Biomechanical effects of maxillary expansion on a patient with cleft palate: A finite element analysis.
Ontology highlight
ABSTRACT:
SUBMITTER: Lee H
PROVIDER: S-EPMC5557378 | biostudies-other | 2016 Aug
REPOSITORIES: biostudies-other
Similar Datasets
Project description:ObjectivesTo determine the three-dimensional changes of the nasal septum (NS), alveolar width, alveolar cleft volume, and maxillary basal bone following rapid maxillary expansion (RME) in consecutive patients with unilateral cleft lip and palate (UCLP).Materials and methodsA retrospective investigation was conducted based on the analysis of cone-beam computed tomography (CBCT) data of 40 consecutive patients with UCLP (mean age 11.1 ± 2.2 years). Scans were acquired prior to RME (T0) and after removal of the expander (T1) before graft surgery. A three-dimensional analysis of the effects of RME on the nasal septum, alveolar width, alveolar cleft volume, and maxillary basal bone was performed.ResultsNo changes in the NS deviation were observed following RME (P > .05). Significant increases of the alveolar transverse dimension were found in the anterior (14.2%; P < .001) and posterior (7.7%; P < .001) regions as well as in the volume of the alveolar cleft (19.6%; P < .001). No changes in the basal bone dimensions and morphology were observed (P > .05).ConclusionsFollowing RME, no changes were observed in the NS and maxillary basal bones of patients with UCLP despite the significant gain in the anterior and posterior alveolar width and the increase of the alveolar cleft defect. Clinicians should be aware that maxillary changes following RME in patients with UCLP are restricted to the dentoalveolar region.
| S-EPMC8032269 | biostudies-literature
Project description:Excessive forces may cause root resorption and insufficient forces would introduce no effect in orthodontics. The objective of this study was to investigate the optimal orthodontic forces on a maxillary canine, using hydrostatic stress and logarithmic strain of the periodontal ligament (PDL) as indicators. Finite element models of a maxillary canine and surrounding tissues were developed. Distal translation/tipping forces, labial translation/tipping forces, and extrusion forces ranging from 0 to 300 g (100 g=0.98 N) were applied to the canine, as well as the force moment around the canine long axis ranging from 0 to 300 g·mm. The stress/strain of the PDL was quantified by nonlinear finite element analysis, and an absolute stress range between 0.47 kPa (capillary pressure) and 12.8 kPa (80% of human systolic blood pressure) was considered to be optimal, whereas an absolute strain exceeding 0.24% (80% of peak strain during canine maximal moving velocity) was considered optimal strain. The stress/strain distributions within the PDL were acquired for various canine movements, and the optimal orthodontic forces were calculated. As a result the optimal tipping forces (40-44 g for distal-direction and 28-32 g for labial-direction) were smaller than the translation forces (130-137 g for distal-direction and 110-124 g for labial-direction). In addition, the optimal forces for labial-direction motion (110-124 g for translation and 28-32 g for tipping) were smaller than those for distal-direction motion (130-137 g for translation and 40-44 g for tipping). Compared with previous results, the force interval was smaller than before and was therefore more conducive to the guidance of clinical treatment. The finite element analysis results provide new insights into orthodontic biomechanics and could help to optimize orthodontic treatment plans.
| S-EPMC6052357 | biostudies-literature
Project description:Background: Spinopelvic fractures and approaches of operative stabilization have been a source of controversial discussion. Biomechanical data support the benefit of a spinopelvic stabilization and minimally invasive procedures help to reduce the dissatisfying complication rate. The role of a cross connector within spinopelvic devices remains inconclusive. We aimed to analyze the effect of a cross connector in a finite element model (FE model). Study Design: A FE model of the L1-L5 spine segment with pelvis and a spinopelvic stabilization was reconstructed from patient-specific CT images. The biomechanical relevance of a cross connector in a Denis zone I (AO: 61-B2) sacrum fracture was assessed in the FE model by applying bending and twisting forces with and without a cross connector. Biomechanical outcomes from the numerical model were investigated also considering uncertainties in material properties and levels of osseointegration. Results: The designed FE model showed comparable values in range-of-motion (ROM) and stresses with reference to the literature. The superiority of the spinopelvic stabilization (L5/Os ilium) ± cross connector compared to a non-operative procedure was confirmed in all analyzed loading conditions by reduced ROM and principal stresses in the disk L5/S1, vertebral body L5 and the fracture area. By considering the combination of all loading cases, the presence of a cross connector reduced the maximum stresses in the fracture area of around 10%. This difference has been statistically validated (p < 0.0001). Conclusion: The implementation of a spinopelvic stabilization (L5/Os ilium) in sacrum fractures sustained the fracture and led to enhanced biomechanical properties compared to a non-reductive procedure. While the additional cross connector did not alter the resulting ROM in L4/L5 or L5/sacrum, the reduction of the maximum stresses in the fracture area was significant.
| S-EPMC8188498 | biostudies-literature
Project description:IntroductionThe aim of this study was to evaluate three dimensionally the effect of the combined maxillary expansion and protraction treatment on oropharyngeal airway in children with non-syndromic cleft palate with or without cleft lip (CP/L).MethodsCBCT data of 18 preadolescent individuals (ages, 8.4 ± 1.7 years) with CP/L, who underwent Phase I orthodontic maxillary expansion with protraction, were compared before and after treatment. The average length of treatment was 24.1± 7.6 months. The airway volume and minimal cross-sectional area (MCA) were determined using 3DMD Vultus imaging software with cross-sectional areas calculated for each 2-mm over the entire length of the airway. A control group of 8 preadolescent individuals (ages, 8.7 ± 2.6 years) with CP/L was used for comparison.ResultsThere was a statistically significant increase in pharyngeal airway volume after phase I orthodontic treatment in both groups, however, there was no statistically significant change in minimal cross-sectional area in neither study nor control group.ConclusionThe findings showed that maxillary expansion and protraction did not have a significant effect on increasing oropharyngeal volume and MCA in patients with CP/L.
| S-EPMC6667113 | biostudies-literature
Project description:Cleft lip with or without cleft palate (CLP) is considered the most frequent congenital malformations of the head and neck, with cleft individuals exhibiting more chances of presenting abnormalities such as developmental defects of enamel (DDE). Matrix metallopeptidase 2 (MMP2) is a membrane-bound protein with collagen-degrading ability and has important roles in tooth formation and mineralization. The aim of this study was to evaluate the frequency, location, severity and extent of DDE found in the maxillary incisors for groups of individuals born with CLP, as well as understanding their relationship with the cleft side. Besides, this study addresses the hypothesis that DDE can be influenced by variation in the MMP2 genes (rs9923304). Individual samples, clinical history, intraoral photographs and panoramic radiographs were obtained from 233 patients under treatment at the Cleft Lip and Palate Service of the University Hospital Lauro Wanderley at the Federal University of Paraíba. Digital images were examined by the same evaluator using the Classification of Defects According to the Modified DDE Index, and then loaded into the Image Tool software, where two measurements were made: total area of the buccal surface (SA) and the area of the DDE (DA), obtaining the percentage of the surface area affected (%SAD) (ICC = 0.99). Genomic DNA was extracted from saliva samples from 124 participants. Genotyping was carried out using TaqMan chemistry for one marker in MMP2 (rs9923304). Statistical analyses were performed by The Jamovi Project software. The Shapiro-Wilk test was applied, followed by the Student's t-test and the Mann-Whitney test. Chi-square and Fisher's exact tests, and odds ratio (OR) with 95% confidence interval (CI) calculations were used to determine Hardy-Weinberg equilibrium and statistically significant differences with an alpha of 0.05. No significant differences in the prevalence and extent of enamel defects were found between male and female individuals born with CLP (p = 0.058256). The frequency of individuals presenting teeth with DDE, in relation to the cleft and non-cleft side, was statistically different (p <0.001; OR = 7.15, CI: 4.674> 7.151> 10.942). However, the averages of %SAD were similar (p = 0.18). The highest means of the %SAD were found in individuals with bilateral cleft lip with or without cleft palate (BCLP) when compared to individuals with unilateral cleft lip with or without cleft palate (UCLP), for the teeth inside (IA) and outside the cleft area (OA) (p <0.001). Regardless of the cleft side, individuals with BCLP were 7.85 times more likely to have more than one third of the tooth surface affected, showing more frequently defects in the three thirds (OA: p <0.001) (IA: p = 0.03), as well as a higher frequency of more than one type of defect (OA: p = 0.000358) (IA: p = 0.008016), whereas in UCLP, defects were isolated and restricted to only one third, more frequently, the incisal third (OA: p = 0.009) (IA: p = 0.001), with greater frequency of milder defects, such as demarcated (p = 0.02) and diffuse (p = 0.008) opacities. A higher frequency of the T allele, less common, was observed in the group of CLP individuals who had all the affected teeth or at least two teeth with %SAD greater than 20% (p = 0.019843). Our results suggest that MMP2 may have a role in the cases that presented DDE and genotyping rs9923304 could serve as the basis for a genomic approach to define risks for individuals born with CLP. Frequency and severity of DDE is strongly related to the CLP phenotype, since the highest values were found for BCLP. However, the extent of the DDE is independent of its relationship with the side of the cleft.
| S-EPMC7769421 | biostudies-literature
Project description:PurposeTo theoretically compare corneal displacement and the von Mises (VM) stress distribution of deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PK) for keratoconus (KC) and to evaluate the effects of residual stromal thickness (RST) and intraocular pressure (IOP) on postoperative corneal biomechanics.MethodsWe performed DALK and PK simulations using Ansys by employing anisotropic nonlinear hyperelastic corneal material properties. We analyzed corneal displacement and VM stress in DALK and PK models under IOPs of 10, 15, 20, and 25 mmHg. We established two DALK models: The ideal-type DALK ensured that postoperative central corneal thickness was constant at 560 µm and the corneal graft thickness varied with RST. The clinical-type DALK ensured that corneal grafts had the same thickness (500 µm) regardless of RST. Then we analyzed the effects of RST and IOP on postoperative corneal displacement and VM stress.ResultsCorneal displacement and VM stress were lower in the DALK than in the PK model. In the ideal-type DALK model, an increase in RST was associated with increased deformation and decreased VM stress in the healing zone, except for a RST of 0 µm. In the clinical-type DALK model, deformation and VM stress in the healing zone decreased with an increase in RST, except for a RST of 0 µm.ConclusionsDALK showed more stability than PK. For the ideal-type DALK model, an increase in RST resulted in decreased postoperative corneal biomechanics in the healing zone. For the clinical-type DALK model, corneal deformation and VM stress decreased with an increase in RST, which provides numerical evidence for the design of corneal transplantation for patients with KC.Translational relevanceIn this computational modeling study, we first theoretically compared corneal biomechanics between DALK and PK for KC. Then, the effects of RST and IOP on postoperative corneal biomechanics were investigated. Our findings provide novel insights into the optimal design for corneal transplantation for patients with KC.
| S-EPMC8363774 | biostudies-literature
Project description:BackgroundTo reduce morbidity to cleft patients, new approaches have been developed and here, we report for the first time the use of deciduous dental pulp stem cells (DDPSC) associated with a hydroxyapatite-collagen sponge (Bio-Oss Collagen® 250 mg, Geistlich) for closing alveolar defects during secondary dental eruption, further comparing these results to historical controls.MethodsSix patients, aged 8 to 12, were selected. Autologous DDPSC were isolated from each patient, then associated with the biomaterial and this bone tissue engineered set was used to fill the alveolar defect. Computed tomography was performed to assess both preoperative and 6- and 12-month postoperative outcomes. Overall morbidity was recorded. Historical controls consisted of sixteen patients previously selected and randomly assigned to group one (rhBMP-2) or group two (iliac crest bone graft).ResultsDDPSC could be isolated and characterized as mesenchymal stem cells. Progressive alveolar bone union has occurred in all patients. Similarly to group two 75.4%, SD ± 4.0, p > 0.999, but statistically different from group one (59.6%, SD ± 9.9, p > 0.999, but statistically different from group one (59.6%, SD ± 9.9.ConclusionFor this selected group of patients, DDPSC therapy resulted in satisfactory bone healing with excellent feasibility and safety, which adds significantly to the prospect of stem cell use in clinical settings. Clinical Question/Level of Evidence. Therapeutic, II. This trial is registered with https://clinicaltrials.gov/ct2/show/NCT01932164?term=NCT01932164&rank=1.
| S-EPMC7091546 | biostudies-literature
Project description:Background/objectiveHigh tibial osteotomy (HTO) is a common treatment for medial knee arthrosis. However, a high rate of complications associated with a plate and a significant loss of correction have been reported. Therefore, an internal support block (ISB) is designed to enhance the initial stability of the fixation device that is important for successful bone healing and maintenance of the correction angle of the osteotomy site. The purpose of this study was performed to examine if an internal support block combined with a plate reduces the stress on the plate and screw area.MethodsFinite element models were reconstructed following three different implant combinations. Two loading conditions were applied to simulate standing and initial sit-to-stand postures. Data analysis was conducted to evaluate the axial displacement of the posteromedial tibial plateau, which represents the loss of the posteromedial tibial plateau in clinical observation. Moreover, the stresses on the bone plate and locking screws were evaluated.ResultsCompared to the TomoFix plate, the ISB reduced the axial displacement by 73% and 76% in standing and initial sit-to-stand loading conditions, respectively. The plate with an ISB reduced stress by 90% on the bone plate and by 73% on the locking screw during standing compared to the standalone TomoFix plate. During the initial sit-to-stand loading condition, the ISB reduced the stress by 93% and 77% on the bone plate and the locking screw, respectively.ConclusionThe addition of the PEEK block showed a benefit for structural stability in the osteotomy site. However, further clinical trials are necessary to evaluate the clinical benefit of reduced implant stress and the internal support block on the healing of the medial bone tissue.
| S-EPMC7906299 | biostudies-literature
Project description:Posterior fixation is superior to anterior fixation in the correction of kyphosis and maintenance of spinal stability for the treatment of thoracic spinal tuberculosis. However, the process of selecting the appropriate spinal fixation method remains controversial, and preoperative biomechanical evaluation has not yet been investigated. In this study, we aimed to analyze the application of the assisted finite element analysis (FEA) and the three-dimensional (3D) printed model for the patient-specific preoperative planning of thoracic spinal tuberculosis. An adult patient with thoracic spinal tuberculosis was included. A finite element model of the T7-T11 thoracic spine segments was reconstructed to analyze the biomechanical effect of four different operative constructs. The von Mises stress values of the implants in the vertical axial load and flexion and extension conditions under a 400-N vertical axial pre-load and a 10-N?m moment were calculated and compared. A 3D printed model was used to describe and elucidate the patient's condition and simulate the optimal surgical design. According to the biomechanical evaluation, the patient-specific preoperative surgical design was prepared for implementation. The anterior column, which was reconstructed with titanium alloy mesh and a bone graft with posterior fixation using seven pedicle screws (M+P) and performed at the T7-T11 level, decreased the von Mises stress placed on the right rod, T7 pedicle screw, and T11 pedicle. Moreover, the M+P evaded the left T9 screw without load bearing. The 3D printed model and preoperative surgical simulation enhanced the understanding of the patient's condition and facilitated patient-specific preoperative planning. Good clinical results, including no complication of implants, negligible loss of the Cobb angle, and good bone fusion, were achieved using the M+P surgical design. In conclusion, M+P was recommended as the optimal method for preoperative planning since it enabled the preservation of the normal vertebra and prevented unnecessary internal fixation. Our study indicated that FEA and the assisted 3D printed model are tools that could be extremely useful and effective in the patient-specific preoperative planning for thoracic spinal tuberculosis, which can facilitate preoperative surgical simulation and biomechanical evaluation, as well as improve the understanding of the patient's condition.
| S-EPMC7379841 | biostudies-literature
Project description:Background/objectiveUntil 2010, adults underwent surgical treatment for maxillary expansion; however, with the advent of micro-implant-assisted rapid maxillary expansion (MARME), the availability of less invasive treatment options has increased. Nevertheless, individuals with severe transverse maxillary deficiency do not benefit from this therapy. This has aroused interest in creating a new device that allows the benefit of maxillary expansion for these individuals. The aim of this study was to evaluate the efficacy of three MARME models according to tension points, force distribution, and areas of concentration in the craniofacial complex when transverse forces are applied using finite element analysis.Materials and methodsDigital modeling of the three MARME models was performed. Model A comprised five components: one body screw expander and four adjustable arms with rings for mini-implant insertion. These arms have an individualized height adjustment that allows MARME positioning according to the patient's palatal anatomy, thereby preventing body screw expander collision with the lateral mucosa in severe cases of maxillary deficiency. Model B was a maxillary expander with screw rings joined to the body, and model C was similar to model B, except that model C had open rings for the insertion of the mini-implants. Through the MEF (Ansys software), the stresses, distribution, and area of concentration of the stresses were evaluated when transverse forces of 7.85 N were applied.ResultsThe three models maintained the following pattern: model C presented weak stress peaks with limited distribution and lower concentration area, model B obtained median stress peaks with better distribution when compared to that of model C, and model A showed better stress distribution and larger concentration area. In model A, tensions were located in the lateral lamina of the pterygoid process, which is an important site for maxillary expansion. The limitation of the present study was that it did not include the periodontal tissues and muscles in the finite element method evaluation.ConclusionsModel A showed the best stress distribution conditions. In cases of severe atresia, model A seems to be an excellent option.
| S-EPMC8217479 | biostudies-literature