Bone Stress Research Articles

Effects of clear aligners combined with maxillary protractor on mixed dentition patient with skeletal class Ⅲ malocclusion: a finite element study

Objective: To compare the effects of expansion screw with maxillary protractor and clear aligners combined with maxillary protractor on the maxilla and maxillary dentition of mixed dentition patients with class Ⅲ skeletal malocclusion using finite element analysis, further providing clinical guidance for clear aligner treatment. Methods: A finite element model was established based on maxillofacial cone-beam CT data of a 10-year-old boy with mixed dentition, class Ⅲ skeletal malocclusion, who visited Department of Orthodontics, School of Stomatology, The Fourth Military Medical University in January, 2024. The expander with protractor group (group A) and the clear aligners with protractor group (group B) were divided. The arch was extended by 0.25 mm in both groups, and the forward pull force was 2.94 N (working condition 1) and 4.90 N (working condition 2), respectively. The initial displacement trend of maxilla and maxillary dentition in two groups under two working conditions were evaluated. Results: Under two working conditions, the maxilla of both groups showed clockwise rotation and labial inclination. The labial inclination of maxilla was more significant in clear aligners with protractor group, about 2.2-3.0 times that of expander with protractor group under the same working condition. Maxillary dentition showed mesial and buccal displacement, with anterior teeth extrusion and posterior teeth intrusion in two groups under two working conditions. Under the working condition 1 and 2, the labial displacement of central incisor of clear aligners with protractor group (-0.065, -0.089 mm) were greater than that in expander with protractor group (-0.024, -0.024 mm). Under two working conditions, the posterior teeth of expander with protractor group moved close to the buccal bodily direction, while those of clear aligners with protractor group moved tilted towards the buccal direction in the horizontal direction. The forward displacement trend of maxilla and maxillary dentition in clear aligners with protractor group was more obvious than expander with protractor group with the increase of the forward pull force. Under two working conditions, the anterior teeth' s hydrostatic stress of periodontal membrane and the equivalent stress of alveolar bone in clear aligners with protractor group were higher than those in expander with protractor group, mainly concentrated on the labial cervical region of the incisor. Conclusions: Clear aligners combined with maxillary protractor can produce forward force on the maxilla, but labial inclination occurs in the anterior teeth. It can be an effective orthopedic treatment strategy for mixed dentition patients with class Ⅲ skeletal malocclusion.

Semi-automated finite element analyses of surgically treated acetabular fractures to investigate the biomechanical behaviour of patient-specific compared to conventional implants

BackgroundIn acetabular fracture surgery, understanding the biomechanical behaviour of fractures and implants is beneficial for clinical decision-making about implant selection and postoperative (early) weightbearing protocols. This study outlines a novel approach for creating finite element models (FEA) from actual clinical cases. Our objectives were to (1) create a detailed semi-automatic three-dimensional FEA of a patient with a transverse posterior wall acetabular fracture and (2) biomechanically compare patient-specific implants with manually bent off-the-shelf implants.MethodsA computational study was performed in which we developed three finite element models. The models were derived from clinical imaging data of a 20-year-old male with a transverse posterior wall acetabular fracture treated with a patient-specific implant. This implant was designed to fit the patient's anatomy and fracture configuration, allowing for optimal placement and predetermined screw trajectories. The three FEA models included an intact hemipelvis for baseline comparison, one with a fracture fixated with a patient-specific implant, and another with a conventional implant. Two loading conditions were investigated: standing up and peak walking forces. Von Mises stress and displacement patterns in bone, implants and screws were analysed to assess the biomechanical behaviour of fracture fixation with either a patient-specific versus a conventional implant.ResultsThe finite element models demonstrated that for a transverse posterior wall type fracture, a patient-specific implant resulted in lower peak stresses in the bone (30 MPa and 56 MPa) in standing-up and peak walking scenario, respectively, compared to the conventional implant model (46 MPa and 90 MPa). The results suggested that patient-specific implant could safely withstand standing-up and walking after surgery, with maximum von Mises stresses in the implant of 156 MPa and 371 MPa, respectively. The results from the conventional implant indicate a likelihood of implant failure, with von Mises stresses in the implant (499 MPa and 1000 MPa) exceeding the yield stress of stainless steel.ConclusionThis study presents a workflow for conducting finite element analysis of real clinical cases in acetabular fracture surgery. This concept of personalized biomechanical fracture and implant assessment can eventually be applied in clinical settings to guide implant selection, compare conventional implants with innovative patient-specific ones, optimizing implant designs (including shape, size, materials, screw positions), and determine whether immediate full weight-bearing can be safely permitted.

Comparison of stress distribution around splinted and nonsplinted implants with different crown height space in posterior mandible: A finite element analysis study.

The purpose of this finite element analysis (FEA) study was to analyze the stress distribution on prosthetic components of splinted and nonsplinted prostheses, bone, and implants with different crown height space (CHS). Mandibular posterior segment was modeled with no resorption at the second premolar site and various amounts of resorption (0, 3, 6, and 9mm) at the first molar site. Two adjacent implants (Straumann bone level implants, 4.1 mm×8mm) were placed; at the second premolar site, the crown height was 8mm and at the first molar site, the crown height varied (8, 11, 14, and 17mm), depending on the amount of resorption. Both splinted and nonsplinted crowns were designed. Vertical and oblique loads of 400 N were applied to the crowns. von Mises stress was used to evaluate the stress distribution in the implant complex and maximum principal stress was used to evaluate the stress in the bone. When oblique forces were applied, the highest von Mises stresses were observed for nonsplinted crowns in the 17mm CHS group. The maximum principal and minimum principal stresses observed in bone under oblique loading increased with increased CHS for nonsplinted restorations. Crown height affected the amount of stress in bone and implant components. When the crown height difference between two adjacent implants increases, splinting may be crucial.

The Impact of Blood Flow Restriction Training on Tibial Bone Stress Injury Rehabilitation: An Exploratory Case Series.

Lower extremity bone stress injuries (BSI) are common injuries among athletes and military members. Typical management involves a period of restricted weightbearing which can have rapid detrimental effects upon both muscle and bone physiology. Few studies have investigated the effect of blood flow restriction (BFR) training on bone in the rehabilitative setting. The purpose of this study was to investigate the effects of lower extremity exercise with the addition of BFR upon bone mineral density, bone mineral content, and lean body mass in military members with tibial BSIs. Case series. Twenty military members with MRI-confirmed tibial BSI were recruited to complete lower extremity exercise with the addition of BFR twice per week for four weeks. The BFR cuff was applied proximally to the participant's involved limb while they performed gluteal, thigh, and leg resistance exercises. Outcomes were assessed at baseline and four weeks. The primary outcomes were whole leg bone mineral density (BMD), bone mineral content (BMC), and lean body mass (LM) as measured by dual-energy x-ray absorptiometry. Secondary outcomes included thigh and leg circumference measures and patient-reported outcomes, including the Lower Extremity Functional Scale (LEFS), Patient-Reported Outcomes Measurement Information System 57 (PROMIS-57), and Global Rating of Change (GROC). No significant differences were found in BMD (p=0.720) or BMC (p=0.749) between limbs or within limbs over time. LM was generally less in the involved limb (p=0.019), however there were no significant differences between or within limbs over time (p=0.404). For thigh circumference, significant main effects were found for time (p=0.012) and limb (p=0.015), however there was no significant interaction effect (p=0.510). No significant differences were found for leg circumference (p=0.738). Participants showed significant mean changes in LEFS (15.15 points), PROMIS physical function (8.98 points), PROMIS social participation (7.60 points), PROMIS anxiety (3.26 points), and PROMIS pain interference (8.39 points) at four weeks. The utilization of BFR in the early rehabilitative management of tibial BSI may help mitigate decrements in both bone and muscle tissue during periods of decreased physical loading. 4.

Automated External Bone Fixation Robot Design and Orthopedic Analysis

Background: Bone external fixation technology is an important therapeutic approach for limb correction, primarily involving a class of external fixation correction mechanisms. It has achieved good results in limb lengthening and correcting deformities to restore limb function. In clinical practice, existing correction mechanisms face challenges such as high resistance between components, complex installation procedures, and high precision requirements for installation, requiring manual adjustment by physicians, which limits precise control and quantification of correction parameters. Objective: To address these issues, an automated correction bone external fixation robot was designed based on traditional Ilizarov external fixation devices(TIEFD). Methods: By increasing the number of unidirectional hinge connections, the robot can effectively reduce motion resistance. Subsequently, the robot was combined with the tibia for correction motion simulation, obtaining the motion parameters θ of the deformed bones during the correction process based on the trajectory of the tibia's point mass. Finally, correction motion experiments and finite element analysis(FEA) were conducted on the robot combined with a control system. Results: The results showed that the robot could precisely control correction parameters, with the error range for rotational correction not exceeding 0.5 radians and the error range for traction correction not exceeding 0.2 mm. FAE, based on corrective force data, concluded that compared to (TIEFD), the robot could reduce bone stress by 16 MPa during the correction process. Conclusion: The robot effectively reduces patient discomfort, this provides a reliable theoretical basis for bone external fixation technology and holds positive significance for the treatment of skeletal deformities.

Periapical surgery and different root obturation protocols for upper central incisor: A finite elements analysis

BackgroundThe aim of this study was to determine the effect of root canal filling using different obturation materials combined with apicoectomy in upper central incisors under loading with 1 N and 100 N. The effect of incomplete root formation was also investigated. MethodsBased on a CBCT-scan, a model of an upper central incisor was created. The model was altered to simulate different clinical situations: root canal treatment, apicoectomy at two different lengths and with different obturation protocols, and immature root formation after trauma. In each model the tooth was loaded with 1 and 100 N, and peak Von Mises stress of bone and tooth, elastic strain of the periodontal ligament, as well as rotation and displacement of the tooth were measured. ResultsPeriapical surgery increases stress in dentin and the surrounding bone. Different obturation materials only produce minor differences in a coronally intact tooth. ConclusionsInterincisal angle or loading direction strongly affects all measured values and needs to be considered when planning periapical surgery or comparing finite element analysis. Immature roots show the highest stress values in this study, reaching half the yield strength of dentine.

Educational Intervention Improves Female Athlete Triad Awareness in Female Collegiate Swimmers

Introduction: The Female Athlete Triad (Triad) is characterized by high energy expenditure and low caloric intake, leading to dysregulation of menstruation and bone metabolism. Triad-associated relative energy deficiency in sport (REDs) adversely affects performance and mental health. Risk factors are underrecognized in swimmers, who are less likely to present with bone stress injuries because of swimming’s non-weightbearing nature. Our objective was to quantify knowledge about the Triad and REDs among collegiate swimmers and demonstrate the value of educational intervention. Methods: Members of two Division III women’s varsity swim teams completed a Qualtrics survey, consisting of 35 Triad and REDs questions, and 13 demographics questions. Participants then attended an in-person, 20-minute educational session focused on Triad risk factors and prevention, after which they completed a post-session survey. The post-session survey contained 13 additional questions using a Likert scale, where 1=Strongly Agree and 5=Strongly Disagree. Pre- and post-session data were analyzed using Microsoft Excel. Results: Thirty-one swimmers were included. Pre-session, 9.7% of respondents named one or more Triad components, compared to 96.8% after (p<0.0001). 9.7% could define the REDs acronym pre-session, compared to 87.1% after (p<0.0001). Participants better understood the Triad post-session (mean Likert score=1.23) and found the session helpful (mean=1.23), but in a hypothetical scenario, felt relatively uncomfortable contacting medical staff about Triad symptoms (mean=1.87, p=0.0002). Of the 35.5% who believed they may be experiencing Triad components, 72.7% indicated the session motivated them to seek help. Conclusions: Female collegiate swimmers’ low baseline Triad and REDs knowledge improved significantly after an educational intervention. Survey responses highlighted the importance of heightened Triad awareness, but also its continued stigmatization. The session encouraged swimmers with self-identified Triad symptoms to seek help, underscoring the importance of continued education efforts, especially in sports where the Triad is underrecognized.

Differences in cricket fast bowling kinematics between grass and artificial surface pitches

ABSTRACT Cricket fast bowling training and research are often conducted on artificial turf, while matches are played on natural grass. It is unknown if technique differs between the different surfaces; therefore, the aim of this study was to explore if fast bowling technique differed between surfaces. Shoe slip distance and kinematic and temporal parameters previously associated with ball release velocity and lumbar bone stress injury were determined for eight male sub-elite fast bowlers using three-dimensional motion analysis on grass and artificial surfaces. Paired t-test and statistical parametric mapping were used to identify differences in technique between surfaces. Significantly greater slip distance was observed during back and front foot contact on the artificial surface compared to bowling on the grass surface. No kinematic or temporal parameter significantly differed between surfaces, therefore fast bowling technique is likely similar between grass and artificial surfaces, and previous research utilising artificial surfaces in fast bowling research is likely to be valid.

Design of functionally graded porous lattice structure tibial implant for TAR

Use of porous lattice structures and functionally graded (FG) implants in orthopaedic applications has emerged as a promising solution to reduce stress shielding. However, there is a notable research gap in examining the effects of post-operative scenarios within the lattice pores and different porosity distribution laws in functionally graded porous lattice structure (FGPLS) implants on the biomechanical performance of tibial implant for total ankle replacement (TAR). The objective of the study is to investigates the effects of both post-operative tissues and various porosity distribution laws on the biomechanical performance of tibial implant for TAR and proposes a new design strategy. CAD models for lattice structures at various porosities were developed to incorporate the effects of post-operative tissues such as fibrous tissue, cartilage, immature bone, and mature bone. The pore spaces of these lattice structures were assumed to be filled with the post-operative ingrowth tissues. The lattice structure and these tissues together form the Representative volume element (RVE), whose effective properties were calculated using Asymptotic homogenization (AH) technique. Equations linking mechanical properties and porosity were established and used to assign mechanical properties to macro-FE models of FGPLS tibial implants based on three different power laws i.e. n = 0.1,1 and 5. Macro-FE models for intact and implanted tibia bones were developed using homogeneous properties of cortical bone and heterogeneous cancellous bone properties. The proximal part of the tibia was fixed, and a compressive load was applied through the anterior nodes of the meniscal bearing to represent dorsiflexion loading during normal walking. The Finite Element Analysis (FEA) was utilized to investigate the biomechanical performance of these implanted models in terms of stress distribution in the tibia bone and implant-bone micromotion. A comparison was made between models with solid metallic implants and those with FGPLS implants. Additionally, models with varying post-operative tissues in the pore space were compared, as well as models with different porosity variation laws were also compared. Results demonstrated that models implanted with FGPLS implants having porosity variation based on power law n = 0.1 showed increased bone stress and micromotion compared to those with solid metallic implants. Specifically, in models with FGPLS implants with porosity variation based on a power law of n = 0.1, the bone area with stress ranging from 2–5 MPa increased significantly in the periprosthetic region compared to models with solid metallic implants. The bone stress value for the majority of the region above the medial and lateral peg increased from 1–2 MPa to 2–5 MPa. Although there was a slight increase in micromotion values, they remained below the acceptable threshold of 50 µm. Models with porosity variations based on power laws n = 1 and n = 5 exhibited similar bone stress and micromotion results as solid metallic implants. Additionally, no significant difference in bone stresses was observed for different stages of bone ingrowth at pore space. These findings indicate that both the porous structure and porosity distribution within the implant significantly influence the biomechanical performance of tibial implants for TAR. So, it can be concluded that FGPLS implants with power law n = 0.1 are effective in reducing stress shielding and supporting the long-term survival of TAR by increasing bone stress and reducing the chances of aseptic loosening due to implant induced adaptive bone remodelling.

Multivitamin Compliance Reduces Injuries of Female Recruits at Air Force Basic Training: A Randomized Controlled Cohort Study.

Department of the Air Force basic military training (BMT) is the 7.5-week initial entry training for all enlisting U.S. Air Force and Space Force recruits. Overuse musculoskeletal injuries (MSKI) during training threaten success in BMT, and trainees with nutritional deficiencies are at higher risk. Several efforts are made at BMT to mitigate these issues to help trainees graduate on time, such as the distribution of multivitamins (MVI) to female recruits. However, trainee compliance with the prescribed MVI has been reported to be low, calling into question the effectiveness of this intervention. This study evaluated the effect of briefing modality offered to these trainees at the time of distribution on educational effectiveness, MVI compliance, and injury rates. This was a randomized controlled cohort study of BMT female trainees. Subjects included all female trainees of a single iteration of BMT concurrently completing training within the same squadron. At the outset of training, cohorts were randomly educated in one of two ways regarding the provided MVI. The control cohort (n = 80) was presented with the standard educational video created by BMT-registered dietitians, while the test cohort (n = 79) was presented the video and then also briefed in-person by a group of subject matter experts. At the end of BMT, the trainees completed a questionnaire regarding their knowledge, confidence, and compliance with the MVI. Additionally, a routinely collected training database was queried and analyzed for differences in injuries and training outcomes using the chi-squared test with significance set to α ≤ 0.05. Although both cohorts found their educational presentation useful, the "in-person" cohort reported significantly higher compliance rates and were found to be diagnosed with MSKI and bone stress injuries at significantly lower rates (43% and 66% relative risk reductions, respectively). Education to female BMT trainees regarding the MVI, which included a face-to-face discussion with subject matter experts, resulted in greater compliance and reduced incidence of MSKI and bone stress injury, compared to a video prepared by registered dietitians alone. Such educational approaches should continue to be strived for in this and other military population health measures. This study's implication of MVI efficacy for injury risk reduction in female trainees should be further studied, verified, and improved upon in this and other populations.

Bone stress injuries in athletics (track and field) championships: findings from a prospective injury surveillance conducted across 24 international championships with 29,147 registered athletes

BackgroundAthletics (track and field) athletes are prone to develop bone stress injuries (BSIs) but epidemiological data on BSIs from top-level sports events are scarce.ObjectiveTo describe the incidence and characteristics of BSIs during 24 international athletics championships held from 2007 to 2023.MethodsBSI-related data were prospectively collected during 24 international athletics championships, including the Olympic Games (n = 3), World Outdoor Championships (n = 4), European Outdoor Championships (n = 6), World Indoor Championships (n = 3) and European Indoor Championships (n = 8). Descriptive and comparative statistics were used to assess the epidemiological characteristics of BSIs.ResultsBSIs accounted for 1.5% of all reported injuries (n = 36; 1.2 per 1000 registered athletes (95%CI 0.8 to 1.6)). No significant difference of BSI incidence was detected between female (2.0 per 1000 athletes (95%CI: 0.9 to 2.3)) and male athletes (0.9 per 1000 athletes (95%CI: 0.4 to 1.4)) (relative risk (RR) = 1.73, 95%CI: 0.88 to 3.40). BSI incidence was significantly higher during outdoor championships (1.6 per 1000 registered athletes (95%CI: 1.0 to 2.1)) as compared to indoor championships (0.2 per 1000 registered athletes (95%CI: 0.0 to 0.5)) (RR = 10.4, 95%CI: 1.43 to 76.0). Most BSIs were sustained in the foot (n = 50%) or leg (n = 33%). BSIs were reported in athletes participating in endurance disciplines (52.8%) or in explosive disciplines (47.2%).ConclusionsBSIs represent a small portion of injuries sustained during international athletics championships. Collective results suggest that injury rates are higher in outdoor competitions as compared to indoor competitions. The most common injury locations comprise the foot and leg.Clinical Trial NumberNot applicable.

Comparison of implant placement at crestal and subcrestal levels in aesthetic zone: A finite element analysis.

The success rate of the implant treatment, including aesthetics and long-term survival, relies heavily on preserving crestal peri-implant bone, as it determines the stability and long-term outcomes. This study aimed to demonstrate the stress differences in the crestal bone resulting from dental implant placement at various depths relative to the crestal bone level using finite element analysis. Three study models were prepared for implant placement at the crestal bone level (CL), 1 mm depth (SL-1),and 2mm depth (SL-2). Implants were placed in the maxillary central incisor region of each model, and 100 N vertical and oblique forces were applied. The von Mises, maximum principal (tensile), and minimum principal (compressive) stresses were evaluated. The CL model exhibited the highest stresses on the implant, abutment, and abutment screws under vertical and oblique forces. For maximum principal stress in the crestal bone under vertical force, the SL-2, SL-1, and CL models recorded values of 6.56, 6.26, and 5.77MPa, respectively. Under oblique forces, stress values for SL-1, SL-2, and CL were 25.3, 24.91, and 23.76MPa, respectively. The CL model consistently exhibited the lowest crestal bone stress at all loads and the highest stress values on the implant and its components. Moreover, considering the yield strengths of the materials, no mechanical or physiological complications were noted. Placing the implant at the crestal level or subcrestally beyond the cortical layer could potentially reduce stress and minimize crestal bone loss. However, further studies are warranted for confirmation.

Evaluation of Surface Morphology and Stress Distribution of Orthodontic Mini-implants in Maxilla: A Three-dimensional Finite Element Study

Objectives: Inaccurate design, insertion or loading of mini-implant may lead to disturbed bone turnover and subsequent implant failure. This study assesses the two commonly used types of implants and their bone stress pattern and determines which type of implant may be more patient-compatible. Method: The samples were categorized into four groups and analyzed by scanning electron microscopy to assess the surface morphology. Stress distribution was estimated using finite element method for which three-dimensional (3D) models of the maxilla and mini-screws were prepared. The implant was then inserted 5 mm from the alveolar crest onto the buccal cortical plate of maxilla between the second premolar and first molar within the platform of Ansys Workbench software. Two loads were applied: 5 Ncm and 2 N. Evaluation of von Mises stresses in the bone was estimated. Results: The study concluded that tapered stainless steel screws exerted greater stress on the bone than titanium screws in both situations. As the diameter increased from 1.3 mm to 1.5 mm, the mini-screw displacement and stress were less. Under 2 N force, the stress was distributed around the head and neck of the mini-implant and the cortical bone. Conclusion: The assessment of von Mises stress distributed around an orthodontic mini-implant under a constant load revealed that stainless steel mini-screws generated more stress than titanium mini-screws. It was observed that the majority of the stress and strain is tolerated by the cortical bone, not the cancellous bone. The diameter of mini-screw is more significant irrespective of material composition.

Cross-sectional size, shape, and estimated strength of the tibia, fibula and second metatarsal in female collegiate-level cross-country runners and soccer players

Bone stress injuries (BSIs) frequently occur in the leg and foot long bones of female distance runners. A potential means of preventing BSIs is to participate in multidirectional sports when younger to build a more robust skeleton. The current cross-sectional study compared differences in tibia, fibula, and second metatarsal diaphysis size, shape, and strength between female collegiate-level athletes specialized in cross-country running (RUN, n = 16) and soccer (SOC, n = 16). Assessments were performed using high-resolution peripheral quantitative computed tomography and outcomes corrected for measures at the radius diaphysis to control for selection bias and systemic differences between groups. The tibia in SOC had a 7.5 % larger total area than RUN, with a 29.4 % greater minimum second moment of area (IMIN) and 8.2 % greater estimated failure load (all p ≤ 0.02). Tibial values in SOC exceeded reference data indicating positive adaptation. In contrast, values in RUN were similar to reference data suggesting running induced limited tibial adaptation. RUN did have a larger ratio between their maximum second moment of area (IMAX) and IMIN than both SOC and reference values. This suggests the unidirectional loading associated with running altered tibial shape with material distributed more in the anteroposterior (IMAX) direction as opposed to the mediolateral (IMIN) direction. Comparatively, SOC had a similar IMAX/IMIN ratio to reference data suggesting the larger tibia in SOC resulted from multiplane adaptation. In addition to enhanced size and strength of their tibia, SOC had enhanced structure and strength of their fibula and second metatarsal. At both sites, polar moment of inertia was approximately 25 % larger in SOC compared to RUN (all p = 0.03). These data support calls for young female athletes to delay specialization in running and participate in multidirectional sports, like soccer, to build a more robust skeleton that is potentially more protected against BSIs.

In vivo glycation-interplay between oxidant and carbonyl stress in bone.

Metabolic syndromes (eg, obesity, type 2 diabetes (T2D), atherosclerosis, and neurodegenerative diseases) and aging, they all have a strong component of carbonyl and reductive-oxidative (redox) stress. Reactive carbonyl (RCS) and oxidant (ROS) stress species are commonly generated as products or byproducts of cellular metabolism or are derived from the environment. RCS and ROS can play a dual role in living organisms. Some RCS and ROS function as signaling molecules, which control cellular defenses against biological and environmental assaults. However, due to their high reactivity, RCS and ROS inadvertently interact with different cellular and extracellular components, which can lead to the formation of undesired posttranslational modifications of bone matrix proteins. These are advanced glycation (AGEs) and glycoxidation (AGOEs) end products generated in vivo by non-enzymatic amino-carbonyl reactions. In this review, metabolic processes involved in generation of AGEs and AGOEs within and on protein surfaces including extracellular bone matrix are discussed from the perspective of cellular metabolism and biochemistry of certain metabolic syndromes. The impact of AGEs and AGOEs on some characteristics of mineral is also discussed. Different therapeutic approaches with the potential to prevent the formation of RCS, ROS, and the resulting formation of AGEs and AGOEs driven by these chemicals are also briefly reviewed. These are antioxidants, scavenging agents of reactive species, and newly emerging technologies for the development of synthetic detoxifying systems. Further research in the area of in vivo glycation and glycoxidation should lead to the development of diverse new strategies for halting the progression of metabolic complications before irreversible damage to body tissues materializes.

To Evaluate the Favourable Distribution Pattern of Stress in Maxilla and Mandible during Maxillary Protraction Using Miniplates of Varying Diameters and Thread Pitches under Different Levels of Inter Maxillary Forces: A Study Using Finite Element Analysis

Introduction The aim of the study is to compare the stress distribution pattern by three different diameters of miniplate (1.5 mm, 2 mm, 2.5 mm) of three different mini- implant thread pitches (0 .5 mm, 1 mm, 1.5 mm), in the maxilla and mandible during maxillary protraction using different inter-maxillary elastic force of (2 N,4N,6N,8 N).  Materials and Methods Using Autocad software and plate geometry, a 3D finite element model of the maxilla was made with a miniplate at the infrazygomatic buttress and a mandibular miniplate at the mandibular parasymphysis. Stress distributions and displacements were analyzed in Von Mises stress form using Ansys software.  Results In the implant study, the Von Mises stress in bone (Mpa) was 142 Mpa for the 1 mm diameter implant, which was the lowest compared to 170 Mpa for the 0.5 mm pitch and 233 Mpa for the 1.5 mm pitch. Whereas in skull study when 2N elastic force was applied for a 2 mm diameter minimplant, the maximum Von Mises stress at 0.5mm,1mm and 1.5mm thread pitch was (18.454 Mpa, 18.47 Mpa, and 18.344 Mpa. For elastic force of 4N was (18,465 Mpa, 18.492 Mpa and 18.244 Mpa), for 6N elastic force was 18.388 Mpa, 18.43 Mpa and 18.086 Mpa), and for 8N was (18.272 Mpa, 18.324 Mpa and 17.883 Mpa), which was similar compared from other two diameters.  Conclusion When comparing 1.5 mm, 2 mm, and 2.5 mm diameter implants with 0.5 mm, 1 mm, and 1.5 mm pitch thread , the 2 mm diameter at 1 mm pitch thread shows the least strained bone in the implant study. Whereas,in the skull study, 2 mm diameter mini-implants had similar stress distribution in the maxilla and mandible,in all the thread pitches and elastic force which shows pitch variants and different force application is not a factor for stress distribution in the bone.

Biomechanical analysis of patient specific cone vs conventional stem in revision total knee arthroplasty

BackgroundIn revision total knee arthroplasty, addressing significant bone loss often involves the use of cemented or press-fit stems to ensure implant stability and long-term fixation. A possible alternative to stem was recently introduced utilizing custom-made porous metaphyseal cones, designed to reconstruct the missing tibial and femoral geometries. Early clinical and radiological assessments have shown promising results. The objective of this research was to biomechanically evaluate the performances of these custom-made cones.MethodsThe biomechanical study was conducted using a validated finite element model. The bone geometries of a patient (selected for their history of four knee revisions due to infection and periprosthetic fractures, followed by a successful treatment with custom-made 3D-printed metaphyseal cones) were employed for the study. On these bone models, different revision scenarios were simulated and examined biomechanically: (A) custom-made cementless metaphyseal cones; (B) cemented stems; (C) press-fit stems; (D) distal femoral reconstruction with press-fit stem. All the models were analyzed at 0 °and 90 °of flexion, under physiological load conditions simulating daily activities; stress distribution, average Von-Mises stresses and risk of fracture were then analyzed and compared among configurations.ResultsThe use of custom-made 3D-printed cones exhibited the most favorable stress distribution in both femoral and tibial bones. Tibial bone stress was evenly distributed in custom-made cone configurations, while stress concentration was observed in distal regions for the other scenarios. Additionally, custom-made cones displayed overall homogeneity and lower stress levels, potentially contributing to limit pain. Symmetrical stress distribution was observed between the lateral and medial proximal tibia in custom-made cone models, whereas other scenarios exhibited uneven stress, particularly in the anterior tibial bone.ConclusionsThe biomechanical analysis of porous custom-made metaphyseal cones in re-revision arthroplasties is in agreement with the positive clinical and radiological outcomes. These findings provide valuable insights into the potential benefits of using custom-made cones, which offer more uniform stress distribution and may contribute to improve patient outcomes in revision TKA procedures. Further studies in this direction are warranted to validate these biomechanical findings.

Effect of force direction and impaction angulation during dilaceration impacted central incisor traction: a finite element analysis

BackgroundThe effects of traction forces at different angles on impacted central incisors(ICI)with varying inverted angles (IA) may be different. The objective of this study was to analyze the biomechanical effects of different force directions (FD) on developmentally inverted ICI with multi-angle variations and to offer insights and guidance for the treatment of inverted ICI.MethodsThree-dimensional finite element method was employed to simulate clinical scenarios of inverted ICI traction. As such, 0.2 N of force (direction: antero-superior angles of 90°, 100°, 110°, 120°, and 130° relative to the long axis of the inverted ICI crown) was applied to the inverted ICI with inverse angles (IA) of 40°, 30°, 20°, 10° and 0°. Inverted ICI apical displacement and Von Mises stress on periodontal ligament (PDL) and alveolar bone were compared.ResultsIA and FD showed minimal influence on the stress distribution in the PDL, as higher stresses were concentrated in the apical region. The higher stresses in the alveolar bone are focused on the cervical and apical regions of the tooth. In particular, IA exerts a more significant impact on stress distribution in the alveolar bone than FD. The influence of IA on the apical displacement of inverted ICI is larger than that of FD.ConclusionsTo promote the health of the root and periodontal tissues, it is recommended to use an angle of 100°-110° relative to the long axis of the ICI crown when dealing with a large IA (> 20°) developmentally inverted ICI. Conversely, an angle of 110°-120° can be used.

Influence of Body Weight Measurement Frequency on the Bone Health of Female Athletes

ABSTRACT Purpose: Athletes struggle with bone stress injuries despite the many risk factors reported in previous studies. However, the relationship between body weight measurement frequency and risk of stress fractures has yet to be investigated. Thus, the purpose of this study is to seek the link between body weight measurement frequency and the occurrence of stress fractures. Method: This cross-sectional study included female athletes who were requested to fill out an anonymous online survey regarding their personal background, including the history of amenorrhea and stress fractures. In addition, the frequency at which they measured their body weight and composition and whether they had to report the same to their coaches and seniors were asked. Results: A total of 172 collegiate female athletes for 28 different types of sports participated in this study. Among the included athletes, 35.7% had a history of amenorrhea, whereas 29.7% had a history of stress fractures. A total of 57.0% of the athletes answered that in their team, they measure their body weight on a regular basis, and 33.1% of the athletes answered that they reported the data to their coaches. Logistic regression analysis revealed that those who measured their body weight at least once a day had a higher risk of sustaining stress fractures than did those who measured their body weight less than once a day (OR = 2.36, 95% CI 1.06–5.27, p = .04). Conclusion: Body weight measurement frequency was associated with the risk of stress fractures in female collegiate athletes.

Biomechanical Comparison of Corticopedicular Spine Fixation versus Pedicle Screw Fixation in a Lumbar Degenerative Spondylolisthesis Finite Element Analysis Model

To compare the stability of a corticopedicular posterior fixation (CPPF) device with traditional pedicle screws for decompression and fusion in adult degenerative lumbar spondylolisthesis. Finite element analysis (FEA) was used in a validated model of grade 1 L4-L5 spondylolisthesis to compare segmental stability after laminectomy alone, laminectomy with pedicle screw fixation, or laminectomy with CPPF device fixation. A 500-N follower load was applied to the model and different functional movements were simulated by applying a 7.5-Nm force in different directions. Outcomes included degrees of motion, tensile forces experienced in the CPPF device, and stresses in surrounding cortical bone. At maximum loading, laminectomy alone demonstrated a 1° increase in flexion range of motion, from 6.35° to 7.39°. Laminectomy with pedicle screw fixation and CPPF device fixation both reduced spinal segmental motion to ≤1° at maximum loading in all ranges of motion, including flexion (0.94° and 1.09°), extension (-0.85° and -1.08°), lateral bending (-0.56° and -0.96°), and torsion (0.63° and 0.91°), respectively. There was no significant difference in segmental stability between pedicle screw fixation and CPPF device fixation during maximum loading, with a difference of ≤0.4° in any range of motion. Tensile forces in the CPPF device remained ≤51% the ultimate load to failure (487 N) and stress in surrounding cortical bone remained ≤84% the ultimate stress of cortical bone (125.4 MPa) during maximum loading. CPFF fixation demonstrated similar segmental stability to traditional pedicle screw fixation whereas tensile forces and stress in surrounding cortical bone remained below the load to failure.