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This study establishes an empirical model for a four-flute cylindrical helical end mill, utilizing orthogonal cutting tests on a Ti-6Al-4V block as the machining workpiece. The reliability of the model was confirmed through a titanium alloy side milling experiment. Results demonstrate that the empirical index model for predicting the main cutting force error falls within the range of 4.19 %–10.0 %, providing an effective tool for cutting force prediction. The specific influence distribution trends of cutting parameters, including milling speed, feed per tooth, and depth of cut, on the cutting force through two-step milling of profile walled surface of titanium alloy were analyzed. The results reveal that the milling force in the first step exhibits a discernible upward trend with the increase of feed per tooth and radial depth of cut. Among the cutting parameters employed in the first step, the cutting speed exerts the most significant influence on the cutting force in the second step. [ABSTRACT FROM AUTHOR]

To address the issue of gear transmission error caused by noncircular gear backlash, enhancing the contact ratio of noncircular gears can prolong the meshing time of gear pairs, enhance the effective meshing line length, and consequently, reduce the transmission errors caused by gear backlash. Therefore, this study proposes a design method for high-contact-ratio variable-involute and incomplete variable-cycloid composite tooth profile (VIIVC-CTF). This method enhances the contact ratio of a small curvature radius pitch curve noncircular gear; derives a mathematical model for high-contact-ratio VIIVC-CTF; and analyzes the relationships of pitch curve ratio, rolling radius, and elliptical eccentricity with tooth profile shape, contact ratio, pressure angle, and curvature radius of high-contact-ratio composite tooth profile. Using a small curvature radius pitch curve noncircular gear as an example, a noncircular gear with high-contact-ratio composite tooth profile was manufactured. Tests were conducted to measure the tooth backlash and transmission ratio of the noncircular gear. Testing results showed that the tooth backlash of the high-contact-ratio composite tooth profile was smaller than that of the standard-involute tooth profile. The experimental, theoretical, and simulation values of the noncircular gear transmission ratio were consistent, validating the rationality of the design method for high-contact-ratio VIIVC-CTF. [ABSTRACT FROM AUTHOR]

Identifying the boundary between the tooth and the resin-based composite (RBC) is difficult when replacing restorations. Ultraviolet (UV) light has been reported to assist the viewer by causing the RBC to fluoresce. Using a laboratory-grade fiberoptic spectrometer, 46 RBCs were exposed to UV light from the Woodpecker O-Star curing light. The opalescence and fluorescence were measured relative to a human tooth that contained just dentin and a tooth that contained both enamel and dentin. After these quantitative measurements, 10 RBCs with large differences in light emittance were compared qualitatively to assess their brightness when exposed to UV light compared to the dentin specimen and the specimen containing both enamel and dentin. It was found that, when exposed to UV light, some of the RBCs were less bright compared to the two samples of teeth used for comparison, but most were brighter; some were up to six times brighter. The filler appears to affect the opalescence peaks, while the resin appears to affect the fluorescence peaks. It was concluded that because RBCs emit very different levels of opalescence and fluorescence, UV light from the Woodpecker O-Star cannot be relied upon to detect all brands of RBC on the tooth. The opalescence and fluorescence can also be used to detect changes in the formulation of the RBC. [ABSTRACT FROM AUTHOR]

Objectives: The objective of this review was to assess clinical trials that have examined the materials, design, and bonding of ceramic cantilevered resin‐bonded fixed dental prostheses (RBFDPs) as a potential option for replacing missing anterior teeth. The evaluation primarily focuses on the rate of restoration failure and clinical complications. Materials and Methods: A thorough search of databases including PubMed/MEDLINE, Scopus, and the Cochrane Library, was conducted. The most recent search was performed in October 2023. Clinical studies that compared ceramic cantilevered RBFDPs with double retainers or cantilevered RBFDPs using different ceramic materials or bonding systems were included. The outcome measures considered were restoration failure and complication rates. Results: Twelve studies met the eligibility criteria. The pooled data showed a statistically significant decrease in complication events when using cantilever designs compared with double retainer designs (p < 0.05); however, there were no differences found between the two designs in terms of restoration failure. The complication and failure rate of cantilever RBFDPs did not show a statistically significant difference with or without ceramic primer application before luting with phosphate monomer‐containing luting resin (p > 0.05). Conclusions: Ceramic cantilevered RBFDPs have lower complication rates compared with those with double retainers. The use of a ceramic primer prior to luting composite resin for ceramic cantilevered RBFDPs decreases the occurrence of complications and failures, although this effect was not statistically significant. Additional research is required to confirm these findings. Glass ceramic cantilever RBFDPs showed a decrease in success after 6 years, requiring ongoing monitoring, but both zirconia and glass‐infiltrated alumina cantilever RBFDPs have demonstrated durability with excellent long‐term success and survival rates for up to 10 and 15 years. Clinical Significance: Cantilever ceramic RBFDPs in the anterior region are a less invasive and valuable treatment option, providing good esthetic results. [ABSTRACT FROM AUTHOR]

Objective: This article describes a novel 3D‐printed template armed with interproximal matrices to isolate interproximal contact areas and guide injectable resin composite for consecutive closure of multiple diastema. Clinical Considerations: Among several treatment options proposed for diastema closure, direct resin composite is noninvasive and easy to repair. The "composite injection technique" has been introduced to improve time efficiency and reduce technique sensitivity for clinicians. However, in the case of multiple diastema, the overflow of excess resin materials onto the adjacent teeth during injection poses challenges for recontouring the interproximal anatomy. A 3D‐printed template with special‐designed gaps at interproximal areas was designed and fabricated based on a virtual diagnostic wax‐up. Flowable resin composite was then consecutively injected through the template to close diastemata at multiple adjacent teeth. Conclusion: This technique using a 3D‐printed template with interproximal isolation design contributed to an efficient and accurate operation for multiple anterior diastema closure. Clinical Significance: Efficient and accurate freehand buildups of composite restoration for multiple diastema are challenging in operative dentistry. The described noninvasive full digital workflow provides a predictable method to accurately recontour the multiple target restorations and reduce the chair‐side time and technical sensitivity. [ABSTRACT FROM AUTHOR]

Dinosaur fossils are commonly found in Brazilian Mesozoic strata, with teeth being frequently found in Cretaceous outcrops. Many studies have been made with the aim of reviewing the known diversity of Brazilian dinosaurs, mostly focusing solely on their palaeobiogeography. However, few tried to typify these body fossils in order to see which kinds were most prevalent in the fossil record. This study aims to count and identify all occurrences of non-avian dinosaur teeth (isolated or in situ) unearthed from Brazilian Cretaceous strata in order to objectively measure their representativity in the national fossil record. Our literature search showed that almost half of the dinosaur fossil record from the Cretaceous of Brazil is composed by teeth, those being particularly abundant in the Alcântara, Adamantina and Marília formations. Theropod teeth are more abundant in comparison to sauropod teeth, with spinosaurids, deinonychosaurs, and abelisaurids being amply found. Despite representing a large share of the Brazilian fossil record, dinosaur teeth have only recently been studied in depth, with many specimens being reassessed through the current identification methods. Other aspects besides primary taxonomic identification can also be further explored using the latest technologies on dinosaur teeth, allowing a deeper understanding of the palaeobiology of these reptiles. [ABSTRACT FROM AUTHOR]

In contemporary gear manufacturing, power skiving stands out as an efficient process. Therefore, several investigations have applied the skiving process to face gear. However, obtaining the precision of the skived tooth surface is a challenge. So, this study introduces a groundbreaking approach to enhancing face gear manufacturing productivity by addressing deviations in the spur face gear tooth surface arising from geometric and kinematic constraints in the conventional power skiving method. To overcome the limitations in traditional approaches, the development of a flexible model for calculating coefficients that adjust CNC axes' motion and modify the rack cutter was established. The modified tooth topology of the face gear can be obtained by adjusting the machine axis of the CNC machine. A sensitivity correction technique is employed to implement this flexible correction method, utilizing the Levenberg–Marquardt (LM) algorithm to determine the coefficients governing machine motion. The primary objective is to achieve the necessary normal deviations on the tooth surface of the spur face gear. The effectiveness of the proposed method is confirmed by using numerical examples featuring various predetermined target surfaces alongside corresponding machining simulations. [ABSTRACT FROM AUTHOR]

Pre-Miocene, stem odontocetes are known for their procumbent incisors and their function has been the subject of much speculation. Notable among these were Waipatia and several related taxa from New Zealand. Though some studies hypothesise the function of these teeth was for thrusting, the here described Aureia rerehua has unique teeth which might have formed a cage around small fish. These teeth, along with a weak vertex, flexible neck, and the smallest size among its relatives would make it a capable hunter in shallow waters. The addition of A. rerehua along with other taxa to phylogenetic analyses show three broad groups within taxa related to Waipatia and Otekaikea based on the divergence of the function of their teeth and the possible feeding strategies employed to catch prey. [ABSTRACT FROM AUTHOR]

The Kekenodontidae are late-surviving archaeocetes from the Late Oligocene of Southwest Pacific that includes a single-named species, Kekenodon onamata. Tohoraonepu nihokaiwaiu is a new genus and species of small body-sized kekenodontid from the upper Oligocene (Chattian) Kokoamu Greensand of Otago, South Island, New Zealand. Phylogenetic analyses recover T. nihokaiwaiu within a monophyletic Kekenodontidae, forming a clade with an unnamed provisional kekenodontid, OU 22023. Kekenodontids are recovered crownward to basilosaurids and stemward to a paraphyletic group of toothed 'mysticetes' that are excluded from Neoceti. The analyses confirm the identification of kekenodontids as the latest-diverging archaeocetes that persisted into the Late Oligocene. The holotype OU 22394 is a juvenile individual preserving several isolated heterodont teeth with characteristics of deciduous teeth, including unmineralized pulp cavities and cheek teeth with lower-lying triangular crowns that are different from all known kekenodontids. Diphyodonty is known from Eocene archaeocetes but is unknown from geologically younger toothed cetaceans, with monophyodonty being hypothesised for all Neoceti. Inferences of diphyodonty in T. nihokaiwaiu would be the first instance in Cetacea from rocks geologically younger than the Eocene and would indicate diphyodonty persisted in some Late Oligocene archaeocetes. [ABSTRACT FROM AUTHOR]

Clear aligners are popular orthodontic tools because of their relatively aesthetic appearance and convenience of use. Nevertheless, bodily tooth movements still present challenges. This study evaluated various configurations of attachments placed on the mandibular canine in terms of the efficiency of canine bodily movement and correction of tipping. A finite element model of the mandible was constructed to investigate the effects of various attachment configurations on the overall bodily movement and undesirable tipping of a mandibular canine. Canine movements were categorized into four types, namely tipping and bodily movements in the mesial and distal directions. The size and shape of the attachments were fixed, but their placement and orientation were varied. Five and seven attachment configurations were evaluated for their influence on tipping and bodily movements, respectively. Attachment configuration significantly influenced mandibular canine tipping. The mesial occlusal–distal cervical and mesial occlusal–mesial cervical configurations had notable effects on mesial tipping, and the mesial occlusal–mesial cervical configuration excelled in distal tipping by increasing strain by 33.1%. The mesial occlusal–mesial cervical attachment configuration consistently had superior efficiency in facilitating both mesial and distal bodily movements of the canine. The mesial occlusal–mesial cervical attachment configuration excelled in all four types of canine movement. Irrespective of the attachment configuration, canines tend to move overall with slight tipping due to skeletal resistance and their center of rotation. The attachment configuration is crucial to the success of clear aligner treatment and must be carefully considered in clinical practice. [ABSTRACT FROM AUTHOR]

This study investigates the feasibility of a dynamic navigation system (DNS) small field of view workflow (DNS-SFOVw) for fiber-post removal and compares its accuracy and efficiency to the conventional large field of view workflow (DNS-LFOVw). Fifty-six extracted human maxillary molars were divided into DNS-SFOVw (n = 28) and DNS-LFOVw (n = 28). The palatal canal was restored with an intraradicular RelyX fiber post and luted with RelyX Unicem; a core buildup was used. Teeth were mounted in a 3D-printed surgical jaw. A preoperative cone-beam computed tomography (CBCT) scan was taken with a 40 × 40 mm FOV for the DNS-SFOVw and a single arch CBCT scan for the DNS-LFOVw. The drilling entry point, trajectory, angle, and depth were planned in the X-guide software. The DNS registration method for the DNS-SFOVw was virtual-based registration on teeth, and the marker point-based method was used for the DNS-LFOVw. The fiber posts were drilled out under DNS guidance. A postoperative CBCT scan was taken. Three-dimensional deviations, angular deflection, number of mishaps, registration, and total operation time were calculated. The DNS-SFOVw was as accurate as DNS-LFOVw (P >.05). The DNS-LFOVw registration time was less than DNS-SFOVw (P <.05). There was no difference in the number of mishaps (P >.05). Both DNS-SFOVw and DNS-LFOVw were time-efficient, with DNS-LFOVw taking less total operational time (P <.05). Within the limitations of this in-vitro study, the DNS-SFOVw was as accurate as the DNS-LFOVw for fiberpost removal. Both DNS-LFOVw and DNS-SFOVw were time-efficient in removing fiber-posts. [ABSTRACT FROM AUTHOR]

This study aimed to compare the accuracy and operation time (OT) of robotic-assisted endodontic microsurgery (RA-EMS), dynamic navigation-guided (DN-guided) EMS, and static navigation-guided (SN-guided) EMS. Seventy-two teeth from three sets of standardized jaw models (TrueTooth, DELendo, Santa Barbara, CA) randomly assigned into 3 groups underwent osteotomy and root-end resection. Preoperative plans and postoperative cone-beam computed tomography images were imported into an accuracy analysis system and aligned based on the anatomical structures to assess accuracy. The OT was recorded from the moment the foot pedal was pressed down until the bur reached the target depth. Statistical analyses were conducted using Kruskal–Wallis and Scheirer–Ray–Hare tests, with significance set at P <.05. RA-EMS exhibited significantly higher accuracy than DN- and SN-guided EMS in terms of platform, angular, and resection angular deviations (P <.05). Additionally, RA-EMS exhibited significantly higher accuracy than DN-guided EMS in resection length deviation (P <.05). Significant differences were also observed in OTs between the 3 approaches, with SN-guided EMS showing the shortest OT, followed by RA-EMS and DN-guided EMS. Differences in jaw types within the DN-guided EMS group were observed in terms of angular deviation (P <.05). All 3 treatment approaches demonstrated acceptable clinical accuracy and OT. RA-EMS exhibited superior accuracy, suggesting its potential application prospects in endodontics. Further high-quality clinical studies are warranted. [ABSTRACT FROM AUTHOR]

Copyright of China Mechanical Engineering is the property of Editorial Board of China Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Surfactant Detergent & Cosmetics (2097-2806) is the property of China Surfactant Detergent & Cosmetics Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The precision of the luting protocol plays a crucial role in the success and survival rate of porcelain laminate veneers (PLVs). This in vitro study aimed to evaluate the influence of different luting techniques on the positioning of PLVs through a novel, noninvasive, scanning-based technique. A total of 45 ceramic PLVs were milled and cemented on human tooth replicas. Specimens were divided into three groups of 15, each subjected to a different luting protocol: flowable composite (Group A), dual-cure resin cement (Group B), and preheated composite resin (Group C). After luting procedures, specimens were scanned, and every STL file was superimposed with the original tooth design in Geomagic Control X version 2022.1 software to assess linear (incisal, mid, cervical) and angular discrepancies. Statistical analysis was performed using one-way ANOVA, Tukey's HSD tests, and regression analysis. ANOVA results showed no statistically significant differences for incisal (F = 0.327, p = 0.723), mid (F = 0.287, p = 0.752), cervical (F = 0.191, p = 0.827), and angular (F = 0.026, p = 0.975) measurements. Tukey's HSD post hoc tests confirmed the lack of significant pairwise differences between groups. The study demonstrated that the type of luting agent used does not significantly impact the final position of PLVs. This suggests flexibility in the choice of luting agents without compromising the accuracy of PLV placement. [ABSTRACT FROM AUTHOR]

Copyright of Current Research in Dental Sciences is the property of Ataturk University Coordinatorship of Scientific Journals and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objective: This study aims to assess the expansive effects of pterygomaxillary disjunction (PMD) in surgically assisted rapid maxillary expansion (SARME) surgery using a meta‐analysis approach. Materials and Methods: The study conducted a comprehensive literature search across five databases: PubMed, Scopus, Medline, Embase, and Cochrane, adhering to the PRISMA 2020 guidelines. Dental alterations were assessed using either cone‐beam computed tomography (CBCT) or dental casts, while skeletal changes were exclusively measured from CBCT scans. We analysed the dentoskeletal changes between PMD +/− groups and conducted a within‐group comparison. The primary focus of the results was on the mean differences observed in pre‐ and post‐operative measurements. Results: Dental expansion was larger in the PMD+ group but not statistically significant. Skeletal expansion showed a significantly larger expansion in the posterior region in the PMD+ group (P =.033). Without PMD, anterior palatal expansion was significantly larger (P =.03), and the buccal tipping of posterior teeth was also significantly larger (P =.011) to achieve acceptable dental expansion outcomes. Conclusions: Both PMD +/− groups of SARME surgery can achieve satisfactory dental expansion outcomes. However, bone expansion and tooth inclination are also important factors that influence orthodontic treatment and post‐expansion stability. By reducing the bony resistance with PMD, larger posterior palatal expansion and more parallel bony expansion are observed. In contrast, without PMD, there is smaller palatal expansion and greater tooth inclination in the posterior region. This could potentially lead to compromised periodontal conditions following expansion. [ABSTRACT FROM AUTHOR]

Introduction: This study aimed to compare the efficiency of temporary anchorage devices (TADs) and fixed functional appliances (FFAs) for mandibular molar protraction. Methods: Orthodontic records of 1050 consecutively treated patients with molar protraction were screened. Thirty‐six records (22 females and 14 males; mean age, 17.4 years) were divided into two groups: TAD (21 subjects with 25 edentulous spaces) and FFA (15 subjects with 24 edentulous spaces). The primary outcome measure was the efficiency of protraction [magnitude and time required for protraction (rate) and anchor loss (AL)]. The secondary outcomes involved measuring the type of tooth movement (TOTM), external apical root resorption (EARR), alveolar bone height change (ABHC), alveolar bone width change (ABWC) and appliance failure. Results: The rate of tooth movement was significantly higher for FFAs (0.83 ± 0.35 mm/month) versus TADs (0.49 ± 0.2 mm/month) (P =.005). Total treatment duration was less for FFAs (34.78 ± 8.1 months) versus TADs (47.72 ± 13.94 months) (P =.002). TOTM was similar for both (P =.909). EARR was 1.42 ± 1.38 mm for TAD and 1.25 ± 0.88 mm for FFA (P =.81). ABHC increased in the FFA group (1.01 ± 3.62 mm) and decreased for the TAD group (0.68 ± 1.66 mm). ABWC increased for both TAD (1.81 ± 1.73 mm) and FFA (1.75 ± 1.35 mm). The failure rate was 50% for FFAs and 33% for TADs. Conclusions: Both systems provided translation of lower molars with comparable anchorage control. However, FFAs were more efficient than TADs for lower molar protraction. [ABSTRACT FROM AUTHOR]

Background: Previous studies have reported that periderm (the outer ectodermal layer) in zebrafish partially expands into the mouth and pharyngeal pouches, but does not reach the medial endoderm, where the pharyngeal teeth develop. Instead, periderm-like cells, arising independently from the outer periderm, cover prospective tooth-forming epithelia and are crucial for tooth germ initiation. Here we test the hypothesis that restricted expansion of periderm is a teleost-specific character possibly related to the derived way of early embryonic development. To this end, we performed lineage tracing of the periderm in a non-teleost actinopterygian species possessing pharyngeal teeth, the sterlet sturgeon (Acipenser ruthenus), and a sarcopterygian species lacking pharyngeal teeth, the axolotl (Ambystoma mexicanum). Results: In sturgeon, a stratified ectoderm is firmly established at the end of gastrulation, with minimally a basal ectodermal layer and a surface layer that can be homologized to a periderm. Periderm expands to a limited extent into the mouth and remains restricted to the distal parts of the pouches. It does not reach the medial pharyngeal endoderm, where pharyngeal teeth are located. Thus, periderm in sturgeon covers prospective odontogenic epithelium in the jaw region (oral teeth) but not in the pharyngeal region. In axolotl, like in sturgeon, periderm expansion in the oropharynx is restricted to the distal parts of the opening pouches. Oral teeth in axolotl develop long before mouth opening and possible expansion of the periderm into the mouth cavity. Conclusions: Restricted periderm expansion into the oropharynx appears to be an ancestral feature for osteichthyans, as it is found in sturgeon, zebrafish and axolotl. Periderm behavior does not correlate with presence or absence of oral or pharyngeal teeth, whose induction may depend on 'ectodermalized' endoderm. It is proposed that periderm assists in lumenization of the pouches to create an open gill slit. Comparison of basal and advanced actinopterygians with sarcopterygians (axolotl) shows that different trajectories of embryonic development converge on similar dynamics of the periderm: a restricted expansion into the mouth and prospective gill slits. [ABSTRACT FROM AUTHOR]

Copyright of West China Journal of Stomatology is the property of Sichuan University, West China College of Stomatology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background This study aims to verify Bolton's values for tooth size ratios and to evaluate possible relationships to different occlusal traits using precise digital measurement methods. Materials and methods Including 1000 consecutively selected patients from three study centres a digital, partially automated model analysis was performed utilizing the software OnyxCeph. The measurements comprised tooth width for calculation of anterior (AR) and overall ratio (OR) as a percentage, arch width, length, perimeter, overjet, overbite, space analysis in millimetre and the assessment of the angle classification. Results AR and OR were significantly increased compared to Bolton's ratios of 77.2% (AR) and 91.3% (OR). In the gender comparison, male patients showed larger tooth size ratios, especially in the OR. Patients with Angle Class II/1 and II/2 had smaller tooth size ratios than patients with Angle Class III and I. Thus, patients with Angle Class II/1 had the largest tooth diameters in all maxillary teeth and with Angle Class II/2 the smallest tooth sizes in the mandible. The largest tooth widths in the lower jaw were observed in the Angle Class III patient group. Furthermore, a negative correlation from AR/OR to overjet, overbite, and available space in lower jaw as well as a positive correlation to available space in upper jaw was detected. Conclusions There is a clear correlation between the tooth size ratios and the present dysgnathia as well as other orthodontically relevant occlusal traits. This prior knowledge about our patients is extremely important to create an individualized treatment plan and enable sufficient occlusion. To achieve a functionally good occlusion with correct overjet and overbite, it is essential that the maxillary and mandibular teeth are proportional in size. Any deviation from the ideal patient in terms of tooth size, number, shape, or arch must be considered in the pre-therapeutic treatment plan in combination with the existing dysgnathia in order to be able to achieve a stable anterior and posterior occlusion with appropriate adjustments to the therapy post-therapeutically. [ABSTRACT FROM AUTHOR]

A new genus and species of kitefin sharks (Squaliformes: Dalatiidae), Danodalatias ochevi gen. et sp. nov., is described based on isolated teeth from the lower part of the Berezovaya Strata (Lower Paleocene, Danian Stage) in the vicinity of the farmstead of Rasstrigin (Volgograd Region). The teeth of Centroselachus goordi Mannering et Hiller, 2008 from the Paleocene of New Zealand are reclassified here as Danodalatias goordi (Mannering et Hiller, 2008) comb. nov. The association of these two species with a bipolar distribution into the genus Danodalatias gen. nov. suggests that kitefin sharks (Dalatiidae) were globally distributed back in the Early Cenozoic and inhabited both shallow epicontinental and relatively deep ocean shelf environments during that time. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the accuracy of tooth positions in printed complete dentures with different designs and teeth positioning techniques. Materials and Methods: Five different designs of complete dentures and teeth positioning techniques were evaluated in this in vitro study. In Group I, the denture bases and teeth were designed as a single piece. In groups II and III, the denture bases were designed separately, and the denture teeth were designed as separate teeth. In groups IV and V, the denture bases were designed separately, and the denture teeth were designed as a single piece. Teeth positioning keys were designed for groups III and V. The dentures of all groups were scanned, and the data were imported to the surface matching software to evaluate the accuracy of the teeth positions. Statistical analysis was done using One ‐way ANOVA of Variance. The significance level was set at p ≤ 0.05. Results: The results showed that the highest deviations of the positions of the canines (0.0781 ± 0.0154 mm) and the first molars (0.0611 ± 0.0055 mm) were found in Group II. On the other hand, Group I showed the least deviations of the positions of the canines (0.0287 ± 0.0054 mm) and molars (0.0354 ± 0.005 mm). Conclusions: The most accurate tooth positions are obtained in monolithic printed complete dentures. Fewer deviations in tooth positions occur when denture teeth are designed as a single piece. [ABSTRACT FROM AUTHOR]

An esthetic peri‐implant soft tissue contour is a critical element of the success of implant restorations in the esthetic zone. Once the optimal transmucosal soft tissue profile is formed, it needs to be accurately replicated on the master cast. This clinical technique involves the utilization of a silicone putty positioning index placed in the patient's mouth to accurately duplicate the external contour of teeth and soft tissue. By combining this positioning index with the implant‐supported interim crown, the 3D‐printed initial cast, which was used to fabricate the interim crown, can be conveniently and efficiently transformed into a definitive master cast. [ABSTRACT FROM AUTHOR]

Background/Objectives: This study compared the accuracy and efficiency of different surgical-guide (SG)-assisted and freehand drilling techniques for removing fiber posts from maxillary anterior teeth performed by differently experienced operators. Methods: A fiber post was bonded to the root canal of 54 extracted maxillary anterior teeth. After mounting the teeth in the jaw models, SGs were designed by integrating cone-beam computed tomography (CBCT) and intraoral scanner data. Each SG included a custom sleeve. An experienced or inexperienced operator drilled the post using three different techniques: (i) SG-assisted incremental drilling at 2–3 mm (SG1), (ii) SG-assisted one-time drilling to a predetermined depth (SG2), and (iii) freehand incremental drilling without SG (FH; n = 9 in each group). Deviations in coronal, sagittal, and horizontal planes and the angle of deviation were measured. Results: The SG1 and SG2 groups showed significantly smaller sagittal and horizontal deviations than the FH group, regardless of the operator's experience. The SG2 group had a significantly shorter working time than the SG1 and FH groups. In the FH group, the experienced operator required a significantly shorter working time than the inexperienced operator. Conclusions: SG-assisted drilling techniques enhanced the accuracy and efficiency of removing fiber posts from the anterior teeth, irrespective of the operator's experience. [ABSTRACT FROM AUTHOR]

Background/Objectives: This study aimed to evaluate the effect of ProDesign Logic files 45.01 and 50.01 on apical foramen wear and shape transformation after foraminal enlargement at tooth length (TL) and 1 mm beyond. Methods: Sixty freshly extracted single-rooted lower human premolars teeth were distributed randomly into five groups (n = 12): Group 1 (40.05 WL) (control): No foraminal enlargement, Group 2 (45.01 TL): Specimens underwent foraminal enlargement with 45.01 Prodesign Logic file at TL; Group 3 (45.01 TL + 1): Specimens underwent foraminal enlargement with 45.01 Prodesign Logic file at 1 mm beyond TL; Group 4 (50.01 TL): Specimens underwent foraminal enlargement with 50.01 Prodesign Logic file at TL; Group 5 (50.01 TL + 1): Specimens underwent foraminal enlargement with 50.01 Prodesign Logic file at 1 mm beyond TL. Scanning electron microscopy was used to evaluate apical foramen variations and shape alterations. Data were analyzed by Student's t-test, Kruskal–Wallis, and Mann–Whitney test. Results: Significant differences (p < 0.01) were observed among all tested groups compared to the control group in terms of the average worn area of the apical foramen. Foraminal enlargement led to significant shape transformation, resulting in round-shaped foramina. Conclusion: ProDesign Logic 45.01 and 50.01 files at TL causes notable wear and round-shaped foramina. [ABSTRACT FROM AUTHOR]

Aim: The aim of this study was to compare the fitting accuracy of custom-made metal posts and cores fabricated by half-digital and milling technique to that of conventional cast posts fabricated by direct technique. Methods: Sixteen extracted single-rooted teeth were endodontically treated followed by post space preparation. A direct resin post and core pattern was made for each tooth and used for the fabrication of two posts (n = 16). Each post resin pattern was digitized with a laboratory scanner and used for the fabrication of a milled cobalt–chrome (Co–Cr) alloy post, while the direct resin pattern, after scanning, was cast in a Co–Cr alloy to produce a cast post. Each post was seated on its respective tooth and evaluated using microcomputed tomography. The following variables were evaluated: total space volume between the post and root canal, the volume and distance of the apical gap between each post and the remaining apical root canal filling, as well as the distance and surface area of the space between the post and lateral root canal wall at four determined points along the length of each post. Results: The results revealed that half-digital and milled posts had a statistically significantly higher total space volume (p < 0.05), apical gap volume (p < 0.02) and distance (p < 0.02), as well as a higher surface area of space between the post and root canal wall at the cervical area as compared to the cast post (p < 0.05). Conclusions: This study demonstrated that the fitting accuracy of cast posts was more accurate than posts fabricated with half-digital and milling technique. [ABSTRACT FROM AUTHOR]

Computer-assisted preparation of porcelain laminate veneers (PLVs) using stereolithographic templates has been developed to enhance the accuracy of tooth preparation. However, the digital workflows involved in guided PLV preparation remain inconsistently defined across various practices. Therefore, this scoping review aimed to examine publications on computer-assisted PLV preparation to identify the key stage of digital workflows involved in designing and fabricating stereolithographic templates, as well as to highlight the limitations of various template designs. This scoping review aimed to identify publications on digital workflows for designing and fabricating stereolithographic templates in computer-assisted porcelain laminate veneer preparation. A systematic search on MEDLINE/PubMed, Web of Science and Scopus identified English-language articles published from 2014 to March 2024. Eligible articles focused on digitally designed and fabricated tooth reduction templates for porcelain laminate veneers, excluding conventional tooth preparation procedures for tooth reduction assessment. Seven clinical reports were included, demonstrating various 3D data acquisition techniques for virtual patient generation. All articles described virtual diagnostic wax-ups on digital casts, with two using a virtual articulator. Only five articles documented chair-side mock-ups with resin trial restorations to evaluate planned dental esthetics. Additionally, virtual tooth preparation prior to templates design was included in only four articles. The templates were designed using different software and ranged from simple designs with access windows to complex stacked templates with rotary instrument sleeved windows. Each template design had limitations affecting tooth reduction accuracy. All articles reported printing templates in clear acrylic resin using different technologies. In conclusion, the review highlights a lack of standardization in the digital workflow for designing stereolithographic templates for PLVs. Establishing a sound protocol for designing the tooth reduction templates is essential to ensure the accuracy and consistency of veneer preparation. [ABSTRACT FROM AUTHOR]

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Quintessenz der Zahntechnik is the property of Quintessenz Verlags GmbH and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Quintessenz der Zahntechnik is the property of Quintessenz Verlags GmbH and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

ABSTRACT Background Objective Methods Results Conclusions Tooth wear is a multifactorial process resulting in the loss of dental hard tissues. For its assessment, the tooth wear evaluation system (TWES) 2.0 has been published. Previous studies on the TWES involved well‐trained practitioners, rather than nonexperts.The first aim of this study was to investigate the reliability of the assessment of tooth wear severity on dental hard tissues, using the TWES 2.0, by nonexperts. The second aim was to investigate the reliability of assessment of wear severity on dental restorations, using a third scale.Forty‐seven dental students evaluated at least 9 of 14 possible patient cases on dental casts and intraoral photographs. Cohen's kappa (agreement with sample solution) and Fleiss' kappa (Inter‐rater reliability) were calculated.The agreements of the operators' ratings compared to the sample‐solution resulted in Cohen's kappa between 0.02 and 0.9. The agreements were 0.34 for occlusal; 0.43 for vestibular; 0.57 for oral surfaces.Inter‐rater reliability (Fleiss' kappa) was 0.35 for occlusal, 0.17 for vestibular and 0.24 for oral assessment. The inter‐rater reliability of the ratings on tooth surfaces with restorations was lower with 0.21 (occlusal), 0.14 (vestibular) and 0.39 (oral). The agreement on different restorations differed tremendously.The ability to correctly assess the cases varied considerably between individual examiners. Within the limits of this study, assessment of restorations was slightly more challenging compared to natural teeth, particularly in occlusal regions or when the restorative material is gold. Subsequent studies should address whether enhanced training and improved definition of tooth wear grades result in higher reliability scores. [ABSTRACT FROM AUTHOR]

Dental avulsion is a traumatic dental injury with complete displacement of the tooth outside the bony socket. Both primary and permanent teeth are predisposed to such traumatic incidents. The most effective treatment in such cases is tooth replantation. Additionally, a short‐term flexible splint is needed to stabilize the avulsed/replanted tooth. This case report describes orthodontic braces as a standardized flexible splint option for the treatment of tooth avulsion. Herein, the case of a 9‐year‐old female patient who presented to a private dental clinic with an avulsed upper left central incisor, 1 h after the accident has occurred. Once the tooth was replanted with all the necessary precautions, orthodontic braces and wire were utilized to stabilize the tooth. Most dental splints are custom‐made, requiring thorough professional knowledge and expertise for their fabrication and placement. The protocol described in this report is aimed at easing tooth stabilization using materials within the scope of a basic dental setup consultation room. [ABSTRACT FROM AUTHOR]

Background: Limited treatment options exist for damaged nerves and despite impressive advances in tissue engineering, scientists and clinicians have yet to fully replicate nerve development and recruitment. Innervation is a critical feature for normal organ function. While most organs are innervated prior to birth, a rare example of postnatal nerve recruitment occurs in the natural development of secondary teeth during adolescence. Many animals undergo postnatal shedding of deciduous teeth with development and eruption of secondary teeth, a process requiring recruitment of nerve and vasculature to each tooth pulp for viability. Here, the investigators created a novel model for the study of postnatal innervation by exploiting the natural phenomenon of tooth-driven nerve recruitment. Methods: The investigators theorized that developing teeth possess a special capacity to induce innervation which could be harnessed in a clinical setting for nerve regeneration, and hyptothesized that a transplant model could be created to capture this phenomenon. In this descriptive study, a rat model of autologous tooth transplantation and de novo nerve recruitment was developed by surgically transferring whole developing molars to the autologous tibia. Results: Downstream histological analysis performed 6 to 14 weeks after surgery demonstrated integration of molar into tibia in 81% of postoperative rats, with progressive pulpal expression of nerve marker ß-tubulin III suggestive of neuronal recruitment. Conclusions: These findings provide a novel model for the study of organ transplantation and support the theory that developing dental tissues may retain nerve-inductive properties postnatally. [ABSTRACT FROM AUTHOR]

Objective The aim of this study was to explore the impact of implant robots on the oral function and aesthetic effects of immediate implant patients in the aesthetic area of anterior teeth. Methods A total of 68 patients with single anterior tooth defects admitted to the hospital from January 2021 to January 2023 were enrolled and divided into a study group of 34 cases and a control group of 34 cases randomly. In the study group, anterior tooth immediate implantation was performed with the assistance of an oral implantation robot, while the control group underwent conventional immediate anterior tooth implantation. The implantation accuracy, postoperative bite function, aesthetic restoration, and occurrence of complications were compared between the two groups, and complications were all recorded. Results After final restoration, all patients were followed up for 2 years, and the implant success rate was 100% (68/68 cases). The study group exhibited significantly lower postoperative apical point error and implant angle error compared to the control group (P < 0.05). There was no significant difference in speech clarity, bite pressure, and pain intensity between the two groups (P > 0.05). The ratio of implant bite pressure to that of the contralateral homonymous tooth was higher in the study group than in the control group (P < 0.05). The postoperative pink esthetic score (PES) and white esthetic score (WES) in the study group were higher than those in the control group (P < 0.05). There was no statistically significant difference in the incidence of complications between the two groups (P > 0.05). Patient satisfaction in the study group was higher than that in the control group (P < 0.05). Conclusion The use of oral implantation robots for immediate implantation in the aesthetic zone of anterior teeth resulted in higher intraoperative positioning accuracy and yielded favorable outcomes in postoperative restoration of bite function and aesthetics. [ABSTRACT FROM AUTHOR]

Background: Gaze behavior can serve as an objective tool in undergraduate pre-clinical dental education, helping to identify key areas of interest and common pitfalls in the routine evaluation of tooth preparations. Therefore, this study aimed to investigate the gaze behavior of undergraduate dental students and dental educators while evaluating a single crown tooth preparation. Methods: Thirty-five participants volunteered to participate in the study and were divided into a novice group (dental students, n = 18) and an expert group (dental educators, n = 17). Each participant wore a binocular eye-tracking device, and the total duration of fixation was evaluated as a metric to study the gaze behavior. Sixty photographs of twenty different tooth preparations in three different views (buccal, lingual, and occlusal) were prepared and displayed during the experimental session. The participants were asked to rate the tooth preparations on a 100 mm visual analog rating scale and were also asked to determine whether each tooth preparation was ready to make an impression. Each view was divided into different areas of interest. Statistical analysis was performed with a three-way analysis of the variance model with repeated measures. Results: Based on the participants' mean rates, the "best" and the "worst" tooth preparations were selected for analysis. The results showed a significantly longer time to decision in the novices compared to the experts (P = 0.003) and a significantly longer time to decision for both the groups in the best tooth preparation compared to the worst tooth preparation (P = 0.002). Statistical analysis also showed a significantly longer total duration of fixations in the margin compared to all other conditions for both the buccal (P < 0.012) and lingual (P < 0.001) views. Conclusions: The current study showed distinct differences in gaze behavior between the novices and the experts during the evaluation of single crown tooth preparation. Understanding differences in gaze behavior between undergraduate dental students and dental educators could help improve tooth preparation skills and provide constructive customized feedback. [ABSTRACT FROM AUTHOR]

The present study focuses on the elimination of delamination during the drilling of a linen-based biocomposite material in epoxy resin used for the manufacture of sports kayaks, depending on the tool material, cutting conditions, and the use of additional wooden support plates. In the present study, HSS (high-speed steel) and Carbide cutting tools without coatings, with the same geometry and two types of cutting conditions (n = 1500 rpm, fn = 0.05 and 0.1 mm/rev) were used. A Sololite-type wooden backing plate was used to aid in reducing delamination. The results show that the additional support plates significantly reduced delamination by up to 80% both at the material inlet and especially at the drill hole outlet. In this study, the use of a lower feed rate (fn = 0.05 mm/rev) per tooth was shown to have a significant effect on reducing the delamination of biocomposite materials with flax fibers, which are generally known to be difficult to machine. The Carbide cutting tool shows significantly better results both in terms of its wear and in terms of delamination of the biocomposite material. The highest delamination was obtained without the use of a backing board at the tool exit after 50 drilled holes of 3509 µm. With the use of a backing board, this delamination decreased to 693 µm after 50 drilled holes. [ABSTRACT FROM AUTHOR]

The unequal pitch end milling cutter can change the feed per tooth and the cut-in and cut-out period of each cutter tooth by changing the distribution of the pitch of the end milling cutter so that the energy in the milling frequency domain is dispersed to achieve the purpose of reducing the milling vibration. Because the amplitude of vibration in the milling process is closely related to the milling force, this paper establishes the instantaneous static milling thickness model based on the real trajectory of the milling edge according to the milling process of the end milling cutter with unequal pitch and establishes the instantaneous dynamic milling thickness model based on the regeneration effect, on which the instantaneous milling force model is established. At the same time, the relationship model of milling force coefficient is established according to the average milling force method. From the relationship model of milling force coefficient, the linear relationship between average milling force and average feed per tooth is obtained. Then, the finite element simulation method is used to simulate the actual milling process of milling typical material Al7075-T6 with unequal pitch end mill, and the milling force coefficient is fitted by the simulation results. Finally, the accuracy of the milling force model and the finite element model has been validated through experiments, and the feasibility of calibrating the milling force coefficients through finite element simulation method has been demonstrated. The milling force model of unequal pitch end mill and the method of calibrating the milling force coefficient by finite element simulation proposed in this paper will provide a theoretical basis for the study of unequal pitch end mill in vibration reduction. [ABSTRACT FROM AUTHOR]

Background/Objectives: Many older adults living in long-term care (LTC) environments have varying numbers of retained natural teeth. The objective of this study was to assess the disease findings based on tooth type and estimate the role of tooth types in occlusion. Methods: We conducted clinical oral examinations of 276 LTC residents. The disease findings were analyzed for each tooth type and to determine their associations with dementia. Results: In total, 67.8% of the participants had molar teeth. Premolars/canines were often present as residual roots and had caries. Deepened periodontal pockets and higher plaque index (PI) values for molars had odds ratios of 2.5 (95% confidence interval [CI] of 1.59–3.91) and 1.61 (95% CI of 1.29–2.02), respectively. Participants with dementia were more likely to have incisors and premolars/canines in the form of root remnants and higher PI scores for all tooth types (p ≤ 0.01), as well as more deepened periodontal pockets in all teeth (p = 0.029), than those without dementia. The median number of remaining molars per participant was 3 out of a maximum of 12 (95% CI 3.4–4.0); thus, they often lacked occlusal contact. Conclusions: The LTC residents' molars were more prone to periodontal problems, whereas their premolars/canines often had caries or were present in the form of root remnants, especially in the participants with dementia. People's teeth should be treated in an easy-to-maintain way before they move into LTC to enable daily oral hygiene measures and maintain oral health. [ABSTRACT FROM AUTHOR]

Infrared thermal imaging (IRT) remotely and contactless maps the temperature on the examined surface, recording the distribution of infrared radiation emitted by each body whose temperature is higher than absolute zero. The aim of the study was to evaluate the usefulness of thermography in the assessment of asymptomatic infection foci in patients with high systemic infection. The 150 cases diagnosed based on roentgenograms, divided into 6 groups of diagnosed odontogenic lesions, along with a control group. Thermal imaging was performed with a FLIR Systems T1020 thermal camera. Thermal image analysis was performed using ThermaCAM Researcher Pro 2.10, MS Office Excel 2022 and Statistica 10. The periapical areas of selected dead teeth were selected as areas of interest. The Mann Whitney’s U test showed statistically significant (p < 0.001) differences in average temperature between each patient’s and healthy group. Depper’s analysis showed statistical significance also between the ZM and BZ groups (p = 0.004). Moreover, obtained results may also suggest that thermal imaging can be useful in identify odontogenic infection foci. The thermal asymmetry of periapical tissues of teeth differentiates dead from living teeth, as well as individual pathologies related to the process of gangrenous pulp decay. Thermographic mapping is a promising diagnostic technique that can detect asymptomatic inflammations that carry the risk of infection of the entire body. [ABSTRACT FROM AUTHOR]

ABSTRACT Aim Material and Methods Results Conclusions To assess the impact of active (APT) and supportive periodontal therapy (SPT) on the change in probing depth (PD) and annual tooth loss in partially and fully compliant and drop‐out patients.Data of 280 periodontally treated partially and fully compliant (regular supportive visits, SPT duration 5.5 ± 4.5 years) and 55 drop‐out patients (SPT and drop‐out duration 8.3 ± 3.8 years, only drop‐out duration 5.3 ± 3.7 years) were recorded. PD data and the number of teeth present at the start of APT (T1) and at the start of SPT (T2) were taken from the patient files and evaluated at the time of the final examination (T3).Annual tooth loss during SPT was significantly higher (p < 0.001) in drop‐out patients than in partially and fully compliant patients (0.31 ± 0.50 vs. 0.19 ± 0.55, respectively). In partially and fully compliant and drop‐out patients, the mean PD (all available site data) decreased significantly between T1 (3.61 ± 0.82 vs. 3.70 ± 0.73 mm) and T2 (2.68 ± 0.40 vs. 2.76 ± 0.42 mm), while the values increased again slightly up to T3 (2.74 ± 0.41 vs. 2.99 ± 0.75 mm).In partially and fully compliant patients, SPT had a positive impact on PD stability and medium‐term tooth preservation. In contrary to expectations, drop‐out patients, PD did not return to baseline values, although PD stability was not achieved. [ABSTRACT FROM AUTHOR]

Hyperdontia refers to an excess number of teeth past the expected number of teeth for an individual located in the mandible or maxilla. These extra teeth are often referred to as "supernumerary." This condition is a relatively uncommon, infrequent phenomenon scarcely documented in Ursidae globally, with only a handful of examples documented in literature. In 2008, an indigenous hunter harvested a grizzly bear (Ursus arctos) in Smithers, British Columbia, Canada. The bear exhibited 7 maxillary incisors, with a supernumerary tooth present. This observation serves as the first-ever record of the supernumerary dentition of the incisors in brown bears. [ABSTRACT FROM AUTHOR]

Identifying evidence of human modification of extinct animal remains, such as Pleistocene megafauna, is challenging due to the similarity of anthropogenic and non-anthropogenic taphonomic features observed under optical microscopy. Here, we re-investigate a Late Pleistocene ground sloth tooth from northeast Brazil, previously suggested as human-modified based only on optical observation. To characterize the macro- and micro-morphological characteristics of the marks preserved in this tooth and evaluate potential human modification, we used stereomicroscope and scanning electron microscopy (SEM) supplemented by energy dispersive spectroscopy (EDS), UV photoluminescence (UV/PL), synchrotron-based X-ray fluorescence (SR-XRF), and synchrotron micro-computed tomography (SR-µCT). These methods allowed us to discriminate non-anthropogenic taphonomic features (root and sedimentary damage), anthropogenic marks, and histological features. The latter shows the infiltration of exogenous elements into the dentine from the sediments. Our evidence demonstrates the sequence of anthropogenic and non-anthropogenic taphonomic modification of this tooth and supports its initial intentional modification by humans. We highlight the benefits of emerging imaging and spectral imaging techniques to investigate and diagnose human modification in fossil and archaeological records and propose that human modification of tooth tissues should be further considered when studying possibly anthropogenically altered fossil remains. [ABSTRACT FROM AUTHOR]

Background: The analgesia after lower third molar alveolectomy is based on the use of non-steroidal anti-inflammatory drugs (NSAIDs) that have significant risks, and are contraindicated in the third trimester of pregnancy. Aiming to reduce NSAIDs use after this surgery, we quantified analgesic effects of ultrasound (US)-guided extraoral mandibular nerve block. Methods: Thirty-six patients were equally allocated to the experimental or control group, based on their willingness to receive experimental US-guided extraoral mandibular nerve block for postoperative analgesia. The experimental block applied prior to lower third molar alveolectomy, was followed by standard intraoral inferior alveolar nerve block. In the control group, patients received only intraoral block of inferior alveolar nerve. All patients reported pain level (visual analogue scale, VAS) right after the application of blocks. The next day, patients reported duration of pain-free time and the use of analgesic. Results: The US-guided extraoral mandibular nerve block prolonged the pain-free time to 8 h (vs. 4 in control group, P < 0.001) and reduced NSAIDs use (12 patients needed analgesic in experimental vs. 17 patients in control group, P = 0.038). The application of experimental block was less painful (VAS = 2) than the application of intraoral inferior alveolar nerve block (VAS = 4, P = 0.011). In 8/18 patients in the experimental group US-guided extraoral mandibular nerve block solely achieved adequate surgical anesthesia. Conclusion: US-guided extraoral mandibular nerve block prolonged pain-free period and reduced the use of NSAIDs after lower third molar alveolectomy, thus proving to be successful analgesia method for this dental surgery. Clinical trial registration: https://classic.clinicaltrials.gov/ct2/show/NCT06009302, identification number: NCT06009302, date of registration: 18/08/2023. [ABSTRACT FROM AUTHOR]

Background: This study aims to evaluate the performance of a deep learning system for the evaluation of tooth development stages on images obtained from panoramic radiographs from child patients. Methods: The study collected a total of 1500 images obtained from panoramic radiographs from child patients between the ages of 5 and 14 years. YOLOv5, a convolutional neural network (CNN)-based object detection model, was used to automatically detect the calcification states of teeth. Images obtained from panoramic radiographs from child patients were trained and tested in the YOLOv5 algorithm. True-positive (TP), false-positive (FP), and false-negative (FN) ratios were calculated. A confusion matrix was used to evaluate the performance of the model. Results: Among the 146 test group images with 1022 labels, there were 828 TPs, 308 FPs, and 1 FN. The sensitivity, precision, and F1-score values of the detection model of the tooth stage development model were 0.99, 0.72, and 0.84, respectively. Conclusions: In conclusion, utilizing a deep learning-based approach for the detection of dental development on pediatric panoramic radiographs may facilitate a precise evaluation of the chronological correlation between tooth development stages and age. This can help clinicians make treatment decisions and aid dentists in finding more accurate treatment options. [ABSTRACT FROM AUTHOR]

The present study investigates the correlation between mechanical properties and laser-induced breakdown spectroscopy (LIBS) for different tooth samples. A set of Fourteen samples collected from the Al-Kut Specialized Dental Centre in Wasit Governorate was analysed. Tooth samples were divided into groups depending on age and gender (men, women). The optical emission of the ionic-to- atomic intensity ratio of the Ca spectral line has been correlated with Leeb hardness test (LHT) values, compressive strength, and Young's modulus measured by standard tools. The ratio ionic line to atomic line CaII / CaI between the ionic calcium line at 396.84 nm and the atomic line at 558.87 nm for teeth is obtained using LIBS technique employing Nd: YAG laser with a wavelength of 1064 nm, an energy of 200 Mj, and a pulse duration of 10 ns. A linear relationship was observed between compressive strength, Young's modulus and hardness, and the concentrations of the elements (Ca). The small relative errors for hardness, compressive strength, and Young's modulus ranged from (1.44-5.57) %, (1.94-6.07) %, and (0.243-4.01) %, respectively. These findings validate applying LIBS to check out some important mechanical properties. [ABSTRACT FROM AUTHOR]

As the teeth are more durable than other parts of the skeleton, they provide valuable data for age estimation. Age estimation from adult teeth is mainly based on secondary dentin production. The present study aimed to devise a regression formula for age estimation specific to the Anatolian population using the Kvaal method on CBCT reconstructed panoramic images. In total, 201 individuals aged between 20 and 69 were divided into two groups: data from the study group (n = 101) were used to create the regression formulae, and data from the control group (n = 100) were used to test the formulae. Pearson's correlation coefficients and linear regression analyses were performed. Maxillary teeth provided more accurate age estimates than mandibular teeth. The regression formulae derived in this study are found to be statistically applicable and reasonably accurate. However, these results should be interpreted with caution. [ABSTRACT FROM AUTHOR]

Bow-collapse is a type of geometric defect in the gear cold roll-beating process. In order to effectively control bow-collapse and improve material utilization, this paper calculates the cross-section radius of the blank according to the volume invariance principle of metal plastic deformation, and then performs FE simulation of the cold roll-beating process by using the cyclic beating of adjacent tooth spaces and intermittent blank feeding method. The flow state of metal particles is investigated, revealing that the movement of metal particles along the axial direction of the blank is the main reason for the formation of bow-collapse. This paper proposes a method to correct the cross-section radius of the blank and thus control for bow-collapse, where the loss coefficient K characterizes the state of metal particle loss in an infinitesimal thickness region on the cross-section. The analytical equation for calculating the corrected value of the cross-section radius is derived, and the corrected value is calculated. Conducted on the modified blank, cold roll-beating FE simulation results show that bow-collapse is effectively controlled, and the loss coefficient K correctly reflects the loss state of metal particles on the cross-section. The simulation results also show that after cold rollbeating, the gear teeth with standard face width and tooth depth can be obtained after two turning end faces and turning tip circle processes. The bow-collapse control method proposed in this paper effectively improves material utilization. [ABSTRACT FROM AUTHOR]

Sauropod teeth are commonly categorized taxonomically by two well‐established measurement indices: slenderness index (SI; apicobasal height/mesiodistal width), which quantifies breadth, and compression index (CI; labiolingual width/mesiodistal width), which quantifies cross‐sectional circularity. Although both indices are used to infer high‐level taxonomic affinities, little is known about the linear relationships between the constituent measurements or how the indices vary intra‐cranially and at lower taxonomic levels. Here, we evaluate these relationships using a novel dataset of sauropod teeth (N = 898) spanning all major sauropod groups. Results for both indices indicate significant differential scaling within Sauropodomorpha, both in slope and elevation. Broad‐crowned sauropods mostly display positive allometry in SI compared to isometry in narrow‐crowned sauropods. However, this distinction is less clear with CI as most sauropods display isometry, whilst non‐sauropod sauropodomorphs (e.g. Plateosauridae) display positive allometry. An anova reveals SI varies significantly with genus and tooth position. Specifically, jaw type (maxilla and dentary) is significant within Plateosauridae, whilst tooth position is significant within titanosaurs. Overall, variation within CI is restricted to genus. Our findings reveal that whilst indices have taxonomic utility, there are caveats. The measurements used to calculate the indices exhibit significant allometry, indicating that index values are size‐dependent. Furthermore, the indices may not accurately reflect size heterodont conditions present among early‐branching sauropodomorphs. Our study highlights the importance of quantifying taxonomic relationships of measurement data, which can be used to inform hypotheses regarding the physiological and palaeoecological drivers influencing tooth shape evolution. [ABSTRACT FROM AUTHOR]