Comparison of maximum mouth-opening capacity and condylar path length in adults and children during the growth period

Evaluation of mandibular motion in adolescents with skeletal class II division 1 malocclusion during mandibular advancement using clear functional aligners: a prospective study

BACKGROUND

This study aimed to evaluate the characteristics of mandibular protrusive condylar trajectory in adolescents with skeletal Class II Division 1 malocclusion and the changes of condylar trajectory during mandibular advancement (MA) treatment using clear functional aligners.

METHODS

This prospective study consisted of a cross-sectional study and a longitudinal study. In cross-sectional study, sixty-one adolescents were divided into two groups: Class I (n = 30) and Class II Division 1 (n = 31). The condylar trajectory was measured and compared using the Mann-Whitney U test. The longitudinal study was the MA treatment group using clear functional aligner and consisted of 16 participants from Class II Division 1group. The condylar trajectory was collected at three-time points: pre-treatment (T1), during MA treatment at approximately 3 months (T2, 105.6 days average), and at the end of MA treatment (T3, 237.6 days average). The changes at T1, T2, and T3, as well as the symmetry between the left and right condyles across all groups, were examined using the Wilcoxon paired test.

RESULTS

A greater increase in the anteroposterior displacement and space displacement during protrusive movements was observed in the Class II Division 1 group compared with that in the Class I group, with a large difference being observed in the left and right condylar movements. The condylar anteroposterior displacement and space displacement decreased significantly at T2 and increased significantly at T3; however, no significant difference was observed between T1 and T3. A significant difference was observed between the condylar movement on the left and right sides at T1; however, no significant difference was observed at T2 and T3.

CONCLUSIONS

Adolescents with Class II Division 1 malocclusion had higher protrusive capacity than those with Class I. Moreover, their left and right condylar motion was more asymmetric. The range of condyle motion decreased first and then increased during MA therapy, and the left and right condyle movement became more symmetrical, which may be the adaptive response of neuromuscular function to the changes in jaw position.

Temporomandibular involvement in children and adolescents with juvenile idiopathic arthritis: a 2-year prospective cohort study

This study aimed to clinically evaluate temporomandibular joint (TMJ) involvement in juvenile idiopathic arthritis (JIA) and the ability to identify and/or predict development of TMJ-deformities over time using cone beam computed tomography (CBCT). The predictive value of self-reported TMJ pain was also assessed. A prospective longitudinal cohort study comprising 54 children with JIA, 39 girls and 15 boys, was performed. All children had active disease at baseline, 50% with the subtype oligoarthritis. Repeated clinical orofacial and CBCT examinations were performed over a two-year period. At baseline, 39% had radiographic TMJ deformities (24% unilateral, 15% bilateral), at 2-year follow-up, 42% (p > 0.05). Both progressing and improving TMJ deformities were observed. An association was found between TMJ-deformities and self-reported TMJ pain at baseline (p = 0.01). Maximum unassisted mouth opening (MUO) was smaller for children with TMJ-deformities (p < 0.05). The prevalence of palpatory muscle pain was high (48-59%) but not predictive of development of TMJ-deformities. TMJ noises increased over time and crepitations were associated with TMJ-deformities (p < 0.05). In conclusion, in children with JIA, self-reported TMJ pain and dysfunction were common and predictive of TMJ deformities. TMJ deformities were associated with smaller MUO and palpatory TMJ pain as well as crepitations. Trial registration. ClinicalTrials.gov Protocol id: 2010/2089-31/2.

Relationship Between Temporomandibular Ankylosis And Maximum Mouth Opening In Children

BACKGROUND

Pediatric dentists should have information regarding whether mouth opening is limited. In clinical practice, these professionals should collect and record oral area measurements at the pediatric patient's first medical examination.

OBJECTIVES

The study's aim developed the standard mouth opening measurement in children by using ordinary least squares regression to develop a clinical prediction model in children with Temporomandibular Joint Ankylosis before preoperative surgery.

METHODS

All participants completed their age, gender, and calculated height, weight, body mass index, and birth weight. Pediatric dentist performed all mouth-opening measurements. The oral-maxillofacial surgeon marked subnasal and pogonion points for the lower facial length of soft tissue. It was measured using the distance between the subnasal and pogonion with a digital vernier caliper. The widths of the three fingers (index, middle, and ring fingers) and four fingers (index, middle, ring, and little fingers) were also measured using a digital vernier caliper.

RESULTS

Maximum mouth opening showed that three-finger width (R2 = 0.566, F = 185.479) and four-finger width (R2 = 0.462, F = 122.209) had a significant influence on the Maximum mouth opening (MMO) (p < 0.001).

CONCLUSION

Pediatric dentists should collaborate with the treating maxillofacial surgeon to manage long-term treatment needs for individuals with Temporomandibular Joint Ankylosis.

A New Intraoral Six-Degrees-of-Freedom Jaw Movement Tracking Method Using Magnetic Fingerprints

We proposed a novel jaw movement tracking method that can measure in six degrees of freedom. The magnetic field generated by a permanent magnet paired with a small, low-power-consumption Hall effect magnetic sensor is used to estimate the relative distance between two objects-in this instance, the lower and upper jaws. By installing a microelectromechanical system (MEMS) orientation sensor in the device, we developed a mouthpiece-type sensing device that can measure voluntary mandibular movements in three-dimensional orientation and position. An evaluation of individuals wearing this device demonstrated its ability to measure mandibular movement with an accuracy of approximately 3 mm. Using the movement recording feature with six degrees of freedom also enabled the evaluation of an individual's jaw movements over time in three dimensions. In this method, all sensors are built onto the mouthpiece and the sensing is completed in the oral cavity. It does not require the fixation of a large-scale device to the head or of a jig to the teeth, unlike existing mandibular movement tracking devices. These novel features are expected to increase the accessibility of routine measurements of natural jaw movement, unrestricted by an individual's physiological movement and posture.

Temporomandibular joint involvement in children with juvenile idiopathic arthritis-Symptoms, clinical signs and radiographic findings

BACKGROUND

Although many children with juvenile idiopathic arthritis (JIA) develop arthritis and deformity of the temporomandibular joint (TMJ), many go undetected.

OBJECTIVE

This study investigates whether findings from patient history and clinical examination using the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) can be used to diagnose TMJ involvement.

METHODS

As a part of the screening program, 59 consecutive JIA patients age 7-14 years underwent a clinical examination according to RDC/TMD including self-reported orofacial pain and pain related to jaw function, and cone beam computer tomography (CBCT). Data were obtained from the patient's medical charts. Patients were divided into two groups based on the presence or absence of TMJ deformities on CBCT.

RESULTS

Self-reported TMJ symptoms before inclusion were reported by 52% of children with and 18% of children without TMJ deformities on CBCT (p = .020). On a group level, the maximum unassisted (mouth) opening (MUO) with and without pain was within the normal range, but children with TMJ deformities showed a significantly smaller MUO with pain (p = .035). A diagnosis of osteoarthritis and osteoarthrosis was more prevalent in children with TMJ deformities.

CONCLUSION

Although there were few differences between children with and without radiographic TMJ deformities, self-reported previous TMJ symptoms and reduced MUO with pain could indicate the presence of TMJ involvement. However, radiographic examinations are needed to confirm TMJ involvement. Thus, this study indicates that the RDC/TMD protocol is a blunt tool when targeting TMJ involvement in JIA.

Mandibular border movements: The two envelopes of motion

BACKGROUND

The envelope of motion is a diagrammatic representation of the mandibular border movements. Classically, those movements are carried out eccentrically; starting from the position of maximal intercuspation, the mandible describes an excursion movement until reaching maximal mouth opening. Reverse movements would describe a different path, but up to now concentric development of mandibular border movements has not been considered. Literature states that beyond mandibular border movements limits, no movement is possible. Therefore, it is of great interest to compare both paths-both envelopes of motion-and define the actual limits of mandibular movement.

OBJECTIVE

The aim of this study was to compare the geometric characteristics of mandibular border movements carried out eccentrically and concentrically by healthy subjects.

METHODS

Sixteen individuals aged between 18 and 27 years, molar class I and with no temporomandibular disorders, participated in the study. Eccentric and concentric mandibular movements were recorded using a 3D electromagnetic articulograph. Data were processed with computational scripts developed in MATLAB. Maximum mouth opening, trajectories, displacement ranges, polygon areas and chewing cycle area/ mandibular border movements area ratio were analysed.

RESULTS

The frontal plane showed significant differences in all the parameters evaluated. Higher values were registered in the concentric area of the border movement envelope (P = .008) and in the trajectories on both sides. Statistical differences were observed in polygon areas (P = .006) in the sagittal plane and right ranges (P = .046) in the horizontal plane.

CONCLUSION

Concentric mandibular movements revealed significant differences in three-dimensional trajectories in the frontal plane.

Correlation of Condylar Translation During Maximal Mouth Opening with Presence of Signs of Temporomandibular Joint Disorders in an Asymptomatic Population of 18-25 Years Age Group of Northern India

Objective(s):

The objective of this study was to determine the frequency of “subluxation” and presence of clinical signs of Temporomandibular Joint Disorder (TMD) in asymptomatic individuals and its distribution according to age and sex.

Materials and Methods:

The material investigated comprised of 200 asymptomatic subjects with 400 joints. The subjects were divided into two groups of 18-25 years and 50-60 years of age consisting of equal number of males and females. Clinical examination involved measurement of maximal inter-incisal distance, joint sounds and deviation. For radiological examination, Temporomandibular Joint (TMJ) open mouth close mouth view option (TMJ1/2) was used on a Digital Panoramic Machine. All the radiographs were traced to assess subluxation and anterior translation of the condyle. The statistical analysis was carried out using Statistical Package for Social Sciences (SPSS Inc., Chicago, IL, version 15.0 for Windows).

Results:

The prevalence of the signs of TMDs in the asymptomatic population was found to be very high and more predominant in females as compared to males. Furthermore, the older age group had comparatively less signs of TMDs. It was of interest that the subjects presenting with clinical signs of TMD were significantly less as compared to the subjects presenting with subluxation. The value of anterior translation was found to be more in females in the younger age group as compared to the males. Similarly, it was more in males as compared to females in older age group. But the mean anterior translation difference in females in 18-25 years and 50-60 years showed a statistically significant difference with P-value 0.017.

Conclusion:

Subluxation is a very common feature found in almost all the subjects in this study with a high prevalence. Hence, we may assume that the increased incidence of TMDs could be a direct result of the phenomena of subluxation. The decrease in mandibular length could be the cause of decreased mouth opening and increased subluxation.

Centric slide in different Angle's classes of occlusion

The purpose of this study was to test the possible differences in centric slide values between different Angle's classes of occlusion. The study included 98 participants divided into four groups: Angle's class I, Angle's class II, subdivision 1, Angle's class II, subdivision 2 and Angle's class III. All recordings were obtained using an ultrasound jaw tracking device with six degrees of freedom. The distance between the maximum intercuspation (reference position) and the centric occlusion was recorded at the condylar level. Anteroposterior, superoinferior and transversal distance of the centric slide were calculated for each participant, and the data were statistically analyzed (analysis of variance and Newman-Keuls post hoc test). No statistically significant difference was found in the anteroposterior and transversal distance of the centric slide between tested groups, while Angle's class II, subdivision 2 showed smaller vertical amount of the centric slide compared to Angle's class I and class II, subdivision 1. None of the 98 participants showed coincidence of centric occlusion and maximum intercuspation. Our results suggest that coincidence of the maximum intercuspation with the centric occlusion should not be expected. Smaller extent of the vertical distance of the centric slide could be morphological and a functional expression characteristic of the Angle's class II, subdivision 2.

Faculty-supervised measurements of the face and of mandibular movements on young adults

PURPOSE

The purpose of this study was to determine the average facial proportions and mandibular movement capacity of 316 first-year dental students who carefully recorded them on each other.

MATERIALS AND METHODS

This early exacting clinical experience was closely supervised by the authors in Columbus, Ohio during 1969-70. Five vertical and six horizontal distances were measured on each subject's face. An ala-tragus line and an occlusal line were drawn on the left side of the face to determine if these two lines were parallel. Measurements of mandibular movements involved maximum normal and hinge opening at the incisors and maximum amounts of right, left lateral and protrusive excursions of the mandible.

RESULTS

The ala width and distance between the tips of upper right and left canine cusps averaged (35.2 mm and 34.8 mm) but with very large individual variations. The distance between ala to occlusal plane lines was 29.9 mm at the tragus and 31.3 mm near the ala. The angle between orbitale and ala-tragus averaged 13.6 degrees.

CONCLUSION

The upper lip length was the most variable and the distance between the pupils was the most stable of the eleven facial measurements. The ala-tragus line and the occlusal plane lines were for all practical purposes parallel. Maximum jaw opening averaged 51.2 mm which was 3.0 times larger than maximal hinge opening of 17.2 mm. The maximum right plus left side jaw excursions (9.2 and 9.4 mm) totaled 18.6 mm, 2.3 times more than the 8.0 mm mean maximum forward protrusion.

Measurements of the sagittal condylar inclination: intraindividual variations

AIMS

Sagittal condylar inclination is an important parameter during fabrication of prosthetic restorations. Existing data about intraindividual variations of sagittal condylar inclination are scarce. The purpose of this study was to investigate intra- and interindividual variations of the sagittal condylar inclination, depending on the position of the condyle in the temporomandibular joint.

METHODOLOGY

The study included 51 subjects with Angle's Class I occlusion (21-32 years of age, mean 25.1). Measurements were done using an electronic axiograph. After a paraocclusal tray was fixed in the mouth, every subject had to make three protrusive movements, from which the device's software calculated the mean left and mean right sagittal condylar path. The mean left and right condylar path of each subject was divided into three equal sequences, based on whole condylar path length. Condylar inclination values for the first, second and third movement sequences were calculated.

RESULTS

Results showed significant differences between movement sequences (P < 0.05). For the left joint, condylar inclination values in the first condylar movement sequence demonstrated, on the average, 14.4% higher values compared to the second movement sequence, and 39.2% higher values than in the third movement sequence. For the right joint, the first condylar movement sequence demonstrated, on the average, 15.8% higher values compared to the second movement sequence, and 41.5% higher values than the third movement sequence.

CONCLUSIONS

Results suggest that condylar movement in the sagittal direction is not uniform. Mean left and mean right condylar inclination values do not necessarily describe the actual condylar path, nor do they give adequate information for articulator setup. Left-right side condylar inclination differences greater than 10 degrees can be considered as normal.

Correlation of condylar kinematics in children with gender, facial type and weight

OBJECTIVE

The aim of the study has been to describe the normal range of mandibular movements and condylar kinematics in children as well as to test the null hypothesis that these variables are not associated with gender, facial type and weight.

MATERIALS AND METHODS

The sample was comprised of 92 healthy children (7.2-10.6 years old) and 40 adult controls (18-34.7 years old). Examinations included the maximal mouth opening capacity and laterotrusion to the right and to the left. The condylar path inclination angle was calculated at 3mm and 5mm protrusion of the mandible. Kinematic variables were registered using the ultrasonic JMA system.

RESULTS

Maximal mouth opening capacity averaged 46.73 mm for the children and 53.53 mm for the adults. The mean values of the lateral movements were 9.36 mm to the right and 9.62 mm to the left for the boys, and 9.91 mm and 9.68 mm for the girls, respectively. Mean condylar path inclination in the children was 36.5° (right) and 36.2° (left) at 3mm of protrusive movement, and 34.3° (right) and 34.0° (left) at 5mm of protrusive movement. Associations of the kinematic variables with gender, weight, or facial type were insignificant.

CONCLUSION

Younger school children have not yet reached the maximum mouth-opening capacity. Correlation analysis suggests some weak, but insignificant associations of gender, facial type and weight with mouth opening, laterotrusion and the condylar path inclination angle. The null hypothesis was not rejected.

Comparison of reference points in different methods of temporomandibular joint imaging

PURPOSE

Conventional radiography is a well-established method for imaging of the temporomandibular joint (TMJ) structures. However, the dental computer tomography becomes more important for the visualization of teeth in the jaw-bone. The applicability of dental computer tomography for the visualization of the TMJ it not yet been proven. The aim of the study was to identify TMJ structures using reference points with the magnetic resonance imaging (MRI) and the computed tomography (CT).

METHODS

In order to compare the visualization and measurement of the TMJ a total of eight human cadaver heads was examined with CT and MRI and analysed using reference points.

RESULTS

In both imaging techniques the selected reference points and distances are well definable and allow objective evaluation of anatomical structures. The CT images display a clearly better contrast to noise ratio than the MR images. The distance measurement of different width and length showed significant correlation of both images techniques.

CONCLUSIONS

In TMJ diagnostics, maximum information could be obtained using both imaging techniques together due to synergistic effects.

Variations in the inclination of the condylar path in children and adults

OBJECTIVE

To test the null hypothesis that there are no differences between children and adults in the condylar path inclination angle on the right and left sides.

MATERIALS AND METHODS

A group of 80 children aged 6 to 10 years (subgroups I through V, according to chronologic age) was compared with an adult group with regard to the condylar path inclination angle (CPIA) on the right and left sides. The CPIA was measured using the ultrasonic JMA-System for registration.

RESULTS

During development of the temporomandibular joint the condylar path inclination angle increased with age in the subgroups of children. A significant difference was found in the CPIA between the groups of adults and children. In the group with the oldest children (mean age: 10.3 years) the condylar path inclination angle had reached 81.87% on the right side and 78.85% on the left side compared with the adult group at a 5 mm protrusive path. In the pooled group of children the CPIA amounted to 73.08% on the right side and 72.13% on the left side compared with the values for the adults. No significant difference was found between the right and left CPIA in any group.

CONCLUSION

The hypothesis is rejected. The CPIA on the right and left sides increased with age in the group of children and was significantly smaller in the group of children compared with the group of adults.