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Mandibular canine distalization plays a key role in orthodontic treatment planning, particularly in cases involving premolar extraction. A three-dimensional symmetric finite element analysis (FEA) model with bilinear periodontal ligament (PDL) properties to evaluate the combined effects of five occlusal conditions—intercuspal position (ICP), incisal clench (INC), right unilateral molar clench (RMOL), right group function (RGF), and no occlusion—and three orthodontic force levels (0.98, 1.47, and 1.96 N) on PDL biomechanics. The effects were assessed by measuring hydrostatic stress as an indicator of capillary perfusion and maximum principal strain as a mechanical signal for tissue deformation and bone remodeling stimulus. According to the FEA results, a moderate force of 1.47 N produced a relatively favorable biomechanical response under nonocclusal conditions. Intercuspal position and incisal clench conditions were associated with elevated stress and strain concentrations in the PDL. The right unilateral molar clench condition preserved load-induced bilateral symmetry, whereas the right group function condition resulted in differential left–right biomechanical responses in the PDL under asymmetric occlusal loading conditions. These findings indicate that occlusal loading is a key mechanical factor influencing the biomechanical environment during orthodontic tooth movement. FEA simulations that consider occlusal loading can provide comparative biomechanical insights that can guide the selection of orthodontic forces and identification of mechanical risks.

Objective To achieve sufficient velopharyngeal function and maxillary growth for patients with unilateral cleft lip and palate (UCLP), the authors have designed a new treatment protocol for palate closure involving early two-stage palatoplasty with modified Furlow veloplasty. Details of the surgical protocol and the outcomes of the dental occlusion of patients at 4 years of age are presented. Design and Setting This was an institutional retrospective study. Patients Seventy-two UCLP patients were divided into two groups based on their treatment protocols: patients treated using the early two-stage palatoplasty protocol (ETS group; n = 30) and patients treated using Wardill-Kilner push-back palatoplasty performed at 1 year of age (PB group; n = 42). Interventions The features of the ETS protocol are as follows: The soft palate is repaired at 12 months of age using a modified Furlow technique. The residual cleft in the hard palate is closed at 18 months of age. Lip repair is carried out at 3 months of age with a modified Millard technique for all subjects. Results The ETS group showed a significantly better occlusal condition than the PB group. The incidence of normal occlusion at the noncleft side central incisor was 7.1% in the PB group; whereas, it was 66.7% in the ETS group. Conclusion The results indicate that the early two-stage protocol is advantageous for UCLP children in attaining better dental occlusion at 4 years of age.

Objectives Occlusal splints are a mainstay in the management of temporomandibular disorders, but the mechanical influence of design and thickness variations on joint and dental structures remains unclear. This study compared the stress and strain distributions within the temporomandibular joint (TMJ) and adjacent tissues produced by Michigan (stabilization) and non-permissive splints of 3-mm and 5-mm thicknesses using finite element analysis. Materials and methods Three-dimensional models of the maxilla, mandible, teeth, periodontal ligament, and articular disc were reconstructed from the Visible Human Project dataset. Michigan and non-permissive splints were modeled with occlusal thicknesses of 3 mm and 5 mm. Functional muscle forces were applied to simulate mandibular movements, and linear static analyses were performed in OptiStruct under defined boundary conditions. Results The splint-free model showed the highest stress levels in all structures. Non-permissive splints significantly reduced mandibular stress (32.3 MPa) but increased loading on the periodontal ligament. Michigan splints resulted in lower periodontal ligament stresses and a more even stress distribution within the articular disc. Increasing splint thickness improved stress reduction only in the non-permissive model. Conclusions Occlusal splints lowered peak stresses in the TMJ and related structures. Non-permissive splints provided greater joint protection, while Michigan splints achieved a more balanced distribution of occlusal forces. Clinical relevance Splint design and thickness affect how loads are transferred through the temporomandibular system. Non-permissive splints, particularly at 5 mm, reduced joint stress but increased periodontal ligament loading. Splint selection should consider the main treatment goal, with attention to using the minimal effective thickness.

Objectives This study aimed to compare the patterns of stress distribution in a lower second premolar using three conventional occlusal loadings and two more realistic loading scenarios based on occlusal contact areas. Materials and methods The teeth of a dried modern human skull were micro-CT scanned in maximum intercuspation contact with a Viscom X8060 NDT X-ray system. A kinematic analysis of the surface contacts between antagonistic right upper and lower teeth during the power stroke was carried out in the Occlusal Fingerprint Analyser (OFA) software. Stress distribution in the lower right second premolar was analysed using three-dimensional finite element (FE) methods, considering occlusal information taken from OFA results (cases 4–5). The output was compared to that obtained by loading the tooth with a single point force (cases 1–3). Results Results for cases 1–3 differ considerable from those of cases 4–5. The latter show that tensile stresses might be concentrated in grooves and fissures of the occlusal surface, in the marginal ridges, in the disto-lingual and in the distal side of the root. Moreover, the premolar experiences high tensile stresses in the buccal aspect of the crown, supporting the idea that abfraction might be a dominant factor in the aetiology of non-carious cervical lesions. Conclusions The application of FE methods in dental biomechanics can be advanced considering individual wear patterns. Clinical relevance More realistic occlusal loadings are of importance for both new developments in prosthetic dentistry and improvements of materials for tooth restoration, as well to address open questions about the worldwide spread problem of dental failure.

Mandibular advancement splints (MAS), which protrude the lower jaw during sleep, are recognized as an effective treatment for obstructive sleep apnea (OSA) through their action of enlarging the airway space and preventing upper airway collapse. However a clinical challenge remains in preselecting patients who will respond to this form of therapy. We aimed to use computational fluid dynamics (CFD) in conjunction with patient upper airway scans to understand the upper airway response to treatment. Seven OSA patients were selected based on their varied treatment response (assessed by the apnea–hypopnoea index (AHI) on overnight polysomnography). Anatomically-accurate upper airway computational models were reconstructed from magnetic resonance images with and without MAS. CFD simulations of airflow were performed at the maximum flow rate during inspiration. A physical airway model of one patient was fabricated and the CFD method was validated against the pressure profile on the physical model. The CFD analysis clearly demonstrated effects of MAS treatment on the patient's UA airflow patterns. The CFD results indicated the lowest pressure often occurs close to the soft palate and the base of the tongue. Percentage change in the square root of airway pressure gradient with MAS (ΔΔPMax%) was found to have the strongest relationship with treatment response (ΔAHI%) in correlation analysis (r=0.976, p=0.000167). Changes in upper airway geometry alone did not significantly correlate with treatment response. We provide further support of CFD as a potential tool for prediction of treatment outcome with MAS in OSA patients without requiring patient specific flow rates.

This study carried out modeling of the contact between a pair of antagonist teeth with/without individual mouthguards with different geometric configurations. Comparisons of the stress–strain state of teeth interacting through a multilayer mouthguard EVA and multilayer mouthguards with an A-silicon interlayer were performed. The influence of the intermediate layer geometry of A-silicone in a multilayer mouthguard with an A-silicon interlayer on the stress–strain state of the human dentition was considered. The teeth geometry was obtained by computed tomography data and patient dental impressions. The contact 2D problem had a constant thickness, frictional contact deformation, and large deformations in the mouthguard. The strain–stress analysis of the biomechanical model was performed by elastoplastic stress–strain theory. Four geometric configurations of the mouthguard were considered within a wide range of functional loads varied from 50 to 300 N. The stress–strain distributions in a teeth pair during contact interaction at different levels of the physiological loads were obtained. The dependences of the maximum level of stress intensity and the plastic deformation intensity were established, and the contact parameters near the occlusion zone were considered. It was found that when using a multilayer mouthguard with an A-silicone interlayer, there is a significant decrease in the stress intensity level in the hard tissues of the teeth, more than eight and four times for the teeth of the upper and lower teeth, respectively.

Background In individuals with a unilateral cleft lip and palate, there routinely exists an abnormality of the facial skeleton in all three planes ( transverse, sagittal and coronal ) . Skeletal and facial asymmetry is pronounced in the anterior part of the maxilla with a smaller maxillary width and height on the cleft side. As a mechanical stimulant, occlusal forces and the resulting stress and strain distribution within the skeletal components lead to strain-induced bone remodeling. This study was done to observe the stress distribution pattern and displacement within the maxillary complex in a complete unilateral cleft lip and palate individual when subjected to simulated occlusal forces, using a three-dimensional finite element analysis. Material and Methods A three-dimensional finite element model of the maxillary complex of a unilateral cleft lip and palate individual was developed from sequential computed tomography scan images processed at 1-mm intervals. ANSYS™ 14.0 and MIMICS™ software were used for the same. Masseter forces of 300 N were applied at the zygomatic arch bilaterally, and occlusal loads of 100 N were applied vertically onto the framework surface at different locations to simulate occlusal loading. The displacement and von Mises stresses in different planes were studied on different nodes at various anatomical points within the maxillary complex. Results The unilateral cleft lip and palate led to a non-uniform, asymmetric stress distribution pattern within the maxillary complex: intensified on the non-cleft side and weakened on the cleft side. An asymmetric displacement pattern was noted between the cleft and non-cleft sides. Conclusions The results implied that an individual born with a complete unilateral cleft lip and palate would be expected to have an asymmetric facial development between the non-cleft and cleft sides as a result of an asymmetric occlusal loading pattern.

This study presents a predictive biomechanical modeling approach for optimizing distal implant placement in the All-on-4 treatment concept, with a focus on implant angulation and occlusal load direction. Finite Element Analysis (FEA) was integrated with Response Surface Methodology (RSM) to develop 15 simulation models based on a Central Composite Design, incorporating distal implant angulations of 15°, 30°, and 45°, and occlusal load directions in both sagittal and frontal planes (45°, 67.5°, and 90°). The maximum von Mises stress in cortical bone was selected as the response variable. Regression analysis revealed that the frontal load angle had the most significant effect on stress distribution, followed by implant angulation. The resulting second-order predictive model demonstrated a strong statistical fit (R 2 = 93.39%, adjusted R 2 = 81.49%). The lowest cortical stress (95.75 MPa) occurred at 15° implant angulation with 45° occlusal loading in both planes, whereas the highest stress (265.72 MPa) was recorded at 45° angulation with 90° frontal loading. Although reducing implant tilt generally decreases peri-implant stress, no universally optimal angle can be defined due to variability in biomechanical responses under different occlusal loading conditions. Clinically, optimizing cusp inclination and load direction in conjunction with implant positioning may enhance the biomechanical performance and long-term success of full-arch implant-supported prostheses.

Objectives: The purpose of this study was to assess the oral health status of children with cerebral palsy (CP) in Dubai, United Arab Emirates (UAE). Materials and Methods: Eighty-four CP and 125 healthy children were recruited from special needs centers and private/public schools in Dubai. A dental examination for decayed-missing-filled teeth in primary dentition (dmft)/Decayed-Missing-Filled teeth in permanent dentition (DMFT) indices, simplified oral hygiene index, calculus index (CI), and oral debris index was conducted. In addition, assessments of occlusal, dentofacial, soft tissue anomalies and erosion were conducted. Statistical analysis was conducted using SPSS for Windows, version 20.0 (SPSS Inc., Chicago, IL, USA). Results: DMFT/dmft scores were comparable in both groups. CI was significantly higher among children with CP. CP patients had a significantly higher proportion of anterior open bite, anterior spacing, Class II molar Angle malocclusion, trauma, high-arched palate, tongue thrust, lymphadenopathy, angular cheilitis, macroglossia, drooling, and erosion as compared to controls. Conclusions: The study highlighted peculiar characteristics and needs for the CP patients in Dubai, UAE.