Search Results (470)

Background: Orthodontically driven osteogenesis (ODO) is a surgical tunnel modification of periodontally accelerated osteogenic orthodontics (PAOO), combining selective corticotomy with bone grafting in sequential and/or segmental fashion. This is a minimally invasive approach that enhances periodontal health and allows orthodontic tooth movement beyond the original alveolar envelope. Considering the lack of long-term three-dimensional data on orthodontically driven osteogenesis (ODO), this study aims to quantitatively assess the long-term stability of alveolar bone and buccal cortical thickness following ODO, using CBCT imaging. The null hypothesis is that ODO does not result in significant changes in alveolar bone volume or cortical thickness over a seven-year follow-up period. Methods: Twenty patients (13 females, 7 males; mean age 27.4 ± 5.3 years) who had undergone orthodontically driven osteogenesis (ODO) using a minimally invasive tunnel approach and segmental corticotomy protocol followed by clear aligner therapy were retrospectively evaluated. The mean follow-up period after treatment was 7 years (range: 5–15 years). Cone beam computed tomography (CBCT) scans were obtained at one year postoperatively (T1) and again at the long-term follow-up visit (T2). Buccal bone thickness measurements were taken at standardized levels (3 mm, 5 mm, and 7 mm apical to the cementoenamel junction) and compared between T1 and T2 to evaluate bone stability over time. In addition, histologic evaluation of the previously grafted area was performed in two patients: one sample was collected during an alveolar ridge augmentation procedure six months after ODO, and the other during orthognathic surgery eight months after ODO. The samples were analyzed to assess new bone formation and integration of graft material. Results: Radiographic analysis showed long term stability of the new bone support. Histologic examination showed newly formed lamellar and reticular bone. Bone marrow showed no inflammatory infiltration, and bone particles were still detectable but incorporated in the newly created bone. Conclusions: Based on these findings, ODO appears to be a promising technique that could induce stable bone osteogenesis. A larger cohort study can enhance the evidence of these promising results to popularize this technique. Full article

Background/Objectives: Vertical ridge augmentation remains a challenging procedure in alveolar bone reconstruction, with existing techniques often limited by surgical complexity, graft instability, and high resorption rates. This study evaluates the clinical and histological outcomes of a novel vertical ridge augmentation technique using a wide-head tenting pole screw (WHTPS) combined with sticky bone graft material. Methods: Five patients with vertical bone deficiencies (6–10 mm) in the maxilla or mandible underwent augmentation using a single WHTPS (rectangular or round wide-head type). Sticky bone was prepared using autologous tooth bone, allografts, or xenografts, combined with fibrin glue and covered with concentrated growth factor (CGF) membranes and/or resorbable collagen membranes. After 5–6 months of healing, the WHTPS was removed, and bone biopsies were taken for histological analysis. Results: Radiographic and histological evaluations confirmed successful ridge augmentation in all cases. Newly formed bone ranged from 21.2% to 57.5%. All patients proceeded to implant placement without complications. Radiographic, clinical, and histological assessments consistently showed that new bone formation extended up to the level of the screw head, indicating complete vertical fill of the augmented space. Histology showed well-integrated, mineralized bone with no signs of inflammation. The wide-head tenting pole screw was observed to support stable space maintenance and facilitate surgical handling and favorable outcomes in vertical ridge augmentation. Conclusions: In this case series, a single wide-head tenting pole screw appeared sufficient to maintain space and resist soft tissue pressure in wide alveolar bone defects during healing. This case series suggests that the wide-head tenting pole screw technique may be a feasible option for managing severe alveolar bone deficiencies. Full article

Aim: This retrospective observational clinical cohort study evaluated 84-month clinical and radiographic outcomes of a regenerative protocol combining autologous dentin grafts processed with the Tooth Transformer^® device and Concentrated Growth Factors (CGFs) in patients with severe maxillary atrophy undergoing sinus augmentation with simultaneous implant placement. Materials and Methods: Thirty-one patients (30–75 years) with residual crestal bone height ≥ 5 mm and requiring extraction of ≥2 molars were included. Extracted teeth were processed with the Tooth Transformer^® to obtain demineralized dentin granules (500–1000 µm), which were combined with CGFs prepared using the Medifuge MF200^® to form “sticky bone.” All patients underwent sinus lift via a lateral window approach (Hilt Tatum technique) with simultaneous placement of 98 implants (12–14 mm), which were loaded after six months. Results: At the 84-month follow-up, no implant failures or peri-implantitis were recorded. CBCT and clinical evaluations showed stable regenerated bone volume and absence of peri-implant bone resorption. All patients received fixed prostheses within six months without complications. Conclusions: The combined use of processed autologous dentin and CGFs proved to be a safe, predictable, and effective regenerative technique in cases of severe maxillary atrophy, with a 100% implant survival rate at five years. Full article

BioFlx crowns represent an innovative hybrid resin polymer-based alternative for pediatric full-coverage restorations, addressing the clinical dilemma between durable-but-unaesthetic stainless steel crowns (SSCs) and technique-sensitive zirconia crowns. This narrative review synthesizes current evidence of BioFlx crowns’ mechanical properties, clinical performance, and material characteristics through a comprehensive literature search across PubMed, Scopus, and Web of Science from August through September 2025. The search identified 18 studies comprising four randomized controlled trials, two case reports/series, and twelve in vitro studies. In vitro analyses demonstrated favorable stress distribution under physiological loads (≤311 N) with notable brand-dependent performance variations. NuSmile BioFlx exhibited greater wear than zirconia, but superior wear resistance compared to SSCs, while Kids-e-Dental BioFlx crowns demonstrated less crown wear relative to zirconia, with both brands causing less antagonist wear than zirconia. BioFlx showed intermediate fracture resistance, comparable surface roughness to SSCs but higher than zirconia, and intermediate marginal gaps. Resin cements demonstrated superior retention compared to manufacturer-recommended glass ionomer and resin-modified glass ionomer cements. Clinical studies with a 12 month follow-up demonstrated 92–98% retention rates compared to 100% for SSCs, with significantly higher patient satisfaction and reduced plaque accumulation versus SSCs. However, a failure rate of 6.7% was observed. Color change values were lower than those of zirconia crowns; however, they remained clinically unacceptable (ΔE > 3.3), and stain resistance was lower than that of SSCs. Marginal integrity remained clinically acceptable, though some anatomic form deterioration occurred over time. Case reports highlighted clinical utility in nickel-allergic patients and for masking silver diamine fluoride discoloration. BioFlx crowns represent a clinically valuable esthetic alternative in pediatric dentistry, though evidence remains limited by recent market introduction, brand-specific performance variations (NuSmile vs. Kids-e-Dental), anterior tooth applicability constraints, and contraindications in bruxism and for the Hall technique. Future randomized controlled trials with ≥2 year follow-up periods are imperative to establish long-term performance. Until such evidence emerges, BioFlx crowns represent a viable clinical option for esthetically sensitive cases and nickel-allergic patients when applied with rigorous case selection. Full article

Purpose: The study aimed to assess and compare the fracture toughness of resin-bonded fixed dental prosthesis (RBFDP) of different ceramic materials and connector parameters. Methods: Twenty extracted human incisal teeth were utilized as abutments for the RBFDP. Zirconia (Zir) and lithium disilicate (LD) were manufactured in the form of anterior cantilever RBFDPs (n = 10 per group). Each material was tested using two connector designs, with the following dimensions for height (h), base (b), and width (w): 5 (h) × 4 (b) × 1 (w) mm (n = 5), and 4 (h) × 2 (b) × 1 (w) mm (n = 5). Prostheses were computer-aided design and computer-aided manufacturing (CAD/CAM) fabricated from Zir (IPS e.max ZIRCAD prime) and LD (IPS e.max CAD). Surface pretreatment of the prosthesis was completed prior to cementation with a dual-cured resin cement (Rely-X Ultimate). The combined teeth and prostheses were subjected to thermocycling before load-to-fracture testing at 45-degrees in the center of the pontic using a universal testing machine (Shimadzu Universal Testing Machine). The types of fracture failures were observed and classified as either favorable (non-catastrophic/repairable) or unfavorable (catastrophic/non-repairable) when viewed under an electron microscope. Results: The highest fracture toughness was observed in 5 (h) × 4 (b) × 1 (w) mm for Zir, reaching 269 ± 27 N, and LD, reaching 180 ± 83 N. The lowest values were found in 4 (h) × 2 (b) × 1 (w) mm for Zir at 237 ± 52 N and LD at 116 ± 25 N. Two-way ANOVA showed the fracture strength for dimension 5 (h) × 4 (b) × 1 (w) mm was significantly higher compared to dimension 4 (h) × 2 (b) × 1 (w) mm after adjusting for the type of material (p = 0.02). One Zir sample, measuring 5 (h) × 4 (b) × 1 (w) mm, exhibited tooth fracture under applied load. Meanwhile, two LD samples of the same dimensions became decemented under load. Conclusions: RBFDPs made from Zir exhibited a pattern of higher load-to-fracture values compared to LD for all dimensions; however, this was not statistically significant. The connector parameter has a more significant influence compared to the material used to fabricate an RBFDP in the anterior region. Full article

Background: The addition of chlorhexidine in dental restorative materials is a promising strategy to reduce the recurrence of tooth decay lesions. However, the main challenge is to develop materials with antimicrobial activity in the long term. Objective: This study analyses the effect of filler type and concentration of resin composites supplemented with chlorhexidine loaded in carrier montmorillonite particles (MMT/CHX) regarding their chemical, physical, and short- and long-term antimicrobial proprieties. Materials: Experimental composites were synthesized with 0, 30, or 60% filler in two ratios, 70/30 and 80/20, of barium glass/colloidal silica, respectively, and 5 wt% MMT/CHX. Conversion was measured using near Fourier-transform infrared spectrometry. Sorption and solubility were determined by specimen weight before and after drying and immersing in water. Flexural strength (FS) and elastic modulus (E) were determined by three bending tests using a universal test machine. Chlorhexidine release was monitored for 50 days. Streptococcus mutans UA159 was used in all microbiological assays. Inhibition halo assay was performed for 12 months and, also, biofilm growth for the specimens and colony-forming unit (CFU). Remineralization assay was used on restored teeth using measurements of microhardness Knoop and CFUs. Results: Conversion, sorption, and solubility were not affected by filler type and concentration. FS and E increase with the filler concentration, independent from filler type. Chlorhexidine was significantly released for 15 days for all experimental materials, and the increase in filler concentration decreased its release. Halo inhibition was observed for a longer time (12 months) in materials with 60 wt% filler at 70/30 proportion. Also, 60 wt% filler materials, independent from the filler ratio, reduced the CFU in relation to the control group from 8 to 12 months. In the remineralization assay, besides the absence of differences in hardness among the groups, after biofilm growth, the CFU was also significantly lower in materials with 60 wt% filler. Conclusions: Materials with 60% filler, preferentially with 70% barium glass and 30% silica, and 5% MMT/CHX particles demonstrated long-term antimicrobial activity, reaching 12 months of effectiveness. Also, this formulation was associated with higher mechanical properties and similar conversion, sorption, and solubility compared to the other materials. Full article

This paper presents a comprehensive analysis of contact patterns in globoid worm gears with rectilinear axial tooth profiles. Two distinct methods are employed: a CAD-based simulation, and experimental techniques including two-sheet pressure measurement films. The CAD-based method for determining the contact pattern can be successfully applied to evaluate the form, size, and position of the contact pattern. Experimental results qualitatively confirm the theoretical predictions, although measured contact areas tend to be smaller due to incomplete filling and fabrication inaccuracies. The developed models offer reliable tools for evaluating tooth contact in worm gear design, potentially reducing prototyping costs. The proposed methods establish a solid foundation for further research and improvement of contact performance in double-enveloping worm gear systems. Full article

Objective: The aim of this study was to evaluate and compare the clinical behavior of indirect onlays/overlays made of lithium disilicate and composite resin and to investigate risk factors associated with restoration failures. Methods: 112 indirect partial coverage posterior restorations (onlays and overlays) placed in 51 adult patients between January 2014 and December 2020 were examined. The restorations were evaluated using selected FDI criteria (color match, surface gloss, anatomic form, fracture of restorative material, tooth cracks and fractures, marginal discoloration, marginal integrity and recurrence of initial pathology). The survival of the restorations was analyzed using Kaplan–Meier method. Risk factors (type of restoration, type of tooth, tooth vitality, smoking) were investigated using Cox regression analysis. Risk estimation was conducted for each evaluated criterion (p < 0.05). Results: For composite restorations, the estimated survival rate was 94.2% after 5 years, dropping to 74.3% in 7.9 years and continued falling to less than 60% after 8.2 years. On the contrary, for lithium disilicate restorations the estimated survival rate was 90.9% after 5 years, dropped to 85.2% after 5.5 years remaining stable thereafter. Lithium disilicate onlays demonstrated significantly better performance than lithium disilicate overlays. Cox regression analysis did not reveal any significant association between the survival of the indirect partial restorations and restoration material, tooth type, restoration type and history of endodontic treatment. However, smoking was found to be a statistically significant risk factor (p < 0.05). Conclusions: Lithium disilicate and composite indirect restorations exhibited comparable survival rates at the early observation period. However, lithium disilicate partial coverage restorations demonstrated more favorable clinical behavior compared to composite in the long term, with statistical significance observed in ceramic vs. composite onlays. Full article

Formed milling is one of the most commonly used methods for machining the helical surfaces of various screw rotors. The profile of a formed cutter is designed according to the profile of the helical surface, which is usually represented by discrete points. The most widely used analytical method is rather complex, and it is easy to obtain singular points. To obtain a reliable cutter profile and simplify the solution procedure, a general numerical method suited for rotors with an arbitrary tooth profile is proposed. The proposed method does not need to establish and solve the complex nonlinear contact equation and can determine the contact point accurately. Firstly, a series of intersection planes that are perpendicular to the revolving axis of the cutter is constructed. The searching of the contact points of the selected tooth curves with each intersection plane is achieved using the subdivision method. By this means, the plane–curve intersection is simplified to a straight line–curve intersection that can easily be solved via Newton iteration. Meanwhile, the machinability related to the profile of the formed cutter can also be analyzed. Two cutter profiles are used to validate the proposed method. The cutter profiles generated by the proposed method are compared with the profiles generated by the analytical method. The results indicate that the accuracy and computational efficiency increase significantly. Furthermore, the proposed method can also be applied to the design of formed grinding wheels. Full article

Changes in health, lifestyle, and medication usage significantly impact overall well-being. Aging is associated with an increased need for multiple medications, or polypharmacy. Despite extensive research on how aging and polypharmacy affect the gut microbiome, relatively little is known about their impact on the oral microbiome and how shifts there can contribute to oral and systemic disease. An initial group of 55 saliva donors was formed of individuals with stage 3 periodontal disease and well-characterized for dental decay, both factors that contribute strongly to salivary microbiome identity. Relative levels of saliva bacteria were determined by 16S rRNA amplicon sequencing. Multiple variable analysis was performed to determine taxa associated with polypharmacy after correction for dental decay, tobacco use and gender. A second group, all with stage 3 periodontal disease, over 55 years of age and controlled for caries, served as a validation set. Two differences in taxa were validated as associated with polypharmacy in the elderly group. The tooth surface commensal Corynebacterium durum was lower with polypharmacy, and the dental decay-associated Propionibacterium acidifaciens was elevated. Saliva flow rate differences did not appear to be responsible for the differences seen in these taxa. Additionally, taxa associated with caries level and gender were identified. Polypharmacy associated taxa differences are potentially directly affected by medication usage, or the ailments associated with polypharmacy, and they are strong candidates to contribute to disease in the large group of elderly with poor oral health. Full article

Objective: This study aimed to evaluate the mean age of eruption of permanent teeth and their clinical emergence sequence in a longitudinal sample of children from a multi-ethnic urban population. Methods: A total of 854 children (413 females and 441 males), aged between 4 and 13 years, were examined annually for a minimum of 4 consecutive years, as part of their annual dental screening appointment. The presence of permanent teeth was recorded at each examination. Mean and median ages, with standard deviations, of individual tooth eruption were calculated, in addition to the eruption sequence, and the analysis of the data was performed using the lognormal distribution model. Regarding the error of the method, two examiners reviewed all relevant dental screening forms, and any discrepancies were resolved through consultation with the senior author. Results: The sequence of permanent tooth eruption followed a consistent pattern across sexes, with distinct differences between the maxillary and mandibular arches. In the maxilla, eruption began with the first molar, while in the mandible, it started with the central incisor. Mandibular teeth generally erupted earlier than maxillary teeth, with girls experiencing earlier eruption than boys, with some exceptions, and prolonged eruption periods. No statistically significant differences were found in the timing of eruption between contralateral homologous teeth. Conclusions: Based on the present data, the observed sequence of tooth eruption in a multi-ethnic urban population showed similar patterns across sexes. Mandibular teeth generally erupt earlier than maxillary teeth, with girls experiencing earlier eruption than boys. Full article

Barrel tools are increasingly used in high-precision machining of free-form surfaces. However, limited studies evaluate their performance specifically on spherical geometries, where tool–surface contact characteristics differ significantly. Understanding how tool geometry and process parameters influence surface quality and cutting forces in such cases remains underexplored. This study evaluates how barrel cutter radius and varying machining parameters affect cutting forces and surface roughness when milling internal and external spherical surfaces. Machining tests were conducted on structural steel 1.1191 using two barrel cutters with different curvature radii (85 mm and 250 mm) on a 5-axis CNC machine. Feed per tooth and radial depth of cut were systematically varied. Cutting forces were measured using a dynamometer, and surface roughness was assessed using the Rz parameter, which is more sensitive to peak deviations than Ra. Novelty lies in isolating spherical surface shapes (internal vs. external) under identical path trajectories and systematically correlating tool geometry to force and surface metrics. The larger curvature tool (250 mm) consistently generated up to twice the cutting force of the smaller radius tool under equivalent conditions. External surfaces showed higher Rz values than internal ones due to less favorable contact geometry. Radial depth of the cut had a linear influence on force magnitude, while feed rate had a limited effect except at higher depths. Smaller-radius barrel tools and internal geometries are preferable for minimizing cutting forces and achieving better surface quality when machining spherical components. The aim of this paper is to determine the actual force load and surface quality when using specific cutting conditions for internal and external spherical machined surfaces. Full article

Pain following orthodontic treatment is the chief complaint of patients undergoing this form of treatment. Although the use of diode lasers has been suggested for pain reduction, the mechanism of laser-induced analgesic effects remains unclear. Neuropeptides, such as substance P (SP) and calcitonin gene-related peptide (CGRP), contribute to the transmission and maintenance of inflammatory pain. Heat shock protein (HSP) 70 plays a protective role against various stresses, including orthodontic forces. This study aimed to examine the effects of diode laser irradiation on neuropeptides and HSP 70 expression in periodontal tissues induced by experimental tooth movement (ETM). For inducing ETM for 24 h, 50 g of orthodontic force was applied using a nickel–titanium closed-coil spring to the upper left first molar and the incisors of 20 male Sprague Dawley rats (7 weeks old). The right side without ETM treatment was considered the untreated control group. In 10 rats, diode laser irradiation was performed on the buccal and palatal sides of the first molar for 90 s with a total energy of 100.8 J/cm². A near-infrared (NIR) laser with a 808 nm wavelength, 7 W peak power, 560 W average power, and 20 ms pulse width was used for the experiment. We measured the number of facial groomings and vacuous chewing movements (VCMs) in the ETM and ETM + laser groups. Immunohistochemical staining of the periodontal tissue with SP, CGRP, and HSP 70 was performed. The number of facial grooming and VCM periods significantly decreased in the ETM + laser group compared to the ETM group. Moreover, the ETM + laser group demonstrated significant suppression of SP, CGRP, and HSP 70 expression. These results suggest that the diode laser demonstrated analgesic effects on ETM-induced pain by inhibiting SP and CGRP expression, and decreased HSP 70 expression shows alleviation of cell damage. Thus, although further validation is warranted for human applications, an NIR diode laser can be used for reducing pain and neuropeptide markers during orthodontic tooth movement. Full article

Background: Charcot–Marie–Tooth disease (CMT) is a genetically and phenotypically heterogeneous hereditary neuropathy. Axonal CMT type 2 (CMT2) subtypes often exhibit overlapping clinical features, which makes molecular genetic analysis essential for accurate diagnosis and subtype differentiation. Methods: This retrospective study included five pediatric patients who presented with gait disturbance, muscle weakness, and foot deformities and were subsequently diagnosed with axonal forms of CMT. Clinical data, electrophysiological studies, neuroimaging, and genetic analyses were evaluated. Whole exome sequencing (WES) was performed in three sporadic cases, while targeted CMT gene panel testing was used for two siblings. Variants were interpreted using ACMG guidelines, supported by public databases (ClinVar, HGMD, and VarSome), and confirmed by Sanger sequencing when available. Results: All had absent deep tendon reflexes and distal muscle weakness; three had intellectual disability. One patient was found to carry a novel homozygous frameshift variant (c.2568_2569del) in the IGHMBP2 gene, consistent with CMT2S. Other variants were identified in the NEFH (CMT2CC), DYNC1H1 (CMT2O), and MPV17 (CMT2EE) genes. Notably, a previously unreported co-occurrence of MPV17 mutation and congenital heart disease was observed in one case. Conclusions: This study expands the clinical and genetic spectrum of pediatric axonal CMT and highlights the role of early physical examination and molecular diagnostics in detecting rare variants. Identification of a novel IGHMBP2 variant and unique phenotypic associations provides new insights for future genotype–phenotype correlation studies. Full article

As critical components of planetary gearboxes, gears directly affect mechanical system reliability when faults occur. Traditional feature extraction methods exhibit limitations in accurately identifying fault characteristics and achieving satisfactory diagnostic accuracy. This research is concerned with the gear of the planetary gearbox and proposes a new approach termed multi-scale wavelet packet energy entropy (MSWPEE) for extracting gear fault features. The signal is split into sub-signals at three different scale factors. Following decomposition and reconstruction using the wavelet packet algorithm, the wavelet packet energy entropy for each node is computed under different operating conditions. A feature vector is formed by combining the wavelet packet energy entropy at different scale factors. Furthermore, this study proposes a method combining multi-scale wavelet packet energy entropy with extreme learning machine (MSWPEE-ELM). The experimental findings validate the precision of this approach in extracting features and diagnosing faults in sun gears with varying degrees of tooth breakage severity. Full article