Tooth Shape Research Articles

Prevalence of Dental Anomalies in Pediatric Patients visiting Tertiary Care Hospital: A Panoramic Radiograph based study

Introduction: Dental anomalies are deviations from the normal development, structure, or appearance of teeth. These anomalies can affect the number, size, shape, position, and structure of teeth. Objective: This study aimed to assess the prevalence of dental anomalies in the pediatric patients visiting Kathmandu University School of Medical Sciences (KUSMS), Dhulikhel Hospital, Nepal. Methods: A descriptive cross-sectional study was conducted at KUSMS, Dhulikhel Hospital. The panoramic radiographs of the pediatric patients between 6 and 14 years of age in the archive of the hospital were assessed for the presence of dental anomalies. Results: Of the total 451 panoramic radiographs meeting the inclusion criteria, 55.9% were male and 44.1% were female. The overall prevalence of dental anomaly was 26.8 % with rotation as the most common anomaly (19.3%) followed by missing (6.7%), supernumerary teeth (4.4%), dilaceration 2.4 %, gemination (1.8%), dens-in-dente (1.1%) and peg shaped (0.9%). Conclusions: The most common dental anomaly among the pediatric patients was rotation followed by missing and supernumerary tooth.

LMVSegRNN and Poseidon3D: Addressing Challenging Teeth Segmentation Cases in 3D Dental Surface Orthodontic Scans.

The segmentation of teeth in 3D dental scans is difficult due to variations in teeth shapes, misalignments, occlusions, or the present dental appliances. Existing methods consistently adhere to geometric representations, omitting the perceptual aspects of the inputs. In addition, current works often lack evaluation on anatomically complex cases due to the unavailability of such datasets. We present a projection-based approach towards accurate teeth segmentation that operates in a detect-and-segment manner locally on each tooth in a multi-view fashion. Information is spatially correlated via recurrent units. We show that a projection-based framework can precisely segment teeth in cases with anatomical anomalies with negligible information loss. It outperforms point-based, edge-based, and Graph Cut-based geometric approaches, achieving an average weighted IoU score of 0.97122±0.038 and a Hausdorff distance at 95 percentile of 0.49012±0.571 mm. We also release Poseidon's Teeth 3D (Poseidon3D), a novel dataset of real orthodontic cases with various dental anomalies like teeth crowding and missing teeth.

Development of an anchor system for thick CFRP plates: Experimental and numerical investigation

Carbon fiber reinforced polymer (CFRP) has been widely used in construction, rehabilitation and maintenance of civil infrastructures. Anchor system is one of the most crucial part ensuring load transfer between CFRP and the structures. However, for CFRP plate anchors, there is a contradiction between the anchor capacity and the anchor size. In this paper, a novel cylinder shaped anchor for thick CFRP plates was developed based on a detailed experimental and numerical study. The proposed anchor weighs only 6 kg and it can develop 98 % strength of the 3 mm thickness CFRP plates. The experimental and numerical results revealed that the anchor efficiency of the proposed cylinder shaped anchor system is significantly affected by wedge shape, anchor material, tooth shape, pretightening force and magnitude of interference. The proposed anchor system can significantly promote application of thick CFRP plates.

Knowledge, Attitude, And Oral Hygiene Practices Among Law Students In Chengalpatu District: A Cross‑Sectional Study

Introduction: poor oral health can have a profound effect on the quality of life. The experience of pain, endurance of dental abscesses, problems with eating and chewing, embarrassment about the shape of teeth or about missing, discoloured or damaged teeth can adversely affect people's daily lives and wellbeing. The purpose of this study was to evaluate the oral hygiene and dental health knowledge of government law college, chengalpatu district, law students. Materials and methods: thirty questions about fundamental knowledge, mindset, and practice were given to one hundred and fifty law students at the government law college in chengalpatu district, tamilandu india. Microsoft excel was used to tabulate the data, and the statistical package for the social sciences programme was used for statistical analysis. Results: of the participants in this study, only 39.4% were aware that regular dental check-ups were necessary. 8.5% of participants made two annual visits to the dental clinic andof the individuals, 57% had never been to a dental facility. Dental health education is important, according to 65.5% of participants, and it may be important, according to 21.8%. The results indicated a statistically significant association between the participant's year of law degree and the responses, as determined by inferential statistics using the pearson chi-square test. Conclusion: the study's findings indicate that law students' understanding of oral health care and proper oral hygiene is adequate. But the learned knowledge needs to be applied in day-to-day activities. This can be accomplished by altering their perspective on maintaining good dental hygiene

Experimental study on the rock breaking effect of different tooth shapes of inserted teeth in a hobbing-cone hybrid PDC bit under complex stress environment

The hobbing-cone hybrid PDC bit has emerged with the increasing exploitation of deep oil and gas resources. As an important component of new bits, studying the mechanism of toothed fracturing of deep rocks is crucial for improving rock-breaking efficiency. In this paper, the spherical teeth and conical teeth were used to intrude sandstone under different confining pressures, and the brittleness index (BIm), specific energy (SE), and average fragment size (dm) were used to analyze the rock-breaking effect. The 3D contour scanner quantitatively analyzed the crushing pit area. Finally, the in-situ CT scanning and discrete element numerical simulation were used to summarize the crack propagation law. The results show that with the increase of confining pressure, the BIm of inserted teeth increases continuously, and the growth rate of conical teeth increases, while that of spherical teeth decreases. The SE and dm exhibit a symmetrical distribution with a confining pressure of 10MPa as the axis of symmetry. When the difference in principal stress is 5MPa, the SE is the lowest point, the rock-breaking efficiency is the highest, and the corresponding dm is at the highest point, but the curve trend is the opposite. When the stress difference is 5MPa, it is conducive to propagating surface cracks, thus forming a larger crushing area and the highest rock-breaking efficiency. Based on CT results, the dense particle core is formed near the inserted teeth, and that of the spherical teeth is located below. In contrast, that of the conical teeth is located on the side, which is also the reason for the difference in crack propagation between different tooth shapes.

Three new species of Isodon (Nepetoideae, Lamiaceae) from China.

Three new species of Isodon (Lamiaceae) from China are described and illustrated, based on both morphological evidence and our recent phylogenomic studies of the genus. Isodonattenuatus, a herbaceous new species known only from the Fanjing Mountain, is shown to be sister to I.villosus, but they can be easily distinguished by leaf and inflorescence indumentum, calyx teeth shape and corolla tube morphology. Isodongongshanensis, a herbaceous new species collected from the Hengduan Mountains in southwest China, represents a distinct lineage within the genus. Isodonsukungii, a shrubby new species also endemic to the Hengduan Mountains, was previously misidentified as I.tenuifolius, but they are phylogenetically distantly related and differ in lamina size and margin, inflorescence type and corolla length and shape.

Direct Composite Restorations on Permanent Teeth in the Anterior and Posterior Region - An Evidence-Based Clinical Practice Guideline - Part 1: Indications for Composite Restorations.

This German S3 clinical practice guideline offers evidence-based recommendations for the use of composite materials in direct restorations of permanent teeth. Outcomes considered were the survival rates and restoration quality and process quality of the manufacturing process. Part 1 of this two-part presentation deals with the indication classes. A systematic literature search was conducted by two methodologists using MEDLINE and the Cochrane Library via the OVID platform, including studies up to December 2021. Six PICO questions were developed to guide the search. Recommendations were formulated by a panel of dental professionals from 20 national societies and organizations based on the collected evidence. Composite materials are a viable option for the direct restoration of cavity Classes I-V and may also be used for restorations with cusp replacement, and tooth shape corrections. In the posterior region, direct composite restorations should be preferred over indirect composite inlays. For Class V restorations, composite materials can be used if adequate contamination control and adhesive technique are ensured. The guideline is the first to provide comprehensive evidence on the use of direct composite materials. However, further long-term clinical studies with comparators such as (modified) glass-ionomer cements are necessary. Regular updates will detail the future scope and limitations of direct composite restorations.

Molar enamel–dentine junction shape of Pliobates cataloniae and other Iberian pliopithecoids

The phylogenetic relationships of the small-bodied catarrhine Pliobates cataloniae (∼11.6 Ma, NE Iberian Peninsula) have been controversial since its original description. However, the recent report of additional dentognathic remains has supported its crouzeliid pliopithecoid status. Based on the available hypodigm, the molar enamel–dentine junction (EDJ) shape of P. cataloniae is compared with that of other pliopithecoids from the same basin as well as both extinct and extant hominoids to further evaluate its pliopithecoid affinities. We also quantitatively compare the EDJ shape among these taxa by means of landmark-based three-dimensional geometric morphometrics using principal component analysis (PCA), canonical variate analysis, and between-group PCA. Permutation tests are performed to test whether Pliobates variation exceeds that of extant hominoid genera. Results indicate that Pliobates is similar in molar EDJ shape to other pliopithecoids, particularly crouzeliids. The variation displayed by Pliobates upper molars is less marked at the EDJ level than at the outer enamel surface, probably owing to differential enamel wear and intraspecific differences in enamel thickness. Multivariate analyses of EDJ shape show that all pliopithecoids (including Pliobates) cluster together in the PCAs, canonical variate analyses, and between-group PCAs and occupy a different portion of the morphospaces from extinct and extant hominoids. Posterior and typicality probabilities strongly support the classification of Pliobates as a pliopithecoid, wheras permutation tests fail to reject the single-genus hypothesis for the P. cataloniae hypodigm. We conclude that P. cataloniae is a crouzeliid pliopithecoid, as recently supported by cladistic analyses of craniodental characters, and that previous cladistic results that supported a stem hominoid status are attributable to postcranial convergences with crown hominoids. Our results further highlight the potential of three-dimensional geometric morphometrics analyses of the EDJ shape for better informing fossil primate alpha-taxonomy by means of quantitatively testing hypotheses about tooth shape variation.

Clinical Success Evaluation of Ultrathin Ceramic Veneers Bonded to Nonprepared Teeth: An Observational Prospective Cohort Study.

Patients' increasing interest in achieving optimal cosmetic outcomes and the widespread use of ultrathin ceramic veneers offer advantages such as high esthetic results and long-term durability. Several issues related to tooth preparation have been raised, including dental sensitivity, periodontal diseases, and increased treatment phases, in addition to complications associated with previous procedures, the treatment of which remains controversial to date. With the advancement of dental ceramic and its manufacturing techniques, it was widely used to manufacture ultrathin ceramic veneers with minimal preparation. Issues such as fracture and abfraction are the most common in ceramic veneers made of feldspathic ceramic due to their weak mechanical properties against various forces, which led to the emergence of lithium disilicate glass-ceramic manufactured using the heat-press technique. This has resulted in ultrathin ceramic veneers with a thickness of up to 0.1-0.2 mm easily bonded and finished as they have high mechanical properties and esthetic qualities that mimic natural tooth color and shape. The current cohort study aimed to evaluate the success rates of this kind of treatment for patients treated at our department. This observational cohort study's sample comprised 60 ultrathin ceramic veneers manufactured from lithium disilicate glass-ceramic bonded to nonprepared upper teeth. The clinical performance of the studied sample was evaluated and monitored at monthly intervals (one month, three months, six months, and one year) using the clinical success evaluation based on Walton's principles adopted for evaluating the success and failure of fixed restorations. Ultrathin ceramic veneers made from lithium disilicate glass-ceramic, bonded to nonprepared teeth, proved to be a successful clinical and esthetic treatment option, with a clinical success rate of 100% during the entire follow-up period. This study's findings indicate that ultrathin ceramic veneers made from lithium disilicate glass-ceramic, bonded to nonprepared teeth, area successful clinical and esthetic treatment option, with a clinical success rate of 100% during the entire follow-up period.

Revealing the use of dental indices to infer taxonomic variation in sauropod dinosaurs

AbstractSauropod 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.

Finite element analysis & topology optimization of excavator bucket teeth for optimal performance

In the realm of heavy-duty machinery, excavators hold pivotal roles in construction, mining, and various large-scale projects. The excavator's efficacy relies significantly on its bucket teeth, crafted from robust materials like steel, crucial for soil and rock excavation. However, inadequacies in tooth shape and composition can lead to wear which in turn leads to diminished productivity. Employing finite element analysis, the present research delves into the influence of cantilever profile on TATA Hitachi Ex70 and JCB JS81 bucket teeth, using AISI 4340 and AISI 4140 materials, respectively. Analysing von Mises stress and deformation through Altair HyperMesh, subsequent Altair OptiStruct facilitates topology optimisation aims to reduce tooth mass. It appears that Tooth I (TATA Hitachi Ex70) experienced a decrease in mass, yet an elevation in von Mises stress compared to its initial mass of 2.81 kg and stress level of 1.74 E + 02 MPa. Similarly, Tooth II (JCB JS81) showcased a reduction in mass and a rise in von Mises stress from its original mass of 2.03 kg and stress of 1.038 E + 02 MPa. Validation of optimised designs through the graphs depicting the Factor of Safety (FOS) for both teeth ensures compliance with specified requirements, confirming that optimised excavator bucket teeth designs are safe.

Effects of Nail Biting (Onychophagy) on Upper Central Incisors in Children and Young Adolescents

Nail biting (NB) is a repetitive and uncontrolled parafunctional activity that can affect oral health by altering tooth shape and intraoral position. Nowadays, there is not enough scientific evidence about the impact of NB on teeth; therefore, this study aimed to evaluate the effects of NB on the length, width and inclination of upper central incisors. This retrospective study involved 76 patients, 40 males and 36 females, with a mean age of 10.6 ± 0.3 years. Digital scans of the maxillary arch of each patient were recorded. Next, the length, width and inclination of upper central incisors used and not used for NB were measured. Finally, data were analysed with a paired t-test. Statistical analysis showed statistically significant differences in the length and inclination of upper central incisors used for NB compared with those of upper central incisors not used for NB, while the width did not show a significant difference. There were relevant changes in upper central incisors subjected to NB, demonstrating that NB impairs the shape, morphology and inclination of teeth. Therefore, because of the potentially negative consequences of NB, it is recommended that NB not be underestimated.

Automatic 3D Teeth Reconstruction From Five Intra-Oral Photos Using Parametric Teeth Model.

Orthodontic treatment is a lengthy process that requires regular in-person dental monitoring, making remote dental monitoring a viable alternative when face-to-face consultation is not possible. In this study, we propose an improved 3D teeth reconstruction framework that automatically restores the shape, arrangement, and dental occlusion of upper and lower teeth from five intra-oral photographs to aid orthodontists in visualizing the condition of patients in virtual consultations. The framework comprises a parametric model that leverages statistical shape modeling to describe the shape and arrangement of teeth, a modified U-net that extracts teeth contours from intra-oral images, and an iterative process that alternates between finding point correspondences and optimizing a compound loss function to fit the parametric teeth model to predicted teeth contours. We perform a five-fold cross-validation on a dataset of 95 orthodontic cases and report an average Chamfer distance of 1.0121 mm2 and an average Dice similarity coefficient of 0.7672 on all the test samples in the cross-validation, demonstrating a significant improvement compared with the previous work. Our teeth reconstruction framework provides a feasible solution for visualizing 3D teeth models in remote orthodontic consultations.

Squamates as a model to understand key dental features of vertebrates

Thanks to their exceptional diversity, teeth are among the most distinctive features of vertebrates. Parameters such as tooth size, shape, number, identity, and implantation can have substantial implications for the ecology and certain social behaviors of toothed species. Despite decades of research primarily focused on mammalian dentition, particularly using the laboratory mouse model, squamate reptiles (“lizards” and snakes) offer a wide array of tooth types and dentition variations. This diversity, which includes differences in size, shape, function, and replacement capacity, provides invaluable opportunities for investigating these fundamental properties. The central bearded dragon (Pogona vitticeps), a popular pet species with well-established husbandry practices, is of particular interest. It features a broad spectrum of morphs and spontaneous mutants and exhibits a wide range of heterodont phenotypes, including variation in the size, shape, number, implantation, and renewal of teeth at both posterior and anterior positions. These characteristics position the species as a crucial model organism for developmental studies in tooth research and for gaining deeper insights into evolutionary patterns of vertebrate dentitions. In this article, we provide an overview of the current understanding of squamate dentition, its diversity, development, and replacement. Furthermore, we discuss the significant advantages offered by squamate species as model organisms for investigating the evolutionary and developmental aspects of vertebrate dentition.

Spiral-scanning electromagnetic heating of helical gears based on a coordinate system linkage method

In the field of electromagnetic heating, continuous scanning heating is one of the crucial approaches to minimizing the temperature distribution gradient in basic components such as helical gears. However, in the process of dynamic heating, the spiral tooth shape of helical gears complicates the coupling relationship between the induction coil and the gear. Therefore, the distribution mechanism of magneto-thermal properties is difficult to investigate. A new spiral scanning electromagnetic heating method for helical gears − Coordinate System Linkage Method (CSLM) −is proposed. To facilitate the precise movement of the profiling induction coil, we formulate a set of coordinate systems by integrating the spiral characteristics of the gear. The mathematical model is constructed by segmenting the spiral-scanning motion and delineating its interrelationships. On this basis, an electric–magnetic-thermal coupling model specific to spiral-scanning heating is enabled. For the process of spiral-scanning heating, two coil scanning methods are designed: “sudden speed change” and “gradual speed change”. A comparative study reveals the temperature difference along the tooth width with the “gradual speed change” method is smaller than that with the “sudden speed change” method. Moreover, controlling the coil scanning speed appropriately can minimize the temperature gradient of the entire gear, while changing the initial heating position of the coil can balance the end-face effect. Both of these measures effectively equalize the temperature distribution along the tooth width. Finally, an experimental platform for spiral scanning heating of the helical gear is constructed to confirm the correctness of the simulation results, which likewise demonstrates the effectiveness of the method in improving temperature uniformity. This study provides a measurable theoretical reference basis for the electromagnetic heat transfer of irregular workpieces with spiral features to accurately control the temperature gradient.

Sexual dimorphism in the dwarf round ray Urotrygon nana.

This paper presents information on the morphological, morphometric, and dental sex differences in the dwarf round ray Urotrygon nana. We recorded 12 morphological traits, sex, the distribution pattern of dermal denticles, the number of tooth rows, and the tooth shape of 466 individuals. The disc width of females ranged from 50 to 172 mm and that of males ranged from 53 to 135 mm. A neuronal classification model and a correspondence analysis showed that female disc width was 21.5% broader, and the distance from the rostrum to the anus was 17.7% longer than that of males, whereas males presented 19.5% greater distance between the nostrils, 9.7% greater preorbital snout length, 6.8% greater cloaca to caudal-fin length, 2.7% greater interorbital distance, and 1.1% greater total length than females. The disc of adult males, including the abdominal cavity area, was densely covered with dermal denticles, which were slightly larger than those observed in females. Females presented homodont dentition with molariform teeth and a smooth lozenge-shaped crown with rounded margins. Males exhibited homodonty but with tooth morphology variations in individuals of different sizes (from molariforms to sharper cusp teeth). There were changes in disc shape (from subcircular to oval), distribution and size of dermal denticles (more abundant and larger), and tooth shape (from molariform to monocuspid teeth) during male development, from neonates to adults. U. nana exhibited sexual dimorphism in size, disc shape, number and shape of teeth, and distribution and size of dermal denticles.

Thermodynamic Study on the Vortex Teeth of Electric Scroll Compressors Based on Gradient Tooth Height

Through the analysis of the adhesion between the tooth head and axial clearance leakage attributed to vortex tooth shape deformation, an innovative tooth shape design concept has been introduced entitled “progressive change tooth high vortex tooth”. This unique design includes a gradual change in tooth height and an elevated vortex tooth profile, using temperature-sensitive materials to enhance the resolution of temperature loading on the vortex disc. By refining the process of resolving the temperature loading on the vortex disc, the mean temperature function of the fluid domain along the wall of the vortex tooth is calculated, and a steady-state temperature distribution model for the solid domain of the vortex tooth is formulated. Subsequently, a finite element model for the high eddy current disc is constructed using Abaqus 2021 finite element software, which facilitates the calculation of stress–strain distribution within the high eddy current disc under both gas pressure and temperature field loads. The results show that, especially under conditions of low speed and low exhaust pressure, the temperature load mainly influences the maximum deformation and stress distribution of the vortex tooth. Specifically, under the influence of heat-solid coupling, the maximum deformation of the progressive change tooth high vortex tooth occurs in close proximity to the central compression cavity, reaching up to 13 microns. These results provide a crucial theoretical basis for the structural design and performance optimization of the compressor.

Full Digital Workflow for Aesthetic Rehabilitation of the Upper Teeth: A Case Report

The present case report presents a digital workflow for designing an aesthetic rehabilitation of the upper anterior teeth in an adult male. The patient suffered from a gummy smile resulting from an unfavorable ratio between upper lip length and gingiva/tooth display. In addition, the tooth shapes, color, and position were not accepted by the patient. The treatment planning included gingivectomy based on a digitally designed PMMA guide performed using a soft tissue SOGA laser (Shenzhen Soga Technology Co., Ltd., Shenzhen, China). The preparation was guided by the plastic guides for preparation control created digitally in Exocad software (Rijeka 3.1. Darmstadt, Germany) and printed in three-dimensional plastic. Next, both arches and maximum intercuspation were scanned. The milled lithium disilicate veneers were manufactured using CAD-computer-aided manufacturing (CAM) equipment. The restorations were cemented using a translucent light-cure resin cement (RelyX Universal, 3M ESPE, St. Paul, MN, USA). Next, occlusion adjustment and polishing were executed. Based on the present case report, it can be assumed that the application of digital techniques allows us to achieve an aesthetic and functional result with reduced work time and errors. Emphasizing the clinical impact, these methods enhance patient satisfaction and treatment accuracy in intricate aesthetic rehabilitations.

Rotor pole and stator tooth shaping in FSPM machines for torque performance optimization

Purpose This study aims to obtain the minimum torque ripple at the maximum average torque for Flux-switching permanent magnet (FSPM) machines. Design/methodology/approach This paper is about torque performance optimization of the FSPM machines. To achieve that, finite element analysis and genetic algorithm (GA) are used. Five different designs are simulated, optimized and compared on their air gap flux density, back electromotive force, cogging torque, average torque, torque density and torque ripple. Findings After the thousands of iterations, its proved that all proposed shaping techniques have potential for reducing torque ripple and cogging torque, with slightly reduced average torque. The best design is the joint stator and rotor shaping, Design V, which results in the lowest torque ripple and cogging torque. The techniques should be applicable to FSPMs with other stator slot/rotor pole number combinations. Originality/value In this paper, rotor pole shaping by notching, chamfering and generic shaping, stator tooth shaping and joint shaping techniques are investigated for 12 s/10p FSPM machines. Rotor and stator flanks are optimized separately and jointly, by using finite element analysis and GA for optimization to achieve maximum average torque and minimum torque ripple. Five different design is implemented and compared, respectively.

The chitons of the family Leptochitonidae (Mollusca: Polyplacophora) from the Emperor Seamounts, Pacific Ocean

A small number of chitons collected from three Emperor Seamounts was studied. Three species were identified. Of these, one species, Leptochiton milwaukensis n. sp., is new. The new species is distinguished by a unique sculpture of the central area of the intermediate valves, with narrowed pores of micraesthetes on the tegmentum granules and the shape of central teeth of the radula. For the first time three specimens of Belknapchiton belknapi were collected from the bathyal zone near the biogeographic border between the boreal and the tropical realms.