Mandibular movement and frontal craniofacial morphology in orthognathic surgery patients with mandibular deviation and protrusion

Tongue pressure and maxillofacial muscle activities during swallowing in patients with mandibular prognathism

BACKGROUND

Coordination among lip, cheek and tongue movements during swallowing in patients with mandibular prognathism remains unclear.

OBJECTIVES

This study aimed to identify the temporal sequences of tongue pressure and maxillofacial muscle activities during swallowing in patients with mandibular prognathism and compared characteristics with those of healthy volunteers.

METHODS

Seven patients with mandibular prognathism (mandibular prognathism group) and 25 healthy volunteers with individual normal occlusion (control group) were recruited. Tongue pressures and masseter, orbicularis oris, mentalis and supra- and infrahyoid muscle activities while swallowing gel were measured simultaneously using a sensor sheet system with five measurement points and surface electromyography, respectively. Onset time, offset time and durations of tongue pressure and muscle activities were analysed.

RESULTS

In the mandibular prognathism group, tongue pressure was often produced first in more peripheral parts of the palate. Offset of tongue pressure in the posteromedian and peripheral parts of the palate and maxillofacial muscle activities except for orbicularis oris were delayed. Duration of tongue pressure in the anteromedian part of the palate was significantly shorter and durations of masseter, mentalis and suprahyoid muscle activities were significantly longer. Times to onset of orbicularis oris and suprahyoid muscle activities based on first onset of tongue pressure were significantly shorter.

CONCLUSION

These results suggest that patients with mandibular prognathism may exhibit specific patterns of tongue pressure production and maxillofacial muscle activities during swallowing.

Disc Displacement of the Temporomandibular Joint and Facial Asymmetry in Children and Adolescents: A Systematic Review and Meta-Analysis

Subjects with facial skeletal asymmetries have a higher incidence of anterior temporomandibular joint disc displacement. The objective of the study was to consolidate existing evidence on the connection between temporomandibular joint disc displacement and mandibular asymmetry in youngsters and adolescents. A thorough examination was undertaken in the following databases: PubMed, Scopus, EMBASE, Web of Science, and Cochrane. To judge the publications’ methodological quality Newcastle Ottawa Scale was used. From the 1011 identified records, eight were selected for the qualitative synthesis and five for the quantitative synthesis, amounting to 692 subjects. Fifteen cephalometric variables were meta-analyzed. The distance from menton (Me) to midline (lateral mandibular asymmetry) was significantly shorter [−1.75 (95% CI −2.43–−1.07), p ≤ 0.001] in subjects with disc displacement compared to those without disc displacement. The distance from articulare (Ar) to gonion (Go) was significantly longer [3.74 (95% CI 1.04–6.44), p = 0.007] in subjects with disc displacement compared to those without disc displacement. The relationship between distance from articulare (Ar) to gonion (Go) or sella (S) to gonion (Go) and disc displacement was shown to be close to statistical significance level, but not for other cephalometric data. Disc displacement was associated with several cephalometric measurement variations in children and adolescents.

Correlation between the position of the glenoid fossa and condylar translational movement in skeletal Class III mandibular asymmetry patients

OBJECTIVES

Understanding the mechanism of mandibular asymmetry (MA) is important to provide suggestions for occlusal treatment and to know the developmental process of masticatory dysfunction. To investigate the morphological and functional effects on MA, we evaluated the three-dimensional position of the glenoid fossa and its relationship to asymmetrical condylar translational movement.

METHODS

In this retrospective study, 50 subjects who previously underwent computed tomography for surgical purposes were divided into MA and control groups according to a menton deviation of at least 4 mm from the mid-sagittal plane. The glenoid fossae positions were evaluated using a three-dimensional analysis program. Condylar translational movements were recorded and measured by computerized axiography on protrusion. Side-to-side asymmetry was measured for each parameter. Asymmetry index value was calculated to assess the correlation between glenoid fossa position and condylar movement. Wilcoxon's signed-ranked test, Mann-Whitney U-test, and Spearman's rank correlation were used for the statistical analysis.

RESULTS

In the MA group, glenoid fossa position on the shifted side was significantly inferior and posterior as compared to that on the non-shifted side and of the control group. Condylar path length and sagittal condylar inclination were significantly greater on the shifted side versus non-shifted side, while no significant difference was found in transverse condylar inclination. The asymmetry index of the anterior-posterior glenoid fossa position was significantly correlated with that of condylar path length and bilateral transverse condylar inclination. In the control group, there were no significant correlations among the morphological and functional parameters.

LIMITATIONS

This study did not consider muscle activity and disc position, which may affect condylar movement.

CONCLUSIONS

Functional asymmetry of condylar translational movements is closely related to asymmetry of glenoid fossa position in MA patients.

Stomatognathic functional improvement in a patient with a canted occlusal plane and temporomandibular disorder treated with an edgewise appliance and miniscrews

Generally, a canted occlusal plane results in esthetic problems, such as an asymmetric mandible with midline deviation, and functional problems, such as temporomandibular disorder (TMD). For many years, orthognathic surgery has been used to level a canted occlusal plane. However, similar effects might be achieved by intruding the posterior teeth using a miniscrew. This case report describes a patient with a canted occlusal plane, mandibular deviation, shifted dental midlines, and TMD treated with an edgewise appliance using miniscrews as anchorage. Vertical control of posterior teeth with miniscrews enabled flattening of the canted occlusal plane. Dental midlines were coincided with the midfacial line, thereby improving smile symmetry. During 4 years of retention, the patient maintained ideal occlusion. Furthermore, TMD symptoms disappeared, and significant improvements in stomatognathic functions were observed compared with those at pretreatment. These results suggest that miniscrews can be used to improve canted occlusal plane and stomatognathic malfunctions.

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.

Reliability in Mandibular Movement Evaluation Using Photogrammetry in Patients With Temporomandibular Disorders

OBJECTIVE

The purpose of this study was to propose a quantitative evaluation for mandibular opening-closing movement asymmetries and to verify the intraexaminer and interexaminer reliability using photogrammetry in individuals with and without myogenic temporomandibular disorders.

METHODS

Forty-nine female participants between ages 18 and 40 were enrolled in this study. They were assigned to 2 different groups: a temporomandibular disorder group, (n = 25; 28.1 ± 3.6 years) and an asymptomatic group (n = 24; 25.6 ± 5.1 years). Data were collected through photogrammetry using Corel Draw X3 software (Corel Corp, Ottawa, Ontario, Canada) for angle measurements. Reliability analysis was done on the total sample, and the photographs were obtained by a singular examiner on 2 occasions (intraexaminer) 1 month apart and from measurement made by another examiner (interexaminer) on different days. The intraclass correlation coefficient (ICC) was applied with a significance level of 5%.

RESULTS

The photogrammetry had excellent intrarater and inter-rater reliability for the evaluation of opening and closing movements of the jaw (intrarater: opening ICC = 0.99; closing ICC = 0.98; inter-rater: opening ICC = 0.89 and closing ICC = 0.82). Photogrammetry also demonstrated excellent intra- and inter-rater reliability in the evaluation of head posture (intra-rater: head deviation ICC = 0.96; head position ICC = 0.75; inter-rater: head deviation ICC = 0.98; head position ICC = 0.98).

CONCLUSION

Under these experimental conditions, most angular values presented excellent intra- and interexaminer reliability.

Orthognathic surgery induces genomewide changes longitudinally in DNA methylation in saliva

OBJECTIVE

Orthognathic surgery dramatically changes morphology of the maxillofacial deformity and improves the malocclusion morphologically and functionally. We investigated the influence of orthognathic surgery on genomewide DNA methylation in saliva.

METHODS

Saliva was obtained from nine patients undergoing orthognathic surgery and two healthy reference individuals before and 3 months after orthognathic surgery. Genomewide DNA methylation profiling of saliva (341,482 CpG dinucleotides) was conducted using Infinium HumanMethylation450 BeadChips.

RESULTS

Comparison between pre- and postsurgery saliva samples revealed significant changes in DNA methylation patterns at 2,381 CpG sites (p < 0.01) with suggestive significance. The differentially methylated probe sets were significantly associated with the cancer pathway (p = 2.8 × 10^-7 ; a false discovery rate q-value = 3.7 × 10^-4 ) and PI3K-Akt signalling pathway (p = 2.4 × 10^-5 ; a false discovery rate q-value = 3.1 × 10^-2 ).

CONCLUSION

Pathway enrichment analysis of genes with suggestive significance demonstrated that altered DNA methylation in saliva of patients undergoing orthognathic surgery, possibly as a response to surgical stress or bone injury. Further studies with a large sample size and long-term observation are needed to validate the phenomena identified in this study.

Three-dimensional mandibular motion in skeletal Class III patients

OBJECTIVE

The aim of the study was to analyze the characteristics and changes in mandibular condylar motion in patients with skeletal Class III malocclusion.

METHODS

Using a 3D motion analyzer, mandibular movements were recorded in 9 patients with skeletal Class III malocclusion and 22 control subjects with Angle Class I jaw relationships.

RESULTS

Class III patients had a similar interincisor point displacement but a significantly reduced displacement of both condyles on the sagittal and frontal planes, with smaller translation paths than control subjects (right -9.4 mm; left -4.8 mm). The overall condylar rotation component was larger in Class III patients (right +8.8%; left +7.3%). The largest inter-group significant differences were observed in the first 10% of mouth opening, in which Class III patients had a larger rotating component than control subjects (+20%, p < 0.01).

CONCLUSIONS

Condylar motion was reduced in skeletal Class III patients, in particular in the translational path.

Improvement of asymmetric stomatognathic functions, unilateral crossbite, and facial esthetics in a patient with skeletal Class III malocclusion and mandibular asymmetry, treated with orthognathic surgery

Patients with a dentofacial skeletal deformity have not only esthetic and morphologic problems related to facial proportions and dentition, but also problems of stomatognathic functions. Therefore, in addition to morphologic analysis, functional analysis is important for the diagnosis and evaluation of treatment in these patients. However, no reports have described longitudinal simultaneous evaluations of stomatognathic functions, and the comprehensive effects of surgical orthodontics on the stomatognathic functions are unclear. A patient was diagnosed as having a skeletal Class III jaw-base relationship, mandibular asymmetry, unilateral crossbite, asymmetric stomatognathic functions, and a temporomandibular disorder. She was treated with a combination of surgery and orthodontic therapy. As a result, facial proportions and occlusion improved; in particular, asymmetric stomatognathic functions, including masticatory muscle activity, condylar movement, and occlusal force, became symmetric between the left and right sides. Moreover, after 2 years of retention, the activity of the masticatory muscles and the values of occlusal force and occlusal contact area exceeded those at pretreatment. These results suggest that improvement of asymmetric stomatognathic functions can be achieved by correction of dentofacial morphology by surgical orthodontic treatment in patients with mandibular asymmetry.

A correlational study of scoliosis and trunk balance in adult patients with mandibular deviation

Previous studies have confirmed that patients with mandibular deviation often have abnormal morphology of their cervical vertebrae. However, the relationship between mandibular deviation, scoliosis, and trunk balance has not been studied. Currently, mandibular deviation is usually treated as a single pathology, which leads to poor clinical efficiency. We investigated the relationship of spine coronal morphology and trunk balance in adult patients with mandibular deviation, and compared the finding to those in healthy volunteers. 35 adult patients with skeletal mandibular deviation and 10 healthy volunteers underwent anterior X-ray films of the head and posteroanterior X-ray films of the spine. Landmarks and lines were drawn and measured on these films. The axis distance method was used to measure the degree of scoliosis and the balance angle method was used to measure trunk balance. The relationship of mandibular deviation, spine coronal morphology and trunk balance was evaluated with the Pearson correlation method. The spine coronal morphology of patients with mandibular deviation demonstrated an "S" type curve, while a straight line parallel with the gravity line was found in the control group (significant difference, p<0.01). The trunk balance of patients with mandibular deviation was disturbed (imbalance angle >1°), while the control group had a normal trunk balance (imbalance angle <1°). There was a significant difference between the two groups (p<0.01). The degree of scoliosis and shoulder imbalance correlated with the degree of mandibular deviation, and presented a linear trend. The direction of mandibular deviation was the same as that of the lateral bending of thoracolumbar vertebrae, which was opposite to the direction of lateral bending of cervical vertebrae. Our study shows the degree of mandibular deviation has a high correlation with the degree of scoliosis and trunk imbalance, all the three deformities should be clinically evaluated in the management of mandibular deviation.

Correlation between 3-dimensional facial morphology and mandibular movement during maximum mouth opening and closing

PURPOSE

The purpose of this study was to analyze the relationship between mandibular movement and facial morphology parameters measured using 3-dimensional CT data.

MATERIALS AND METHODS

We have developed a mandibular movement tracking and simulation system. The mandibular movement data were acquired from 22 subjects (6 males and 16 females), 3 who had no clinical facial deformities and 19 who had orthofacial deformities. The subjects voluntarily performed maximum mouth opening and closing movements. Three-dimensional maximum linear movements of selected points (bilateral condylions, infradentale, and pogonion) were calculated to represent mandibular movement. Facial morphology values were measured 3-dimensionally from CT data and bilateral morphological values were divided into 2 groups according to the mandibular deviation, the deviated side, and counter-deviated side groups. Correlation coefficients were calculated to evaluate the relationship between mandibular movements and facial morphology.

RESULTS

Maximum linear movements of all selected points on the mandible were positively correlated with sella-nasion-point A (SNA) and sella-nasion-point B (SNB). Movements of the infradentale and pogonion were significantly correlated with ramus inclination, lateral mandibular body angle, ramus length, and mandibular body length. Condylar movement was positively correlated with lateral mandibular body angle and mandibular body length. Multiple stepwise linear regression analysis was performed to evaluate the model predicting the effect of morphological values on mandibular movement. Condylar movement was associated with the SNA (R(2) value = 0.32 for the deviated side, R(2) value = 0.26 for the counter-deviated side), and movement of the infradentale was associated with both SNA and ramus length (R(2) value = 0.57). Movement of the pogonion could be predicted by SNA, mandibular length, and condylar head length (R(2) value = 0.65).

CONCLUSION

The 3D facial morphology values were associated with variations in mandibular movement, and morphological parameters contributed to predicting the movement of the mandible with different degrees.

Postsurgical Orthodontic Treatment Planning: a Case Report with 20 Years Follow-up

Background

Traditionally, maxillofacial deformities are corrected surgically after an initial orthodontic treatment phase. However in, this article, the authors emphasize the postsurgical therapeutic protocol which is extremely important for determining the final and permanent retention of the corrected occlusion.

Methods

A 55 year old female with severe skeletal Class II malocclusion is presented. Combined surgical and orthodontic correction of the malocclusion was used.

Results

: The step-by-step procedure the authors followed for the postsurgical therapy is described. The goals of the postoperative therapy were to restore and rehabilitate neuromuscular function, obtain occlusal stabilization, grind teeth selectively, and final occlusion retention. The importance of a surgical occlusal splint for rehabilitating stomatognathic neuromuscular function postoperatively was demonstrated. Furthermore, the orthodontic-prosthodontic treatment ensured occlusion stability after the surgical correction. The long-term results confirmed the efficacy of the treatment protocol presented here from both functional and aesthetical perspectives.

Conclusions

Postsurgical orthodontic treatment is an important step in the surgical and orthodontic therapy of maxillofacial deformities.

Development of a novel statistical model for mandibular kinematics

The purpose of this study was to establish a new statistical method for the analysis of masticatory function. The subjects were patients with anterior crossbite who had received orthognathic surgery. Chewing movement was measured by means of an opto-electronic motion-analysis system. This movement was compared with similar movement in control patients. We sought to develop a statistical model to predict the population average curves of the chewing cycles. In this study, the mandibular incisor point was used as a target point of jaw movement. The combination of a spline function with random coefficients and self-modeling regression (SEMOR) extended to three dimensions was used to predict population average curves for each group. Unquestionably, significant differences were present in some areas. The present modeling method that uses the combination of a spline function and SEMOR is one of the best ways to eliminate subjective estimation with regard to predicting representative chewing cycles.

Differential diagnosis of the idiopathic laterally deviated mandible

SUMMARY

Among patients who present for an orthognathic evaluation, a common finding is the presence of a laterally deviated mandible. At times, there is a cause to which the lower face asymmetry can be attributed, such as personal history of trauma to the face, presence of congenital disease known to affect the mandible, or other developmental abnormalities. More commonly, however, the patient is underdiagnosed and the cause of the idiopathic, laterally deviated mandible may be perplexing. The authors review the common causes of lateral deviation of the mandible and discuss how the growth of the mandible is affected and how the correct diagnosis may be ascertained. Among the common diagnoses, there are two major categories of mandibular asymmetry: (1) altered cranial base (e.g., muscular torticollis, unilateral craniosynostosis, and deformational plagiocephaly) and (2) condylar abnormality (e.g., condylar fractures, condylar hyperplasia, juvenile condylar arthritis, and hemifacial microsomia). Proper diagnosis and subsequent treatment of the underlying abnormality of the deviated mandible ensure the patient of the appropriate orthognathic reconstruction and decrease the likelihood of skeletal relapse after surgery.

[Diagnosis and therapy of adult patients with facial asymmetry]

The goal of orthodontic treatment is to improve the patient's life by enhancing dental and jaw functions and dentofacial esthetics [Graber TM, et al., Orthodontics current principles and techniques. 4(e) ed. St Louis: Elsevier, 2005.]. Harmonious occlusion is achieved following improvements of malocclusion via orthodontic treatment [Ehmer U and Broll P, Int J Adult Orthod Orthognath Surg 1992;7:153-159. Throckmorton GS, et al., J Prosthet Dent 1984;51:252-261.]. Perfect facial symmetry is extremely rare, and normal faces have a degree of asymmetry. Patients with dentofacial deformity more frequently have asymmetry of the face and jaws. There was a relationship between the type of malocclusion and the prevalence of asymmetry; 28% of the Class III group, but 40% to 42% of the Class I, Class II and long face groups respectively, were asymmetric [Severt TR and Proffit WR, Int J Adult Orthod Orthogn Surg 1997;12:171-176.]; therefore, facial asymmetry is a common complaint among orthodontic patients. Treatment of severe facial asymmetry in adults consists mainly of surgically repositioning the maxilla or the mandible [Bardinet E, et al., Orthod Fr 2002;73:243-315. Guyuron B, Clin Plast Surg 1989;16:795-801. Proffit WR, et al., Contemporary treatment of dentofacial deformity. 2003. St Louis: Mosby, 2003:574-644.], however, new methods, i.e. orthodontic tooth movement with implant anchorage, have recently been introduced [Costa A, et al., Int J Adult Orthod Orthognath Surg 1998;3:201-209. Creekmore TD and Eklund MK, J Clin Orthod 1983;17:266-269. Miyawaki S,et al., Am J Orthod Dentofacial Orthop 2003;124:373-378. Park HS, et al., J Clin Orthod 2001;35:417-422. Roberts WE, et al., Angle Orthod 1989;59:247-256.], and various treatment options can be chosen in patients with facial asymmetry. In this article, we describe the diagnosis and treatment of adult patients with facial asymmetry.

Changes in the chewing path of patients in skeletal class III with and without asymmetry before and after orthognathic surgery

PURPOSE

The purpose of this study was to examine the relation between changes in the condylar long axis and the chewing path before and after mandibular ramus osteotomy for patients with prognathism with and without asymmetry.

PATIENTS AND METHODS

Eleven men and 16 women with mandibular prognathism were divided into groups on the basis of symmetry and osteotomy procedure. Preoperative and postoperative frontal chewing paths were recorded. The chewing path consisted of 4 components: deviated side range, undeviated side range, vertical range, and incisal path angle. The angle of the condylar long axis and the 4 components of the chewing path were compared between groups and the differences were analyzed statistically.

RESULTS

No significant differences in each of the 4 chewing path components were found between groups on the basis of symmetry or osteotomy procedure. A positive correlation was found between the changes in incisal path angle when chewing on the undeviated side and condylar long axis angle on the undeviated side (P < .05). A positive correlation was also found between the changes in undeviated side range when chewing on the deviated side and condylar long axis angle on the deviated side (P < .05).

CONCLUSION

This study suggests that surgically induced increase in the condylar long axis is correlated with increase in side range and incisor path angle, although surgical orthodontic treatment does not significantly change the chewing pattern.