Facial Skeletal Structure Research Articles

The Role of Maxillofacial Structure and Malocclusion on Condylar Displacement in Maximum Intercuspation and Centric Relation in Patients Seeking Orthodontic Treatment-A Scoping Review.

Available knowledge about malocclusion and cephalometric variables and their connection with an increased risk of condylar displacement (CD) is scarce. This article aims to present current information on the relationship between centric relation-maximum intercuspal position discrepancies and maxillofacial morphology and malocclusion in patients seeking orthodontic treatment as well as to identify those who require expanded diagnostic evaluation for this disorder. This review analyzed the PubMed, Cochrane Library, Web of Science, and Scopus electronic databases up to February 2022. Keywords and additional manual searches were performed. Literature selection was based the PRISMA-ScR checklist. The JBI Critical Appraisal Tool assessed the methodological quality of included studies. The databases search provided 2321 studies. A total of 10 studies were included in this review after eligibility criteria and JBI assessment. This review was separated into five parts that evaluated CD correlations depending on the following: maxillofacial structure in different vertical and sagittal skeletal patterns, vertical, horizontal, and transverse malocclusions. A hyperdivergent facial skeletal structure is a risk factor for increased CD, particularly in the vertical dimension. The condylar processes are usually displaced in a posteroinferior direction. Further studies are warranted to elucidate the relationship among remaining skeletal and dental malocclusions and the occurrence of CD.

Differences in craniofacial morphology between platybasic and nonplatybasic patients with velopharyngeal dysfunction and control subjects

This study aimed to identify the characteristics of cranial-base morphology in platybasic and nonplatybasic patients with palatal anomalies and velopharyngeal dysfunction (VPD) compared with control subjects to investigate structural factors related to craniofacial morphology that affect the nasopharyngeal space and may influence velopharyngeal function, and to develop precise treatments for specific patients with VPD. Three hundred eighty-six patients with VPD and various palatal anomalies were studied retrospectively. The control group included 126 healthy patients with normal speech. Lateral cephalometric images assessed craniofacial morphology. Nonplatybasic patients and control subjects had larger SNA, S-Ba-Ptm, and N-Ba-PP angles (in the craniomaxillary complex), and platybasic patients had larger nasopharyngeal ANS-Ptm-Ve and Ba-S-Ptm angles and longer Ve-T and Ve-Ba distances than the nonplatybasic patients. All study patients had larger ANB, Gn-Go-Ar, and PP-MP angles (in the craniomandibular complex). Nonplatybasic patients had smaller Ba-SN angles than platybasic patients and controls because of more acute N-S-Ptm angle. Among the nonplatybasic patients, Ve-T length tended to be shorter (with no significant difference between groups) and located more inferiorly (because of the smallest ANS-Ptm-Ve angle) in relation to the maxilla. Thus, the nasopharynx was narrower horizontally but longer vertically than in patients with platybasia. Cranial-base flexure influences the shape of the skull base and facial-skeletal structure and may alter the pharyngeal space between them. This finding should help improve preoperative planning regarding the effect of the pharyngeal flap height relative to the nasopharynx and oropharynx ratio that affects surgical outcomes, such as resonance and residual VPD. In patients with Class III malocclusion and maxillary constriction, careful planning of presurgical orthodontic treatment is needed in maxillary advancement procedures. Orthodontic and surgical collaboration can help prevent postoperative VPD, especially in platybasic patients.

Craniofacial characteristics in Van der Woude syndrome.

To describe the particular craniofacial characteristics of Van der Woude syndrome(VWS) patients compared to patients with a non-syndromic cleft (CG1) and to a malocclusive healthy population (CG2). Retrospective case-control study. A sample of 110matched-patients was recruited (VWS (n=7), CG1 (n=49), CG2 (n=49)). Subsequently, 37radiometric variables were analysed and the dental-skeletal ages were determined. The intra/inter-observer method errors were quantified. Descriptive statistics were computed, and different inferential analysis tests were used depending on the normality of the data (Chi-square test, Fisher's exact test, paired Student's T-test, Mann-Whitney U test) (p-value < 0.05). Pairwise comparisons were corrected by Bonferroni's criteria. VW-patients presented specific craniofacial characteristics and morphology. A marked tendency to the vertical growth pattern was found in VW-patients compared to CG1-CG2 (p<0.001); at the sagittal level, skeletal class II caused by mandibular retrognathism, with a greatly increased ANB angle compared to CG1 (p=0.042). Dental analysis showed that the lower incisor was more retruded and retroclined (p<0.05 in all cases) and the interincisal angulation was increased (p<0.001 (CG2)). At the profile level, an open nasolabial angle (p=0.040; CG1) and a more protruding lower lip with respect to the Sn-Pg plane (p=0.040 (CG1); p=0.044 (CG2)) were observed. VW-patients present particular characteristics in the facial skeletal structures. There is a critical necessity to increase the evidence regarding specific clinical features and orofacial pathology of rare diseases such as VWS, which will help to these minorities to gain access in the future to a better quality of care with precise treatment and diagnostic necessities.

Chondroblastic Variant of Osteosarcoma Mandible-an Intent to Cure.

Osteosarcoma is one of the rarer malignancies that affects the facial skeletal structures. There are only a few retrospective studies discussing the management and outcomes of this malignancy due to the rarity of the disease. Unlike osteosarcoma of long bones, this malignancy has more incidence in patients in the older age group leading to difficulty in the management of this condition but with better outcomes due to the contrasting behavior of this malignancy. Osteosarcoma of the mandible has a longer median survival rate and lesser incidence of distant metastases. Osteosarcomas are more common in the appendicular skeleton, with the most prevalent sites being in the distal femur. Osteosarcoma of the mandible is a rare occurrence with management most commonly being a surgical intervention. Here, we present a 52-year-old female patient who was diagnosed to have osteosarcoma of the mandible treated with hemimandibulectomy and right sternocleidomastoid flap reconstruction with the final histopathology report as osteosarcoma-chondroblastic subtype.

Mandibular and mental foramen – A morphometric study in western Maharashtra

Mandible is the only movable bone of the facial skeleton that forms almost the lower half of the face. In ontogeny, the mandible undergoes substantial morphological and dimensional changes. These changes are largely associated with development of primary and secondary dentition in the human.1 The present study was undertaken to evaluate the anatomical features of mandible i.e. position of mental and mandibular foramina in western Maharashtra and to compare these findings with earlier studies. The findings of this study, variations in size, shape and relationships of dental and lower facial skeletal structure might be useful in providing important data to anatomists, archaeologists, forensic legal experts and maxillo-facial surgeons. Measurements were made on one hundred and ten dry, macerated adult human mandibles of unknown sex from western Maharashtra. Measurements of mental and mandibular foramen from various mandibular anatomical landmarks were taken. In present study it was observed that the most common position of mental foramen is in the line of long axis of 2nd premolar tooth which is universally accepted. Accessory mental foramen was found in one mandible located in line with anterior margin of 1st molar. Keywords: Mandible, Mental foramen, Mandibular foramen, Accessory mental foramen, Dentulous, Edentulous.

Anatomical Basis and Surgical Techniques Employed in Facial Feminization and Masculinization.

Increasingly, facial feminization and masculinization techniques are being employed in the treatment of gender dysphoria. For the facial surgeon, knowledge of the anatomical differences between masculine and feminine facial skeletal structures is of utmost importance. Combining this knowledge with the various surgical and non-techniques that may be employed in order to achieve each patient's goals will allow the facial surgeon to greatly impact the lives of persons of transgender and gender diverse experience. Below, this article discusses these anatomical differences as well as current surgical practices employed in order to masculinize or feminize the face.

Heritability of Facial Skeletal and Dental Characteristics of Monozygotic and Dizygotic Twins Using Cephalometric Analysis and Falconer's Method.

The purpose of this study was to investigate the heritability of facial skeletal and dental characteristics of the monozygotic (MZ) and dizygotic (DZ) twins. The samples consisted of Korean MZ and DZ twins (n = 13 pairs/each twin; 7 pairs of males and 6 pairs of females; mean age, 39 years, respectively). The linear, angular, and ratio variables, which could describe the size and shape of the facial horizontal and vertical, dental, mandible and cranial base structure, were measured. The Falconer's method was used to calculate the heritability (h; close to or below 0, low heritability; close to or above 1, high heritability). In the facial horizontal and vertical aspects, the highest h values were shown at SNA (degree, 1.53), SNB (degree, 2.12), SN-Pog (degree, 2.19), SN-palatal plane angle (degree, 1.29), SN-mandibular plane angle (degree, 1.59), N-ANS/ANS-Me (1.66), and ANS-Me/N-Me (1.62). In the dental aspects, although L1-occlusal plane angle (degree, 1.38) and SN-occlusal plane angle (degree, 2.09) showed high h values, most of the dental variables showed low h values. In the mandible and cranial base, lower gonial angle, mandibular body length, and cranial base angle showed high h values (N-Go-Gn [degree], 1.07; Go-Pog [mm], 0.92; N-S-Ba [degree], 1.51). The descending order of the overall mean h values was the facial horizontal (1.10), facial vertical (0.71), mandible (0.59), cranial base (0.37), and dental characteristics (-0.11). The shape of facial skeletal structure and location of the occlusal plane within skeletal framework was more influenced by genetic factors than environmental factors.

Dentoalveolar changes in post-twin block appliance orthodontic treatment class II dentoskeletal malocclusion

Background: The analysis of cephalometric radiographs provides information about facial skeletal structures, jaw bone-base relationships, incisive-axial inclination relationships, soft tissue morphology, growth direction and pattern, malocclusion classification and the limitations of orthodontic treatments. In class II malocclusion, the mesiobuccal cusp of the permanent maxillary first molar rests between the first mandibular molar and the second premolar. A twin block appliance is recommended to treat Class II dentoskeletal malocclusion with retrognathic mandible characteristics. Purpose: The aim of this study was to analyze the dentoalveolar alterations in class II dentoskeletal malocclusion with retrognathic mandible characteristics after orthodontic treatment with twin block appliance based on a Steiner analysis. Methods: This research constitutes a retrospective study using secondary data derived from the lateral cephalometric radiographs of patients with Class II malocclusion treated with twin block appliance at the Pediatric Dentistry Department of the Oral and Dental Hospital, Universitas Padjajaran, Bandung. The data was analyzed using a T-test for normally distributed paired data. In cases where data was not normally distributed, a Wilcoxon test was employed. Results: The average measurements showed statistically significant dentoalveolar changes among class II malocclusion patients after twin block appliance treatment when analyzed using the paired t-test based on Steiner method cephalometric radiograph analysis (p &lt; 0.05). Conclusion: It is concluded that a twin block appliance is effective in treating class II dentoskeletal malocclusion with a retrognathic mandible based on dentoalveolar changes resulting from Steiner analysis.

A clinical case of single-stage correction of penetration combined orofacial defect with two microsurgical autografts

After surgical treatment for locally advanced oral tumors with resection of soft tissues, mucosal membrane, and facial skeletal structures, there are penetration combined defects, removal of which is a challenge for reconstructive surgeons. Mandibular repair is one of the problems in the correction of combined oral defects. Surgeons use different grafts to remove mandibular defects. One-flap transplantation does not always solve all reconstruction problems and ensure the repair of the mucosal membrane, a soft-tissue component, skin integuments, and facial skeleton. The authors describe a clinical case of successful single-stage correction of penetration combined orofacial defect after resection of the tongue, mouth floor, en bloc resection of the lower jaw and mental soft tissues, bilateral cervical supramyochoroidal lymphadenectomy, stage LCL CM mandibular defect formation after J. Boyd, by using two microsurgical autografts (a peroneal skin-muscle-skin autograft and a radial skin-fascia one) in a 39-year-old female patient clinically diagnosed with carcinoma of the left mandibular alveolar ridge mucosa, Stage IVA (T4аN0M0). The Department of Microsurgery, P.A. Herzen Moscow Oncology Research Institute, Ministry of Health of Russia, has gained experience in comprehensively correcting extensive combined maxillofacial defects with two or more grafts in 27 patients who underwent autografting with a total of 73 flaps. The most functionally incapacitating and life-incompatible defect was removed at Stage 1 of reconstructive treatment. Delayed reconstruction was made after a complex of specialized antitumor therapy and assessment of treatment results in the absence of progressive growth. A great problem during multi-stage defect correction is presented by the lack of recipient vessels after cervical lymphadenectomy, the presence of soft tissue scar changes, trismus, temporomandibular joint ankylosis, contractures and displacement of the edges of the resected mandible, and autografting into the chronically infected area. Single-stage repair, including that using a few microsurgical autografts, is the operation of choice for adequate anatomic and functional rehabilitation, permits the promptest recovery of patients, reduces a postoperative period, and allows them to undergo an antitumor treatment cycle. However, the repair is possible, when the risk of disease progression is low, in specialized centers and when there are trained head and neck surgery and reconstructive microsurgery specialists and anesthesiologists.

Analysis of Age-Related Changes in Asian Facial Skeletons Using 3D Vector Mathematics on Picture Archiving and Communication System Computed Tomography.

PurposeThere are marked differences in facial skeletal characteristics between Asian and Caucasian. However, ethnic differences in age-related facial skeletal changes have not yet been fully established. The aims of this study were to evaluate age-related changes in Asian midfacial skeletons and to explore ethnic differences in facial skeletal structures with aging between Caucasian and Asian.Materials and MethodsThe study included 108 men (aged 20-79 years) and 115 women (aged 20-81 years). Axial CT images with a gantry tilt angle of 0 were analyzed. We measured three-dimensional (3D) coordinates at each point with a pixel lens cursor in a picture archiving and communication system (PACS), and angles and widths between the points were calculated using 3D vector mathematics. We analyzed angular changes in 4 bony regions, including the glabellar, orbital, maxillary, and pyriform aperture regions, and changes in the orbital aperture width (distance from the posterior lacrimal crest to the frontozygomatic suture) and the pyriform width (between both upper margins of the pyriform aperture).ResultsAll 4 midfacial angles in females and glabellar and maxillary angles in males showed statistically significant decreases with aging. On the other hand, the orbital and pyriform widths did not show statistically significant changes with aging.ConclusionThe results of this study suggest that Asian midfacial skeletons may change continuously throughout life, and that there may be significant differences in the midfacial skeleton between both sexes and between ethnic groups.

Volumetric analysis of the pharynx in patients with obstructive sleep apnea (OSA) treated with maxillomandibular advancement (MMA)

Maxillomandibular advancement (MMA) has been reported to be the most effective surgical treatment of obstructive sleep apnea (OSA). Most reports about MMA aim to confirm the efficiency of this treatment modality, but few describe the anatomical changes produced in the pharynx by the surgery. Thus, the objective of the present investigation was to quantify the anatomical changes of the pharynx that occur in patients with OSA after MMA surgery using magnetic resonance (MR). Twenty patients with a polysomnographic diagnosis of OSA participated in the study. All patients were submitted to image acquisition by MR performed during wakefulness. Polysomnography and MR were performed preoperatively and 6months after MMA. Volume analysis (in cubic millimeters) was performed as the sum of the areas multiplied by their thickness, with no intervals between sections. The pharyngeal air space of the region between the hard palate and the base of the epiglottis was divided into a retropalatal (RP) region and a retrolingual (RL) region. Postoperative MR showed a mean volumetric increase of 26.72% in the RP region and of 27.2% in the RL region. MMA increases the air space of the pharynx by expanding the facial skeletal structure to which the soft tissues of the pharynx and tongue are fixed, with a consequent reduction of collapsibility in the presence of negative pressure during inspiration. This reduced possibility of pharyngeal collapse may contribute to the reduction of obstructive events.

Translocación del tercio medio facial en un paciente en edad infantil. Fijación con un nuevo sistema de placas y pines reabsorbibles

Mid-facial translocation, which involves mobilization of the central facial skeletal structures together with soft tissue pedicles, provides generous access to the anterior and central regions of the skull base. One of the drawbacks of this approach in children is skeletal fixation with titanium osteosynthesis plates and screws, which may affect the growth of developing bone. Consequently, a second intervention is required to remove titanium osteosynthesis material, which increases the morbidity of the procedure. Absorbable osteosynthesis material has been marketed since the 1980s as a solution to this problem. We report the case of a 13-year-old female patient diagnosed of chordoma of the clivus. A bilateral mid-facial approach was used with a new system of absorbable plates and pins affixed ultrasonically (SonicWeld ®. KLS Martin, LP, Jacksonville, Florida, USA). The primary approaches to tumors located in the deep facial regions and skull base, the main variations of the mid-facial translocation technique, application of the new SonicWeld ® absorbable system, and the main differences compared to traditional absorbable plates and screws are reviewed.

Toward Characterization of Craniofacial Biomechanics

Surgical reconstruction of craniofacial deformities has advanced significantly in recent years. However, unlike orthopedic surgery of the appendicular skeleton, the biomechanical characterization of the human craniofacial skeleton (CFS) has yet to be elucidated. Attempts to simplify facial skeletal structure into straightforward mechanical device analogies have been insufficient in delineating craniofacial biomechanics. Advanced computational engineering analysis methods offer the potential to accurately and completely define the internal mechanical environment of the CFS. This study developed a finite element (FE) model in the I-deas 10 FEM software package of a preserved cadaveric human CFS and compared the predictions of this model against in vitro strain measurement of simulated occlusal loading forces from a single masseter muscle. The FE model applied shell element modeling to capture the behavior of the thin cortical bone that may play an important role in stabilizing the facial structures against functional loads. In vitro testing included strain measurements at 12 locations for a total of 16 independent channels with less than 150 N of tensile force applied through the masseter muscle into the zygomatic arch origin at 4 different orientations, with 3 trials of 500 recorded data points for each loading orientation. Linear regression analysis yielded a moderate prediction (r = 0.57) between the model and experimentally measured strains. Exclusion of strain comparisons in regions that required greater modeling assumptions greatly improved the correlation (r = 0.70). Future validation studies will benefit from improved placement of strain gauges as guided by FE model predicted strain patterns.

There Is no Conclusive Evidence for a Relationship Between the Structure of the Lower Face and Temporomandibular Disorders

Lateral Cephalometric Characteristics of Malocclusion Patients with Temporomandibular Joint Disorder Symptoms. Hwang CJ, Sung SJ, Kim SJ. Am J Orthod Dentofacial Orthop 2006;129(4):497-503. 4 To investigate the relationship between lower facial skeletal structure and TMJ disorders. Information not available Case-control study

Lateral cephalometric characteristics of malocclusion patients with temporomandibular joint disorder symptoms

There is much controversy about the relationship between temporomandibular joint (TMJ) disorders and the skeletal structures of the lower face. It is not clear whether the disharmony of the facial skeletal structure is caused by the TMJ disorder or vice versa. The aim of this study was to determine the relationship between craniofacial skeletal structures and TMJ disorders by using lateral cephalogram measurements to examine the characteristics of the facial profile of patients with TMJ disorders. Of 111 patients over 18 years of age from the Department of Orthodontics, Dental Hospital, Yonsei University, those showing symptoms of TMJ disorders were chosen as the experimental group (56 patients), and patients without TMJ disorders were chosen as the control group (55 patients). A lateral cephalogram of each subject was taken and traced to confirm the significance of the craniofacial measurements between the experimental group and the control group of Class I (mean ANB angle, 2.89 degrees), Class II (mean ANB angle, 6.32 degrees), Class III (mean ANB angle, -2.02 degrees) patients, who were grouped according to ANB-angle difference. Each experimental subject with a TMJ disorder had a hyperdivergent facial profile, more lingual tilting of the maxillary incisors, and a steeper inclined occlusal plane. There was a significant correlation between the structure of the lower face and the temporomandibular disorder.

Craniofacial deformity in patients with uncorrected congenital muscular torticollis: an assessment from three-dimensional computed tomography imaging.

Congenital muscular torticollis is caused by idiopathic fibrosis of the sternocleidomastoid muscle that restricts movement and pulls the head toward the involved side. Deformation of the craniofacial skeleton will develop if the restriction is not released and result in aesthetic and functional problems. The purpose of this study was to use three-dimensional computed tomography imaging for qualitative and quantitative evaluation of the craniofacial deformity in a series of patients with uncorrected congenital muscular torticollis, and to assess age as a precipitating factor for severity of the deformity. A total of 14 patients from 1 month to 24 years of age were included. The skull images were rotated into standard orientation and reconfigured for evaluation of the cranium, endocranial base, and facial skeletal structures. The midlines of cranial base and facial bone, angle of midline deviation, width of each hemicranium and hemiface, and the orbital index were defined and measured. The results showed that the cranium and cranial base deformation took place as early as in infant stage, with the most prominent change occurring in the posterior cranial fossa. Facial bone asymmetry started to appear after 5 years of age, at which time the mandibular and occlusal abnormalities were observed. The deformity of the orbits and maxilla occurred at an older age, characterized by the deviation and decreased vertical height on the affected side. The severity of the observed deformities increased with age. The angle of midline deviation was 2.48 +/- 1.68 degrees in the cranial base and 3.26 +/- 3.28 degrees on the facial bone. Both of the midline deviations were significantly correlated with age. Compared with the contralateral side, the width of the ipsilateral posterior hemicranium was longer (54.36 +/- 6.72 mm versus 50.81 +/- 6.55 mm), and the width of the ipsilateral lower hemiface was shorter (35.30 +/- 7.27 mm versus 43.49 +/- 11.34 mm). Both differences were statistically significant. Measurement of the orbital index demonstrated a significantly flatter orbit on the ipsilateral side (89.48 +/- 0.11 versus 92.74 +/- 0.08). This study showed that the cranium and cranial base deformity occurred early in patients with uncorrected torticollis, while the facial bone deformity occurred in childhood stage. The cranial and facial deformity became more severe with age. Early release of the muscle restriction is advised to prevent craniofacial deformation.

Negative effect of Hox gene expression on the development of the neural crest-derived facial skeleton.

Diencephalic, mesencephalic and metencephalic neural crest cells are skeletogenic and derive from neural folds that do not express Hox genes. In order to examine the influence of Hox gene expression on skull morphogenesis, expression of Hoxa2, Hoxa3 and Hoxb4 in conjunction with that of the green fluorescent protein has been selectively targeted to the Hox-negative neural folds of the avian embryo prior to the onset of crest cell emigration. Hoxa2 expression precludes the development of the entire facial skeleton. Transgenic Hoxa2 embryos such as those from which the Hox-negative domain of the cephalic neural crest has been removed have no upper or lower jaws and no frontonasal structures. Embryos subjected to the forced expression of Hoxa3 and Hoxb4 show severe defects in the facial skeleton but not a complete absence of facial cartilage. Hoxa3 prevents the formation of the skeleton derived from the first branchial arch, but allows the development (albeit reduced) of the nasal septum. Hoxb4, by contrast, hampers the formation of the nasal bud-derived skeleton, while allowing that of a proximal (but not distal) segment of the lower jaw. The combined effect of Hoxa3 and Hoxb4 prevents the formation of facial skeletal structures, comparable with Hoxa2. None of these genes impairs the formation of neural derivatives of the crest. These results suggest that over the course of evolution, the absence of Hox gene expression in the anterior part of the chordate embryo was crucial in the vertebrate phylum for the development of a face, jaws and brain case, and, hence, also for that of the forebrain.

Location and distribution of epithelial pearls and tooth buds in human fetuses with cleft lip and palate.

The purpose of this study was to establish the location and distribution of epithelial pearls and tooth buds in cleft palate fetuses, relative to the time of palate fusion. The facial skeletal structures, dental laminae, tooth buds, and epithelial pearls were examined in seven spontaneously aborted human fetuses, of which five had unilateral or bilateral cleft lip and palate or cleft palate. The sectioned fetuses were reconstructed by 3D-computer technology. Epithelial pearls were found in four of the investigated cases, of which one was a control specimen. They were located at the margins of the palatal shelves. In the cleft lip and palate cases, the cleft was found in the premaxilla between the first and second incisor tooth. The premaxilla was found to be hypoplastic in both bilateral cleft lip and palate cases and was totally absent in the unilateral cleft lip and palate case. The maxilla was hypoplastic in one case with unilateral cleft lip and palate. In all other specimens, it was developed symmetrically. The results indicate that cleft lip and palate development may occur after the fusion of the frontonasal prominence with the maxillary prominence and the palatal shelves, as well as a nonfusion of the palatal shelves in the secondary palate.

顎関節内障を伴う総義歯患者の形態と機能に関する研究 総義歯こう合再構成に及ぼす影響

There has been no cephalometric study of complete denture wearers that clearly distinguishes those persons with internal derangement of temporomandibular joint from those with normal disk position in relation to mandibular function.Out of a total of sixty complete denture wearers, eighteen patients with normal temporomandibular joint (TMJ) were compared to forty-two patients with documented TMJ internal derangement.The group with internal derangement of TMJ was divided into two groups, one with reduction of disk displacement (twenty-five patients), and the other without reduction of disk displacement (seventeen patients). The patients in these two groups were examined using Magnetic Resonance Imaging (MRI).Lateral, P-A cephalogram, transcranial TMJ radiograph, EMG, and SGG were used to investigate the relationship between TMJ disk displacement and facial skeletal structure and mandibular function. The results were as follows:1. A desirable and functional centric relation could not be achieved among asymptomatic patients with internal TMJ derangement.2. Asymptomatic patients with internal derangement when recording maxillomandibular relation demonstrated considerable variation in the width of the space between the condyle and the fossa and mandibular lateral deviation.

総義歯患者の術前後における顎顔面形態の変化とそしゃく筋活動パターン

It has been said that long-term denture wearers often undergo facial changes as a result of not only occlusal wear of the dentures and residual ridge resorption but also masticatory dysfunction. However, there are no references regarding analysis of morphological change in relation to the functional masticatory muscle activity which is fundamental to an understanding of maxillomandibular relation.The purpose of this study was to investigate whether or not a method of mandibular repositioning that changes the facial skeletal structure can correct mandibular dysfunction. Sixty patients were examined who required denture renewal. Diagnosis of these patients was made, and a clinical method, following standardized treatment, was determined for obtaining correct mandibular position. Patients were evaluated before and after treatment using lateral and P-A cephalogram, transcranial TMJ radiograph, and EMG for bilateral coordination patterns of masticatory muscles.The results were as follows:1. In long-term use of complete dentures, there was a loss of occlusal vertical dimension and the mandible rotated counterclockwisely resulting in an increase in relative prognathism.2. Loss of occlusal vertical dimension coupled with a habitually protruded mandible was corrected by sufficient clinical procedure to correct jaw relation.3. Mandibular function could not be achieved without correction of the facial skeletal structure.