Search Results (46)

Background: Temporomandibular disorders (TMDs) are associated with altered masticatory muscle function and pain. Although electromyographic parameters have been extensively studied, the rate of force development (RFD) remains an underexplored biomarker in this context. Objective: Analyze the RFD differences in women diagnosed with and without TMD. As a secondary outcome, the masseter and temporalis muscle pre-activation values were compared between groups based on the biting force onset. Additionally, neuromuscular efficiency analysis was also performed. Methods: A retrospective analysis of 62 medical records (41 with TMD, 21 controls) was conducted. Electromyographic activity and bite force were measured during three 5-s maximal biting tasks using synchronized surface electromyography (sEMG) and a laboratory-grade load cell. RFD was computed from force–time curves. Muscle pre-activation was assessed based on sEMG activity immediately preceding contraction onset. Results: The TMD group showed a significantly smaller RFD (mean = 85.5 N/s) compared to controls (mean = 109.0 N/s; p = 0.03; Cohen’s d = 0.5). No significant differences were found in neuromuscular efficiency and pre-activation or post-activation levels of the masseter and temporalis muscles between groups. Conclusions: RFD distinguishes women with TMD from healthy controls and may represent a sensitive biomechanical marker of neuromuscular adaptation in TMD, although confirmatory studies are needed. The absence of neuromuscular efficiency and pre-activation differences suggests compensatory neuromuscular mechanisms. Further prospective studies are needed to validate these findings and explore clinical applications. Full article

Myofascial pain (MFP) is one of the most frequent temporomandibular disorders (TMDs), primarily affecting the masseter and temporalis muscles. Various treatment strategies have been developed, including trigger point injections (TrP) and nerve blocks. Among these, the twin block technique has recently emerged as a promising, minimally invasive approach for simultaneously anesthetizing the masseteric and anterior deep temporal nerves through a single extraoral injection. This review presents the anatomical considerations essential for the application of the twin block technique. The course, branching patterns, and relationships of the masseteric and deep temporal nerves with adjacent vascular structures are described based on the current anatomical literature. A comparison is also made of isolated nerve blocks and the twin block, highlighting procedural protocols, clinical advantages, and safety profiles. The anatomical proximity between the masseteric and deep temporal nerves supports the rationale for a single-puncture approach, which can effectively reduce muscle tone, inhibit nociceptive input, and silence multiple trigger points simultaneously. In addition to its therapeutic benefits, the twin block can serve as a diagnostic tool to differentiate muscular from joint or odontogenic pain. In conclusion, the twin block technique offers a precise and efficient method for managing masticatory myofascial pain, provided that detailed anatomical knowledge is applied to ensure procedural accuracy, a low incidence of adverse effects, and patient safety. Full article

Background/Objectives: Edentulism is a prevalent chronic condition among older adults, and conventional complete dentures remain the standard of care. However, their fabrication often involves multiple clinical sessions and operator-dependent steps that may compromise fit and comfort. Digital workflows using CAD/CAM technologies have emerged as viable alternatives, offering improved efficiency, precision, and patient-centered outcomes. This case report aims to present a fully digital workflow for maxillary complete dentures and describe clinical efficiency and patient-reported outcomes. Case Presentation: A 73-year-old edentulous male patient underwent maxillary rehabilitation using a fully digital workflow. The protocol included intraoral scanning; the design and 3D printing of a custom tray with occlusal rims; border-molded functional impressions; virtual articulation; and CAD/CAM fabrication. A digitally designed Try-In denture was 3D printed for clinical evaluation, followed by adjustments. The definitive prosthesis was milled from high-performance PMMA discs using a five-axis milling machine. The workflow reduced the number of appointments and laboratory steps. At six-month follow-up, the patient reported high satisfaction with esthetics, retention, phonetics, and masticatory performance. No significant post-delivery adjustments were required. Conclusions: This case demonstrates that fully digital workflows for maxillary complete dentures are clinically viable, providing excellent precision, patient satisfaction, and time efficiency compared to conventional methods. The reproducible protocol described may support the broader integration of CAD/CAM technologies in edentulous rehabilitation. Full article

Background: Temporomandibular disorders are a generic term referred to clinical conditions involving the jaw muscles and temporomandibular joint with multifactorial pattern and genetic background. The aim of this observational study was to investigate the correlation between craniomandibular disorders and the presence of occlusal alterations. A clinical evaluation of the occlusal and articular status of the patients was carried out, integrating the latter with the electromyographic recording the activity of the masseter and temporalis muscles. Methods: A clinical observational study on 20 adults assessed temporomandibular disorders using DC/TMD criteria, anamnesis, clinical exams, occlusal and electromyographic analyses. Occlusion was evaluated morphologically and functionally. Electromyography tested static/dynamic muscle activity. Data were statistically analyzed using t-tests and Pearson correlation (p < 0.05). Results: Electromyographic analysis revealed significant differences between subjects with and without visual correction, suggesting that visual input influences masticatory muscle activity. Correlations emerged between occlusal asymmetries and neuromuscular parameters. These findings highlight clinical implications for mandibular function, muscle symmetry, and the potential for therapeutic rebalancing through targeted interventions. Conclusions: The study demonstrates a significant correlation between visual–motor integration and masticatory muscle efficiency. It emphasizes lateralized neuromuscular activation’s influence on occlusal contact distribution. Moreover, it identifies mandibular torsion–endfeel inverse correlation as a potential diagnostic marker for craniomandibular dysfunctions via surface electromyography. 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

Background/Objectives: Temporomandibular disorders (TMDs) are a group of musculoskeletal and neuromuscular conditions involving the temporomandibular joint (TMJ), masticatory muscles, and related anatomical structures. Although magnetic resonance imaging (MRI) is considered a noninvasive and highly informative imaging modality for assessing TMJ soft tissues, few studies have examined how TMJ structural features observed on MRI findings relate to oral function and craniofacial morphology in female patients with malocclusion. To investigate the associations among TMJ structural features, oral function, and craniofacial morphology in female patients with malocclusion, using MRI findings interpreted in conjunction with a preliminary assessment based on selected components of the DC/TMDs Axis I protocol. Methods: A total of 120 female patients (mean age: 27.3 ± 10.9 years) underwent clinical examination based on DC/TMDs Axis I and MRI-based structural characterization of the TMJ. Based on the structural features identified by MRI, patients were classified into four groups for comparison: osteoarthritis (OA), bilateral disk displacement (BDD), unilateral disk displacement (UDD), and a group with Osseous Change/Disk Displacement negative (OC/DD (−)). Occlusal contact area, occlusal force, masticatory efficiency, tongue pressure, and lip pressure were measured. Lateral cephalometric analysis assessed skeletal and dental patterns. Results: OA group exhibited significantly reduced occlusal contact area (p < 0.0083, η² = 0.12) and occlusal force (p < 0.0083, η² = 0.14) compared to the OC/DD (−) group. Cephalometric analysis revealed that both OA and BDD groups had significantly larger ANB angles (OA: 5.7°, BDD: 5.2°, OC/DD (−): 3.7°; p < 0.0083, η² = 0.21) and FMA angles (OA: 32.4°, BDD: 31.8°, OC/DD (−): 29.0°; p < 0.0083, η² = 0.17) compared to the OC/DD (−) group. No significant differences were observed in masticatory efficiency, tongue pressure, or lip pressure. Conclusions: TMJ structural abnormalities detected via MRI, especially osteoarthritis, are associated with diminished oral function and skeletal Class II and high-angle features in female patients with malocclusion. Although orthodontic treatment is not intended to manage TMDs, MRI-based structural characterization—when clinically appropriate—may aid in treatment planning by identifying underlying joint conditions. Full article

In this paper, a biologically congruent parallel mechanism (PM) inspired by the masticatory system of human beings has been proposed to recreate complete chewing behaviours in three-dimensional space. The mechanism is featured by direct constraints from the base (DCFB) to its end effector at two higher kinematic pairs (HKPs), which greatly raise its topological complexity. Meanwhile, friction effects occur at HKPs and actuators, causing wear and then reducing motion accuracy. Regarding these, an inverse dynamic model that can raise the computational efficiency and the modelling fidelity is proposed, being prepared to be applied to realise accurate real-time motion and/or force control. In it, Euler parameters are employed to express the motions of the constrained end effector, and Newton–Euler’s law is applied, which can conveniently incorporate friction effects at both HKPs and actuators into the dynamic model. Numerical results show that the time consumption of the model using Euler parameters is only approximately 23% of that of the model using Euler angles, and friction effects significantly increase the model’s nonlinearity. Further, from the comparison between the models of the target PM and its counterpart free of DCFB, these constraints sharply raise the modelling complexity in terms of the transformation between Euler parameters and Euler angles in the end effector and the computational cost of inverse dynamics. Full article

Background/Objectives: This study aimed to explore the functional implications of occlusal changes during clear aligner treatment (CAT) to (a) analyze occlusal changes throughout CAT and the extent of post-treatment occlusal recovery; (b) assess the relationship between post-treatment occlusion and masticatory performance; (c) investigate whether case complexity, facial biotype, and type of malocclusion influence occlusal adaptation and functional outcomes; and (d) evaluate the presence and progression of signs or symptoms of TMDs in patients undergoing CAT. Methods: This longitudinal cohort pilot study included 42 individuals who underwent CAT. Occlusion was evaluated at three timepoints: before treatment (T0), at treatment completion (T1), and three months after with night-only aligner use (T2). Masticatory performance was assessed using a two-colored chewing gum test analyzed through colorimetric software. TMD signs/symptoms were assessed using the Diagnostic Criteria for TMD [DC/TMD]. Statistical analysis used non-parametric tests. Results: A significant decrease in occlusal contact area was observed during active CAT [p = 0.016], which partially recovered at follow-up. Individuals with normal facial proportions (normodivergent) showed more anterior contacts at T1 compared to hyperdivergent individuals [p = 0.013]. Masticatory performance remained stable between T1 and T2 [p = 0.528]. A weak negative correlation was found between posterior contact number and performance score at T1 [r = −0.378, p < 0.05], suggesting that more contacts may be linked to better chewing. No TMD signs or symptoms were detected at any timepoint. Conclusions: Although CAT temporarily reduces occlusal contact area, it does not negatively impact chewing efficiency or trigger TMD symptoms. These findings support the functional safety of CAT when treatment is properly planned and monitored. Full article

Background: Dental implants enhance masticatory efficiency in edentulous patients, yet discrepancies exist between objective assessments and patient perceptions. This study evaluated masticatory efficiency before and after implant rehabilitation using the two-color mixing test (Hue-Check Gum^®) and Viewgum^® software Version 1.4. 32-bit, correlating objective data with patient-reported outcomes. Methods: In a prospective study of 30 patients receiving implant-supported prostheses, masticatory efficiency was assessed objectively (VOH values via Viewgum^®) and subjectively (10 cm VAS). Statistical analysis included Shapiro–Wilk, paired t-tests (VAS), and Wilcoxon tests (VOH). Correlation and regression analyses examined subjective–objective relationships. Results: Significant improvements occurred post-rehabilitation. VAS scores rose from 3.46 (95% CI: 2.54–4.39) to 7.29 (6.55–8.02; p < 0.001). VOH values decreased from 0.462 (0.426–0.497) to 0.438 (0.403–0.473; p = 0.001), confirming better chewing performance. No correlation was found between VAS and VOH, pre- (p > 0.346) or post-treatment (p > 0.980). Conclusion: Implant rehabilitation improves masticatory function objectively and subjectively. However, the lack of correlation underscores the need for dual assessment in clinical practice. Future studies should explore factors influencing satisfaction and performance to optimize outcomes. Full article

Complete dentures are exposed to complex masticatory forces that may lead to material fatigue and eventual structural failure. Occlusal relationships, such as eugnathic and progenic, influence the distribution of these forces significantly. Understanding their biomechanical impact is essential for improving denture design and longevity. The aim of this study was to evaluate the mechanical behaviour of complete dentures under bite loads in eugnathic and progenic occlusal relationships, using both experimental testing and numerical simulations. The focus was placed on identifying the conditions that lead to initial damage and the patterns of stress distribution. The material properties of the denture base and artificial teeth were determined through experimental tensile and compressive testing on cylindrical PMMA specimens. The denture geometry was acquired via 3D tomography based on impressions of an edentulous patient. Experimental testing of the denture bite was conducted to determine the force thresholds at which the initial cracks occur. Numerical simulations were carried out using finite element analysis at bite loads of 100 N and 200 N in both occlusal types, incorporating the obtained material parameters. The experimental results showed that the first signs of denture damage occurred at 6400 N in eugnathic occlusion and 7010 N in progenic occlusion. The numerical simulations confirmed that, during occlusion, the pressure is redistributed across multiple contact points, with a broader distribution reducing the localised stress. This redistribution was more efficient in eugnathic occlusion, which reduced the risk of longitudinal cracking in acrylic teeth. In contrast, progenic occlusion showed higher susceptibility to fractures within the acrylic denture base, particularly between adjacent teeth. Both the experimental and numerical approaches demonstrated that occlusal relationships affect the mechanical resilience of complete dentures directly. The findings highlight that eugnathic occlusion offers biomechanical advantages in stress distribution, potentially reducing the risk of fracture. Incorporating occlusal analysis into denture design protocols can enhance clinical outcomes and improve prosthetic longevity. Full article

Background: Mandibular movement is inherently complex, involving both lateral and vertical components. In older adults, this complexity is compounded by diminished neuromuscular coordination and reduced proprioceptive feedback, often impairing effective mastication. Objectives: This study aimed to review dental literature on the influence of masticatory parameters in the formation of wear facets on acrylic resin denture teeth. Methods: A targeted literature review was conducted, analyzing peer-reviewed studies from 1991 to 2024 through PubMed and Scopus. The review focused on masticatory parameters, age-related neuromuscular adaptations, chewing patterns, and preferred-side denture tooth wear, affecting older adults using complete removable dentures. Results: Mandibular movement characteristics—particularly velocity, duration, and cycle frequency—were found to significantly influence denture tooth wear, often resulting in reduced bite force and masticatory efficiency. Contemporary denture materials demonstrated improved wear resistance, aiding in the regulation of chewing frequency and velocity. These factors are increasingly important as age-related changes impact the stomatognathic system. Notably, wear facets were most prominent on the maxillary first molars, regardless of the occlusal scheme. Conclusions: This review provided a comprehensive overview of existing research, analyzed current evidence, and offered insights into the role of masticatory function and wear characteristics in older complete denture wearers. Full article

Background: Periodontal disease is a multifactorial infectious pathology that affects dental supporting tissues, impacting the health and quality of life of patients. Assessing chewing efficiency before and after periodontal therapy is crucial to better understand its impact on the quality of life of periodontal patients. Thus, the aim of this case series study was to determine whether basic periodontal therapy improves masticatory ability and efficiency in patients with mild to moderate periodontitis. Methods: A prospective, longitudinal, case series study was carried out in 42 periodontal patients treated at the University Odontology Clinic. Masticatory efficiency before and after basic periodontal treatment was assessed using both objective (HueCheck Gum test) and subjective (Quality of Masticatory Function Questionnaire: QMFQ) methods. Results: Significant improvements (p = 0.0001) were observed in periodontal variables such as hygiene index (HI), probing depth (PD), and clinical attachment level (CAL), as well as in the initial and final QMFQ total score (p = 0.045). In addition, significant differences were found in post-treatment QMFQ scores related to parafunctional habits (p = 0.046) and facial patterns, especially in meat consumption (p = 0.042) fruit and vegetable consumption (p = 0.007, p = 0.044). The initial mean HueCheck Gum test values were 0.59 ± 0.09 and the final values were 0.61 ± 0.11. These differences were not statistically significant. Conclusions: Basic periodontal treatment does not objectively improve the masticatory efficiency of patients with mild–moderate periodontitis, evaluated by means of the test of mixing two chewing gums, but it does offer subjective improvements. Full article

The human diet is a factor for disease prevention and the extension of life expectancy. Loss of teeth can adversely affect chewing capacity, which can lead patients to modify their diet and subsequently result in a poor dietary intake. This work is conducted within the framework of an ongoing research project in the Dentistry School of Universidad de la Frontera aimed at designing a diet for patients with complete removable dental prostheses (CRDP). This study aimed to evaluate the hardness of foods in a diet designed for patients using CRDP, using texture profile analysis (TPA). TPA was used to measure the hardness of 43 foods, categorized into seven groups, dairy, animal protein, fruits, vegetables, cereals and grains, high-lipid foods, and vegetable protein, to understand their impact on masticatory performance in CRDP wearers. TPA consists of two compression cycles where the food sample is compressed until it reaches a pre-established deformation. The first force peak achieved in the first cycle is used as a measure of sample hardness. Significant differences in hardness were identified within each food group, indicating a wide spectrum of textural properties that could influence chewing behavior. These findings suggest that assessing food hardness can help tailor dietary recommendations to improve masticatory efficiency in patients with dental prostheses. Full article

Background: The reduction in joint load is a potential beneficial factor in managing osteoarthritis of the temporomandibular joint (TMJ). This paper aims to compare the effectiveness of the intramuscular injection of botulinum toxin (BTX-A) as an adjunct to TMJ arthrocentesis plus viscosupplementation with arthrocentesis plus viscosupplementation alone in the management of TMJ osteoarthritis. Methods: A pilot clinical retrospective study examined TMJ osteoarthritis treatments. Patients were divided into two groups: Group A received BTX-A injections and arthrocentesis with viscosupplementation, while Group B received only arthrocentesis with viscosupplementation. The study assessed outcomes based on mouth opening (MO), pain at rest (PR), pain at mastication (PF), and masticatory efficiency (ME) at various time points (baseline (T0), 1 week (T1), 2 weeks (T2), 3 weeks (T3), and 4 weeks (T4)) up to 2 months after treatment. Results: The study included two groups, each with five patients. Group A received five weekly sessions of arthrocentesis plus viscosupplementation and a single BTX-A injection during the first arthrocentesis appointment. Group B underwent the five-session protocol of arthrocentesis plus viscosupplementation alone. MO, PF, PR, and ME improved quickly in T2 in both groups, but the improvement was of greater importance over the following weeks and lasted longer in Group A. Conclusions: Arthrocentesis with viscosupplementation associated with BTX-A was found to be more effective than arthrocentesis alone in improving clinical outcomes. This suggests that patients with TMJ osteoarthritis and myofascial pain may benefit from reduced muscle tone and joint load. Full article

Background: A key point in assessing dental implant prosthetic joints is their mechanical strength and biological response under the masticatory loading. The aim of the present systematic review was to evaluate the marginal bone loss and prosthetic behaviour of different internal/external bi-phasic implants. Methods: Randomized Clinical Trials (RCTs) have been considered for analytic purposes. The article screening was conducted on the Pubmed/MEDLINE, EMBASE and Google Scholars databases through an electronic process. Eligibility and risk of bias assessments were conducted for an article to be included in the data process. A series of pairwise meta-regressions for continuous variables was conducted considering the mean differences and 95% CI at two different timepoints: baseline and 1-year follow-up. The meta-analysis was performed comparing the following groups: internal conical prosthetic joint with index (IC), external hexagon bone level position (EI), internal tri-channel connection bone level position (ITC), internal hexagon 1 mm below the bone level (HI), internal hexagon bone level position (HI crest), cone morse 1 mm below the bone level (CM), cone morse bone level position (CM crest) and internal octagon bone level position (IO). The following parameters were considered for descriptive data synthesis: sample size, implant manufacturer, prosthetic joint type, prosthetic complications, marginal bone loss, study outcomes. Results: A total of 247 papers were identified by the electronic screening and 241 were submitted for the full text assessment. The eligibility process excluded 209 articles, and 32 studies with a low risk of bias were considered for the qualitative synthesis and further statistical methods. At the baseline, the CM showed a more effective efficiency and reduced marginal bone loss compared to IC, EI, ITC, internal hexagon, cone morse and internal octagon (p < 0.05). CM showed the lower rate of prosthetic complications and structural device failure including abutments and joint components under the loading compared to other joint types. Conclusion: Within the limits of the present investigation, the heterogeneity, the weight of the study model considered and the inherent differences between the dental implant properties, the pure CM showed a more consistent control of marginal bone loss at short- and medium-term follow-up. Despite the low rate of cumulative complications for all joints considered, the CM abutment joints were less prone to prosthetic failure at an early and medium-term follow-up. Full article