Lateral Cephalometric Radiographs Research Articles

Assessment of the Effect of Chin Augmentation with Hyaluronic Acid Filler on Facial Soft Tissues Using Lateral Cephalometric Radiograph

Assessment of the Effect of Chin Augmentation with Hyaluronic Acid Filler on Facial Soft Tissues Using Lateral Cephalometric Radiograph

Lateral Cephalometric Analysis of Nasal Morphology in Patients Visiting Nishtar Institute of Dentistry

Nasal morphology is the keystone of facial aesthetics. Being the most prominent part of the face, the shape and position of the nose greatly influence the facial profile and nasal soft tissue thickness also plays a vital role in orthodontic diagnosis and treatment planning. Objective: To evaluate the soft tissue nasal morphology in individuals presenting with different skeletal patterns such as skeletal class 1 and skeletal class 2 jaw relationship. Methods: It was Comparative Cross-sectional study conducted in Orthodontics Department of Nishtar Institute of Dentistry for the period of six months (5th Mar 2020 to 6th Jun 2021). Study sample consisted of Lateral cephalometric radiographs of 65 subjects. Age range of sampled subjects was 19-26 years (mean age 20.93). The sample was divided into two groups on basis of the Skeletal jaw relationship as class-1 and class-2. An Independent t-test was applied for evaluation of the difference in lateral nasal morphology between both groups. Results: Notable differences were found between skeletal class 1 and skeletal class 2 groups for the prominence of the mandible and Linear distance between soft tissue Pogonion and Pronasale. Considerable differences in measurements of nasal depth, nasofrontal angle, nasal tip projection angle, nasofacial angle and nasomental angle were found. Conclusions: It is concluded that nasal morphology was greatly influenced by not only the underlying skeletal jaw relationship yet other factors e.g., dentition along with soft tissue thickness were also responsible for nasal morphology differences among various skeletal patterns. Gender dimorphism also exists for various nasal features.

Anterior Maxillary Distraction Osteogenesis With Bone-borne Intraoral Buccal Devices for Maxillary Hypoplasia With Cleft Lip and Palate.

Anterior maxillary distraction osteogenesis (AMDO) surgery for cleft lip and palate involves distraction of a segment of the anterior maxilla and advancement using 2 intraoral buccal bone-borne distraction devices. The anterior part of the maxilla is advanced anteriorly with less relapse which increases maxillary length and does not affect speech. We aimed to evaluate the effects of AMDO, including lateral cephalometric changes. Seventeen patients who had undergone this procedure were included in this retrospective study. The distractors were activated by 0.5mm twice a day after a 3-day latency period. Lateral cephalometric radiographs were evaluated preoperatively, after distraction and removal of distractors, which were compared using the paired Student's t test. Anterior maxillary advancement was obtained in all patients with a median of 8.0mm. Complications included nasal bleeding and loosening of distractors; however, there was no tooth damage or abnormal movement. The mean sella-nasion-A point (SNA) angle increased significantly, from 74.91° to 79.66°, the A point-nasion-B point angle from -0.38° to 4.34°, and the perpendicular line from nasion to Frankfort Horizontal (NV)-A point from -5.11 to 0.08mm. The mean anterior nasal spine-posterior nasal spine length increased significantly from 50.74 to 55.10mm, and the NV-Nose Tip from 23.59 to 26.27mm. The mean relapse rate of NV-A was 11.1%. AMDO with bone-borne distractor resulted in less relapse and effectively corrected the maxillary retrusion.

Investigation of the Relationship of Impacted Maxillary Canines with Orthodontic Malocclusion: A Retrospective Study.

Impacted canines, which play an important role in smile aesthetics and functional occlusion, can lead to dental and skeletal malocclusions. In this study the aim was to evaluate the relationship between impacted maxillary canines and malocclusion. A total of 151 patients comprising 101 females and 50 males aged between 13 and 33 years were included. The groups were divided based on age, gender, skeletal and dental classification, and sector classification. Angular and linear measurements were performed on lateral cephalometric and panoramic radiographs. In panoramic radiographs, the vertical distance of the impacted canine to the occlusal plane and the angle between it and the bicondylar plane were measured and sector classification was performed according to its relationship with the root of the lateral incisor. Skeletal classification was performed according to the ANB angle on lateral cephalometric radiographs and dental classification by molar relationship via the intraoral photographs. The Chi-square test analyzed independent qualitative and quantitative data using Kruskal-Wallis and Man-Whitney U tests. The statistical significance level was accepted as p < 0.05. According to the intraclass correlation test, an excellent positive correlation was found with 0.985 for canine distance and 0.993 for canine angle between the repeated measurements. The impaction of the maxillary right canine was significantly highest in females and lowest in males. The impacted canine angle was significantly highest in sector 1 and lowest in sector 4. Distance to the occlusal plane was significantly higher in dental Class II and sector 4. It was observed that there was a considerable relationship between impacted maxillary canines and malocclusion; bilateral impacted canines were more frequent in skeletal Class III, and the distance of impacted canines to the occlusal plane increased while their angles decreased both in dental Class II and from sectors 1 to 4.

Automated Sagittal Skeletal Classification of Children Based on Deep Learning.

Malocclusions are a type of cranio-maxillofacial growth and developmental deformity that occur with high incidence in children. Therefore, a simple and rapid diagnosis of malocclusions would be of great benefit to our future generation. However, the application of deep learning algorithms to the automatic detection of malocclusions in children has not been reported. Therefore, the aim of this study was to develop a deep learning-based method for automatic classification of the sagittal skeletal pattern in children and to validate its performance. This would be the first step in establishing a decision support system for early orthodontic treatment. In this study, four different state-of-the-art (SOTA) models were trained and compared by using 1613 lateral cephalograms, and the best performance model, Densenet-121, was selected was further subsequent validation. Lateral cephalograms and profile photographs were used as the input for the Densenet-121 model, respectively. The models were optimized using transfer learning and data augmentation techniques, and label distribution learning was introduced during model training to address the inevitable label ambiguity between adjacent classes. Five-fold cross-validation was conducted for a comprehensive evaluation of our method. The sensitivity, specificity, and accuracy of the CNN model based on lateral cephalometric radiographs were 83.99, 92.44, and 90.33%, respectively. The accuracy of the model with profile photographs was 83.39%. The accuracy of both CNN models was improved to 91.28 and 83.98%, respectively, while the overfitting decreased after addition of label distribution learning. Previous studies have been based on adult lateral cephalograms. Therefore, our study is novel in using deep learning network architecture with lateral cephalograms and profile photographs obtained from children in order to obtain a high-precision automatic classification of the sagittal skeletal pattern in children.

Evaluation of Impacted Canines Utilizing Three Radiographic Methods in Orthodontic Patients in Benin City, Nigeria

Background: Impacted canines are one of the most commonly missing teeth in the oral cavity and traditionally, two dimensional (2-D) radiographic views have been utilized in localizing such teeth. The introduction of the 3-D Cone Beam Computed Tomography was to enable localization in three dimensions. A reliable and concise radiographic technique will enable proper diagnosis of the type and extent of impaction and aid in choosing the proper treatment and also monitor treatment progression.&#x0D; Aim: The aim of this study was to evaluate impacted canines in orthodontic patients utilizing three radiographic methods in Benin City, Nigeria.&#x0D; Methods: In this prospective study, 34 pre-orthodontic patients (30 with unilateral and 4 with bilateral impactions) and a total number of 38 impacted canines were selected. The Lateral Cephalometric radiograph was used to determine the patients’ orthodontic problem. Three groups of participants were selected and identified based on the radiographic method utilized; with group 1, the periapical / Occlusal group (POCC, n=13); group 2, the Orthopantomogram group (OPG, n=13). The third group was the Cone Beam Computed Tomography group (CBCT, n=12). Impacted canines were detected and the position assessed and classified utilizing three radiographic methods into classes I to VI. The differences between groups and correlations between variables were determined with the student’s t-test and the Spearman correlation coefficient respectively. Significant values of P&lt;0.05 were applied.&#x0D; Results: The mean age of participants was 18.29±6.15 years. A total number of 30(78.9%) impactions were seen in the upper jaw and 8(21.1%) in the lower jaw. Bilateral impactions were seen in the upper jaw of 3(7.9%) patients and 1(2.6%) in the lower jaw respectively. The position of the canines could only be identified clearly in classes I and II from group 1. Group 2 (OPG) was the least definite in identifying accurately the position of the canines. The CBCT (Group 3) did not record any impaction in the lower jaw. Consecutive paraxial cuts at 1.5mm interval on the CBCT showed the position of the canines to be in Class I in 6(50%), class II in 3(25%) and classes III in 2(16.7%) and VI in 1(8.3%) respectively in the upper jaw.&#x0D; Conclusion: The CBCT appears to be the most reliable method of identifying the position and depth of impacted canines.

Relationship Between Crown-to-Root Angulation of Maxillary Central Incisor and Lower Lip Line In Different Malocclusions

Collum angle, supplementary angle between longitudinal axis of crown-to-root, is an important consideration in patients receiving orthodontic treatment This angulation in labio-lingual direction is a key factor for proper occlusion and is greatly affected by lower lip line levels in different malocclusions. Objective: To find the relationship between collum angle of maxillary central incisor and lower lip line in patients presenting with different malocclusions. Methods: Cross-sectional, Comparative Study conducted in Orthodontics department of Nishtar Institute of Dentistry, Multan.From September 2020 to February 2021. Lateral cephalometric radiographs of 105 patients (39 males and 66 females)were selected with age range of 9-30 years. Patients were divided in 4 groups i.e Class I, Class II div I, Class II div II and class III. Collum angle was measured along with assessing lower lip-line level with central incisor. One-way ANOVA test was applied to compare level of lower lip and collum angle. Results: Mean value of collum angle was 5.82˚±5˚ for class I, 3.68˚ ± 9˚ for class II div I, 11.7˚± 5˚ for class II div II, and 6.88˚± 7 ˚for class III. Collum angle of maxillary central incisor was greatly increased in patients with class II div II malocclusion than other groups. Conclusions: Collum angle found to be highest in class II div II malocclusion group. Lower lip line resting on middle third level of maxillary central incisor crown in div II group explains this exceeding value of collum angle

Skeletal Maturity Assessment using Mandibular Canine Calcification Stages

Objective: To determine the correlation between cervical vertebral maturation stages on a lateral cephalo-gram and Dimerijan canine calcification stages on an Orthopan-tomogram for assessment of skeletal maturity&#x0D; Study Design: Cross-sectional study.&#x0D; Place and Duration of Study: Orthodontics Department, Armed Forces Institute of Dentistry (AFID), Rawalpindi Pakistan, from Dec 2021 to Apr 2022.&#x0D; Methodology: The subjects of either gender, aged 9 to 16 years, in good physical, mental and oral health were included in the study. Two radiographs, a lateral cephalogram and Orthopantomogram, were taken for each patient. Hassel and Farman and Demirjian stages were used to asses skeletal maturity and canine classification, respectively.&#x0D; Results: The mean age of the sample was 13.29±1.86 years. The Hassel and Farman CVM stages on a lateral cephalometric radiograph and Dimerijan canine calcification stages on a panoramic radiograph showed a significant positive correlation (r= 0.785, p= 0.000)&#x0D; Conclusion: There is a high correlation between CVM stages by Hassel and Farman and Dimerijan canine calcification stages to assess skeletal maturity. Therefore, any of these radiographs can be employed to assess the skeletal maturity status of the patient without exposing the patient to additional radiographic radiation.Keywords: Cervical vertebral maturation (CVM) stages, Canine calcification stages, Dental maturity, Skeletal maturity.

A study of method to find the centre of rotation of the maxilla

ABSTRACT Purpose In the previous methods used for finding the centre of rotation (CR) of the maxilla, no consideration was given to changes in shape due to growth. This study aimed to correct morphological changes due to growth, development, and treatment to find the centre of spiral similarity (CS). Materials and methods The CR and CS were calculated for 106 patients (35 males and 71 females) who were examined at Osaka Dental University Hospital’s Department of Orthodontics for the primary complaint of malocclusion and had lateral cephalometric radiographs at the initial and after treatment or for follow-up. Results A formula that enables calculation of both the CR obtained by the previous method and the CS obtained with the similarity transformation taken into consideration was proposed, and when the CR and CS were compared with all 106 patients, the dispersion of the CS was found to be less than that of the CR. Conclusion The authors propose the use of the CS for the evaluation of the maxilla. In addition, a formula for calculating the CS has been developed and has been implemented using computer software. Moreover, the resulting method is simpler, more rapid, and more reliable than the previous methods.

A Cephalometric Analysis Assessing the Validity of Camper's Plane to Establishing the Occlusal Plane in Edentulous Patients.

Complete denture fabrication requires multiple clinical and laboratory steps. One of the most critical clinical steps is establishing an anatomical occlusal plane based on hard and soft tissue references. The aim of this study was to determine whether age or gender affects the level of the Ala-Tragus plane to establish which reference point on the Tragus should be used when fabricating the occlusal plane in edentulous patients. Clinical photographs and lateral cephalometric radiographs with complete dentitions were taken from 58 volunteers at the DMD clinic at the University of Kentucky. Each photograph was superimposed over its corresponding cephalometric image. An analysis was conducted to establish the angle of the occlusal plane relative to the Ala-Tragus landmarks; this data was then grouped according to age and gender. The analysis shows that age and gender did not significantly affect where the Camper's plane should be approximated for complete denture treatment. However, it was found that the most parallel line to the occlusal plane was Ala's inferior border to the 'Tragus's inferior border. It should be noted that the volunteers' skeletal classification was significantly related to a Cl III malocclusion tendency. Still, with this new information, functionality and esthetics can be more adequately addressed for patients undergoing complete denture treatment. Given our results, we suggest redefining the 'Camper's plane with a line extending from 'Ala's inferior border to the 'Tragus's inferior border instead of the superior border. Further consideration should be taken if the patient is a skeletal CL III malocclusion.

Dentoalveolar compensation in various skeletal malocclusion groups in district solan population: A cephalometric study

: To assess the position and inclination of upper and lower incisors and bases in different groups of skeletal malocclusions. 45 pretreatment lateral cephalometric radiographs were included. They were divided into his three groups of skeletal class I, class II, and class III. A variety of linear and angular measurements were used to assess both the position and inclination of the maxillary and mandibular bases, incisors, and the relationship between the incisors. There was a significantly stronger correlation between anterior-posterior skeletal mismatch and maxillary alveolar bone compensation in skeletal classes I, II, and III. Except for maxillary vertical skeletal discrepancy (MP-SN) and alveolar compensation, there was a weak correlation between maxillary and mandibular vertical skeletal discrepancy and alveolar compensation. The anterior-posterior position of the skeletal jaw had a greater effect on alveolar bone changes than the vertical inclination of the skeletal jaw in the Grad variant. There may be a relationship between alveolar bone changes and skeletal anteroposterior and vertical position, inclination and intermaxillary relationship.

Preciseness of artificial intelligence for lateral cephalometric measurements.

The aim of the study was to assess the accuracy and efficiency of anew artificial intelligence (AI) method in performing lateral cephalometric radiographic measurements. A total of 200lateral cephalometric radiographs were assessed for quality and included. Three methods were used to perform the cephalometric measurements: (1) the AI method using WebCeph software (AssembleCircle Corp., Gyeonggi-do, Republic of Korea), (2)the modified AI method using WebCeph software after manual modification of the landmarks' position, and (3)using OnyxCeph software (Image Instruments GmbH, Chemnitz, Germany) by manual landmark identification and digital measurements generation. The results of the measurements produced by the three methods were compared, in addition to comparing the time required for the measurements' generation required for each method. Statistically significant differences were detected between the measurements resulting from the three used methods. Fewer differences were detected between the modified AI method and the OnyxCeph method. The AI method produced the measurements the fastest followed by the modified AI method and then the OnyxCeph method. Considering the used AI software, AI followed by manual tuning of the landmarks' position might be an accurate method in lateral cephalometric analysis. AI alone is still not fully reliable at locating the different landmarks on the lateral cephalometric radiographs.

Deep convolutional neural network-the evaluation of cervical vertebrae maturation.

This study aimed to automatically determine the cervical vertebral maturation (CVM) processes on lateral cephalometric radiograph images using a proposed deep learning-based convolutional neural network (CNN) model and to test the success rate of this CNN model in detecting CVM stages using precision, recall, and F1-score. A total of 588 digital lateral cephalometric radiographs of patients with a chronological age between 8 and 22years were included in this study. CVM evaluation was carried out by two dentomaxillofacial radiologists. CVM stages in the images were divided into 6 subgroups according to the growth process. A convolutional neural network (CNN) model was developed in this study. Experimental studies for the developed model were carried out in the Jupyter Notebook environment using the Python programming language, the Keras, and TensorFlow libraries. As a result of the training that lasted 40 epochs, 58% training and 57% test accuracy were obtained. The model obtained results that were very close to the training on the test data. On the other hand, it was determined that the model showed the highest success in terms of precision and F1-score in the CVM Stage 1 and the highest success in the recall value in the CVM Stage 2. The experimental results have shown that the developed model achieved moderate success and it reached a classification accuracy of 58.66% in CVM stage classification.

Vertical Facial Changes After 6 Months of Fixed Orthodontic Treatment

Background: The use of fixed orthodontic appliances can change the vertical face due to the movement of the molars. A lateral cephalometric radiograph was used to assess the outcome of the treatment. Analysis of the vertical facial changes was performed by observing the changes of the MP-SN angle. Objective: The purpose of this study was to determine whether there were differences in the vertical face before and after 6 months of fixed orthodontic treatment using the Steiner method. Methods: This study used a case-control design comparing groups before and after 6 months of fixed orthodontic treatment. The sample in this study amounted to 5 people. The vertical measurement of the face is carried out at the MP-SN angle, namely the angle formed by the MP (Mandibular Plane – Go-Gn) line and the SN (Sella-Nasion) line. The data analysis was performed with the program SPSS Version 25. Result: There were no significant changes in the study (p&gt;0.05). The average change is 1.2º. Of the 5 patients, 4 patients (80%) experienced a decrease in MP-SN angle, while 1 patient (20%) experienced an increase in the MP-SN angle. Conclusion: There was no significant change in facial vertical changes before and after 6 months of fixed orthodontic treatment at RSGM UMY. The decrease in the MP-SN angle is caused by the intrusion of the molars which causes the mandible to rotate counterclockwise. The increase in the MP-SN angle is due to the distalization of the molars, resulting in a clockwise rotation of the mandible.

Does Postpartum Hypopituitarism Influence the Craniofacial Pattern? A Case-Control Study with Sheehan&amp;#8217;s Syndrome Patients

This study aimed to assess the craniofacial morphologic aspects of Sheehan’s syndrome (SHS) patients.An observational study was performed with 19 women diagnosed with SHS and 19 controls matched by age and sex. Lateral cephalometric radiographs were obtained, and 30 linear and angular measurements were analyzed using the Radiocef Studio 2 software. The mean age of patients was 65.47 ± 10.19 years. The main findings were propositioned maxilla (52.63 %) and mandible (52.63 %) relative to the cranial base, mandibular prognathism in 73.68 %, deep growth pattern in 42.1 %, increased mandibular plane in 36.84 %, and reduction in anterior facial height. The SHS group showed statistically significant differences in SNB (p=0.026), N-Me (p=0.006), soft palate length (p=0.011), and Ena-Me (p<0.001) in comparison with controls. The standard deviation score analysis revealed altered values in relation to total maxillary and mandibular lengths. SHS showed altered craniofacial morphology, characterized by maxillo- mandibular prognathism, brachyfacial type, increased mandibular plane, and reduction in soft palate length. This study reports novel findings in SHS.

A survey of patient contact shielding in dental teaching hospitals in the UK

A high volume of dental imaging is carried out each year. In the UK, guidance on the use of patient contact shielding for these investigations is published by the British Institute of Radiology (BIR) and in a document jointly produced by the Faculty of General Dental Practice and Public Health England (FGDP/PHE). Both these sources of guidance have been updated recently and patient contact shielding is no longer recommended for most imaging settings in dental radiology. It is unclear whether radiology departments at dental teaching hospitals in the UK are aware of these sources of guidance, and how this relates to clinical practice within these departments. A survey was carried out exploring the awareness of current guidelines and clinical practice at dental teaching hospitals in the UK. The survey was sent to a representative at 17 different dental teaching hospital radiology departments. Responses were received from 11 departments. The range of intra-oral and extra-oral imaging carried out at these departments was comparable. Ten departments were aware of the existence of national guidelines for patient contact shielding, however only four were specifically aware of the recent BIR guidelines and only four were specifically aware of the FGDP/PHE guidelines. No department was aware of both sets of guidelines. No departments used thyroid protection for bitewing, periapical, lower 45 degree occlusal, panoramic or lateral cephalometric radiographs. Six departments sometimes or always used thyroid protection for upper standard occlusal imaging. Two departments used thyroid protection for cone beam CT imaging. No departments routinely used lead aprons on patients for dental imaging. In conclusion, radiology departments at dental teaching hospitals in the UK do not use patient contact shielding for most imaging situations in dental radiology. There is mixed awareness of current national guidelines, but the reported clinical practice aligns well with the current guidelines.

Establishing cephalometric norms of upper and lower lips to Rickett’s E-line in the Malay female population of Kuantan city: a pilot study

The purpose of the study was to determine the cephalometric norms of upper and lower lips to the Rickett’s E-line in the Malay female population of Kuantan city, and to compare it with the Caucasian norms. This was a retrospective study involving 40 pre-existing lateral cephalometric radiographs taken from October 2017 to October 2021 of skeletal Class I females of pure Malay ethnic group aged 20 to 40 retrieved from two private dental clinics in Kuantan city of Pahang state, Malaysia (Dr Fatain’s Dental Clinic Taman Tas; Dr Fatain’s Dental Clinic Indera Mahkota 3). These radiographs were hand traced using acetate paper and 0.3 mm leaded propelling pencil on a light view box in a darkened room. The soft tissue outlines and the Rickett’s E-line (from the tip of the nose to the soft tissue chin) were drawn and the distance of the upper and lower lips to this line was measured in mm with a metal ruler. The values were compared with the Caucasian norms [upper lip to E-line: -4 mm; lower lip to E-line: -2 mm (± 2)]. The cephalometric norms of upper and lower lips to the E-line among the Malay females of Kuantan city were -1.3 mm (± 2.0) and 0.19 mm (± 1.9) respectively. This value was significantly different than the norms of the Caucasian population (p &lt; 0.001). In conclusion, the cephalometric norms of upper and lower lips to Rickett’s E-line in the Malay female population of Kuantan city were established: upper lip -1.3 mm (± 2.0) and lower lip 0.19 mm (± 1.9), which were found to be more protrusive than the Caucasian norms.

The Maxilla-Mandibular Discrepancies through Soft-Tissue References: Reliability and Validation of the Anteroposterior Measurement

This research aimed to identify a new measurement to diagnose the sagittal maxillary and mandibular difference that considers the patient's profile (soft tissue Wits appraisal: obtained by projecting points A and B on the occlusal plane and subsequently measuring the linear distance between the two points). This new measurement was compared to the conventional Wits appraisal obtained to diagnose sagittal jaw discrepancy. In total, 300 subjects (162 males, 138 females) aged between 6 and 50 years requiring orthodontic treatment were analyzed. The cephalometric tracings on the pre-treatment lateral cephalometric radiographs were obtained and the two measurements taken were the Wits appraisal and a new measurement which were both calculated and compared. The analysis of the linear correlations between the conventional Wits value and the measurement obtained on the soft-tissue were undertaken. The relevance was established at 5% (p < 0.05). The mean values were also calculated within sex and age classes, and comparisons between sexes were obtained employing the t test Student's for independent samples. Subsequently, chi-square analysis was also utilized to verify the sex distributions in the age groups considered. The results obtained suggested that these two measurements were significantly correlated with each other, with no characteristic patterns of sex or age. These data allowed an estimation of the reference values of the new measurement (-1.9 mm and 5.4 mm for patients with Class I molar relationship) showing that the former was more variable than the latter. The new measurement could allow for an accurate evaluation of the jaws sagittal discrepancy from soft tissue analysis.

Changes in the pharyngeal airway space and hyoid bone position after sagittal split ramus osteotomy in mandibular asymmetry: A retrospective cephalometric study

ObjectiveThe purpose of the present study was to compare changes in the stability of the pharyngeal airway space (PAS) and the hyoid bone position between patients with and without mandibular asymmetry. MethodsWe included 104 patients who underwent sagittal split ramus osteotomy. Patients whose menton was deviated by ≥ 4 mm from the facial median line were categorized as the asymmetry group. The patients were divided into the symmetry group (72 patients) and the asymmetry group (32 patients). The patients treated were evaluated using lateral cephalometric radiography 1 and 6 months postoperatively. ResultsFollowing orthognathic surgery, the airway space in the oropharynx and the hypopharynx significantly decreased in both the both groups (p < 0.05). The diameters of the oropharynx and hypopharynx in the asymmetry group gradually decreased after sagittal split ramus osteotomy compared with those in the symmetry group (p < 0.05). The hyoid bone was moved in an inferoposterior direction postoperatively in both groups. In the symmetry group, the hyoid bone that was moved inferiorly tended to move back toward the original position over a period of 6 months postoperatively(p < 0.05). In the asymmetry group, the hyoid bone that was moved inferiorly remained in the same position 6 months postoperatively. ConclusionThese results showed that the time required before pharyngeal airway morphology and the hyoid bone were stabilized was relatively longer in the asymmetry group.

Comparison study of the Le Fort I osteotomy using 2- and 4-plate fixation.

This study was conducted to evaluate the postsurgical stability of Le Fort I osteotomy using zygomatic buttress internal fixation alone with no piriform aperture internal fixation. Patients with maxillary retrognathia and mandibular prognathism underwent the Le Fort I osteotomy with a bilateral sagittal split ramus osteotomy. In group I, fixation was accomplished using titanium plate and screws placed at the piriform aperture and the zygomatic buttress (4 plates). In group II, fixation was accomplished using titanium plate and screws placed at the zygomatic buttress (2 plates). Lateral cephalometric radiographs were taken preoperatively (T1), immediately after surgery (T2), and at 6 months to 1 year (T3) to evaluate skeletal movement. In total, 32 patients were included in this study. None of the patients had wound infection, dehiscence, bone fragment instability, and long-term malocclusion. Regarding point A and the posterior nasal spine (PNS), vertical and horizontal relapse in groups I and II did not differ significantly. In most hospitals, the maxilla was fixed using four plates (piriform aperture and zygomatic buttress); however, within the limitations of the study, the choice of the number of plates for osteosynthesis following Le Fort I osteotomy and repositioning of the maxilla can be left to the discretion of the surgeon without putting the patients at risk for increased relapse by careful intraoperative management.