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Examination of the relationship between mandibular position and body posture.(PHYSICAL THERAPY)(Clinical report).

CRANIO: The Journal of Craniomandibular Practice 25.4 (Oct 2007): p.237(13). (5897 words)
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Author(s): Kiwamu Sakaguchi, Noshir R. Mehta, Emad F. Abdallah, Albert G. Forgione, Hiroshi Hirayama, Takao Kawasaki and Atsuro Yokoyama.
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ABSTRACT: The purpose of this study was to evaluate the effect of changing mandibular position on body posture and reciprocally, body posture on mandibular position. Forty-five (45) asymptomatic subjects (24 males and 21 females, ages 21-53 years, mean age 30.7 years) were included in this study and randomly assigned to one of two groups, based on the table of random numbers. The only difference between group I and group II was the sequence of the testing. The MatScan (Tekscan, Inc., South Boston, MA) system was used to measure the result of changes in body posture (center of foot pressure: COP) while subjects maintained the following 5 mandibular positions: 1) rest position, 2) centric occlusion, 3) clinically midlined jaw position with the labial frena aligned, 4) a placebo wax appliance, worn around the labial surfaces of the teeth and 5) right eccentric mandibular position. The T-Scan II (Tekscan, Inc., South Boston, MA) system was used to analyze occlusal force distribution in two postural positions, with and without a heel lift under the right foot. Total trajectory length of COP in centric occlusion was shorter than in the rest position (p<0.05). COP area in right eccentric mandibular position was larger than in centric occlusion (p<0.05). When subjects used a heel lift under the right foot, occlusal forces shifted to the right side compared to no heel lift (p<0.01). Based on these findings, it was concluded that changing mandibular position affected body posture. Conversely, changing body posture affected mandibular position.

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Harmony and balance between form and function in the vital organs of a living body are essential for the maintenance of a healthy condition. This concept applies to the relationship between the stomatognathic system and the whole body. A controversy exists in the literature as to the interrelationship between mandibular position, stomatognathic function and the general health of the body. (1-6)

Patients with temporomandibular disorders (TMD) and orofacial pain may have neck, shoulder and back problems. Poor body posture is frequently observed in these patients. (5,7) It has been reported that these problems may be improved by dental treatment and physical therapy. (2, 8-10) Changes in the stomatognathic system may affect stomatognathic function as well as body posture. (1-6, 11) Researchers have investigated the relationship between head posture and mandibular position for many years. (3,6,12-14) There are reports in the literature supporting a relationship between head posture and masticatory muscle activity, (15-18) postural rest position of the mandible, (19,20) habitual pathway of jaw closure, (21) and mandibular position. (3,6,12-14,21) Although there are several studies investigating the relationship between mandibular position and body posture, most of them evaluate the effect of changing mandibular position on body posture. (1-6,11) Studies evaluating the effect of changing body posture on dental occlusion are still lacking. Quantitative research evaluating the effect of changing stomatognathic system on body posture and body posture on stomatognathic system is very important in the attempt to understand how such changes impact TMD signs and symptoms. Makofsky, et al. (22) investigated the effect of sagittal plane head-neck posture on initial tooth contacts (muscle contact position) using the T-Scan (Tekscan, Inc., South Boston, MA) system of occlusal analysis. Results indicated that below the age of 30 years, no significant relationship was demonstrated between head posture and muscle contact position. However, over the age of 30, there was an increasingly significant relationship between sagittal plane head-neck posture and initial occlusal contacts. The authors recommended that management of occlusally related problems, i.e., TMD, include an assessment of the craniovertebral region especially in patients over the age of 30 years.



The purpose of this study was to quantitatively evaluate the effect of changing mandibular position on body posture and reciprocally, body posture on mandibular position.

Materials and Methods

Fifty (50) asymptomatic subjects from the students, faculty, and staff of Tufts University School of Dental Medicine (Boston, MA) volunteered for this study. Forty-five (45) subjects (24 males and 21 females, ages 21-53 years, mean age 30.7 years) were included in this study, while five were excluded because of failure to meet the inclusionary criteria. Inclusionary criteria were: 1. no history of recent trauma; 2. in healthy condition; 3. asymptomatic for disturbance in the masticatory function (for groups I and II); 4. asymptomatic for temporo-mandibular disorders and orofacial pain (for groups I and II); and 5. age between 21-41 years. Exclusionary criteria included: 1. history of head and neck and/or back problems: 2. history of TMD and orofacial pain signs and symptoms: 3. history of orthopedic and/or otolaryngologic problems affecting body balance: 4. presence of five or more permanent dental restorations (i.e., crowns, bridges, implants and/or removable prosthetics); and 5. presence of loose or broken teeth, fillings or crowns which could be further damaged during the course of the study.



Testing Equipment

The MatScan system (Tekscan Inc., Boston, MA): This instrument provided a dynamic evaluation of body posture. The system measured weight distribution and changes in the position of the center of foot pressure (COP) on a footplate during a standard measuring period. (13, 6,11,20) COP is the center of vertical force acting on the support surface. It indicates gravity shifts in anteroposterior and lateral directions. (2) This system consisted of a large footplate sensor and a personal computer for data analysis (Figure 1). The sensor was placed between the plantar surfaces of the feet and a rigid ground. The footplate consisted of several layers of electrically conductive ink rows and columns on a polyester film sheet. The measurement area was 432 mm x 368 mm, including rows and columns forming an X-Y grid of 2288 sensing elements (spatial resolution is 1.4 sensors/[cm.sup.2]). The sensing pressure range was 1-150 PSI (Figure 2). Information collected by the sensor was ted to a computer. Data were processed by the dedicated software, I-Scan software (Tekscan Inc., Boston, MA), which provided graphic and numerical output regarding timing, location, and relative amount of pressure applied to the sensor. When a subject stood on the footplate, pressure at the bottom of both feet was measured in equalized four-quadrant sections (1: left anterior, 2: right anterior, 3: left posterior, 4: right posterior) (Figure 3). The percentage of each section compared with the entire weight was calculated. In this study, a sampling rate of 40 Hz (40 frames per second) was used.



A preliminary test was conducted to check the time and spatial signal, and the relative amount of pressure exerted by objects of standardized mass, size, and shape. The system was found reliable for time and spatial characteristics.



The T-Scan II computerized occlusal analysis system (Tekscan Inc., Boston, MA): This device was used to analyze the center of occlusal force (COF) and the occlusal force distribution during a standard measuring period (Figure 4). To analyze the distribution of occlusal force, the dental arch was divided into equalized fourquadrant sections (1: left anterior, 2: right anterior, 3: left posterior, 4: right posterior) (Figure 5). The percentage of each section compared with the entire occlusal force was calculated, utilizing the I-scan software. A one/hundredth (.01) second real-time occlusal contact recording and .01 second incremental playback of the tooth contact timing data illustrated the exact order of tooth contacts, as well as their force content. Real-time recording was accomplished by measuring the recorded tooth contacts at a rate of 80 Hz. (23)



Coprwax Bite Wafers (Heraeus Kulzer, Inc., Armonk, NY) (Figure 6): Wax registrations were used to support mandibular positions and to provide a placebo condition.



Cork Heel Lift (G & W Heel Lift, Inc., Cuba, MO) (Figure 7): A thick insole (9 mm thick) was placed under the right heel to disturb balance of body posture.

Definitions

Rest position (1): Teeth slightly apart and masticatory muscles in a relaxed non-contractile condition.

Corrected mandibular position (CMP): Clinically midlined jaw position with the maxillary and mandibular labial frena aligned, and an anterior overbite covering 20% of the mandibular anterior teeth and an anterior overjet of 1.0 mm.

Placebo position (PP): In centric occlusion, a softened bite registration wax wafer was molded around the labial surfaces of the teeth. The wafer did not cover the occlusal surfaces and did not interfere with maximum intercuspation of the upper and lower teeth.

Right eccentric mandibular position (REMP): The upper and lower right canines in an edge to edge position.

Natural standing--centric occlusion (NS-CO): Centric occlusion, while the subject stood in a natural standing posture without using a heel lift.

Heel lift--centric occlusion (HL-CO): Centric occlusion, while the subject stood in a natural standing posture with a heel lift under the right foot.

Testing Procedure

This study was conducted in a randomized single blind fashion as follows (Table 1):

* Each subject was randomly assigned to one of two groups, based on the table of random numbers. The only difference between group I and group II was the sequence of the testing. In all other respects, the individual trials did not differ. Subjects completed a standard TMD symptom form (Figure 8) and Health questionnaire. An examination of the head and neck area for pain was completed by the investigator. If the subject met the inclusionary criteria, he/she was introduced to the next step.


* Three wax registrations were fitted. The subject was guided to bite slowly and gently into a softened wax registration. The wax was inserted between the maxillary and mandibular dental arches, in a CMP as determined by the investigator. The subject was then guided to bite the same material as above in a REMP. Finally, the subject was requested to bite in centric occlusion and a softened wax wafer was molded around the maxillary and mandibular teeth without interfering with occlusion (PP). Each of the three wax registrations was placed in a separate box, marked as either A, B or C. Subjects were blinded as to which condition was being tested.



* For all testing, the subject was asked to remove his/her shoes. To assist in obtaining natural standing posture, each subject was asked to look directly into the reflected image of his/her eyes one and 1/2 meters away with arms hanging free (Figure 1). MatScan section: To evaluate the effect of change in mandibular position on body posture, the MatScan data were recorded while the subject maintained the five mandibular positions (centric occlusion, RP, CMP, PP, and REMP). Testing was recorded for ten seconds while the subject stood on the sensor and maintained a stable head and body posture. The investigator performed this testing as follows: First, the investigator recorded the MatScan data with the subject biting in centric occlusion and repeated it with the subject's teeth slightly apart. (7) Next, the subject was requested to put the wax registration (box A) in his/her mouth and bite into it, and the data were recorded. The subject was requested to take the wax registration out and walk around the room once before the next measurement was initiated. The above procedure was repeated for the wax registrations in boxes B and C. Next, while the subject maintained a natural standing position on the MatScan footplate, a thick insole was placed under the right heel. The subject then bit down in centric occlusion and the MatScan data for HL-CO were recorded.

T-Scan section: To evaluate the effect of change in body posture on mandibular position, the data of two postural positions, with and without a heel lift under the right foot, were recorded using the T-Scan system. The T-Scan sensor (Figure 4) was placed in the subject's mouth. The subject was requested to tap several times on the sensor in order to make indentations in the T-Scan sensor. The subject was then requested to bite slowly and gently into the T-Scan sensor up to his/her centric occlusion (NS-CO). Next, a thick heel lift was placed under the right foot, and the investigator recorded the T-Scan data for HL-CO. Subjects were requested to walk around between trials in order to prevent fatigue, and to avoid postural contractions of muscles.

Parameters

The total trajectory length of COP/COF and the COP/COF area: Each trial of the MatScan system was recorded in 400 frames for ten seconds. The 2-dimensional coordinates of COP were acquired for every frame. The effective distance of COP between one frame and the next frame was calculated, based on the pitch of the sensor sheet in each trial. Total trajectory length of COP (mm) for each trial was then calculated by summing all of the effective distances of COP between 400 consecutive frames. The above calculation was carried out for the total trajectory length of COF for the T-Scan system data, from initial tooth contact to centric occlusion. COP area is the rectangular area of the total trajectory of 400 COPs. The same calculation was carried out for the COF area. The calculation for the COP/COF area was as follows:

COP/COF area ([mm.sup.2]) = maximum anteroposterior amplitude width of COP/COF modification (mm) X maximum lateral amplitude width of COP/COF modification (mm).

These parameters were used to evaluate the stability of body posture/mandibular position. The shorter the total trajectory length of COP/COF and the smaller the COP/COF area was, the more stable was the body posture/mandibular position. Conversely, the longer the total trajectory length of COP/COF was and the larger COP/ COF area was, the less stable was the body posture/mandibular position. Moreover, COP/COF area indicates the magnitude of the sway of body posture and the shifting of mandibular position anteroposteriorly and laterally.

The lateral and anteroposterior weight distribution and occlusal force distribution: A four-quadrant weight distribution value in % was measured for every frame in each trial. First, the lateral weight distribution and the anteroposterior weight distribution values for each frame were calculated. Next, the mean value of the sum of all lateral weight distribution values in each trial was calculated (LWD). The same calculation was carried out for the anteroposterior weight distribution value (AWD). The lateral occlusal force distribution (LOD) and the anteroposterior occlusal force distribution (AOD) values were measured for the T-Scan system data. These values were obtained in the same manner as the LWD and AWD respectively. The lateral weight distribution (LWD) values were calculated as follows:

LWD/LOD(%) = 50 - (the right-anterior value + the right posterior value);

AWD/AOD(%) = 50 - (the right-posterior value + the left-posterior value).

These parameters were used to evaluate the balance of body posture and occlusal force. When the weight distribution and occlusal force distribution were equal bilaterally, LWD/LOD was zero. When it shifted to the right side, LWD/LOD was negative. When it shifted to the left side, LWD/LOD was positive. When it was equal anteroposteriorly, AWD/AOD was zero. When it shifted to the anterior side, AWD/AOD was positive. When it shifted to the posterior side, AWD/AOD was negative.

Analysis

For the MatScan section, the total trajectory length of COP, COP area, LWD and AWD in centric occlusion was compared to those in the other four mandibular positions (RP, CMP, PP, and REMP), respectively, in order to evaluate whether changes in mandibular position affected body posture. The effect of using a heel lift under the right foot on body posture was also evaluated. For all comparisons, the Friedman two-way ANOVA and the Dunn's multiple comparison analysis were used. For the T-Scan section, the total trajectory length of COF, COF area, LOD and AOD was compared with and without a heel lift under the right foot in order to evaluate whether changes in body posture affected mandibular position. In analyses of the T-Scan data, centric occlusion was defined as the mandibular position, where occlusal forces reached 90% of its maximum capacity in a relative force-time graph. (25-27) The relative force-time graph used in this analysis was programmed in the T-Scan software. The Wilcoxon matched pairs sign-ranks test was used to compare the impact of the heel lift versus no heel lift for total trajectory length of COF and COF area, LOD and AOD. Occlusal force distribution in LOD and AOD were analyzed for initial tooth contact (the first five frames) and centric occlusion.

Results

The results of the comparisons (median values) in total trajectory length of COP between centric occlusion and the other mandibular positions are shown in Figure 9. Only total trajectory length of COP in centric occlusion was significantly shorter than it was in the rest position (p<0.05). All other comparisons were not significant.

Figure 10 shows that median COP areas in both the placebo position (p<0.01) and right eccentric mandibular position (p<0.05) were significantly larger than in centric occlusion. No significant differences were found in COP area between centric occlusion and the other two mandibular positions.

The results of the comparisons (median values) in the lateral and anteroposterior weight distribution between centric occlusion and the other mandibular and postural positions are shown in Figures 11 and 12 respectively. There were no significant differences in the distribution of foot pressure by changing mandibular positions compared to that in centric occlusion anteroposteriorly and laterally. However, when subjects used a heel lift under the right foot and bit down in centric occlusion, the foot pressure shifted to the right side and backwards (p<0.01) (Figures 11 and 12).

The results of the comparisons (median values) in total trajectory length of COF and COF area from an initial tooth contact through centric occlusion between NS-CO and HL-CO are shown in Figures 13 and 14 respectively. No significant differences were found in total trajectory length of COF and COF area between NS-CO and HLCO.

The results of the comparisons (median values) in LOD and AOD on initial tooth contact and centric occlusion between NS-CO and HL-CO are shown in Figures 15-18. When subjects used a heel lift under the right side, occlusal force distribution shifted significantly to the right side laterally in both initial tooth contact and centric occlusion (p<0.01) (Figures 15 and 17). No significant differences were found in the anteroposterior occlusal force distribution between NS-CO and HL-CO in both initial tooth contact and centric occlusion (Figures 16 and 18).



Discussion

Results of total trajectory length of COP and COP area suggested (Figures 9 and 10) that body posture was significantly more stable when subjects bit down in centric occlusion than when they maintained their mandibles in the rest position, placebo position and right eccentric mandibular position. The sway of body posture, as measured by area, was significantly larger in placebo position and right eccentric mandibular position than when subjects bit down in centric occlusion.

Stability in head position is indispensable to the control of body posture. The anterior and posterior cervical muscles are concerned with the stability and movement of the head. (2-5,24) When posterior occlusal support is lost, the information from masticatory muscles or temporo-mandibular joint proprioceptors and periodontal ligament mechanoreceptors are altered. These changes are reported to effect cervical muscles through the trigeminal nerve. (25)

Cervical nerves C1 to C4 are primarily involved in controlling head posture, (26) and the proprioceptive inputs from the muscles and articulations of the neck are important in the maintenance of postural balance. (27) Stimulation of the vestibular system by changing head position has a descending influence on the triceps muscle of the calf and the soleus muscle, both antigravity muscles. (28)

Based on these previous reports, stability of the head is maintained through the action of the cervical area.

In a study evaluating the influence of the trigeminal system on extensor muscles of the neck in cats, lambs, and rabbits, Manni, et. al. (29) found that stretching the eye muscles can influence the unitary discharge of the extensor muscles of the neck and forelimbs. Similar responses have been reported with stimulation of the ophthalmic and maxillary branches of the trigeminal nerve. They suggested that neck responses elicited by trigeminal nerve and field stimulation can be considered as defensive reflexes. Broser, et. al. (30) reported on the effect of electrical stimulation of the face. They found that the response was not limited to facial muscles, but in fact extended to cervical muscles as well. The present results found that body posture was significantly more stable when subjects bit down in centric occlusion than when they maintained their mandibles in the rest position (Figure 9). This result suggests the following possibility: Bilateral occlusal contacts in centric occlusion caused a change bilaterally in the peripheral inputs from each organ in the stomatognathic system and resulted in acquiring both the stability of the neck and the head positions. Consequently, body posture was more stable when subjects bit down in centric occlusion compared to when they maintained their mandibles in the rest position.



It was expected that there would be no changes in body posture in the placebo position compared to that in centric occlusion. However, body posture was less stable when subjects maintained their mandibles in the placebo position compared to when they bit down in centric occlusion (Figure 10). This result suggests the following possibility: In a placebo position appliance, a softened bite registration wax wafer was used. It was molded around the labial surfaces of the teeth, provoking the mechanical stimulus for the buccal, labial gingivae, and the buccal mucosa. These may have caused changing of the afferent information through the intraoral organs. Changes in the information through the trigeminal nerve may have caused a disharmony of the neuromuscular system in the craniocervical complex, resulting in the instability of the neck and the head positions and possibly even the whole body posture. (2-5)

The anterior and posterior cervical muscles are concerned with the anteroposterior balance of the head position while the sternocleidomastoid muscles are concerned with the lateral balance of the head position. (31) The masticatory muscles especially contribute to the determination of the position and stability of the head. (32) If hypertonicity occurs in either of these muscles, a disharmony with other groups of muscles will result. These influences lead to instability of head posture, which affects the postural control system. As a result, the maintenance of natural standing posture is difficult. (6,15,33)

Based on these reports, harmony between bilateral masticatory muscles is an important factor in the stability of head posture. The present results found that body posture was less stable when subjects maintained their mandibles in the right eccentric mandibular position compared to when they bit down in centric occlusion (Figure 10). This result suggests the following possibility: The shifting of mandibular position from centric occlusion to right eccentric position caused a disharmony between bilateral masticatory muscles. This disharmony may have affected the bilateral activity of the sternocleidomastoid muscles as well. (11,16-18) The disharmony of the masticatory and sternocleidomastoid muscles may have caused changing of the proprioceptive inputs in these muscles. Furthermore, changing of the afferent information coming from the mechanoreceptors in the periodontal membrane may have occurred, because the tooth contact was only between upper and lower canines in the right eccentric mandibular position. Consequently, these bilateral disharmonies of the neuromuscular system may have led to the instability of the head position and possibly even the body posture.

Milani (5) reported that although wearing an occlusal splint resulted in changing postural attitude, the effect did not appear immediately but required a period of muscular adaptation. His splint was most effective alter two weeks of wear. The present results showed that there were no significant differences in the stability of body posture between centric occlusion and the corrected mandibular position (Figures 9 and 10). In agreement with Milani's report, the present results showed that when subjects maintained their mandibles in the corrected mandibular position, muscular adaptation in the whole body was not acquired immediately, and adaptation did not appear as a change of body posture in the corrected mandibular position for the time tested.

Body posture is maintained by the sense of equilibrium which consists of vestibular sensation, visual sensation, and somatic sensation. (1,11) When the center of gravity changes its position in space, the neuromuscular system must compensate so that the center of gravity remains in a balanced position. (3) The present results found that there were no significant differences in the distribution of loot pressure by changing mandibular positions compared to that in centric occlusion anteroposteriorly and laterally (Figures 11 and 12). These results suggest that changing mandibular positions did not affect the postural balance both anteroposteriorly and laterally.

To alter body posture in this study, a heel lift was inserted under the right toot. As a result, postural balance shifted significantly to the right side and backwards (Figures 11 and 12). These results indicated that altering body posture by changing leg length shifted the postural balance to that same side immediately. Nobili (6) reported the following: 1. There was a correlation between the Class III malocclusion and a posterior body posture, and on the other hand, between Class II malocclusion and an anterior body posture. 2. This could be explained by a forward and a more vertical head position which are linked respectively to Class II and Class lit malocclusion as demonstrated by other authors. (33-35) Furthermore, there is a report which statesy, (11) "the shifted side of the weight distribution corresponded with the changed side of the head position laterally." The present results suggest that altering body posture by changing leg length may have shifted both the postural balance and the head position to that same right side, indicating a compensatory mechanism of body posture.


When subjects bit down from the resting position to centric occlusion, there were no differences in the stability and shifting area of mandibular position between heel lift and no heel lift under the right foot (Figures 13 and 14). Occlusal force distribution shifted significantly to the right side with the heel lift compared to no heel lift (Figures 15 and 17). One can infer that when subjects bit down from the resting position to centric occlusion with a heel lift under the right foot, their head position may have shifted to the right side. (6,11) When the head position shifted to the right side, the mandibular resting position may have shifted to the same side in response to gravity forces. The distance between maxillary and mandibular dental arches on the right side is reduced compared to he neutral head position. This right sided mandibular posture and the right sided reduced interarch distance compared to the left side may have caused initial tooth contact to shift to the right side and the occlusal force distribution to be higher and more concentrated on that side.


Conclusion

1. Body posture was more stable when subjects bit down in centric occlusion than when they maintained their mandibles in the other mandibular positions (rest position, placebo position and right eccentric mandibular position).

2. Changes in body posture affected occlusal force distribution.

3. Altering body posture by changing leg length shifted the occlusal force distribution to the same side that had a heel lift.

Based on the present study, it was found that changing mandibular position affected body posture and conversely, that changing body posture affected mandibular position. In a clinical setting, when dental occlusion is developed and finished, body posture should be taken into account. This may prove to be important in patients undergoing full mouth reconstruction. Dental restorations and adjustments are completed with the patient sitting down. If a patient has a length discrepancy, hip rotation or any other problem altering body posture, occlusal contacts may differ as the patient stands up and starts walking. The patient will notice premature dental contacts and may voice his/her concern regarding an uncomfortable bite. At that point, attention to posture and examining the occlusion while the patient is sitting and again while standing would help resolve the problem.

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Address for correspondence:

Dr. Emad F. Abdallah

Tufts Craniofacial Pain Center

Tufts University, School of

Dental Medicine

One Kneeland Street

6th Floor

Boston, MA 02111

E-mail: emad.abdallah@tufts.edu

Dr. Kiwamu Sakaguchi is an assistant professor at the Department of Oral Functional Prosthodontics at Hokkaido University Graduate School of Dental Medicine, Japan. He received his D.D.S. degree at Hokkaido University in 1995 and his Ph.D. degree from the same university in 1999. He joined the Craniofacial Pain Center at Tufts University where he engaged in research from 2003-2004.

Dr. Noshir R. Mehta is a professor and chairman of general dentistry, director of the Craniofacial Pain Center and Assistant Dean of International Relations at Tufts University School of Dental Medicine. He is a diplomate of the American Board of Orofacial Pain and is a fellow of the International College of Dentists and of the American College of Dentists. Since receiving his D.M.D. degree and his M.S. in periodontics at Tufts University, he has been involved in occlusion research. Dr. Mehta has lectured internationally on TMD/MPD and has published numerous scientific papers.

Dr. Albert G. Forgione is Chief Clinical Consultant at the Craniofacial Pain Center at Tufts University School of Dental Medicine. He received a Ph.D. in psychology from Boston University and then joined Tufts University and lectured in behavioral medicine. Dr. Forgione established the first TMJ center at Tufts University School of Dental Medicine with Dr. Mehta in 1978.

Dr. Emad F. Abdallah is an Assistant Professor at the Craniofacial Pain Center, Tufts University School of Dental Medicine. He received his D.M.D. degree, certificate in Orthodontics, Masters of Science degree and certificate in temporomandibular disorders and orofacial pain from Tufts University. He is a diplomate of the American Board of Orofacial Pain. Dr. Abdallah has lectured internationally on orthodontics and orofacial pain.

Dr. Atsuro Yokoyama is a professor at the Department of Oral Functional Prosthodontics at Hokkaido University Graduate School of Dental Medicine, Japan.

Manuscript received October 17, 2006; revised manuscript received July 12, 2007; accepted July 19, 2007

Table 1
Testing Sequence and Randomization *

Group I Group II
(n=22) (n=23)
MatScan section MatScan Section

Centric occlusion RP
RP Centric occlusion
CMP (Box A **) HL-CO
PP (Box B **) REMP (Box A **)
REMP (Box C **) PP (Box B **)
HL-CO CMP (Box C **)

T-Scan section T-scan section

NS-CO HL-CO
HL-CO NS-CO

* Each subject was randomly assigned to one of two
groups, based on the table of random numbers. The only
difference between group I and group II was the sequence
of the testing.

** Three wax registrations were made and each was placed
in a box (A, B, and C).

Abbreviations: RP, resting position; CMP, corrected
mandibular position; HL-CO, heel lift--centric occlusion;
REMP: right eccentric mandibular position; PP: placebo
position; NS-CO: centric occlusion.

Source Citation
Sakaguchi, Kiwamu, et al. "Examination of the relationship between mandibular position and body posture." CRANIO: The Journal of Craniomandibular Practice 25.4 (2007): 237+. Gale Sciences Standard Package. Web. 17 May 2010.

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Disclaimer:This information is not a tool for self-diagnosis or a substitute for professional care.