Search Results (133)

Background/Objectives: Image-based finite element analysis (FEA) is increasingly used in dental biomechanics; however, its reliability is often limited by insufficient experimental benchmarking and a lack of standardized workflows. This study aimed to quantitatively benchmark a Cone beam computed tomography-based (CBCT) finite element pipeline using experimentally measured strain in restored human molars. Methods: Extracted human mandibular molars were restored using a total-etch adhesive system and bulk-fill composite resin. Specimen-specific finite element models were generated from CBCT data using a standardized segmentation and meshing workflow. Numerical simulations were compared with experimentally measured strain obtained during mechanical loading using Digital Image Correlation. Agreement between numerical and experimental data was assessed using regression analysis, Bland–Altman analysis, and equivalence testing. Results: A total of 304 spatially clustered paired measurements nested within 16 specimens were analyzed. FEM predictions showed strong correlation with experimental data (r = 0.91–0.97; R² up to 0.937) and low relative error (~5–6%). The model systematically overestimated deformation by approximately 10–15%. Equivalence was confirmed within ±15% for dentin and composite, and within ±20% for enamel. Bland–Altman analysis revealed proportional bias and heteroscedasticity, particularly in dentin. Conclusions: The proposed CBCT-based finite element workflow demonstrates strong benchmarking agreement with experimental measurements and provides reproducible estimates of mechanical behavior within defined tolerance limits under controlled experimental conditions. Despite systematic overestimation, the model exhibits stable and reproducible behavior under controlled conditions. These findings support the use of experimentally benchmarked, image-based FEA workflows in dental biomechanical research. Full article

(1) Background: Mandibular condylar fractures continue to be a subject of debate, traditionally framed as a choice between open and conservative management. However, this binary approach fails to adequately account for fracture-level anatomy, Temporomandibular joint (TMJ) involvement, and functional outcomes. (2) Purpose: To present an imaging-guided, fracture-level-based algorithm that integrates radiologic evaluation, surgical approach selection, fixation biomechanics, and functional rehabilitation. (3) Review Strategy: This invited review combines current evidence with a 13-year institutional experience involving 495 joints. High-resolution Computed Tomography (CT) Imaging was used to assess fracture morphology, displacement, and ramal height, while Magnetic Resonance Imaging (MRI) was selectively employed in intracapsular fractures to evaluate disc–condyle relationships when intra-articular involvement was suspected. Management decisions, including surgical approach and fixation strategy, were guided by an institutional algorithm tailored to fracture characteristics. (4) Results: Implementation of this approach yielded consistent and predictable outcomes. Mouth opening improved from approximately 18.77 mm preoperatively to 40 mm at 6 months. Lateral excursions became symmetrical (~9.6 mm), occlusion was restored in all patients, and bite force returned to near-physiological levels. Pain scores showed near complete resolution within 1 month. Postoperative morbidity remained low, with predominantly transient facial nerve weakness. (5) Conclusions: This imaging-guided, algorithmic framework provides reproducible functional outcomes and signifies a shift toward structured, anatomically driven management of condylar fractures. Full article

Tooth-supported fixed partial dentures (FPDs) exhibit complex biomechanical behaviour because occlusal loads are transferred through the periodontal ligament (PDL) and heterogeneous mandibular bone. This pilot study aimed to develop a patient-specific NURBS-based finite element analysis (FEA) workflow for anatomically realistic mandibular reconstruction and to evaluate the biomechanical effect of geometric simplification in tooth-supported FPD simulations. Cone beam computed tomography data from a single subject were segmented and reconstructed into a layered three-dimensional model of the mandible and dentition, including cortical bone, cancellous bone, teeth, and PDL. A high-fidelity reference model (V0) and four simplified variants (V1–V4) were analysed under static 500 N loads applied at 0° and 30°. The reference model yielded a maximum von Mises stress of 507 MPa and a peak displacement of 0.74 mm, with stress concentrations consistently localised at the retainer–pontic connector region. Inclusion of the PDL markedly affected the mechanical response, doubling denture displacement in simplified comparative models. Among the simplified configurations, V4, which preserved cortical morphology and PDL representation while omitting detailed trabecular architecture, showed the closest agreement with the reference model, with mean deviations of 6.1% and 5.8% under the two loading conditions, respectively. These findings suggest that patient-specific NURBS–FEA modelling provides a robust framework for biomechanical assessment of tooth-supported FPDs, while controlled simplification may improve computational efficiency without substantially compromising accuracy under static loading conditions. Full article

The long-term success of implant-supported prostheses (ISPs) is strongly influenced by material selection, which affects stress distribution within the implant system and surrounding cortical bone. This study aimed to assess the biomechanical behavior of a four-unit ISP supported by two implants in the posterior region, using different framework and superstructure material combinations through dynamic finite element analysis (FEA). Methods: A three-dimensional (3D) edentulous mandibular model was created using Mimics software, with two implants placed in the first premolar and second molar regions. Four framework materials—titanium (Ti), glass fiber–reinforced composite (GFRC), 3Y-TZP zirconia, and polyether ether ketone (PEEK)—were combined with two superstructure materials, 5Y-TZP zirconia and resin-matrix ceramic (RMC), forming eight groups. Dynamic loading simulated chewing forces, and stress distribution was analyzed using the von Mises criterion. Results: The results demonstrated that 3Y-TZP zirconia frameworks generated the highest stress values across implants, abutments, and cortical bone. RMC crowns consistently produced lower stress than 5Y-TZP zirconia across all the groups. PEEK showed the highest displacement, followed by GFRC, zirconia, and Ti. Conclusion: Materials with higher Young’s modulus tended to exhibit greater stress transfer to the implant, implant components, and cortical bone. In contrast, polymer-based materials may show a tendency toward greater deformation and displacement compared with metallic and ceramic materials. Full article

Background: An exaggerated curve of Spee is a common finding in malocclusions with a deep overbite and requires correction to achieve functional occlusion and long-term stability. Leveling of the curve of Spee using continuous archwire mechanics generates complex force systems, the biomechanical effects of which depend on archwire material properties, cross-sectional dimensions, and the depth of the curvature being corrected. Quantitative data describing stress distribution within the teeth and periodontal ligament during this process remain limited. Objective: To evaluate and compare the stresses generated in the mandibular teeth and periodontal ligament during leveling of the curve of Spee using orthodontic archwires of different materials and dimensions through three-dimensional finite element analysis. Materials and Methods: A three-dimensional finite element model of the mandibular dentition, periodontal ligament, and supporting alveolar bone was constructed from computed tomography data. Orthodontic brackets and archwires of stainless steel, nickel–titanium, and titanium–molybdenum alloy were modeled in four dimensions: 0.014-inch, 0.016-inch, 0.016 × 0.022-inch, and 0.019 × 0.025-inch. Leveling of the curve of Spee was simulated at incremental depths ranging from 2 mm to 6 mm using displacement-controlled activation. Von Mises stresses generated within the teeth and periodontal ligament were recorded and compared across all simulations. Results: Stress magnitudes increased with increasing depth of the curve of Spee, larger archwire dimensions, and greater wire stiffness. Stainless steel archwires produced the highest stresses, followed by titanium–molybdenum alloy, while nickel–titanium archwires consistently generated the lowest stresses in both teeth and periodontal ligament. Conclusions: Archwire material and dimension significantly influence stress generation during leveling of the curve of Spee. Flexible archwires produce lower stress levels and may be advantageous during early correction of deeper curves. Full article

This study evaluated the biomechanical effects of different attachment configurations on buccal uprighting of lingually inclined mandibular second molars using clear aligners (CAs). Finite element analysis was performed to simulate a 2° uprighting movement, with boundary conditions applied to the basal bone and loading generated through geometric mismatch between the aligner and dentition. Six experimental groups were established according to attachment placement on the first and second molars. Three-dimensional tooth displacement, crown-to-root displacement ratio (C/R ratio), moment-to-force ratio (M/F ratio), and anchorage loss were analyzed. Group 5, combining a buccal attachment on the first molar and a lingual attachment on the second molar, demonstrated the most favorable biomechanical performance, with controlled tipping (C/R ratio −1.67), minimal anchorage loss (3.2%), and an optimal M/F ratio (5.5). In contrast, Group 3 exhibited excessive anchorage loss (44.8%) and inefficient force transmission, while Group 6 showed reduced efficiency despite a high M/F ratio, indicating mechanical overconstraint. These findings suggest that attachment configuration plays a critical role in determining force–moment systems in CA therapy, and increasing attachment number does not necessarily improve treatment efficiency. Strategic placement of attachments can enhance biomechanical control and optimize clinical outcomes in mandibular second molar uprighting. Full article

The safety of mandibular anesthesia is directly dependent on a precise understanding of the spatial relationships in the pterygomandibular space, particularly the risk of injury to the highly vascularized pterygoid venous plexus (PVP). In vivo studies of PVP displacement during mandibular movements face significant technical challenges. Objective: The study aims to study the spatial displacements of the pterygoid venous plexus during various physiological positions of the mandible using computer modeling with the finite-element method (FEM). Materials and Methods: A three-dimensional finite-element model was developed based on computed tomography data and the BodyParts3D anatomical atlas. The model included the bony structures of the skull, mandible, temporomandibular joint, masticatory muscles, and blood vessels. Simulations were performed for vertical displacements of the jaw at 15, 25, and 35 mm, as well as horizontal displacements of 5 mm to the left and right. Results: It was found that the magnitude of PVP displacement is proportional to the degree of mouth opening. The maximum total displacement (1.24 mm) was recorded at a 35 mm opening along the “posterior–medial–inferior” vector. Lateral excursions revealed asymmetry: displacement to the right caused plexus movement posteriorly, medially, and inferiorly (0.66 mm), while displacement to the left resulted in movement anteriorly, laterally, and superiorly (0.64 mm). Conclusions: This study demonstrates the significant mobility of the pterygoid venous plexus, which depends on the direction and amplitude of mandibular movements. The obtained data have important practical implications for planning regional anesthesia and minimizing the risk of iatrogenic complications. From a biomechanical perspective, maximum mouth opening produces the greatest displacement of the PVP, which may hypothetically reduce the risk of vascular puncture. Clinical studies are required to confirm this. Full article

Background: The majority of Class II malocclusions stem from mandibular deficiency, leading to chin retrusion. In growing patients, the ideal correction—aiming for a skeletal mandibular response—should avoid common pitfalls such as “Point B” dropping postero-inferiorly, excessive labial proclination of mandibular incisors, or the lingual tipping and extrusion of maxillary incisors. When planning mandibular advancement (MA) using clear aligners with integrated advancement features, biomechanical forces are not the only consideration; precise management of the lower incisor position is critical for success. Current literature highlights not a good control in digital planning software: these platforms are primarily dentoalveolar-based and lack integrated cephalometric analysis. Consequently, mandibular advancement is often defined by standard linear parameters (typically 2 mm per step), while incisor position is managed through virtual alignment without correlation to cephalometric landmarks like the Pogonion, NB line, or IMPA. The software cannot monitor real-time sagittal or vertical skeletal relationships, the software will elaborate the treatment planning after doctor’s prescription, the clinician must manually adjust incisor positioning based on external cephalometric analysis to prevent dental compensation or excessive proclination. Aim: This clinical case demonstrates a specific arch preparation protocol designed to optimize mandibular advancement in a growing patient with mandibular retrusion. Methods: A 12-year-old female presented with a skeletal and dental Class II malocclusion, characterized by increased overjet and a normal overbite. Treatment was conducted using Invisalign^® clear aligners (22 h/day wear, weekly changes). The treatment objectives were: transverse: Correct upper dentoalveolar contraction and coordinate arch form while restoring midline alignment; sagittal: establish Class I molar and canine relationships by correcting the overjet and reducing the labial inclination of the lower incisors; vertical: level the curve of Spee. A key clinical condition of our protocol was the pre-advancement phase: the lower arch was reshaped by reducing the buccolingual inclination (retroclination) and intruding the lower incisors. This was specifically intended to increase the available overjet space, creating the necessary room for subsequent mandibular advancement. Results Treatment was completed in 24 months with high patient compliance. Objectives were successfully met, including the correction of skeletal and dental discrepancies, the establishment of harmonious arch forms, and precise overjet reduction through enhanced control of the mandibular incisors. Conclusions: This case report outlines an optimized clinical strategy for Class II correction. Cephalometric Integration: Perform an initial analysis outside the digital planning software to define the ideal IMPA and NB angles. Anatomic Verification: Utilize radiographic overlays to ensure tooth movement remains within alveolar bone limits. Pre-MA Optimization: Prioritize a “pre-advancement” phase to maximize the sagittal inter-arch space (overjet). A larger overjet allows for a more significant orthopedic effect from the MA features. Stepwise Advancement: Implement mandibular advancement in increments (≥2 mm) with periodic clinical reassessment to facilitate the adaptation of the muscular sling and functional occlusion. Full article

Background and Objectives: Temporomandibular disorders (TMDs) are prevalent conditions affecting the temporomandibular joint and associated musculature, arising from a complex interplay of biomechanical, neuromuscular, and psychosocial factors. Increasing evidence supports functional interconnections among the TMJ, cervical spine, and shoulder girdle, suggesting that dysfunction in one region may influence others; however, these relationships remain incompletely understood. This study aimed to evaluate the association between scapulohumeral trauma, postural abnormalities, and TMDs, and to assess their evolution following interdisciplinary rehabilitation. Materials and Methods: A retrospective observational study with prospective follow-up was conducted in patients with scapulohumeral fractures associated with TMD and postural abnormalities. Postural parameters and the clinical features of temporomandibular disorders (TMDs) were evaluated at baseline and follow-up using a structured clinical assessment informed by the DC/TMD framework, together with clinical examination, electromyographic analysis, and mandibular mobility measurements. Postural evaluation was performed using digital baropodometric analysis (Free Med™ platform with FreeStep™ software, standard Medica sensor, Rome, Italy. Patients received individualized multidisciplinary treatment, including orthopaedic rehabilitation, occlusal splint therapy, physiotherapy (twice weekly), pharmacological management, and odonto-periodontal care. Statistical analyses were performed using non-parametric tests (p < 0.05). Results: Significant postural improvement was observed (p < 0.01), with the proportion of patients with normal posture increasing from 0% to 22.2% and the proportion with moderate forward lean decreasing from 53.3% to 15.6%. TMD severity decreased progressively across evaluations (Friedman χ² = 72.35, p < 0.01). No statistically significant differences were found between treatment groups with respect to postural outcomes, although descriptive differences in TMD improvement were observed at later evaluation points. Conclusions: Interdisciplinary rehabilitation was associated with significant improvements in both postural alignment and TMD severity. Scapulohumeral trauma may be associated with alterations in TMJ function and overall posture, while multimodal therapy supports functional recovery. Further randomized controlled studies are needed to confirm these findings. Full article

Background: The biomechanical behaviour of mandibular Ti-Zr mini-implant (MDI) retained overdentures is influenced by implant number, loading conditions, and mucosal thickness. This study assessed the effect of mucosal thickness and other factors on peri-implant and distal edentulous ridge microstrain values under functional loading. Methods: Eight stereolithographic mandibular models simulating D2 bone were fabricated with one, two, three, or four Ti–Zr MDIs and covered with artificial mucosa of 1.9 mm (thin) or 3.8 mm (thick). Standardized overdentures were loaded anteriorly, unilaterally, and bilaterally with forces ranging from 50 to 300 N. Strain gauges measured micro-deformation at vestibular and oral peri-implant sites and the distal edentulous ridge. Data were analyzed using MANOVA and between-subject tests, with effect sizes (η²) calculated. Results: Peri-implant microstrain decreased with increasing implant number, with single-implant overdentures reaching more than 2500 µε under anterior loading, as well as two-implant overdentures under unilateral loading; four-implant configurations remained <2000 µε. Mucosal thickness had no influence on peri-implant strains in two- and four-implant setups; however, thicker mucosa showed a very small attenuation effect in one-implant arrangements and medium effect in three-implant arrangements. Loading force and position were the dominant determinants of peri-implant strain. Distal ridge microstrain was significantly attenuated by thicker mucosa (η² ≈ 0.449). Conclusions: Implant number, loading force and position predominantly govern peri-implant strain distribution, while thicker mucosa effectively reduces distal ridge strain beneath the overdenture. Single- or two-implant mandibular overdentures are more vulnerable to high unilateral or anterior loads, emphasizing the importance of careful implant planning and occlusal management in clinical practice. Full article

Inter-implant distance (IID) is crucial for peri-implant bone preservation and long-term implant success. Traditionally, a minimum IID of 3 mm is recommended to limit marginal bone loss, although the biomechanical effect of smaller distances remains debated and may depend on multiple biological, prosthetic, and surgical factors. This study uses finite element analysis (FEA) to evaluate the effect of IID on stress distribution in peri-implant bones of D3 and D4 quality, considering crestal versus subcrestal implant placement, and interpreting results within Frost’s mechanostat theory. Implants with an internal conometric connection were modeled within simulated D3 and D4 mandibular bone blocks. IID values of 3 mm, 1.5 mm, and 1 mm were analyzed under masticatory load. Von Mises stresses in cortical and trabecular bone were compared against biomechanical thresholds (2 MPa disuse and 20 MPa remodeling limit). Results: Cortical stress increased with decreasing IID, more pronounced in crestal placement. In D3 bone, maximum cortical stress rose from 7.2 MPa (3 mm IID) to 16.5 MPa (1 mm IID) under crestal placement, while remaining within the mechanostat-based thresholds adopted in the present stress-interpretation framework. In D4 bone, cortical stress approached 20 MPa at 1 mm IID under crestal placement, indicating a less favorable mechanical condition within the interpretive framework adopted. Subcrestal placement reduced cortical stresses in both bone qualities. Trabecular stress remained stable in D3 (~1.7–8 MPa) and increased moderately in D4 (~up to 13 MPa). Conclusions: Within the limitations of this preclinical finite element study, decreasing inter-implant distance was associated with increased cortical stress, while subcrestal placement was associated with lower cortical stress than crestal placement. These findings should be interpreted only as comparative computational results, and no direct clinical conclusion can be drawn regarding the acceptability of a 1 mm inter-implant distance. Full article

The analysis of jaw kinematics is a valued approach to study the complex process of mastication. This review aims to provide a historically structured overview of methods used in jaw kinematic analysis, outlining their progression from early techniques to current technologies, and emphasizing key advances, limitations, and future directions. To address this aim, relevant literature was identified through targeted searches in academic databases, and key studies were used to trace earlier foundational work, allowing a historically oriented analysis of the field. The evolution of jaw kinematic methods reflects a progressive shift from subjective and indirect observations toward increasingly objective, dynamic, and three-dimensional assessments of mandibular movement. Despite substantial technological advances, many approaches remain limited by their complexity, cost, equipment size and lack of portability, and reliance on controlled laboratory environments, as well as constraints on natural movement. Nonetheless, these methods have contributed to clinically relevant insights into mandibular biomechanics and oral care, including the evaluation of different clinical conditions and treatment outcomes. Emerging technologies, including the development of more portable systems and improved motion tracking, together with artificial intelligence offer the potential of simplifying data acquisition under more natural conditions and its analysis enabling broader research and clinical use. Full article

Background/Objectives: The uprighting of mesially tipped mandibular second molars following first molar loss is a complex surgical and orthodontic challenge. Conventional methods often result in reciprocal anchorage loss. Mini-implants (MIs) have emerged as essential temporary anchorage devices (TADs) that provide absolute anchorage and enable more predictable tooth movements. Methods: Numerical simulations were performed to evaluate the forces required for mandibular second molar uprighting under two conditions: first, only with the second molar present, and second, with both the second and the third molars present. Although the periodontal ligament exhibits nonlinear and viscoelastic behavior in vivo, a linear elastic approximation was adopted to allow for a reliable evaluation of comparative stress distribution and initial displacement patterns within the scope of this exploratory biomechanical study. Stress distribution in the roots, periodontal ligament, and alveolar bone was assessed for each scenario. Two three-dimensional (3D) models of the left mandibular segment were created from scans of a human mandible and its teeth. The first model included the canine, the first and second premolars, and the second molar. A second model additionally incorporated the third molar. A retromolar MI was placed in both models. Molar uprighting was simulated using a spring connecting the implant to a button bonded on the mesial surface of the second molar. A force of 200 g was applied because in clinical orthodontic practice, forces that exceed approximately 2 N may cause pain or undesirable tooth mobility. Displacements along the X, Y, and Z axes, as well as regions of peak stress, were analyzed. Results: Model 1 showed maximum displacements at the furcation/mid-root, distal root apex, and distal crown, with von Mises stresses of 0.470 to 0.371 MPa. In Model 2, peak displacements occurred at the mesial root and crown, with stresses of 0.185 and 0.149 MPa, respectively. The magnitude of displacements was in the order of 10⁻⁵ mm. Such values represent initial mechanical responses rather than clinically observable tooth movements. However, the differences between models (e.g., the stress reduction) are expected to be clinically meaningful. Conclusions: Since clinical measurements regarding the stress distribution on teeth and surrounding tissues during orthodontic molar uprighting movements are impossible to perform, the finite element method (FEM) can offer insight into these aspects. The presence of the third molar significantly modulates the biomechanics of second molar uprighting via retromolar MIs. When the third molar is present, the second molar exhibits a reduced tendency for deformation during distalization, although this leads to a slower displacement. This FEM provides biomechanical insights but does not support direct clinical decision-making. The present findings should be viewed as theoretical biomechanical tendencies that require confirmation through clinical, experimental, and longitudinal studies before translation into clinical practice. Full article

Background: Mandibular fractures constitute a significant proportion of maxillofacial trauma resulting from traffic accidents and present valuable information about the severity of the trauma mechanism. The aim of this study was to evaluate the demographic characteristics, fracture patterns, and accompanying injuries of mandibular fractures resulting from traffic accidents. Methods: A retrospective examination was made of 94 patients who presented for forensic medicine evaluation following a traffic accident between 1 January 2019 and 31 December 2024 and were determined with mandibular fracture. The demographic data, accident characteristics, localization of the mandibular fracture, number of fractures, displacement status, and accompanying injuries were analyzed. Results: The analyzed cases comprised 68.1% males and 31.9% females, with a mean age of 29.27 ± 14.34 years. The mandibular fractures were displaced in 52.1% of cases, and closed in 98.9%. The fracture regions were determined to most often be the ramus (32.9%) and the condyle (32.9%). A single fracture was present in 54.9% of cases and multiple fractures in 45.1%. A significant correlation was seen between ramus fractures and male gender, driver status, and concomitant systemic injuries, whereas no significant relationship was found between some fracture types and the demographic and accident-related variables. Conclusions: Mandibular fractures resulting from traffic accidents may represent relatively high-energy trauma mechanisms, and certain fracture patterns may occur together with multiple and systemic injuries. The localization and characteristics of mandibular fractures present important clues about the biomechanics of the trauma and a holistic approach is required in the forensic medicine evaluation. Full article

Background: Closing extraction spaces with clear aligners remains a significant biomechanical challenge, frequently involving difficulties in sagittal control, torque expression, and intra-arch anchorage. Although various sequential or phased retraction strategies exist, the Caterpillar Motion protocol has not yet been formally defined. This clinical report describes the Caterpillar Motion staging protocol and illustrates its application through representative extraction cases, rather than providing a systematic review or experimental comparison. Case Presentation: Two adult patients with extraction-based malocclusions were treated using the Caterpillar Motion staging protocol. Case 1 involved bimaxillary first-premolar extractions with maximum anchorage requirements and periodontal limitations in the mandibular incisors. Case 2 presented as a full Class II malocclusion requiring maxillary first-premolar extractions with moderate anchorage for sagittal camouflage. In both cases, tooth movement was organized into alternating functional groups, with waves limited to 2 mm of sagittal closure. Discussion: The Caterpillar Motion protocol reduces the risk of aligner bowing effect, increases effective crown engagement, and redistributes anchorage demands by preventing simultaneous shortening of both arch extremities. Both cases demonstrated controlled anterior retraction, stable posterior anchorage, and favorable root parallelism. Conclusions: Caterpillar Motion offers a biomechanically coherent and clinically reproducible staging strategy for clear aligner extraction therapy. Further controlled studies are needed to validate its advantages over traditional linear and en-masse protocols. Full article