Changes in condylar path inclination during maximum protrusion between the ages of 6 and 12 years

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.

Designing customized temporomandibular fossa prosthesis based on envelope surface of condyle movement: validation via in silico musculoskeletal simulation

Objective: This study presents an innovative articular fossa prosthesis generated by the envelope surface of condyle movement, and compares its mandible movements, muscle activities, and joint reaction forces with two temporomandibular joint (TMJ) prostheses using multibody musculoskeletal simulation. Methods: A healthy 23-year-old female was recruited for this study. Cone-beam computed tomographic (CBCT) was performed to reconstruct the mandibular bone geometry. A customized TMJ fossa prosthesis was designed based on the subject-specific envelope surface of condyle movement (ESCM). Mandibular kinematics and jaw-closing muscle electromyography (EMG) were simultaneously recorded during maximum jaw opening-closing movements. To validate our prosthesis design, a mandibular musculoskeletal model was established using flexible multibody dynamics and the obtained kinematics and EMG data. The Biomet fossa prosthesis and the ellipsoidal fossa prosthesis designed by imitating the lower limb prostheses were used for comparison. Simulations were performed to analyze the effects of different fossa prostheses on jaw opening-closing motions, mandibular muscle activation, and contact forces. Results: The maximum opening displacement for the envelope-based fossa prosthesis was greater than those for Biomet and ellipsoidal prostheses (36 mm, 35 mm, and 33 mm, respectively). The mandibular musculoskeletal model with ellipsoidal prosthesis led to dislocation near maximal jaw opening. Compared to Biomet, the envelope-based fossa reduced the digastric and lateral pterygoid activation at maximal jaw opening. It also reduced the maximal resistance to condylar sliding on the intact side by 63.2 N. Conclusion: A customized TMJ fossa prosthesis was successfully developed using the ESCM concept. Our study of musculoskeletal multibody modeling has highlighted its advantages and potential. The artificial fossa design successfully achieved a wider condylar range of motion. It also reduced the activation of jaw opening muscles on the affected side and resistance on the intact side. This study showed that an ESCM-based approach may be useful for optimizing TMJ fossa prostheses design.

Effect of Occlusal Splint Therapy on Condylar Movements Recorded Using an Electronic Pantograph: A Prospective Clinical Study

AIMS AND OBJECTIVE

The effect of occlusal splint therapy on the muscle activity has been addressed in the literature. However, its effect on condylar movements in subjects with normal and abnormal occlusions has not yet been investigated. This prospective clinical study addressed the effect of occlusal splint therapy on condylar movements in subjects with normal and abnormal occlusions using an electronic pantograph.

MATERIALS AND METHODS

Two groups of subjects were included in this study. The first group included subjects with normal occlusion, whereas the subjects in the other group were diagnosed with abnormal occlusion. The occlusal splint was fabricated, adjusted clinically, and delivered for each subject. Condylar movements were recorded using a Cadiax Compact II electronic pantograph at baseline, 2-, 4-, and 6-month follow-up periods to assess sagittal condylar inclination (SCI), immediate mandibular lateral translation (IMLT), and progressive mandibular lateral translation (PMLT). The t-test, one-way analysis of variance (ANOVA), and two-way ANOVA were used to compare the parameters between the groups and to assess the time effect on these parameters (α = 0.05).

RESULTS

Twenty subjects were recruited for this study (n = 10). Among them, 12 were women and eight were men, with a mean age of 34 years. In each group, insignificant differences were reported for each tested parameter at baseline and during the follow-up periods (P > 0.05). However, when comparing the two groups, the only significant difference was found in the SCI during the 6-month follow-up period (P = 0.014).

CONCLUSIONS

Occlusal splints had an insignificant effect on the parameters SCI, IMLT, and PMLT up to 6 months of follow-up for subjects with normal or abnormal occlusion. SCI increased substantially in normal occlusion subjects compared with abnormal occlusion subjects during the 6-month follow-up period.

Efficacy of Kinematic Parameters for Assessment of Temporomandibular Joint Function and Disfunction: A Systematic Review and Meta-Analysis

The aim of this review was to answer the following PICO question: "Do TMJ kinematic parameters (intervention and comparison) show efficacy for assessment of mandibular function (Outcome) both in asymptomatic and TMD subjects? (Population)". PubMed, Scopus, Web of Science, Embase, Central databases were searched. The inclusion criteria were (1) performed on human, (2) English only, (3) on healthy, symptomatic or surgically altered TMJ, (4) measured dynamic kinematics of mandible or TMJ (5) with six degrees of freedom. To assess the Risk of Bias, the Joanna Briggs Institute tool for non-randomised clinical studies was employed. A pairwise meta-analysis was carried out using STATA v.17.0 (Stata). The heterogeneity was estimated using the Q value and the inconsistency index. Ninety-two articles were included in qualitative synthesis, nine studies in quantitative synthesis. The condylar inclination was significantly increased in female (effect size 0.03°, 95% CI: -0.06, 0.12, p = 0.00). Maximum mouth opening (MMO) was increased significantly in female population in comparison with males (effect size 0.65 millimetres (0.36, 1.66). Incisor displacement at MMO showed higher values for control groups compared with TMD subjects (overall effect size 0.16 millimetres (-0.37, 0.69). Evidence is still needed, considering the great variety of devices and parameters used for arthrokinematics. The present study suggests standardising outcomes, design, and population of the future studies in order to obtain more reliable and repeatable values.

Factors influencing the articular eminence of the temporomandibular joint (Review)

The temporomandibular joint (TMJ), the most complex and evolved joint in humans, presents two articular surfaces: the condyle of the mandible and the articular eminence (AE) of the temporal bone. AE is the anterior root of the zygomatic process of the temporal bone and has an anterior and a posterior slope, the latter being also known as the articular surface. AE is utterly important in the biomechanics of the TMJ, as the mandibular condyle slides along the posterior slope of the AE while the mandible moves. The aim of this review was to assess significant factors influencing the inclination of the AE, especially modifications caused by aging, biological sex or edentulism. Studies have reported variations in the angles of the slopes of the AE between medieval and recent human dry skulls, as well as between subjects of different racial origin. Recent articles have emphasized the significant role that tooth loss has on the flattening of the AE. Although some papers have described biological sex or age as factors which could be associated with differences in AE angulations, edentulism seems to be a significant factor impacting on the inclination of the AE.

Automated Real-Time Evaluation of Condylar Movement in Relation to Three-Dimensional Craniofacial and Temporomandibular Morphometry in Patients with Facial Asymmetry

The aim of this study was to investigate the correlation between craniofacial morphology, temporomandibular joint (TMJ) characteristics, and condylar functional movement in patients with facial asymmetry using an up-to-date automated real-time jaw-tracking system. A total of 30 patients with mandibular asymmetry and prognathism were included. Three-dimensional (3D) craniofacial and TMJ morphometric variables were analyzed in images captured using cone-beam computed tomography. Three-dimensional condylar movements were recorded during the opening, protrusion, and laterotrusion of the jaw and divided into those for deviated and non-deviated sides. Overall functional and morphometric variables were compared between the sides by a paired t-test. Pearson’s correlation analysis and factor analysis were also performed. As a result, significant differences were found between the sides in morphometric and functional variables. The condylar path length was significantly longer and steeper on the deviated side during protrusion and lateral excursion. TMJ morphometric asymmetry, more so than the craniofacial morphologic asymmetry, seemed to be reflected in the functional asymmetry, representing different correlations between the sides, as supported by factor analysis. This study provides evidence explaining why the asymmetric condylar path remained unchanged even after orthognathic surgery for the correction of craniofacial asymmetry.

Unilateral, Alloplastic Temporomandibular Joint Reconstruction, Biomechanically What Happens to the Contralateral Temporomandibular Joint?-A Prospective Cohort Study

PURPOSE

Unilateral alloplastic total temporomandibular joint reconstruction (TMJR) might influence the contralateral side joint function. This study's purpose was to estimate the risk for contralateral TMJR and the jaw function of the contralateral untreated temporomandibular joint (TMJ).

PATIENTS AND METHODS

A prospective cohort study design was used for patients who underwent unilateral alloplastic TMJR. The primary predictor was time after TMJR, and the secondary predictors were pre-TMJR mandibular angle resection, prior ipsilateral TMJ surgeries, and TMJR design (custom, stock). The primary outcome variable was the need for contralateral TMJR. The secondary outcome variables were the results of jaw function-jaw tracking, maximum voluntary clenching, surface electromyography, and pressure pain thresholds (PPT) and patient's quality-of-life (oral health-related quality-of-life [OHrQoL]). Data were collected preoperatively (T0), and 1 year (T1), 2-3 years (T2), and ≥ 4 years postoperatively (T4). Analysis of variance with post hoc Tukey -HSD test and multiple linear regression analysis were used for statistical analysis. P < .05 was considered significant.

RESULTS

Thirty-nine patients were enrolled, 15 males and 24 females, with an average age of 48.9 ± 16.2 years. Two patients (5.1%) required a contralateral TMJR. Contralateral condylar motion, incisal laterotrusion, and protrusion slightly decreased, while incisal opening (P = .003), rotation angle (P = .013), opening deflection, surface electromyography activity, maximum voluntary clenching (P = .01), PPTs, and OHrQoL all increased. Pre-TMJR mandibular angle resection had an impact on PPTs and subjective outcomes and prior ipsilateral TMJ surgeries on the opening rotation angle.

CONCLUSIONS

Based on this study, bilateral TMJR does not appear necessary when the contralateral TMJ is healthy. Unilateral alloplastic TMJR is associated with improved contralateral jaw function and OHrQoL.

Measurement of normal and pathological mandibular and temporomandibular joint kinematics: A systematic review

Motion of the mandible and temporomandibular joint (TMJ) plays a pivotal role in the function of the dentition and associated hard and soft tissue structures, and facilitates mastication, oral communication and access to respiratory and digestive systems. Quantification of TMJ kinematics is clinically relevant in cases of prosthetic rehabilitations, TMJ disorders, osteoarthritis, trauma, tumour resection and congenital abnormalities, which are known to directly influence mandibular motion and loading. The objective of this systematic review was to critically investigate published literature on historic and contemporary measurement modalities used to quantify in vivo mandibular and TMJ kinematics in six degrees of freedom. The electronic databases of Scopus, Web of Science, Medline, Embase and Central were searched and 109 relevant articles identified. Publication quality was documented using a modified Downs and Black checklist. Axiography and ultrasonic tracking are commonly employed in the clinical setting due to their simplicity and capacity to rapidly acquire low-fidelity mandibular motion data. Magnetic and optoelectronic tracking have been used in combination with dental splints to produce higher accuracy measurements while minimising skin motion artefact, but at the expense of setup time and cost. Four-dimensional computed tomography provides direct 3D measurement of mandibular and TMJ motion while circumventing skin motion artefact entirely, but employs ionising radiation, is restricted to low sampling frequencies, and requires time-consuming image processing. Recent advances in magnetic tracking using miniature sensors adhered to the teeth in combination with intraoral scanning may facilitate rapid and high precision mandibular kinematics measurement in the clinical setting. The findings of this review will guide selection and application of mandibular and TMJ kinematic measurement for both clinical and research applications.

Computerized ultrasonic axiographic evaluation of condylar movement in patients with internal derangement of the temporomandibular joint

OBJECTIVES

To evaluate condylar movement during lateral excursion in individuals with internal derangement of the temporomandibular joint (TMJ) using ultrasonic axiography.

MATERIALS AND METHODS

A total of 34 patients with internal derangement of the TMJ and 34 participants in the control group were examined. Mandibular functional movement was recorded by ultrasonic axiography. Three-dimensional condylar movement was measured in the working and balancing condyles.

RESULTS

Significant differences in condylar movement were found between the two groups. In the group with internal derangement of the TMJ, the three-dimensional linear distances of the condylar path in a working condyle were greater than in the control group during lateral excursion. The speed of the balancing condyle in the returning path of lateral excursion was significantly greater in the group with internal derangement than in the control group.

CONCLUSIONS

The results of the present study indicate that internal derangement of TMJ may affect the working and balancing condylar movements during lateral excursion.

The influence of the human TMJ eminence inclination on predicted masticatory muscle forces

Aim of this paper was to investigate the change in masticatory muscle forces and temporomandibular joint (TMJ) reaction forces simulated by inverse dynamics when thesteepness of the anterior fossa slope was varied. We used the model by de Zee et al. (2007) created in AnyBody™. The model was equipped with 24musculotendon actuators. Mandibular movement was governed by thetrajectory of theincisal point. The TMJ was modelled as a planar constraint canted 5°medially and thecaudal inclination relative to the occlusal plane was varied from 10° to 70°. Our models showed that for the two simulated movements (empty chewing and unilateral clenching) the joint reaction forces were smallest for the eminence inclination of 30° and 40° and highest for 70°. The muscle forces were relatively insensitive to change of the eminence inclination for the angles between 20° and 50°. This did not hold for the pterygoid muscle, for which the muscle forces increased continually with increasing fossa inclination. For empty chewing the muscle force reached smaller values than for clenching. During clenching, the muscle forces changed by up to 200N.

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.

The influence of different registration techniques on condyle displacement and electromyographic activity in stomatognathically healthy subjects: a prospective study

STATEMENT OF PROBLEM

It is unclear whether different intermaxillary registration techniques are related to a physiological condylar position that permits neuromuscular equilibrium.

PURPOSE

This study analyzes and quantifies the effects of different registration techniques on the condyle position and how the registration technique modulates bilateral masseter and anterior temporalis muscle electromyographic activity.

MATERIAL AND METHODS

Three-dimensional electronic condylar position analysis (EPA) with an ultrasound-based jaw-tracking system and surface electromyographic activity (sEMG) was recorded during the registration of a manually guided centric relation (CR), maximal intercuspation (MI), and Gothic arch tracing guided centric relation (DIR method). Participants were 26 stomatognathically healthy volunteers (mean age, 30.6 ±9.5 years). Data were analyzed by 1-way ANOVA and post hoc Bonferroni correction (α=.05).

RESULTS

EPA showed significant differences (P<.001) for CR, MI, and DIR in the vertical, sagittal, and horizontal axes. The condyle position during DIR was found to be significantly more anteriorly and inferiorly located than with CR (P<.001) and MI (P<.04). There were no significant differences in the mean muscle activity among CR, MI, and DIR. Muscular symmetry ranged from 63.87 to 81.47%. Significantly higher symmetry for the anterior temporalis (P=.03) and the masseter (P=.03) was found during the DIR than with CR. Torque coefficients (potential laterodeviating effect) were between 88.02% (CR) and 89.94% (MI).

CONCLUSIONS

Registration technique significantly influenced the condyle position, while mean muscular activity was minimally affected. With respect to muscular balance and activation, the DIR position proved to be capable of inducing the greatest motor unit activity when compared with manually guided CR and MI.

Longitudinal observation of mandibular motion pattern in patients with skeletal Class III malocclusion subsequent to orthognathic surgery

PURPOSE

The aims of the present study were to delineate the characteristic patterns of 3-dimensional (3D) mandibular movement in patients with skeletal Class III malocclusion compared with normal individuals and to investigate the longitudinal changes in mandible and condylar motion after orthognathic surgery (OGS).

PATIENTS AND METHODS

The subjects in the present prospective study consisted of 2 groups. The OGS group included 24 patients with skeletal Class III who underwent OGS. The control group consisted of 25 patients who underwent orthodontic treatment only. The patient records included demographic data, lateral and posteroanterior cephalometric radiographs before treatment, and serial mandibular motion data. In the OGS group, the mandibular motion data were obtained before OGS (T1), 1 month after OGS (T2), and at least 6 months after OGS (T3). The differences in cephalometric measurements and mandibular movements between the 2 groups were compared. The Pearson correlation test was performed to assess the relationship between the cephalometric measurements and the mandibular movements. Serial changes in mandibular movement in the OGS group were also compared.

RESULTS

The skeletal pattern in the OGS group demonstrated retrusive maxilla and a protrusive mandible, with a larger mandibular plane angle. For the incisal range of motion, the OGS group's maximal mouth opening was larger than the control group's by 6.9 mm. In the OGS group, the condylar range of motion in retrusion and the Bennett angle were asymmetric. Skeletal Class III patients tended to have a smaller range of condylar retrusion. At 1 month after OGS, the maximal incisal range of motion decreased from 57.23 to 25.61 mm. Other variables, including laterotrusion, movement velocity, and angle and distance of condylar movement in protrusion, reduced significantly. The Bennett angle demonstrated increased symmetry on both sides. Six months after OGS, the condylar motion in opening demonstrated improvements, but to a lesser extent than at T1. The condylar motion in retrusion recovered totally. The maximum incisal range of motion reduced slightly, but remained similar in value to that of the control group. The variables, including laterotrusion, movement velocity, and angle and distance of condylar movement in protrusion, demonstrated total recovery. The mandibular movement variables at T3 were not significantly different from those of the control group.

CONCLUSIONS

Skeletal Class III patients demonstrated a larger maximal mouth opening than did the controls, along with similar laterotrusion, but with a smaller retrusive condylar range of movement. The range of incisor motion and condylar movement did not correlate. The deterioration in mandibular motion after OGS can recover totally within 6 months. At T3, the mandibular movement remained consistent with the amount in normal subjects.

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.

Growth-related differences in maximum laterotrusion and retrusion between children and adults

OBJECTIVE

To test the null hypothesis that there are no differences between children and adults in maximum laterotrusion and maximum retrusion on the right and left sides.

MATERIALS AND METHODS

This population-based study included 81 randomly selected children between the ages of 6 and 10 years and 67 adults. Kinematic variables were measured with the ultrasonic JMA-System for registration.

RESULTS

The mean maximum laterotrusion of the children's group (10.6 +/- 1.5 mm on the left, 11.0 +/- 1.7 mm on the right) was significantly smaller than that of the adult group (11.7 +/- 2.0 mm on the left, 12.2 +/- 1.7 mm on the right). The maximum laterotrusion of the children's group corresponded to about 90% on the left and right sides of that of the adult group. The mean maximum retrusion of the children's group was significantly bigger than that of the adult group. There, the adult values corresponded to 66.7% on the left and 50% on the right side of the children's values. No significant difference in maximum laterotrusion and retrusion was noted on the right and left sides, and no significant differences according to gender specificities were observed in either group.

CONCLUSIONS

The hypothesis is rejected. In development of the temporomandibular joint, maximum laterotrusion on the right and left sides increases significantly with age, and maximum retrusion decreases significantly with age.