The Influence of Facial Asymmetry on Stress Distributions in Temporomandibular Joints for Patients with Mandibular Prognathism / 医用生物力学

Objective To explore the effects of facial asymmetry on stress distributions in temporomandibular joints (TMJs) for patients with mandibular prognathism. Methods Eight 3D maxillofacial models were established in MIMICS based on cone-beam CT of 4 mandibular prognathism patients with asymmetry and 4 mandibular prognathism patients without asymmetry. Muscle forces and boundary conditions corresponding to the unilateral occlusion (unilateral molar chewing) were applied on the models in ABAQUS. The maximum and the minimum principal stresses of TMJ were chosen for analysis. Results There were significant differences in the maximum and minimum principal stresses at the condyles between the mandibular prognathism patients with and without facial asymmetry under unilateral occlusions (P<0-05). Compared with patients without facial asymmetry, the stresses on the condyle in patients with asymmetry increased by 2-3 times, and the stresses on articular fossa increased by 5-7 times. Among the mandibular prognathism patients with asymmetry, the stresses of the ipsilateral TMJ in patients with temporomandibular disorder (TMD) were significantly higher than those in patients without TMD. Conclusions Facial asymmetry increased the stresses of the articular fossa and condyle in patients with mandibular prognathism. TMD would cause greater stresses in ipsilateral TMJ of the mandibular prognathism patient with asymmetry. Therefore, different treatment strategies should be considered for mandibular prognathism with facial asymmetry.

Application of Polymerase Chain ReactionRestriction Fragment Length Polymorphism (PCRRFLP) Technique in the Analysis of MYO1H Single Nucleotide Polymorphism in Malay Mandibular Prognathism Patients

@#Genetic studies have reported the association between polymorphism in MYO1H with mandibular prognathism. MYO1H is found in skeletal muscle sarcomeres and is expressed in the mandibular jaw cartilage signifying its importance during craniofacial development. This study aimed to characterise the genotype and allele of MYO1H single nucleotide polymorphism (SNP) (rs3825393) and to associate the SNP with mandibular prognathism in Class III skeletal malocclusion. This was a casecontrol study, which involved 57 Malay subjects with 30 Class I (control) and 27 Class III skeletal base patients (case). Cephalometric measurements were taken prior to collection of saliva samples. MYO1H SNP (rs3825383) was genotyped using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Chi-square (χ2 ) test was used to compare genotype and allele frequencies between the groups while Hardy-Weinberg Equilibrium (HWE) was applied to assess distribution of genotype frequency in both classes. MYO1H SNP (rs3825393) did not yield significant association with mandibular prognathism with p = 0.33; OR = 0.66; 95% CI = 0.289~1.518, that was reflected by no significant difference in allele (p > 0.05) and genotype (p > 0.05) frequency between control and study group. Nevertheless, AA genotype depicted the highest frequency in both groups. The genotype distribution in both groups was in concordance with HWE (p > 0.05). Our data showed no association of MYO1H SNP (rs3825393) with mandibular prognathism. Interestingly, we observed Allele A representing the major allele in Malay population. Presence of MYO1H SNP (rs3825393) was detected in samples analysed. Larger number of samples is required to confirm the involvement of MYO1H polymorphisms in mandibular prognathism.

Anesthesia for elective bilateral sagittal slip osteotomy of the mandible and genioplasty in a young man with Klippel-Feil syndrome, Sprengel deformity, and mandibular prognathism

Klippel-Feil syndrome is characterized by congenital fusion of two or more cervical vertebrae, a low hair line at the back of the head, restricted neck mobility, and other congenital anomalies. We report a 16-year-old young man with Klippel-Feil syndrome, Sprengel deformity of the right scapula, thoracic kyphoscoliosis, and mandibular prognathism with an anterior open bite. He was treated with orthodontic treatment and maxillofacial surgery. An anticipated difficult airway due to a short neck with restricted neck movements and extrinsic restrictive lung disease due to severe thoracic kyphoscoliosis increased his anesthesia risk. Due to his deviated nasal septum and contralateral inferior turbinate hypertrophy, we chose awake fiber optic orotracheal intubation followed by submental intubation. Considering the cervical vertebral fusion, he was carefully positioned during surgery to avoid potential spinal injury. He recovered well and his postoperative course was uneventful.

Surgery-first approach for Angle class Ⅲ malocclusion: clinical retrospective analysis of 185 cases / 中华整形外科杂志

Objective@#The purpose of this study was to explore the surgery-first approach in sequential combined orthodontic-orthognathic treatment to shorten total treatment duration and improve the clinical outcome.@*Methods@#This study included 185 patients with Angle classⅢ malocclusion. The patients were divided into 3 different types according to cephalometry analyses and facial features. ①Type Ⅰ: mandibular prognathism or asymmetry mandibular prognathism; ②Type Ⅱ: mandibular prognathism and maxillary retrusion; ③ Type Ⅲ: mild Angle′s Class Ⅲ malocclusion, cross bite in anterior teeth, or normal overlap and overbite relation with midfacial hypoplasia. All of patients received surgery first approach therapy. The surgical procedures were chosen according to different malformation types. Type Ⅰ was treated with the sagittal split ramus osteotomy (SSRO). Type Ⅱ was treated by Le Fort Ⅰmaxillary osteotomy combined with SSRO. Type Ⅲ underwent anterior subapical osteotomy combined pyriform aperture augmentation with biomaterials as well as maxillary anterior orthodontics. All patients received postoperative rapid orthodontic treatment for 6-12 month after 2 weeks of operation. Using the straight arch wire techniques and the class Ⅲ intermaxillary traction, we removed the overcrowding upper and lower teeth, the compensatory axial tilt of teeth, and the deviation of the dental arch and maintained the neutral relationship of the molar. The mandible Hawley retaining devices were used during the maintaining stage.@*Results@#The cases in study acquired satisfactory clinical outcome, which included the shortened overall treatment duration, the significantly improved facial features, the corrected occlusion relationship, and the restored function of mastication and temporomandibular joint. There were some complications as follows: intraoperative fracture (6 cases, 3.24%), the inferior alveolar nerve bundle injury (2 cases, 1.1%), and temporary open-bite that diminished by inter-maxillary elastic distraction one month after operation (19 cases, 10%). All cases in this study accepted postoperative orthodontic treatment. Follow-up time ranged from 6 months to 5 years. The cephalometric analysis results of 126 cases who had complete image data and over 6 months of follow-up showed that hard and soft tissue indexes were restored to normal range after combined orthognathic-orthodontic treatment. The stability of the maxillary and occlusive relationship of SFA(surgery-first approach) was similar to that of the COS(conventional orthodontics-first system) [relapse ratio=(T2-T1)/(T1-T0)×100%]. Over six months of follow-up , SNB and ANB showed that the average relapse ratio were 22% and 19.8%, whereas the relapse angle are less than 2°.@*Conclusions@#The Surgery-first approach could be used to treat most patients with Angle skeletal Class Ⅲ malocclusion, but the indications and the surgical procedures should be noticed and chosen.

Acromegaly: Oral Diagnostician’s Role in Diagnosis: A Case Report.

Acromegaly is an acquired disorder related to overproduction of growth hormone (GH). The condition, though described more than 120 years ago, was only later found to be due to pituitary over secretion and adenomas. It is a rare condition with a tendency toward overgrowth of the mandible, maxillary widening, tooth separation, and skeletal malocclusion which makes its diagnosis important for us dentists. The majority of the cases in the past have been diagnosed by physicians and endocrinologists. Here, we present a case of a 38-year-old male patient who presented with the complaint of increase in the size of lips and forward movement of the jaws since 1 year. Clinical features, radiographic features, and arrival at the diagnosis of Acromegaly with the subsequent referral and treatment are discussed.

Comparison of the Change in the Pharyngeal Airway Space, Tongue and Hyoid Bone Positions according to the Orthognathic Surgical Methods of Mandibular Prognathism

Corrección ortodóncica quirúrgica del prognatismo mandibular / Surgical Orthodontic Treatment for Mandibular Prognathism

Las deformidades dentofaciales son condiciones en las cuales el esqueleto facial es significativamente diferente de lo normal, y afecta gravemente la apariencia facial, en ocasiones requiere de tratamiento quirúrgico. Se presentó una paciente de 25 años de edad, con diagnóstico de prognatismo y macrognatismo mandibular con mordida abierta esqueletal y excesivo crecimiento vertical del mentón que fue sometida a tratamiento ortodóncico quirúrgico por el Grupo Multidisciplinario de Cirugía Ortognática de la provincia Holguín y se siguió desde enero de 2010 hasta septiembre de 2012. Se aplicó terapia ortodóncica fija para corregir apiñamiento y coordinar transversalmente los arcos, se realizó cirugía de retroposición mandibular y ascenso, combinada con mentonoplastia de reducción de altura. Posteriormente, se aplicó tratamiento ortodóncico de finalización y detalles, luego se pasó a fase de contención. Se alcanzó una disminución significativa de los tejidos duros del tercio inferior, longitud mandibular y profundidad facial.

The dentofacial deformities are conditions in which the facial skeleton is significantly different from the normal one, so that facial appearance is seriously affected and requires a surgical therapy, where the patient's handling should be accomplished by a multidisciplinary team. A 25- year- old female patient, who was assisted by a multidisciplinary team of Orthognatic Surgery of Holguín province from January 2010 to September 2012 because of mandibular prognathism and macrognathism with skeletal open bite and excessive vertical growth of the chin. Fixed orthodontic treatment was performed to correct crowding and to coordinate transversally the arches, taking effect a retroposition mandibular surgery and promotion combined with a genioplasty of high reduction. Surgery orthodontic treatment on details was carried out, passing to phase of retention. Significant decrease was achieved the hard tissues of lower third facial mandibular length and depth.

Treatment of a Class III growing patient with mandibular prognathism and severe anterior crossbite / Tratamento de paciente Classe III em crescimento com prognatismo mandibular e severa mordida cruzada anterior

The treatment of growing patients with Class III skeletal pattern represents one of the greatest clinical challenges for the orthodontist. Several treatment protocols have been proposed, almost all involving rapid maxillary expansion and maxillary protraction. However, there are cases where the maxilla is properly positioned in the anteroposterior direction and there is no transverse discrepancy, featuring only a mandibular prognathism. In such cases, when there is a set of favorable factors such as lack of laterognathism and lower mandibular plane angle, a viable option and which could prove quite interesting is the use of orthodontic chin cup during the night, aiming at trying to redirect the forward growth of the mandible. To have success, it is necessary that this procedure involves pubertal growth spurt and is extended to full skeletal maturation. This case was presented to the board of the Brazilian Board of Orthodontics and Dentofacial Orthopedics (BBO) as part of the requirements to become a BBO Diplomate.

O tratamento de pacientes em crescimento com padrão esquelético de Classe III representa um dos maiores desafios clínicos para o ortodontista. Vários protocolos de tratamento têm sido propostos, quase todos envolvendo expansão rápida da maxila e protração maxilar. Porém, existem casos onde a maxila está corretamente posicionada no sentido anteroposterior e não há discrepância transversa, caracterizando apenas um prognatismo mandibular. Nesses casos, quando há um conjunto de fatores favoráveis, tais como ausência de laterognatismo e menor ângulo do plano mandibular, uma opção viável e que pode se mostrar bastante interessante é o uso noturno da mentoneira, com o objetivo de tentar redirecionar o crescimento anterior da mandíbula. Para que haja sucesso, é necessário que esse procedimento envolva o surto de crescimento da puberdade e seja estendido até a completa maturação esquelética. O presente caso clínico foi apresentado à diretoria do Board Brasileiro de Ortodontia e Ortopedia Facial (BBO), como parte dos requisitos para a obtenção do titulo de Diplomado pelo BBO.

Skeletal Stability after Orthognathic Surgery in Severe Skeletal Class III Malocclusion Patients according to Changes in Anteroposterior Discrepancy and Occlusal Planes

Initial Stability after Bilateral Sagittal Split Ramus Osteotomy Application in Patients with Mandibular Prognathism

Genetic influence and heritability in mandibular prognathism of Korean families

INTRODUCTION: This study examined the genetic influence of mandibular prognathism epidemiologically in Korean families. MATERIALS AND METHODS: Over a 5-year period from 2005 to 2009, a questionnaire with a pedigree chart was given to 100 (male 51, female 49) probands with skeletal Class III mandibular prognathism, who had undergone orthognathic surgery in Samsung Medical Center. RESULTS: The average age of the probands was 22.1. The average SNA, SNB and ANB angles of the probands were 81.2degrees, 84.1degreesand -2.9degrees, respectively. A total of 2729 (male 1,354, female 1,375) family members were examined, and the affected ratio of the families was 3.5% with no significant difference between genders. 45% of families had at least one member with a Class III malocclusion other than the proband. The affected ratio of the first-degree relatives (10.9%) was significantly higher than those of the second-degree (3.3%) and third-degree (1.9%) relatives. The affected ratio of the total relatives from the male probands (4.2%) was significantly higher than that of the female probands (2.8%). Heritability (h2, Falconer'method) was estimated to be 29.8% (0.298+/-0.059) in first-degree relatives. CONCLUSION: These results showed the significant influence of mandibular prognathism with relatively low heritability in first-degree relatives in Korean families of probands, who had undergone orthognathic surgery to correct a skeletal Class III malocclusion.

Postura craneocervical en pacientes infantiles después de la terapia con mentonera: un estudio piloto / Craneocervical posture in children after treatment with chincap: a pilot study

Introducción: el propósito del presente estudio fue describir los cambios en la postura craneocervical en unapoblación infantil con clase II esquelética por prognatismo mandibular, luego de la utilización de mentonera con placa de acetato inferior para levantar la mordida. Métodos: la muestra consistió de once niños (siete niñas y cuatro niños). A cada niño le fueron tomadas tres radiografías cefálicas laterales en posición natural de cabeza (mirando de frente a un espejo), con ligero contacto oclusal. La primera radiografía (T1) fue tomada antes de iniciar la utilización de la mentonera, la segunda (T2), cuatro meses después de su uso y la tercera (T3), cuatro meses después de retirada. Para el análisis se emplearon medidas lineales y angulares, se realizó análisis descriptivo de las variables y se utilizaron las pruebas de normalidad (Shapiro-Wilk) y Friedman. Resultados: el análisis estadístico no mostró diferencias significativas en ninguna de las variables analizadas, y en ninguno de los momentos evaluados. Conclusión: a pesar de la gran variabilidad individual en la postura craneal, cervical y craneocervical de los niños evaluados, en general no se observaron en esta muestra cambios significativos en la columna cervical, luego del tratamiento con mentonera y placa de acetato inferior que levantaba la mordida.

Introduction: the aim of this study was to describe the changes in the craniocervical posture in children with skeletal class II malocclusion (prognathic mandible) after wearing chincap with lower occlusal bite plane. Methods: the sample consisted of eleven children (7 girls and 4 boys). Three lateral cephalic radiographs were taken for each child with the head in natural position (“mirror position”), with light occlusal contact. The first radiograph (T1) was taken before wearing the chincap, the second (T2) was taken four months after wearing the appliance and the third (T3) was taken four months after removing the chincap. Specific angular and linear dimensions were used, the comparison within the group was performed using Descriptive Analysis and the Normality (Shapiro-Wilk) y Friedman Signed Rank Test. Results: statistical analysis didn’t show significant changes in any of the angular and linear measurements analyzed nor at any of the times studied. Conclusion: even though there is a great individual variability in the cranial, cervical and craniocervical posture of the tested children, in general, there were nostatistical significant changes in cervical posture after treatment with chincap and lower occlusal bite plane.

Study on the Anatomical Position of Mandibular Canal Using Computed Tomography in Mandibular Prognathism Patients

Cone-beam computed tomography measurement of the position of the inferior alveolar nerve canal in mandibular prognathism

BACKGROUND AND OBJECTIVES: To determine the anatomic position of the inferior alveolar nerve (IAN) canal in patients with mandibular prognathism using the cone-beam CT (CBCT). MATERIALS AND METHODS: Fifty rami from 25 patients were evaluated. The images were taken by i-CAT and reconstructed 3-dimensionally using the Simplant 11 program. The linear distances between the IAN canal to the buccal cortex (a, a* and a**), from the IAN canal to the alveolar crest (b and b*) and the anterior margin (b**) and finally the buccal cortical thickness (c, c* and c**) were measured at three reference planes (VP, OP and HP). RESULTS: On the left side, the average distance of a, b and c were 7.12, 15.96 and 3.60 mm on the VP plane, respectively. On the OP, the distance of a*, b* and c* was 6.11, 8.83 and 2.63 mm. For the HP, the distance of a**, b** and c** was 4.84, 10.11 and 2.30 mm. On the right side, the distance of a, b and c, on the VP, was 7.10, 16.13 and 3.42 mm, respectively. On the OP, the distance of a*, b* and c* was 4.77, 8.75 and 2.68 mm. On the HP, the distance of a*, b* and c** was 4.55, 9.84 and 2.38 mm. Regarding the difference between genders, the distance in male's was longer than female's on the VP (p=0.019), and was thicker in males than females on the HP (p=0.002). CONCLUSION: The CBCT data provided accurate information about the location and course of the IAN.

Cone-beam computed tomography measurement of the position of the inferior alveolar nerve canal in mandibular prognathism

BACKGROUND AND OBJECTIVES: To determine the anatomic position of the inferior alveolar nerve (IAN) canal in patients with mandibular prognathism using the cone-beam CT (CBCT). MATERIALS AND METHODS: Fifty rami from 25 patients were evaluated. The images were taken by i-CAT and reconstructed 3-dimensionally using the Simplant 11 program. The linear distances between the IAN canal to the buccal cortex (a, a* and a**), from the IAN canal to the alveolar crest (b and b*) and the anterior margin (b**) and finally the buccal cortical thickness (c, c* and c**) were measured at three reference planes (VP, OP and HP). RESULTS: On the left side, the average distance of a, b and c were 7.12, 15.96 and 3.60 mm on the VP plane, respectively. On the OP, the distance of a*, b* and c* was 6.11, 8.83 and 2.63 mm. For the HP, the distance of a**, b** and c** was 4.84, 10.11 and 2.30 mm. On the right side, the distance of a, b and c, on the VP, was 7.10, 16.13 and 3.42 mm, respectively. On the OP, the distance of a*, b* and c* was 4.77, 8.75 and 2.68 mm. On the HP, the distance of a*, b* and c** was 4.55, 9.84 and 2.38 mm. Regarding the difference between genders, the distance in male's was longer than female's on the VP (p=0.019), and was thicker in males than females on the HP (p=0.002). CONCLUSION: The CBCT data provided accurate information about the location and course of the IAN.

Transverse change of the proximal segment after bilateral sagittal split ramus osteotomy in mandibular prognathism using computed tomography

Soft tissue changes associated with advancement genioplasty in skeletal class III individuals receiving mandibular set-back surgery / 대한치과교정학회지

PURPOSE: The purpose of this study was to assess the hard and soft tissue changes associated with mandibular bilateral sagittal split osteotomy and genioplasty. METHODS: This is a retrospective study of 40 patients who underwent either bilateral sagittal split osteotomy for mandibular setback (BSSO group, n = 20) or in combination with advancement genioplasty (Genio group, n = 20). Lateral radiographs, were taken before and immediately after surgery, and at least 6 months after surgery. RESULTS: Comparing hard and soft tissue changes between the BSSO group and Genio group, there were significant differences in the lower incisor, soft tissue B point (B'), and soft tissue Pogonion (Pg') (p < 0.5). The mean ratio of hard and soft tissue changes for B/B', Pg/Pg', and Menton/soft tissue Menton after surgery in the BSSO group was 0.997, 0.965, and 1.022 respectively, and 0.824, 0.602, and 0.887 respectively in the genio group. Significant differences were found between the two groups. There were significant differences in lip thickness (B-B', Pg-Pg') in the Genioplasty group between pre and postsurgery, but not in the BSSO group. Pogonion to Labrale inferior and B' had a correlation coefficient of 0.833, 0.922, respectively for the BSSO group, and 0.775, 0.799 for the Genio group. CONCLUSIONS: The results indicate that there is a significant difference between bilateral sagittal split osteotomy with or without genioplasty in the lower facial esthetics values. The combination of mandibular setback and genioplasty had a smaller change in soft tissue thickness of the symphysis area after surgery than that of mandibular setback only.

Treatment of transverse deficiency of maxilla with sarpe in cleft palate

Patients who have repaired cleft lip and palate generally undergo restriction of maxillary growth. Concave facial profile is often exhibited with relatively normalized mandible. Horizontal and sagittal deficiency of the maxilla could cause anterior and posterior crossbites. In growing patients, orthodontic and orthopedic treatment is acceptable with maxillary expansion and protraction. However, surgical approach has to be accompanied with orthodontic treatment in skeletally matured patients. We used SARPE and BSSRO to expand the constricted maxilla and retract the mandible in a patient who had cleft palate repaired in infancy. Through SARPE, orthodontic treatment and BSSRO, we sufficiently expanded the maxillla and improved facial profile.

Treatment of transverse deficiency of maxilla with sarpe in cleft palate

Patients who have repaired cleft lip and palate generally undergo restriction of maxillary growth. Concave facial profile is often exhibited with relatively normalized mandible. Horizontal and sagittal deficiency of the maxilla could cause anterior and posterior crossbites. In growing patients, orthodontic and orthopedic treatment is acceptable with maxillary expansion and protraction. However, surgical approach has to be accompanied with orthodontic treatment in skeletally matured patients. We used SARPE and BSSRO to expand the constricted maxilla and retract the mandible in a patient who had cleft palate repaired in infancy. Through SARPE, orthodontic treatment and BSSRO, we sufficiently expanded the maxillla and improved facial profile.

The Correction of Mild Mandibular Prognathism Using Mandibular Anterior Segmental Osteotomy

PURPOSE: For a minor degree of mandibular prognathism, mandibular anterior segmental osteotomy (ASO), usually extracting the bilateral premolars, has been performed frequently to correct malocclusion of the anterior teeth. Preoperative planning using cephalometry and a dental model is very important for such a orthognathic surgery. Depending on the specific preoperative mock surgery with the dental model, ASO, with ipsilateral unitooth extraction, is defined to be feasible and performed for ten patients. The comparisons of its preoperative and postoperative analysis of clinical photographs, dental casts, and lateral cephalograms, for soft tissue profiles, skeletal and dental relationships are described in the following, and its clinical applications are noted. METHODS: From March 1, 2004, to March 31, 2006, We performed 10 mandibular ASO by extraction of ipsilateral unitooth to improve their lower facial profiles and the lip relationships. Patient age ranged from 19 to 33 years, with a mean age of 25.6 years. Two were males and eight were females. RESULTS: All patients were satisfied with aesthetic and occlusal changes postoperatively. Significant and persistent decrease in the SNB and interincisal angle were observed in the postoperative cephalometries. The soft tissue profiles also were improved and near Ricketts's esthetic line. Other combined procedures include nine genioplasties, two rhinoplasties, and one blepharoplasty. One patient complained of transient unilateral inferior mental nerve paresthesia. There were no other significant complications or relapses throughout the follow-up period(6-20 months). CONCLUSION: Mandibular ASO, extracting the ipsilateral unitooth, was performed for ten patients to correct mild mandibular prognathism. The amount of setback of the mandibular anterior portion was 2 to 3mm, and satisfactory results were obtained combined with genioplasties.