Treatment Strategy for Condyle/Ramus Deficiency Using 3D Virtual Surgery and CAD/CAM Technologies; Total Joint Replacement or Inverted-L Osteotomy.

OBJECTIVE: To introduce a guideline for selecting proper surgical modalities for correction of skeletal Class II malocclusion with moderate-to-severe vertical height deficiency (VHD) of the condyle/ramus complex (CRC) using bimaxillary surgery in conjunction with total joint replacement (TJR) or inverted-L osteotomy (ILO) assisted by 3D virtual surgical planning and CAD/CAM technologies. CASES: Four cases of severe skeletal Class II patients with moderate-to-severe VHD of CRC were presented. They underwent bimaxillary surgery using Le Fort I osteotomy in the maxilla and TJR or ILO in the mandible, with the help of virtual surgical planning (VSP) and computer-aided design/computer-aided manufacturing (CAD/CAM)-printed surgical guides and osteosynthesis plates. Guidelines are as follows: (1) if a patient has a moderate degree of VHD and the function of the temporomandibular joint (TMJ) is normal, ILO would be preferred for vertical elongation of the ramus; (2) if a patient has congenitally small condyle or severe condylar resorption, TJR would be preferred to resolve severe VHD of CRC; and (3) when a patient has a metal allergy, foreign body reaction or anatomic limitations (ie, thin cranial base cortex for fossa fixation), ILO would be a better option than TJR. RESULTS: TJR or ILO using VSP and CAD/CAM-printed surgical guides, wafers, and customized plates can provide a proper selection of the surgical plan, accurate transfer of surgical plans to actual surgical procedures, and esthetic improvement of the facial profile. CONCLUSION: This guideline based on the degree of VHD and functional aspects of CRC might help clinicians to select effective surgical modality for correction of skeletal Class II malocclusion with moderate-to-severe VHD of CRC.

Classifications of Prominent Mandibular Angle and Surgical Considerations for Mandibuloplasty.

Contouring surgery is an operation that makes a smooth, oval-shaped face by removing protruding parts of the face. In particular, mandibuloplasty is a procedure that softens the shape of the mandible and is a popular procedure among Asians with a dominant mesocephalic profile. In this study, we tried to discuss the considerations before surgery by dividing the mandibular shape into morphologic aspects in the lateral and frontal views and anatomic considerations. In the lateral view, it is essential to consider the posterior ramal height and mandibular body length of each patient. These factors are closely related to the postoperative outcomes. Consideration of the mandibular plane angle is also essential. In the frontal view, the position of the gonial angle relative to the ramal body should be considered because the position of the gonial angle can affect the difficulty of operation. Anatomic considerations include antero-posterior ramal width, bucco-lingual width of mandibular body, amount of mouth opening, and location of inferior alveolar nerve. These are important factors that determine the difficulty of the operation. In this study, classification according to the shape and shape of the mandible was presented, and considerations for each classification were discussed. Cosmetic surgery is a socio-psychologically meaningful procedure that not only improves the esthetics but also improves the mental well-being of the patients. Therefore, it will be possible to provide better medical services to patients if clinicians are fully aware of the factors that can increase the difficulty of the operation and the factors that affect the surgical outcome.

Surgical Accuracy of 3D Virtual Surgery and CAD/CAM-Assisted Orthognathic Surgery for Skeletal Class III Patients.

Orthognathic surgery is an effective surgical method to achieve functionality and facial esthetics for mandibular prognathism. If surgery is performed with a conventional method, errors may occur in the surgical preparation process and the surgical procedures, and there is a limitation in that the accuracy of surgery is determined according to the surgeon's experience and tactual sense. However, with the recent development of three-dimensional (3D) virtual planning and CAD/CAM technology, more 3D and predictable surgical planning and more accurate and time-saving surgery have become possible. The purpose of this study is to evaluate the surgical accuracy of 3D Virtual Surgery, CAD/CAM-Assisted Orthognathic surgery for Skeletal Class III Patients. The study included 18 patients who had undergone orthognathic surgery for skeletal class III malocclusion from January 2020 to December 2021. To evaluate the accuracy of the virtual planning, 3D facial cone-beam computed tomography taken immediately after surgery (T1) and virtual surgery data (Tv) were superimposed in each patient. Landmarks were set on each of the maxillary segment, mandibular distal segment, and left and right mandibular proximal segment, and the difference between T1 and Tv was compared 3D on the x , y , and z -axis. (ΔT: T1-Tv). As a result, the average distance between Tv and T1 at each landmark, all landmarks except for the posterior nasal spine of the maxillary segment showed <1 mm. In particular, the differences across the x and z -axis were very small, while the difference across the y -axis tend to be large. The comparison of the position of each segment in virtual surgery and actual surgery was as follows. It can be seen that all segments were located slightly downward, and the medial pole of the mandibular proximal segment was located posterolateral and the lateral pole was located anteromedial after the actual surgery compared with the virtual planning. It means that the proximal segment was slightly rotated, but the difference was within 1 mm, so it can be considered that the surgery was accurate. Base on this study, orthognathic surgery using 3D virtual surgery planning and CAD/CAM technologies was very accurate. By applying these cutting-edge technologies to clinical practice, it was possible not only to increase the predictability of surgery but also to improve the convenience of surgery. Therefore, it is thought that it will be important for clinicians to make continuous efforts to applicate cutting-edge technologies to be developed in the future to patient diagnosis and surgery.

The Efficacy of 3D Virtual Surgery, CAD/CAM, and 3D Printing Technology for Maxillomandibular Advancement in Obstructive Sleep Apnea Patients.

OBJECTIVE: Maxillomandibular advancement (MMA) is the most effective surgical method for treating obstructive sleep apnea, and it moves the maxillomandibular complex forward to increase the entire upper airway volume. By using 3-dimensional (D) virtual surgery, computer-aided design/computer-aided manufacturing, and 3D printing technologies, it is possible to overcome all the limitations of conventional methods. MATERIALS AND METHODS: In this study, (modified) MMA was performed by applying 3D technologies to obstructive sleep apnea patients. Virtual surgery was done as surgical plan, cutting guides, and customized plates were made by computer-aided design/computer-aided manufacturing and 3D printing technologies for surgical procedures. RESULTS: After surgery, all patients improved their appearance, quality of sleep, and sleep apnea level were dramatically improved. Through these results, it was found that there are many advantages in using 3D technologies for preparing and implementing MMA. CONCLUSIONS: It was confirmed that the accuracy and efficiency of surgery were increased by applying 3D technologies. This suggests that 3D technologies are very useful tools in surgical area.

Causes of Reoperation Consultation and Clinical Review of Actual Reoperation After Previous Orthognathic Surgery.

OBJECTIVE: To investigate the causes of reoperation consultation, and the actual percentage and procedures of reoperation after previous orthognathic surgery. METHODS: The samples consisted of 30 patients who visited our clinic for reoperation consultation from October 2015 to September 2021 (6 males and 24 females; mean age at reoperation consultation, 28.4 y). Patient's causes of reoperation consultation were divided into "esthetic dissatisfaction," "airway changes," "temporomandibular disorders," "uncomfortable occlusion," and "other complications". In terms of esthetic dissatisfaction, the more detailed esthetic problem was evaluated by the clinical chart, facial photographs, and radiographs. In patients who actually underwent reoperation, the actual percentage and procedures of reoperation were investigated. RESULTS: The most prevalent causes for reoperation consultation were "esthetic dissatisfaction" (n = 21, 70.0%), followed by "airway changes" (n = 11, 36.7%), "uncomfortable occlusion" (n = 8, 26.7%), "other complications" (n = 5, 16.7%), and "temporomandibular disorder" (n = 4, 13.3%). Less than half of patients actually underwent reoperation (n = 13, 43.3%). Actual reoperation procedures included minor revision surgery, reconstruction surgery, or complete reoperation according to the patient's need. In case of complete reoperation, more accurate and predictable results were obtained by using virtual surgical planning, customized surgical guides, titanium surgical plates made with computer-aided design and computer-aided manufacturing technique, and a 3-dimensional printing method. CONCLUSION: It is important to communicate with patients about expectations for facial esthetic improvement by orthognathic surgery for obtaining the patient's postoperative satisfaction.

The Accuracy and Stability of Intentional Change of Frontal-Ramal Inclination in Orthognathic Surgery for Facial Asymmetry Patients.

Facial asymmetry can be defined as differences in the left and right sides of the face, and most of the patients with facial asymmetry have different left and right frontal-ramal inclinations (FRIs). Restoring the symmetry of both FRIs is important in the surgery of facial asymmetry patients, but it is very difficult to achieve perfect symmetry through conventional orthognathic surgery. However, by using 3-dimensional (3D) virtual planning and CAD/CAM technolo gies, intentional change of FRIs can be possible so the symmetry can be improved. The purpose of this study is to evaluate the surgical accuracy and long-term stability of intentional change of FRIs by 3D virtual surgery, CAD/CAM-assisted orthognathic surgery for patients with facial asymmetry. The study included 20 patients who had undergone orthognathic surgery for skeletal class III malocclusion from January 2019 to December 2021. To evaluate the accuracy of surgery, 3D facial cone beam computed tomography (CBCT) taken immediately after surgery (T1) and virtual surgery data (Tv) were measured and the difference values were calculated. The evaluation of the long-term stability of intentional change of FRI was performed by measuring T1 and T2 (3D facial cone beam computed tomography images taken 6 mo after surgery) and the difference values were calculated. The difference values of FRIs in the left and right proximal segments of each patient were calculated. And then, for comparison depending on the direction of rotation, increased FRI groups (n=20, medial rotation) and decreased FRI groups (n=20, lateral rotation) were analyzed separately. As a result, all difference values at both (ΔT1-Tv) and (ΔT2-T1) were <1 degree. As a result of analyzing the entire FRI by dividing it into decreasing and increasing groups, the mean value of (ΔT1-Tv) was 0.225 degrees for the decreasing group and 0.275 degrees for the increasing group. It means that the proximal segment moved less than the movement implemented by the virtual surgery through actual surgery but it shows a very small error, which means that the overall operation almost accurately implements the virtual surgical planning. Compared with (ΔT1-Tv), the mean value of (ΔT2-T1) showed a much smaller error value, and no specific tendency was observed. This indicates that the stability after surgery is very good. Based on this study, using 3D virtual surgery planning and CAD/CAM technologies for treating patients with facial asymmetry was very useful, and surgery could be performed accurately and predictably. In particular, left-right symmetry was almost perfectly achieved through virtual simulation and could be implemented through actual surgery. Therefore, it can be said that the use of these 3D technologies is recommended for the surgical approach of facial asymmetry.

Restoration of Facial Bone Defect using Patient-Specific Implant.

ABSTRACT: Facial bone defects can be caused by various causes, such as congenital deformities, iatrogenic results, and trauma. If the size of the bone defect is small, it can be repaired using premanufactured products, but it is not accurate and impossible to restore large bony defect. In the effort to overcome these limitations of premanufac-tured implants, the authors use patient-specific implant (PSI) via computer-aided design/computer-aided manufacturing and 3D printing technologies for facial bone restoration surgery. In this study, the authors use polyetherketoneketone and titanium alloy for implant material among various capable of 3D printing. As a result of analyzing the patients who underwent surgery in this study, PSIs were made in 57 sites for 29 patients. The most common reason for surgery was to improve the patient's esthetics (14 cases), followed by the improvement of iatrogenic complications and postoperative dissatisfaction (11 cases). Restoration of the congenital bony defect was the least (4 cases). Postoperative complications were occurred in 5 patients (screw loosening in 1 case, postoperative dissatisfaction in 3 cases, and postoperative infection in 1 case). There is no case of rejection after implant insertion, because the authors use polyetherketoneketone and titanium alloy for implant material which are good biocompatibility. By using PSIs via 3D technologies, the authors can overcome the limitations of premanufactured products. Moreover, the authors could get better results. So these cutting edge technologies can improve our surgical procedures and predictability.

Correction of Midface Deficiency in Patient With Crouzon Syndrome by Orthognathic Surgery and Patient Specific Facial Implant: Case Report.

ABSTRACT: Crouzon syndrome, also known as craniofacial dysostosis, is an autosomal dominant inherited disease characterized by early cranial fusion and consequential craniofacial malformations. In patients with Crouzon syndrome, the growth of the midface is affected due to early fusion of the cranial base, which results in exophthalmos, ocular ptosis, midface deficiency, and maxillary retrognathism. Frontofacial advancement using Le Fort III osteotomy is the conventional method for treating patients with Crouzon syndrome. However, this procedure has drawbacks such as extensive operation field and high possibility of serious complications (eg, meningitis). For patients with mild symptoms, facial esthetics and proper occlusion can be promoted through conventional orthognathic surgery, but midface deficiency cannot be completely resolved. Thus, in this case report, midface augmentation was performed for a patient with Crouzon syndrome by undergoing conventional orthognathic surgery, along with patient-specific implants made using a 3D virtual technique. Implants were 3D printed using polyetherketoneketone and simultaneously implanted during the orthognathic surgery. After the surgery, not only were the patient's occlusion and facial esthetics improved, but also exophthalmos and ocular ptosis were reduced by the midfacial augmentation effect of patient-specific implants placed in the midface. Since the implants were made exactly as what surgeons have intended through computer-aided design (CAD)/computer-aided manufacturing (CAM) and 3D printing techniques, problems such as under-/over-correction were avoided. In addition, the possibility of implant malpositioning was minimized using surgical stents as implants were passively fitted on the patient's bone surface. This case verified that the application of 3D technology to the field of oral and maxillofacial surgery can reduce the invasiveness of surgery and improve the accuracy of the operation. Therefore, by using cutting-edge technologies, the field of oral and maxillofacial surgery is expected to be developed further in the near future.

Maxillary Total Elongation Surgery using 3D Virtual Surgery, CAD/CAM and 3D Printing Technology: Surgical Convenience and Accuracy.

After Le Fort I osteotomy was first performed by von Langernbeck in 1859, there has been many improvements since. Research on and development of Le Fort I osteotomy procedure has shown downward movement of the maxilla to exhibit lowest stability and accuracy. However, maxillary downgraft movement is necessary in orthognathic patients with insufficient vertical length of the maxilla, but fixation of the maxilla after elongation is often very inaccurate. In this study, the authors utilized 3D virtual surgery, CAD/CAM-assisted 3D printing technology to overcome such limitations of maxillary total elongation. In addition, accuracy at 7 different landmarks from superimposition of virtual simulation data and postoperative Cone-beam computed tomography (CBCT) data were measured. Although posterior maxilla exhibited bigger range of errors, an error of <1 mm was measured at all 7 landmarks. Operation time was greatly shortened with cutting guides and customized plates. Although this study is a single-case study, this study shows increased accuracy and efficacy from application of 3D virtual surgery, CAD/CAM, and 3D printing technology.

MSM promotes human periodontal ligament stem cells differentiation to osteoblast and bone regeneration.

Periodontal disease is the most common chronic disease of the oral and maxillofacial region, causing alveolar bone loss and ultimate loss of tooth. The purpose of treatment of periodontal disease is to promote the regeneration of periodontal tissue, including alveolar bone, and implantation of fixtures to replace the missing tooth as a result of advanced periodontal disease also requires alveolar bone regeneration. Methylsulfonylmethane (MSM) is a sulfur compound with well-known anti-inflammatory effects but its effects on bone regeneration are unknown. In this study, we investigated the effects of MSM on osteogenic differentiation of human PDLSCs (hPDLSCs) in vitro and in vivo. Our results demonstrate that MSM not only promotes the proliferation but also promotes osteogenic differentiation of hPDLSCs. MSM increased the expression levels of osteogenic specific markers that ALP, OPN, OCN, Runx2, and OSX. Smad2/3 signaling pathway was reinforced by MSM. Runx2, which downstream of Smad pathway, was expressed in accordance. Consistent with in vitro results, in vivo calvarial defect model and transplantation model revealed that MSM induces hPDLSCs to differentiate into osteoblast, which express ALP, OPN and OCN highly and enhance bone formation. These results suggest that MSM promotes osteogenic differentiation and bone formation of hPDLSCs, and Smad2/3 / Runx2 / OSX / OPN may play critical roles in the MSM-induced osteogenic differentiation. Thus, MSM combined with hPDLSCs may be a good candidate for future clinical applications in alveolar bone regeneration and can be used for graft material in reconstructive dentistry.

Treatment of severe pain in a patient with complex regional pain syndrome undergoing dental treatment under general anesthesia: A case report.

Complex regional pain syndrome (CRPS) is rare, characterized by pain from diverse causes, and presents as extreme pain even with minor irritation. General anesthesia may be required for dental treatment because the pain may not be controlled with local anesthesia. However, treatment under general anesthesia is also challenging. A 38-year-old woman with CRPS arrived for outpatient dental treatment under general anesthesia. At the fourth general anesthesia induction, she experienced severe pain resulting from her right toe touching the dental chair. Anesthesia was induced to calm her and continue the treatment. After 55 minutes of general anesthesia, the patient still complained of extreme toe pain. Subsequently, two administrations for intravenous sedation were performed, and discharge was possible in the recovery room approximately 5 h after the pain onset. The pain was not located at the dental treatment site. Although the major factor causing pain relief was unknown, ketamine may have played a role.

Microwave-assisted pretreatment of cellulose in ionic liquid for accelerated enzymatic hydrolysis.

For increasing cellulose accessibility to the enzymatic attack, the pretreatment is a necessary step to alter some structural characteristics of cellulosic materials. As a new pretreatment method, microwave irradiation on cellulose dissolution pretreatment with ionic liquids (ILs) was investigated in this study. Microwave irradiation not only enhanced the solubility of cellulose in ILs but also significantly decreased the degree of polymerization of regenerated cellulose after IL dissolution pretreatment, resulting in significant improvement of cellulose hydrolysis. The rate of enzymatic hydrolysis of cotton cellulose was increased by at least 12-fold after IL dissolution pretreatment at 110 °C and by 50-fold after IL dissolution pretreatment with microwave irradiation. Our results demonstrate that cellulose pretreatment with ILs and microwave irradiation is a potential alternative method for the pretreatment of cellulosic materials.