Effect of the interaction between periodontitis and type 1 diabetes mellitus on alveolar bone,mandibular condyle and tibia

Objective. This study examined the effect of the interaction between periodontitis and type 1 diabetes mellitus on alveolar bone, mandibular condyle and tibia in animal models. Materials and methods. Rats were divided into normal, periodontitis, diabetic and diabetic with periodontitis groups. After injection of streptozotocin to induce diabetes, periodontitis was induced by ligation of both lower-side first molars for 30 days. Alveolar bone loss and trabecular bone volume fraction (BVF) of the mandibular condyle and tibia were estimated via hematoxylin and eosin staining and micro-computed tomography, respectively. Osteoclastogenesis of bone marrow cells isolated from tibia and femur was assayed using tartrate-resistant acid phosphatase staining. Results. The cemento-enamel junction to the alveolar bone crest distance and ratio of periodontal ligament area in the diabetic with periodontitis group were significantly increased compared to those of the periodontitis group. Mandibular condyle BVF did not differ among groups. The BVF of tibia in the diabetic and diabetic with periodontitis groups was lower than that of the normal and periodontitis groups. Osteoclastogenesis of bone marrow cells in the diabetic groups was higher than that in the non-diabetic groups. However, the BVF of tibia and osteoclastogenesis in the diabetic with periodontitis group were not significantly different than those in the diabetic group. Conclusions. Type 1 diabetes mellitus aggravates alveolar bone loss induced by periodontitis, but periodontitis does not alter the mandibular condyle and tibia bone loss induced by diabetes. Alveolar bone, mandibular condyle and tibia may have different responses to bone loss stimuli in the diabetic environment.     

Local administration of IGF-I stimulates the growth of mandibular condyle in mature rats

Abstract

Aim: To evaluate the effects of local injection of insulin-like growth factor I (IGF-I) on the growth of mandibular condyle in mature rats.

Materials and methods: Sixteen 15 week-old male rats were used in this study. In the experimental group, IGF-I at a concentration of 50 μg/ml was injected into articular capsules of the condyle, while rats in the control group were injected with equal volume of physiological saline. These injections were performed three times at 7 day intervals, and all of the rats were killed on the 7th day after the last injection. Tetracycline and calcein were used for vital staining. After death, the condyles were extracted and undecalcified ground sections were prepared for histological and histomorphometric observations. The thickness of the cartilaginous layer of the condyle, the percentage of bone area in the subchondral cancellous bone layer and the amount of endochondral bone growth in the condyle were measured. The significance of the difference in these measurements between IGF-I and control group was evaluated.

Results: An increase in the thickness of the cartilaginous layer, and a decrease in the percentage of bone area in the subchondral cancellous bone layer was recognized in IGF-I treated condyle. The amount of endochondral bone growth in the experimental group was greater than that in the control group.

Conclusion: The local injection of IGF-I into mature condyle seemed to reactivate the process of endochondral bone formation and induced actual bone growth in mature condyle.     

Cone beam computed tomographic assessment of mandibular condyle in Kennedy class I patients

Objectives

The aim of this study was to assess the dimensional and volumetric changes in the mandibular condyle in Kennedy class I patients versus completely dentate patients by cone beam computed tomography (CBCT) to estimate the effect of loss of posterior teeth on the mandibular condyle.

Patients and methods

This study was performed on one hundred patients requesting CBCT scans: fifty Kennedy class I patients and fifty fully dentate controls. Condyle dimensions mesio-distal, cranio-caudal and antero-posterior as well as condyle volume were measured in both the groups.

Results

Kennedy class I patients showed statistically significant higher mean condyle width but lower mean condyle height than the control group. No statistically significant difference was found between the study group and the control group regarding condyle AP dimension. There was no statistically significant difference between condyle volumes in the two groups.

Conclusion

Loss of posterior teeth is accompanied by significant decrease in condyle height and increase in condyle width with no change in the total condyle volume or antero-posterior dimensions.

     

Morphometric analysis of the mandibular fossa in dentate and edentulous patients: A cone beam computed tomography study

Statement of problemMandibular fossa roof thickness and lateral inclination could be associated with the presence of bone changes in the mandibular condyle in dentate and edentulous patients. However, literature regarding the relationship between the presence and absence of teeth and the morphologic features of the temporomandibular joint is lacking. This knowledge could provide a better understanding of changes affecting the correct functioning of the stomatognathic system.PurposeThe purpose of this clinical study was to assess the mandibular fossa roof thickness and lateral inclination in relation to sex, presence or absence of teeth, and bone changes in the mandibular condyle through cone beam computed tomography (CBCT).Material and methodsCBCT scans of 100 individuals (50 dentate and 50 edentulous) were evaluated in terms of mandibular fossa roof thickness and lateral inclination. Bone changes in the mandibular condyle were classified dichotomously in relation to osteophytes, erosion, sclerosis, and flattening. Differences were assessed with the Student t test, the chi-square test, and 2-way analysis of variance (ANOVA), with Tukey post hoc tests (α=.05).ResultsSex was not related to mandibular fossa measurements. Edentulous participants showed a higher mandibular fossa lateral inclination (P<.001) and lower roof thickness (P=.001) than dentate participants. When the association between bone changes in the mandibular condyle was evaluated in dentate and edentulous groups, only sclerosis showed a statistically significant association (P<.001). The 2-way ANOVA showed that the mandibular fossa roof thickness was lower in edentulous participants in the presence of flattening and erosion and that the mandibular fossa lateral inclination was higher in the presence of osteophytes, erosion, and sclerosis (P<.001). Among dentate participants, the mandibular fossa lateral inclination was higher in the presence of flattening (P=.024).ConclusionsMandibular fossa roof thickness and lateral inclination are not associated with sex. However, tooth absence and bone changes in the mandibular condyle are related to mandibular fossa measurements.     

Effects of the closing and opening muscle groups on jaw condyle biomechanics after prominent mandibular angle osteotomy

ObjectivesThe aim of this study was to determine the effect of closing and opening muscle groups of the jaw on mandibular stability after prominent mandibular angle osteotomy, through three-dimensional finite element analysis (FEA).Materials and methodsSix patients with prominent mandibular angles, without malocclusion, were selected as finite element models of preoperative and postoperative prominent mandibular angle surgery. Computed tomographic (CT) scans were undertaken of the patients before and after surgery and three-dimensional images reconstructed using Simpleware software. The images were imported into an FEA software. Boundary-constrained and load conditions were applied. The solution process was run, and actions of closing and opening muscle groups were simulated and calculated.ResultsThe Von Mises stresses on the condyle position after the operation were higher than those before the operation. A significant difference was found between the stress distributions in the condyle position between prominent mandibular angle patients and mandibular angle ostectomy patients (P < 0.05).ConclusionsAfter osteotomy, the variation in force exerted by the closing and opening muscle groups of the jaw is one of the major factors affecting mandibular stability. FEA is a promising strategy in pre-surgical planning for improving surgical success and reducing complications.     

Tooth loss and craniofacial factors associated with changes in mandibular condylar morphology

Objective: To investigate the association between tooth loss and craniofacial factors with changes in mandibular condylar morphology.

Methods: A total of 123 patients participated in this cross-sectional study. The mandibular condylar morphology was evaluated using digital panoramic radiography. The exposure variables included gender, age group, molar relationship, facial growth pattern, facial asymmetry, dental midline, posterior crossbite, presence of fixed dental prosthesis, and tooth loss.

Results: Unilateral and bilateral mandibular condyle structural alterations were found in 20.3% and 28.5% of the sample, respectively. After the adjustment analysis, posterior crossbite (adjusted OR = 3.34, 95% CI = 1.23–9.06) and tooth loss (adjusted OR = 4.08, 95% CI = 1.72–9.64) were associated with the outcome. The tooth type associated with mandibular condyle structural alterations were premolars and upper molars.

Conclusion: The findings suggest that posterior crossbite and tooth loss are associated with mandibular condyle structural alterations.     

Three-dimensional virtual technology in reconstruction of mandibular defect including condyle using double-barrel vascularized fibula flap

ObjectiveThe aim of this study is to demonstrate the reconstruction of mandibular defects including the condyle using a double-barrel vascularized fibula flap aided by three-dimensional virtual technology.MethodsTen patients with the type H mandibular defects, who had undergone mandibular reconstruction using a double-barrel vascularized fibula flap, were reviewed for this study. Prior to the surgery, the patients CT scan data were analyzed virtually using SimPlant Pro? software (version 11.04). The simulation allowed construction of an individual mandibular model serving to guide the clinical operation.ResultsThe preoperative virtual surgery greatly benefitted the actual surgery. The vertical height of the neomandible and facial contour were precisely predicted. Some minor complications were encountered. Postoperative three-dimensional reconstruction revealed a close match with the simulated condyle.ConclusionA double-barrel vascularized fibula flap can provide sufficient bone, both in length and vertical height, for the reconstruction of a type H mandibular condylar defect. Combined virtual three-dimensional reconstruction and rapid prototyping can improve postoperative outcomes in mandibular reconstruction.     

Differences between the chewing and non-chewing sides of the mandibular first molars and condyles in the closing phase during chewing in normal subjects

ObjectiveThis study aimed to assess differences between the closing paths of the chewing and non-chewing sides of mandibular first molars and condyles during natural mastication, using standardized model food in healthy subjects.DesignThirty-two healthy young adults (age: 19–25 years; 22 men, 10 women) with normal occlusion and function chewed on standardized gummy jelly. Using an optoelectric jaw-tracking system with six degrees of freedom, we recorded the path of the mandibular first molars and condyles on both sides for 10 strokes during unilateral chewing. Variables were compared between the chewing side and the non-chewing side of first molars and condyles on frontal, sagittal, and horizontal views during the early-, middle- and late-closing phases.ResultsOn superior/inferior displacements, the chewing side first molar and condyle were positioned superior to those on the non-chewing side during the early- and middle-closing phases. Conversely, the first molar and condyle on the non-chewing side were positioned significantly superior to those on the chewing side during the late-closing phase. On anterior/posterior displacements, the chewing side mandibular first molar and condyle were positioned significantly posterior to those on the non-chewing side throughout all closing phases.ConclusionOur results showed the differences between the mandibular first molars and condyles on both sides with respect to masticatory path during natural chewing of a model food. These differences can be useful for informing initial diagnostic tests for impaired masticatory function in the clinical environment.     

Dental and maxillofacial features of condylo-mandibular dysplasia: A case series of 21 patients

IntroductionCamel-hump condylo-mandibular dysplasia is a specific form of condyle dysostosis, first described by Delaire. The aim of this study was to describe the clinical and radiographic phenotype of the disease, and to discuss therapeutic options.Case seriesTwenty-one patients were analyzed retrospectively. They exhibited the same unilateral facial asymmetry, which was of mandibular origin, with an elevated commissural line and occlusal cant, and a deviated chin on the side of the deformity. The soft tissues and the ears were always normal in terms of their physical appearance. Radiographic analysis generally revealed a short, curved, and anteriorly displaced condyle, with a high and sharp coronoid process. CT scans revealed that the glenoid fossa was empty. Twelve patients exhibited dental abnormalities, consisting mainly of dental inclusions affecting the lower first and/or second molars (10 patients). A good response to functional orthodontic treatment was achieved in eight patients, while 13 patients required a surgical mandibular lengthening procedure.ConclusionCondylo-mandibular dysplasia is a congenital condyle deformity that needs to be recognized and differentiated from craniofacial microsomia in order to be able to provide patient-specific treatments.     

Management of superolateral dislocation of the mandibular condyle: A retrospective study of 10 cases

IntroductionSuperolateral dislocation of the mandibular condyle (SDMC) is rarely described. The best treatment for superolateral dislocation of the fractured mandibular condyle (SDMC) is debated. This study investigated selection of the timing and techniques used in treating these fractures.Patients and methodsA retrospective clinical study was conducted on clinical data from 10 SDMC patients. Maximum mouth opening and occlusal relationships were compared following treatment using different techniques.ResultsThe 10 patients were followed for 6–25 months. Patients who had dislocation for less than 1 week had condylar reduction and rigid internal fixation of the fractures.Mandibular sagittal split ramus osteotomy and articular reduction and fixation were performed in seven cases. Postoperative mouth opening and occlusal relationships were satisfactory in all patients with the exception of one case with mouth opening of only 27 mm.ConclusionsFor all patients with superolateral dislocation, our first approach was to reduce the bone stump through surgery. When the dislocated joint had become adherent to the surrounding tissues and ankylosis developed, mandibular sagittal split ramus osteotomy was performed with good results.     

The influence of the closing and opening muscle groups of jaw condyle biomechanics after mandible bilateral sagittal split ramus osteotomy

ObjectiveTo investigate the influence of the closing and opening muscle groups of the jaw on mandibular stability after mandibular bilateral sagittal split ramus osteotomy (BSSRO).Materials and methodsTo establish finite element models of four conditions (the normal mandible, preoperative mandibular prognathism, postoperative (BSSRO) mandibular prognathism, and mandibular prognathism following virtual BSSRO), we imported Digital Imaging and Communications in Medicine (DICOM) data into three-dimensional reconstruction software. Finite element analysis software and statistical software were used for analysis of the condylar stress distribution as a function of condylar position during the actions of jaw closing and jaw opening muscle groups.ResultsThe stress distribution of the normal mandibular bilateral condyle was statistically different from the normal mandibular condyle, indicating that bilateral structures are asymmetrical. There was a significant difference in stress distributions with condyle position between healthy control patients and patients prior to mandibular prognathism surgery (P < 0.05). There was no significant difference in stress distributions between the normal mandible and the mandible following virtual surgery or real mandibular prognathism surgery. Additionally, there was no significant difference at 6 months after mandibular prognathism surgery (P > 0.05).ConclusionsBilateral structures of the normal mandible were asymmetrical. After mandibular bilateral sagittal split ramus osteotomy, variation of the force arms of closing and opening muscle groups of the jaw was one of the major factors influencing mandibular stability. Virtual surgery is a promising strategy for preoperative planning to improve surgical success and reduce complications.     

Impacted mandibular third molars and their influence on mandibular angle and condyle fractures – A retrospective study

BackgroundPrevious retrospective analyses prove that impacted mandibular third molars (M3s) increase the risk of angle fractures and decrease the risk of concomitant fractures to the condyle.Study designA retrospective cohort was designed for patients reported to the Department of Oral and Maxillofacial Surgery from January 2011 till June 2013. The study variables are presence or absence of third molar, if it is present, their position, classified using the Pell and Gregory system; angulation, classified using Shiller's method. The outcome variables were angle and condyle fractures.Materials and methodsHospital records and panoramic radiographs were used to determine and classify these variables.The study sample comprised of 118 mandibular angle and condyle fractures in 110 patients.Database was constructed and analysed using SPSS version 10.0.ConclusionThis present retrospective study concluded that the presence of impacted third molar predisposes the angle to fracture and reduces the risk of a concomitant condylar fracture. However absence of impacted third molar increases the risk of condylar fracture. The highest incidence of angle fracture was observed in position A impacted mandibular third molars. And there is no significant relationship, concerning ramus position and angulation of impacted mandibular third molars with the angle fracture.     

Histologic analysis of costochondral and sternoclavicular grafts in the TMJ of the juvenile monkey

Variability in growth response of the mandible after replacement of the mandibular condyle with the costochondral junction of a rib (CCJ) is common. Other donor graft sites that are more similar to the mandibular condyle might be more suitable for mandibular condylar replacement. Previous studies have shown the histomorphologic and developmental similarities between the sternoclavicular joint (SCJ) and temporomandibular joint (TMJ). The purpose of this study was to evaluate histologically short-term adaptations within the TMJ after replacement of the mandibular condyle with the autogenous sternal head of the clavicle, and to compare these adaptations with autogenous CCJ and mandibular condyle (surgical control) transplants. Bilateral vertical ramus osteotomies were performed in 12 juvenile Macaca mulatta with the left condyle being immediately replaced and the right condyle removed and replaced with either the sternal head of the clavicle or costochondral junction of a rib. All grafts were stabilized with maxillomandibular fixation for five weeks. Two animals in each group were killed at five, 11, and 17 weeks postsurgery and prepared for histologic analysis. The results indicate that: 1) incorporation of all grafts into the recipient site occurred and all animals had good mandibular function and occlusion throughout the follow-up period; 2) the clavicular and mandibular condylar grafts were incorporated sooner than the CCJ grafts; 3) clavicular graft changes resembled those of the condylar grafts histologically while the costal grafts remained inert and unchanged; and 4) a new condylar process with cartilage similar to that of a normal mandibular condyle regenerated in the costal graft animals from cells presumably contributed by the periosteum of the mandibular ramus and TMJ capsule.(ABSTRACT TRUNCATED AT 250 WORDS)     

Raloxifene reduces the risk of local alveolar bone destruction in a mouse model of periodontitis combined with systemic postmenopausal osteoporosis

OBJECTIVEPeriodontitis is characterized by local inflammation leading to tooth loss and severe destruction of alveolar bone. Raloxifene is a selective estrogen receptor modulator (SERM) that halts estrogen deficiency-induced systemic bone loss in postmenopausal osteoporosis without the side effects of cancer in breast and uterus. In this study, we examined the effects of raloxifene on alveolar bone mass in a mouse model with estrogen deficiency-induced periodontitis.METHODSPeriodontitis was induced by the injection of lipopolysaccharide (LPS) into the lower gingiva in ovariectomized (OVX) mice, and the alveolar bone and femur bone mineral density (BMD) were analyzed by dual-energy X-ray absorptiometry. To explore the direct osteoclast inhibitory effect of raloxifene, a co-culture system for osteoclast formation and organ culture of alveolar bone was established.RESULTSWhen OVX mice were treated with raloxifene, the bone loss in both alveolar bone and femur were abrogated. Interleukin 1 and/or LPS stimulated the osteoclast formation and bone-resorbing activity; however, raloxifene did not show any inhibitory effect on the osteoclast formation or function. In vivo local injection of raloxifene also did not prevent bone resorption in a mouse model of periodontitis. However, the systemic treatment of raloxifene using a mini-osmotic pump did prevent the loss of BMD of alveolar bone induced by LPS.CONCLUSIONThese results suggest that the SERM raloxifene systemically maintain alveolar bone mass in a mouse model of periodontitis with osteoporosis. Increasing the alveolar bone mass by SERMs treatment in patients with postmenopausal osteoporosis may be a useful approach to preventing the destruction of alveolar bone in late-onset periodontitis.     

Temporomandibular joint response to mandibular deviation in rabbits detected by 3D micro-CT imaging

PurposeMicro-computed tomography enables continuous and dynamic observation of the three-dimensional morphology of small structures. We observed morphological changes of the temporomandibular joint condyle under mandibular deviation continuously in an animal model by micro-computed tomography.MethodsTwelve Dutch rabbits were used (9 as experimental and 3 as control). In the experimental rabbits, the mandible was deviated posteriorly on the left side using an elastic band. Bilateral temporomandibular joints were scanned by micro-computed tomography preoperatively and at 3, 6, and 12 weeks after the operation. Histopathological examination was also carried out to confirm the changes.ResultsIt was shown that mandibular deviation induces condyle resorption in either ipsilateral or contralateral temporomandibular joint, which consequently makes the condyle smaller. Bone resorption settled down earlier in the contralateral joint and the quantity of bone resorption on the contralateral side was smaller than on the experimental side. Histopathological examination also showed destructive bone changes in the condyle, although they could not completely reflect the morphological changes.ConclusionsThese results suggested that reduction of the condylar size occurred as an adaptive change to mandibular deviation.     

Radiological Morphometric Analysis for the Trabecular Bone Structure of Mandibular Condyle after Ovariectomy in Mature Cynomolgus Monkeys

To investigate the effects of experimental osteoporosis on the trabecular structure of the mandibular condyle in cynomolgus monkeys by radiological bone morphometry ovariectomy (OVX) was performed on 10-year-old female cynomolgus monkeys which were fed a controlled diet for 2 years. Ten sham control groups were fed under the same conditions. Using a microfocus tube and computed radiography the removed mandibular condyle samples were imaged by standardized magnification radiography. The structural parameters were measured using radiological bone morphometric analysis. The bone mineral density (BMD) was measured by dual energy X-ray absorptiometry. The thickness of the cortical bone was measured using magnified radiographic images. The thickness of the cortical bone and the BMD in the OVX group were significantly lower than in the sham group. In the results of skeletal structure of the mandibular condyle the trabecular structure of the mandibular condyle was markedly deteriorated in the OVX group. The trabecular structure of the mandibular condyle for the OVX group was significantly decreased thus it was suggested that osteoporosis is a potential risk factor of osteoarthritis of the temporomandibular joint.     

Assessment of aging characteristics of female condylar trabecular structure by cone-beam computed tomography

Objectives

This study was performed to analyze the aging-related changes of the female condylar bone mineral density (BMD) and trabecular structure by cone-beam computed tomography (CBCT), and determine whether the condylar structure shows obvious changes after menopause.

Methods

The CBCT images of 160 female patients who met the inclusion criteria for the study were collected and divided into four groups by age (20–29 years, 30–39 years, premenopausal, and postmenopausal groups). Computer processing software CT-Analyser (Version 1.15.2.2+; SkyScan, Antwerp, Belgium) was used to measure the condylar BMD and related indexes, namely the bone volume/tissue volume ratio (BV/TV), trabecular number (Tb.N), trabecular thickness (Tb.Th), trabecular separation (Tb.Sp), trabecular structure model index (SMI), and bone surface area/volume ratio (BS/BV). SPSS 12.0 (SPSS Inc., Chicago, IL, USA) was used to analyze the radiographic findings and statistical differences.

Results

No significant differences were found between the bilateral condyles in each group (P?>?0.05). BV/TV, Tb.N, and Tb.Th of the condyle decreased with age, and the postmenopausal group showed significantly different values for each index compared with the other groups (P?<?0.01). Tb.Sp, SMI, and BS/BV of the condyle increased with age, and the postmenopausal group showed significantly different values for each index compared with the other groups (P?<?0.01).

Conclusions

With increasing age, the female condylar bone volume decreases, the Tb.N and Tb.Th decrease, the gap between the trabecular bone increases, and plate-like trabecular bone gradually transforms into a rod-like form. These changes are much more obvious in postmenopausal women.

     

Analysis of mandible trabecular structure using digital periapical radiographs to assess low bone quality in postmenopausal women

PurposeTo analyze the quality of mandibular trabecular structure in postmenopausal women using periapical radiographs. Postmenopausal women are subjected to low bone quality; hence, early detection methods are needed. In addition to bone mineral density (BMD), trabecular architecture must be assessed to determine bone quality. The mandible represents bone quality and allows the assessment of trabecular structure from periapical radiographs.Material and MethodsLumbar (BMDL) and femoral BMD (BMDF) examinations were performed using dual-energy X-ray absorptiometry (DXA) in 31 postmenopausal women and divided into normal, osteopenia, and osteoporotic groups. Periapical radiographs were taken at both posterior sites of the mandible. The region of interest was taken 2 mm from the apical root of the first molar. Trabecular parameters consisting of trabecular thickness (Tb.Th) and bone percentage (BA/TA) were measured using BoneJ.ResultsBoth trabecular parameters were significantly correlated with BMDF [BA/TA ​​(r = 0.3796; p < 0.05) and Tb.Th (r = 0.508; p < 0.05)]. BA/TA and Tb.Th were significantly different between the osteoporosis and normal groups (p < 0.05) contrast to osteopenia and normal groups (p > 0.05).ConclusionChanges in mandibular trabeculae structure in postmenopausal women can be assessed using periapical radiographs.     

Influence of prednisolone on craniofacial and long bones in growing rats: A cephalometric and peripheral quantitative computed tomographic analysis

Glucocorticoids are used for treatment of a variety of diseases, although they are also known to have an effect on skeletal growth and induce osteoporosis. The aim of this study was to investigate whether exposure to prednisolone had an effect on craniofacial bone growth and the internal bone structure in young rats. Twenty 5-week-old growing male rats were divided into two equal groups. Prednisolone at 30 mg/kg/day (prednisolone group) or no drug (control group) was administered orally on alternate days for 6 weeks. Thereafter, growth of the total skull, neurocranium, maxilla, and mandible was determined on lateral cephalograms, while cortical bone density and strength strain index (SSI) of the femur diaphysis and mandible were determined using peripheral quantitative computed tomography (pQCT). In addition, the femur length was measured. In the prednisolone group, total body weight, femur length, mandibular corpus length and height, and coronoid process height were reduced. No effects of prednisolone administration on cortical bone density of the femur and mandible were detected, however, the SSI values, cortical bone cross-sectional area, and mineral content of the femur and mandible, and cortical thickness and periosteal circumference of the femur in the prednisolone group were significantly lower when compared with the control group. The findings indicate that glucocorticoid administration decreases longitudinal and mandibular bone growth, quality, and strength in growing rats, whereas it has no significant effect on cortical bone density.     

3D vector analysis of mandibular condyle stability in mandibular setback surgery with bicortical bioabsorbable screw fixation

IntroductionBioabsorbable screws became widely used for stable fixation in orthognathic surgery as biomechanical technology advanced. Recently, 3D image analyses begin to be used to evaluate surgical changes. The purpose of this study was to evaluate, using 3D vector analysis, the stability of bicortical bioabsorbable screw fixation in mandibular setback using a sagittal split ramus osteotomy.Spatial change of the mandibular condyle was determined by 3D coordinates containing directional information.Materials and methodsBicortical screw fixation was performed using either a bioabsorbable screw (25 patients) or a titanium screw (5 patients) in orthognathic surgery. Pre- and post-operative CT images (6 months after surgery) were superimposed digitally. A 3D coordinate (X, Y, Z) and vectors were employed to quantify spatial changes of the condyle and analysed statistically.ResultsMeasuring on 3D image showed stable error about 0.16 mm. There were no significant differences in the total spatial changes of the condyle between titanium and bioabsorbable screws with the exception of the lateral–medial direction of the condylar centre (P = 0.042). The directional vector components were stable, regardless of mandibular setback.ConclusionIn 3D vector analysis, bioabsorbable screw fixation in SSRO with distal segment osteotomy shows clinically acceptable postoperative condylar position stability.