OBJECTIVETo assess the application of three-dimensional jaw model in treatment of superolateral dislocation of condyle.

METHODSNine patients with superolateral dislocation of condyle and symphyseal fractures were admitted in hospital from June 2008 to June 2013. Spiral CT scan on maxilla and mandible was performed，and three-dimensional jaw model was constructed with rapid prototyping technology. According to conditions of condylar superolateral dislocation model，the operation scheme was designed. The symphyseal fracture line was made and fracture was reduced on three-dimensional jaw model. Individualized prefabricated reconstructive titanium plate was made on symphyseal fracture model. Symphyseal fracture was replaced with individualized prefabricated mandibular reconstruction titanium plate according to occlusal relationship. At the same time，reduction of condylar superolateral dislocation was accomplished.

RESULTSOperations were successfully completed in 9 cases under guidance of three dimensional jaw model surgery. Operative incision was primarily healed，and occlusal relationship was restored. Postoperative CT scan showed that the locations of condyle in 9 cases were completely restored. Patients were followed-up for 6-28 months with a median of 18 months. The maximum of mouth opening was 3.1- 4.2 cm with a medians of 3.3 cm，and the occlusal relationship of all patients was normal after surgery.

CONCLUSIONThree-dimensional jaw model can show complete status of condylar superolateral dislocation and symphyseal fracture. The model can accurately shape symphyseal reconstructive titanium plate and restore condylar superolateral dislocation during reductive surgery.

Humans ; Joint Dislocations ; Mandibular Condyle ; physiopathology ; surgery ; Mandibular Fractures ; surgery ; Models, Anatomic ; Tomography, Spiral Computed ; Tomography, X-Ray Computed

OBJECTIVETo explore the biomechanical mechanism of impact force-induced mandibular fractures and its finite element analysis.

METHODSThree mandibular impact fracture models were prepared using intact human mandibular specimens and simulated maxillary models according to the Hanau principle of articulator and a MTS-858 biological material testing machine. Mandibular impact was delivered in the direction of the chin level at the mandibular postural position (MPP) on MTS. The computerized mandibular model was then established from 3-dimensional laser scanning images for finite element analysis using ANSYS7.0.

RESULTSThe 3 mandibular specimens were fractured at the chin, where the maximum force was 2151.10-/+ 125.18 N with response time of 17.3-/+2.3 ms. Impact simulation with ANSYS mimicking stress changes in the internal jaw suggested the chin as place where maximum stress occurred. According to the stress curve, the maximum stress of 3201.35 kPa occurred at the point 1.92 cm from the upper edge of the chin.

CONCLUSIONThe combination of mandibular impact experiments and finite element analysis allows quantification of several parameters of the jaw and provides clues for understanding the biomechanical mechanism of mandibular impact fractures.

Biomechanical Phenomena ; Finite Element Analysis ; Humans ; Mandible ; pathology ; physiopathology ; Mandibular Fractures ; physiopathology ; Models, Anatomic ; Stress, Mechanical ; Tensile Strength

OBJECTIVETo investigate the effect of recombinant human basic fibroblast growth factor (rhbFGF) on angiogenesis during mandible fracture healing in rabbit.

METHODSFifty adult white rabbits were used for animal model and randomly divided into a control group (25 rabbits) and an experimental group (25 rabbits). The membranous complex of rhbFGF and bovine type I collagen was prepared and implanted into the rabbit mandible fracture site under periosteum. The animals were sacrificed on 7, 14, 28, 56 and 84 days respectively after operation and the whole mandibles were harvested. The expression of factor VIII related antigen (F8-RA) in callus was examined with immunohistochemical staining.

RESULTSThe amounts of microvascular formation in calluses in the rhbFGF-treating group on days 7, 14, 28 and 56 were more than those of the control group (P<0.01).

CONCLUSIONSThe results indicated that rhbFGF could stimulate microvascular formation during mandible fracture healing in rabbits.

Animals ; Fibroblast Growth Factor 2 ; pharmacology ; Fracture Healing ; physiology ; Mandibular Fractures ; physiopathology ; Neovascularization, Physiologic ; drug effects ; Rabbits ; Recombinant Proteins ; pharmacology

Biodynamics of mandibular angle fractures has been extensively discussed in the literature in search for the best way to fixate and expedite recovery of trauma patients. Pioneers like Michelet and Champy had the greatest impact on evolving of osteosynthesis in maxillofacial traumatology; they introduced their basic principles frequently used to describe the biomechanics of mandibular fixation. Their concept states when a physiologic load is applied on mandibular teeth a negative tension will be created at superior border and a positive pressure will appear at inferior border. These simple definitions are the basis for the advent of fixation modalities in mandibular angle fracture. This article sought to reassess these principals based on load location via finite elements method.
Biomechanical Phenomena ; Dental Stress Analysis ; Finite Element Analysis ; Fracture Fixation, Internal ; methods ; Humans ; Mandible ; physiopathology ; Mandibular Fractures ; physiopathology ; surgery ; Tooth ; physiology

OBJECTIVETo study the expression of dentin matrix protein 1 (DMP1) and osteoclast in callus at different healing period of mandibular fracture in a adult Wistar rat model.

METHODSThe mandibular fracture model of Wistar rats at the left mandibular ramus was established. The callus in the fractured site and the normal mandible were amputated at the 5th, 7th, 14th and 21st day after the fracture. HE staining was used to observe the condition of fracture healing and TRAP staining used to observe the activation of osteoclast. The expression of DMP1 was detected in the callus by using immunohistochemical method.

RESULTSThe number of osteoclasts reached a peak from the 14th to 21st day. The expression of DMP1 became very active from the 7th to 14th day.

CONCLUSIONSThe expression of DMP1 and osteoclast during fracture healing exhibited time effect.

Animals ; Disease Models, Animal ; Extracellular Matrix Proteins ; metabolism ; Fracture Healing ; physiology ; Mandible ; metabolism ; Mandibular Fractures ; metabolism ; physiopathology ; Osteoclasts ; physiology ; Phosphoproteins ; metabolism ; Rats ; Rats, Wistar

PURPOSE: The purpose of the study is to compare the surgical access and post-operative outcome of two intra-oral incisions used for approaching a mandibular body fracture. METHODS: This clinical trial involved 60 patients with mandibular body fractures who were randomly allocated to control and study groups. The fractures were approached using the routine vestibular incision in the control group and crevicular incision with vertical release in the study group. The effects of incision design on the post-surgical outcome variables like swelling, trismus, paresthesia, wound healing and gingival recession were statistically analysed with non-parametric tests by using SPSS 22.0 software. Comparison of continuous variables between the groups and time points was done using Mann Whitney test and Friedman test respectively. Chi-square test was used to compare proportions between groups. Dunn's test with Bonferroni correction was used for pair wise comparisons. RESULTS: The study group demonstrated favourable surgical outcome in the immediate postoperative phase as compared to the control group. The difference in mouth opening, swelling and neurosensory impairment between the two groups was found to be statistically significant (p < 0.05). CONCLUSION Crevicular incision was found to be an ideal alternative to vestibular incision in achieving surgical access and fixation of mandibular body fractures with reduction in postoperative patient discomfort and better surgical outcome.
Adult ; Female ; Fracture Fixation, Internal ; methods ; Humans ; Male ; Mandibular Fractures ; physiopathology ; surgery ; Middle Aged ; Open Fracture Reduction ; methods ; Orthognathic Surgical Procedures ; methods ; Surgical Wound ; Treatment Outcome ; Young Adult

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.
Adult ; Algorithms ; Biomechanical Phenomena ; Computer Simulation ; Dental Stress Analysis ; Elastic Modulus ; Female ; Finite Element Analysis ; Humans ; Imaging, Three-Dimensional ; Mandible/physiopathology* ; Mandibular Fractures/physiopathology* ; Models, Biological ; Molar, Third/physiopathology* ; Stress, Mechanical ; Tomography, X-Ray Computed

OBJECTIVETo observe mandibular fracture healing after synthesized bioabsorable poly-para-dioxanone (PDS) ligature fixation.

METHODSPara-dioxanone monomer was prepared by chemical reactions of metallic sodium, ethylene glycol and other raw materials. PDS was synthesized by polymerizing the purified para-dioxanone in the presence of catalyst under the conditions of negative pressure and certain temperature. PDS ligature was obtained by processing the polymer into small granules, drying and melt-extruding through a spinnerette. Eighteen adult male New Zealand rabbits were assigned randomly into two groups. After mandibular fracture models were created, reductions of the artificial fractures were accomplished by means of transosseous PDS ligatures on each of 12 rabbits in experimental group. While the other six rabbits without any internal fixation were set as control. Schedules for killing were arranged to give postoperative samples at two-week interval till 12th week.

RESULTSRadiographical and histological examinations demonstrated that all fractures fixed with PDS ligatures healed without any complication. Periosteal and cartilaginous osteogenesis was observed in newly formed external callus. In contrast, bone fragment migration and the consequent nonunion occurred in the control group. PDS ligature degraded and absorbed without interference with osseous union and healing. The tensile strength reduction of PDS ligature was prior to its absorption in vivo.

CONCLUSIONThe synthesized PDS is a colorless, flexible, themoplastic and monofilament fiber, which can be sterilized by ethylene oxide embalmment without serious loss of tensile strength. It seems that the application of this macromolecular material in internal fixation is of great worth for further study.

Absorbable Implants ; Animals ; Biodegradation, Environmental ; Bone Regeneration ; drug effects ; Fracture Fixation, Internal ; instrumentation ; methods ; Fracture Healing ; Male ; Mandibular Fractures ; physiopathology ; surgery ; Materials Testing ; Polydioxanone ; administration & dosage ; chemical synthesis ; Rabbits ; Random Allocation ; Tensile Strength