Segmental Osteotomy Research Articles

Anterior Maxillary Osteotomy Distraction Osteogenesis (Amodo) in the Treatment of Maxillary Hypoplasia in Unilateral Cleft Lip and Palate-A Case Report

Distraction osteogenesis defines a technique of bone generation by distraction of native bony segments. The technique offers a promising treatment alternative for patients with maxillary or midfacial hypolasia. In this case report, the various steps in the treatment of an 18 year old boy with premaxillary hypoplasia and anterior crossbite are described. Patient was treated with a distraction osteogenesis technique and premaxillary advancement was performed using individual tooth - borne distraction device. The surgical procedure involved an anterior segmental maxillary osteotomy respecting the palatal periosteum. Distractor was cemented in the mouth after the surgical procedures. The patient was observed during a seven day latency period after which the device was activated 0.4mm every 12 hours. The anterior crossbite was eliminated and the occlusal correction and settling was achieved with fixed orthodontic appliances.

Unilateral condylar hyperplasia treated with simultaneous 2-jaw orthognathic surgery and posterior segmental osteotomy.

A 25-year-old woman presented with left condylar hyperplasia, canting-type facial asymmetry, mandibular prognathism, and arch width discrepancy. Bone scintigraphy confirmed the inactive status of the condyle, and the temporomandibular joint functioned within the normal range; thus, orthognathic surgery without condylectomy was performed. To correct facial asymmetry successfully through orthognathic surgery, sufficient dentoalveolar decompensation must be achieved in the presurgical orthodontic phase. In cases of canting-type facial asymmetry, teeth on the nondeviated side are extruded as dentoalveolar compensation. Therefore, vertical decompensation is required for intrusion of the extruded teeth. A miniscrew and resin build-ups were used for the intrusion of teeth, and posterior segmental osteotomy was simultaneously performed with orthognathic surgery for further intrusion. The canting-type facial asymmetry was notably corrected through successful vertical decompensation and close cooperation between orthodontists and maxillofacial surgeons. After 2 years of retention, the treatment results remained stable.

Simultaneous Mandibular Anterior Segmental Osteotomy and Genioplasty: A Novel Technique.

The current standard approach to treat class II malocclusion is orthodontic preparation followed by a mandibular advancement through bilateral sagittal split osteotomy associated or not with a genioplasty. However, when a malocclusion with an important incisors' axis deviation is associated with a chin malposition, an alternative technique can be considered: simultaneous mandibular anterior segmental osteotomy and genioplasty. This technique is performed without a bony bridge between osteotomies. Care must be taken not to wound the lingual mucosa. If preserved, this technique is safe. The result is stable and predictable.

Design and implementation of a surgical planning system for robotic assisted mandible reconstruction with fibula free flap.

Free fibula flap is the gold standard for the treatment of mandibular defects. However, the existing preoperative planning protocol is cumbersome to execute, costly to learn, and poorly collaborative with the robot-assisted cutting of the fibular osteotomy plane. A surgical planning system for robotic assisted mandibular reconstruction with fibula free flap is proposed in this study. A fibular osteotomy planning algorithm is presented so that the virtual surgical planning of the fibular osteotomy segments can be obtained automatically with selected mandibular anatomical landmarks. The planned osteotomy planes are then converted into the motion path of the robotic arm, and the automatic fibula osteotomy is completed under optical navigation. Surgical planning was performed on 35 patients to verify the feasibility of our system's virtual surgical planning module, with an average time of 13min. Phantom experiments were performed to evaluate the reliability and stability of this system. The average distance and angular deviations of the osteotomy planes are 1.04 ± 0.68mm and 1.56 ±1.10°, respectively. Our system can achieve not only precise and convenient preoperative planning, but also safe and reliable osteotomy trajectory. The clinical applications of our system for mandibular reconstruction surgery are expected soon.

Three-Dimensional Comparison of the Maxillary Surfaces through ICP-Type Algorithm: Accuracy Evaluation of CAD/CAM Technologies in Orthognathic Surgery.

Purpose: This retrospective study aims to compare the accuracy of two different CAD/CAM systems in orthognathic surgery. The novelty of this work lies in the method of evaluating the accuracy, i.e., using an Iterative Closest Point (ICP) algorithm, which matches a pair of 2D or 3D point clouds with unknown dependencies of the transition from scan s(k) to scan s(k+1). Methods: The study population was composed of ten patients who presented to the Maxillofacial Surgery Department of the University “Sapienza” of Rome for the evaluation and management of skeletal malocclusions. The patients were divided into two groups, depending on the technique used: group 1: splintless group (custom-made cutting guide and plates); group 2: splint group (using a 3D-printed splint). STL files were imported into Geomagic® Control X™ software, which allows for comparison and analysis using an ICP algorithm. The RMSE parameter (3D error) was used to calculate the accuracy. In addition, data were compared in two different patient subgroups. The first subgroup only underwent a monobloc Le Fort I osteotomy (p-value = 0.02), and the second subgroup underwent a Le Fort I osteotomy associated with a segmental osteotomy of the maxilla (p-value = 0.23). Results: Group 1 showed a 3D error of 1.22 mm ± SD 0.456, while group 2 showed a 3D error of 1.63 mm ± SD 0.303. These results have allowed us to compare the accuracy of the two CAD/CAM systems (p-value = 0.09). Conclusions: The ICP algorithm provided a reproducible method of comparison. The splintless method would seem more accurate (p-value = 0.02) in transferring the surgical programming into the operating room when only a Le Fort I osteotomy is to be performed.

Closing-opening wedge osteotomy for the treatment of congenital kyphosis in children

To evaluate the safety and effectiveness of posterior closed-open wedge osteotomy for treatment of congenital kyphosis in children. Imaging and clinical data from January 2010 to December 2019 of posterior closed-open wedge osteotomy of congenital kyphosis with at least 2-year follow up was analyzed retrospectively. Perioperative indicators such as operation time, osteotomy site, osteotomy method and occurrence of complications, and imaging indicators were observed. The 3D printed models were used to measure the expanded distance of anterior edge vertebra and closed length of spinal canal line. The clinical effect was evaluated through SRS-22 questionnaires. There were 15 CK patients in this study. The osteotomy segments and details are as follows: 1 case each for T6-9 and L2, 2 cases at T11, 3 cases at T12, and 6 cases at L1. The average operation time was 314 min, the average blood loss was 970mL, the average fusion range was 6.3 segments, and the average time of follow up was 70.5 months. The Cobb angle of local kyphosis was corrected from 65.6 ± 18.8° to 11.3 ± 7.1°(p < .001). The range of kyphosis correction was 40-90°, and average correction rate was 83.2% (67.7-95.7%). The correction was stable in follow-up, and the kyphotic angle was 11.0 ± 7.6 (p = .68). The preoperative SVA was 31.5 ± 21.8mm, and the postoperative recovery was 18.0 ± 15.5, while the last follow-up was 9.1 ± 7.9. The p values were 0.02 and 0.07 respectively. By using 3D printed models, the expanded distance of anterior edge vertebra and closed length of spinal canal line were 14.5 ± 7.5mm and 24.5 ± 8.0mm respectively. Self-image and satisfaction in SRS-22 improved significantly. There was no recurrence of deformity and junctional kyphosis. The posterior closing-opening wedge osteotom for treatment of congenital kyphosis in children is satisfactory, if selected appropriately. During the longitudinal follow-up, the patients could achieve solid fusion and the correction could be well maintained.Evidence of Confidence: IVa.

Retention Strategies for Segmental Lefort I Osteotomies Using Clear Aligners.

Clear aligner therapy is becoming a mainstay of contemporary orthodontic treatment. As such wide-spread adoption and case-selection for surgical-orthodontic treatment in patients with Clear aligner therapy is increasing. Passive aligners generally lack adequate rigidity for retention of segmental movements in the immediate postoperative period. In this report we discuss our techniques for maintaining retention in the weeks after segmental maxillary osteotomies by use of a modified clear aligner orthognathic splint, and a custom palatal horseshoe splint, including the relative indications of each method.

Soft and Hard Tissue Changes and Facial Rejuvenation of Anterior Maxillary Segmental Osteotomy: A Three-Dimensional Cephalometric Study.

To explore the efficacy of anterior maxillary segmental osteotomy (AMSO) in reliving maxillary protrusion and better analyze the three-dimensional (3D) morphological changes of the postoperative nasolabial region using computed tomography (CT) and evaluate the trend of facial rejuvenation. Forty-five patients who underwent AMSO from January 2017 to December 2021 were retrospectively included. CT and oriented photography were performed before and 10 months after the treatment. The mimics17.0 software was used to reconstruct the 3D CT scan results before and after the operation, measure the data of each anatomical index, and systematically evaluate the soft tissue changes in the nasolabial region. The patients themselves, the plastic surgeons, family members, or friends of patients use the Face-Q Age Appraisal Visual Analogue Scale (VAS) to evaluate the changes in patients' visual age before and after the operation. Forty-five cases of maxillary protrusion were alleviated.Seen from the side, the protruding degree of the upper lip is obviously reduced.In the front view,∠Cont-Sbal-F, the width of alar base, andalae nasi all increased significantly. Contrary to traditional perceptions, the protrusion and height of the nose tip actually increased rather than decreased after AMSO. The visual age score improved positively, and patients obtained facial rejuvenation. No serious complications occurred; after 10-month follow-up, we achieved a high degree of satisfaction. AMSO can significantly improve the maxillary protrusion, and it can increase the protrusion and height of the nose tip. Also, patients can get a younger appearance. Comprehensive preoperative evaluation and postoperative nasolabial morphology with maxillary protrusion patients are helpful for correct clinical decision-making. At the same time, the operation suggests a new choice of facial rejuvenation for patients with maxillary protrusion. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

The role of anterior segmental osteotomies in orthognathic surgery for protrusive faces in a Southeast Asian population: 10-year retrospective data of 51 patients treated in a single centre

Bimaxillary protrusion is a dentofacial deformity common in the East Asian population. It is often difficult to decide between orthodontic and surgical retraction to treat patients with bimaxillary protrusion, especially if surgery to correct skeletal base discrepancies is also required. The objective of this study was to investigate the treatment outcomes of surgical versus orthodontic retraction in patients with bimaxillary protrusion undergoing orthognathic surgery. A retrospective cohort study was conducted, where the medical records and radiographs of 51 patients with bimaxillary protrusion who had an anterior segmental osteotomy concomitant with orthognathic surgery were examined. Patients who had bimaxillary anterior segmental osteotomies were more likely to achieve an inter-incisal angle of 135 ± 5° at the end of treatment, when compared to patients who had orthodontic retraction (P < 0.01). The total treatment duration of patients who had bimaxillary anterior segmental osteotomies was significantly shorter as compared to that of the patients who only had these osteotomies in the maxilla (P < 0.001) or mandible (P = 0.012). Complications and permanent long-term sequelae following anterior segmental osteotomies were uncommon. It is concluded that bimaxillary anterior segmental osteotomies are a viable alternative for patients with concomitant bimaxillary protrusion and skeletal base discrepancies. This allows for a significantly shorter treatment time and greater correction of inter-incisal angles, without a significant increase in complications.

Clinical Results of Utilizing the Satellite Rod Technique in Treating Ankylosing Spondylitis Kyphosis

ObjectiveAccording to the literature, there are no clinical reports documenting the use of the satellite rod technique in the treatment of ankylosing spondylitis kyphosis. The purpose of this retrospective study was to compare the clinical outcome of patients with ankylosing spondylitis kyphosis who adopted satellite rods versus those who did not.MethodsPatients with ankylosing spondylitis kyphosis who underwent one or two‐level pedicle subtraction osteotomy (PSO) were reviewed, and total of 119 patients (112 males and seven females, average age 39.89 ± 6.61 years) were eligible and included in this present study. Anterior–posterior and lateral full‐length spine X‐ray films were performed preoperatively and at the two‐year follow‐up visit. Global kyphosis (GK), lumbar lordosis (LL), thoracolumbar kyphosis (TLK), thoracic kyphosis (TK), and osteotomy angle (OA) were measured. The complications of every group of patients were collected. Pre‐ and postoperative health‐related quality of life instruments, including the Bath Ankylosing Spondylitis Functional Index (Basfi) and Scoliosis Research Society outcomes instrument‐22 (SRS‐22), were recorded. The patients were divided into three groups based on features of their osteotomy including PSO levels and whether the satellite rod technique was applied. Patients who underwent one‐level PSO without the satellite rod technique were categorized in the one‐level group. Patients who underwent one‐level PSO with the satellite rod technique were classified in the satellite rod group. Patients who underwent two‐level PSO without the satellite rod technique were included in the two‐level group. The paired sample t test was used to compare pre‐ and postoperative parameters. One‐way ANOVA was performed for multiple group comparisons.ResultsThe average follow‐up time is 29.31 ± 3.66 months. The patients' GK were significantly improved from 46.84 ± 20.37 degree to 3.31 ± 15.09 degree. OS achieved through each osteotomy segment of one‐level group (39.78 ± 12.29 degree) and satellite rods group (42.23 ± 9.82 degree), was larger than that of two‐level group (34.73 ± 7.54 and 28.85 ± 7.26 degree). There was no significant difference between the one‐level group and the satellite rod group in achieving the OS. Thirteen patients experienced different complications (10.92%). Three patients experienced rod fracture in the one‐level group. There was no rod fracture or screw failure in the satellite rod group or the two‐level group.ConclusionThe satellite rod technique is also recommended for patients who undergo PSO osteotomy to correct ankylosing spondylitis kyphosis deformities.

A Look Back: A Single Surgeon's Experience Using Virtual Surgical Planning in Adult Orthognathic Surgery.

The evolution of virtual surgical planning (VSP) in the last 2 decades has led to improved precision and efficiency for orthognathic surgery, both pre- and intraoperatively. This study evaluates a single surgeon's experience with this technology over the past 6 years. Patients undergoing orthognathic surgery using VSP with the senior author between 2015 and 2021 were retrospectively reviewed. Virtual surgical planning -specific data including incidence of midline/cant correction, occlusal equilibration, serial splints, segmental osteotomies, and custom plates were recorded and analyzed. Sixty patients undergoing orthognathic surgery using simulated VSP in the study period were retrospectively reviewed. Mean age at time of surgery was 23.5±7.9 years. Forty-nine patients (81.7%) underwent LeFort I osteotomy combined with at least 1 additional procedure (eg,unilateral or bilateral sagittal split osteotomy, condylectomy, genioplasty, etc.). Twenty-six (43.3%) of patients in the studied cohort underwent maxillary midline correction, 30.0% required occlusal equilibration, 36.7% underwent maxillary molar cant correction, 30.0% underwent mandibular cant correction, and 21.7% required both maxillary and mandibular cant correction. Three patients required serial splinting, and 15 patients (25.0%) required modification of splint design. Custom plates were utilized in 15 patients (25.0%). This study demonstrates the utility of VSP in accurately detecting occlusal cants, asymmetry, and occlusal interferences. Virtual surgical planning also allows for a dynamic preoperative planning process, offering the surgeon a high degree of versatility in splint design, and the ability to fabricate multiple customized splints for each case. This is particularly useful in patients with limited or unpredictable soft tissue elasticity.

Comparison of Propofol-Fentanyl Versus Propofol-Ketamine Combination as Total Intravenous Anesthesia in Maxillofacial Surgical Procedures – A Prospective Randomized Controlled Study

Background: Total intravenous anesthesia (TIVA) is a technique where drugs are administered intravenously for the induction and maintenance of anesthesia instead of volatile drugs, avoiding some of the drawbacks of inhalation anesthesia providing rapid and complete recovery making it suitable for daycare surgeries. Aim: To compare the intraoperative and postoperative hemodynamic patterns, postoperative recovery time, and unwanted consequences such as post-operative nausea and vomiting (PONV) in various maxillofacial procedures using a combination of two drug regimens, namely propofol-ketamine and propofol-fentanyl. Patient &amp; methods: 40 patients between the age group of 18-40 years of either gender were randomly divided into two groups with propofol-ketamine (group 1, n=20) and propofol-fentanyl (group 2, n=20) who underwent various surgical procedures like cyst enucleation, open reduction and internal fixation (ORIF) of facial fractures, orthognathic procedures such as maxillary or mandibular segmental osteotomy and genioplasty with the procedure lasting 60 to 75 minutes. This study compared the total amount of propofol, time of the infusion, and hemodynamic parameters like mean pulse rate (PR), oxygen saturation level (SpO2), systolic blood pressure (SBP) &amp; diastolic blood pressure (DBP), emergence time &amp; recovery time, undesirable sequels like postoperative nausea and vomiting (PONV) and any other side effects between both the groups. Results were analyzed statistically using an independent t-test and chi-square test. Results: A comparison of two groups revealed a significant rise in systolic blood pressure in group 1 as compared to group 2 and group 2 showed better emergence time &amp; recovery time with fewer incidences of postoperative nausea and vomiting and other side effects. Conclusion: Since the propofol-fentanyl provided significantly good results it can be considered as an alternative to gaseous anesthetic agents in various maxillofacial surgical procedures mentioned in the materials with the surgical procedure lasting 60-75 minutes.

Personal Guide Assisted Orthognathic Surgery: Application of a T-shaped Tooth Bone Combined Supporting Osteotomy Guide Plate and Positioning Guide Plate.

The precise movement of the maxilla is particularly important for orthognathic surgery, especially for patients with maxillary segmentation. In this preliminary study, the authors present a new tooth bone combined with a supporting osteotomy guide and positioning guide to guide the osteotomy and reduction of the maxilla. Through our preoperative simulation and postoperative image fusion, the authors found that the overlapping area is more than 90%. According to compare of the virtual plans and the postoperative results based on distances from the maxillary land- marks to the horizontal plane, sagittal plane, and coronal plane, the surgical error was about 2mm. Our T-shaped guide provides a reliable method for patients with maxillary segmental osteotomy, which may be a useful alternative to the intermediate.

The Open Book Genioplatsy Technique: A Modification.

Genioplasty is a versatile procedure in the repertoire of a maxillofacial surgeon since the time it was conceptualized by Trauner and Obwegeser in 1957.1 The chin improves the facial profile and renders a definition to the jaw. An aligned and proportionate chin adds ample aesthetic value and youthfulness to the face. In addition, it influences the apparent length of the face. Genioplasty holds the potential to alter the dynamics of facial harmony with minimal effort.2 Failure to perform a much required genioplasty can jeopardize the outcome of hours of an otherwise successful major orthognathic or cosmetic surgery.3 The slope and nature of rotation of the osteotomized segments dictate the extent of vertical and horizontal changes.4 In this article, we attempt to introduce a modification to the existing plethora of genioplasty techniques, particularly aimed to rectify a short square jaw into a feminine one. This technique comprises two conventional oblique osteotomies that split the chin into two components, superior and inferior. A margin of 5 mm is kept superiorly from the root tip, inferiorly from the lower border of mandible, and laterally from the mental foramen. Additional stripping of muscles along the lower border of the mandible ensures adequate mobility of the osteotomized inferior segment. The osteotomized segment is rotated outward and downward at an angle of about 30 to 40 degrees, wherein the tip of the inferior osseous segment is regarded as the prominence of the newfound mentum and the anterior surface of the chin becomes the lower border of the mandible (Fig. 1). The osseous segments are secured using two four-hole, 2.0-mm titanium plates (Fig. 2). Bony margins are smoothed. Hemostasis is achieved. Closure is performed done using 4-0 Vicryl sutures. A 1-year pictorial and radiographic follow-up is charted. The same substantiates the successful outcome of the procedure in terms of desired vertical increment, horizontal augmentation, a feminine round chin with a pointy upheal, and desired labiomental fold.Fig. 1.: Schematic representation of the open book genioplasty technique, in which point A becomes the newfound chin prominence, B becomes the lower border of the mandible, and C is the thickness of the mandible seen upon rotation.Fig. 2.: Osseous segment secured using titanium plates and screws depicting an open book fixation.The design of this open book osteotomy can be deemed ideal for a patient with an existing broad chin who desires a sharper, more feminine one. We have so far performed this procedure on female patients, who require a horizontal advancement of about 10 to 13 mm. The greatest advantage lies in negating a step formation along the lower border of the mandible, contributing to a smooth jawline. The downward rotation of the inferior segment helps acquire additional length, thus leading to a vertical increment in the lower half of the face. The possibility of a dual-plane augmentation makes this technique a versatile one. The thickness of the mentum is a vital consideration, as the osseous volume directly translates to the extent of advancement that can be achieved. In our vast clinical experience, the proposed open book genioplasty technique has had gratifying results with the desired osseous and soft-tissue outcomes in female patients with a short, square chin. ACKNOWLEDGMENT This study conformed to all guidelines of the Declaration of Helsinki. DISCLOSURE The authors have no financial interest to declare in relation to the content of this article. No funding was received for this work.

Corrective osteotomy for complex tibial deformity in a patient with hereditary vitamin D-resistant hypophosphatemic rickets (HVDRR) using CT-based navigation system and 3D printed osteotomy model

Planning a three-dimensional (3D) osteotomy using computed tomography (CT) data is useful especially in cases with complex deformities. Furthermore, CT-based navigation system allows the preoperative virtual planning to be replicated in actual surgery. However, one disadvantage when using navigation systems is that when osteotomies are performed on tracker-attached bone, the bone fragments on the side that were cut away cannot be tracked. This is especially problematic when performing multiple osteotomies on bones with complex deformities. We solved this problem by creating a 3D printed bone model that can be referenced intraoperatively and used in combination with the navigation system. We applied these techniques to perform segmental corrective osteotomy for a complex tibial deformity with intramedullary nail (IMN) fixation case of hereditary vitamin D-resistant hypophosphatemic rickets (HVDRR) in an adult man. Due to the patient’s history of multiple surgeries, the affected tibia had a narrow and partially closed medullary canal. Therefore, we planned to use an IMN for correction and fixation of tibial deformity to protect the thin and stretched skin around the deformed tibia. With the assistance of CT-based navigation, we could perform an accurate three-dimensional tibial osteotomy. Moreover, we could perform accurate preparation of closed medullary canal for the IMN placement by referring to the 3D printed bone models. Six months after the operation, the bone union at the osteotomy sites was confirmed and the patient was able to return to his normal life and work.

Active Unilateral Condylar Hyperplasia Treated With Simultaneous Condylectomy and Orthognathic Surgery: A Clinical Report

To review and report the demographic and diagnostic data in a population with active unilateral condylar hyperplasia. The surgical intervention, sequencing of surgery, and treatment outcomes, including a quality-of-life survey, are described. Eighty patients were diagnosed with active disease. Demographic, treatment, and treatment outcomes were assessed. Quality of life was assessed by a 21-question questionnaire. Women were affected more frequently than men (W- 52; 65%; P = .008). Hemimandibular elongation (HE) (49; 61%; P - .004) occurred more frequently than hemimandibular hyperplasia (HH) (24; 30%) and HH-HE (7; 9%). Right side was affected more than left (R- 49; 61%; P - .003) overall, and when stratified. All racial groups were represented. Of the 80 patients in the sample, 80 (100%) underwent condylectomy on the side of active growth, 70 (87%) underwent bimaxillary osteotomies, 53 patients (66%) had single-piece maxillary osteotomies, 17 (21%) underwent segmental maxillary osteotomies, and 38 (48%) genioplasties were performed. Four patients (5%) underwent a second operation within a year of the first surgery to adjust the position of the mandible. Four (5%) facial nerve deficits were recorded. Class I cuspid occlusion was achieved with coincident maxillary and mandibular midlines and resolution of crossbite in 70 (88%) patients. Twenty three of the 24 respondents (96%) reported that they were satisfied with the treatment. Both HH and HE are diagnosed through clinical and radiographic examinations. Our results showed that HE occurs more frequently, all deformity subclassifications occur more frequently in females, the majority present in adolescence, and all racial groups are affected. The right side predominated. This study suggests that simultaneous condylectomy and orthognathic surgery provides predictable and stable outcomes for patients with active unilateral condylar hyperplasia and associated dentofacial deformities with an improvement in quality of living.

Biomechanical Evaluation of Seven Fixation Methods for Sagittal Split Ramus Osteotomy with Four Advancement Levels by Finite Element Analysis.

BackgroundMandibular sagittal split ramus osteotomy (SSRO) is a routine surgery to correct mandibular deformities, such as mandibular retrusion, protrusion, deficiency, and asymmetry. However, nonunion/malunion of the fragments and relapse caused by fixation failure after SSRO are major concerns. Rigid fixation to maintain postosteotomy segmental stabilization is critical for success. Additionally, understanding the biomechanical characteristics of different fixation methods in SSRO with large advancements is extremely important for clinical guidance. Therefore, the aim of the present study was to evaluate the biomechanical characteristics of different SSRO methods by finite element analysis.MethodsSSRO finite element models with 5-, 10-, 15-, and 20-mm advancements were developed. Seven fixation methods, namely, two types of bicortical screws, single miniplate, dual miniplates, grid plate, dual L-shaped plates, and hybrid fixation, were positioned into the SSRO models. Molar and incisal biomechanical loads were applied to all models to simulate bite forces. We then investigated the immediate postoperative stability from four aspects, namely, the stability of the distal osteotomy segment, osteotomy regional stability, stress distribution on the mandible, and implant stress performance.ResultsThe stability of the distal osteotomy segment and osteotomy region decreased when the advancement increased. All seven fixation methods displayed favorable biomechanical stability under minor advancement (5 mm). With large advancements, bicortical screws, dual miniplates, and grid plates provided better stability. The von Mises stress was concentrated around the screws close to the osteotomy region for the proximal segment for all fixation methods, and the von Mises stress on implants increased with larger advancements. With small advancements, five fixation methods endured tolerable maximum stresses of <880 MPa. A single miniplate and dual L-shaped plates generally suffered high stresses using larger advancements. The biomechanical characteristics were similar under molar and incisal loads.ConclusionsThe current study investigated the biomechanical properties of seven fixation devices after SSRO under molar and incisal loads. Generally, bicortical screws, grid plates, and dual miniplates provided better biomechanical stability using finite element analysis.

Posterior Mandibular Segmental Split Osteotomy: A Novel Technique for Edentulous Space Reconstruction in Patients With Skeletal Class III Malocclusion.

This study presents an innovative surgery that successfully improved the facial profile and occlusal function of a patient with a skeletal Class III malocclusion and posterior hypodontia. The patient had chief complaints of missing teeth and a protrudedjaw. A novel 1-stage surgery referred to as posterior mandibular segmental split osteotomy combined with Le Fort i osteotomy and BSSRO was used because the patient wanted to save time and was worried about periodontal complications associated with other treatment methods. As a result, a satisfying facial profile and a Class I occlusion with a normal position of the posterior dentoalveolar segment of the mandible were achieved with no adverse effects. Thus, posterior mandibular segmental split osteotomy can be considered an effective treatment for skeletal Class III malocclusion with posterior hypodontia.

Effect of Concentrated Growth Factor on Distraction Osteogenesis of Dental Implant Distractors

The periosteum of bone segments can be destroyed during the installation of a dental implant distractor (DID) device, resulting in bone defects on the exposed side of the distraction gap. The purpose of this animal experiment is to explore the application of concentrated growth factor (CGF) in DID surgery, which can induce angiogenesis and osteogenesis and improve osteogenesis defects caused by periosteum loss on the exposed side of bone segments. CGF is the latest generation of platelet concentrate. Twenty-four DID devices inserted into the tibias of 8 goats were evenly divided into the CGF and control groups. Following 10days of distraction and a 12-week consolidation period, all 8 animals were euthanized to retrieve their tibias. The distraction gap between each segment was measured at 5 points, and the average value was taken as the computed tomography (CT) value of the distraction gap at 4, 8, and 12weeks after distraction. The vascular density and trabecular bone volume of each DID distraction gap were determined and statistically compared between the 2 groups. The CT value of the distraction gap increased gradually in control groups at 4, 8, and 12weeks after distraction to 319.3±14.6, 449.3±34.4, and 614.0±15.6 HU in the control group and 368.3±8.8, 544.5±12.3, and 661.0±8.1 HU in the CGF group. The trabecular bone volume was 281.7±16.5 and 209.7±21.6μm2 in the CGF group and control group. The vascular density was 17.7±2.1 and 11.7±1.9 in the CGF group and control group. Statistically significant differences were observed in the CT value (P=.002), vascular density (P=.023), and trabecular bone volume (P=.010) between the CGF and control groups. The application of an autogenous CGF membrane in DID surgery repaired bone defects caused by osteolysis around osteotomy segments.

Biomechanical Analyses of Porous Designs of 3D-Printed Titanium Implant for Mandibular Segmental Osteotomy Defects.

Clinically, a reconstruction plate can be used for the facial repair of patients with mandibular segmental defects, but it cannot restore their chewing function. The main purpose of this research is to design a new three-dimensionally (3D) printed porous titanium mandibular implant with both facial restoration and oral chewing function reconstruction. Its biomechanical properties were examined using both finite element analysis (FEA) and in vitro experiments. Cone beam computed tomography images of the mandible of a patient with oral cancer were selected as a reference to create 3D computational models of the bone and of the 3D-printed porous implant. The pores of the porous implant were circles or hexagons of 1 or 2 mm in size. A nonporous implant was fabricated as a control model. For the FEA, two chewing modes, namely right unilateral molar clench and right group function, were set as loading conditions. Regarding the boundary condition, the displacement of both condyles was fixed in all directions. For the in vitro experiments, an occlusal force (100 N) was applied to the abutment of the 3D-printed mandibular implants with and without porous designs as the loading condition. The porous mandibular implants withstood higher stress and strain than the nonporous mandibular implant, but all stress values were lower than the yield strength of Ti-6Al-4V (800 MPa). The strain value of the bone surrounding the mandibular implant was affected not only by the shape and size of the pores but also by the chewing mode. According to Frost’s mechanostat theory of bone, higher bone strain under the porous implants might help maintain or improve bone quality and bone strength. The findings of this study serve as a biomechanical reference for the design of 3D-printed titanium mandibular implants and require confirmation through clinical investigations.