Maximum Interincisal Distance Research Articles

若年者に認められた両側性筋突起過形成症の１例 術前後の筋突起の形態的変化

Bilateral enlargement of the coronoid process of the mandible, associated with limited mouth opening, is rare.This report describes a case of bilateral hyperplasia of the mandibular coronoid process in a 13-year-old boy. Trismus was diagnosed on a dental examination at school.Panoramic radiography showed that both coronoid processes extended above the zygomatic arch. His maximum mouth opening was 27mm (interincisal distance).Coronoidotomy was performed via an intraoral approach under general anesthesia, and continuous mouth-opening training was done after surgery. Thirty-four months after the operation, the maximum interincisal distance was maintained at 44mm. The mandibular coronoid process was remodeled posteriorly to prevent interference with mouth opening.

The influence of the spring activator on the mobility of the lower jaw in traumatically injured patients.

For functional rehabilitation and improvement of mandibular mobility, 14 patients with dislocated collum or collum fracture dislocations were treated with a spring activator after surgical-conservative treatment. With an interincisal distance of < 12 mm, therapy was started with a loop spring. The average age of the patients was 26.6 years. Eight patients showed additional traumatic injuries, 2 patients were seriously polytraumatically injured. The clinical investigations referring to the maximum mouth opening and maximal interincisal distance resulted in a good to very good functional rehabilitation in all cases. The average maximal interincisal distance of 31.7 mm at the beginning of the spring activator therapy could be increased to 47.3 mm. The largest increase of the maximal interincisal distance was observed after 4 weeks of therapy. The type of reaction, however, differed interindividually. Three patients showed a spontaneous improvement of the interincisal distance within the first 2 to 3 weeks of removal of intermaxillary fixation, whereas 7 patients showed no improvement or only slightly improved values until insertion of the spring activator. An enlargement of the interincisal distance could be achieved in almost every patient within a relatively short period of time despite a drastically reduced mouth opening. Consequently, because of its mode of action in the form of a neuromuscular influence, the spring activator is especially suitable for the functional rehabilitation of patients with fractures of the condylar process.

Long-term outcomes of nonsurgical treatment in nonreducing anteriorly displaced disk of the temporomandibular joint

Objectives. The aim of this study was to evaluate long-term outcomes of nonsurgical treatment in patients with persistent anterior disk displacement without reduction of the temporomandibular joint. Study Design. Thirty-five patients were treated with occlusal splints, and 12 patients underwent additional occlusal treatments after splint treatment. These patients were evaluated clinically and radiographically. At least 2 years after the treatment, the 34 patients' symptoms were assessed with the use of a questionnaire. Results. The mean maximal interincisal distance (MID) was 27.6 mm before treatment and 44.4 mm at the end of treatment ( p < 0.001). Before the treatment, all 35 patients had complained of pain, and mild pain persisted in 9 patients at the end of treatment. Flattening of the condylar head and of the articular eminence increased in prevalence from 12.1% and 9.1%, respectively, before treatment to 54.5% and 51.5%, respectively, at the time of follow-up observation. At the time of the survey, the mean self-reported MID was 46.8 mm ( p < 0.01). Conclusions. After the nonsurgical treatment, the clinical signs and symptoms improved significantly, although the prevalence of osteoarthrotic findings increased.

慢性関節リウマチ患者の顎関節症状に対する顎運動療法の効果

Rheumatoid arthritis (RA) is a chronic inflammatory disease with immunologic abnormalities. Although the temporomandibular joint (TMJ) can be involved, early changes of the TMJ affected by RA are unclear, and the treatment for temporomandibular disorders (TMD) in patients with RA is not established yet. Physiotherapy is effective for general joints with RA but its effect for RA of the TMJ is unknown. The clinical effects of physiotherapy for TMD in RA patients was investigated. Five patients with RA visited our department with complaints of the TMD. Physiotherapy, including exercises of TMJ movement and mastication training were stasted, bilaterally and simultaneously. Clinical findings showed an increase in maximal interincisal distance with no pain after therapy in 4 patients. No patient had anterior open bite or TMJ ankylosis in the follow-up period (2.5 to 5.3 years). These results suggest that physiotherapy is also effective for the TMD in RA patients.

Trismus and pain after removal of impacted lower third molars

Purpose: This study evaluated trismus and pain after removal of impacted lower third molars and investigated whether these responses were related to difficulty of surgery. Patients and Methods: A consecutive series of 104 patients, all of whom underwent removal of an impacted lower third molar under local surgery, was studied. Difficulty of surgery was evaluated on a modified version of the Parant scale: I, extraction with forceps only; II, extraction by ostectomy; III, extraction by ostectomy and coronal section; IV, complex procedures. Trismus was evaluated in terms of maximum interincisal distance (MID) 1 and 5 days after surgery. Pain was evaluated on the basis of reported analgesic use 1 and 5 days after surgery. Results: Among group I subjects, mean day 1 MID did not differ significantly ( P > .05) from mean presurgery MID, whereas mean day 1 MID in groups II, III, and IV was significantly lower than before surgery. In groups II, III, and IV, mean day 5 MID remained lower than before surgery. The proportion of group I patients using analgesics was significantly lower on both days 1 and 5 than the proportion of patients using analgesics in groups II, III, and IV. In all groups, the proportion of patients using analgesics dropped significantly between days 1 and 5. Conclusion: Trismus is less severe after simple (forceps-only, grade I) extractions than after surgical extractions (grades II to IV). However, trismus severity after surgical extraction does not depend on difficulty of surgery. Pain, as revealed by reported analgesic use, is likewise less severe after simple extractions. Regardless of extraction type, pain declines between days 1 and 5 postsurgery.

Fractures of the condyle and the condylar neck: Conservative versus operative treatment

Purpose: The aim of the study was to investigate the results of non-surgical treatment of condylar fractures in a group of 60 patients with 71 condylar fractures, in order to establish a protocol to select patients for surgical treatment of condylar fractures.Material: Out of a group of 91 patients treated in a non-surgical fashion, 60 patients with a total of 71 condylar fractures responded to the request for follow-up.Methods: Retrospective study, including clinical analysis of occlusion, asymmetry at rest and during mouth opening, maximum interincisal distance, signs of TMJ-dysfunction and analysis of radiographic data, i.e. shortening of the ascending ramus as measured on sequential orthopantomograms.Results: There were five patients (8%) with an unacceptable malocclusion of which one also had considerably limited mouth opening. Fifty-five patients (92%) had none or only minor signs of TMJ-dysfunction not requiring further treatment.Conclusion: Only in selected patients with shortening of the ascending ramus of 8 mm or more and/or considerable displacement of the condylar fragment, surgical repositioning and rigid internal fixation should be considered.

Relation between Maximal Interincisal Distance and Age in Children and Adolescents

Relation between Maximal Interincisal Distance and Age in Children and Adolescents

Angle of mouth opening measurement: reliability of a technique for temporomandibular joint mobility assessment.

The maximal interincisal distance added to the vertical overlap is generally used as a measure for temporomandibular joint mobility. However, the length of the mandible also has an influence on this measure. The angle of mouth opening as a measure of temporomandibular joint mobility is independent of the length of the mandible. The aim of the study was to develop a mandibular goniometer to measure the angle of mouth opening and to test its reliability. Ten subjects, two males and eight females (mean age 28.1 years) participated in the study. The measurements were performed during four independent sessions of three measurements each. The results were analysed with ANOVA. Intra-observer variability was found to be 2.0 degrees when the result of all the measurements were analysed, and were found to be 1.2 degrees when the mean value of the sessions were used for analysis. Based on the results of this study it can be concluded that the angle of mouth opening can be measured reliably.

顎関節症患者の病型分類による臨床統計的観察

Four hundred and eight patients with arthrosis of the TM J, who visited our clinic from January, 1987 to December, 1989 were classified into 5 types based on a newclassification proposal advocated by the Japanese Society of Temporomandibular Joint in 1986.The patients consisted of 93 males and 315 females in the ratio of 1: 3. 4. Fifty-eight cases (14.2%) were classified into type I, 21 (5.1%) in type II, 263 (64.5%) in type III. 53 (13.0%) in type IV, 5 (1.2%) in others type and 8 (2.0%) were unclassified. In type III, 136 (33.4%) cases had an anterior disc displacement with reduction 103 (25.2%) had an anterior disc displacement without reduction, and 24 (5.9%) had an intermittent closed lock.The sex ratio by type was 1: 3.5 in type I, 4.3: 1 in type II, 1: 4.0 in type III, and 1: 6.6 in type IVThe average age was 38.1 years old in type I, 41.7 in type II, 32.0 in type 11, and 54.6 in type IV. The average age was the lowest in patients with intermittent closed lock and the highest in type IV.Even the cases of types II, III, IV frequently accompanied a pain at the masticatory muscies. The patients diagnosed as type II showed male predominance and a relatively acute course in their histories. According to arthrographic examinations performed on patients who complained of painful masticatory muscles alone and whose maximal interincisal distance was more than 40mm, it was revealed that these patients belonged to anterior disc displacement without reduction. The differentiation from type I was sometimes difficult only by clinical findings in such cases. The cases of which bone changes of the TMJ are not so rcmarkable and the discs are displaced, could not be clearly determined as either type III or type IV. The judgment of type II was most difficult because of its pain characters being the sole determinant.The 4 cases classified into others type showed morphologic changes in the disc, such as perforation or adhesion, although disc displacement was not identified.Although it is not easy to classify all of the cases only by their clinical symptoms, it is thought that the new classification proposal fundamentally has an advantage of simplifying the complicated etiology of arthrosis of the TMJ.

Longitudinal study of functional conditions in the masticatory system in Flemish children.

A 5-yr longitudinal study on occlusal and functional parameters has been made in 75 children aged 8-11. They were selected at random from an original group of 510 studied 5 yr earlier. The following parameters were measured: frequency of frontal open bite lateral and frontal crossbite, the attrition on molars and on front teeth, the contacts on lateral excursion, pain on condyle palpation, TMJ clicking, deviations in the opening and lateral movement, and the maximal interincisal distance. There was an increase in the percentage of deep bite and crossbite. Attrition on molars was seen in 41% and on front teeth in 13% of the children. No real pattern could be observed as a function of age. The mean maximal opening range was 43.7 mm, varying between 23 and 52 mm. Restricted opening was found in one girl. In 60% a deviation in the opening has been found. In 26% TMJ sounds were observed and 28% had pain on condyle palpation. In most of the children the symptoms were very mild to moderate. No significant correlation could be found between dysfunctional signs and occlusal parameters. The present results did not provide any conclusive answer to the tremendous increase in dysfunctional signs over this 5-yr period. The treatment need is, however, low and should not be overestimated.

顎関節症のとう痛に対する局麻剤の関節腔内パンピングによる鑑別法

In the outpatient clinic, we have many patients who suffer from temporomandibular joint disorders. These vary from MPD syndrome to osteoarthrosis, and many cases have tender spots or areas on the temporomandibular joint region and/or masticatory muscles. Further, they frequently have masticatory muscle pain when opening the jaw.This paper presents the results of our research on the differential diagnosis for tendernesses and pain on opening the jaw in the temporomandibular joint region and the masticatory muscles by joint cavity pumping with local anesthestic.The areas of tenderness and jaw-opening pain in 65 patient suffering from temporomandibular joint disorder were examined and recorded before and after anesthetizing the upper joint cavity with 1% Xylocaine. Maximum interincisal distance was similarly recorded.The results were as follows:In the area surrounding the upper joint cavity including the lateral pterygoid muscle, the tenderness and jaw-opening pain vanished almost entirely after anesthesia. This was considered a direct infiltrative effect of the local anesthesia.After the anesthesia, 86% of the tendernesses on the sternocleidomastoid muscles, and 66% of those on the posterior belly of the digastric muscles vanished, while the disappearance rates on the masseter, temporal, and medial pterygoid muscles were 50-60%.Apart from the temporomandibular region, pain on opening the jaw was found on the masseter, temporal, posterior belly of the digastric muscles, and medial pterygoid muscles before anesthesia. The disappearance rates after anesthesia were 90-100% except for the pain of the posterior belly of the digastric muscles, for which the rate was 66%.These results suggest that more than 88% of the tendernesses on the sternocleidomastoid muscle, more than 60% of the tendernesses and jaw-opening pains on the digastric muscle, and more than half of the tendernesses and almost all of the jaw-opening pains in the jawclosing muscles are referred pains from the temporomandibular joint.The tendernesses that had no change after anesthesia were considered to be derived from spasms of the muscles proper.Generally, maximum interincisal distance increased after anesthesia. The average distance was 34mm before anesthesia, but increased to 41mm after anesthesia. In a few cases, however little or no change was found in those distances. In these cases, pathological changes were found in the joint cavities arthrographically or arthroscopically.

Morbidity associated with temporomandibular joint arthrography in clinically normal joints

To document the short- and long-term morbidity of arthrograms done on clinically normal temporomandibular joints, 62 arthrograms were performed on 31 asymptomatic volunteers. All subjects kept a record of any joint pain they experienced during the next five days and were examined by one of the authors at five days and again at two months. Maximum interincisal opening distance was recorded before the arthrogram and at both postarthrographic evaluations. No subjects complained of severe (grade 3) joint pain. Sixteen joints were recorded as moderately painful (grade 2), 32 as mildly painful (grade 1), and 14 as not painful (grade 0). Ten of 31 subjects described transient changes in occlusion one week after arthrography but none of the changes persisted until the two-month examination. Maximum interincisal distance was significantly decreased at one week but not at two months. These findings, although gained from asymptomatic subjects, suggest that complications of arthrography are probably minor and transient when performed by an experienced arthrographer.

Treatment of anterior displaced meniscus with a flat occlusal splint: From J. Dent. Res. 63: 172, 1984

The aim of this study was to evaluate the long-term clinical and radiologic results of the retromandibular transparotid approach to displaced extracapsular subcondylar mandibular fractures.A prospective cohort study was conducted over a period of 5 years on patients surgically treated for displaced extracapsular subcondylar mandibular fractures by the retromandibular transparotid approach. Variables including the type of fracture, degree of mouth opening, fracture displacement, deviation, excursive movements of the mandible, and facial nerve function were monitored before and after treatment. Appropriate statistics were computed.Thirty-nine patients with 47 fractures were evaluated. There were 34 subcondylar fractures (located below the sigmoid notch) (87%), and 5 fractures were located in the head region in bilateral cases. Of the fractures, 31 (79%) were unilateral and 8 (21%) were bilateral. In a multivariate study, condylar coronal displacement, coronal sagittal displacement, difference in the ramal height, maximal interincisal distance, protrusive movements, and deviation of the mandible on opening showed statistically significant differences in pretreatment and post-treatment patients (P = .001). The interincisal distance was 46.8 mm (SD, 5.2 mm) postoperatively versus 24.1 mm (SD, 6.7 mm) before treatment. The average range of protrusion was significantly lower (P = .001) in patients before treatment, at 1.9 mm (SD, 1.2 mm), when compared with 6.1 mm (SD, 2.0 mm) postoperatively. During mouth opening, deviation of the mandible is often a sign of compensatory movement of the contralateral joint due to shortening of the ascending ramal height on the affected joint. The mean deviation of the mandible from the midline was 4.2 mm (SD, 1.0 mm) in patients before treatment, with a significant difference (P = .001) in patients after treatment, with a mean of 1.9 mm (SD, 0.995 mm). Temporary injuries to the facial nerve branches were observed in 3 cases (8%) 1 week after treatment, which later resolved within 3 weeks to 3 months.The retromandibular transparotid approach provides good exposure and facilitates accurate reduction and fixation of the subcondylar fragment with positive outcomes, good cosmetic results, and rare major complications. Most facial nerve injuries are transient in nature after this approach. A Synthes 2-mm titanium single mini-plate (West Chester, PA) provides stable results after fixation.

Epidemiologic survey of functional conditions of the masticatory system in Belgian children aged 3-6 years.

In this epidemiologic survey 510 children aged 3-6 yr were investigated. Several occlusal and functional parameters were measured: the maximal interincisal distance, the frequency of lateral and frontal crossbite, open bite, the number of tooth contacts on lateral excursions of 3 mm, the wear facets, deviations in opening, pain in muscles and in the TM-joints, TMJ sounds, parafunctional habits. The interincisal distance varied between 25 and 55 mm. This distance increased with age. Only five children had a hypermobility of the mandible (opening more than 55 mm) and 11 a restricted opening movement (less than 30 mm). 7.2% showed a lateral crossbite on the right, and 8.9% on the left, side. The percentage of an open bite decreased with age from 66.7% in the 3-yr-olds to 20.0% in the 6-yr-olds. 33% of the children had only one contact on the working side. As reported by the parents 7.7% had regularly bruxism but 21.8% showed wear facets on the molars and 40.7% on the front teeth. Only in three girls were the TMJ painful to palpation. Dysfunction only occurred in 3.5% of the sample.

A study of the use of occlusion splints in the treatment of acute and chronic patients with craniomandibular disorders

Thirty-three patients were treated for a 4-week period with splint therapy. Fourteen muscle and joint regions were palpated before and after treatment, and observable pain scores were recorded. Maximal comfortable interincisal distance and maximal interincisal distance were recorded before and after treatment. The following results were observed. 1. Of the 33 patients, 28 showed improvement in observable pain scores. The mean decrease was 4.4 ( p < .01). 2. Of the 33 patients, 27 showed increase in maximal comfortable interincisal distance. The mean increase in interincisal distance was 5.3 mm ( p < .01). 3. Of the 33 patients, 21 showed an increase in maximal mandibular opening; however, the increase of 1.7 mm was not statistically significant. 4. When the patients were divided into two groups according to the duration of symptoms, there was no significant difference between the groups' symptoms or their responses to treatment.