Three-Dimensional Mandibular Condyle Remodeling Post-Orthognathic Surgery: A Systematic Review.

Background and Objectives: The most popular surgical procedures among orthognathic surgeries for Class II and III patients are Le Fort 1 osteotomy for the maxilla and bilateral sagittal split ramus osteotomy (BSSRO) for the mandible. Keeping the condyle in its proper place during fixation is one of the difficulties of orthognathic surgery. One of the worst post-orthognathic surgery consequences in the temporomandibular joint (TMJ) area may be condylar resorption. Condylar remodeling refers to a group of processes that occur in reaction to forces and stress placed on the temporomandibular joint in order to preserve morphological, functional, and occlusal balance. A systematic review of the literature was performed with the aim of identifying the mandibular condylar component of TMJ changes after orthognathic surgery in class II and III patients. Materials and Methods: An electronic search was carried out using the PubMed, Cochrane Library, and Google Scholar, databases. The inclusion criteria included trials in non-growing patients upon whom orthognathic surgery was performed due to Angle II or Angle III classes malocclusion; in addition, a CT or cone beam computed tomography (CBCT) scan was performed before and after surgery to track the mandibular condylar component of TMJ changes. The quality of the studies was evaluated by two independent authors. The risk of bias was assessed by using the Downs and Black checklist. Results: The electronic and manual literature search yielded 12 studies that fulfilled all necessary inclusion criteria. Observed studies were evaluated as good (3), fair (8), and poor (1) quality. Two studies evaluated class II patients, six studies observed class III patients, and four studies were comparative. Most of the studies evaluated condyle angle and space changes, and the condylar surface and volume changes were also observed. However, the methodology of evaluation in the publications differs. Conclusions: Reduction of bone density, especially in class II patients, and morphological condyle reshaping, with the apposition of the bone, is the main adaptive mechanism after orthognathic surgery. However, all of the studies we examined were conducted using different methods of evaluation, measurement, and reference points.

The preliminary study of the effects of individual musculoskeletally stable position in the treatment of temporomandibular disorders.

BACKGROUND: Temporomandibular Disorders (TMD) is the dysfunction of group of muscles and bones in the joint area, the main symptoms of TMD are the pain of the chewing muscles and (or) the temporomandibular joints, mandibular movement disorders and joint noise. This study was designed to explore the therapeutic effects following Individual Musculoskeletally Stable (IMS) position stabilization splint therapy for TMD patients using Fricton index, cone beam computed tomography (CBCT) and surface-Electromyogram (sEMG). METHODS: In this study, we enrolled 31 TMD patients (ranging from 18 to 26 years old, including 7 males and 24 females), first Fricton index was used to evaluate the clinical curative effect of TMD with the treatment of IMS stabilization splint; then CBCT was used to observe the TMJ condylar position changes of TMD before and after the treatment of IMS stabilization splint; finally sEMG was used to observe the changes of electromyography of anterior temporalis (AT) and masseter muscles (MM) of TMD before and after the treatment of IMS stabilization splint. RESULTS: The course of treatment was 6-8 months, with an average of 7.6 months. After the IMS stabilization splint treatment, TMD symptoms relieved, especially in pain, mandibular movement disorder, but still slightly inferior in the treatment of joint noise. And there was a statistically significant difference in the anterior and inner joint space, the condyle had the tendency of moving forward and outward. AT presented reduction significantly of EMG value at rest position after treatment. CONCLUSIONS: IMS stabilization splint is a therapeutic reversible treatment for TMD, especially for pain and mandibular movement disorder; it produces effects of forward and outward condylar movement and elimination of the masticatory muscles antagonism.

A finite element analysis on the indication for extracting partially impacted mandibular third molars considering mandibular trauma.

BACKGROUND: Patients presenting with partially impacted lower third molars (M3) have a higher likelihood of experiencing angle fractures while simultaneously decreasing the risk of condylar fractures. However, the specific biomechanical mechanism responsible for this occurrence remains unclear. Moreover, there is an ongoing debate regarding whether the removal of M3s might actually increase the risk of condylar fractures. This study aimed to evaluate how the presence of M3s influences mandibular fractures resulting from blows to the symphysis and lateral mandibular body, and to determine the indication for extracting M3s in such cases. METHODS: Models of the mandible with a partially M3-impacted model (M3I), M3-extracted model (M3E), and M3-absent model (M3A) were generated using a computer. A traumatic blown force of 2000 N was applied to the symphysis and the right body of the mandible. Von Mises and principal stresses were analyzed, and failure indexes were determined. Two cases of mandibular linear fractures were chosen for model verification and interpretation. RESULTS: When force was applied to the symphysis, the condylar region exhibited the highest stress levels, while stress in the mandibular angle region was much less regardless of the M3 state. On applying the force to the right mandibular body, stress in the condylar region decreased while stress in the mandibular body increased, especially in the blown regions. Impacted tooth or cavity formation post-M3 extraction led to uneven stress distribution on the blown side of the mandible, increasing the risk of mandibular angle fractures. In cases where M3 was absent or the extraction socket had healed, stress from lateral traumatic blown force was evenly distributed along both the inner and outer oblique lines of the mandible, thereby reducing the risk of mandibular fractures. CONCLUSIONS: The reduced risk of condylar fractures in patients with partially impacted lower M3s and mandibular angle fractures is mainly due to lateral blows on the mandible, which generate less stress in the condylar region than blows on the mandibular symphysis, rather than being caused by the M3 itself. Extraction of the lower M3 can decrease the risk of mandibular fractures, with a minor influence on condylar fractures.

Instrumental Occlusal Analysis in Migraine Patients: A Quantitative Cross Sectional Study.

OBJECTIVES: This study aimed to investigate possible differences of functional occlusal variables between a group of migraine patients (MG) and a control group (CG). MATERIALS AND METHODS: Each group included 50 individuals. Instrumental functional analysis and digital occlusal analysis were performed. Variables examined were condylar displacement from a reference position to maximum intercuspation; angular difference between the steepness of the articular eminence and the contra-lateral canine guidance; and angular difference between the steepness of the articular eminence and the ipsilateral central incisor guidance and occlusal plane inclination. Self-reported grinding and occlusal index were also investigated. RESULTS: There were statistically significant differences in the extent of retral condylar displacement assessed both clinically [MG: 0.49 mm (SD 0.67 mm), CG: 0.29 mm (SD 0.27 mm), p = 0.012] and digital-mechanically [MG: 1.53 mm (SD 0.95 mm), CG: 0.9 mm (SD 0.66 mm), p = 0.001], the angular difference between the steepness of the articular eminence and the contra-lateral canine guidance [MG: 13.11° (SD 8.33°), CG: 9.47° (SD 7.08°), p = 0.021 and MG: 12.94° (SD 8.71°), CG: 9.44° (SD 8.70°), p = 0.017], and the occlusal plane inclination [MG: 11.16° (SD 4.66°), CG: 9.09° (SD 4.37°), p = 0.024]. Self-reported grinding (MG: 39/50, CG: 12/50, p < 0.001) and occlusal index [MG: 1.92 (SD 0.46), CG: 0.21 (SD 0.66), p < 0.001] were also significantly higher in migraineurs. CONCLUSIONS: Articular and occlusal structures could play a role in migraine and thus should be considered in an interdisciplinary approach.

Biomechanical evaluation of various rigid internal fixation modalities for condylar-base-associated multiple mandibular fractures: A finite element analysis.

Condylar-base-associated multiple mandibular fractures are more prevalent than single ones. Direct trauma to mandibular symphysis, body or angle are prone to induce indirect condylar fracture. However, little is known about the effects of various rigid internal fixation modalities in condylar base for relevant multiple mandibular fractures, especially when we are confused in the selection of operative approach. Within the finite element analysis, straight-titanium-plate implanting positions in condylar base contained posterolateral zone (I), anterolateral zone (II), and intermediate zone (III). Von Mises stress (SS) in devices and bone and mandibular displacement (DT) were solved, while maximum values (SSmax and DTmax) were documented. For rigid internal fixation in condylar-base-and-symphysis fractures, I + II modality exhibited least SSmax in screws and cortical bone and least DTmax, I + III modality exhibited least SSmax in plates. For rigid internal fixation in condylar-base-and-contralateral-body fractures, I + III modality exhibited least SSmax in screws and cortical bone, I + II modality exhibited least SSmax in plates and least DTmax. For rigid internal fixation in condylar-base-and-contralateral-angle fractures, I + III modality exhibited least DTmax. The findings suggest that either I + II or I + III modality is a valid guaranty for rigid internal fixation of condylar base fractures concomitant with symphysis, contralateral body or angle fractures.

Idiopathic condylar resorption in adolescents: A scoping review.

OBJECTIVE: Idiopathic condylar resorption (ICR), also known as progressive condylar resorption, is poorly understood, particularly in adolescent patients. Therefore, this scoping review aims to summarize the available literature on the prevalence, aetiology, pathogenesis, diagnostic process, treatment and/or any outcome regarding ICR in adolescent individuals. METHODS: This scoping review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and its extension for scoping reviews (PRISMA-ScR), as well as Joanna Briggs Institute studies. The search strategy was defined adopting a core search structure for each source, and the search was performed on MEDLINE, EMBASE, Cochrane Library, Web of Science, Scopus and Google Scholar. After duplicate removal, two independent reviewers screened abstracts, followed by complete articles, to achieve the definition of included studies. Data collection was performed, and the extracted data were organized in tabular form, along with a narrative summary of main findings that aligns with the objective of this review. RESULTS: Six observational studies were included in this review. Three studies focused on signs and symptoms, one on prevalence and signs and symptoms, one on treatment and one on disease pathogenesis. CONCLUSION: This scoping review revealed inadequate published research regarding prevalence, aetiology, early diagnosis, pathogenesis and treatment of ICR in adolescents.

Modificación de la actividad metabólica por medio de un dispositivo intraoral en pacientes con hiperplasia condilar confirmada por SPECT / Metabolic activity modification by means of an intraoral device in patients with condylar hyperplasia confirmed by SPECT

Objetivo: Evaluar los efectos de la aplicación de un dispositivo intraoral de uso permanente en el comportamien- to de los cóndilos con hiperplasia condilar (HC) confirmada por tomografía computarizada de emisión por fotón único (SPECT), estableciendo una comparación con un grupo de pacientes con HC que no utilizó el dispositivo. Materiales y métodos: 30 pacientes con una edad promedio de 21,7 años (+/-5,56) con HC confirmada con SPECT fueron asignados al azar a dos grupos: a los del grupo I (n=18) se les colocó un dispositivo intraoral de uso perma- nente para modificar la posición de la mandíbula, mientras que a los del grupo II (n=12) no se les colocó ningún dispo- sitivo. Se realizaron evaluaciones de dolor, del desvío de la línea media, de la apertura máxima y del disconfort al inicio del estudio y a los 2, 4, 6, 10, 12 y 14 meses. A los 19 meses promedio, la actividad osteoblástica (AO) fue reevaluada me- diante SPECT. Resultados: En el grupo I, la AO en los cortes coro- nales y transversales cesó o disminuyó (p<0,001) respecto a la condición inicial, mientras que en el grupo II la AO au- mentó (p<0,001). Los datos fueron analizados utilizando el test de Wilcoxon de rangos signados. Al ajustar un modelo de ANCOVA robusto utilizando el valor inicial como covariable también se observa que el efecto del grupo fue estadística- mente significativo en ambos cortes (p<0,001). Conclusiones: La aplicación de un dispositivo intrao- ral de uso permanente mejora la evolución de la hiperplasia condilar, lo que lo puede convertir en un tratamiento de uti- lidad para el tiempo que se aguarda para realizar una condi- lectomía alta de cuello de cóndilo, o incluso para evitar este procedimiento (AU)

Objective: To evaluate the effects of the application of an intraoral device for permanent use on the behavior of con- dyles with condylar hyperplasia (CH) confirmed by single photon emission computed tomography (SPECT), establish- ing a comparison with a group of patients with CH that did not use the device. Materials and methods: Thirty patients with an aver- age age of 21.7 years (+/-5.56) with CH confirmed by SPECT were randomly divided into two groups: the ones in group I (n=18) received an intraoral device for permanent use to align the mandible, while those in group II (n=12) did not get any device. Pain, midline shift, maximum opening, and discomfort were evaluated at the beginning of the study and at 2, 4, 6, 10, 12, and 14 months. At an average of 19 months, osteoblastic activity (AO) was reassessed by SPECT. Results: In group I, the AO in the coronal and trans- verse sections ceased or decreased (p<0.001) in comparison to the initial condition, while in group II the AO increased (p<0.001). The data was analyzed by the Wilcoxon signed rank test. Adjusting a robust ANCOVA model using the ini-tial value as a covariate made it possible to observe that the effect of the group was statistically significant in both cuts (p<0.001). Conclusions: The application of an intraoral device for permanent use improves the evolution of condylar hyperpla- sia, which can make it a useful treatment until a high condylectomy of the neck of the condyle is performed, or even to avoid this procedure (AU)

Parathyroid hormone promotes cartilage healing after free reduction of mandibular condylar fractures by upregulating Sox9.

After high fractures of the mandibular condyle, the insufficient blood supply to the condyle often leads to poor bone and cartilage repair ability and poor clinical outcome. Parathyroid hormone (PTH) can promote the bone formation and mineralization of mandibular fracture, but its effects on cartilage healing after the free reduction and internal fixation of high fractures of the mandibular condyle are unknown. In this study, a rabbit model of free reduction and internal fixation of high fractures of the mandibular condyle was established, and the effects and mechanisms of PTH on condylar cartilage healing were explored. Forty-eight specific-pathogen-free (SPF) grade rabbits were randomly divided into two groups. In the experimental group, PTH was injected subcutaneously at 20 µg/kg (PTH (1-34)) every other day, and in the control group, PTH was replaced with 1 ml saline. The healing cartilages were assessed at postoperative days 7, 14, 21, and 28. Observation of gross specimens, hematoxylin eosin staining and Safranin O/fast green staining found that every-other-day subcutaneous injection of PTH at 20 µg/kg promoted healing of condylar cartilage and subchondral osteogenesis in the fracture site. Immunohistochemistry and polymerase chain reaction showed that PTH significantly upregulated the chondrogenic genes Sox9 and Col2a1 in the cartilage fracture site within 7-21 postoperative days in the experimental group than those in the control group, while it downregulated the cartilage inflammation gene matrix metalloproteinase-13 and chondrocyte terminal differentiation gene ColX. In summary, exogenous PTH can stimulate the formation of cartilage matrix by triggering Sox9 expression at the early stage of cartilage healing, and it provides a potential therapeutic protocol for high fractures of the mandibular condyle.

Predisposing conditions for condylar sag after intraoral vertical ramus osteotomy.

Intraoral vertical ramus osteotomy (IVRO) is used to treat mandibular prognathism and temporomandibular disorders. However, the improvement of temporomandibular disorders after IVRO is considered to be due to the anterior and downward movement of the mandibular condyle, which may lead to condylar sag, and in the worst case, condylar luxation. In this retrospective cohort study, we examined factors potentially associated with condylar sag. Univariate analysis indicated that condylar sag was significantly associated with the following factors: magnitude of setback (P = 0.001), less than 3 mm setback (P < 0.001), presence of temporomandibular joint (TMJ) symptoms (P = 0.002), Wilkes classification (P = 0.039), occlusal cant correction ≥ 2 mm (P = 0.018), and mandibular condyle deformation (P < 0.001). Setback magnitude (P = 0.032) and TMJ symptoms (P = 0.007) remained significant in the multivariate analysis. In the receiver operating characteristic curve, the setback magnitude cut-off value for condylar sag after IVRO was 3.25 mm. Thus, the incidence of condylar sag after IVRO is increased with a smaller setback magnitude (≤ 3.25 mm) and the presence of TMJ symptoms. These factors should be evaluated by surgeons during treatment planning for IVRO to estimate condylar sag, and it may be possible to predict the risk of condylar luxation.

Effectiveness of low-intensity pulsed ultrasound on osteoarthritis of the temporomandibular joint: A review.

Loading is indispensable for the growth, development, and maintenance of joint tissues, including mandibular condylar cartilage, but excessive loading or reduced host adaptive capacity can considerably damage the temporomandibular joint (TMJ), leading to temporomandibular joint osteoarthritis (TMJ-OA). TMJ-OA, associated with other pathological conditions and aging processes, is a highly degenerative disease affecting the articular cartilage. Many treatment modalities for TMJ-OA have been developed. Traditional clinical treatment includes mainly nonsurgical options, such as occlusal splints. However, non-invasive therapy does not achieve joint tissue repair and regeneration. Growing evidence suggests that low-intensity pulsed ultrasound (LIPUS) accelerates bone fracture healing and regeneration, as well as having extraordinary effects in terms of soft tissue repair and regeneration. The latter have received much attention, and various studies have been performed to evaluate the potential role of LIPUS in tissue regeneration including that applied to articular cartilage. The present article provides an overview of the status of LIPUS stimulation used to prevent the onset and progression of TMJ-OA and enhance the tissue regeneration of mandibular condylar cartilage. The etiology and management of TMJ-OA are explained briefly, animal models of TMJ-OA are described, and the effectiveness of LIPUS on cell metabolism and tissue regeneration in the TMJ is discussed.

Reabsorción Condilar como Complicación Postoperatoria en Pacientes Sometidos a Cirugía Ortognática. Revisión Narrativa / Condylar Resorption as a Postoperative Complication in Patients Undergoing Orthognathic Surgery. Narrative Review

RESUMEN: La reabsorción condilar como complicación postoperatoria en cirugía ortognática es una causa frecuente de recidiva de anomalías dentomaxilares, existiendo diversos factores que se relacionan con su aparición. El objetivo de este estudio fue describir mediante una revisión narrativa la reabsorción condilar como complicación postoperatoria en cirugía ortognática. Se realizó una búsqueda electrónica de la literatura en las bases de datos electrónicas PubMed, EBSCO, TripDatabase y Epistemonikos sin límite de años, en idioma inglés y español, incluyendo revisiones sistemáticas, ensayos clínicos y estudios observacionales. Se excluyeron reportes de casos, estudios en animales y aquellos que no relacionaran la complicación con cirugía ortognática. Se evaluaron los estudios según grado de recomendación y calidad de reporte. Veintiún artículos fueron seleccionados según los criterios de selección establecidos en esta revisión. La literatura reportada sugiere que la reabsorción condilar es una patología de frecuencia relativa en pacientes postoperados de cirugía ortognática (1,4-32 % de los casos) y que está asociada a factores de riesgo preoperatorios tales como género, edad, tipo de anomalía dentomaxilar y técnica quirúrgica utilizada. La reabsorción condilar es una complicación postoperatoria a cirugía ortognática que debemos considerar en la planificación del tratamiento e identificar pacientes con factores de riesgo. Luego de la intervención quirúrgica es de vital importancia realizar un seguimiento estricto a este tipo de pacientes e identificar de forma temprana cambios clínicos y radiográficos. Finalmente, es importante seguir investigando sobre esta materia para establecer criterios de prevención y diagnóstico, con mayor claridad.

ABSTRACT: Condylar resorption as a complication following orthognathic surgery is considered to cause dento-facial anomalies, relating to different pre and intra-operative factors. The aim of the research was to describe condylar resorption as a postoperative complication after orthognathic surgery. A review of the literature was made in four databases: PubMed, EBSCO, Trip database and Epistemonikos. The search was carried out without year limiting, articles in English and Spanish, including systematic reviews, observational studies and clinical trials. Exclusion criteria were applied for report cases, animal studies and articles that do not relate condylar resorption with orthognathic surgery. Quality of evidence and strength of the recommendations were assessed for the chosen studies. For this study 21 articles were selected following the inclusion criteria. The literature found reported that condylar resorption is a relatively frequent complication following orthognathic surgery (1.4-32 % of frequency) and that it can be associated with several factors such as genre, age, dento-maxillary anomaly and surgical technique. Condylar resorption is a complication that we must consider in the planning of orthognathic surgery, in order to identify risk factors and patients who are more likely to present this post-surgical complication. Following surgery, strict follow-up is a key factor to determine early clinical and radiographic changes. Finally, further research is needed to establish stronger prevention and diagnostic criteria.

Association of Temporomandibular Joint Osseous Changes with Anxiety, Depression, and Limitation of Mandibular Function in Elderly Vietnamese.

OBJECTIVES: This study aimed (1) to determine the prevalence of anxiety, depression, and TMJ osseous changes in elderly Vietnamese according to sex and residence, and (2) to investigate the association of temporomandibular joint (TMJ) osseous changes with anxiety, depression, and limitation of mandibular function. METHODS: Elderly people living in Danang, Vietnam were recruited. Participants were screened for anxiety and depression using the self-reported 7-item Generalized Anxiety Disorder Scale (GAD-7) and 9-item Patient Health Questionnaire (PHQ-9), respectively. Participants then self-rated the limitation of their mandibular function using the 20-item Jaw Functional Limitation Scale (JFLS-20) questionnaire. TMJ osseous changes (erosion, flattening, osteophytes, and sclerosis) were evaluated using digital orthopantomography. RESULTS: Of 179 participants aged 65 to 74 years, 17.9% and 35.8% had anxiety and depression symptoms, respectively. Compared with urban residents, rural residents had higher prevalence of anxiety (23.3% vs 12.4%, p = 0.009) and depression (46.62% vs 24.7%, p = 0.019). The prevalence of TMJ osseous changes was 58.1%. The most common TMJ osseous change was flattening (41.3%), followed by erosion (34.6%), sclerosis (16.2%), and osteophytes (7.8%). Participants with or without TMJ osseous changes were comparable in terms of GAD-7 score, PHQ-9 score, and JFLS-20 score and sub-scores. CONCLUSIONS: Anxiety and depression and TMJ osseous changes were prevalent in elderly Vietnamese. Rural residents had higher prevalence of anxiety and depression than urban residents. TMJ osseous changes were not associated with anxiety, depression, or limitation of mandibular function.

Protective Effects of Low-Intensity Pulsed Ultrasound on Mandibular Condylar Cartilage Exposed to Mechanical Overloading.

The aim of this study was to assess the effect of low-intensity pulsed ultrasound (LIPUS) application on rat temporomandibular joints (TMJs) with early-stage of osteoarthritis-like conditions induced by mechanical overloading. Fifteen-week-old male Wistar rats were divided into two experimental groups and a control group (n = 10 each). Both TMJs of all rats in one experimental group were subjected to mechanical overloading for 5 d, and those in the other experimental group were exposed to LIPUS for 20 min/d after overloading. Condyles were assessed using micro-computed tomography, histology and histomorphometry. LIPUS treatment attenuated cartilage degeneration, decreased the number of osteoclastic cells and restored the expression of aggrecan after an initial decrease induced by mechanical overloading. These results indicate that LIPUS may have a protective effect on the early progression of TMJ osteoarthritis.

Investigating possible correlation between condylar asymmetry and clinical dysfunction indices in patients with temporomandibular dysfunction using Cone-beam computed tomographic.

PURPOSE: Temporomandibular disorder (TMD) is a common problem in modern societies. Causes of TMD, as a consequence of condylar asymmetry index (CAI), are still a subject of controversy. The aim of the present study was to determine the possible correlations between the degree of condylar asymmetry and clinical dysfunction indices. MATERIALS AND METHODS: In this cross-sectional study, we used the Habets method to measure the CAI in 42 TMD patients. The participants' age and sex were matched in the control group. Patients were divided into mild, moderate and severe dysfunction groups based on Helkimo's clinical Di. The data were analyzed using Mann-Whitney U and Kruskal-Wallis tests. Also, the study attempted to assess the possibility of correlation between age and CAI. RESULTS: The CAI values of TMD patients were significantly higher than those of the control group (P = 0.001). However, CAI was not significantly different among TMD patients with different dysfunction index. There was no significant correlation between CAI and age (Spearman r = 0.655, P = 0.23). CONCLUSION: Based on the findings of the present study, patients with condylar asymmetry index are more susceptible to TMD. However, degree of the condylar asymmetry is not a criterion for TMD signs and symptoms.

Condylar head remodeling compensating for condylar head displacement by orthognathic surgery.

The purpose of this study was to evaluate the association between kind of condylar displacement due to orthognathic surgery and the subsequent adaptive condylar head remodeling. The sample in this retrospective cohort study consisted of 30 patients (12 female and 18 male; mean age 22.7 y) with skeletal Class III malocclusion who underwent bilateral sagittal split ramus osteotomy (SSRO). Three-dimensional superimpositions of cone-beam computed tomography (CBCT) scan derived images from immediately after and 6 months after surgery were to reveal the type of remodeling, while images from before and immediately after surgery were to identify the type of condylar displacement. Laterally displaced condyles showed bone resorption on the lateral surfaces and deposition on the medial surfaces, whereas the contrary was found in medially displaced condyles. Anteriorly displaced condyles showed resorption on the anterior surfaces and deposition on the posterior surfaces, whereas the contrary was found in posteriorly displaced condyles. Superior surfaces of the condyles showed bone resorption regardless of displacement direction. The results indicate that condylar remodeling patterns (resorption/deposition) are determined by the direction of condylar displacement during surgery. However, condylar displacement by surgery is not completely compensated by condylar head remodeling, especially in case of downward displacement.

Osseous changes of the mandibular condyle affect backward-rotation of the mandibular ramus in Angle Class II orthodontic patients with idiopathic condylar resorption of the temporomandibular joint.

Objective: To evaluate whether osseous changes of the temporomandibular joint (TMJ) condyle affect backward rotation of the mandibular ramus in Angle Class II orthodontic patients with idiopathic condylar resorption (ICR). Methods: Twenty Japanese women with Class II malocclusion with ICR (ICR group) and 24 women with Class II malocclusion without ICR (non-ICR group) were examined. Pre-treatment panoramic radiographs were used to measure condylar ratios. Pre-treatment lateral cephalograms were used to evaluate maxillofacial morphology. Results: The ICR group had a significantly smaller condylar ratio, greater backward rotation of the ramus, less labially inclined upper incisors, and a steeper occlusal plane. The increased backward rotation of the ramus in the ICR group was significantly associated with a smaller condylar ratio. Conclusion: Angle Class II patients with ICR had shorter condylar height attributable to osseous changes of the TMJ condyle, and the shorter condylar height may affect subsequent backward rotation of the ramus.

Alterations of mandibular movement patterns after total joint replacement: a case series of long-term outcomes in patients with total alloplastic temporomandibular joint reconstructions.

According to recognized guidelines, a total alloplastic replacement may be indicated to resolve temporomandibular pain and functional limitations in cases where conservative and less aggressive surgical management strategies have failed. It is broadly believed that, as a result of the surgical procedure, the function of the lateral pterygoid muscle is lost and so are the laterotrusive and protrusive jaw movements. Furthermore, the joint prosthesis design may not be conducive to lateral and protrusive movements. Using a dynamic stereometry technique, it was possible to perform a quantitative analysis of kinematics in TJR patients. The cases of four patients who showed preserved lateral and/or protrusive motion are presented here. During mouth opening, prosthetic condyle translation ranged from 3.18mm to 10.09mm and it was also possible to observe this clinically. It has been suggested that changes in prosthesis design may have improved postoperative jaw kinematics. Considering the large diversity in treatment outcomes, it is recommended that the individual prognosis should always be discussed with the patient prior to surgery.

Inclination of the condylar long axis is not related to temporomandibular disc displacement.

AIM: The aim of the present study was to correlate the angle formed by inclination of the condylar long axis and median sagittal plane to the presence of internal disc derangement, as well as changes in eccentric mandibular positions. METHODS: The sample consisted of magnetic resonance images of 35 temporomandibular joint (TMJ) acquired with a 1.5T magnetic resonance imaging system with surface coils of 8.5 cm in diameter. Parasagittal images were used according to the following parameters: TMJ disc position with mouth closed, TMJ disc position with mouth open, TMJ disc function, and degrees of rotation and translation of the condyle. Next, we determined the angles between the condyle long axis and median sagittal plane by using axial images. RESULTS: The results showed correlations between TMJ disc position and disc function (P = 0.009), as well as between disc position and degree of condylar rotation (P = 0.008). The main purpose of the present study was to assess the angle of the condylar long axis, with no statistical correlation being found between this variable and disc position (P = 0.787), disc function (P = 0.091), condylar translation (P = 0.808), and condylar rotation (P = 0.115). CONCLUSION: There was no relationship between inclination of the condyle long axis and parameters of internal derangements.

Micro-CT observation of in vivo temporal change in mandibular condyle morphology in BMAL1 knockout mice.

Brain and muscle Arnt-like protein-1 (BMAL1) knockout mice exhibit accelerated aging, abnormal glucose metabolism, and impaired adipocyte differentiation, among other phenotypes, which are effects associated with the BMAL1 gene. No study has investigated temporal changes in the deformation of the mandibular condyle and the presence of calcification in areas surrounding the mandibular condyle. In a study of 12 C57/BL strain mice under inhalation anesthesia, we collected images of the mandibular condyle at 6 weeks after birth and then every 5 weeks from 10 to 25 weeks after birth. At 25 weeks, deformation of the mandibular condyle was seen in 8 of 12 joints in BMAL1 knockout mice and in 2 of 12 joints in wild-type mice. At 20 and 25 weeks, deformation in areas surrounding the mandibular condyle, which are known to undergo calcification, was seen in 2 of 12 joints in BMAL1 knockout mice and in 0 of 12 joints in wild-type mice. BMAL1 knockout mice exhibited premature aging of the mandibular condyle, which suggests that circadian rhythms affect mandibular condyle morphology.

Three-Dimensional Analysis of Perioperative Condylar Displacement After Mandibular Setback Surgery With Intended Manual Condylar Positioning.

PURPOSE: The purpose of this study is to investigate the effect of orthognathic surgery with intended manual condylar positioning on condyle by examining a change in its position. METHOD: About 18 patients with mandibular prognathism who underwent orthognathic surgery with intentional manual condyle positioning were included. Condyle displacement was analyzed through 3D cone-beam computed tomography before and after operation. The patients were categorized into 2 experimental groups: group A (1-jaw) and group B (2-jaw). The experimental groups were examined before surgery (T0), 3 days (T1), and 6 months (T2) after surgery. Condylar displacement direction was investigated in terms of bodily shift and rotational movement. RESULTS: Downward bodily shift of condyle after surgery was significantly apparent from all of the patients. Condylar bodily shift in other directions was statistically insignificant. Gross bodily shift of condyle right after surgery was anterolateral-inferior direction. In perspective of rotational movement, condyle rotated in infero-medial direction right after operation, but no significant change was presented afterwards. In addition, no significant difference in the amounts of condylar shift and pattern existed between groups A and B. CONCLUSION: Intended manual condylar positioning may minimize postoperative displacement of condyle while accomplishing skeletal stability.