Search Results (126)

Repairing veneer defects is the key to ensuring the quality of plywood. In order to improve the maintenance quality and material utilization efficiency during the maintenance process, this paper proposes a bidirectional maintenance method based on gear rack transmission and its related equipment. Based on the working principle, a geometric relationship model was established, which combines the structural parameters of the mold, punch, and gear system. Simultaneously, it solves the problem of motion attitude analysis of conjugate tooth profiles under non-standard meshing conditions, aiming to establish a constraint relationship between stamping motion and structural design parameters. On this basis, a constrained optimization model was developed by integrating multi-objective optimization theory to maximize maintenance efficiency. The NSGA-III algorithm is used to solve the model and obtain the Pareto front solution set. Subsequently, three optimal parameter configurations were selected for simulation analysis and experimental platform construction. The simulation and experimental results indicate that the veneer repair time ranges from 0.6 to 1.8 seconds, depending on the stamping speed. A reduction of 28 mm in die height decreases the repair time by approximately 0.1 seconds, resulting in an efficiency improvement of about 14%. The experimental results confirm the effectiveness of the proposed method in repairing veneer defects. Vibration measurements further verify the system’s stable operation under parametric modeling and optimization design. The main vibration response occurs during the meshing and disengagement phases between the gear and rack. Full article

Biomimetic restorative protocols aim to preserve natural tooth structure while enhancing restoration longevity. This in vitro study aimed to evaluate the shear bond strength (SBS) in the repair of additively and subtractively manufactured CAD/CAM materials using bulk-fill resin composites and to assess the effect of thermocycling. Forty rectangular specimens (14.5 × 7 × 3 mm) were prepared from Grandio Blocs (GB, VOCO) and VarseoSmile Crown^Plus (VS, BEGO), and thermocycled (5000 cycles, 5–55 °C, 20 s dwell time). All surfaces were roughened with 50 μm Al₂O₃. Samples were repaired using VisCalor (VCB, VOCO) and Charisma Bulk Flow One (CBO, Kulzer) composites (n = 10 per group) with their respective adhesives. Each group was further divided into immediate and post-thermocycling subgroups. All specimens were tested under shear force until failure, and failure types were examined under a stereomicroscope. Representative samples were examined by SEM to evaluate filler morphology. Statistical analysis was performed with SPSS v23 (p < 0.05). No statistically significant differences in SBS were found between groups (p > 0.05). Mean SBS values were highest in VS-CBO and lowest in GB-CBO. Cohesive failures were more frequent in immediate groups, while adhesive failures predominated after thermocycling. Bulk-fill composites did not influence the repair bond strength of indirect materials. Thermocycling affected the failure type, though not the SBS values. Full article

Background/Objectives: Avulsion is a major cause of tooth loss, and its treatment involves replantation. This study analyzed the repair process of incisive teeth subjected to delayed replantation after topical treatment with ampicillin and tetracycline. Methods: Forty male rats were equally divided into four groups: immediate replantation (IM), ampicillin (AM), tetracycline (TR), and dry medium (SE). In the IM group, replantation was performed 5 min after experimental avulsion, whereas in the SE group, the teeth were kept in a dry medium for 60 min. In the AM and TR groups, the teeth were stored in whole bovine milk for 60 min, and then immersed in their respective ampicillin and tetracycline solutions for 5 min. Euthanasia was performed 60 days after the experimental surgery. Histological slides were stained with Hematoxylin and Eosin for quantitative and qualitative analyses. Results: No statistically significant differences were observed among the IM, AM, and TR groups regarding the total resorption area, reattached periodontal ligament fibers, and ankylosis. However, when compared to the SE group, these groups exhibited a smaller total resorption area (IM: p = 0.005; AM: p = 0.0007; TR: p = 0.03), a larger area of periodontal ligament fibers reattachment (IM: p = 0.0002; AM: p = 0.0002; TR: p = 0.02), and a lower presence of ankylosis (IM: p = 0.005; AM: p = 0.0002; TR: p = 0.03). The AM group exhibited the smallest inflammatory resorption. Conclusions: It is concluded that, in an aseptic environment, the use of topical antibiotics such as ampicillin and tetracycline in the treatment of the root surface during replantation of teeth stored in milk is beneficial to the periodontal repair process and root resorption. Notably, ampicillin demonstrated superior efficacy in mitigating inflammatory root resorption and better periodontal ligament reattachment. Full article

Bioceramic materials for endodontic treatments have gradually transformed over the years into materials with enhanced biocompatibility and chemical and mechanical properties compared to earlier generations. In endodontics procedures, these materials are used as restorative material in applications such as root-end fillings, pulp capping, perforations repair, and apexification repair procedures. However, they have far from ideal mechanical and handling properties, biocompatibility issues, aesthetic concerns due to tooth discolouration, limited antibacterial activity, and affordability, which are amongst several key limitations. Notably, bioceramic materials are popular due to their biocompatibility, sealing ability, and durability, consequently surpassing traditional materials such as gutta-percha and zinc oxide–eugenol sealers. A lack of recent advancements in the field, combined with nanomaterials, has improved the formulations of these materials to overcome these limitations. The existing literature emphasises the benefits of bioceramics while underreporting their poor mechanical properties, handling difficulties, cost, and various other drawbacks. The key gaps identified in the literature are the insufficient coverage of emerging materials, narrow scope, limited insights into future developments, and underreporting of failures and complications of the existing materials. Consequently, this review aims to highlight the key limitations of various endodontic materials, primarily focusing on calcium silicate, calcium phosphate, and bioactive glass-based materials, which are the most abundantly used materials in dentistry. Based on the literature, bioceramic materials in endodontics have significantly improved over recent years, with different combinations of materials and technology compared to earlier generations while preserving many of their original properties, with some having affordable costs. This review also identified key innovations that could shape the future of endodontic materials, highlighting the ongoing evolution and advancements in endodontic treatments. Full article

With increasing life expectancy and an aging population, the demand for dental treatments that preserve natural teeth has grown significantly. Among these treatments, endodontic therapies for pulpitis and apical periodontitis play a vital role, not only in keeping occlusal function, but also in preventing the exacerbation of systemic diseases. Both pulpitis and apical periodontitis are primarily caused by infections of the oral pathobiont within the root canal, leading to inflammation and destruction of the pulp, apical periodontal tissue, and bone. Standard root canal therapy aims to remove the infection source and facilitate natural tissue healing through the body’s regenerative capacity. However, challenges remain, including limited tooth functionality after complete pulp removal in pulpitis and insufficient recovery of the large bone defect in apical periodontitis. To address these limitations, endodontic regenerative therapies have emerged as promising alternatives. Pulp regeneration therapy seeks to restore the functionality of dental pulp, while bone regeneration therapy aims to repair and regenerate large bone defects affected by apical periodontal tissue. Full article

A new type of glass fiber (GF)-reinforced bio-derived polybenzoxazine (GF/bio-derived PBz) composites suitable for dental post applications was developed. The study assessed the effects of different quantities of GF on the mechanical and thermal characteristics, thermal stability, and flame resistance of the composite samples. Additionally, the feasibility of using GF/bio-derived PBz composites for dental posts was analyzed through finite element analysis (FEA). The stress distribution in a tooth model repaired with the newly developed GF/bio-derived PBz composite posts under oblique loads was compared to models repaired with conventional glass fiber post and gold alloy post. The incorporation of GFs significantly enhanced the flexural properties, thermal stability, and flame resistance of the composite samples, while also reducing thermal expansion in a manner that closely matched that of dentin. The FEA of a tooth model repaired with a composite post derived from GF/bio-based PBz revealed a stress distribution pattern comparable to that of a tooth model repaired using a conventional glass fiber post. Considering the composite’s mechanical properties, thermal stability, flame resistance, and its suitability for dental fiber posts as demonstrated by the FEA, the GF/bio-derived PBz holds significant promise for use in dental fiber post applications. Full article

Laser cladding faces several challenges, including cracking, fracture, deformation, and interlayer delamination, which hinder its widespread application in part repair. Residual stress within the workpiece is a key factor contributing to these issues. To enhance the quality of laser cladding gear tooth repairs, the study integrates numerical modeling and experimental approaches to examine how varying annealing temperatures influence the residual stress and microstructural changes in Ni60A cladding layers. A theoretical model was established to simulate the laser cladding process and the subsequent annealing treatment utilized in gear repairs. The model was used to study the variations in temperature and stress fields at different annealing temperatures, analyze the effect of temperature gradient on residual stress, and examine the distribution of residual stress. Cladding experiments were then performed under various annealing conditions, with hardness and residual stress measurements taken from the fifth cladding layer. The results demonstrated that residual stress in the samples significantly decreased after annealing, from 781.63 MPa (RT) to 572.24 MPa (400 °C), 494.42 MPa (600 °C), and 393.83 MPa (800 °C). This indicates that the annealing process effectively reduces the residual stress in the workpiece. The residual stress values obtained from experiments showed a deviation of less than 7% from the simulation results, confirming the accuracy of the model. The highest average microhardness of 764.39 HV_0.5 was observed at 600 °C. Microstructural analysis of the cladding layer revealed significant grain refinement after annealing, with previously aggregated phases transforming into a uniformly dispersed structure. Energy Dispersive Spectroscopy (EDS) analysis confirmed the presence of boron (B) in the annealed samples, which contributes to grain refinement and enhances the annealing effect. Full article

Dental socket repair theoretically involves a constructive inflammatory immune response, which evolves from an initial M1 prevalence to a subsequent M2 dominance. In this scenario, the MEK1/2 signaling pathway is allegedly involved in M2 polarization. This study aimed to evaluate the impact of MEK1/2 pharmacological inhibition in the local host response and repair outcome. C57Bl/6-WT 8-week-old male mice were submitted to the extraction of the right upper incisor and treated (or not, control group) with MEK1/2 inhibitor PD0325901 (10 mg/kg/24 h/IP, MEK1/2i group) and analyzed at 0, 3, 7, and 14 days using microcomputed tomography, histomorphometry, birefringence, immunohistochemistry, and PCR array analysis. The results demonstrate that MEK1/2 inhibition limits the development of M2 response over time, being associated with lower expression of M2, MSCs, and bone markers, lower levels of growth and osteogenic factors, along with a higher expression of iNOS, IL-1b, IL-6, and TNF-α, as well inflammatory chemokines, indicating a predominantly M1 pro-inflammatory environment. This modulation of local inflammatory immune response is associated with impaired bone formation as demonstrated by microtomographic and histomorphometric data. The results show that MEK1/2 inhibition delays bone repair after tooth extraction, supporting the concept that M2 macrophages are essential elements for host response regulation and proper repair. Full article

In regenerative periodontal treatment, barrier membranes restore periodontal support and aid tissue healing, but slow hard tissue regeneration can disrupt healing and cause tooth instability. This study aimed to fabricate a periodontal membrane through electrospinning poly(L-lactide-co-D, L-lactide) with varying β-tricalcium phosphate (β-TCP) percentages (0%, 10%, 30%, and 40%) treated with hyaluronic acid to enhance bone regeneration in alveolar bone defects. Their ability to promote biomimetic mineralization was characterized using field emission scanning electron microscopy (FESEM) analysis, wettability, and mechanical properties. Biocompatibility and osteogenic differentiation were evaluated by examining BMSCs’ behavior. In vivo, the PLA/β-TCP membrane’s potential to promote bone regeneration was assessed through CT imaging and histological examination. FESEM analysis revealed β-TCP agglomerations within PLA fibers, increasing tensile strength. Water contact angle measurements showed better wettability and higher cell viability after hyaluronic acid treatment, indicating non-cytotoxicity. Membranes with 10% and 30% (w/w) β-TCP significantly enhanced cellular activities, including proliferation and osteogenic differentiation. Animal tests showed a significant bone growth rate increase to 28.9% in the experimental group compared to 24.9% with the commercial product Epi-Guide after three months. Overall, PLA with 30% β-TCP optimally promoted periodontal hard tissue repair and potentially enhanced bone regeneration. Full article

Amyotrophic Lateral Sclerosis (ALS) is a complex neurodegenerative disease primarily affecting motor neurons, leading to progressive muscle atrophy and paralysis. This review explores the role of Schwann cells in ALS pathogenesis, highlighting their influence on disease progression through mechanisms involving demyelination, neuroinflammation, and impaired synaptic function. While Schwann cells have been traditionally viewed as peripheral supportive cells, especially in motor neuron disease, recent evidence indicates that they play a significant role in ALS by impacting motor neuron survival and plasticity, influencing inflammatory responses, and altering myelination processes. Furthermore, advancements in understanding Schwann cell pathology in ALS combined with lessons learned from studying Charcot–Marie–Tooth disease Type 1 (CMT1) suggest potential therapeutic strategies targeting these cells may support nerve repair and slow disease progression. Overall, this review aims to provide comprehensive insights into Schwann cell classification, physiology, and function, underscoring the critical pathological contributions of Schwann cells in ALS and suggests new avenues for targeted therapeutic interventions aimed at modulating Schwann cell function in ALS. Full article

Objectives: This work investigated the effect of bacterial nanocellulose (BNC) alone or with chemisorbed chlorhexidine or povidone-iodine on post-tooth extraction repair in rats undergoing bisphosphonate therapy. Methods: Forty Wistar rats were treated with zoledronic acid, subjected to tooth extractions and allocated into groups according to the material inserted in the post-extraction socket: (1) BNC (n = 10); (2) BNC/Iodine (n = 10); (3) BNC/Chlorhex (n = 10); (4) Control (n = 10). Maxillae were dissected and macro- and microscopically analyzed. Results: Oral lesion frequency on macroscopic examination did not differ between the groups, whereas it was larger in the BNC/Iodine group compared to the BNC/Chlorhex and Control. BNC/Chlorhex had significantly more connective tissue than did BNC but did not differ from the BNC/Iodine and Control. Epithelium, vital bone, non-vital bone, tooth fragment and inflammatory infiltrate did not significantly differ between the groups. BNC/Iodine showed greater CD31 immunostaining compared to BNC and the Control. Myeloperoxidase staining did not differ between the groups, and scanning electron microscopy analysis showed similar characteristics in all groups. Conclusions: BNC with chemisorbed povidone-iodine is associated with increased vascularization in post-extraction wounds of rats undergoing bisphosphonate therapy, whereas BNC with chemisorbed chlorhexidine improves connective tissue formation. BNC works as an effective carrier for the antiseptics tested. Full article

Dental inflammatory diseases remain a challenging clinical issue, whose causes and development are still not fully understood. During dental caries, bacteria penetrate the tooth pulp, causing pulpitis. To prevent pulp necrosis, it is crucial to promote tissue repair by recruiting immune cells, such as macrophages, able to secrete signal molecules for the pulp microenvironment and thus to recruit dental pulp stem cells (DPSCs) in the damaged site. To date, root canal therapy is the standard for dental caries, but alternative regenerative treatments are gaining attention. Complex Multifrequency Magnetoelectric Fields (CMFs) represent an interesting tool due to their potential anti-inflammatory activity. Against this background, the present work aims at investigating whether the CMF treatment might restore redox balance in a co-culture model of DPSCs and inflamed macrophages mimicking an inflammatory condition, like pulpitis. Results show that superoxide anion levels and markers related to the polarization of macrophages are modulated by the CMF treatment. In parallel, the use of CMFs discloses an impact on the odontogenic commitment of DPSCs, their immunophenotype being considerably modified. In conclusion, CMFs, by modulating the odontogenic commitment and the anti-inflammatory response of DPSCs, might represent a suitable therapeutic tool against pulpitis and, in general, towards dental inflammatory diseases. Full article

Marginal enamel fractures (MEF) are a common clinical concern in dentistry, particularly in anterior teeth. These fractures occur at the enamel margins and their etiopathogenesis involves a complex interplay of mechanical, chemical, and biological factors. The ongoing research focuses on an overview of MEF to improve the knowledge about this condition. Understanding the multifaceted nature of MEF is crucial for devising effective preventive and therapeutic strategies in contemporary restorative dentistry. Indeed, mechanical stresses, such as occlusal forces and parafunctional habits are primary contributors for MEF. Additionally, it can happen at the enamel-restoration interface due to expansion and contraction of restorative materials. Chemical degradation, including acid erosion and the breakdown of adhesive bonds, further exacerbates the vulnerability of enamel. Biological factors, such as enamel composition and the presence of micro-cracks also play a role in the development of MEF. Clinical management of MEF involves subtractive or additive techniques, repairing or replacing the compromised tooth structure using techniques to ensure the integration with the natural enamel. Full article

Background and Objectives: The purpose of this case report is to examine the management of vestibular bone fenestration during alveolar socket preservation using the Periosteal Inhibition (PI) approach. Here, for the first time, the PI technique, which has been shown to be successful in maintaining intact cortical bone, is examined in the context of a bone defect. Materials and Methods: After an atraumatic extraction of a damaged tooth, a vestibular bone fenestration was discovered in the 62-year-old male patient. To shield the defect, a non-resorbable PTFE membrane (OSSEO GUARD by Zimmer Biomet) was positioned between the mucosa and the fenestration site. A resorbable porcine gelatin sponge (SPONGOSTAN^TM) was used to achieve hemostasis, and a 5/0 PGCL absorbable suture was used to close the wound. A CBCT scan was performed, and a dental implant was inserted after 4 months. Results: After 4 months, the case demonstrated positive results, with full cortical remodeling and preservation of the original bone proportions. The fenestration completely healed, proving that the PI approach works even in the presence of bone flaws in cortical bone that is still intact. Conclusions: This is the first case report that shows that vestibular bone fenestration can be successfully treated with the PI approach. It has now been demonstrated that the procedure, which hitherto needed an undamaged cortical bone to work, can help bone abnormalities to repair completely. These results imply that the PI technique is a flexible and useful approach that provides predictable results in dental surgery for treating different types of alveolar bone abnormalities. Its use might be expanded with more study to include bone dehiscence treatment. Full article

As dental pulp contains the stem cells necessary for regeneration, the tooth should hold the intrinsic capacity for self-repair. A triphasic hybrid dental biocomposite (3HB) composed of biocompatible biopolymers to provide strength, antibacterial properties and protein-based cell support could provide a conducive microenvironment for the regeneration of dental structures. 3HB was incorporated into Mineral Trioxide Aggregate (ProRoot MTA) to construct a malleable injectable implant. Human tooth pulp cells (hDPCs) significantly increased proliferation in the presence of 3HB+MTA compared to 3HB or MTA alone. Cell viability decreased with MTA alone but increased with 3HB and 3HB+MTA. 3HB+MTA was implanted into the residual tooth of drilled Wistar rat M2 molars for up to 45 days. Stereological analysis from micro-CT images showed the volume of the tooth remaining. Histologically, regenerative pulpal architecture was seen invading 3HB. A continuous odontoblastic profile lined a deposit of dentin-like material suggesting reparative dentinogenesis. Overall, no infection or encapsulation was seen. Immunohistochemically, odontoblasts were seen along the margins of the wounded tooth undergoing repair. Mesenchymal cells (MSCs) were seen at the base of the drilled tooth and by 21 days had translocated into the implant itself. Cells stimulating remineralization were highly expressed in the tooth undergoing repair. CD146-positive MSCs were seen in the center of the implant, possibly stimulating remineralization. In conclusion, behavior of 3HB⁺ in vitro and in vivo provided a promising start as 3HB+MTA may serve as a viable regenerative scaffold for pulp regeneration; however, this should be further studied before clinical use can be considered. Full article