TITLE:
Influence of Voluntary Clenching on Spinal Range of Motion Depends on Occlusal Contact State
AUTHORS:
Mutsumi Takahashi, Yogetsu Bando, Takuya Fukui
KEYWORDS:
Occlusal Contact State, Clenching, Spinal Range of Motion, Trunk Flexion
JOURNAL NAME:
Advances in Physical Education,
Vol.13 No.4,
November
21,
2023
ABSTRACT: Purpose: The aim of this study was to clarify the effects of voluntary moderate
clenching on the range of motion of the spine depending on the occlusal contact state. Method: Participants were 46
healthy men with no missing teeth except for wisdom teeth, and no
medical history of musculoskeletal neurological or orthopedic surgery. Using a
pressure-sensitive film, the participants were
divided into those with a lateral difference in occlusal contact area of less than 10% (good occlusal balance group) and those with 10% or more (occlusal imbalance group). A spinal shape analyzer was
used to measure the curvature of the
spine in the static standing posture and the standing forward bending
posture. The evaluation indices were thoracic kyphosis angle (TKA), lumbar
lordosis angle (LLA), sacral inclination angle (SSA), and spinal inclination
angle (SIA), and the range of motion for each alignment configured on the
analyzer software. Two measurement conditions were compared: mandibular resting position (RP) and voluntary 50%
maximal clenching (50% MVC) in the
intercuspal position. Differences in range of motion for each spinal align- ment due to occlusal balance and
clenching were analyzed with a split-plot design. Results: LLA,
SSA, and SIA showed significant differences in occlusal balance and clenching
factors. In the good occlusal balance group, LLA, SSA, and SIA were
significantly lower in 50% MVC condition than in RP condition. In the occlusal imbalance group, there was no
difference between the presence or absence of clenching in any spinal
alignment. Conclusion: As a result of this study, it was clarified that
the effect of clenching on the range of motion
of the spine during trunk flexion differs depending on the occlusal
contact state. In other words, it was suggested that voluntary clenching
restricts trunk flexion in participants with good occlusal balance.