Pusan National University Dental Hospital Research Articles

Retrospective analysis on prognosis of oral cancer patients according to surgical approaches for effective cancer ablation: swing approach versus visor approach

BackgroundFor the surgical treatment of oral cancer, it is sometimes necessary to expand intraoral access within the oral cavity. The “swing approach” that involves lip splitting of the mandible and temporary mandibular osteotomy and the “visor approach” that does not split the lower lip and mandible are mainly used. This study analyzed postoperative outcomes such as complications, recurrence rate, and survival rate by these two approaches. The goal of this study is to evaluate the surgical outcomes of patients using these two approaches, to propose effective perioperative management for oral cancer surgery, and to compare the prognosis of oral cancer patients.Materials and methodsFrom 2005 to 2020, 29 patients who underwent surgery at the Department of Oral and Maxillofacial Surgery of Pusan National University Dental Hospital for oral cancer lesions occurred in the mandible, floor of mouth, and tongue were selected for the study. Based on the surgical approach used, a chart review was conducted on various prognostic clinical factors such as the patients’ sex and age, primary site, TNM stage, histopathologic grade, recurrence and metastasis, postoperative survival rate, adjuvant chemo-radiation therapy, satisfaction with aesthetics/function/swallowing, length of hospital stay, tracheostomy and its duration, and neck dissection and its type. Statistical analysis was conducted using SPSS 25.0 (SPSS Inc., Chicago, IL) through Fisher’s exact t-test.ResultThere was no statistically significant difference between two groups in terms of clinical and pathological findings, such as survival rate, the need for adjuvant therapies, and the local recurrence rate. Although better outcomes were observed in terms of function, aesthetics, and postoperative complications in the group with visor approach, there was still no statistically significant difference between two groups. However, the duration of hospital stay was shorter in the visor approach group.ConclusionThere was no statistically significant difference in clinical prognostic factors between the swing approach and the visor approach. Therefore, when choosing between the two approaches for the ablation of oral cancer, it is considered to select the surgical priority approach that can be easy access based on the size and location of the lesion. The visor approach had advantages of aesthetics and healing period.

Classification of presence of missing teeth in each quadrant using deep learning artificial intelligence on panoramic radiographs of pediatric patients.

Early tooth loss in pediatric patients can lead to various complications, making quick and accurate diagnosis essential. This study aimed to develop a novel deep learning model for classification of missing teeth on panoramic radiographs in pediatric patients and to assess the accuracy. The study included patients aged 8-16 years who visited the Pusan National University Dental Hospital and underwent panoramic radiography. A total of 806 panoramic radiographs were retrospectively analyzed to determine the presence or absence of missing teeth for each tooth number. Moreover, each panoramic radiograph was divided into four quadrants, each of a smaller size, containing both primary and permanent teeth, generating 3224 data. Quadrants with missing teeth (n = 1457) were set as the experimental group, and quadrants without missing teeth (n = 1767) were set as the control group. The data were split into training and validation sets in a 4:1 ratio, and a 5-fold cross-validation was conducted. A gradient-weighted class activation map was used to visualize the deep learning model. The average values of sensitivity, specificity, accuracy, precision, recall and F1-score of this deep learning model were 0.635, 0.814, 0.738, 0.730, 0.732 and 0.731, respectively. In the experimental group, the accuracy was the highest for missing canines and premolars, and the lowest for molars. The deep learning model exhibited a moderate to good distinguishing power with a classification performance of 0.730. This deep learning model and the newly defined small sized region of interest proved adequate for classifying the presence of missing teeth.

Clinical Analysis of Patients who Underwent Reoperation After Orthognathic Surgery: A 14-Year Retrospective Study.

The purpose of this study was to analyze the patients clinically who underwent reoperation after certain Orthognathic procedures, and to assess the reoperation rate. Furthermore, the authors also evaluated the incidence of intraoperative and postoperative complications that led to the need for reoperation. Total 526 patients were selected who underwent Orthognathic surgery between July 2008 and February 2022 at the Department of Oral and Maxillofacial Surgery in Pusan National University Dental Hospital by single surgeon. All the patients information were extracted from electronic database of our university. Demographic, radiologic, intraoperative, and postoperative data were recorded and compiled. Out of 526 patients, 265 (50.3%) were males and 261 (49.6%) were females. The total number of patients who showed complication is 89 (16.9%) and the patients who underwent reoperation are 17 (3.2%). The common complications that occurred were postoperative sensory disturbance (31; 5.8%), unwanted fractures (17; 3.2%), intraoperative nerve injury (11; 2%), wound dehiscence (11; 2%), infection (10; 1.9%), tooth injury (2; 0.3%), and others (18; 3.4%). The serious complications that led to reoperation include severe bleeding (6; 1.1%), unesthetic results (5; 0.9%), non-union of maxilla (4; 0.7%), and failed osteosynthesis (2; 0.3%). After 2018, all the orthognathic surgeries were performed with the help of virtual surgical planning. After application of virtual surgical planning, the number of patients with complications statistically decreased. The present study showed that the reoperation rate after orthognathic surgery was low, this rate was more decreased after applying 3-dimensional virtual surgery and 3-dimensional printed plate, especially in unesthetic cases.

Prevalence and Patterns of Congenitally Missing Teeth among Pediatric Patients Aged 8 - 16 in Pusan National University Dental Hospital

The purpose of this study was to investigate the prevalence and patterns of congenitally missing teeth in permanent teeth excluding third molars, in patients aged 8 to 16 years who visited Pusan National University Dental Hospital from January 2010 to February 2021. This retrospective study evaluated tooth agenesis and the pattern of missing teeth represented by the tooth agenesis code by reviewing panoramic radiographs and electronic medical records of 11,759 patients, including 5,548 females and 6,211 males. The prevalence of congenitally missing teeth was 10.74% (females 11.95%, males 9.66%, <i>p</i> < 0.0001). Patients with tooth agenesis had an average of 2.22 missing teeth, and congenitally missing teeth occurred more frequently in the mandible (8.39%) than in the maxilla (4.52%, <i>p</i> < 0.0001). The mandibular second premolar (58.19%) was the most frequently missing tooth. The second premolar was the most frequently missing tooth in all quadrants (30.10%, 31.67%, 43.14%, and 35.59%) when a single tooth was absent, while the first and second premolars were the most commonly absent teeth (11.69%, 11.47%, 5.94%, and 5.24%) when two or more teeth were missing. In the relationship between maxillarymandibular antagonistic quadrants and full mouth, the 1st to 4th place of the missing patterns were all involved with the 1st and 2nd premolars. This study can be clinically helpful in establishing a treatment plan for patients with missing teeth. In addition, it can be used as basic data for molecular biological research to find out the relationship between tooth agenesis and specific genes.

Utilization of an Artificial Intelligence Program Using the Greulich-Pyle Method to Evaluate Bone Age in the Skeletal Maturation Stage

The purpose of this study was to measure bone age using an artificial intelligence program based on the Greulich-Pyle (GP) method to find out the bone age corresponding to each stage of cervical vertebral maturation (CVM) and the middle phalanx of the third finger (MP3). This study was conducted on 3,118 patients who visited pediatric dentistry at Kyung Hee University Dental Hospital and Pusan National University Dental Hospital from 2013 to 2021. The CVM stage was divided into 5 stages according to the classification by Baccetti, and the MP3 stage was divided into 5 stages according to the methods of Hägg and Taranger. Based on the GP method, bone age was evaluated using an artificial intelligence program. The pubertal growth spurt in the CVM stage was CVM II and III. The mean bone age in CVM II was 11.00 ± 1.81 years for males and 10.00 ± 1.49 years for females, and in CVM III, 13.00 ± 1.46 years for males and 12.00 ± 1.44 years for females (<i>p</i> < 0.0001). The pubertal growth spurt in the MP3 stage was MP3 - G stage. The bone age at the MP3 - G stage was 13.14 ± 1.07 years for males and 11.40 ± 1.09 years for females (<i>p</i> < 0.0001). Bone age evaluation using artificial intelligence is worth using in clinical practice, and it is expected that a faster and more accurate diagnosis will be possible.

The Distribution of Pediatric Patients According to Accessibility to Dental Facilities in Pusan National University Dental Hospital

The purpose of this study was to analyze the accessibility to dental facilities and the differences in chief complaints of new patients who visited Pusan National University Dental Hospital. We collected information from electronic medical records for 1,820 new patients. The accessibility was analyzed by measuring the distance from the patient’s house to the dental facilities. The distance was categorized into 10 km sections, and the presence or absence of a local pediatric dental clinic within 10 km of the patient’s house was also categorized. As the distance between the house and Pusan National University Dental Hospital increased, the proportion of patients who visited for dental caries decreased, and orthodontic treatment increased. Dental caries accounts for 27.9% of less than 10 km and 20.5% over 30 km. Orthodontic treatment accounts for 25.4% within 10 km and 27.3% more than 30 km away. The presence or absence of a local pediatric dental clinic within 10 km did not significantly affect the distribution of chief complaints. This study can be used as basic research data to establish effective treatment measures that can improve the physical and geographical accessibility of patients visiting pediatric dentistry.

Age Estimation through Molar Attrition in Korean Population

Methods available for estimating the age of a living body are somewhat limited when there is shortage of teeth. This study aimed to determine whether the average stage of attrition (ASA) method published in 1995 by Li and Ji is practical among Koreans in their 50s and 60s. A total of 173 cases using 265 molars from 92 patients in their 50s and 60s who underwent age assessment at the Department of Oral Medicine at Pusan National University Dental Hospital from 2012 to 2022 were analyzed through clinical photographs and diagnostic casts. ASA method was used to determine the average attrition of cusps and calculate the estimated age. There was a moderate correlation between the average attrition of molars and the patients’ actual age. In patients in their 50s and 60s, the error range between the estimated age and the actual age was less than 10 years in 139 of 173 cases (74.56%), and age was underestimated in 147 cases (84.98%). The tendency for age to be underestimated was higher in women than in men. Regression analysis using both the first and second molars showed that the influence of the first molar was greater than that of the second molar. Although the correlation is not very high, considering the limitations of age estimation in the living body, this method may be useful if coupled with another method such as dental radiograph analysis when there is an absolute shortage of available teeth.

Three-Dimensional Analysis of Bone Volume Change at Donor Sites in Mandibular Body Bone Block Grafts by a Computer-Assisted Automatic Registration Method: A Retrospective Study

This study aimed to evaluate the bone volume change at donor sites in patients who received mandibular body bone block grafts using intensity-based automatic image registration. A retrospective study was conducted with 32 patients who received mandibular bone block grafts between 2017 and 2019 at the Pusan National University Dental Hospital. Cone-beam computed tomography (CBCT) images were obtained before surgery (T0), 1 day after surgery (T1), and 4 months after surgery (T2). Scattered artefacts were removed by manual segmentation. The T0 image was used as the reference image for registration of T1 and T2 images using intensity-based registration. A total of 32 donor sites were analyzed three-dimensionally. The volume and pixel value of the bones were measured and analyzed. The mean regenerated bone volume rate on follow-up images (T2) was 34.87% ± 17.11%. However, no statistically significant differences of regenerated bone volume were noted among the four areas of the donor site (upper anterior, upper posterior, lower anterior, and lower posterior). The mean pixel value rate of the follow-up images (T2) was 78.99% ± 16.9% compared with that of T1, which was statistically significant (p < 0.05). Intensity-based registration with histogram matching showed that newly generated bone is generally qualitatively and quantitatively poorer than the original bone, thus revealing the feasibility of pixel value to evaluate bone quality in CBCT images. Considering the bone mass recovered in this study, 4 months may not be sufficient for a second harvesting, and a longer period of follow-up is required.

Management of Mandibular Subcondylar Fracture Through an Intraoral Approach Using a Trans-Buccal Trocar With Ramus Buccal Decortication

The aim of this study was to review retrospectively the functional recoveries of subcondylar fracture patients that underwent open reduction surgery using an extraoral approach or an intraoral approach using a trans-buccal trocar and involving ramus buccal decortication. Of 47 patients with mandibular condyle fracture who visited Pusan National University Dental Hospital Department of Oral and Maxillofacial Surgery between May 2015 and November 2020, 38 patients underwent open reduction and were classified according to the surgical method used. Preauricular, submandibular, and retro-mandibular approaches were all classified as extraoral approaches condyle fractures were classified as described by Spiessl and Schroll (1972). Distances between bone fragments on panorama radiographs before and after surgery were measured. Thirty-eight patients were included in this study, 9 patients received subcondylar fracture surgery. Open reduction surgery using an extraoral approach had a greater mean operation time than the intraoral approach using a trocar. Of the 17 patients treated with an intraoral approach, the average distance between bone fragments right after surgery was 1.27 ± 1.41 mm, which was significantly greater than that of the extraoral approach (0.72 ± 0.35 mm). Favorable results can be obtained by mandibular condylar fracture surgery through an intraoral approach using a trans-buccal trocar with ramus buccal decortication. This technique minimizes scarring, secures accessibility using a trocar, and sufficiently secures the field of view through buccal cortical bone reduction.

Complications According to the Handling of the Pterygoid Plate During Bimaxillary Surgery.

During bimaxillary surgery, manipulation of the pterygoid plate is required to facilitate movement of the maxilla. This study examined the complications that occurred after handling the pterygoid plate during a Le Fort I osteotomy. This study compared and analyzed complications according to the pterygoid plate handling method in 80 patients who underwent bimaxillary surgery at Pusan National University Dental Hospital from December 2015 to July 2020. The pterygoid plate was fractured or removed intentionally only if it interfered with the maxilla. Otherwise, it was not treated. The complications during surgery and the follow-up period were investigated. Fourteen patients experienced complications, of which excessive bleeding, hearing problems, and nonunion were encountered in 10, 2, and 2 patients, respectively. Of the 10 patients with excessive bleeding patients, the pterygoid plate was manipulated in 8 patients, which was controlled during surgery. Two patients complained of hearing loss with ear congestion immediately after surgery; both patients improved spontaneously within 1 month. Two nonunion patients underwent plate refixation at least 6 months postoperatively, and normal healing was achieved afterward. Fracture and removal of the pterygoid plate during orthognathic surgery did not significantly affect the occurrence of complications during and after surgery.

Retrospective analysis of the effects of non-communicable diseases on periodontitis treatment outcomes.

PurposeWe retrospectively analysed patients’ dental and periodontal status according to the presence of non-communicable diseases (NCDs) and the effects of NCDs on periodontal treatment outcomes. Factors influencing disease recurrence were investigated using decision tree analysis.MethodsWe analysed the records of patients who visited the Department of Periodontology, Pusan National University Dental Hospital from June 2014 to October 2019. As baseline subjects, 1,362 patients with periodontitis and who underwent full-mouth periodontal examinations before periodontal treatment were selected. Among them, 321 patients who underwent periodontal examinations after the completion of periodontal treatment and 143 who continued to participate in regular maintenance were followed-up.ResultsForty-three percent of patients had a NCD. Patients without NCDs had more residual teeth and lower sum of the number of total decayed, missing, filled teeths (DMFT) scores. There was no difference in periodontal status according to NCD status. Patients with a NCD showed significant changes in the plaque index after periodontal treatment. The decision tree model analysis demonstrated that osteoporosis affected the recurrence of periodontitis.ConclusionsThe number of residual teeth and DMFT index differed according to the presence of NCDs. Patients with osteoporosis require particular attention to prevent periodontitis recurrence.

Correlation Between Sports-Related Maxillofacial Injuries and Head Injuries: A Five-Year Retrospective Study.

As sports have become more diverse and demanding, the number of patients with a maxillofacial injury accompanied by a cranial injury or neurological symptoms has increased. This study examined the correlation between sports-related maxillofacial injuries and head injuries. Among the patients who visited the emergency department of Pusan National University Dental Hospital due to a maxillofacial injury from sporting activities between 2014 and 2018, those who additionally had head injuries were retrospectively examined. Sporting activities were classified according to the American Academy of Pediatrics classification, and severity of injuries was determined using the Facial Injury Severity Scale (FISS). Patients whose medical records showed neurological symptoms and who underwent brain computed tomography for concomitant head injury were selected. The association between each of these variables, including age and gender, was statistically analyzed. A total of 95 patients were included in this study, most of whom were male teenagers, and cycling was the most common cause of injuries. The meanFISS score was 0.79. Brain computed tomography was conducted for 91 patients, and 28 patients reported neurological symptoms. Only 11 patients underwent advanced evaluation in the neurology or neurosurgery department. Most patients were diagnosed with contusion and concussion and were monitored without any treatment. Higher FISS values did not reflect the severity of maxillofacial and head injury. In this study, there were some patients with cranial fracture and cerebral hemorrhage with mild neurosurgical symptoms of facial trauma. Although the incidence of head trauma is not high, the necessity of wearing protective equipment cannot be overemphasized because severe trauma is permanent. Neurological signs and symptoms of patients with maxillofacial trauma should not be overlooked and require a thorough evaluation.

Postoperative Stability of Patients Undergoing Orthognathic Surgery with Orthodontic Treatment Using Clear Aligners: A Preliminary Study

Backgrond: Until now, there have been many studies on the postoperative stability of orthognathic patients treated with traditional fixed orthodontic appliances. Recently, the use of clear aligners as orthodontic appliances has increased in orthodontic treatment for aesthetic and patient convenience. The aim of this preliminary study was to investigate the stability and characteristics of patients undergoing orthognathic surgery using clear aligners. Patients and Methods: This study was performed on patients who underwent orthognathic surgery by one surgeon at Pusan National University Dental Hospital from April 2017 to August 2021. A comparative study was conducted on five patients treated with clear aligners during orthodontic treatment and ten patients treated with traditional fixed appliances as a control group. Postoperative skeletal changes and recurrence were evaluated by cone beam computed tomography and lateral cephalometric radiographs taken two days postoperatively and six months postoperatively. Several measurement variables were used to confirm the presence or absence of recurrence, preoperative and postoperative orthodontic treatment period, and the number of extracted teeth. Results: Postoperative stability for six months after surgery was not significantly different between the clear aligner group and the traditional fixed appliance group. The preoperative orthodontic treatment period was also shorter in the clear aligner group, and the number of extracted premolar teeth and impacted teeth were also fewer in the clear aligner group, but there was no significant difference. Conclusions: Orthodontic treatment using clear aligners continues to develop, and it is believed that there is no limit to what can be accomplished during orthodontic surgery accompanied by clear aligners.

Skeletal Stability of Two-Jaw Surgery Without Bone Grafting in Patients With Cleft Lip and Palate.

The purpose of this study was to evaluate the postoperative skeletal stability of orthognathic surgery performed without a bone graft in cleft lip and palate patients. Nineteen cleft lip and palate patients that underwent orthognathic surgery from July 2008 to August 2019 at the Department of Oral and Maxillofacial Surgery of Pusan National University Dental Hospital were selected. None of these patients underwent bone grafting during orthognathic surgery. Lateral cephalograms were taken 1 month before surgery (T0), immediately after surgery (T1), and 6 months after surgery (T2). Lateral cephalograms were analyzed using the V-Ceph program. The analysis was performed using SPSS for Windows version 26.0. The analysis was conducted by repeated-measures analysis of variance. A total of 19 patients were included in this retrospective study (9 males/10 females of overall mean age 22 ± 4.89 years). Mean maxillary depth values at the 3-time points were 85.37° ± 2.62° (T0), 90.13° ± 2.77° (T1), and 89.29° ± 2.91° (T2). Mean McNamara-N Perpend values were -5.52 ± 3.19 mm (T0), 0.09 ± 3.10 mm (T1), and -0.83 ± 3.14 mm (T2). Mean sella nasion point A (SNA) values were 75.42° ± 2.98° (T0), 79.19° ± 2.94° (T1), and 78.45° ± 2.84° (T2). Mean relapse rates were maxillary depth 20.15%, McNamara-N Perpend 17.95%, and SNA 18.74%. Mean horizontal advancement was 5.61 ± 2.32 mm based on McNamara vertical to A point, mean horizontal relapse was -0.92 ± 0.56 mm, and the mean horizontal relapse rate was 17.95%. Favorable skeletal stability can be obtained without bone graft when the amount of maxillary advancement is less than 6 mm in cleft patients.

Comparison of Deep Learning Models for Cervical Vertebral Maturation Stage Classification on Lateral Cephalometric Radiographs.

The purpose of this study is to evaluate and compare the performance of six state-of-the-art convolutional neural network (CNN)-based deep learning models for cervical vertebral maturation (CVM) on lateral cephalometric radiographs, and implement visualization of CVM classification for each model using gradient-weighted class activation map (Grad-CAM) technology. A total of 600 lateral cephalometric radiographs obtained from patients aged 6–19 years between 2013 and 2020 in Pusan National University Dental Hospital were used in this study. ResNet-18, MobileNet-v2, ResNet-50, ResNet-101, Inception-v3, and Inception-ResNet-v2 were tested to determine the optimal pre-trained network architecture. Multi-class classification metrics, accuracy, recall, precision, F1-score, and area under the curve (AUC) values from the receiver operating characteristic (ROC) curve were used to evaluate the performance of the models. All deep learning models demonstrated more than 90% accuracy, with Inception-ResNet-v2 performing the best, relatively. In addition, visualizing each deep learning model using Grad-CAM led to a primary focus on the cervical vertebrae and surrounding structures. The use of these deep learning models in clinical practice will facilitate dental practitioners in making accurate diagnoses and treatment plans.

Evaluation of Patients with Sensory Disturbance after Dental Treatment

The Korean Dental Association recommends a disability rate (DR) of 1%-3% in the judgment of physical disability owing to sensory disturbance (SD) after dental treatment; however, criteria for deciding the exact percentage have not been suggested. Therefore, this study aims to provide practical criteria in the application of forensic physical disability evaluation by comparing the results of SD using the current perception threshold (CPT) test. A total of 324 patients with SD who visited the Department of Oral Medicine at Pusan National University Dental Hospital between January 2013 and August 2020, underwent the test. The eight stages, as a result of the CPT value, were reorganized as follows: profound sensory loss, very severe and severe as “severe group”, advanced and moderate as “moderate group”, mild and very mild as “mild group”, and normal as “normal group” The analysis of variance (ANOVA) test was used to calculate the statistical difference in the CPT values at 2000 Hz, 250 Hz, and 5 Hz among the four groups. There were significant statistical differences in the average values of CPT among the four groups (P<0.001). Additionally, a significant statistical difference in the CPT value between the affected and non-affected sides of the patients was observed among the four groups (P<0.001). Therefore, based on the results of this study, the rationale for applying DR from 1%-3% was in accordance with the severity of the mandibular nerve injury. Key Words: Iatrogenic nerve injury · Dental treatment · Sensory disturbance

Sports-Related Oral and Maxillofacial Injuries: A 5-Year Retrospective Study, Pusan National University Dental Hospital

The incidence of sports trauma is gradually increasing, and its importance is therefore also increasing. The present study was conducted to analyze the types, proportions, and tendencies of sports trauma associated with the oral and maxillofacial regions. Patients who visited the Emergency Department of Pusan National University Dental Hospital between 2014 and 2018 for more than 5years were surveyed through retrospective epidemiologic investigations. Type of sports was classified according to American Academy of Pediatrics classification. For statistical analysis, age and gender distribution, cause of trauma, and annual trends data were collected. Of the 517 patients, most of the patients were teenagers (27.9%), followed by those younger than 10years (23.2%) (χ2= 22.897; P=.002), and noncontact sports, which is cycling, was the most common (43.5%) cause for trauma in both adult and children groups (χ2= 91.824; P<.001). The most common sports associated with contact sports, limited-contact sports, and noncontact sports were football (47.7%), baseball (50.0%), and cycling (74.8%), respectively. The causes for trauma injury were as follows: contact sports, other person's body (53.4%); limited-contact sports, other objects (60.9%); and noncontact sports, slip down (77.4%) (χ2= 298.901; P<.001). The prevalence and incidence of sports injuries increase every year, and the proportion of injured patients in May was the highest (χ2= 52.360; P=.181). The high percentage of traumatic sports demonstrated statistically significant trends (χ2=43.073; P=.002). Kickboard injuries showed a rapid increase recently (P for linear trend=.045), whereas other sports showed no significant trends. Considering the increasing incidence of sports-related injuries, oral and maxillofacial surgeons should be more concerned with maxillofacial trauma during sports.

Automatic three-dimensional analysis of bone volume and quality change after maxillary sinus augmentation.

Maxillary sinus augmentation is a widely used surgical procedure to increase the bone volume before implant placement. In order to predict the stability of the implant, analysis of the change in bone volume and quality after a sinus graft procedure is necessary. The purpose of this study was to analyze the change in volume and quality of bone graft material after maxillary sinus augmentation using cone beam computed tomography (CBCT). Maxillary sinus lift procedures using bovine bone materials (Bio-Oss, Geistrich, Swiss) without immediate implantation were performed at the Pusan National University Dental Hospital in 22 patients, from 2014 to 2017. CBCT images were captured before surgery (T1), a day after surgery (T2), and after 4 to 7 months at follow-up (T3). The T2 and T3 images were registered to the T1 image using histogram matching and intensity-based registration. A total of 30 sinuses were analyzed three-dimensionally (3-D), using self-made software MATLAB 2018a (MathWorks, Natick, Massachusetts). The volume and structural indices of the bone graft material were measured and analyzed. The average volume of graft material showed a decrease, while the average gray value showed an increase during the follow-up period, but these changes were not statistically significant. The structural indices of the graft material after histogram matching showed a significant difference in homogeneity, connectivity, thickness, and roughness at the postoperative follow-up. The volume and gray value showed no statistically significant changes after the maxillary sinus lift procedures. The results of this study show that structural analysis using histogram matching can be used as a promising tool to analyze the quality of graft materials.

Comparison of time and cost between conventional surgical planning and virtual surgical planning in orthognathic surgery in Korea

BackgroundThe purpose of this study was to measure the time of the conventional surgical planning (CSP) and virtual surgical planning (VSP) in orthognathic surgery and to compare them in terms of cost.Material and methodThis is a retrospective study of the patients who underwent orthognathic surgery at the Pusan National University Dental Hospital from December 2017 to August 2018. All the patients were analyzed through both CSP and VSP, and all the surgical stents were fabricated through manual and three-dimensional (3D) printing. The predictor variables were the planning method (CSP vs. VSP) and the surgery type (group I: Le Fort I osteotomy + bilateral sagittal split osteotomy [LFI+BSSO] or group II: only bilateral sagittal split osteotomy [BSSO]), and the outcomes were the time and cost. The results were analyzed using the paired t test.ResultsThirty patients (12 females, 18 males) met the inclusion criteria, and 17 patients were excluded from the study due to missing or incomplete data. There were 20 group I patients (LFI+BSSO regardless of genioplasty) and 10 group II patients (BSSO regardless of genioplasty). The average time of CSP for group I was 385 ± 7.8 min, and that for group II was 195 ± 8.33 min. The time reduction rate of VSP compared with CSP was 62.8% in group I and 41.5% in group II. On the other hand, there was no statistically significant cost reduction.ConclusionsThe time investment in VSP in this study was significantly smaller than that in CSP, and the difference was greater in group I than in group II.

Complications Following Orthognathic Surgery for Patients With Cleft Lip/Palate.

Cleft lip/palate is a facial anomaly caused by an abnormal developmental process. It is also the most common congenital anomaly. Orthognathic surgery is required in 25% of patients with cleft lip and palate for the correction of dentofacial deformity. There are various complications that can occur after orthognathic surgery. Complications that can occur during surgery include bleeding, improper fracture, and injuries to the inferior alveolar nerve (IAN) and lingual nerve. Meanwhile, postoperative complications include hemorrhage, edema, pain, infection, and delayed union or nonunion. This study retrospectively examines the complications that occurred after the orthognathic surgery in cleft lip/palate patients at Pusan National University Dental Hospital. From June 1, 2008 to July 31, 2017, we selected 17 patients who underwent orthognathic surgery for cleft lip/palate at the Department of Oral and Maxillofacial Surgery, Pusan National University Dental Hospital. The patients were treated at different hospitals for all operations related to cleft lip/palate. Intraoperative complications include hemorrhage, inadequate fracture, injury to the IAN and lingual nerve, root damage, and fistula. The patients who were evaluated included 2 patients with inadequate fracture, 3 patients with injury to the IAN, and 1 patient with fistula. Postoperative complications (e.g., as damage of the inferior alveolar nerve and velopharyngeal insufficiency) may occur, and all patients recovered during the follow-up period of 6 months or more after the surgery. The relapse rates were A-N per 14.0%, Pog-N per 15.1%, SNA 24.4%, and SNB 4.6%. There was no statistically significant difference in relapse rate. Complications that may occur after the orthognathic surgery in the patients with cleft lip/palate are similar to those without cleft lip/palate.