Search Results (63)

Oral health is a very important issue today. This approach presents an original idea: to model the dental implant as a double-articulated buckling bar on an elastic environment. The mandibular bone is considered as the elastic environment. The buckling bar is analyzed using the Transfer-Matrix Method. The risk of buckling is higher for straight bars subjected to axial compression. Therefore, knowing the critical buckling force is very important, especially in the case of dental implants. This study, based on the Transfer-Matrix Method, was carried out in two steps. In the first step, a double-articulated buckling bar on a rigid environment is considered. The second step involves studying the same doubly articulated bar, but with the joint at the lower end resting on an elastic environment. The bone in which the implant is placed is considered as this elastic environment. The Transfer-Matrix Method is easy to implement and provides quick results for problems involving the shape optimization of structural components. This article presents a completely new idea and an original approach to buckling analysis, with applications to dental implants. This work will serve as a foundation for future research involving experimental investigations of dental implants. Full article

Background: The development of robust artificial intelligence (AI) models for diagnosing Temporomandibular Disorders (TMDs) is severely constrained by data scarcity and patient privacy regulations. Cone-beam computed tomography (CBCT), the gold standard for assessing osseous changes in the temporomandibular joint (TMJ), inherently contains sensitive biometric facial features, making de-identification difficult without losing critical anatomical information. This study aims to develop and evaluate TMJCTGenerator, a specialized latent diffusion model (LDM) framework designed to synthesize high-fidelity, diverse, and anonymous TMJ CBCT images. We hypothesize that this LDM approach can achieve superior anatomical fidelity and diversity compared to traditional generative adversarial network (GAN)- and variational autoencoder (VAE)-based methods, specifically in capturing fine osseous details within sagittal and coronal views of the mandibular condyle. Methods: A training dataset comprising 348 anonymized CBCT volumes was obtained in this retrospective comparative study to extract high-resolution sagittal and coronal regions of interest of the mandibular condyle. An independent test set of 39 anonymized CBCT volumes was further included. We developed a class-conditional LDM that integrates a pre-trained VAE for perceptual compression with a conditional U-Net for iterative denoising in the latent space. Performance was evaluated via qualitative anatomical fidelity assessment, Fréchet Inception Distance (FID), and a blinded Visual Turing test conducted by experienced clinicians to determine the distinguishability of synthetic images from real data. Results: Qualitative analysis revealed that TMJCTGenerator produced images with superior sharpness and anatomical consistency compared to baseline models, successfully reconstructing fine bone structures essential for diagnosing degenerative joint disease. TMJCTGenerator achieved lower FID scores than both VAE and GAN baselines. In the visual Turing test, clinicians were unable to reliably distinguish the generated images from real scans, and non-inferiority analysis confirmed that the synthetic data were statistically non-inferior to real data. Furthermore, TMJCTGenerator demonstrated the capability to generate diverse pathological conditions, ranging from normal anatomy to severe osteoarthritic changes. Conclusions: The proposed LDM framework effectively addresses the data scarcity and privacy bottlenecks in TMJ AI research by generating realistic, fully anonymous medical imaging data. TMJCTGenerator outperforms traditional generative methods in both visual fidelity and diversity, offering a viable solution for training downstream diagnostic algorithms. The source code and pre-trained models of TMJCTGenerator have been made open-source. Full article

Background: Adult patients with a thin buccal cortical plate and fragile periodontal phenotype are at high risk of dehiscence, fenestration and recession during transverse orthodontic expansion. Conventional mechanics often create a cervical compression-dominant environment that exceeds the adaptive capacity of the periodontal ligament (PDL)–bone complex. Objectives: This study proposes an integrative mechanobiological model in which a skeletal-anchorage-assisted loading protocol (Bone Protection System, BPS) transforms expansion into a tension-dominant regime that favours buccal phenotype preservation. Methods: Patient-specific finite element models were used to compare conventional expansion with a BPS-modified force system. Regional PDL stress patterns and crown/apex displacement vectors were analysed to distinguish tipping-dominant from translation-dominated mechanics. A pilot CBCT proof-of-concept (n = 1 thin-phenotype adult) with voxel-based registration quantified changes in maxillary and mandibular alveolar ridge width and buccal cortical plate thickness before and after BPS-assisted expansion. The mechanical findings were integrated with current evidence on compression- versus tension-driven inflammatory and osteogenic pathways in the PDL and cortical bone. Results: FEM demonstrated that conventional expansion concentrates high cervical compressive stress along the buccal PDL and cortical surface, accompanied by bending-like crown–root divergence. In contrast, the BPS protocol redirected forces to create a buccal tensile-favourable region and a more parallel crown–apex displacement pattern, indicative of translation-dominated movement. In the proof-of-concept (n = 1) CBCT case, BPS-assisted expansion was associated with preservation or increase of buccal ridge dimensions without radiographic signs of cortical breakdown. Conclusions: A tension-dominant orthodontic loading environment generated by a skeletal-anchorage-assisted force system may support buccal cortical preservation and vestibular phenotype reinforcement in thin-phenotype patients. The proposed mechanobiological model links these imaging and FEM findings to known molecular pathways of inflammation, angiogenesis and osteogenesis. It suggests a functional biomaterial-based strategy for widening the biological envelope of safe tooth movement. Full article

Introduction: The trigeminocardiac reflex (TCR) is a brainstem reflex in which trigeminal stimulation precipitates abrupt vagally mediated cardiovascular changes, ranging from bradycardia to asystole. While classically described during down-fracture or pterygomaxillary disjunction in Le Fort I osteotomy, rhinocardiac events from lateral nasal wall manipulation are less emphasized in orthognathic surgery. Case presentation: A 32-year-old man undergoing Le Fort I osteotomy developed ventricular asystole during lateral nasal osteotomy. The maneuver was stopped immediately; chest compressions and a single dose of epinephrine were administered, with return of spontaneous circulation within approximately one minute. Surgery was aborted and the patient was transferred to the surgical ICU. Clinical discussion: The temporal association with lateral nasal wall manipulation, in the setting of controlled hypotension and multimodal anesthesia, is most compatible with a peripheral (V2) TCR-type event, although drug-related and hemodynamic contributors cannot be excluded. A mini review of orthognathic TCR reports underscores recurring high-risk steps (down-fracture, pterygomaxillary disjunction, mandibular maneuvers) and highlights lateral nasal osteotomy as a potential additional trigger. Management principles remain the immediate cessation of the stimulus, optimization of oxygenation and ventilation, anticholinergics for bradycardia, and epinephrine/advanced cardiac life support for instability or arrest. Conclusion: Lateral nasal osteotomy may trigger a TCR-like event with severe bradyarrhythmia or asystole during Le Fort I osteotomy, particularly in hemodynamically vulnerable patients. Anticipation, swift recognition, and prompt, protocolized management are essential for favorable outcomes. Full article

Background: Myogenous temporomandibular disorders (TMDs) typically present with pain but without obvious restriction of mandibular motion, making subtle dysfunctions difficult to detect clinically. In this study, we evaluated mandibular kinematics in myogenous TMDs using an electronic axiography system (Cadiax Diagnostic). The specific objective of this study was to evaluate whether patients with myogenous temporomandibular disorders exhibit qualitative abnormalities in mandibular movements that are not detectable using conventional clinical examination. Methods: Twenty-six patients with myogenous TMD (muscle pain without intra-articular disorders, diagnosed per DC/TMD) and 26 matched controls were examined. Clinical assessment (DC/TMD Axis I) measured mandibular range of motion and deviations. Instrumental recordings of maximal opening, protrusion, and laterotrusion were obtained with Cadiax 4. Quantitative (excursion ranges) and qualitative (movement symmetry and sagittal deviations) parameters were analyzed. Condylar position changes between the reference position and maximum intercuspation were evaluated (Condyle Position Measurement, CPM). Exact χ² or Fisher tests were applied with effect sizes (φ) and 95% confidence intervals (CI). Results: Maximal opening, lateral excursions, and protrusion ranges were statistically similar between groups (mean opening: 47.96 ± 6.5 mm in TMDs vs. 49.46 ± 5.4 mm in controls, p = 0.40; 95% CI of difference −1.8 to 4.8 mm). However, qualitative deviations were more frequent in TMD. Of note, 12/26 (46.2%) patients vs. 6/26 (23.1%) controls showed a ΔY deflection during protrusion (χ² = 3.06, p = 0.08; φ ≈ 0.24; difference = 23.1%, 95% CI −2.0–48.2%). Identical proportions (46.2% vs. 23.1%) showed a ΔY deflection upon opening (χ² = 3.06, p = 0.08). Inferior condylar shifts (distractions) on closing into intercuspation occurred only in the mTMD group: 5/26 (19.2%) left condyles vs. 0% (p ≈ 0.05; 95% CI diff 4.1–34.4%) and 2/26 (7.7%) right vs. 0% (p ≈ 0.49; 95% CI −2.5–17.9%). Condylar compressions (superior shifts) were similar between groups. In summary, roughly half of TMD patients exhibited lateral jaw deflections (ΔY) and exclusive condylar “distraction” on closure; upon comparison, these conditions were rare in controls. Conclusions: Despite normal mandibular range of motion, patients with myogenous TMDs exhibited qualitative abnormalities in jaw kinematics, including movement deflections, condylar asymmetries, and centric–intercuspal discrepancies. Axiographic analysis with Cadiax enabled detection of subtle functional changes not identifiable in routine examinations, underscoring its diagnostic value in early dysfunction and potential therapeutic planning. The detection of kinematic abnormalities could influence early diagnosis or treatment planning for myogenous TMDs. Full article

Despite the significant ongoing development of fixation materials, plate breakages still occur after osteosynthesis of the mandibular condyles. The aim of this study is to demonstrate the complications caused by fixation material breakages in the hope of inspiring the development of new, more durable plates; we analyzed a total of 238 plates used for osteosynthesis in this anatomical region. Cases where compression screws were used as the sole fixation material were excluded. Plate breakage was found in six cases, which accounted for 2.52% of treated individuals. It seems that most plate breakages can be avoided by maintaining effective patient supervision for up to 6 months after surgery. Risk factors for breakage are identified and guidelines for improving the design of future plates are provided. By analyzing some plate design features, we provide some indications for improving their strength and improving their designs for use in this field. Full article

Background and Clinical Significance: Tooth impaction is a developmental anomaly characterized by the inability of a tooth to emerge into its predetermined anatomical position within the oral cavity during the normal eruption period. Impaction of the mandibular second premolar is an uncommon condition and poses a heightened risk of neurosensory injury when the tooth is adjacent to the mental foramen. Early diagnosis and precise planning are therefore essential. Case Presentation: This case report presents a rare instance of an asymptomatic impacted mandibular second premolar located in close proximity to the mental foramen in a 44-year-old female patient. The impaction was discovered incidentally on an orthopantomogram, and Cone-Beam Computed Tomography (CBCT) confirmed intimate contact between the root of the impacted second premolar and the mental nerve. Surgical removal was performed under local anesthesia via a conservative triangular flap and a corticotomy window. Platelet-Rich Fibrin (PRF) generated from autologous blood was placed in the socket to foster healing. The proximity of the mental foramen dictated minimal bone removal and atraumatic luxation to avoid nerve stretch or compression. PRF was selected as an effective biomaterial shown to accelerate soft tissue healing and moderate postoperative discomfort, potentially reducing the likelihood of neurosensory disturbance. The socket presented satisfactory healing, and neurosensory function was normal at the first week follow-up and remained normal at 7 months postoperatively (longest follow-up), and no complications were reported by the patient. Conclusions: CBCT-guided planning, meticulous surgical techniques, and adjunctive PRF allowed for safe extraction without post-operative paraesthesia. Timely identification of such rare impactions broadens treatment options and minimizes complications. Full article

This study aimed to evaluate the biomechanical effects of implant length, mandibular morphology, graft application, loading timing, and force direction on peri-implant stress distribution using finite element analysis (FEA). Five mandibular models representing normal, atrophic, and graft-augmented conditions were constructed. Each model was analyzed with 6 mm and 12 mm Straumann Standard implants under two loading types, vertical (200 N) and oblique (100 N at 30°), across three loading protocols (immediate, early, and delayed). Stress analysis was conducted using von Mises and principal stress criteria, focusing on cortical and trabecular bone, the implant–abutment complex, and the mandibular canal. Under vertical loading, increasing the implant length from 6 mm to 12 mm reduced the maximum tensile stresses in trabecular bone from 0.930 MPa to 0.475 MPa (an approximate 49% decrease). However, oblique loading caused a substantial increase in stresses in all regions, with trabecular compressive stress reaching up to −19.102 MPa and cortical tensile stress up to 179.798 MPa in the atrophic mandible. Graft application significantly reduced peri-implant stresses; for example, maximum compressive stress in the cortical bone decreased from −227.051 MPa in the atrophic model to −13.395 MPa in the grafted model under similar loading conditions. Although the graft donor site was not explicitly modeled, the graft material (Bio-Oss) was anatomically positioned in the posterior mandible to simulate buccolingual augmentation and its biomechanical effects. Stress concentrations around the mandibular canal remained below the 6 MPa threshold for neurovascular injury in all scenarios, indicating a biomechanically safe outcome. These findings indicate that oblique loading and reduced bone volume may compromise implant survival, whereas graft application plays a critical role in mitigating stress levels and enhancing biomechanical stability. The study also emphasizes the importance of considering force direction and bone quality in clinical planning, and highlights the novelty of combining graft simulation with FEA to assess its protective role beyond implant length alone. Full article

Background: Temporomandibular disorders (TMD) are common musculoskeletal conditions affecting the temporomandibular joints, masticatory muscles, and associated structures. Their etiology is complex and multifactorial, involving anatomical, behavioral, and psychosocial contributors. Parafunctional habits such as clenching, grinding, and abnormal jaw positioning have been proposed as contributing factors, yet their individual and cumulative contributions remain unclear. This exploratory cross-sectional study aimed to evaluate the prevalence and severity of parafunctional habits and their association with TMD in medical students—a group exposed to elevated stress levels. Subjects were examined in Krakow, Poland, using the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) protocol. Methods: Participants completed a 21-item Oral Behavior Checklist (OBC) assessing the frequency of oral behaviors on a 0–4 scale. A self-reported total parafunction load was calculated by summing individual item scores (range: 0–84). Logistic regression was used to evaluate associations between individual and total parafunction severity scores and TMD presence. Results: The study included 66 individuals aged 19–30. TMD was diagnosed in 55 participants (83.3%). The most commonly reported habits were resting the chin on the hand (90.9%) and sleeping in a jaw-compressing position (86.4%). Notably, jaw tension (OR = 14.5; p = 0.002) and daytime clenching (OR = 4.7; p = 0.027) showed significant associations with TMD in the tested population. Each additional point in the total parafunction score increased TMD odds by 13.6% (p = 0.004). Conclusions: These findings suggest that parafunctional behaviors—especially those involving chronic muscle tension or abnormal mandibular positioning—may meaningfully contribute to the risk of TMD in high-stress student populations. Moreover, the cumulative burden of multiple low-intensity habits was also significantly associated with increased TMD risk. Early screening for these behaviors may support prevention strategies, particularly among young adults exposed to elevated levels of stress. Full article

Background: A critical review of the literature demonstrates that masticatory apparatus with an artificial oral environment is of interest in the fields including (i) dental science; (ii) food science; (iii) the pharmaceutical industries for drug release. However, apparatus that closely mimics human chewing and oral conditions has yet to be realised. This study investigates the vital role of dental morphology and form–function connections using two-bite test parameters for effective drug release from medicated chewing gum (MCG) and compares them to human chewing efficiency with the aid of a humanoid chewing robot and a bionics product lifecycle management (PLM) framework with built-in reverse biomimetics—both developed by the first author. Methods: A novel, bio-engineered two-bite testbed is created for two testing machines with compression and torsion capabilities to conduct two-bite tests for evaluating the mechanical properties of MCGs. Results: Experimental studies are conducted to investigate the relationship between biting force and crushing/shearing and understand chewing efficiency and effective mastication. This is with respect to mechanochemistry and power stroke for disrupting mechanical bonds releasing the active pharmaceutical ingredients (APIs) of MCGs. The manuscript discusses the effect and the critical role that jaw physiology, dental morphology, the Bennett angle of mandible (BA) and the Frankfort-mandibular plane angle (FMA) on two-bite test parameters when FMA = 0, 25 or 29.1 and BA = 0 or 8. Conclusions: The impact on other scientific fields is also explored. Full article

Study design: The advent of the Matrix Wave^TM System (Depuy-Synthes)—a bone-anchored Mandibulo-Maxillary Fixation (MMF) System—merits closer consideration because of its peculiarities. Objective: This study alludes to two preliminary stages in the evolution of the Matrix Wave^TM MMF System and details its technical and functional features. Results: The Matrix Wave^TM System (MWS) is characterized by a smoothed square-shaped Titanium rod profile with a flexible undulating geometry distinct from the flat plate framework in Erich arch bars. Single MWS segments are Omega-shaped and carry a tie-up cleat for interarch linkage to the opposite jaw. The ends at the throughs of each MWS segment are equipped with threaded screw holes to receive locking screws for attachment to underlying mandibular or maxillary bone. An MWS can be partitioned into segments of various length from single Omega-shaped elements over incremental chains of interconnected units up to a horseshoe-shaped bracing of the dental arches. The sinus wave design of each segment allows for stretch, compression and torque movements. So, the entire MWS device can conform to distinctive spatial anatomic relationships. Displaced fragments can be reduced by in-situ-bending of the screw-fixated MWS/Omega segments to obtain accurate realignment of the jaw fragments for the best possible occlusion. Conclusion: The Matrix Wave^TM MMF System is an easy-to-apply modular MMF system that can be assembled according to individual demands. Its versatility allows to address most facial fracture scenarios in adults. The option of “omnidirectional” in-situ-bending provides a distinctive feature not found in alternate MMF solutions. Full article

In this study, a scaffold was designed using 3-Matic software 12.0 (Materialise, Leuven, Belgium) and fabricated via Digital Light Processing (DLP) 3D printing technology, followed by a mechanical property evaluation. The scaffold was bilaterally implanted into mandibular bone defect models in four Beagle dogs to facilitate guided alveolar bone regeneration. After 12 weeks, samples were harvested from two dogs for radiographic and histopathological evaluations. In the remaining two dogs, two dental implants were placed into the scaffold sites. After an additional 12 weeks, samples were harvested for further radiographic and histopathological assessments. (1) Compression testing of the scaffold demonstrated a compressive strength of 24.77 ± 2.36 MPa. (2) Three of the implantation sites exhibited poor wound healing and exposure of the bone grafts early post-surgery (4 weeks), with an exposure rate of 37.5%. (3) Micro-CT imaging revealed a uniform distribution of newly formed bone within the scaffold, with an average bone height of 4.05 ± 0.55 mm and a bone volume fraction of 43.93 ± 4.68%. Histopathological analysis demonstrated the presence of vascularized tissue, non-calcified bone, and newly calcified bone within the scaffold. Additionally, newly formed calcified bone and vascularized tissue were observed at the interface between the implant and the scaffold. These findings suggest that DLP 3D-printed A-W bioactive glass scaffolds represent a promising approach for guided alveolar bone regeneration in dental implant applications. Full article

This report examines the successful recovery of a feline that presented with multiple complex fractures and dislocations involving the facial and cranial structures resulting from a traffic accident. Diagnostic CT imaging identified significant injuries, including luxation of the left temporomandibular joint (TMJ), a mandibular symphyseal fracture, a hard palate fracture, and a left orbital fracture accompanied by severe exudate within the nasal cavity, compressing the left orbit and nasal passages. Importantly, no additional injuries were detected in the thoracic or abdominal regions, facilitating a more targeted treatment plan. The management of this case required extensive surgical intervention, including open reduction of the TMJ, stabilization of the mandibular symphysis, repair of the bony palate, and partial maxillectomy. After 20 days of ICU hospitalization, the feline fully recovered. This outcome is particularly noteworthy as the combination of severe injuries observed in this case is unprecedented in the veterinary literature. Consequently, it offers critical insights into both surgical techniques and postoperative management strategies applicable to similarly complex trauma cases. The feline’s full recovery, characterized by the restoration of normal daily functions, highlights the clinical significance of pursuing multiple, complex surgical procedures in cases of severe trauma. It serves as a valuable reference for advancing the understanding and management of severe facial trauma in veterinary practice. Full article

Introduction: Mandibular complete dentures often pose challenges due to anatomical and functional limitations. Impression techniques, including functional, mucostatic, compressive, selective pressure, and neutral zone methods, play a crucial role in achieving stability and retention. In 1999, Abe introduced the Suction Effective Mandibular Complete Denture (SEMCD) technique, revolutionizing mandibular denture retention by incorporating functional extensions and achieving a peripheral seal even in the presence of mobile soft tissues. Case report: An 87-year-old male presented to a private dental clinic with the chief complaint that his current lower complete denture lacked retention and stability. Intraoral examination revealed a severely resorbed mandibular edentulous ridge with movable retromolar pads and a prominent spongy lingual area. This case report describes the integration of Abe’s concepts into a digital workflow, using a single-step intraoral scanning technique and digital design software to fabricate a mandibular denture with enhanced retention and stability. Conclusions: This approach minimizes the number of clinical steps involved, improves patient comfort, and achieves predictable outcomes, highlighting the utility of digital technologies in modern prosthodontics. Full article

Excessive mandibular growth is largely affected by genetic factors and its orthodontic management is challenging. The present study utilized histophotometry and aimed to investigate immunohistochemical alterations in rat condyles following posterior mandibular displacement using a fixed intraoral functional appliance. Seventy-two male Wistar rats were divided into two equal groups, experimental and control, each consisting of three equal subgroups. The animals were sacrificed after 30, 60, and 90 days, and their condyles were isolated and examined microscopically for potential immunohistochemical changes. Statistically significant differences in RANKL appeared at days 30 and 60, while noteworthy changes regarding TRAP were evidenced at days 30 and 90. In the experimental group, RANKL decreased statistically significantly between days 60 and 90, while in the control group, the RANKL measured significantly increased at day 90 compared to days 30 and 60 alike. In the experimental group, TRAP appeared significantly decreased at day 60 vs. 30, while at day 90 vs. 60, it was found to be significantly increased. In the control group, there were no significant changes in TRAP. Posterior mandibular displacement may cause immunohistochemical changes in the rat condylar bone, and such outcomes should be considered when planning similar procedures in humans. Full article