The use of virtual reality and augmented reality in oral and maxillofacial surgery: A narrative review.

OBJECTIVE: The purpose of this article is to review the current uses of virtual reality (VR) and augmented reality (AR) in oral and maxillofacial surgery. We discuss the use of VR/AR in educational training, surgical planning, advances in hardware and software, and the implementation of VR/AR in this field. STUDY DESIGN: A retrospective comprehensive review search of PubMed, Web of Science, Embase, and Cochrane Library was conducted. The search resulted in finding 313 English articles in the last 10 years. RESULTS: A total of 38 articles were selected after a meticulous review of the aims, objectives, and methodology by 2 independent reviewers. CONCLUSIONS: Virtual reality/AR technology offers significant potential in various aspects, including student education, resident evaluation, surgical planning, and overall surgical implementation. However, its widespread adoption in practice is hindered by factors such as the need for further research, cost concerns, unfamiliarity among current educators, and the necessity for technological improvement. Furthermore, residency programs hold a unique position to influence the future of oral and maxillofacial surgery. As VR/AR has demonstrated substantial benefits in resident education and other applications, residency programs have much to gain by integrating these emerging technologies into their curricula.

Nonvascularized bone grafts: how successful are they in reconstruction of segmental mandibular defects?

OBJECTIVE: Segmental mandibular defects can occur due to various etiologies, including trauma and tumor resection. Reconstruction should provide adequate support for subsequent dental rehabilitation and allow for proper occlusion. Nonvascularized bone grafts have been used for reconstructing mandibular defects in cases where vascularized grafts were not feasible. The objective of this study was to assess the success rate of these grafts in reconstruction of segmental defects of various sizes in the mandible. STUDY DESIGN: Fifty patients were included in this retrospective chart review. Length of the grafts varied from 3 to 20 cm and patients were followed up from 4 to 80 months. Fifteen grafts were harvested from anterior iliac crest, 23 from posterior iliac crest, 9 grafts were a combination of either with costochondral graft, and 3 were solely allografts. Bone morphogenetic protein was utilized in 41 cases as an adjunct. RESULTS: Success was defined as continuity of bone clinically and radiographically at a 4-month follow-up. Nonvascularized bone grafting was successful in 90% of cases. Complications were observed in 34% of cases, of which the most common were infection followed by wound dehiscence. CONCLUSIONS: Our study demonstrated substantial success rate with nonvascularized bone grafts in reconstruction of segmental mandibular defects.

The use of clear aligners in orthognathic surgeries: a case series.

Pre- and postoperative fixed orthodontic appliances are the customary and standard practice for patients with treatment planned for undergoing orthognathic surgery. Traditionally, most patients undergoing orthognathic surgeries are in their late teens. Although these patients still compose the greatest pool of the orthognathic surgery population, many patients seek orthognathic surgery later in life. This older patient population often has different concerns and goals than the younger patient population. One of these concerns is often the aesthetic appearance of fixed appliances and the time required to wear these appliances pre- and postoperatively. Today, removable orthodontic appliances consisting of a series of clear aligners have gained immense popularity due to their aesthetic appeal over traditional braces. Additional benefits of removable orthodontic appliances include improved oral hygiene leading to a decreased risk of gingivitis. Whereas clear aligner systems are commonly used in the nonsurgical orthodontic population, there has been limited use of Invisalign in the orthognathic surgery population. In this article, we present a case series of 5 patients who successfully underwent orthognathic surgery using clear aligners for pre- and postoperative orthodontic treatment.

Biomechanical and Mechanostat analysis of a titanium layered porous implant for mandibular reconstruction: The effect of the topology optimization design.

A porous scaffold/implant is considered a potential method to repair bone defects, but its mechanical stability and biomechanics during the repair process are not yet clear. A mandibular titanium implant was proposed and designed with layered porous structures similar to that of the bone tissue, both in structure and mechanical properties. Topology was used to optimize the design of the porous implant and fixed structure. The finite element analysis was combined with bone "Mechanostat" theory to evaluate the stress and osteogenic property of the layered porous implant with 3 different fixation layouts (Model I with 4 screws, Model II with 5 screws and Model III with 6 screws) for mandibular reconstruction. The results showed that Model III could effectively reduce the stress shielding effect, stress within the optimized implant, defective mandible, and screws were respectively dropped 48.18%, 44.23%, and 57.27% compared to Model I, and the porous implant had a significant stress transmission effect and maintained the same stress distribution as the intact mandible after the mandibular defect was repaired. The porous implant also showed a significant mechanical stimulation effect on the growth and healing of the bone tissue according to the bone "Mechanostat" theory. The combination of porous structure with the topology technique is a promising option to improve the mechanical stability and osteogenesis of the implant, and could provide a new solution for mandibular reconstruction.

Identification of Body Dysmorphic Disorder in Patients Seeking Corrective Procedures From Oral and Maxillofacial Surgeons.

INTRODUCTION: Body dysmorphic disorder (BDD) is an obsessive-compulsive related disorder characterized by an individual's preoccupation with the appearance of at least 1 perceived physical flaw. The bodily concerns held by individuals with BDD are largely unnoticeable, if at all, to other individuals. Those living with BDD are compelled to engage in repetitive behaviors or cognitive acts that interfere with daily function and activities. Despite the high prevalence of BDD in patients who seek cosmetic procedures (ie, as high as 1 in 5 such patients) and the availability of validated screening tools for this disorder, implementing a protocol of regularly screening for BDD is only rarely practiced by surgeons. Few studies have investigated its prevalence in the setting of elective dentoalveolar and orthognathic procedures. With the scope of practice of maxillofacial surgeons expanding in recent years to include facial cosmetic procedures, it is becoming increasingly important to screen for such disorders so that patients and physicians can appropriately weigh the risks and benefits of surgical intervention. METHODS: We conducted a cross-sectional cohort study (n = 46) consisting of 3 groups of patients, who were seeking either facial cosmetic, orthognathic, or dentoalveolar procedures. All patients in the study were screened for BDD using the Body Dysmorphic Disorder Questionnaire (BDDQ) and assessed for severity of disorder using the BDDQ severity scale. Additional patient variables included age, sex, history of psychiatric diagnosis, primary diagnosis, and type of operation/procedure being sought. RESULTS: Among the 3 groups, patients seeking dentoalveolar surgery were the most represented (67%) in this sample, followed by cosmetic surgery (27%) and orthognathic surgery (6%). Twenty-six female participants and 20 male participants were included, with an overall mean age of 38 years. Two percent of participants carried a previous psychiatric diagnosis and 10.8% of the sample were classified as high-risk for BDD. The group containing the highest proportion of patients at high-risk for BDD were those seeking facial cosmetic procedures (16.7%), followed by those seeking dentoalveolar procedures (10%); none of the patients seeking orthognathic procedures were found to be at high-risk for BDD (0%). CONCLUSIONS: The BDDQ is an efficient way to screen for BDD in patients who are seeking orthognathic or facial cosmetic surgery. In our sample, patients presenting to maxillofacial surgeons for facial cosmetic surgery were found to score significantly higher on the BDDQ than those presenting for dentoalveolar surgery. In contrast to results of previous literature, patients seeking orthognathic surgery in our sample demonstrated no elevated risk for BDD, a finding which may be attributable to our small sample size. Ultimately, the data obtained from this study can aid surgeons in identifying patients with BDD in their own surgical practice, so that they may appropriately triage patients who may, or may not, benefit from surgical intervention.

Experimental validation of finite element simulation of a new custom-designed fixation plate to treat mandibular angle fracture.

BACKGROUND: The objective of the study was to validate biomechanical characteristics of a 3D-printed, novel-designated fixation plate for treating mandibular angle fracture, and compare it with two commonly used fixation plates by finite element (FE) simulations and experimental testing. METHODS: A 3D virtual mandible was created from a patient's CT images as the master model. A custom-designed plate and two commonly used fixation plates were reconstructed onto the master model for FE simulations. Modeling of angle fracture, simulation of muscles of mastication, and defining of boundary conditions were integrated into the theoretical model. Strain levels during different loading conditions were analyzed using a finite element method (FEM). For mechanical test design, samples of the virtual mandible with angle fracture and the custom-designed fixation plates were printed using selective laser sintering (SLS) and selective laser melting (SLM) printing methods. Experimental data were collected from a testing platform with attached strain gauges to the mandible and the plates at different 10 locations during mechanical tests. Simulation of muscle forces and temporomandibular joint conditions were built into the physical models to improve the accuracy of clinical conditions. The experimental vs the theoretical data collected at the 10 locations were compared, and the correlation coefficient was calculated. RESULTS: The results show that use of the novel-designated fixation plate has significant mechanical advantages compared to the two commonly used fixation plates. The results of measured strains at each location show a very high correlation between the physical model and the virtual mandible of their biomechanical behaviors under simulated occlusal loading conditions when treating angle fracture of the mandible. CONCLUSIONS: Based on the results from our study, we validate the accuracy of our computational model which allows us to use it for future clinical applications under more sophisticated biomechanical simulations and testing.

Medication-related osteonecrosis of the jaw: An institution's experience.

OBJECTIVES: This study aimed to evaluate and report the outcomes associated with the management of patients who were treated surgically for medication-related osteonecrosis of the jaw (MRONJ).Methods: Demographic and medical profiles of patients with a diagnosis of MRONJ were created. The type of surgical treatment, complications, and treatment outcomes were identified.Results: Twenty-one patients with an average age of 68.42 years (range 40-90 years) were included. Nineteen patients had only mandible involvement, one patient had only maxilla involvement, and one patient had both mandible and maxilla involvement. Thirteen patients underwent marginal resections. Eight patients underwent segmental resection of the mandible with immediate reconstruction. Nineteen patients healed without any complications. Two patients who had undergone segmental resection of the mandible experienced postoperative complications and needed a second surgery to achieve primary closure.Discussion: Advanced MRONJ can effectively be treated with resective surgery in combination with medical treatment.

Biallelic PTCH1 Inactivation Is a Dominant Genomic Change in Sporadic Keratocystic Odontogenic Tumors.

Keratocystic odontogenic tumors (KCOTs) are locally aggressive odontogenic neoplasms with recurrence rates of up to 60%. Approximately 5% of KCOTs are associated with nevoid basal cell carcinoma (Gorlin) syndrome and 90% of these show genomic inactivation of the PTCH1 gene encoding Patched 1. Sporadic KCOTs reportedly have PTCH1 mutations in 30% of cases, but previous genomic analyses have been limited by low tumor DNA yield. The aim of this study was to identify recurrent genomic aberrations in sporadic KCOTs using a next-generation sequencing panel with complete exonic coverage of sonic hedgehog (SHH) pathway members PTCH1, SMO, SUFU, GLI1, and GLI2. Included were 44 sporadic KCOTs from 23 female and 21 male patients with a median age of 50 years (range, 10 to 82 y) and located in the mandible (N=33) or maxilla (N=11). Sequencing identified PTCH1 inactivating mutations in 41/44 (93%) cases, with biallelic inactivation in 35 (80%) cases; 9q copy neutral loss of heterozygosity targeting the PTCH1 locus was identified in 15 (34%) cases. No genomic aberrations were identified in other sequenced SHH pathway members. In summary, we demonstrate PTCH1 inactivating mutations in 93% of sporadic KCOTs, indicating that SHH pathway alterations are a near-universal event in these benign but locally aggressive neoplasms. The high frequency of complete PTCH1 loss of function may provide a rational target for SHH pathway inhibitors to be explored in future studies.

Bionic mechanical design and 3D printing of novel porous Ti6Al4V implants for biomedical applications.

In maxillofacial surgery, there is a significant need for the design and fabrication of porous scaffolds with customizable bionic structures and mechanical properties suitable for bone tissue engineering. In this paper, we characterize the porous Ti6Al4V implant, which is one of the most promising and attractive biomedical applications due to the similarity of its modulus to human bones. We describe the mechanical properties of this implant, which we suggest is capable of providing important biological functions for bone tissue regeneration. We characterize a novel bionic design and fabrication process for porous implants. A design concept of "reducing dimensions and designing layer by layer" was used to construct layered slice and rod-connected mesh structure (LSRCMS) implants. Porous LSRCMS implants with different parameters and porosities were fabricated by selective laser melting (SLM). Printed samples were evaluated by microstructure characterization, specific mechanical properties were analyzed by mechanical tests, and finite element analysis was used to digitally calculate the stress characteristics of the LSRCMS under loading forces. Our results show that the samples fabricated by SLM had good structure printing quality with reasonable pore sizes. The porosity, pore size, and strut thickness of manufactured samples ranged from (60.95± 0.27)% to (81.23±0.32)%, (480±28) to (685±31) µm, and (263±28) to (265±28) µm, respectively. The compression results show that the Young's modulus and the yield strength ranged from (2.23±0.03) to (6.36±0.06) GPa and (21.36±0.42) to (122.85±3.85) MPa, respectively. We also show that the Young's modulus and yield strength of the LSRCMS samples can be predicted by the Gibson-Ashby model. Further, we prove the structural stability of our novel design by finite element analysis. Our results illustrate that our novel SLM-fabricated porous Ti6Al4V scaffolds based on an LSRCMS are a promising material for bone implants, and are potentially applicable to the field of bone defect repair.

Analysis of biomechanical behavior of 3D printed mandibular graft with porous scaffold structure designed by topological optimization.

BACKGROUND: Our long-term goal is to design and manufacture a customized graft with porous scaffold structure for repairing large mandibular defects using topological optimization and 3D printing technology. The purpose of this study is to characterize the mechanical behavior of 3D printed anisotropic scaffolds as bone analogs by fused deposition modeling (FDM). METHODS: Cone beam computed tomography (CBCT) images were used to reconstruct a 3D mandible and finite element models. A virtual sectioned-block of the mandible was used as the control group and the trabecular portion of the block was modified by topological optimization methods as experimental groups. FDM (FDM) printed samples at 0, 45 and 90 degrees with Poly-lactic acid (PLA) material under a three-point bending test. Finite element analysis was also used to validate the data obtained from the physical model tests. RESULTS: The ultimate load, yield load, failure deflection, yield deflection, stress, strain distribution, and porosity of scaffold structures were compared. The results show that the topological optimized graft had the best mechanical properties. CONCLUSIONS: The results from mechanical tests on physical models and numerical simulations from this study show a great potential for topological optimization and 3D printing technology to be served in design and rapidly manufacturing of artificial porous grafts.

Biomechanical behavior of mandibles reconstructed with fibular grafts at different vertical positions using finite element method.

BACKGROUND: For large mandibular defects, surgical reconstruction using microvascular fibular grafts has advantages over other alternatives in terms of blood supply and good quality of grafted bone. However, the fibular segment is usually lower in height than that of the original mandible, meaning that the vertical positioning of the fibular graft is variable, with different biomechanical consequences on the reconstructed mandible. OBJECTIVES: To use finite element method (FEM) to evaluate stress distribution and displacement of a reconstructed mandible versus an intact mandible under occlusal loads. METHODS: A three-dimensional intact edentulous mandibular bone (Model I) and a reconstructed mandible bone with fibular graft were created from CBCT images. Calculation models were generated with fibular bone graft extracted from the reconstructed mandible of identical length placed into a mimicked defect area on the right-hand side of the mandible at three different vertical positions: superior (Model II), intermediate (Model III), and inferior (Model IV). Forces were applied at lower left first molar region and lower left central incisor area. Von Mises stresses and mandibular displacement were calculated as outcome measurements during loadings. RESULTS: Maximum stress and strain within the reconstructed mandible were identified at the posterior border of the graft and the contralateral condyle. Maximum displacement occurred near the interface of fibular graft and anterior segment of the mandible. Stress distribution in the graft under functional loads is much higher than that in the residual mandibular segments from Models II to IV. The combined average maximum stress from anterior and posterior loads is 10.66 times higher in the mandible with inferiorly positioned graft (Model IV), 8.72 times for superior graft (Model II), and 3.68 times for intermediate graft (Model III) than that in the control group (Model I). The worst displacement result during functional loadings was in the group with fibular graft located at the inferior border of the mandible. CONCLUSIONS: The position of fibular graft placed in the surgical resection site has significant effects on the mechanical behavior of the reconstructed mandible. The fibular graft aligned with the inferior border of the mandible, the most common site designated location by clinicians, has the worst effects on the stress distribution and displacement to the mandibular under functional loads. The fibular graft placed at the intermediate location has the best biomechanics and provides favorable condition for subsequent prosthetic reconstruction.

Quantification of volumetric, surface area and linear airway changes after orthognathic surgery: a preliminary study.

PURPOSE: The aim of this study was to conduct a retrospective evaluation of the volumetric, cross-sectional surface area and the linear airway changes in healthy subjects undergoing orthognathic surgery. MATERIALS AND METHODS: A total of 10 patients were included in this study and categorized into two groups. The first group consisted of five patients who underwent maxillary and mandibular advancements (MMA) with genioplasty. The remaining five patients who underwent maxillary advancement with mandibular setback (MAMS) comprised the second group. The changes in airway volume, surface area, and linear values obtained from defined hard and soft tissue parameters were evaluated using preoperative and postoperative cone-beam computed tomography. A paired t-test was used to explore the statistical significance. RESULTS: A statistically significant increase in the airway volume (34.3%) was observed in the MMA group. The changes in the MAMS group were not statistically significant, although an average volumetric decrease of 8.8% was observed. The minimal axial surface area measurements in the MMA group at the levels of the soft palate and the tongue were significantly increased (56.8% and 44.9%, respectively). However, MAMS resulted in no significant changes at these levels (11.2% and 9.1% decrease, respectively). Linear changes showed a statistically significant increase in the airway in the MMA group, whereas the same measurements failed to produce significant changes in the MAMS group. CONCLUSION: As there were no significant changes in the measured parameters, surgeons can have greater confidence that MAMS does not have any negative influence on the airway.

Use of Intravenous Acetaminophen in Postoperative Pain Management After Partial and Full Bony Impacted Third Molar Extractions: A Randomized Double-Blind Controlled Trial.

PURPOSE: Currently, there is a concern at the national level of the overuse of both prescription and nonprescription opioid use. The purpose of this study was to identify whether the use of the intravenous (IV) formulation of acetaminophen (Ofirmev; Mallinckrodt Pharmaceuticals, Staines-upon-Thames, United Kingdom) is an effective tool in the reduction of postoperative pain, with a secondary goal of reduction of postoperative narcotic use. MATERIALS AND METHODS: A total of 72 patients with previously diagnosed either partial bony or complete bony impacted third molars were selected with care to avoid long-acting local anesthetics or dissociative anesthetic agents. The patients' postoperative pain scores at 4 and 24 hours were collected via a verbal rating scale by the primary investigator. The exclusion criteria included administration of bupivacaine or ketamine, hepatic or renal impairment, pregnancy, or allergy to any of the normally administered sedation medications. RESULTS: At all postoperative increments (immediately, 4 hours, and 24 hours), there was no significant difference at P < .05 between scores for either the IV acetaminophen or placebo group. Although there was a recorded difference in reduction of pain at both 4 and 24 hours postoperatively, these were not statistically significant variables. CONCLUSIONS: The use of IV acetaminophen showed no statistically significant decrease in patient pain at either 4 or 24 hours postoperatively. Although there are not representative data suggesting the routine use of IV acetaminophen, on the basis of the abundance of literature on the treatment of pain for other procedures, this medication should not be discarded as ineffective.

Does the Intake of Selective Serotonin Reuptake Inhibitors Negatively Affect Dental Implant Osseointegration? A Retrospective Study.

The success of osseointegration is influenced by several factors that affect bone metabolism and by certain systemic medications. Selective serotonin reuptake inhibitors (SSRIs) have been previously suggested to be among these medications. This study aims to investigate the association between systemic intake of SSRIs and failure of osseointegration in patients rehabilitated with dental implants. A retrospective cohort study was conducted, including a total of 2055 osseointegrated dental implants in 631 patients (109 implants in 36 SSRI \users and 1946 in 595 nonusers). Predictor and outcome variables were SSRI intake and osseointegration failure, respectively. The data were analyzed with Mann-Whitney test or Fisher exact test accordingly. Both patient-level and implant-level models were implemented to evaluate the effect of SSRI exposure on the success of osseointegration of dental implants. Median duration of follow-up was 21.5 months (range = 4-56 months) for SSRI users and 23 months (range -60 months) for nonusers ( P = .158). Two of 36 SSRI users had 1 failed implant each; thus, the failure rate was 5.6%. Eleven nonusers also had 1 failed implant each; thus, the failure rate was 1.85%. The difference between the 2 groups failed to reach statistical significance at patient and implant levels ( P = .166, P = .149, respectively). The odds of implant failure were 3.123 times greater for SSRI users compared with nonusers. Patients using SSRIs were found to be 3.005 times more likely to experience early implant failure than nonusers. The results of this study suggest that SSRIs may lead to increase in the rate of osseointegration failure, although not reaching statistical significance.

A finite element analysis of the stress distribution to the mandible from impact forces with various orientations of third molars.

OBJECTIVE: To investigate the stress distribution to the mandible, with and without impacted third molars (IM3s) at various orientations, resulting from a 2000-Newton impact force either from the anterior midline or from the body of the mandible. MATERIALS AND METHODS: A 3D mandibular virtual model from a healthy dentate patient was created and the mechanical properties of the mandible were categorized to 9 levels based on the Hounsfield unit measured from computed tomography (CT) images. Von Mises stress distributions to the mandibular angle and condylar areas from static impact forces (Load I-front blow and Load II left blow) were evaluated using finite element analysis (FEA). Six groups with IM3 were included: full horizontal bony, full vertical bony, full 450 mesioangular bony, partial horizontal bony, partial vertical, and partial 450 mesioangular bony impaction, and a baseline group with no third molars. RESULTS: Von Mises stresses in the condyle and angle areas were higher for partially than for fully impacted third molars under both loading conditions, with partial horizontal IM3 showing the highest fracture risk. Stresses were higher on the contralateral than on the ipsilateral side. Under Load II, the angle area had the highest stress for various orientations of IM3s. The condylar region had the highest stress when IM3s were absent. CONCLUSIONS: High-impact forces are more likely to cause condylar rather than angular fracture when IM3s are missing. The risk of mandibular fracture is higher for partially than fully impacted third molars, with the angulation of impaction having little effect on facture risk.

Comparative assessment of 3D reconstruction technique and Cavalieri's principle in predicting the mandibular bone defect volumes.

PURPOSE: The objective of this study was to compare the accuracy of the Cavalieri's principle and 3D reconstruction in predicting the volume of a bony defect. MATERIALS AND METHODS: Defects of the same approximate size were created on nine artificial mandibles. The actual volume of the defect on each mandible was measured by water displacement, and served as the control. Each mandible was then scanned using a CBCT and volume measurements were made for each defect using two techniques: Cavalieri's principle and 3D reconstruction. For each defect, the volume obtained by each of the two techniques was compared to the control volume using the analysis of variances (ANOVA) with p<0.05. RESULTS: ANOVA between the control, 3D reconstruction and Cavalieri's principle groups showed no statistically significant differences (p=.058). When the control group was further analyzed by Dunnett's post-hoc test, the results from Cavalieri's principle were found to be statistically different than the control group (p=.035), whereas the results of 3D reconstruction technique did not reach the level of significance (p=.523). CONCLUSION: Cavalieri's principle significantly underestimates the actual control volume, and is less accurate than the 3D reconstruction technique. The 3D reconstruction method is a reliable technique in measuring volume of bony defects.

Langerhans Cell Histiocytosis: A Diagnostic Challenge in the Oral Cavity.

BACKGROUND: Langerhans cell histiocytosis (LCH) is a rare disorder of the reticuloendothelial system with unknown etiology. This report aims to present a case of LCH with diffuse involvement of the oral cavity and to raise awareness of the distinguishing features of this diagnostically challenging entity. CASE REPORT: A 26-year-old male patient presented with complaints of teeth mobility, intense pain, and difficulty in chewing. Intraoral and radiological examinations revealed generalized gingival hyperplasia and severe teeth mobility with widespread alveolar bone loss. Periodontal therapy was performed with no significant improvement. An incisional biopsy revealed Langerhans cells and positive reaction to S-100 and CD1, and the patient was diagnosed with LCH. The patient underwent systemic chemotherapy with vinca alkaloids and corticosteroids. Regression of gingival lesions, as well as significant decrease in mobility of the remaining teeth and severity of pain, was achieved during 12 months of follow-up. CONCLUSION: The rarity and variable system involvement of LCH necessitate a multidisciplinary approach be carried out for accurate diagnosis, effective treatment, and an uneventful follow-up. Awareness of oral manifestations of LCH may aid clinicians greatly in reducing morbidity and mortality associated with this debilitating condition.

A customized fixation plate with novel structure designed by topological optimization for mandibular angle fracture based on finite element analysis.

BACKGROUND: The purpose of this study was to design a customized fixation plate for mandibular angle fracture using topological optimization based on the biomechanical properties of the two conventional fixation systems, and compare the results of stress, strain and displacement distributions calculated by finite element analysis (FEA). METHODS: A three-dimensional (3D) virtual mandible was reconstructed from CT images with a mimic angle fracture and a 1 mm gap between two bone segments, and then a FEA model, including volume mesh with inhomogeneous bone material properties, three loading conditions and constraints (muscles and condyles), was created to design a customized plate using topological optimization method, then the shape of the plate was referenced from the stress concentrated area on an initial part created from thickened bone surface for optimal calculation, and then the plate was formulated as "V" pattern according to dimensions of standard mini-plate finally. To compare the biomechanical behavior of the "V" plate and other conventional mini-plates for angle fracture fixation, two conventional fixation systems were used: type A, one standard mini-plate, and type B, two standard mini-plates, and the stress, strain and displacement distributions within the three fixation systems were compared and discussed. RESULTS: The stress, strain and displacement distributions to the angle fractured mandible with three different fixation modalities were collected, respectively, and the maximum stress for each model emerged at the mandibular ramus or screw holes. Under the same loading conditions, the maximum stress on the customized fixation system decreased 74.3, 75.6 and 70.6% compared to type A, and 34.9, 34.1, and 39.6% compared to type B. All maximum von Mises stresses of mandible were well below the allowable stress of human bone, as well as maximum principal strain. And the displacement diagram of bony segments indicated the effect of treatment with different fixation systems. CONCLUSIONS: The customized fixation system with topological optimized structure has good biomechanical behavior for mandibular angle fracture because the stress, strain and displacement within the plate could be reduced significantly comparing to conventional "one mini-plate" or "two mini-plates" systems. The design methodology for customized fixation system could be used for other fractures in mandible or other bones to acquire better mechanical behavior of the system and improve stable environment for bone healing. And together with SLM, the customized plate with optimal structure could be designed and fabricated rapidly to satisfy the urgent time requirements for treatment.

Clinical relevance of the utilization of vital Lugol's iodine staining in detection and diagnosis of oral cancer and dysplasia.

OBJECTIVES: The aim of this study is to assess the clinical relevance of the utilization of vital Lugol's iodine staining in detection of oral cancer and dysplastic lesions as well as demarcation of the extent of these lesions. MATERIALS AND METHODS: A prospective, cross-sectional, hospital-based study was performed in Khartoum Teaching Dental Hospital, Sudan. Suspicious oral epithelial lesions indicating incisional biopsy were stained with 10 % Lugol's iodine solution and were clinically designated as "negative" for dysplasia or neoplasia when no unstained lesion (USL) area was observed, or as "positive" when a USL area is observed. Incisional biopsies involving both the unstained portion and the stained portion were obtained and histologically evaluated for definitive diagnosis. RESULTS: Forty-five biopsies were obtained from 28 patients. Histopathological examination of the specimens confirmed some degree of dysplasia or neoplasia in all clinically positive specimens with oral squamous cell carcinoma (OSCC) being the most common definitive diagnosis (17 patients, 60.7 %). Clinical relevance level of vital Lugol's iodine staining in detecting oral cancer and dysplasia was found to be 90.9 % (SE = 0.05, P = 0.05). CONCLUSION: The findings of this study showed that Lugol's iodine is an easy, safe, and effective method of visualizing oral epithelial lesions and differentiating epithelial carcinoma and dysplasia from other benign mucosal lesions. Despite certain limitations, its use is of great value in detection and diagnosis of oral cancer and dysplasia. CLINICAL RELEVANCE: Lugol's iodine staining can effectively be used in detection of the dysplastic and malignant superficial lesions of the oral epithelium.

Transconjunctival Lower Blepharoplasty.

There is no secret to achieving successful results with lower belpharoplasties; as is the case with any surgical procedure, proper patient evaluation and development of a comprehensive, anatomic-based treatment plan are prerequisites for success. For situations in which a patient has little lid laxity and pseudoherniated periorbital fat, transconjunctival lower blepharoplasty is the treatment of choice. Transconjunctival lower blepharoplasty enables the surgeon to reposition fat, effectively blending the lid-cheek junction and filling the tear trough deformity. In order to better enable clinicians to achieve optimal outcomes, the authors advocate an anatomic-based approach for patient evaluation and treatment planning.