Biomechanical Loading Evaluation of Unsintered Hydroxyapatite/poly-l-lactide Plate System in Bilateral Sagittal Split Ramus Osteotomy.
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ABSTRACT:
SUBMITTER: Sukegawa S
PROVIDER: S-EPMC5551807 | biostudies-other | 2017 Jul
REPOSITORIES: biostudies-other
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Project description:A basic procedure affecting maxillofacial geometry is the bilateral sagittal split osteotomy. During the surgery, the bony segments are placed in a new position that provides the correct occlusion. Changes in the geometry of the mandible will affect the surrounding structures and will have a significant impact on the functioning of the masticatory system. As a result of the displacement of the bone segment, the biomechanical conditions change, i.e., the load and the position of the muscles. The primary aim of this study was to determine the changes in the values of the muscular forces caused by mandible geometry alteration. The study considered the translation and rotation of the distal segment, as well as rotations of the proximal segments in three axes. Calculations were performed for the unilateral, static loading of a model based on rigid body mechanics. Muscles were modeled as spring elements, and a novel approach was used to determine muscle stiffness. In addition, an attempt was made, based on the results obtained for single displacements separately, to determine the changes in muscle forces for geometries with complex displacements. Based on the analysis of the results, it was shown that changes in the geometry of the mandibular bone associated with the bilateral sagittal split osteotomy will have a significant effect on the values of the masticatory muscle forces. Displacement of the distal segment has the greatest effect from -21.69 to 26.11%, while the proximal segment rotations affected muscle force values to a less extent, rarely exceeding 1%. For Yaw and Pitch rotations, the opposite effect of changes within one muscle is noticed. Changes in muscle forces for complex geometry changes can be determined with a high degree of accuracy by the appropriate summation of results obtained for simple cases.
| S-EPMC8209381 | biostudies-literature
Project description:Bilateral sagittal split osteotomy (BSSO) is a widely-performed procedure in orthognathic surgery for the correction of dentofacial deformity. Condylar positioning is a critical step during BSSO to maximize functional and morphological results. The unsuitable positioning of condyles represents one of the causative mechanisms that may induce temporomandibular joint noxious effects after BSSO. Repositioning devices can assist surgeons in maintaining the preoperative condylar position; however, empirical repositioning methods based on experience gained are still commonly used. Trainee learning curves are difficult to assess. The aim of this study was to evaluate the relevance of computer-assisted surgery in the acquisition of condylar positioning skills. Forty-eight patients underwent BSSO performed by six maxillofacial trainees (four junior residents and two senior experienced residents). A condyle positioning system (CPS) was used by a senior surgeon to record a condylar position score during the procedure. Firstly, scores were recorded when the trainee manually positioned the condyle without access to the CPS score (phase 1) and then when the trainee positioned the condyle and performed osteosynthesis with visual access to the CPS score (phase 2). Six parameters describing condylar three-dimensional motions were assessed: translational motion from top to bottom (TB), back to front (BF), and left to right (LR), axial rotation (AR), sagittal rotation (SR), frontal rotation (FR), and a total score (TS). There were no significant differences between junior and senior residents in condyle positioning without access to the CPS. Condyles were significantly better positioned during phase 2 with access to the CPS (p<0.001). Over time, use of the CPS (phase 2) produced significantly quicker improvements in scores (p = 0.042). For those teaching surgeries to trainees, computer-assisted devices can potentially result in more rapid learning curves than traditional "observations-imitation" models. Use of a CPS by trainees facilitated condylar repositioning that resulted in an accurate occlusal result and avoidance of adverse effects on the temporomandibular joint.
| S-EPMC5918964 | biostudies-literature
Project description:Background:Sensory retraining could ameliorate neurosensory disturbance (NSD) resulting from the injury of the inferior alveolar nerve after a bilateral sagittal split osteotomy (BSSO). The aim of this study was to measure the effects of sensory retraining on NSD. Methods:A randomized, prospective, single-blinded clinical trial was conducted on consecutive patients with NSD resulting from a BSSO to correct skeletal class III malocclusion. The outcome measurement of sensory recovery was performed using a patient-centered survey assessed by the total score of questionnaire (TSQ) and visual analogue scale (VAS) at preoperation (T0), 1 week after surgery (T1), each month from 1 to 6 months after surgery (T2-T7), and 1 year after surgery (T8). Results:In total, 115 consecutive patients were randomized into a control group (56 patients without sensory retraining) or study group (59 patients with sensory retraining). TSQ and VAS values continually decreased from T1 to T8 in both groups. The study group tended to have lower, but not significantly lower, TSQ and VAS values than the control group at each postoperative time point. Women and men responded similarly to sensory retraining at each time point. The oldest patients did not respond well to sensory retraining, compared with the youngest patients, from T1 to T8, and this age effect evaluated by the VAS reached a significant difference at T7 and T8. Conclusion:NSD, assessed by the TSQ and VAS, continually decreased over time after the BSSO. Sensory retraining could improve NSD, but not significantly.
| S-EPMC5999438 | biostudies-literature
Project description:PurposeOur study aims to estimate the prevalence of lingual nerve injury following bilateral sagittal split osteotomy (BSSO).MethodsTwo reviewers independently conducted a systematic literature search in the Medline and Scopus databases. The pooled prevalence with 95% confidence intervals (CI) was estimated, and quality assessment, outlier analysis, and influential analysis were performed.ResultsIn total, eleven eligible studies comprising a total of 1,882 participants were included in this meta-analysis. One study was identified as critically influential. The overall prevalence of lingual sensory impairment was estimated to be as high as 0.1% (95% CI 0.0%-0.6%) with moderate heterogeneity observed between studies.ConclusionIt is important for healthcare professionals to be aware of this issue, despite the relatively low rate of lingual nerve deficit after BSSO. Additional research will provide a more comprehensive understanding of the underlying factors contributing to lingual nerve injury, leading to improved preventive measures and treatment strategies. Furthermore, insights gained from future studies will enable healthcare professionals to inform patients about the potential complications and manage their expectations before undergoing BSSO.
| S-EPMC11330379 | biostudies-literature
Project description:PurposeFacial asymmetry often persists even after mandibular deviation corrected by the bilateral sagittal split ramus osteotomy (BSSRO) operation, since the reference facial sagittal plane for the asymmetry analysis is usually set up before the mandibular menton (Me) point correction. Our aim is to develop a predictive and quantitative method to assess the true asymmetry of the mandible after a midline correction performed by a virtual BSSRO, and to verify its availability by evaluation of the post-surgical improvement.Patients and methodsA retrospective cohort study was conducted at the Hospital of Stomatology, Sun Yat-sen University (China) of patients with pure hemi-mandibular elongation (HE) from September 2010 through May 2014. Mandibular models were reconstructed from CBCT images of patients with pre-surgical orthodontic treatment. After mandibular de-rotation and midline alignment with virtual BSSRO, the elongation hemi-mandible was virtually mirrored along the facial sagittal plane. The residual asymmetry, defined as the superimposition and boolean operation of the mirrored elongation side on the normal side, was calculated, including the volumetric differences and the length of transversal and vertical asymmetry discrepancy. For more specific evaluation, both sides of the hemi-mandible were divided into the symphysis and parasymphysis (SP), mandibular body (MB), and mandibular angle (MA) regions. Other clinical variables include deviation of Me point, dental midline and molar relationship. The measurement of volumetric discrepancy between the two sides of post-surgical hemi-mandible were also calculated to verify the availability of virtual surgery. Paired t-tests were computed and the P value was set at .05.ResultsThis study included 45 patients. The volume differences were 407.8±64.8 mm3, 2139.1±72.5 mm3, and 422.5±36.9 mm3; residual average transversal discrepancy, 1.9 mm, 1.0 mm, and 2.2 mm; average vertical discrepancy, 1.1 mm, 2.2 mm, and 2.2 mm (before virtual surgery). The post-surgical volumetric measurement showed no statistical differences between bilateral mandibular regions.ConclusionsMandibular asymmetry persists after Me point correction. A 3D quantification of mandibular residual asymmetry after Me point correction and mandible de-rotation with virtual BSSRO sets up a true reference mirror plane for comprehensive asymmetry assessment of bilateral mandibular structure, thereby providing an accurate guidance for orthognathic surgical planning.
| S-EPMC5003338 | biostudies-literature
Project description:BackgroundBilateral sagittal split ramus osteotomy (BSSRO) is a common orthognatic surgical procedure. Sensory disturbances in the inferior alveolar nerve, including hypoesthesia and dysesthesia, are frequently observed after BSSRO, even without distinct nerve injury. The mechanisms that underlie individual differences in the vulnerability to sensory disturbances have not yet been elucidated.MethodsThe present study investigated the relationships between genetic polymorphisms and the vulnerability to sensory disturbances after BSSRO in a genome-wide association study (GWAS). A total of 304 and 303 patients who underwent BSSRO were included in the analyses of hypoesthesia and dysesthesia, respectively. Hypoesthesia was evaluated using the tactile test 1 week after surgery. Dysesthesia was evaluated by interview 4 weeks after surgery. Whole-genome genotyping was conducted using Illumina BeadChips including approximately 300,000 polymorphism markers.ResultsHypoesthesia and dysesthesia occurred in 51 (16.8%) and 149 (49.2%) subjects, respectively. Significant associations were not observed between the clinical data (i.e., age, sex, body weight, body height, loss of blood volume, migration length of bone fragments, nerve exposure, duration of anesthesia, and duration of surgery) and the frequencies of hypoesthesia and dysesthesia. Significant associations were found between hypoesthesia and the rs502281 polymorphism (recessive model: combined χ² = 24.72, nominal P = 6.633 × 10⁻⁷), between hypoesthesia and the rs2063640 polymorphism (recessive model: combined χ² = 23.07, nominal P = 1.563 × 10⁻⁶), and between dysesthesia and the nonsynonymous rs2677879 polymorphism (trend model: combined χ² = 16.56, nominal P = 4.722 × 10⁻⁵; dominant model: combined χ² = 16.31, nominal P = 5.369 × 10⁻⁵). The rs502281 and rs2063640 polymorphisms were located in the flanking region of the ARID1B and ZPLD1 genes on chromosomes 6 and 3, whose official names are "AT rich interactive domain 1B (SWI1-like)" and "zona pellucida-like domain containing 1", respectively. The rs2677879 polymorphism is located in the METTL4 gene on chromosome 18, whose official name is "methyltransferase like 4".ConclusionsThe GWAS of sensory disturbances after BSSRO revealed associations between genetic polymorphisms located in the flanking region of the ARID1B and ZPLD1 genes and hypoesthesia and between a nonsynonymous genetic polymorphism in the METTL4 gene and dysesthesia.
| S-EPMC3723511 | biostudies-literature
Project description:BackgroundThe aim of this study was to compare the dento-skeletal stability between one and three-screw fixation of mandible following bilateral sagittal split osteotomy (BSSO) in skeletal class 3 patients.MethodsHealthy patients with skeletal class 3 malocclusion in Mashhad, Iran, from August 2020 to May 2021 were undergone mandibular setback through bilateral sagittal split osteotomy. Rigid fixation was performed in one group with one-screw technique, and three-screw fixation was done in another group. Cephalogram x-rays were prepared and analyzed in three stages: before surgery (T0), one week after the surgery (T1), and six months postoperatively (T2). The linear and angular alterations of chosen multivariate skeletal and dental variables were evaluated and statistically compared in all three periods.ResultsThis study included a total of 20 patients, 12 of them were female (60%). Patients in the one-screw fixation group had a mean age of 20.6 ± 2.2 years old, whereas those in the three-screw fixation group were 21.5 ± 2.8 years old, with no statistically significant difference. Both groups had excellent mandibular stability six months following surgery. No statistically significant differences were observed in the postoperative skeletal and dental changes between the two techniques.ConclusionFixation of the mandible following the setback surgery by the BSSO technique with the one-screw fixation method may be accomplished effectively, and the therapeutic outcomes are comparable to those obtained with the traditional 3-screw fixation approach.
| S-EPMC9446116 | biostudies-literature
Project description:AimTo assess the efficacy of sagittal split plate with adjustable slider for intra-operative correction of condylar sag after bilateral sagittal split osteotomy.Subjects and methodsPatients reporting for correction of mandibular skeletal deformities for correction with sagittal split osteotomy (SSRO) were enrolled in the study. Simple randomization method was followed for patient allocation. Patients in group A had undergone fixation sagittal split fix plates; in group B, miniplate fixation with monocortical screws was used. Occlusion was the key indicator of condylar sage that was checked at different time frames (intra-operatively T0, immediate T1, 6 months postoperatively T2). Preoperative, immediate and late postoperative (at 6 months and 1-year interval) and lateral cephalometric assessment was used to assess their stability.ResultsThirty-three patients were enrolled and 20 patients were included in the study. One patient of group A presented with central condylar sag that was identified intra-operatively and addressed immediately. All the patients in group B presented with type 2 peripheral condylar sag that was addressed by inter-maxillary elastics and orthodontics. Two patients in group A presented with mild degree of relapse at 6 months, which was comparable to the control group indicating good stability.ConclusionSagittal split plates appear to be efficacious for intra-operative identification and correction of condylar sag is associated with SSRO.Supplementary informationThe online version contains supplementary material available at 10.1007/s12663-022-01782-7.
| S-EPMC9989057 | biostudies-literature
Project description:Maxillofacial skeletal surgery often involves the use of patient-specific implants. However, errors in obtaining patient data and designing and manufacturing patient-specific plates and guides can occur even with accurate virtual surgery. To address these errors, bespoke Snowman plates were designed to allow movement of the mandible. This study aimed to compare the stability of bespoke four-hole miniplates with that of a bespoke Snowman plate for bilateral sagittal split ramus osteotomy (SSRO), and to present a method to investigate joint cavity changes, as well as superimpose virtual and actual surgical images of the mandible. This retrospective study included 22 patients who met the inclusion criteria and underwent orthognathic surgery at a university hospital between 2015 and 2018. Two groups were formed on the basis of the plates used: a control group with four-hole bespoke plates and a study group with bespoke Snowman plates. Stability was assessed by measuring the condyle-fossa space and superimposing three-dimensional virtual surgery images on postoperative cone-beam computed tomography (CBCT) scans. No significant differences were observed in the condyle-fossa space preoperatively and 1 year postoperatively between the control and study groups. Superimposing virtual surgery and CBCT scans revealed minimal differences in the landmark points, with no variation between groups or timepoints. The use of bespoke Snowman plates for stabilizing the mandible following SSRO exhibited clinical stability and reliability similar to those with bespoke four-hole plates. Additionally, a novel method was introduced to evaluate skeletal stability by separately analyzing the condyle-fossa gap changes and assessing the mandibular position.
| S-EPMC10452001 | biostudies-literature
Project description:Novel biocomposites of poly(L-lactide) (PLLA) and poly(l-lactide-co-glycolide) (PLLGA) with 10 wt.% of surface-modified hydroxyapatite particles, designed for applications in bone tissue engineering, are presented in this paper. The surface of hydroxyapatite (HAP) was modified with polyethylene glycol by using l-lysine as a linker molecule. The modification strategy fulfilled two important goals: improvement of the adhesion between the HAP surface and PLLA and PLLGA matrices, and enhancement of the osteological bioactivity of the composites. The surface modifications of HAP were confirmed by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), TGA, and elemental composition analysis. The influence of hydroxyapatite surface functionalization on the thermal and in vitro biological properties of PLLA- and PLLGA-based composites was investigated. Due to HAP modification with polyethylene glycol, the glass transition temperature of PLLA was reduced by about 24.5 °C, and melt and cold crystallization abilities were significantly improved. These achievements were scored based on respective shifting of onset of melt and cold crystallization temperatures and 1.6 times higher melt crystallization enthalpy compared with neat PLLA. The results showed that the surface-modified HAP particles were multifunctional and can act as nucleating agents, plasticizers, and bioactive moieties. Moreover, due to the presented surface modification of HAP, the crystallinity degree of PLLA and PLLGA and the polymorphic form of PLLA, the most important factors affecting mechanical properties and degradation behaviors, can be controlled.
| S-EPMC7556045 | biostudies-literature