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5/29/2016 Influence of Functional Head Postures on the Dynamic Functional Occlusal Parameters
were performed on all movement to validate the tooth contacts. The occlusion and disclusion time were calculated
by observing relative forcetime graph. The occlusion time was determined by recording the time lapse from initial
tooth contact to maximum intercupation. The disclusion time was calculated at the time required for complete
disoccluion from maximum intercuspation in excursive movements. Center of occlusion is shown in T scan graph,
centralization of the force is calculated by measuring the distance from this point to the center of the graph.
Asymetry of the force was calculated by the following formula:
Statisical analysis
The data obtained was subjected to statistical analysis by SPSS 19 software (Chicago, IL, USA). Repeated
measures of ANOVA was utilized for statistical comparison in the variation of occlusal contacts during different
head postures.
Ethical consideration
The research ethics committee at college of dentistry, King Khalid University approved the research. The objective
and research methodology were explained to all participants and their written consent was obtained before the
inclusion in the study.
Results Go to:
Occlusion and disocclusion time
Table 1 demonstrates the mean values, oneway ANOVA analysis of occlusion and disclusion times during
different head postures.
Table 1
Illustrate the mean values of clusion and disclusion times during different
head postures
The occlusion time was 1.366 (0.484) s for the subjects during the supine head posture and 1.226 (0.562) s while
the head was in an upright position. The occlusion time was comparatively less (0.997) during the alert feeding
head position.
The disclusion time required for right lateral movement was 0.872 (0.372), 0.629 (0.290), 0.831 (0.369) s during
supine, upright and 30° forward head postures. The corresponding values for a left lateral diclusion time were
0.862 (0.378) s for supine position. The upright head posture and 30° forward head postures required 0.621
(0.274), 0.274 (0.345) s respectively. The protrusive disclusion time also had similar diclusion time patterns. 1.051
(0.472) s for supine head posture, 0.696 (0.306) s during upright posture and 30° forward head posture had 0.948
(0.451) s.
As shown in the Table 1, there was a significant change in occlusion and disclusion time at different head posture.
Hence, these values were subjected to repeated measures of ANOVA to identify the existence of statistically
significant variation in occlusal parameters during different head postures. When Mauchley's test of Sphericity was
significant, a Greenhouse Geisser correction of degrees of freedom was used for testing the effect within the
subjects. Table 2 presents the GreenhouseGeisser values for all groups. The analysis showed F values of 18.513,
20.227 and 37.831 for right lateral, left lateral and protrusive disclusion times respectively. P values for all the
groups was <0.001. F value for occlusion time was 20.390 with P < 0.05. The result indicated the presence of
statistically significant variation between occlusal parameters in different head postures evaluated in the study.
Table 2 4/7
http://www.stva.ncbi.nlm.nih.gov/pmc/articles/PMC4160681/