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5/29/2016 Influence of Functional Head Postures on the Dynamic Functional Occlusal Parameters
observed in disclusion time <0.5 s. The prolonged disclusion time is also reported to be the etiological factor for
myofunctional pain dysfunction syndrome.[15] Disclusion time during supine position was 0.872 (0.372), 0.862
(0.378), 1.051 (0.472) s for left lateral, right lateral and protrusive disclusion. The alert feeding position had a
disclusion time of 0.831 (0.369), 0.274 (0.345) and 0.948 (0.451) s for similar mandibular movements. 0.629
(0.290), 0.621 (0.274), 0.696 (0.306) s were required for the disclusion during upright head posture. The
statistically significant (P < 0.5) differences were observed at disclusion time among all three head postures.
The occlusion time is the time elapsed between the initial contacts to the maximum static intercuspation of teeth.
This time ideally is as short as possible, longer occlusion time is detrimental in nature to the masticatory system.[16]
According to the results of the study, there were significant changes were found in occlusion time and disclusion
times among different head postures. Occlusion time was longest in supine head position 10.366 (0.484) s, while
alert feeding position had the least occlusion time of 0.997 (0.429) s. The mandible is located 24 mm below the
maximum intercuspation in upright head posture, while during head flexion or extension result in associated
elevator muscle contraction. The change in mandibular postural position might be the cause of changes in occlusion
and disclusion time.
The center of occlusion indicates the balance in occlusion. Studies indicate the balance of the force in the center of
the arch bilaterally and Anteroposteriorly in the region on the first molar. Studies have[17] demonstrated the
asymmetry of force is higher in the patient with TMD disorders than the normal subjects. Hence, both centers of
occlusion and asymmetry of occlusion are considered as important diagnostic criteria. The results of the study
showed the Asymmetry of force was observed more in the supine position compared other head postures.
Within the limitation of the Study, it can be concluded that there is a strong correlation between head postures and
dynamic occlual contacts. The dentists should consider evaluating occlusion in functional head postures, rather than
only in a supine head position or upright head posture. The dynamic tooth contact during functional head posture is
to be evaluated, corrected and monitored for the longterm success of restorations.
Conclusion Go to:
The dynamic occlusal contacts during the functional head postures should be accounted during the diagnostic and
therapeutic procedures. This study demonstrated the change in the initial contact between supine, upright and active
feeding head postures. The occlusion and disclusion times were also significantly different in all head postures
evaluated. The asymmetry of force was found to be highest in the supine position. During the management of
occlusion during the restorative procedures and TMD these changes should ideally be taken into consideration.
Acknowledgment Go to:
The study was selffinanced; the authors would like to thank King Khalid University for providing the facility to
evaluate the participants.
Footnotes Go to:
Source of Support: Nil.
Conflict of Interest: None declared.
References Go to:
1. Kerstein RB, Radke J. Masseter and temporalis excursive hyperactivity decreased by measured anterior guidance
development. Cranio. 2012;30:243–54. [PubMed]
2. Reinhardt R, Tremel T, Wehrbein H, Reinhardt W. The unilateral chewing phenomenon, occlusion, and TMD.
Cranio. 2006;24:166–70. [PubMed]
3. Weon JH, Oh JS, Cynn HS, Kim YW, Kwon OY, Yi CH. Influence of forward head posture on scapular
upward rotators during isometric shoulder flexion. J Bodyw Mov Ther. 2010;14:367–74. [PubMed]
http://www.stva.ncbi.nlm.nih.gov/pmc/articles/PMC4160681/ 6/7
