Habitual Opening Research Articles

Condylar Movements of Temporomandibular Disorder Patients with Intermittent Lock: A Pilot Study

The purpose of this study was to clarify which direction of the condylar path is advantageous for releasing TMJ intermittent lock. The subjects were ten patients with temporomandibular disorders (TMD) and intermittent lock caused by anterior displacement of disks without obvious medial or lateral displacement. The patients could not open their mouths fully in habitual opening but could open fully in an intentional winding opening with reduction of the anteriorly displaced disks (winding opening). The two kinds of movement at the kinematic condylar point were measured in each subject and compared. The length of the condylar path in winding opening was significantly larger than that in habitual opening. The affected side condyle of winding opening traced medio-inferior paths in the early part of the condylar translation in comparison with habitual opening. From the viewpoint of the condylar path, the medio-inferior direction of condylar translation is thought to be advantageous for releasing intermittent lock.

The Advantageous Direction of Jaw Movement for Releasing TMJ Intermittent Lock

The purpose of this study was to clarify which direction of jaw movement is advantageous for releasing TMJ intermittent lock. The subjects included ten patients with TMJ intermittent lock who could not open their mouths fully in habitual opening paths (habitual opening), but could open fully in intentionally winding opening paths (winding opening). The following movements were analyzed: habitual opening, winding opening, lateral border opening to the contralateral side (contralateral opening), lateral border opening to the affected side and anterior border opening. The incisal points in winding opening tended to trace antero-lateral paths that were shifted toward the side opposite the affected joints in comparison with habitual opening. In addition to winding opening, the success rate in releasing locking of contralateral opening was significantly greater than that of habitual opening. The findings demonstrated that contralateral movements directed toward the nonaffected side are advantageous for releasing the intermittent lock. The patients will have a better chance of releasing the intermittent lock by themselves, when opening path shifted to the nonaffected side is recommended as the first choice.

Incisal Paths During Habitual Mouth Opening and Closing Movements of Children with Anterior Reverse Bite in the Early Mixed Dentition

The purpose of this study was to investigate whether the pathways of habitual mouth opening and closing in children with anterior reverse bite in the early mixed dentition differed from those of children with normal occlusion. The two subject groups for this study were composed of ten children with anterior reverse bite (reverse bite group) and twelve children with normal occlusion (normal occlusion group), respectively. These movements were measured by an optoelectronic analyzing system with six degrees of freedom. Movements of the incisal point were projected on the sagittal plane to characterize the paths, and sagittal angles between the incisal path and the horizontal plane were calculated and compared. Opening and closing sagittal angles in the reverse bite group were almost equal over the entire pathway, indicating that the pathways of habitual mouth opening and closing were similar. In contrast, all opening and closing sagittal angles in the normal occlusion group were different, especially close to maximum intercuspation, indicating that their pathway of habitual mouth opening differed from their mouth closing pathway. In conclusion, children with anterior reverse bite in the early mixed dentition have different patterns of habitual mouth opening and closing movements than children with normal occlusion.

Relationship between the Lower Incisal Point and Condylar Point during the Habitual Opening Movements of the Mandible in Children with Primary Dentition

Relationship between the Lower Incisal Point and Condylar Point during the Habitual Opening Movements of the Mandible in Children with Primary Dentition

Incisal and condylar paths during habitual mouth opening movement of children with anterior reverse bite in the primary dentition.

The purpose of this study was to evaluate whether the path of habitual mouth opening was influenced by anterior reverse bite malocclusion in children. Two groups of children with the primary dentition were chosen: (i) 10 children with anterior reverse bite (reverse bite group) and (ii) 10 with normal occlusion (normal occlusion group). Their habitual mouth opening movements were measured by an opto-electronic movement-analysing system with 6 d.f. at a sampling rate of 100 Hz. These movements were projected on the sagittal plane at the incisal and condylar points. To characterize the path, we used the angles between the path and the horizontal plane. In the initial stage of opening, the incisal path of the reverse bite group was displaced more posteriorly from the intercuspal position than that of the normal occlusion group. However, as opening continued, the direction of the path of the reverse bite group was more anterior than those of the normal occlusion group. During the entire opening movement, the condylar path of the reverse bite group was flatter than those of the normal occlusion group. In conclusion, it was demonstrated that anterior reverse bite in the primary dentition clearly affects the paths of habitual opening movements.

Influence of tooth contacts during mandibular retrusion on terminal jaw relations and EMG activity during habitual opening and closing movements

The purpose of this study was to clarify the influence of tooth contacts during mandibular retrusion on terminal jaw relations (TJR) and the surface EMG activity during habitual opening and closing movements. The age of five healthy subjects were 25 to 28 years. The maxillary stabilization splints with steep retrusive contacts (S-SP) and with flat retrusive contacts (F-SP) were prepared for each subject who was instructed to wear S-SP for one week and then to wear F-SP for one week after an interval of two weeks without S-SP. The EMG activity of the masseter and temporal muscles and the TJR during habitual opening and closing movements using a device for recording jaw movements in 6 degrees of freedom were simultaneously measured by an intraoral central bearing device. The results were as follows: 1. The TJR recorded after wearing F-SP shifted more posteriorly than that of wearing S-SP. 2. The posterior temporal muscle activity after wearing F-SP, compared with that of wearing S-SP, resulted in a significant increase. In conclusion, the elimination of the retrusive guidance caused the predominance of posterior temporal muscle activity, and posterior displacement of the mandible.

マンディブラーキネジオグラフによる口唇・口蓋裂患者の下顎運動の評価

We used a mandibular kinegiograph (MKG) to evaluate mandibular movement in cleft lip and/or palate patients, especially those who received orthodontic treatment. A total of 25 patients with complete unilateral cleft lip and palate (UCLP group) who had completed orthodontic treatment at the Clinics for Maxillo-oral Disorders, Tohoku University School of Dentistry, and 25 non-cleft volunteers (control group) of similar age were studied.Tracings of 10 variables of three major movements of the mandible (habitual opening and closing stroke, rapid opening and closing stroke, and rest position) were recorded and assessed by pattern analysis. Furthermore, the intensity of the mandibular movement disorder was classified and evaluated by scoring the 10 variables of mandibular movement on a scale of from 0 to 10 to derive the total mandibular kinetic score (TMK score). The results obtained were as follows:1. In the individual pattern analysis of habitual opening and closing stroke, rapid opening and closing stroke and rest position, more aberrant movement patterns were seen in the UCLP group than in the control group.2. In the TMK score evaluation, the mean TMK score in the UCLP group was 4.5 as compared with 1.8 in the control group, showing that the intensity of mandibular movement disorder was also higher in the UCLP group than in the control group.3. Maxillomandibular asymmetry seems to affect the mandibular movement disorders in UCLP patients who undergo orthodontic treatment.4. This study showed that the analysis of mandibular movement is important in the orthodontic care of cleft lip and/or palate patients. Further analyses of factors affecting mandibular movement are needed.

A study of the coincidence of the right and left condylar pathway in habitual opening movement

A study of the coincidence of the right and left condylar pathway in habitual opening movement

The effects of surgical-orthodontic correction of skeletal class III malocclusion on mandibular movement

The effects of surgical-orthodontic treatment on mandibular movement were studied using the mandibular kinesiograph in 30 patients with skeletal class III malocclusion that was corrected by the sagittal split osteotomy (27 patients), a combination of the sagittal split osteotomy and body ostectomy (2 patients), or the sagittal split osteotomy and a posterior alveolar osteotomy of the maxilla (1 patient). Postoperatively, the mean maximum anterior and posterior excursions of the mandible increased significantly from 4.1 to 6.7 mm and from 0.6 to 2.6 mm, respectively. The lateral excursion to the right and left sides also showed significant increases from 4.8 to 7 mm and from 5.5 to 7 mm, respectively, after surgery. In analysis of the habitual and rapid opening and closing movements of the mandible, marked impairment was not observed in most patients except for crossing and discrepancy in the tracings of the habitual opening and closing movements in the sagittal plane observed in 11 patients. These findings were observed in only one patient postoperatively. The results indicate that the surgical orthodontic correction of skeletal class III malocclusion has favorable effects on the function of the mandible.

Centers of rotation during jaw movements.

Anatomists consider the articulation of movable joints to be complex, involving movable instantaneous centers of rotation (ICR). However, prosthodontists often treat the temporomandibular joint (TMJ) as a model of a simple hinge. The aim of this study was to examine the case for a movable ICR during habitual opening and closing jaw movements. Young, dentate subjects were examined with a kinesiograph. Jaw movements were performed and recorded. The center of rotation of each movement pattern was identified, and its location related to the position of the TMJ. The results showed that opening and closing jaw movements were predominantly non-coincident, with a movable ICR located at a variable distance and direction from the TMJ. There was no evidence to suggest that the TMJ functioned as a simple hinge during jaw movements.

下顎枝矢状分割法を施行した骨格型下顎前突症の術前評価 顎運動の変化について

This study investigated the pre and post-operative changes of mandibular movement by means of mandibular kinesiograph for mandibular prognathism which indicated sagittal splitting ramus osteotomy. After surgery, the following was observed.1. On the frontal plane for habitual opening and closing movement, the condition of asymmetry or deviation decreased.2. The smoothness in the opening and closing movement speed increased.3. There was no notable change observed in the stability of rest position or the relation ship between the rest position and intercuspal position.4. On the frontal plane of the lateral gliding path, the angle of the path tended to resemble that of the normal group.

The effect of changing the maxillomandibular relationship by a bite plane on the habitual mandibular opening and closing movement.

The relationship between the change of afferent information from occlusal contacts and its influence on the jaw muscles was investigated. For this purpose, the following questions were posed and experimental studies designed. If the subject was given habitual occlusal contacts in centric relations with a bite plane, were the habitual mandibular closing and opening movements influenced? Second, was it easier for the subjects to accomplish regular habitual mandibular opening and closing movements, when the bite plane was inserted and removed? From the results it could be concluded that the centric occlusal contacts in centric relation were more physiological for the jaw muscles. In addition, when the new occlusal position was coincident or close to the centric relation, it was easier for the subject to study and acquire the new habitual mandibular opening and closing movement.

習慣的下がく開閉運動経路に関する実験的研究 バイトプレーンによる影響について

習慣的下がく開閉運動経路に関する実験的研究 バイトプレーンによる影響について

Study on the Axis of small Opening and Closing Movement of the Mandible in and around Intercuspal Position (2nd. Report)

To investigate the mounting method of the cast to the articulator using inter occlusal record with a certain thickness for the aim to realize the intercuspal position, we studied the axis of habitual small opening and closing motion of the mandible, using 5 dentulous subjects who are normal in stomatognathic system.We sought for position and displacement distance of “N” axis which is smallest moveing point when mandible takes habitual opening and closing motions, “H” axis which is the smallest moving point when mandible takes terminal hinge motion and “C” axis which is average condyle point.Further more we analyzed mathematically anteropostero gap in anterior region based on positional difference between the axis used mounting and “N” axis. The results were as follows:1.“N” axis existed 4.5 mm anterioly, 50.5 mm posterioly, 2.5 mm-5.2 mm inferioly from “C” axis. The position of “N” axis had a variety among subjects.2. Displacement area of “N” axis in habitual small opening and closing motion of the mandible is the smallest of the other and is 1/1.4-1/27.0 compared with “C” axis and 1/1.3-1/48.6 compared with “H” axis.3. Not exceeding 0.2mm displacement of “N” axis is so small that “N” axis is valuable as mounting axis of the cast to the articulator and also “N” axis is valuable compared with “H” axis.4. Antero-postero gap in anterior region based on positional difference between the axis used mounting and “N” axis tend to be greater when “N” axis appear postero-inferior position and supro-anterior position from the articulator axis by mathematical analysis.5. Mathematical analysis shows farly large error when mounting without true mandibular opening and closing axis, therefore using “N” axis lead desirable result.

The Aspects of Mandibular Movements in Swallowing

The aspects of swallowing movements, habitual: opening and closing movements and rest position were investigated from functional points of view.Three dimentional measuring apparatus of the mandibular movements at the incisiorinferius combined with optical-fiber, motion-analyzer and electric-computer was used in coordination with teeth contacts apparatus with accelerometer and swallowing meter.The following conclusion is obtained based on the experimental result.1) The clinical mandibular rest position moves within about 1.5mm to anterior and posterior direction, about 1.4 mm to upper and lower direction, and about 1.0mm to right and left direction.2) In habitual opening and closing movements, the opening path is positioned in front of the closing path. Habitual opening and closing movements tend to be in a left and anterior position from the rest position.3) Intercuspal position has a narrow range within about 0.4 mm to anterior and posterior direction and to upper and lower direction and within about 0.3 mm to right and left direction.4) Tooth contact is recognized in empty swallowing with sitting and lying postures and in swallowing after mastication.5) Mandibular movement in swallowing is complicated. Ingeneral, it moves from posterior to anterior in empty swallowing. But it does not indicate a definite direction in swallowing after mastication in comparison with empty swallowing.6) Mandibular in swallowing is held in a range of 0.9mm and the range of slidingis within 0.5mm before and after the fixation.7) Swallowing movement in lying posture is slow and powerful, and in swallowing after mastication, tooth contact is strong than in sitting posture.

Function of Temporomandibular Joint during Habitual Opening and Closing Movements

Function of Temporomandibular Joint during Habitual Opening and Closing Movements

The human temporomandibular joint: Kinematics and actions of the masticatory muscles

The shape of the joint surfaces do not govern movements, but these are determined rather by the synergistic action of muscles. The results can be summarized in the following points *: 1. Large variations were found in the patterns of opening and closing, as well as forward and lateral movements because of the laxity of the joint tissues. 2. The instantaneous axis shifted very much during the whole of the opening movement. No single axis could be shown. 3. The angle of opening and the amount of translation of the condyles were calculated. In maximum opening the condyles, as a rule, glided forward some-what further than to the top of the eminentiae. The condyles could be held back actively so that no or only a small amount of translation was effected during the first part of the habitual (natural) opening. 4. The total range of movement of the jaw was seldom utilized during such functions as speech and singing. The opening angles used during speech were generally only from 1.5 to 4.5 degrees. While singing, opening degrees of 4.3 to 8.6 were used as compared to 20 to 30 degrees of total opening. Ten degrees corresponds to 7 to 8 mm. of total condyle translation. Usually, during function, only 2 to 3 mm. of horizontal translation was used. 5. The movement area in the median plane for an anterior point of the mandible did not correspond fully with those described by Henke 4 and others. 6. Sagittal translations of the condyles were the largest during lateral movements. 7. The axes for lateral movements were posterior to the condyles. 8. A bodily side shift of the mandible of 2 to 3 mm. was possible. 9. The total angle of rotation (from one extreme lateral position to the other) was calculated to be 30 degrees on the average. 10. Freer lateral movements of the mandible could be performed when it was protruded than could be from its posterior position. 11. Masticatory movements were combinations of opening, forward, and lateral movements. 12. The digastric, geniohyoid, genioglossus, and mylohyoid muscles could cause a lowering of the mandible (opening movement), but not a movement of natural character. 13. The combined effect of the external pterygoid muscles and the afore-mentioned other muscles resulted in an opening movement pattern resembling that obtained in living individuals. The same was true for lateral movements. Many muscles must work together to produce a natural movement. 14. Contraction of the external pterygoid muscles precludes the necessity for extreme shortening of the digastric muscles.