Search Results (33)

Background/Objectives: This study aimed to investigate the association between the position of impacted mandibular third molars and the morphology of the lingual cortical bone using cone beam computed tomography (CBCT), and to determine how impaction depth and angulation influence the risk of lingual cortical perforation. Methods: CBCT scans of 120 impacted mandibular third molars from 71 adult patients were retrospectively evaluated. Teeth were classified based on Pell & Gregory’s and Winter’s classifications. Lingual cortical morphology was categorized as undercut, parallel, slanted, or round. The relationship between the root apex and the lingual plate was classified as non-contact, contact, or perforating. Linear measurements included cortical lingual bone thickness and the distance from the apex to the outer surface of the lingual cortex. Results: Lingual bone morphology showed significant associations with both impaction depth and angulation, with parallel morphology more common in deeper and more angulated impactions. Lingual cortical perforation was observed in approximately 30% of the teeth, predominantly at the apex, with horizontal and deeply impacted molars (Class II, Level C) representing the highest-risk configurations. Although cortical thickness and apex-to-cortex distance were significantly smaller in apically perforated cases, no definitive threshold could be established, and these parameters were insufficient as standalone predictors at the cementoenamel junction or mid-root levels. Conclusions: Tooth angulation and impaction depth are significant predictors of lingual bone morphology and perforation risk. CBCT imaging is therefore recommended beyond low-risk cases (Level A, Class I, vertical) to improve preoperative planning, strengthen informed consent, and guide surgical strategies aimed at minimizing complications and enhancing patient safety. Full article

Slotted roller buckets are energy dissipator structures designed to reduce the destructive power of high-velocity water flows in spillways, protecting downstream environments. This study aimed to estimate the critical role of slotted roller bucket design in downstream scour mitigation and hydraulic energy dissipation. The three-dimensional Navier–Stokes (N-St) equations were solved to simulate the jet flow over the roller bucket using CFD software. The free surface volume tracking using the volume of fluid (VOF) and non-equilibrium sediment transport equations was coupled with N-St to model the local scour downstream of the roller bucket system. Subsequently, the impact of bucket tooth lip angles, tailwater depth, and bucket radius on downstream scour were examined in a numerical 3D framework. The results showed that the 45- to 55-degree lip angle configuration significantly reduced the maximum scour depth by approximately 36%. Furthermore, the study quantified the effects of tailwater depth and bucket radius on scour dimensions and flow patterns. The optimal tailwater depth reduced scour depth by approximately 20% compared with the worst case, while variations in bucket radius led to more than a 50% difference in scour depth. We identified specific ranges for these parameters that further minimized erosion potential. The research also underscored the influence of transverse mixing on surging depth, revealing a crucial mechanism for energy dissipation. These findings contributed to a deeper understanding of the complex interplay between design parameters and scour. It offered practical insights for optimizing and operating hydraulic structures sustainably and understanding the scouring processes downstream of the dams. Full article

Background: Periodontitis is a multifactorial disease leading to the loss of clinical attachment and alveolar bone. The diagnosis of periodontitis involves a clinical examination and radiographic evaluation, including panoramic images. Panoramic radiographs are cost-effective methods widely used in periodontitis classification. The remaining bone height (RBH) is a parameter used to assess the alveolar bone level. Large language models are widely utilized in the medical sciences. ChatGPT, the leading conversational model, has recently been extended to process visual data. The aim of this study was to assess the effectiveness of the ChatGPT models 4.5, o1, o3 and o4-mini-high in RBH measurement and tooth counts in relation to dental professionals’ evaluations. Methods: The analysis was based on 10 panoramic images, from which 252, 251, 246 and 271 approximal sites were qualified for the RBH measurement (using the models 4.5, o1, o3 and o4-mini-high, respectively). Three examiners were asked to independently evaluate the RBH in approximal sites, while the tooth count was achieved by consensus. Subsequently, the results were compared with the ChatGPT outputs. Results: ChatGPT 4.5, ChatGPT o3 and ChatGPT o4-mini-high achieved substantial agreement with clinicians in the assessment of tooth counts (κ = 0.65, κ = 0.66, κ = 0.69, respectively), while ChatGPT o1 achieved moderate agreement (κ = 0.52). In the context of RBH values, the ChatGPT models consistently exhibited a positive mean bias compared with the clinicians. ChatGPT 4.5 was reported to provide the lowest bias (+12 percentage points (pp) for the distal surfaces, width of the 95% CI for limits of agreement (LoAs) ~60 pp; +11 pp for the mesial surfaces, LoA width ~54 pp). Conclusions: ChatGPT 4.5 and ChatGPT o3 show potential in the assessment of tooth counts on a panoramic radiograph; however, their present level of accuracy is insufficient for clinical use. In the current stage of development, the ChatGPT models substantially overestimated the RBH values; therefore, they are not applicable for classifying periodontal disease. Full article

Background and Objectives: Evaluating jaw augmentation procedures usually necessitates pre- and postoperative tomographic imaging. Ethical considerations emphasize minimizing radiation exposure. Given that panoramic radiographs (PR, 2D) offer a lower radiation dose compared to cone-beam CT (CBCT, 3D), this study explores the feasibility of estimating tooth root volume from PR, potentially allowing safer clinical assessments with reduced radiation exposure. Materials and Methods: To develop a mathematical approximation method, the 2D tooth root surface in PR was defined as an elliptical model and a cuboid (3D). The true root volume (mm³) was gathered from CBCTs. The missing link for tooth root volume assessment in 2D radiographs is the depth of the root (vestibulo-oral dimension). It was hypothesized that the tooth root surface and its volume are related. A correlation factor “r” corresponding to the tooth roots’ depths was then calculated. Descriptive and inferential statistics were computed (p < 0.05). Results: The mathematical model was performed on 27 molars with an average volume of 472.83 mm³ (±130.25–CBCT). The factor “r” (obtained by dividing the true root volume from CBCT by the total root surface from PR) was computed as 8.04 (±1.90). Using “r” for the volume calculation in the cuboid model, an average volume of 472.37 (±152.92) for the 27 molars was computed. These volumes did not differ significantly. Conclusions: This study demonstrates that a mathematical model using elliptical projections from panoramic radiographs reliably estimates molar root volume, yielding comparable results to CBCT while reducing radiation exposure. Full article

Tooth bleaching is a widely used esthetic treatment; however, bleaching agents can temporarily alter the surface morphology of enamel, increasing surface roughness and porosity, which may lead to increased susceptibility to discoloration. This in vitro study investigated the effectiveness of fluoride varnish in preventing immediate discoloration of bovine incisors after bleaching. Specimens were bleached with 35% hydrogen peroxide and treated with either Clinpro White Varnish (CW) or Enamelast Fluoride Varnish (EN), whereas control specimens received no treatment after bleaching. The samples were immersed in coffee for 24 h, and the color difference (ΔE₀₀) was calculated using the CIEDE2000 formula. The surface morphology of enamel was examined using SEM. The fluoride varnish groups showed significantly lower color difference values than the control group (p < 0.05), with ΔE₀₀ reduced by approximately two-thirds in both the CW and EN groups. SEM observations showed that the enamel surfaces in the varnish-treated groups exhibited reduced surface irregularities compared to the untreated group, suggesting remineralization. These results suggest that the immediate application of fluoride varnish after bleaching can effectively reduce short-term discoloration by providing physical protection and promoting remineralization. Fluoride varnish may serve as a simple and effective strategy to maintain whitening outcomes and minimize early discoloration. Full article

This paper investigates the design methodologies of pure rolling helical gear pumps with various tooth profiles, based on the active design of meshing lines. The transverse active tooth profile of a pure rolling helical gear end face is composed of various function curves at key control points. The entire transverse tooth profile consists of the active tooth profile and the Hermite curve as the tooth root transition, seamlessly connecting at the designated control points. The tooth surface is created by sweeping the entire transverse tooth profile along the pure rolling contact curves. The fundamental design parameters, tooth profile equations, tooth surface equations, and a two-dimensional fluid model for pure rolling helical gears were established. The pressure pulsation characteristics of pure rolling helical gear pumps and CBB-40 involute spur gear pumps, each with different tooth profiles, were compared under specific working pressures. This comparison encompassed the maximum effective positive and negative pressures within the meshing region, pressure fluctuations at the midpoints of both inlet and outlet pressures, and pressure fluctuations at the rear sections of the inlet and outlet pressures. The results indicated that the proposed pure rolling helical gear pump with a parabolic tooth profile exhibited 42.81% lower effective positive pressure in the meshing region compared to the involute spur gear pump, while the maximum effective negative pressure was approximately 27 times smaller than that of the involute gear pump. Specifically, the pressure pulsations in the middle and rear regions of the inlet and outlet pressure zones were reduced by 33.1%, 6.33%, 57.27%, and 69.61%, respectively, compared to the involute spur gear pump. Full article

Background: Hydrostatic pressure in the periodontal ligament (PDL) plays a critical role in orthodontic treatment, influencing tooth movement and remodeling of periodontal tissue. The relationship between alveolar cortical bone density and the risk of root resorption due to excessive stress in the PDL has not been clearly defined. Objective: This study aimed to analyze hydrostatic pressure in the periodontal ligament of the tooth roots during en-masse retraction of the maxillary incisors using temporary skeletal anchorage devices (TISADs) after the first premolar extractions, as well as during full arch retraction. Methods: A numerical model was used, varying the Young’s modulus of cortical bone from 12.5 GPa to 27.5 GPa in increments of 3.0 GPa. Extreme values for bone stiffness were derived from the literature. In all the cases analyzed, the hook height was fixed at 6 mm, and the cranial surface was constrained. Results: Doubling the stiffness of the cortical bone approximately reduced the hydrostatic pressure in the PDL by 1.5 times for both full-arch retraction and post-first premolar extraction retraction. A critical hydrostatic pressure of 4.7 kPa was exceeded in full-arch retraction for low Young’s modulus of 12.5 Gpa values at forces as low as 600 g. On the contrary, for cortical bone with a high Young’s modulus of 27.5 GPa, this critical pressure was reached only at forces around 960 g, approximately 1.6 times higher. Conclusions: The density of the alveolar cortical bone significantly influences the hydrostatic pressure in the PDL of most tooth roots during orthodontic treatment. This parameter can be a critical factor in the risk of root resorption when optimal forces are exceeded. Further research is necessary to better understand these dynamics. Individual protocols for orthodontic treatment and CBCT imaging are necessary to minimize complications in the form of root resorption. Full article

Based on the idea of a surface moving frame in differential geometry, a surface envelopment approximation method is proposed for the integrated design of point-contact tooth surfaces. This method utilizes the envelopment characteristic curve of the first tooth surface as the spline curve and adopts the local structure of the second tooth surface along a predesigned contact path as the surface interpolation condition. Through motion transformation described by the motion invariants of the first tooth surface, a conjugate motion space for the second tooth surface is fully defined by the motion invariants of the first tooth surface. This constitutes the basis of the integrated optimization design space and ensures the global optimization and machinability of the tooth surface design method. Using the experimental data of the point meshing tooth surface loading contact, the gap between the two tooth surfaces during no-load meshing is used as the design target parameter to predict and control the shape and size of the contact area under heavy load and further the symmetry requirements of the tooth surface design. Consequently, a variational inequality model for the global optimal design of the point meshing tooth surface is established. Full article

Objectives: Cleaning splints (CSs) can facilitate interdental brush (IDB) insertion and guide IDBs during cleaning movement. Cleaning efficacy with and without CSs was to be assessed and compared for a fully dentate (FD) and a partially edentulous (PE) situation. Methods: For two maxillary typodont models simulating either an FD situation or a PE situation with every second tooth missing, suitable IDBs were selected and each cleaning splint was designed and fabricated by 3D-printing. Before and after standardized cleaning, model teeth were photographed at three timepoints: (T1) clean surface, (T2) surface coated with artificial plaque, and (T3) after IDB cleaning. For each of the four test groups differing in dental status (FD, PE) and CS use (without, with), n = 10 tests/group were completed. After aligning corresponding photographs, pixel-based color difference ratios (T2-T3)/(T2-T1) were calculated. Approximal cleaning efficacy was set as the mean value over predefined regions of interest. Effects of CS use and dental status were analyzed with two-way ANOVA (α = 0.05). Results: CS use significantly improved mean approximal cleaning efficacy for the PE model (p = 0.001), whereas no difference was found with the FD model (p = 0.381). Improved cleaning efficacy with the PE model was only found in combination with a CS (factor combination model × CS use: p = 0.003). Conclusions: Cleaning splints might have the potential to improve interproximal hygiene and can be recommended for clinical use. Clinical studies should validate the results of this in vitro study and clarify if CSs could be beneficial for patients with restricted manual skills. Full article

The finishing mill is a critical link in the hot rolling process, influencing the final product’s quality, and even economic efficiency. The distribution box of the finishing mill plays a vital role in power transmission and distribution. However, harsh operating conditions can frequently lead to distribution box damage and even failure. To diagnose faults in the distribution box promptly, a fault diagnosis network model is constructed in this paper. This model combines depthwise separable convolution and Bi-LSTM. Depthwise separable convolution and Bi-LSTM can extract both spatial and temporal features from signals. This structure enables comprehensive feature extraction and fully utilizes signal information. To verify the diagnostic capability of the model, five types of data are collected and used: the pitting of tooth flank, flat-headed sleeve tooth crack, gear surface crack, gear tooth surface spalling, and normal conditions. The model achieves an accuracy of 97.46% and incorporates a lightweight design, which enhances computational efficiency. Furthermore, the model maintains approximately 90% accuracy under three noise conditions. Based on these results, the proposed model can effectively diagnose faults in the distribution box, and reduce downtime in engineering. Full article

Probiotics demonstrated effectiveness in modulating oral microbiota and improving oral health in humans and rodents. However, its effects and applications on the oral microbiota of cats remain underexplored. Twelve healthy cats were randomly assigned to a control group (CON) and a composite probiotic group (CPG) for a 42-day trial. The CPG diet included additional supplementation of Bifidobacterium animalis subsp. lactis HN019, Lactobacillus acidophilus NCFM, and Lactobacillus casei LC-11, each at approximately 1 × 10¹⁰ CFU/kg. On days 0 and 42, microbial samples were collected from the gingiva, tooth surfaces, and tongue of all cats for 16S rRNA gene sequencing. Bacteroidetes, Firmicutes, and Proteobacteria were the dominant phyla across all oral sites. The CPG treatment enriched seven genera, such as Moraxella, Actinomyces, and Frederiksenia in the gingiva. Meanwhile, Bergeyella and Streptococcus were enriched on the tooth surfaces, while Bergeyella, Flavobacterium, and Luteimonas were enriched on the tongue. Furthermore, the composite probiotic effectively suppressed eight genera, such as Bacteroides, Desulfovibrio, and Filifactor in the gingiva of CPG cats, as well as Helcococcus, Lentimicrobium, and Campylobacter on tooth surfaces, and Porphyromonas, Treponema, and Fusibacter on the tongue. These findings suggest that the composite probiotic used in this study modulates the feline oral microbiota by supporting beneficial or commensal bacteria and inhibiting oral pathogens, demonstrating potential to improve oral health in cats. Full article

In order to optimize machined surface topography, this paper presents a novel algorithm for simulating the surface topography and predicting the surface roughness of a ball-end milling process. First, a discrete workpiece model was developed using the Z-map method, and the swept surface of a cutter edge was represented using triangular approximation. The workpiece surface was updated (i.e., material removal process) using the intersection between the vertical reference line and the triangular facet under a cutting judgement. Second, the proposed algorithm was verified by comparing the simulated 3D surface topography as well as 2D surface profile and average roughness (Sa) with experimental measurements. Then, numerical simulation examples planed by the Box–Behnken design methods were carried out to investigate the Sa in the ball-end milling operation. The correlations of S_a and cutting parameters were represented by a response surface reduced quadratic model based on the ANOVA results. Finally, the feed per tooth, radial depth of cut, and tilt and lead angles were optimized for improving the machining efficiency under the Sa constraints. This study presents an effective method for simulating surface topography and predicting the Sa to optimize the cutting parameters during ball-end milling process. Full article

Titanium and its alloys are extensively applied in artificial tooth roots because of their excellent corrosion resistance, high specific strength, and low elastic modulus. However, because of their biological inertness, their surface needs to be modified to improve the osteointegration of titanium implants. The preparation of biologically active calcium–phosphorus coatings on the surface of an implant is one effective method for enhancing the likelihood of bone integration. In this study, osteoinductive peptides were extracted from oyster shells by using acetic acid. Two peptide-containing hydroxyapatite (HA) composite coatings were then prepared: one coating was prepared by hydrothermally synthesizing an HA coating in the presence of peptides (HA/P/M), and the other coating was prepared by hydrothermally synthesizing HA and then immersing the hydrothermally synthesized HA in a peptide solution (HA/P/S). Characterization results indicated that the composite HA coatings containing oyster shell-based peptides were successfully prepared on the alkali-treated pure titanium surfaces. The HA/P/M and HA/P/S composite coatings were found to exhibit excellent hydrophilicity. Protein adsorption tests confirmed that the HA/P/M and HA/P/S coatings had an approximately 2.3 times higher concentration of adsorbed proteins than the pure HA coating. Full article

Background/Aim: Tooth avulsion and delayed replantation may cause inflammatory responses and root resorption of the tooth. The aim of this study is to investigate the effect of a doxycycline-loaded nitric oxide-releasing nanomatrix (DN) gel on the delayed replantation of avulsed rat teeth, with a focus on assessing the gel’s potential to promote regeneration and inhibit complications associated with the replantation process. Materials and Methods: Twenty-four right maxillary first molars from male Sprague-Dawley rats were atraumatically extracted using sterile extraction forceps. The molars were dried for 1 h at room temperature (approximately 23 °C) and divided into four groups according to the root conditioning methods after extra-alveolar 60-min drying: Group 1, no root conditioning treatment prior to replantation; Group 2, soaking in 2% NaF solution for 5 min before replantation; Group 3, 5-min soaking in NO gel and injection of the gel into the alveolar socket; Group 4, 5-min soaking in DN gel and injection of the gel into the alveolar socket before replantation. The animals were euthanized four weeks after the operation and the specimens were evaluated histologically. Results: The use of NO gel alone showed better anti-inflammatory and periodontal effects than the control group, but it did not show a significant effect compared to the group using NaF. When using NO gel loaded with doxycycline, it showed a significant anti-inflammatory effect compared to the control group and showed a similar inhibitory effect to the group using NaF. Conclusions: Within the limits of this study, in delayed replantation situations, the control of inflammatory resorption and replacement resorption is an important factor for achieving a better prognosis of replanted teeth. Root surface treatment with DN gel decreased root resorption after delayed replantation. Full article

The evaluation of surface quality after milling still represents a challenge due to the stratified structure of wood. In this paper, the surface quality of beech wood obtained by profile milling was analyzed differentiating between tool marks, fuzzy grain, and accidental surface gaps overlapped onto the deep anatomical cavities. The samples were milled at two rotation speeds, 3308 rpm (n₁) and 6594 rpm (n₂), and two feed speeds of 6.53 m/min (v_f1) and 23.74 m/min (v_f2). After the samples were cut, approximately 600 m of beech wood were further processed before measuring the surface quality again. The surface waviness measured by Wa increased more than double when the feed speed increased from v_f1 to v_f2. Rk increased with the feed speed (with the feed per tooth, f_z, for a constant n, respectively) for n₂ by a significant 57%. An increase in the rotation speed from n₁ to n₂ has reduced Rk, but the effect was not significant. The processing quality, Rk, measured at different depths did not differ statistically, in spite of the local differences in the cutting speed. The moment of measuring the surface roughness, such as immediately after sharpening or after a working period, influenced the surface quality. After the tool processed 600 m of beech material, the surface quality improved by 30%. The statistical analysis showed that the most important factor affecting the surface quality was the feed speed (implicitly f_z, for constant n and number of cutters). Full article