynamic Functional Occlusal Parameters

existence of any signs or symptoms of temporomandibular disorders (TMD).

Head postures

Head postures evaluated in the study were the supine, normal upright sitting and alert feeding position (30°
flexion). Rationale of including supine position was due to the fact that most of the dentist uses this chair position
during restorative procedures. 30° flexion was included as active feeding head position based on the earlier research
findings. Goniometer was used to standardize all the head postures.

Study subjects were made to sit comfortably in the dental chair with lumbar and thoracic spine well­supported by
the back of the chair. Shoulder girdle was stabilized by the belt strapped around the dental chair. Supine position
was attained by making the subject lay down on his back in the horizontal position with dental chair parallel to the
floor. Upright position and 30° head flexure were standardized with the goniometer by following method. For alert
feeding position, centre of the goniometer was positioned over the external auditory meatus and proximal arm was
held perpendicular to the floor. The distal arm of Goniometer was aligned to base of nares. The subject was asked
to flex the head to 30°, the goniometer used to ensure 30° flexion by measuring angle between proximal and distal
arms [Figure 1]. Due care was taken not to move the proximal arm during the head movements.

Figure 1
Clinical procedure to measure the 30° flexion

For the upright sitting position, the external auditory meatus was aligned over the shoulder joint. The Patient was
requested to occlude over the tongue depressor with the part of it extended outside the mouth. The extended part of
the tongue depressor was aligned to be parallel to the floor. Goniometer measurement at 90° was selected [Figure 2
]. All the head posture goniometer measurements were done by two researchers, including corresponding author.
All the measurements were done under the guidance of the principal author to standardize the goniometer
measurements.

Figure 2
Goniometer to standardize the upright head position

Occlusion an evaluation 3/7

T scan III (Tekscan Inc., South Boston, USA) was utilized for dynamic occlusal contact evaluation for all three
head postures. T scan provides the quantification of occlusal force and a sequence of occlusal contact, a distinct
advantage over the conventional occlusal evaluation by articulating paper. All the occlusion evaluation procedures
were executed by one researcher under the guidance of the first author.

Occlusion evaluation was initiated after determining the dental arch dimension and intra­oral sensor calibration.
Central incisor width was measured with a digital caliper to determine the dental arch dimension. Ideal sensitivity
for intra­oral sensor was identified by adjusting the high force­pink areas of contact for a maximum of three
graphical displays during trial bite on the sensors. Subjects were guided to centric relation (CR) by the Dawson
bimanual method. During occlusal evaluation, the operator guided the mandible to CR and assistant held the
articulating ribbon forceps intra­orally.

CR mode was selected in the T­scan III toolbar to provide adequate time length and recording sensitivity during CR
recording. CR recording provides information on sequential ordering of tooth contacts from an initial tooth contact
in CR up to maximum intercuspation. After completion of CR recording other dynamic occlusal contacts such as
left lateral, right lateral and protrusive movements were also recorded sequentially. Three successive recordings

http://www.st­va.ncbi.nlm.nih.gov/pmc/articles/PMC4160681/