Mandibular Rotation Research Articles

The mandibular rotations were not roll or yaw in facial bone asymmetry patients

Background: The mandibular rotation has been described as roll or yaw with relation to the midface. However, little is known regarding how the mandible rotates in clinical cases. Objectives: The purposes of this report were to locate the rotational axis of the mandible in facial asymmetry patients. Methods: A retrospective review was conducted on 60 facial asymmetry patients. They all underwent computed tomography (CT) examination for symmetry analysis. Optimal symmetry planes (OSPs) of the midface and the mandible were generated by computing the CT data of the structures. The mandibular rotation was broken down into the frontal and the horizontal rotation. Connection of the two rotational centres was the mandibular rotation axis. The rotational centre was measured from the point where the midface OSP met the lower chin border (FC) and the frontal rotational centre distance (FRCD) and the horizontal rotational centre distance (HRCD) were recorded. Findings and Conclusion: Analysis results showed that the rotational axes highly varied in its location. The median FRCD was 126.1 mm (range, −195.9 to 2304.1 mm) and the median HRCD was 153.4 mm (range, −110.3 to 2942.7 mm). There was no significant difference between the FRCD and HRCD (P = 0.855). Because of the highly variable location of the axes, the mandibular rotations could hardly be categorised as roll, yaw or a combination of them, which is defined as rotation around the geographic centre of the structure. As a result, de-rotation of the mandible would be difficult without using the OSPs as guides.

Dentofacial changes after anterior crossbite correction using a lingual arch with finger springs

Background/purposeAnterior crossbite correction is common in orthodontic treatment; however, few studies have discussed the change with cephalometric measurements. The purpose of this study was to evaluate the dentofacial changes in anterior crossbite correction by using an upper lingual arch with finger springs. Materials and methodsThis retrospective study included 30 patients (13 female and 17 male). According to the number of crossbite teeth, the patients were divided into three groups. We used paired t test, Kruskal–Wallis test, Mann–Whitney U test, and multiple regression analysis to perform statistical analysis. ResultsAccording to overall treatment changes, the dental changes included overjet increase, overbite decrease, upper incisor proclination, lower incisor retroclination and intrusion, upper molar distal tipping with extrusion, and lower molar intrusion. These dental changes resulted in clockwise mandibular rotation and lip position change. Anterior crossbite correction did not require increasing bite appliances. According to multiple regression analysis, the change in overjet was associated with the position of the upper and lower incisor crown tips. The mean rate of upper incisor movement in the horizontal direction was 2.5 mm/mo. The treatment duration exhibited no significant difference among the three groups. ConclusionLingual arch with finger springs was effective in anterior crossbite correction regardless of the number of crossbite teeth.

Mandibular and glenoid fossa changes after bone-anchored maxillary protraction therapy in patients with UCLP: A 3-D preliminary assessment.

To assess mandibular and glenoid fossa (GF) changes after bone-anchored maxillary protraction (BAMP) therapy in patients with unilateral complete cleft lip and palate (UCLP). The cleft group (CG) comprised 19 patients with (mean initial age of 11.8 years). The noncleft group (NCG) comprised 24 patients without clefts (mean initial age of 11.7 years). Both groups had Class III malocclusion and were treated with BAMP therapy for 18 and 12 months, respectively. Cone-beam computed tomography (CBCT) exams were performed before and after treatment and superimposed on the anterior cranial fossa (ACF). Mandibular rotations and three-dimensional linear displacements of the mandible and GF were quantified. A t-test corrected for multiple testing (Holm-Bonferroni method) and a paired t-test were used to compare, respectively, the CG and NCG and cleft vs noncleft sides (P < .05). Immediately after active treatment, the GF was displaced posteriorly and laterally in both groups relative to the ACF. The overall GF changes in the CG were significantly smaller than in the NCG. Condylar displacement was similar in both groups, following a posterior and lateral direction. The gonial angle was displaced similarly posteriorly, laterally, and inferiorly in both groups. The intercondylar line rotated in opposite directions in the CG and NCG groups. In the CG, most changes of the GF and mandible were symmetrical. Overall GF and mandibular changes after BAMP therapy were similar in patients with and without clefts. The exception was the posterior remodeling of the GF that was slightly smaller in patients with UCLP.

Displacement of the Mandibular Condyles Immediately after Herbst Appliance Insertion - 3D Assessment.

To test the following two hypotheses regarding the consequences of Herbst appliance (HA) insertion: 1) a significant clockwise mandibular rotation will occur and 2) the displacement of the condyles will follow the same magnitude of the changes of overjet (OJ) and overbite (OB). Virtual 3D surface models of 25 patients were generated from cone-beam computed tomographs taken before treatment and immediately after HA insertion. Scans were registered on the cranial base and were analyzed using point-to-point measurements, color-coded maps, and semitransparent overlays. Statistical tests included correlation and simple regression analysis. Pitch rotation, ranging from -2.2° to 2.2° (mean, 0.2°), was observed in clockwise and counterclockwise directions. Condylar sagittal displacement presented a positive correlation with OJ changes. Each millimeter of OJ correction resulted in an anterior condylar displacement of approximately 0.95 mm. Vertical condylar displacement correlated with OB changes and varied mostly between 2 mm and 4.5 mm. Immediately after HA insertion, no significant clockwise mandibular rotation was observed. The condyles were displaced anteriorly and inferiorly. Condylar anterior displacement and OJ correction presented a ratio close to 1:1. The vertical displacement of the condyles did not follow the same magnitude of OB changes.

Long-term outcomes of mandibular kinematics following class II malocclusion therapy with removable functional appliance therapy

Objective: To evaluate mandibular kinematics in class I adults following class II therapy with removable functional appliances (RFAs) during the growth period in comparison with orthodontically untreated class I and II individuals.Methods: Condylar (CRoM) and incisal range of motion (InRoM), velocity during opening and closing, and the mandibular rotation angle were recorded using an ultrasound-based jaw-tracking system in 36 test patients (mean age = 28.03 ± 6.58 years).Results: Significant group effects were found for CRoM towards the posterior in the right joint (p = 0.002) and InRoM towards the anterior (p = 0.043). The post hoc Tukey test indicates a significantly longer CRoM (posterior) for the right condyle in class II (p = 0.003) and RFA individuals (p = 0.023).Discussion: The kinematic data imply greater dentoalveolar effects due to RFA therapy than adaptive remodeling of the temporomandibular joint. The class I relationship in the RFA group following treatment indicates stable long-term outcomes.

Effect of molar intrusion with temporary anchorage devices in patients with anterior open bite: a systematic review.

ObjectiveThe objective of the study is to assess the effect of molar intrusion with temporary anchorage devices on the vertical facial morphology and mandibular rotation during open bite treatment in the permanent dentition.MethodsWe performed a systematic review of the published data in seven electronic databases up to September 2015. We considered studies for inclusion if they were examining the effects of posterior teeth intrusion on the vertical facial morphology with open bite malocclusion in the permanent dentition. Study selection, risk of bias assessment, and data-extraction were performed in duplicate. Meta-analysis was not possible due to dissimilarity and heterogeneity among the included studies.ResultsOut of the 42 articles that met the initial eligibility criteria, 12 studies were finally selected. Low level of scientific evidence was identified after risk of bias assessment of the included studies with no relevant randomized controlled trial performed. Out of the 12 selected studies, five studies used miniplates and seven studies used miniscrews. Mandibular counterclockwise rotation was found to be between 2.3° and 3.9° in six studies (as sassed by mandibular plane angle, between MeGo or GoGn and SN or FH plane) while it was less than 2° in the remaining studies.ConclusionsCurrent weak evidence suggests that molar intrusion with temporary anchorage devices may cause mandibular counterclockwise autorotation. Future well-conducted and clearly reported multicenter randomized controlled trials that include a non-treatment control group are needed to make robust recommendations regarding the amount of mandibular rotation during open bite treatments.

Postero-inferior condylar movement induced by artificial occlusal interference on the balancing side during fictive mastication in rabbits

ObjectiveTooth contact does not occur on the balancing side during mastication. Hence, it is possible that the presence of occlusal interference on the balancing side causes mandibular rotation followed by atypical condylar movement because the jaw-closing muscle activity on the working side is greater than on the balancing side. The aim of the present study was to investigate the relationship between occlusal contact on the balancing side and condylar movement during mastication. MethodsEMG activity of the masseter (MS), lateral pterygoid (LP) and digastric (DG) muscles and jaw movements were recorded. Condylar movements in the sagittal plane were recorded using a high speed charge-coupled device (CCD) camera. Incisal point movements were recorded using a magnet on the mentum and a magnetometric sensor on the nasal bone. A removable biting plate was used to introduce an artificial occlusal interference on the balancing side. ResultsNine of the 10 rabbits showed large postero-inferior condylar movement (Pi-Cm) when a biting plate was applied on the balancing side. Five rabbits showed very small Pi-Cm when a biting plate was applied on the balancing side. In the small Pi-Cm group, MS activity decreased markedly and LP and DG transient activity appeared in the early occlusal phase in the presence of the biting plate. ConclusionInterference on the balancing side always caused Pi-Cm on the ipsilateral side during mastication. However, the degree of Pi-Cm was often decreased by a jaw opening reflex response.

Condylar Movement Assessment is Severe Attrition Patient Undergoing Orthodontic Treatment: Joint Vibrant Analysis Procedure

Orthodontic treatment of the patient with severe teeth attrition was performed with the provisional restorations to recover occlusal vertical dimension. The increase in VDO causes posterior mandibular rotation and the increase in overjet. The overjet correction is one of the main goals of the orthodontic treatment in these patients. The anterior mandibular position was obtained at the end of orthodontic treatment. Condylar positions were assessed immediately after the bite raising procedure and after the completion of treatment. Both CBCTs of the temporomandibular joints and the Joint vibration analysis (JVA) were performed. Coronal views of the CBCTs of TMJs and zoomed vibration views of the JVA of TMJs are essential in assessment of the condylar instability.

Evaluation of three-dimensional mandibular movements after reconstruction with free fibula flap.

SUMMARYSeven patients who underwent mandibular reconstruction with a fibula free flap (one on the midline, six on either right or left side) and were rehabilitated with implant supported prostheses, performed free mandibular border movements (maximal mouth opening and closing, right and left lateral excursions, protrusion) that were recorded by a non-invasive motion analyser. Temporomandibular joint (TMJ) kinematic parameters were compared to those calculated in healthy control subjects using z-scores. Maximum mouth opening was reduced in all patients, with z-scores ranging from -2.742 to -0.106, and performed with a reduced sagittal plane mandibular rotation. Interincisal point forward movement during protrusion was reduced in all but one patient. Lateral mandibular movements (displacement of the interincisal point) and bilateral condylar movements during mouth opening were very variable and sometimes asymmetrical. Mandibular rotation was also variable, with z-scores ranging from -1.265 to 1.388. Together with mandibular range of motion, we investigated biomechanical characteristics of TMJ motion that can provide further information about the joint without submitting the patient to harmful procedures, and that can be followed-up during healing. The investigation indicates those areas that need to be given special attention in preoperative planning, patient information and rehabilitation.

SYMPHYSIS MORPHOLOGY AND DIMENSIONS IN DIFFERENT VERTICAL FACIAL PATTERNS (CBCT SCAN STUDY)

Mandibular symphysis (MS) morphology is a valuable diagnostic and treatment-planning tool in orthodontics. It is utilised as a reference measure for esthetic purposes, specifically in the lower part of the face, as well as to predict the direction of the mandibular growth rotation as the vertical growth direction. The aim of the presenting study is to use cone beam computed tomography (CBCT) to evaluate the MS morphology and dimensions of adults with different vertical facial patterns and had no previous orthodontic treatment. The study consisted of 100 subjects (42 males and 58 females). Mean age of subjects is 27.6 years (average age of men 29.2 years, average age of women 26.4 years). The CBCT images were obtained by Scanora 3D. The evaluation of the different vertical facial patterns was carried out according to Björk and Jarabak. Six lines, four angles and one area were used in the mandibular symphysis study. The study revealed varying correlations between the parameters of the mandibular symphysis and those of the vertical facial patterns. It was found that the convexity of the mandibular symphysis (B-POG-Me) and the distance from POG to the z-axis (POG-Z Axis) are highly correlated to the parameters evaluating the vertical facial patterns. The angle between the Gonion-Nasion line and the mandibular plane (GO2-Angle) and the angle between the palatal and mandibular planes (B-Angle) were highly correlated to the measurements used on the mandibular symphysis.

Craniofacial growth prediction based on mandibular rotation in deep and shallow antegonial notching – A cephalogram study

Craniofacial growth prediction based on mandibular rotation in deep and shallow antegonial notching – A cephalogram study

A Study on the Change of Occlusal Contacts and Lateral Cephalometric Variables after Stabilization Splint Therapy in Temporomandibular Disorders Patients

Purpose: The aim of this study is to assess the relationship between possible occlusal change after stabilization splint therapy and the research diagnostic criteria for temporomandibular disorders (RDC/TMD) Axis I diagnoses and lateral cephalometric variables. Methods: Clinical and radiographic records of 47 TMD patients wearing stablization splint were reviewed. The number of occluding teeth was recorded and lateral cephalogram was taken at pre-treatment and 6-month post-treatment. They were divided into two groups. The control group consists of patients with the unchanged number of occluding teeth throughout 6-month splint therapy (19 females and 4 males), and occlusal-loss group with the number of occluding teeth decreased (19 females and 5 males). The difference of RDC/TMD diagnoses and cephalometric variables were compared between two groups. Results: In the control group, RDC group I, muscle disorders, was 39.1% (9/23), group II, disc displacements, was 17.4% (4/23), group III OA, osteoarthritis/osteoarthrosis, was 73.9% (17/23), and group III pain, arthralgia, was 82.6% (19/23). In the occlusal-loss group, group I was 41.7% (10/24), group II was 41.7% (10/24), group III OA was 70.8% (17/24), and group III pain was 83.3% (20/24). The frequency of RDC groups was not different between two groups, analyzed by binomial logistic regression. Pre-treatment cephalometric variables were not different between two groups. However, articular angle, AB to mandibular plane and ODI decreased and gonial angle increased significantly in the occlusal-loss group, implying clockwise rotation of the mandible, between pre-treatment and 6-month post-treatment, while none of cephalometric variables showed any statistical difference in the control group. Conclusions: Change in the number of occluding teeth was not related to the RDC/TMD diagnoses. Cephalometric values changed only in the occlusal-loss group as a result of mandibular clockwise rotation. None of cephalometric variables before the stabilization splint therapy was statistically different between the control and occlusal loss group.

The effects of altered maxillary growth on patterns of mandibular rotation in a pig model

ObjectivesA thorough understanding of influence of maxillary growth on patterns of mandibular rotation during development is important with regard to the treatment of skeletal discrepancies. In the present study, we examined whether experimentally altered maxillary position has a significant influence on patterns of mandibular rotation in a pig model. DesignMaxillary growth was altered in a sample of n=10 domestic pigs via surgical fixation of the circummaxillary sutures. We compared the experimental group to control and surgical sham samples and assessed the effects of altered maxillary growth on mandibular form using geometric morphometric techniques. We tested for significant differences in mandibular shape between our samples and examined axes of morphological variation. Additionally, we examined whether altered mandibular shape resulting from altered maxillary position was predictably associated with morphological changes to the condylar region. ResultsThere was a statistically significant difference in mandibular shape between the experimental and control/sham groups. As a result of vertical displacement of the snout, mandibles in the experimental sample resulted in greater anterior rotation when compared to the control/sham pigs. Variation in rotation was correlated with morphological changes in the condyle including the shape of the articular surface and condylar orientation indicative of greater anterior mandibular rotation. ConclusionsVertical displacement of the maxilla had a significant effect on mandibular shape by encouraging anterior mandibular rotation. This result has important implications for understanding the effects of altered mandibular posture on condylar remodeling the treatment of skeletal discrepancies such as the correction of hyperdivegent mandibular growth.

Unusual postero-inferior condylar movements that depend on the position of occlusal contact during fictive mastication in rabbits

ObjectiveThe mandible can be modelled as a triangular plate supported at two joints and the point of occlusion. The mandible is stable if the vector of the jaw-closing muscle forces lies within the triangle of support. If this vector lies outside of the triangle of support, one of the three contact points will tend to separate as the mandible rotates around a line connecting the other two points. Here, we examined whether postero-inferior condylar movements (Pi-Cm) due to mandibular rotation may occur during fictive mastication in anaesthetized rabbits. MethodsEMG activities of the masseter (MS) and lateral pterygoid (LP) muscles and movements of the condyle and incisal points were recorded. Condylar movements in the sagittal plane were recorded using a high speed CCD camera. ResultsPi-Cm were observed on the working side during occlusal phase in half of the rabbits (altered-movement group), if the biting point was restricted at the posterior most tooth (M3) on the working side using a metal biting plate. Pi-Cm appeared in the period between the estimated maximum force of the MS and the LP during late occlusal phase. The MS EMG ratio between the working and balancing sides in the altered-movement group was significantly less than that in the unaltered-movement group. ConclusionSince the space lying between the condyle and the articular eminence expanded during the Pi-Cm, it is likely that the posterior band of the articular disc tended to slip anteriorly. The clinical significance of the Pi-Cm is discussed concerning the anterior dislocation of the disc in patients with TMJ disorder.

Non-surgical profile correction in a class II malocclusion

Case report of a 17-year-old male patient, skeletal class II, convex profile, not pleased with his facial appearance and without any intention to undergo surgical treatment. He presents severe protrusion and crowding, lip incompetence and protrusion, 7mm overjet and -3mm overbite. The treatment goals were to improve lip relation and esthetics, establish a functional occlusion, to improve the profile and muscular balance. Four first premolar extractions were performed and anchorage control was accomplished with a transpalatal and lingual arch. Treatment results were very successful achieving functional occlusion, lip competence, mandibular rotation and a decrease in profile convexity without surgical treatment. It is important to know the scopes and limits of orthodontic treatment regarding soft tissues, as well as maintaining anchorage to achieve profile changes with maxillary incisor retraction.

Corrección no quirúrgica del perfil de una maloclusión clase II

Case report of a 17-year-old male patient, skeletal class II, convex profile, not pleased with his facial appearance and without any intention to undergo surgical treatment. He presents severe protrusion and crowding, lip incompetence and protrusion, 7mm overjet and -3mm overbite. The treatment goals were to improve lip relation and esthetics, establish a functional occlusion, to improve the profi le and muscular balance. Four first premolar extractions were performed and anchorage control was accomplished with a transpalatal and lingual arch. Treatment results were very successful achieving functional occlusion, lip competence, mandibular rotation and a decrease in profile convexity without surgical treatment. It is important to know the scopes and limits of orthodontic treatment regarding soft tissues, as well as maintaining anchorage to achieve profile changes with maxillary incisor retraction.

Mandibular rotation revisited: What makes it so important?

Orthodontists have long been aware that mandibular rotation takes place during growth, but most have underestimated its importance. This is so because the distinction between the true rotation and the rotation of the mandibular plane is typically not made. Traditionally, orthodontists have focused on the mandibular plane, which changes little because modeling on the lower mandibular border largely hides the true rotation that occurs. Furthermore, orthodontists must understand that changes in tooth position—over which they have great control—play an important role in determining the true rotational changes that occur. Such an appreciation is of particular importance when evaluating Class II cases, for which true rotation is critically important, in terms of both the development and solution of the problem. Clinically, they must be aware of and able to use the various centers of rotation to prevent deleterious changes from occurring and to orthopedically correct the problems that have developed. Orthodontists must understand that true rotation is the primary determinant of chin position and a major determinant of condylar growth direction, mandibular modeling, and dentoalveolar compensations. They must learn how to take advantage of the mandible's capacity to adapt to rotational changes.

Correction of the occlusal and functional sequelae of mandibular condyle fractures using orthodontic mini-implant molar intrusion

We report on the non-surgical management of an adult female whose bilateral mandibular condylar fractures had resulted in a clockwise (posterior) mandibular rotation, limitation of mandibular movements and increased occlusal loading on the molar teeth. She refused maxillary surgery and was treated with a minimally-invasive approach, involving orthodontic fixed appliances and mini-implant intrusion of the maxillary molar teeth. This provided both occlusal and functional improvements, including a significant increase in the inter-incisal distance, which were stable after one year of retention.

Protracción ortopédica maxilar en retrognatismo de fisurados y no fisurados y comparación con norma ecuatoriana. 2013

The effectiveness of maxilla protraction of the facial mask prior to palatal expansion was evaluated in bothfissured and non-fissured palate patients , Class III skeletal relationship ,in proportion to the EcuadorianUniverse Standard 81 H. C. FUNARMAF,sampling through cephalometric analysis: 21 H. C. fissured patients(26 % ), (15m, 6f ), average age:12 11mths, and 7 H. C. non-fissured (9 % ), (3m,4f) average age: 11 consists of 35% of the universe, temporary teeth, mixed and young permanent teeth . 19 Angular measuresand 12 linear measures were compared pre post-treatment; postreatment average Ecuadorian standard(9m: 21f), Class I dental and skeletal relationship, average age 16 2mths. Average treatment time 16mthsfissured; 20ms non-fissured; Statistical test: t Test pairs. Treatment develops significant trend of growthtime (p < 0.05 ) with severe mandibular rotation, maxillary increase in height and lower facial height exceeding standard average, severe dolicofacial pattern , more accentuated in fissured patients , maxillary advance and normal intermaxillary relationship ; improvement in protrusion and inclination upper and lowerincisors, overjet and overbite without reaching fissured group; little significant difference with the standardgroup non-fissured, with the exception of retroclinacion of lower incisors. Lower lip exceeds standard significantly in fissured group, affecting facial profile.

Phenotypic diversity in white adults with moderate to severe Class II malocclusion

Class II malocclusion affects about 15% of the population in the United States and is characterized by a convex profile and occlusal disharmonies. The specific etiologic mechanisms resulting in the range of Class II dentoskeletal combinations observed are not yet understood. Most studies describing Class II phenotypic diversity have used moderate sample sizes or focused on younger patients who later in life might outgrow their Class II discrepancies; such a focus might also preclude the visualization of adult Class II features. The majority have used simple correlation methods resulting in phenotypes that might not be generalizable to different samples and thus might not be suitable for studies of malocclusion etiology. The purpose of this study was to address these knowledge gaps by capturing the maximum phenotypic variations in a large sample of white Class II subjects selected with strict eligibility criteria and rigorously standardized multivariate reduction analyses. Sixty-three lateral cephalometric variables were measured from the pretreatment records of 309 white Class II adults (82 male, 227 female; ages, 16-60 years). Principal component analysis and cluster analysis were used to generate comprehensive phenotypes to identify the most homogeneous groups of subjects, reducing heterogeneity and improving the power of future malocclusion etiology studies. Principal component analysis resulted in 7 principal components that accounted for 81% of the variation. The first 3 components represented variation on mandibular rotation, maxillary incisor angulation, and mandibular length. The cluster analysis identified 5 distinct Class II phenotypes. A comprehensive spectrum of Class II phenotypic definitions was obtained that can be generalized to other samples to advance our efforts for identifying the etiologic factors underlying Class II malocclusion.