• Journal of Oral Medicine and Pain
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• v.15 no.1
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• pp.117-124
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• 1991

The purpose of his study was to investigate the variations of occlusal contact pattern according to chewing side preference. The author selected 59 dental students (mean age 23.6 years) who had no signs and symptoms of masticatory disorders and divided into two groups, that is, bilateral chewing side group and unilateral chewing side group, respectively. For recording, T-Scan System(Teksan Inc., USA) was used and the recorded occlusal contacts were examined as to the number of occlusal contacts, points distribution in dental arch, time sequence and force snapshot. The obtained results were as follow s: 1. Total number of occlusal contacts were more in unilateral chewing side group and there were significant difference in number between right and left side or between chewing and less-chewing side in all two groups. 2. All items related to time sequence showed no statistical significant difference between two groups in any case. 3. Unilateral chewing side group had more occlusal contact force than bilateral group, especially in chewing side. From the above finding, the author considered that there was occlusal unbalance in unilateral chewing side group. 4. Chewing side preference would possibly have more effects on the occurrence rate of anterior tooth contact that the rate of prolonged their contact but proved.

• Journal of International Academy of Physical Therapy Research
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• v.11 no.1
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• pp.1954-1959
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• 2020

Background: Due to aging, blood flow rate decreases, also posture and chewing habit may be changed. Objective: To identify that changes in blood velocity in the common carotid arteries (CCAs) in old persons with unilateral chewing habit (UCH) and forward head posture (FHP) in the elderly. Design: An observational cross-sectional study. Methods: Chewing habits, FHP, and CCAs velocities were assessed in 85 elderly subjects. Chewing habits were measured by visual observation. CCAs measured the peak systolic velocity (PSV), end-diastolic velocity (EDV), minimum diastolic velocity, and resistivity index. The subjects were divided into UCH and bilateral chewing habit groups depending on chewing habit. The subjects were also divided into >49 degrees and <49 degrees for comparison of blood flow between the left and right CCAs. Results: In the UCH, the chewing side had significantly higher EDV (P=.003), PSV (P=.023) than the non-chewing side. There was no significant difference in velocity between the CCAs in the FHP. Conclusion: This study shows that the blood flow velocity of the chewing side of UCH was higher, and unilateral chewing affects the CCAs velocity and thus highlight the importance of chewing habit in the elderly than head posture.

• The korean journal of orthodontics
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• v.25 no.3 s.50
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• pp.311-321
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• 1995

This study was undertaken to investigate the distribution of the chewing side preference and variations in the maximum bite force and facial morphology according to chewing side preference since unilateral chewing may cause morphologic and functional anomalies. 50 dental students who had no signs or symptoms of masticatory system and Angle's Class I relationship in posterior segments were selected, and divided into two groups, that is, 25 in bilateral chewing group(19 male and 6 female) and 25 in unilateral chewing group(10 male and 15 female). Maximum bite force was estimated ana posteroanterior cephalogram were measured ana statistically analyzed. The results were as follows : 1. Their were more students with bilateral chewing side preference($68\%$) and unilateral chewing side group consisted of right side preference($68\%$) and left side preference($32\%$). 2. There was no significant difference in the strength of max. bite force between the right and left side in bilateral chewing group. The bite force of the chewing side nab greater in the unilateral chewing group but less in the non-chewing side compared to those of bilateral chewing group with Bo significant difference. Max. bite force of chewing side was greater than that of non-chewing side in the unilateral chewing group(Female p<0.05). Max. bite force of males was about twice in that of females in both groups(p<0.05). Max. bite force of chewing side of the unilateral chewing group was similar to that of the bilateral chewing group, but that of non-chewing side was less than that of the bilateral chewing group. 3. In comparison of the facial morphology, there was no statistically significant difference in the size between the right and left side of the bilateral chewing group and between chewing and non-chewing side of the unilateral chewing group.

• The Journal of Korean Academy of Prosthodontics
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• v.40 no.6
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• pp.577-589
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• 2002

There are several variations in normal mastication. In them, unilateral mastication is chewing, predominantly on a preferred side of the dentition and hardly on e non-preferred side. Continual unilateral mastication may alter the coordination of masticatory muscles. Although they studied about these EMG of masticatory muscles, there were no information about characteristics of masticatory muscle activity in unilateral mastication. Therefore, In this study, we investigated the activity of the masseter and anterior temporal muscles during rest, clenching in maximum intercuspation and gum chewing in habitually unilateral mastication group compared with normal group and tried to know effects of continual unilateral mastication on activity of masticatory muscles. The results of this study were as follows 1. In electromyographic activity during rest, in bilateral mastication group pattern of muscle activity of right and left side was symmetrical. But, in unilateral mastication group, records of anterior part of temporal muscle was higher than that of bilateral mastication group (p<.01) and patterns of muscle activity of right and left side in both muscle were asymmetrical.(p<.05) 2. In electromyographic activity during clenching in maximum intercuspation, records of superficial part of masseter muscle were higher than anterior part of temporal muscle in both group. Muscle activity of temporal muscle in unilateral mastication group was a little higher han bilateral mastication group and asymmetry of activity pattern in temporal and masseter muscle was shown but these differences were not statistically significant. (p<.05) 3. In electromyographic activity during gum chewing, temporal muscle was activated earlier than masseter muscle and maximum bite force is derived from masseter muscle in both group. In unilateral mastication group, electromyographic activity of masseter and temporal muscle of preferred chewing side, regardless of right or left side chewing, was higher than that of bilateral mastication group and especially, difference in masseter muscle was statistically significant. (p<.01) Based on the above results, our study suggested that recording of masticatory muscle activity will be helpful in the effective diagnosis and treatment of some types of the parafunctional habits.

• The Journal of Korean Academy of Prosthodontics
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• v.32 no.1
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• pp.103-119
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• 1994

The purpose of this study was to evaluate the mandibular movements of TMD patients comparing to normal persons. Sirognathograph was used to measure five parameters of mandibular movements of twenty normal persons and eight TMD patients. Five parameters were (1) Maximum opening during maximum opening and closing, (2) Mean velocity during maximum opening and closing, (3) Maximum opening during unilateral chewing, (4) Mean velocity during unilateral chewing, (5) Consistency of mandibular movement during unilateral chewing. Based on above results, new Mandibular Movement Index(M.M.I.) was formulated and compared to Helkimo's Clinical Dysfunction Index by measuring two indices before treatment and 2 weeks, 4 weeks, 6 weeks, 8 weeks after treatment. The conclusions were as follows: 1, The amounts of maximum opening and mean velocity during maximum opening and closing of TMD patients were less than those of normal persons(p<0.01). 2. The amounts of maximum opening and mean velocity during unilateral chewing of TMD patients were less than those of normal persons(p<0.05) (P<0.01). 3. Although TMD patients showed limited mandibular movements during unilateral chewing, the consistency of mandibular movements was better than that of normal persons(p<0.05). 4. Both mandibular movement index and Helkimo's Clinical Dysfunction Index, were useful in diagnosing TMD patients.

• Journal of Oral Medicine and Pain
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• v.20 no.2
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• pp.291-306
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• 1995

Mandibular movement is composed of border movement and functional movement. Border movement such as maximal mouth opening, hinge opening ad lateral eccentric movement has good reproducibility, but functional movement such as chewing, swallowing and speech has also reproducibility. Especially for chewing movement, individual reproducibility has been confirmed by many studies. Study of chewing pattern is still in controversy. In new approach for raising the diagnostic value, numeric parameters and morphologic characteristics could be used for evaluation of chewing pattern. This study was performed to investigate the differences between chewing pattern in controls and in patients with temporomandibular disorders. Sixty-three patients with temporomandibular disorders participated in this study, and they were divided into unilaterally affected subjects or bilaterally affected subjects. Then unilaterally affected subjects were classified into closed lock group, disk displacement with reduction group, and degenerative joint disease group. For recording of chewing pattern, subjects were asked to chew one piece of presoftened chewing gum on both sides, and the chewing movement was recorded with the Electrognatho- Graphy(Bio-Research Associates Inc., U.S.A.). Tooth contact pattern for occlusal stability (Total left-right statistics )was also recorded with T-Scan(Tekscan Co., U.S.A.). The dta related to chewing pattern and total left-right statistics were statistically analyzed by SAS/stat program. The obtained results were as follows : 1. In patient group, mean value of A-P distance and the ratio of A-P distance to vertical distance were larger than control group, but the value of lateral distance in affected side and the closing velocity in unaffected side were smaller than that of control group, respectively. 2. In case of unilateral affected patients, chewing pattern of other side had tendency to restricted movement and slow velocity in closed lock group or degenerative joint disease group than control group or disk displacement with reduction group. 3. In bilateral degenerative joint disease patients, contralateral side had tendency to large range of motion and slow chewing velocity than preferred chewing side. 4. The patients with restricted mouth opening below than 35mm had higher value of total left-right statistics than patient group mouth opening above 35mm. Also closed lock group had higher total left-right statistics than disk displacement with reduction group, degenerative joint disease group and control group. 5. There was some difference in morphologic characteristics of chewing pattern between in control group and in affected side of unilateral patient group, but no difference between control group and unaffected side of unilateral patient group. 6. There were positive correlations between vertical distance and A-P distance, between vertical distance and chewing velocity, between A-P distance and chewing velocity, and between opening velocity and closing velocity in unilateral affected patients.

• Journal of Oral Medicine and Pain
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• v.31 no.3
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• pp.245-254
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• 2006

While orofacial pain or various dental factors are generally considered as the primary cause of unilateral chewing tendency, there exist several studies indicating that dental factors did not affect the preferred chewing side. The aim of this study was to examine difference of occlusal scheme between the subjects with and without chewing side preference. The difference between the chewing and non-chewing sides in the unilateral chewing group was investigated as well. Computerized, T-Scan II system was used for occlusal analysis. 20 subjects for the unilateral chewing group (mean age of $25.25{\pm}2.84$ years) and 20 subjects for the bilateral chewing group (mean age of $27.00{\pm}5.07$ years) were selected by a questionnaire on presence or absence of chewing side preference and those with occlusal problem or pain and/or dysfunction of jaw were excluded. T-Scan recordings were obtained during maximum intercuspation and excursion movement. The number of contact points, relative occlusal force ratio between right and left sides, tooth sliding area and elapsed time throughout the maximum intercuspation were calculated. Elapsed time for excursion was also investigated. The results of this study shows that the unilateral chewing group had the smaller average tooth contact areas compared with those of the bilateral group (p<0.005). In the unilateral chewing group, the contact areas of non-chewing side are smaller than those of chewing side (p<0.005). The contact areas on their preferred sides were not significantly different with those of right or left side of the subjects without chewing side preference. There was no significant difference in the elapsed time during maximum intercuspation and lateral excursion, the sliding areas and relative of right-to-left occlusal force ratio between the two groups. From the results of this study, it is likely that individuals prefer chewing on the side with more contact areas for efficient chewing.

• The Journal of Korean Academy of Prosthodontics
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• v.29 no.2
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• pp.285-294
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• 1991

The human temporomandibular joint as a ginglymoarthrodial one has much in common with the other synovial joints of the body, but it does possess an unique charachteristic in that it must accomodate the various occlusal relations of dentition during an end point of closure. For that reason, the movement of the condyle in the temporomandibular joint is susceptible to influences from the nature of occlusion. Undue loading to the temporomandibular joint can be applied on the occasion of premature contacts in centric relation, balancing side interferences, change of occlusal surfaces due to excessive attrition, loss of tooth. Such occlusal disharmonies in association with the systemic and emotional factors may give rise to the temporomandibular disorder. On the other hand, the changes of occlusal patterns in the growing body can also have an effect on the growth of the temporomandibular joint through the alterations of functional stresses. The purpose of this study was to observe histopathologic response of the temporomandibular joint in unilateral chewing on one side exclusively for 10 months. Three dogs showing normal masticatory function were chosen. One dog aged about 12 months was for control, two dogs for experimental specimens were about 12 and 18 months old respectively. For chewing on the left side only, unilateral lower right premolar and molar were extracted in two experimental specimens. And then three dogs were sacrificed 10 months later. Frontal histologic sectioning of joints were done for the observation of the effects of one-side chewing. 24 specimens from three dogs were obtained and fixed in 10% formalin and routinly processed with H-E staining for histologic examination. The light microscopic findings were interpretated as follows: 1. Experimental specimen 1 aged about 22 months: In comparison with control and right non-chewing side, the proliferative and hypertrophic zone were increased at the mesial and lateral part of left chewing side condyle. There was no change of the articular tissue of temporal bone. 2. Experimental specimen 2 aged about 28 months: The articular tissues of adult joint were observed. The differences between the chewing and non-chewing side were not seen in the articular tissues of condyle and temporal bone.

• Journal of Oral Medicine and Pain
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• v.21 no.2
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• pp.265-277
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• 1996

The aim of this study was to investigate the electromyographic(EMG) activity of masticatory and cervical muscles according to chewing pattern in coronal plane during gum chewing. 70 patients with temporomandibular disorders and 30 dental students without any signs and symptoms of the disorders participated in this study. We measured the activity of masseter (MM), anterior temporalis(TA), sternocleidomastoideus(SCM) and trapezius muscle and recorded the chewing patterns using Biopak system synchronously. Chewing pattern was classified into S- or L-pattern by the midline opening path and short or long type by the lateral distance from midline. Obtained data were analyzed with SAS/STAT Program. The obtained results were as follows : 1. Generally, there was tended to be higher activity in the control group than in the patients group. 2. When comparing EMG activity according to preferred side, the muscle activity was tended to higher on the preferred chewing side than on the contralateral side. However, this difference is insignificant statistically 3. In unilateral affected patients, there was no difference in muscle activity between affected chewing side and unaffected chewing side except for the EMG of the temporalis anterior muscle. 4. Despite the varietal in each of the following variables, there mere no differences in EMG activity during gum chewing: chewing pattern in coronal plane and lateral distance of chewing. 5. The activity of SCM in chewing side was higher than that in contralateral side (p<0.001), but there was no difference in trapezius muscle. 6. In all of the control group, there was appeared L-chewing pattern than not involved the midline during preferred side chewing.

• The korean journal of orthodontics
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• v.44 no.3
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• pp.143-153
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• 2014

An 8-years old boy with facial asymmetry and unilateral posterior crossbite on the left side received orthopedic and orthodontic treatment. During the first phase of treatment, the narrow maxillary arch was expanded using an acrylic plate. Then, the acrylic plate was used as a bite block with occlusal indentations from the construction bite that was obtained with the incisors in a coincident dental midline. After the position of the mandible was stabilized, the second phase of orthodontic treatment was initiated using fixed appliances for detailing of the occlusion. Skeletal symmetry, ideal occlusion, and coincident dental midlines were thus achieved. Functionally, occlusal force balance and masticatory muscle activity were improved, and the chewing patterns were normalized.