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Bioengineering (Basel, Switzerland) Mar 2024Mandibular fractures are very common in maxillofacial trauma surgery. While previous studies have focused on possible risk factors related to post-operative...
Mandibular fractures are very common in maxillofacial trauma surgery. While previous studies have focused on possible risk factors related to post-operative complications, none have tried to identify pre-existing conditions that may increase the risk of mandibular fractures. We hypothesized, through clinical observation, that anatomical conditions involving poor dental contacts, such as malocclusions, may increase the risk of mandibular fractures. This work was subdivided into two parts. In the first part, Digital Imaging and Communications in Medicine (DICOM) data of four healthy patients characterized by different dentoskeletal occlusions (class I, class II, class III, and anterior open bite) have been used to develop four finite element models (FEMs) that accurately reproduce human bone structure. A vertical and lateral impact have been simulated at increasing speed on each model, analyzing the force distribution within the mandibular bone. Both vertical and lateral impact showed higher level of stress at the impact point and in the condylar area in models characterized by malocclusion. Specifically, the class III and the open bite models, at the same speed of impact, had higher values for a longer period, reaching critical stress levels that are correlated with mandibular fracture, while normal occlusion seems to be a protective condition. In the second part of this study, the engineering results were validated through the comparison with a sample of patients previously treated for mandibular fracture. Data from 223 mandibular fractures, due to low-energy injuries, were retrospectively collected to evaluate a possible correlation between pre-existing malocclusion and fracture patterns, considering grade of displacement, numbers of foci, and associated CFI score. Patients were classified, according to their occlusion, into Class I, Class II, Class III, and anterior open bite or poor occlusal contact (POC). Class I patients showed lower frequencies of fracture than class II, III, and open bite or POC patients. Class I was associated with displaced fractures in 16.1% of cases, class II in 47.1%, class III in 48.8% and open bite/POC in 65.2% of cases (-value < 0.0001). In class I patients we observed a single non-displaced fracture in 51.6% of cases, compared to 12.9% of Class II, 19.5% of Class III and 22.7% of the open bite/POC group. Our analysis shows that class I appears to better dissipate forces applied on the mandible in low-energy injuries. A higher number of dental contacts showed a lower rate of multifocal and displaced fractures, mitigating the effect of direct forces onto the bone. The correlation between clinical data and virtual simulation on FEM models seems to point out that virtual simulation successfully predicts fracture patterns and risk of association with different type of occlusion. Better knowledge of biomechanics and force dissipation on the human body may lead to the development of more effective safety devices, and help select patients to plan medical, orthodontic/dental, and/or surgical intervention to prevent injuries.
PubMed: 38534548
DOI: 10.3390/bioengineering11030274 -
Dental Research Journal 2023Horizontal condylar guidance (HCG) is registered by protrusive interocclusal records but in nonarcon articulators, these records can affect the accuracy. The present...
BACKGROUND
Horizontal condylar guidance (HCG) is registered by protrusive interocclusal records but in nonarcon articulators, these records can affect the accuracy. The present study aimed to evaluate the effect of a novel rotation coordinating device (RCD) on condylar guidance setting with protrusive interocclusal records.
MATERIALS AND METHODS
The study was designed as a comparative investigation. Stone maxillary and mandibular casts were mounted on a fully adjustable instrument as the patient. Duplicate casts were mounted on an arcon and a nonarcon articulator with corresponding face bow records and in maximum intercuspation relation. Five different condylar guidance inclinations for both sides (20°, 30°, 40°, 50°, and 60°) were set on the fully adjustable instrument and 16 protrusive interocclusal records were established at each setting. HCG was set for arcon, nonarcon articulators, and nonarcon articulators with RCD. Data were analyzed using one-sample -test to compare with actual HCG and one-way analysis of variance ( =0.05).
RESULTS
Mean HCG for studied articulators was 35.40 for arcon, 30.31 for nonarcon without RCD, and 35.61 for nonarcon with RCD which were significantly different from actual HCG ( < 0.05). HCG of the nonarcon with RCD showed no significant difference with arcon articulator ( = 0.71) while both were significantly different from nonarcon without RCD ( < 0.001).
CONCLUSION
"The RCD" compensates the condylar guidance inclination difference between arcon and nonarcon articulators. The device precisely transfers the hinge movement of the upper member of the articulator to the condylar track.
PubMed: 38020259
DOI: No ID Found -
PeerJ 2024Assessing the relationship between the condyle and mandible volume and the various skeletal classes is essential in orthodontic diagnosis. The current study evaluated...
BACKGROUND
Assessing the relationship between the condyle and mandible volume and the various skeletal classes is essential in orthodontic diagnosis. The current study evaluated this relationship using volumetric cone-beam computed tomography (CBCT), cephalometric methods, and the correlations between them.
MATERIALS AND METHODS
The study examined 37 full-head CBCTs (74 condyles) from adults in the Saudi population. The condyle and mandible were separated from within the CBCT images. The volume of each segment was compared to measurements from multiple cephalometric analyses.
RESULTS
The combined total condylar volume has a moderate correlation with the maxillomandibular differential in each of the genders and in the total sample. Mandibular volume has a significant correlation with the Wits appraisal (sagittal classification) in males. It was also significantly correlated with the vertical classification using gonial angles in females and in the total sample.
CONCLUSION
The relationship between mandible and condyle volume and cephalometric measurements is both dimensional and within the maxillomandibular complex rather than positional or related to the cranial base. Also, the correlation between the condylar and mandibular volumes and the sagittal and vertical dimensions in the orthodontic skeletal classes provides better insight into the mandibular complex.
Topics: Adult; Humans; Female; Male; Mandibular Condyle; Saudi Arabia; Mandible; Cephalometry; Cone-Beam Computed Tomography
PubMed: 38188155
DOI: 10.7717/peerj.16750 -
BMC Oral Health May 2024Extracellular matrix (ECM) protein malfunction or defect may lead to temporomandibular joint osteoarthritis (TMJ OA). Dentin sialophophoprotein (DSPP) is a mandibular...
BACKGROUND
Extracellular matrix (ECM) protein malfunction or defect may lead to temporomandibular joint osteoarthritis (TMJ OA). Dentin sialophophoprotein (DSPP) is a mandibular condylar cartilage ECM protein, and its deletion impacted cell proliferation and other extracellular matrix alterations of postnatal condylar cartilage. However, it remains unclear if long-term loss of function of DSPP leads to TMJ OA. The study aimed to test the hypothesis that long-term haploinsufficiency of DSPP causes TMJ OA.
MATERIALS AND METHODS
To determine whether Dspp mice exhibit TMJ OA but no severe tooth defects, mandibles of wild-type (WT), Dspp, and Dspp homozygous (Dspp) mice were analyzed by Micro-computed tomography (micro-CT). To characterize the progression and possible mechanisms of osteoarthritic degeneration over time in Dspp mice over time, condyles of Dspp and WT mice were analyzed radiologically, histologically, and immunohistochemically.
RESULTS
Micro-CT and histomorphometric analyses revealed that Dspp and Dspp mice had significantly lower subchondral bone mass, bone volume fraction, bone mineral density, and trabecular thickness compared to WT mice at 12 months. Interestingly, in contrast to Dspp mice which exhibited tooth loss, Dspp mice had minor tooth defects. RNA sequencing data showed that haplodeficency of DSPP affects the biological process of ossification and osteoclast differentiation. Additionally, histological analysis showed that Dspp mice had condylar cartilage fissures, reduced cartilage thickness, decreased articular cell numbers and severe subchondral bone cavities, and with signs that were exaggerated with age. Radiographic data showed an increase in subchondral osteoporosis up to 18 months and osteophyte formation at 21 months. Moreover, Dspp mice showed increased distribution of osteoclasts in the subchondral bone and increased expression of MMP2, IL-6, FN-1, and TLR4 in the mandibular condylar cartilage.
CONCLUSIONS
Dspp mice exhibit TMJ OA in a time-dependent manner, with lesions in the mandibular condyle attributed to hypomineralization of subchondral bone and breakdown of the mandibular condylar cartilage, accompanied by upregulation of inflammatory markers.
Topics: Animals; Osteoarthritis; Mice; X-Ray Microtomography; Sialoglycoproteins; Extracellular Matrix Proteins; Temporomandibular Joint Disorders; Phosphoproteins; Mandibular Condyle; Temporomandibular Joint
PubMed: 38745274
DOI: 10.1186/s12903-024-04320-8 -
A new classification of mandible defects and condyle changed after mandible reconstruction with FFF.Heliyon Feb 2024To explore a new classification of mandibular defects and changes in the preserved condyle after mandibular reconstruction with free fibular flap(FFF).
OBJECTIVES
To explore a new classification of mandibular defects and changes in the preserved condyle after mandibular reconstruction with free fibular flap(FFF).
STUDY DESIGN
We reviewed patients who underwent mandibular reconstruction with FFF from 2015 to 2021 and classified the mandibular defects into five categories: classⅠ(unilateral-mandibular excluding condyle), classⅡ(unilateral-mandibular including condyle), classⅢ(bilateral-mandibular excluding condyle), classⅣ(bilateral-mandibular including one condyle), and classⅤ(bilateral-mandibular including both condyles). Cone Beam Computed Tomography (CBCT) data were collected preoperatively(T0), at 7-10 postoperative days(T1), 6 postoperative months(T2), and 1 postoperative year(T3). We calculated the condylar surface area, volume, and displacement.
RESULTS
62 cases were collected. The condylar surface areas and volumes in T2 and T3 values were lower than those of T0 and T1(P < 0.01) The condylar displacement was the lowest in ClassI and the largest in ClassⅣ(P < 0.01), while no significant differences in classesⅠ-Ⅲ(P < 0.05). Displacement during T1-T0 was greater than that during T2-T0 and T3-T0(P < 0.05).
CONCLUSION
Mandibular reconstruction with FFF results in displacement and alteration of the condyle within a time interval, and this alteration stabilizes after 6 months. Mandibular defects that do not reach the midline, surgical alteration to preserve the condyle are not required. However, when the defects cross the midline, the condyle should be preserved as much as possible.
PubMed: 38384523
DOI: 10.1016/j.heliyon.2024.e25831 -
A retrospective study on application of fibula/iliac flap surgical techniques to mandibular defects.Scientific Reports Oct 2023This study group consists of a total of 61 patients who underwent fibula flap and iliac flap surgeries to repair mandibular defects. Patients' Quality Of life (QOL) at 6...
This study group consists of a total of 61 patients who underwent fibula flap and iliac flap surgeries to repair mandibular defects. Patients' Quality Of life (QOL) at 6 and 24 months after surgery is investigated and compared by the EORTC-QLQ-H&N and OHIP-14. The base data of the two groups of patients are collected and analysed by the SPSS 20.0 statistical software. Independent sample t test was conducted for EORTC-QLQ-H&N and OHIP-14 scores at two time points in each group. The 61 cases of free flap all survived and the difference in the location of the primary tumor between the two groups is statistically significant. The EORTC-QLQ-H&N showed that the score of speech, diet, social contact, and teeth all went up at 6 months after surgery, but went down dramatically at 24 months after surgery. The OHIP-14 showed that there was significant reduction in functional limitation at 24 months after surgery, with statistical significance (p < 0.05) between the groups of iliac flap (19.16 ± 5.33) and fibula flap (33.77 ± 7.71). Therefore, it is suggested that patients suffering from mandibular defects receive surgery utilizing the iliac flap, while those with a larger range of defects or lesions involving the condyle and chin should receive corrective surgery utilizing the fibular flap.
Topics: Humans; Retrospective Studies; Quality of Life; Fibula; Mandible; Free Tissue Flaps; Bone Transplantation
PubMed: 37783776
DOI: 10.1038/s41598-023-43643-4 -
Zhongguo Xiu Fu Chong Jian Wai Ke Za... Oct 2023To preliminarily verify the effectiveness of self-designed artificial condyle-mandibular distraction (AC-MD) complex in the treatment of Pruzansky type ⅡB and Ⅲ...
OBJECTIVE
To preliminarily verify the effectiveness of self-designed artificial condyle-mandibular distraction (AC-MD) complex in the treatment of Pruzansky type ⅡB and Ⅲ hemifacial microsomia (HFM) through model test.
METHODS
Five children with Pruzansky type ⅡB and Ⅲ HFM who were treated with mandibular distraction osteogenesis (MDO) between December 2016 and December 2021 were selected as the subjects. There were 3 boys and 2 girls wih an average age of 8.4 years (range, 6-10 years). Virtual surgery and model test of AC-MD complex were performed according to preoperative skull CT of children. The model was obtained by three-dimensional (3D) printing according to the children's CT data at a ratio of 1∶1. The occlusal guide plate was designed and 3D printed according to the children's toothpaste model. The results of the model test and the virtual surgery were matched in three dimensions to calculate the error of the residual condyle on the affected side, and the model test was matched with the actual skull CT after MDO to measure and compare the inclination rotation of the mandible, the distance between the condylar of the healthy side and the residual condyle of the affected side, and the lengthening length of the mandible.
RESULTS
The error of residual condyle was (1.07±0.78) mm. The inclination rotation of the mandible, the distance between the condylar of the healthy side and the residual condyle of the affected side, and the lengthening length of the mandible after 3D printing model test were significantly larger than those after MDO ( <0.05).
CONCLUSION
In the model test, the implantation of AC-MD complex can immediately rotate the mandible to the horizontal position and improve facial symmetry, and the residual condyle segment can be guided close to the articular fossa or the preset pseudoarticular position of the skull base after operation.
Topics: Male; Child; Female; Humans; Goldenhar Syndrome; Mandible; Osteogenesis, Distraction; Printing, Three-Dimensional; Facial Asymmetry
PubMed: 37848324
DOI: 10.7507/1002-1892.202306022 -
Clinical Oral Investigations Jan 2024Among the existing techniques for the correction of mandibular posterior vertical insufficiency (PVI), the intra-oral ramus vertical lengthening osteotomy (IORVLO) can...
OBJECTIVES
Among the existing techniques for the correction of mandibular posterior vertical insufficiency (PVI), the intra-oral ramus vertical lengthening osteotomy (IORVLO) can be proposed as it allows simultaneous correction of mandibular height and retrusion. This study assessed the 3D morpho-anatomical changes of the ramus-condyle unit and occlusal stability after IORVLO.
MATERIALS AND METHODS
This retrospective analysis compared immediate and 1-year post-operative 3D CBCT reconstructions. The analysis focused on the condylar height (primary endpoint) and on the changes in condylar (condylar diameter, condylar axis angle) and mandibular (ramus height, Frankfort-mandibular plane angle, gonion position, intergonial distance, angular remodeling) parameters. Additionally, this analysis investigated the maxillary markers and occlusal stability.
RESULTS
On the 38 condyles studied in 21 included patients (mean age 23.7 ± 3.9 years), a condylar height (CH) loss of 0.66 mm (p < 0,03) was observed, with no correlation with the degree of ramus lengthening (mean 13.3 ± 0.76 mm). Only one patient presented an occlusal relapse of Class II, but a 3.4 mm (28%) condylar diameter loss and a 33% condylar volume reduction with loss of 1 mm and 3.4 mm in CH and condyle diameter, respectively. A mean 3.56 mm (p < 0.001) decrease in ramus height was noted, mainly due to bone resorption in the mandibular angles.
CONCLUSION
This study confirms the overall stability obtained with IORVLO for the correction of PVI.
CLINICAL RELEVANCE
This study aims to precise indication of IORVLO, and to validate the clinical and anatomical stability of results.
Topics: Humans; Young Adult; Adult; Retrospective Studies; Osteotomy; Plastic Surgery Procedures; Bone Resorption; Mandible; Polymers
PubMed: 38267793
DOI: 10.1007/s00784-024-05504-w -
Diagnostics (Basel, Switzerland) May 2024Unilateral condylar hyperplasia (UCH) is a rare cause of asymmetrical mandibular overgrowth because of the presence of an atypical growth in the affected condyle. SPECT...
Unilateral condylar hyperplasia (UCH) is a rare cause of asymmetrical mandibular overgrowth because of the presence of an atypical growth in the affected condyle. SPECT (single-photon emission computed tomography) can easily establish the presence of an atypical, prolonged growth exceeding far beyond normal condylar growth and activity. A CT, CBCT, or LDCT (computed tomography, cone-beam computed tomography, or low-dose computed tomography) can confirm the diagnosis by evaluating the scope of bone overgrowth, mandibular basis/ramus asymmetry, tendency to condylar head enlargement, changes in bone density, and occurrence of differences in condylar head shapes, size, and bone structure. In most cases, a condylectomy is the procedure of choice in growing cases of UCH to remove the pathological condyle and reduce asymmetry levels. Sometimes, the growth is very slow and progressive over time, causing slowly growing asymmetry with similar symptoms to any other mandibular asymmetry, and this causes some troublesome procedures in UCH diagnostics, resulting in patients being underdiagnosed; it can even lead to some relapses in mandibular asymmetry and skeletal malocclusion after previously performed orthodontic and surgical treatment of such discrepancies. When the source of asymmetry is not identified in time, possible inadequate treatment protocols can be used. If any relapse of facial and mandibular asymmetry re-occur, SPECT and CT evaluation are necessary to evaluate if condylar hyperplasia is present and to establish what kind of surgical intervention should be used in each case.
PubMed: 38786312
DOI: 10.3390/diagnostics14101014 -
Frontiers in Bioengineering and... 2023This study presents an innovative articular fossa prosthesis generated by the envelope surface of condyle movement, and compares its mandible movements, muscle...
This study presents an innovative articular fossa prosthesis generated by the envelope surface of condyle movement, and compares its mandible movements, muscle activities, and joint reaction forces with two temporomandibular joint (TMJ) prostheses using multibody musculoskeletal simulation. A healthy 23-year-old female was recruited for this study. Cone-beam computed tomographic (CBCT) was performed to reconstruct the mandibular bone geometry. A customized TMJ fossa prosthesis was designed based on the subject-specific envelope surface of condyle movement (ESCM). Mandibular kinematics and jaw-closing muscle electromyography (EMG) were simultaneously recorded during maximum jaw opening-closing movements. To validate our prosthesis design, a mandibular musculoskeletal model was established using flexible multibody dynamics and the obtained kinematics and EMG data. The Biomet fossa prosthesis and the ellipsoidal fossa prosthesis designed by imitating the lower limb prostheses were used for comparison. Simulations were performed to analyze the effects of different fossa prostheses on jaw opening-closing motions, mandibular muscle activation, and contact forces. The maximum opening displacement for the envelope-based fossa prosthesis was greater than those for Biomet and ellipsoidal prostheses (36 mm, 35 mm, and 33 mm, respectively). The mandibular musculoskeletal model with ellipsoidal prosthesis led to dislocation near maximal jaw opening. Compared to Biomet, the envelope-based fossa reduced the digastric and lateral pterygoid activation at maximal jaw opening. It also reduced the maximal resistance to condylar sliding on the intact side by 63.2 N. A customized TMJ fossa prosthesis was successfully developed using the ESCM concept. Our study of musculoskeletal multibody modeling has highlighted its advantages and potential. The artificial fossa design successfully achieved a wider condylar range of motion. It also reduced the activation of jaw opening muscles on the affected side and resistance on the intact side. This study showed that an ESCM-based approach may be useful for optimizing TMJ fossa prostheses design.
PubMed: 38026896
DOI: 10.3389/fbioe.2023.1273263