Search

Abstract Background With the development and utilization of three-dimensional (3D) intraoral scanning (IOS) technology, the morphological characteristics of teeth were quantitatively assessed. In this research, we aimed to explore the prevalence of dental caries in relation to each measurable morphological indicator of the tooth body via 3D intraoral scanning techniques. Methods A hospital-based single-centre study was conducted at our hospital from Dec. 2021 to Apr. 2023. A total of 53 patients were involved in the study, providing complete morphological data for 79 teeth. Each patient completed an oral hygiene routine questionnaire and underwent examination by an experienced dentist to evaluate caries conditions before undergoing 3D intraoral scanning to obtain a digital dental model. Geomagic Studio 2014 was used to extract oral morphological data from the models. The acquired data were entered, cleaned and edited using Excel 2016 and subsequently exported to SPSS version 25.0 for analysis. Chi-square analysis and logistic regression analyses were employed to test the associations. Results Among the participants, 33 (61.1%) were female, with a mean age of 26.52 ± 10.83 years. Significant associations were found between dental caries and the vertical distance between the distal tip and the gum (OR 14.02; 95% CI 1.80-109.07; P = 0.012), the distal lateral horizontal distance of occlusion (OR 0.40; 95% CI 0.18–0.90; P = 0.026), and the mesial horizontal distance of occlusion (OR 2.20; 95% CI 1.12–4.31; P = 0.021). The Hosmer–Lemeshow test indicated a P value of 0.33. Conclusions The vertical distance between the distal tip and the gum, the distal lateral horizontal distance of the occlusion and the mesial horizontal distance of the occlusion were the influencing factors for dental caries (identified as independent risk factors). We hypothesize that these factors may be associated with the physiological curvature of teeth and the role of chewing grooves in plaque formation over time. However, further studies involving larger population samples and more detailed age stratification are still needed.

Objective: Tooth morphology education is a critical component of dental curricula, providing a foundational understanding of the intricate structural anatomy of teeth. This study evaluates the learning outcomes in relation to tooth morphology of two student cohorts from different academic terms, comparing the traditional 'tooth puzzle' method to an alternative fully digital approach. Materials and Methods: Two groups of Master of Dentistry students were retrospectively analyzed. The control group (55 students) was taught via the 'tooth puzzle' method in 2021, while the experimental group (55 students) underwent a fully digital course in 2020 due to COVID-19 restrictions. Both groups completed a digital examination involving the identification of 40 teeth, presented as images and videos. Results: In the control group of 55 students, nearly half (49.1%) achieved faultless results, while 65.5% had at most two faults, and 74.5% had no more than four faults. The group had a total of 163 faults, averaging 3.0 per student, with only one student (1.8%) failing the test. In stark contrast, the experimental group had no students without faults, 9.1% had four or fewer faults, and a significant 61.8% made 10 or more faults, with 29.1% failing their first test attempt by exceeding 12 faults. Overall, the experimental group registered 582 faults, averaging 10.6 per student. Conclusions: The 'tooth puzzle' method, with its interactive and tactile elements, proved more effective in teaching tooth morphology than the digital-only approach. The increased number of faults and failed tests in the experimental group suggest that while digital tools offer meaningful support in learning tooth morphology, their main advantage is seen when coupled with traditional hands-on techniques, not unassisted and independently. [ABSTRACT FROM AUTHOR]

Introduction: The COVID‐19 pandemic brought major disruptions to dental teaching and has impacted the delivery of tooth morphology courses where students are introduced to the three‐dimensional features of the dentition. The aim of this study was to assess the implementation of newly developed online teaching modalities for tooth morphology, evaluate their usefulness and identify elements that are beneficial for learners. Materials and Methods: Following the delivery of an online course that included online 3D models, 2D cue cards, live discussion sessions and Socrative™ quizzes, the participants were asked to rate the usability and usefulness of each tool. The participants' knowledge of tooth morphology was assessed through an online examination using 3D‐digitised tooth models. Results: The participants identified lecture handouts and online 3D models as their preferred learning tools, while lecture video recordings and 2D cue cards were viewed as less useful. Data analysis from Socrative™ quizzes demonstrated improvement in tooth identification skills throughout the course delivery. Finally, results from the final assessment are in line with previous in‐person deliveries of this course. Conclusions: The study provides valuable information on the usefulness of teaching modalities that were implemented in response to the COVID‐19 pandemic and their merit to be retained in future deliveries of the course. The 3D models have been identified as particularly useful in this context, but the participants still value the opportunity to learn with extracted teeth. Furthermore, it remains to be confirmed whether tooth identification skills acquired using 3D models can be transferred to the clinical setting. [ABSTRACT FROM AUTHOR]

The pterosaur fossil record of Argentina is increasing in recent times, both in the number of localities and their temporal range. The new materials are found in levels that span from the Late Triassic to the Late Cretaceous in age. In this contribution we describe twenty isolated pterosaur teeth from the Cerro de los Leones locality (Picún Leufú, Neuquén Province), where the Lohan Cura Formation (Albian) widely crops out. A new, detailed analysis of these remains allowed us to detect a set of morphological features, such as the enamel texture, cross-section shape, crown curvature, and absence of sharp carinae, which suggests close affinities with Ornithocheiriformes. Moreover, with the large number of tooth specimens, a discrimination of three morphotypes based on the crown curvature, the basal cross-section shape, and the presence of carinae was carried out. We performed extensive morphological comparisons between different members of Ornithocheiriformes with the aim to test the hypothesis that the presence of these different morphotypes reflects distinct anatomical positions of the teeth in the jaws . Thus, considering the heterodont dentition of ornithocheiriforms, the tooth morphological classification proposed here represents a new methodology, not only to identify isolated ornithocheiriform teeth, but also to assign them to the rostral, medial, or the posterior portion of the tooth row. Finally, the evidence of ornithocheiriform pterosaurs in Cerro de los Leones has paleobiogeographical implications, allowing us to correlate it with other Albian faunas from South America, expanding our knowledge of the distribution of Early Cretaceous pterosaurs across southwestern Gondwana.

Purpose/objectives: Tooth carvings are evaluated subjectively. However, subjective evaluations are associated with low intra‐ and inter‐evaluator reliability in providing feedback for the fabrication of better tooth carvings. Therefore, this study aimed to analyze the relationship between subjective evaluation and the morphological characteristics of tooth carvings and their morphological characteristics using the feedback method in the low‐scoring group. Methods: Between April 2013 and September 2021, 120 maxillary left first molar carvings fabricated by undergraduate students were subjectively evaluated by an experienced instructor using a five‐point scale. The tooth carvings were scanned to obtain three‐dimensional shape data and divided into two groups, the high‐ and low‐scoring groups, for principal component analysis. Homologous models with dimensions matching those of the average model were created, and principal component analysis was performed to evaluate the morphological characteristics of the tooth. Results: Principal component analysis indicated that an objective evaluation was possible using homologous model. On increasing the subjective evaluation, the occlusal inclination angle and the cervical region of the tooth became steeper, and the shape of the occlusal surface resembled a parallelogram. In addition, large morphological differences were observed in the position of the cervical region of the tooth, height of contour, and shape of the occlusal surface in the low‐scoring group, whereas no such difference was observed in the high‐scoring group. Conclusion: Objective evaluation of tooth carving was possible using homologous model. The evaluation of tooth morphological characteristics could be effective in providing feedback to undergraduate students. [ABSTRACT FROM AUTHOR]

The pterosaur fossil record of Argentina is increasing in recent times, both in the number of localities and their temporal range. The new materials are found in levels that span from the Late Triassic to the Late Cretaceous in age. In this contribution we describe twenty isolated pterosaur teeth from the Cerro de los Leones locality (Picún Leufú, Neuquén Province), where the Lohan Cura Formation (Albian) widely crops out. A new, detailed analysis of these remains allowed us to detect a set of morphological features, such as the enamel texture, cross-section shape, crown curvature, and absence of sharp carinae, which suggests close affinities with Ornithocheiriformes. Moreover, with the large number of tooth specimens, a discrimination of three morphotypes based on the crown curvature, the basal cross-section shape, and the presence of carinae was carried out. We performed extensive morphological comparisons between different members of Ornithocheiriformes with the aim to test the hypothesis that the presence of these different morphotypes reflects distinct anatomical positions of the teeth in the jaws . Thus, considering the heterodont dentition of ornithocheiriforms, the tooth morphological classification proposed here represents a new methodology, not only to identify isolated ornithocheiriform teeth, but also to assign them to the rostral, medial, or the posterior portion of the tooth row. Finally, the evidence of ornithocheiriform pterosaurs in Cerro de los Leones has paleobiogeographical implications, allowing us to correlate it with other Albian faunas from South America, expanding our knowledge of the distribution of Early Cretaceous pterosaurs across southwestern Gondwana. [ABSTRACT FROM AUTHOR]

In forensic identification, lack of eccentric characteristics of intact dentitions hinders correct ante-mortem/post-mortem (AM/PM) matching. It remains unclear which morphological dental parameters hold strong potential as identifiers. This study aimed to establish a method to quantify and rank the identifying potential of one (or a combination of) continuous morphological parameter(s), and to provide a proof of concept. First, a statistic was defined that quantifies the identifying potential: the mean potential set (MPS). The MPS is derived from inter-observer agreement data and it indicates the percentage of subjects in the AM reference dataset who at least need to be considered to detect the correct PM subject. This was calculated in a univariate and a multivariate setting. Second, the method was validated on maxillary first molar crowns of 82 3D-digitally scanned cast models. Standardized measurements were registered using 3D modeling software (3-Matic Medical 12.0, Materialise N.V., Leuven, Belgium): tooth depth, angles between cusps, distances between cusps, distances between the cusps, and the mesial pit. A random sample of 40 first molars was measured by a second examiner. Quantifying and ranking the parameters allowed selecting those with the strongest identifying potential. This was found for the tooth depth (1 measurement, MPS = 17.1%, ICC = 0.879) in the univariate setting, and the angles between cusps (4 measurements, MPS = 3.9%) in the multivariate setting. As expected, the multivariate approach held significantly stronger identifying potential, but more measurements were needed (i.e., more time-consuming). Our method allows quantifying and ranking the potential of dental morphological parameters as identifiers using a clear-cut statistic. [ABSTRACT FROM AUTHOR]

The nitrogen isotopic composition (15N/14N ratio, or δ15N) of enameloid‐bound organic matter (δ15NEB) in shark teeth was recently developed to investigate the biogeochemistry and trophic structures (i.e., food webs) of the ancient ocean. Using δ15NEB, we present the first nitrogen isotopic evidence for trophic differences between shark taxa from a single fossil locality. We analyze the teeth of four taxa (Meristodonoides, Ptychodus, Scapanorhynchus, and Squalicorax) from the Late Cretaceous (83–84 Ma) Trussells Creek site in Alabama, USA, and compare the N isotopic findings with predictions from tooth morphology, the traditional method for inferring shark paleo‐diets. Our δ15NEB data indicate two distinct trophic groups, with averages separated by 6.1 ± 2.1‰. The lower group consists of Meristodonoides and Ptychodus, and the higher group consists of Scapanorhynchus and Squalicorax (i.e., lamniforms). This δ15NEB difference indicates a 1.5 ± 0.5 trophic‐level separation between the two groups, a finding that is in line with paleontological predictions of a higher trophic level for these lamniforms over Meristodonoides and Ptychodus. However, the δ15NEB of Meristodonoides is lower than suggested by tooth morphology, although consistent with mechanical tests suggesting that higher trophic‐level bony fishes were not a major component of their diet. Further, δ15NEB indicates that the two sampled lamniform taxa fed at similar trophic levels despite their different inferred tooth functions. These two findings suggest that tooth morphology alone may not always be a sufficient indicator of dietary niche. The large trophic separation revealed by the δ15NEB offset leaves open the possibility that higher trophic‐level lamniforms, such as those measured here, preyed upon smaller, lower trophic‐level sharks like Meristodonoides. [ABSTRACT FROM AUTHOR]

Producing tooth crowns through dental technology is a basic function of dentistry. The morphology of tooth crowns is the most important parameter for evaluating its acceptability. The procedures were divided into four steps: tooth collection, scanning skills, use of mathematical methods and software, and machine learning calculation. Dental plaster rods were prepared. The effective data collected were to classify 121 teeth (15th tooth position), 342 teeth (16th tooth position), 69 teeth (21st tooth position), and 89 teeth (43rd tooth position), for a total of 621 teeth. The procedures are divided into four steps: tooth collection, scanning skills, use of mathematical methods and software, and machine learning calculation. The area under the curve (AUC) value was 0, 0.5, and 0.72 in this study. The precision rate and recall rate of micro-averaging/macro-averaging were 0.75/0.73 and 0.75/0.72. If we took a newly carved tooth picture into the program, the current effectiveness of machine learning was about 70%–75% to evaluate the quality of tooth morphology. Through the calculation and analysis of the two different concepts of micro-average/macro-average and AUC, similar values could be obtained. This study established a set of procedures that can judge the quality of hand-carved plaster sticks and teeth, and the accuracy rate is about 70%–75%. It is expected that this process can be used to assist dental technicians in judging the pros and cons of hand-carved plaster sticks and teeth, so as to help dental technicians to learn the tooth morphology more effectively. [ABSTRACT FROM AUTHOR]

Modern sharks have an evolutionary history of at least 250 million years and are known to play key roles in marine systems, from controlling prey populations to connecting habitats across oceans. These ecological roles can be quantified based on their functional traits, which are typically morphological (e.g., body size) or behavioural (e.g., feeding and diet). Nonetheless, the understanding of such roles of extinct sharks is limited due to the inherent incompleteness of their fossil record, which consists mainly of isolated teeth. As such, establishing links between tooth morphology and ecological traits in living sharks could provide a useful framework to infer sharks' ecology from the fossil record. Here, based on extant sharks from which morphological and behavioural characteristics are known, the authors assess the extent to which isolated teeth can serve as proxies for functional traits. To do so, they first review the scientific literature on extant species to evaluate the use of shark dental characters as proxies for ecology to then perform validation analyses based on an independent data set collected from museum collections. Their results reveal that 12 dental characters have been used in shark literature as proxies for three functional traits: body size, prey preference and feeding mechanism. From all dental characters identified, tooth size and cutting edge are the most widely used. Validation analyses suggest that seven dental characters – crown height, crown width, cutting edge, lateral cusplets, curvature, longitudinal outline and cross‐section outline – are the best proxies for the three functional traits. In particular, tooth size (crown height and width) was found to be a reliable proxy of all three traits; the presence of serrations on the cutting edge was one of the best proxies for prey preference; and tooth shape (longitudinal outline) and the presence of lateral cusplets were among the best indicators of feeding mechanism. Overall, the authors' results suggest that in the absence of directly measurable traits in the fossil record, these seven dental characters (and different combinations of them) can be used to quantify the ecological roles of extinct sharks. This information has the potential to provide key insights into how shark functional diversity has changed through time, including their ecological responses to extinction events. [ABSTRACT FROM AUTHOR]

Objective: Tooth morphology education is a critical component of dental curricula, providing a foundational understanding of the intricate structural anatomy of teeth. This study evaluates the learning outcomes in relation to tooth morphology of two student cohorts from different academic terms, comparing the traditional ‘tooth puzzle’ method to an alternative fully digital approach. Materials and Methods: Two groups of Master of Dentistry students were retrospectively analyzed. The control group (55 students) was taught via the ‘tooth puzzle’ method in 2021, while the experimental group (55 students) underwent a fully digital course in 2020 due to COVID-19 restrictions. Both groups completed a digital examination involving the identification of 40 teeth, presented as images and videos. Results: In the control group of 55 students, nearly half (49.1%) achieved faultless results, while 65.5% had at most two faults, and 74.5% had no more than four faults. The group had a total of 163 faults, averaging 3.0 per student, with only one student (1.8%) failing the test. In stark contrast, the experimental group had no students without faults, 9.1% had four or fewer faults, and a significant 61.8% made 10 or more faults, with 29.1% failing their first test attempt by exceeding 12 faults. Overall, the experimental group registered 582 faults, averaging 10.6 per student. Conclusions: The ‘tooth puzzle’ method, with its interactive and tactile elements, proved more effective in teaching tooth morphology than the digital-only approach. The increased number of faults and failed tests in the experimental group suggest that while digital tools offer meaningful support in learning tooth morphology, their main advantage is seen when coupled with traditional hands-on techniques, not unassisted and independently.

Abstract Background Augmented reality (AR) technology has been shown to be effective in displaying information and presenting three-dimensional objects. Although AR applications are commonly used by learners via mobile devices, plastic models or two-dimensional images are still commonly used in tooth carving practice. Learners practicing tooth carving face a challenge due to the three-dimensional features of teeth as there is a lack of tools available that provide sequential guidance. In this study, we developed an AR-based tooth carving practice tool (AR-TCPT) and compared it to a plastic model to evaluate its potential as a practice tool as well as its user experience. Methods To model tooth carving, we created a three-dimensional object from sequential steps that included the maxillary canines and maxillary first premolars (16 steps), mandibular first premolars (13 steps), and mandibular first molars (14 steps). Image markers, created using Photoshop software, were assigned to each tooth. An AR-based mobile application was developed using the Unity engine. For tooth carving, 52 participants were randomly assigned to a control group (n = 26; using a plastic tooth model) or an experimental group (n = 26; using the AR-TCPT). User experience was evaluated using a 22-item questionnaire. Data were comparatively analyzed using the nonparametric Mann–Whitney U test via the SPSS program. Results The AR-TCPT detects image markers with the mobile device camera and displays three-dimensional objects for tooth fragmentation. Users can manipulate the device to view each step or examine the shape of a tooth. The results of the user experience survey revealed that the AR-TCPT experimental group scored significantly higher in tooth carving experience compared with the control group that used the plastic model. Conclusion Compared with the conventional plastic model, the AR-TCPT provided a better user experience for tooth carving. The tool is highly accessible as it is designed to be used on mobile devices by users. Further studies are required to determine the educational impact of the AR-TCTP on quantitative scoring of carved teeth as well as individual user’s carving abilities.

Abstract Background There have been reports of unique dental morphological features amongst Latin American and Hispanic populations, and this might invalidate the use of current orthodontic diagnostic tools within this population. There are no tooth size/tooth ratio normative standards for the Hispanic population, despite overwhelming evidence about differences in tooth size between racial groups. Objective This study aimed to determine whether there are significant differences in 3-D tooth shape between patients with Angle Class I, Class II, and Class III dental malocclusion in the Hispanic population. Methodology Orthodontic study models representing Hispanic orthodontic patients with Angle Class I, II, and III dental malocclusions scanned using an intra-oral scanner. The scanned models were digitized and transferred to a geometric morphometric system. Tooth size shape were determined, quantified, and visualized using contemporary geometric morphometric computational tools using MorphoJ software. General Procrustes Analysis (GPA) and canonical variates analysis (CVA) used to delineate the features of shape that are unique to each group. Result The study revealed differences in tooth shape between the different dental malocclusion groups on all twenty-eight teeth that were studied; the pattern of shape differences varied between the teeth and the dental malocclusions. The MANOVA test criteria, F approximations, and P-values show that shape in all the groups was significantly different

Introduction: The gingival phenotype (GP) of teeth at the aesthetic zone often influences dental rehabilitation plans and treatment outcomes. This study aimed to assess the prevalence of GP in the Malay population in relation to gender and age. Methods: The GP of 100 patients were determined using the Probe test method. Other clinical parameters were assessed include crown width/crown length (CW/CL) ratio, tooth morphology and width of keratinised tissue. Periodontal parameters were assessed by two calibrated examiners. Data were analysed using descriptive statistics, one-way ANOVA and Kruskal-Wallis test. Results: A higher prevalence of thick GP was found at the maxilla for both genders, whereas a thin phenotype was observed at the mandible. At maxilla, both thick and thin GP were found in all age groups, while the mandible showed a higher prevalence of thin GP. Significant differences in GP were found between males and females for mandibular and maxillary anterior teeth and the mandibular lateral incisor (p<0.05), while no significant difference was found for other parameters assessed; age group, CW/CL, tooth morphology and WKT. Conclusion: Thicker GP is more prevalent in male population and at maxillary anterior. Mandibular anterior GP presented commonly with a thin GP regardless of gender or age-group. [ABSTRACT FROM AUTHOR]

Copyright of Collegium Antropologicum is the property of Croatian Anthropological Society 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: Augmented reality (AR) technology has been shown to be effective in displaying information and presenting three-dimensional objects. Although AR applications are commonly used by learners via mobile devices, plastic models or two-dimensional images are still commonly used in tooth carving practice. Learners practicing tooth carving face a challenge due to the three-dimensional features of teeth as there is a lack of tools available that provide sequential guidance. In this study, we developed an AR-based tooth carving practice tool (AR-TCPT) and compared it to a plastic model to evaluate its potential as a practice tool as well as its user experience. Methods: To model tooth carving, we created a three-dimensional object from sequential steps that included the maxillary canines and maxillary first premolars (16 steps), mandibular first premolars (13 steps), and mandibular first molars (14 steps). Image markers, created using Photoshop software, were assigned to each tooth. An AR-based mobile application was developed using the Unity engine. For tooth carving, 52 participants were randomly assigned to a control group (n = 26; using a plastic tooth model) or an experimental group (n = 26; using the AR-TCPT). User experience was evaluated using a 22-item questionnaire. Data were comparatively analyzed using the nonparametric Mann–Whitney U test via the SPSS program. Results: The AR-TCPT detects image markers with the mobile device camera and displays three-dimensional objects for tooth fragmentation. Users can manipulate the device to view each step or examine the shape of a tooth. The results of the user experience survey revealed that the AR-TCPT experimental group scored significantly higher in tooth carving experience compared with the control group that used the plastic model. Conclusion: Compared with the conventional plastic model, the AR-TCPT provided a better user experience for tooth carving. The tool is highly accessible as it is designed to be used on mobile devices by users. Further studies are required to determine the educational impact of the AR-TCTP on quantitative scoring of carved teeth as well as individual user's carving abilities. [ABSTRACT FROM AUTHOR]

Background: There have been reports of unique dental morphological features amongst Latin American and Hispanic populations, and this might invalidate the use of current orthodontic diagnostic tools within this population. There are no tooth size/tooth ratio normative standards for the Hispanic population, despite overwhelming evidence about differences in tooth size between racial groups. Objective: This study aimed to determine whether there are significant differences in 3-D tooth shape between patients with Angle Class I, Class II, and Class III dental malocclusion in the Hispanic population. Methodology: Orthodontic study models representing Hispanic orthodontic patients with Angle Class I, II, and III dental malocclusions scanned using an intra-oral scanner. The scanned models were digitized and transferred to a geometric morphometric system. Tooth size shape were determined, quantified, and visualized using contemporary geometric morphometric computational tools using MorphoJ software. General Procrustes Analysis (GPA) and canonical variates analysis (CVA) used to delineate the features of shape that are unique to each group. Result: The study revealed differences in tooth shape between the different dental malocclusion groups on all twenty-eight teeth that were studied; the pattern of shape differences varied between the teeth and the dental malocclusions. The MANOVA test criteria, F approximations, and P-values show that shape in all the groups was significantly different < 0.05. Conclusion: This study revealed differences in tooth shape between the different dental malocclusions on all teeth, and the pattern of shape differences varied between the different dental malocclusions group. [ABSTRACT FROM AUTHOR]

Objectives: Dental caries is a widespread multifactorial disease, caused by the demineralization of hard dental tissues. Susceptibility to dental caries is partially genetically conditioned; this study was aimed at finding an association of selected single nucleotide polymorphisms (SNPs) in genes encoding proteins involved in amelogenesis with this disease in children. Materials and methods: In this case–control study, 15 SNPs in ALOX15, AMBN, AMELX, KLK4, TFIP11, and TUFT1 genes were analyzed in 150 children with primary dentition and 611 children with permanent teeth with/without dental caries from the European Longitudinal Study of Pregnancy and Childhood (ELSPAC) cohort. Results: Dental caries in primary dentition was associated with SNPs in AMELX (rs17878486) and KLK4 (rs198968, rs2242670), and dental caries in permanent dentition with SNPs in AMELX (rs17878486) and KLK4 (rs2235091, rs2242670, rs2978642), (p ≤ 0.05). No significant differences between cases and controls were observed in the allele or genotype frequencies of any of the selected SNPs in ALOX15, AMBN, TFIP11, and TUFT1 genes (p > 0.05). Some KLK4 haplotypes were associated with dental caries in permanent dentition (p ≤ 0.05). Conclusions: Based on this study, we found that although the SNPs in AMELX and KLK4 are localized in intronic regions and their functional significance has not yet been determined, they are associated with susceptibility to dental caries in children. Clinical relevance: AMELX and KLK4 variants could be considered in the risk assessment of dental caries, especially in permanent dentition, in the European Caucasian population. [ABSTRACT FROM AUTHOR]

The Longipterygidae are a unique clade among the enantiornithines in that they exhibit elongate rostra (≥60% total skull length) with dentition restricted to the distal tip of the rostrum, and pedal morphologies suited for an arboreal lifestyle (as in other enantiornithines). This suite of features has made interpretations of this group’s diet and ecology difficult to determine due to the lack of analogous taxa that exhibit similar morphologies together. Many extant bird groups exhibit rostral elongation, which is associated with several disparate ecologies and diets (e.g., aerial insectivory, piscivory, terrestrial carnivory). Thus, the presence of rostral elongation in the Longipterygidae only somewhat refines trophic predictions of this clade. Anatomical morphologies do not function singularly but as part of a whole and thus, any dietary or ecological hypothesis regarding this clade must also consider other features such as their unique dentition. The only extant group of dentulous volant tetrapods are the chiropterans, in which tooth morphology and enamel thickness vary depending upon food preference. Drawing inferences from both avian bill proportions and variations in the dental morphology of extinct and extant taxa, we provide quantitative data to support the hypothesis that the Longipterygidae were animalivorous, with greater support for insectivory. [ABSTRACT FROM AUTHOR]

Natural Trap Cave is an enigmatic site in Wyoming that has been accumulating fossils for tens of thousands of years from animals falling into it. One of the more common taxa present at this site are horses. North American equids have been separated into two main groups: caballine "stout legged" horses, which include the modern Equus ferus caballus ; and the extinct non-caballine so-called "New World Stilt Legged" horses, which possess more gracile distal limb elements than modern horses. Genetic evidence has shown that both taxa are present at the Natural Trap Cave site. While post-cranial elements of both have been found, the most common horse specimens recovered have been isolated teeth, which have historically been difficult to identify to a specific taxon, though recent studies have been successful using geometric morphometrics on the occlusal surfaces of cheek teeth to differentiate equid taxa and populations. This study also uses geometric morphometrics to attempt to differentiate upper cheek tooth specimens between caballine and non-caballine stilt legged horses from Natural Trap Cave. Two landmark schemes were employed, one with fewer landmarks, and one with greater coverage, including sliding semi-landmarks. These schemes were used first on a dataset of only known specimens that had been taxonomically identified, and then unknown specimens from Natural Trap Cave were added. These analyses showed that the two taxa do indeed occupy statistically significant different areas of morphospace, as do premolars and molars. Surprisingly, the smaller landmark scheme produced better resolution on the Principal Components Analysis plots, possibly because the larger landmark scheme introduced ontogenetic variation due to different levels of tooth wear. While definitive identification does not seem advisable with this methodology, the unknown specimens grouped more with the known stilt legged specimens, suggesting that this taxon was more prevalent at Natural Trap Cave than the caballine Equus. [ABSTRACT FROM AUTHOR]

Objectives: Extended reality as an additional digital learning concept comprises virtual reality (VR), augmented reality, and mixed reality. In particular, VR allows an interaction in the virtual world. The aim of this study was to evaluate the students' attitude toward a mobile VR application for teaching tooth morphologies. Methods: Eighty‐two first year dental students were enrolled. After using the VR learning environment with mobile VR glasses at home for 1 week, the students were asked to fill in a questionnaire with 21 questions regarding intuitive handling, and supplemental learning information in comparison to the use of conventional textbooks. Nine questions provided predefined answer options, another nine had the form of a visual analog scale (VAS, range 0%‐highly negative to 100%‐highly positive), and three allowed free text answers. The data were checked for normal distribution (Kolmogorov‐Smirnov test) and was analyzed descriptively. Results: Forty‐four percent of the students rated their perception of understanding of dental morphologies much better with VR than with conventional learning. The potential of the VR learning environment for further dental topics was assessed with a median VAS score of 75.8%. Its intuitive handling was evaluated with a median VAS score of 67.1%. The haptic, visual, and auditory supplemental learning information was consistently rated positively with VAS scores of 73.9%, 80.0%, and 71.6%, respectively. Overall, a majority of the students (85.5%) recommended the VR learning environment for dental morphology. Conclusions: The VR dental learning environment allows dental students an additional learning opportunity of dental morphologies, recommended by more than 85% of students. [ABSTRACT FROM AUTHOR]

The discovery of odontogenic mechanisms essential for regenerating dental tissues and eventually developing a biomimetic artificial whole tooth for replacement is an ongoing aspiration for dental clinicians and researchers. Studying the diversity, development and evolutionary changes of mammalian dentitions can provide key insights into the mechanisms of odontogenesis that can be harnessed for regenerative dental medicine. A myriad of influences is expected to have shaped the dentitions of mammals and our objective is to highlight the contributions of phylogeny, functional adaptation, and development to tooth shape. Innovations in tooth shape analysis will be discussed, such as in imaging methodologies and quantitative comparisons, molecular biology approaches to phylogeny and the ontogenetic basis of tooth form. Study of the inter- and intra-species differences in tooth form as well as dental anomalies has provided clues toward the mechanisms of evolutionary change in dental form. Thus, phenotypic variation in tooth shape will also be discussed, including the role of development in creating tooth shape differences that evolutionary selection pressures may act upon. Functional adaptations have occurred in the context of the phylogenetic signal of primitive mammals, and predecessors to each phylogenetic branch, and examples will be discussed within members of the Order Carnivora, the Superfamily Suoidea and the Order Primates. The comparative study of mammalian tooth shape holds the potential to inform dental research areas, such as etiopathogeneses of dental variation and tooth shape anomalies, molecular mechanisms of tooth development and functional issues. Ultimately, insights from these research areas can be potentially translated for futuristic clinical applications like regeneration of various tooth tissue layers and eventually full tooth replacement.

The Longipterygidae are a unique clade among the enantiornithines in that they exhibit elongate rostra (≥60% total skull length) with dentition restricted to the distal tip of the rostrum, and pedal morphologies suited for an arboreal lifestyle (as in other enantiornithines). This suite of features has made interpretations of this group’s diet and ecology difficult to determine due to the lack of analogous taxa that exhibit similar morphologies together. Many extant bird groups exhibit rostral elongation, which is associated with several disparate ecologies and diets (e.g., aerial insectivory, piscivory, terrestrial carnivory). Thus, the presence of rostral elongation in the Longipterygidae only somewhat refines trophic predictions of this clade. Anatomical morphologies do not function singularly but as part of a whole and thus, any dietary or ecological hypothesis regarding this clade must also consider other features such as their unique dentition. The only extant group of dentulous volant tetrapods are the chiropterans, in which tooth morphology and enamel thickness vary depending upon food preference. Drawing inferences from both avian bill proportions and variations in the dental morphology of extinct and extant taxa, we provide quantitative data to support the hypothesis that the Longipterygidae were animalivorous, with greater support for insectivory.

Often the first point of contact between predator and prey, mammalian canine teeth are essential for killing, dismembering and consuming prey. Yet despite their importance, few associations among shape, function and phylogeny are established. We undertook the first comprehensive analysis of canine tooth shape across predatory mammals (Carnivora, Didelphimorphia and Dasyuromorphia), integrating shape analysis with function of this fundamental feature. Shape was quantified using three-dimensional geometric morphometrics and cross-sectional sharpness. Canines vary in three main ways (sharpness, robustness and curvature) which vary with diet, killing behaviour and phylogeny. Slender, sharp canines are associated with carnivores such as felids that target the neck of their prey and primarily consume the 'softer' parts of a carcass. Robust, blunt canines are found in mustelids and dasyurids that typically consume 'harder' materials, such as bone, or bite into skulls. Differences in the killing behaviours of felids and canids probably result in more curved canines in the latter, which act as hooks to hold prey. We find functional specialization in the upper and lower canines of individuals and across the major mammalian clades. These patterns demonstrate how canine teeth are adapted to suit diverse diets and hunting styles, enabling mammals to become some of nature's most successful predators. [ABSTRACT FROM AUTHOR]

Canine teeth are vital to carnivore feeding ecology, facilitating behaviours related to prey capture and consumption. Forms vary with specific feeding ecologies; however, the biomechanics that drive these relationships have not been comprehensively investigated. Using a combination of beam theory analysis (BTA) and finite-element analysis (FEA) we assessed how aspects of canine shape impact tooth stress, relating this to feeding ecology. The degree of tooth lateral compression influenced tolerance of multidirectional loads, whereby canines with more circular cross-sections experienced similar maximum stresses under pulling and shaking loads, while more ellipsoid canines experienced higher stresses under shaking loads. Robusticity impacted a tooth's ability to tolerate stress and appears to be related to prey materials. Robust canines experience lower stresses and are found in carnivores regularly encountering hard foods. Slender canines experience higher stresses and are associated with carnivores biting into muscle and flesh. Curvature did not correlate with tooth stress; however, it did impact bending during biting. Our simulations help identify scenarios where canine forms are likely to break and pinpoint areas where this breakage may occur. These patterns demonstrate how canine shape relates to tolerating the stresses experienced when killing and feeding, revealing some of the form–function relationships that underpin mammalian carnivore ecologies.

The C-shaped configuration of the root and root canal system is an unusual anatomical variation in mandibular first and second premolars. It is categorised as a 'C' due to the transverse morphology of the root and the root canal. The main anatomical characteristic is the presence of an invagination groove caused by Hertwig epithelial sheath faults during root development. This case report describes the root canal treatment of a C-shaped configuration of a mandibular first premolar, identified by means of cone beam computed tomography. [ABSTRACT FROM AUTHOR]

Aim: Presentation and discussion of orthodontic-endodontic treatment of a maxillary central incisor diagnosed with infected dens invaginatus (Oehlers' type III) and associated apical periodontitis utilising ultrasonic and hand instruments and the surgical operating microscope as an auxiliary tool for both diagnosis and treatment planning. Materials and methods: This case report describes the diagnosis and conservative treatment of a unilateral case of a maxillary central incisor with an infected type III dens invaginatus and an associated periradicular lesion followed of an orthodontic movement. Results: At the 1-year follow-up examination, clinical and radiographic findings showed that a diligent nonsurgical root canal treatment resulted in satisfactory periradicular healing. Conclusions: The present report demonstrates successful nonsurgical treatment of tooth with a challenging anatomy using contemporary techniques and materials. [ABSTRACT FROM AUTHOR]

Shark populations that are distributed alongside a latitudinal gradient often display body size differences at sexual maturity and vicariance patterns related to their number of tooth files. Previous works have demonstrated that Scyliorhinus canicula populations differ between the northeastern Atlantic Ocean and the Mediterranean Sea based on biological features and genetic analysis. In this study, we sample more than 3,000 teeth from 56 S. canicula specimens caught incidentally off Roscoff and Banyuls-sur-Mer. We investigate population differences based on tooth shape and form by using two approaches. Classification results show that the classical geometric morphometric framework is outperformed by an original Random Forests-based framework. Visually, both S. canicula populations share similar ontogenetic trends and timing of gynandric heterodonty emergence but the Atlantic population has bigger, blunter teeth, and less numerous accessory cusps than the Mediterranean population. According to the models, the populations are best differentiated based on their lateral tooth edges, which bear accessory cusps, and the tooth centroid sizes significantly improve classification performances. The differences observed are discussed in light of dietary and behavioural habits of the populations considered. The method proposed in this study could be further adapted to complement DNA analyses to identify shark species or populations based on tooth morphologies. This process would be of particular interest for fisheries management and identification of shark fossils. [ABSTRACT FROM AUTHOR]

The role dentition plays in shaping feeding patterns has significant consequences for understanding the evolution of shark feeding. Despite this, research has generally failed to compare tooth morphology and feeding ecology in elasmobranchs. For this reason, the diet and dentition of 120 Triakis megalopterus were examined from three study sites in southern Africa. Teleosts and crustaceans dominated the prey categories of T. megalopterus in Angola, and the Eastern Cape, respectively. Individuals from the Western Cape, however, fed almost exclusively on Jasus lalandii (%N > 98.1). This suggests that T. megalopterus may employ flexible foraging tactics to exploit abundant prey. Despite substantial dietary differences by region, the dentition of T. megalopterus remained remarkably similar amongst populations. This species possesses an anterior plate-like dentition with posterior teeth that rise into a short but sharp cusp, consistent with a trophic generalist. It is hypothesized that T. megalopterus employs a suction feeding mechanism while depressing and rotating these cusps, forming a plate-like grasping surface, thus avoiding tooth damage when feeding on crustaceans. Despite regional dental homology, a strong correlation exists between the feeding habits and dental divergence of this species throughout ontogeny. Small T. megalopterus have dorsoventrally flattened, more molariform lateral teeth which increase in area and width from small to large specimens, while the medial-inferior and medial-superior teeth lengthen producing a single cusp. The ontogenetic variation in dietary composition (increasing importance of cephalopods with size) appeared to be facilitated by this cusp development for grasping and/or manipulating soft-bodied prey. [ABSTRACT FROM AUTHOR]

Objectives: To compare implant supported crowns (ISCs) designed using deep learning (DL) software with those designed by a technician using conventional computer-aided design software., Methods: Twenty resin-based partially edentulous casts (maxillary and mandibular) used for fabricating ISCs were evaluated retrospectively. ISCs were designed using a DL-based method with no modification of the as-generated outcome (DB), a DL-based method with further optimization by a dental technician (DM), and a conventional computer-aided design method by a technician (NC). Time efficiency, crown contour, occlusal table area, cusp angle, cusp height, emergence profile angle, occlusal contacts, and proximal contacts were compared among groups. Depending on the distribution of measured data, various statistical methods were used for comparative analyses with a significance level of 0.05., Results: ISCs in the DB group showed a significantly higher efficiency than those in the DM and NC groups (P ≤ 0.001). ISCs in the DM group exhibited significantly smaller volume deviations than those in the DB group when superimposed on ISCs in the NC group (DB-NC vs. DM-NC pairs, P ≤ 0.008). Except for the number and intensity of occlusal contacts (P ≤ 0.004), ISCs in the DB and DM groups had occlusal table areas, cusp angles, cusp heights, proximal contact intensities, and emergence profile angles similar to those in the NC group (P ≥ 0.157)., Conclusions: A DL-based method can be beneficial for designing posterior ISCs in terms of time efficiency, occlusal table area, cusp angle, cusp height, proximal contact, and emergence profile, similar to the conventional human-based method., Clinical Significance: A deep learning-based design method can achieve clinically acceptable functional properties of posterior ISCs. However, further optimization by a technician could improve specific outcomes, such as the crown contour or emergence profile angle., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Shark populations that are distributed alongside a latitudinal gradient often display body size differences at sexual maturity and vicariance patterns related to their number of tooth files. Previous works have demonstrated that Scyliorhinus canicula populations differ between the northeastern Atlantic Ocean and the Mediterranean Sea based on biological features and genetic analysis. In this study, we sample more than 3,000 teeth from 56 S. canicula specimens caught incidentally off Roscoff and Banyuls-sur-Mer. We investigate population differences based on tooth shape and form by using two approaches. Classification results show that the classical geometric morphometric framework is outperformed by an original Random Forests-based framework. Visually, both S. canicula populations share similar ontogenetic trends and timing of gynandric heterodonty emergence but the Atlantic population has bigger, blunter teeth, and less numerous accessory cusps than the Mediterranean population. According to the models, the populations are best differentiated based on their lateral tooth edges, which bear accessory cusps, and the tooth centroid sizes significantly improve classification performances. The differences observed are discussed in light of dietary and behavioural habits of the populations considered. The method proposed in this study could be further adapted to complement DNA analyses to identify shark species or populations based on tooth morphologies. This process would be of particular interest for fisheries management and identification of shark fossils.

This study was performed to report the dental abnormalities encountered in immature dogs with a history of mandibular fracture. Dogs were included in the study if mandibular fractures were diagnosed by means of oral examination and diagnostic imaging, they were treated with non-invasive or minimally invasive methods, and there was a follow-up examination of at least 90 days after the initial presentation with the last follow-up visit occurring at 6 months of age or older. Eleven dogs met the inclusion criteria. Dental abnormalities occurred exclusively in those dogs that had sustained fracture of the mandibular body or fracture at the transition of mandibular body and mandibular ramus. A high number of developing permanent teeth located in or near the mandibular fracture were affected (73.5%). The most common dental abnormalities were failure of eruption or partial eruption (29.0%), resorption (22.6%), abnormal shape (19.4%), and enamel hypoplasia (16.1%). The majority of deciduous teeth (64.3%) in or near the mandibular fracture exfoliated uneventfully. Ten out of 11 dogs needed a surgical procedure to treat dental abnormalities after mandibular fracture healing. The development of the tooth germs located in or near a mandibular fracture is frequently affected. Radiographic evaluation of the area of trauma is recommended until eruption and full development of the teeth are completed. [ABSTRACT FROM AUTHOR]

This study assessed the effect of the course cycle on theoretical knowledge of dental morphology and the dental carving ability of dental students. Thirty‐two dental students from the third semester (initial cycle) and 30 students from the eighth and tenth semesters of the dental course (end cycle) had their theoretical knowledge on dental morphology assessed using a questionnaire with ten closed questions. Their dental carving ability was also assessed using wax carvings in macro models of plaster (for the third [S3] and eight [S8] semesters) and natural‐sized artificial teeth (for the tenth [S10] semester). The teeth chosen for the dental carving activity were #16 and #47. The scores were statistically analyzed using the t‐test, Kruskal–Wallis test, and Mann–Whitney test (α = 0.05). Students from the initial cycle presented better theoretical knowledge than the other groups did (P < 0.007). No significant differences in carving score were found between the initial and end cycles (P > 0.05), although S10 students obtained a higher score for teeth #16 and #47 (P < 0.05). Natural‐sized artificial teeth received a higher evaluation score in dental carvings than the macro models (P < 0.001). Within the limits of this study, it was possible to conclude that students from the initial cycle (S3) presented higher theoretical knowledge, whereas no difference in carving ability was observed between the initial and end cycles. The tenth semester (S10) students performed dental carvings with better quality. Furthermore, carvings in natural‐sized artificial teeth presented better quality compared with the macro models. [ABSTRACT FROM AUTHOR]

Objective: To determine the frequency of the number of roots and root canals in a sample of 250 extracted maxillary first premolar teeth of patients visiting Peshawar Dental College and Hospital Khyber Pakhtunkhwa. Study Design: Cross Sectional. Setting: Department of Oral Biology, Peshawar Dental College and Hospital Khyber Pakhtunkhwa. Period: April 2016 to December 2016. Material & Methods: A total of 250 extracted human maxillary first premolars were collected from the Department of Oral & Maxillofacial Surgery, Peshawar Dental College, and Hospital Khyber Pakhtunkhwa. All teeth were visually inspected to count the number of roots. Subsequently, the access cavity was prepared, and pulp extirpated from each tooth. Endodontic explorer was used to locate the canal orifice(s) at the pulp chamber floor. Later the root canal orifices were injected with India ink to stain the canals. After that roots of teeth were sectioned at different levels to note down the number of canals. Data were analyzed using SPSS version 19. The statistical significance of the variations from mean values was considered significant if the p-value was less than 0.05. Results: Out of 250 maxillary first premolar teeth, 44.8% had one root, 40.4% had two separate and 12.8% had two fused roots. Three roots were seen in 2.0% teeth. Two root canals were present in the vast majority (70.4%), whereas one and three root canals were seen in 27.6% and 2.0% teeth, respectively. The correlation between the number of roots and root canals of maxillary first premolar teeth was highly significant. Conclusions: There was a high frequency of maxillary first premolars with two roots and two root canals. [ABSTRACT FROM AUTHOR]

This is a unique case of a single-rooted maxillary premolar with two separate canals in bayonet or S-shaped radicular anatomy undergoing post-endodontic reinforcement prior to crown placement. Bayonet-shaped canals present challenges in canal negotiation, cleaning, shaping, and obturation. The complexity of these canals heightens the risk of accidental file breakage and other iatrogenic errors, posing significant challenges. Post-endodontic restoration in S-shaped canals with double curvature poses challenges in precise placement and material adaptation. A novel technique was implicated to preserve the functionality and structural aesthetics of a decayed maxillary first premolar tooth., Competing Interests: Human subjects: Consent was obtained or waived by all participants in this study. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2024, Jethi et al.)

Among the living tetrapods, mammals present a unique tooth replacement pattern, diphyodonty. Therefore, studying the dentition of mammalian ancestors is relevant to a better understanding of how this remarkable feature evolved. However, little is known about the postcanine tooth replacement pattern among Triassic cynodonts. Here, we applied the nondestructive method of microcomputed tomography (microCT) to analyze the dentition of the enigmatic Upper Triassic sectorial-toothed cynodont Charruodon tetracuspidatus (MCP 3934 PV, holotype) from the Candelaria Sequence, Santa Maria Supersequence, Brazil. The microCT-scan data allowed visualization of the replacement dentition and roots of the functional teeth, which provided information to inform interpretations of the ontogenetic stage and taxonomy of the species. A combination of dental and mandibular traits, as well as the small size of the specimen MCP 3934 PV, suggest an early ontogenetic stage. Additionally, the specimen could potentially be an ontogenetically immature form of another taxon, or a yet unknown species of probainognathian cynodont. Therefore, Charruodon tetracuspidatus is here designated as a nomen dubium, given the challenges of maintaining the species as valid., (© 2023 American Association for Anatomy.)

Protypotherium (Mammalia, Notoungulata, lnteratheriinae) is a well-known and very diverse genus of extinct native ungulates of South America, widely distributed from southern to middle latitudes of Argentina, Chile, and Bolivia. This genus exhibits distinctive species throughout the Miocene to the beginning of the Pliocene that display an interesting size pattern. The large sample of specimens studied during several years of research allows us to analyze the shape and size of upper and lower molars for nine species of Protypotherium, in order to test the hypothesis of reduction of size ranges preserving a general tooth morphology as a response to climate deterioration, documented in South America by a marked reduction of temperature that occurred during Miocene times. Elliptic Fourier analyses were used to capture the shape of the occlusal morphology and the centroid size was also retained for subsequent analyses. Our results demonstrate that: 1) a similar morphological tooth pattern is observed among all species; 2) tooth shape variation is not associated with a change in size; and 3) there is a tendency to increase the size and decrease the number of species. This striking pattern could be correlated with a global trend to lower temperatures, which indicates a deterioration of paleoenvironmental conditions. A conservative tooth pattern, together with an increase of size and a reduction in number of species were the main evolutionary and ecological tendencies accounted in Protypotherium from the early to late Miocene-beginning of the Pliocene, which were accompanied by a latitudinal displacement from Patagonia to northern areas at the end of the Miocene. [ABSTRACT FROM AUTHOR]

Proper knowledge of the anatomic structure of the root canal system is a vital prerequisite for successful root canal therapy. This report presents the endodontic management a two-rooted lower first premolar with five root canals. A similar case has not been reported to date. The use of cone beam computed tomography (CBCT) in rare and doubtful cases helps establish an accurate diagnosis and render successful endodontic treatment thereafter. This article helps broaden our knowledge about the possible anatomic diversities as to teeth with more roots and root canals than expected normally. [ABSTRACT FROM AUTHOR]

Treatment with intravenous bisphosphonate (BP) in children and adolescents with osteogenesis imperfecta (OI) started in Sweden in 1991. No human studies on the role of BP therapy in development of disturbances in tooth mineralization or tooth morphology have been published. The study cohort comprised 219 individuals who were divided into four groups: group 1, BP treatment onset before 2 years of age (n = 22); group 2, BP treatment onset between 2 and 6 years of age (n = 20); group 3, BP treatment onset between 6 and 10 years of age (n = 13); and a control group of patients with OI who had not received BP therapy (n = 164). The chi-square test was used in between-group comparisons of the prevalence of tooth agenesis. The prevalence of tooth agenesis was significantly higher in children who began BP treatment before the age of 2 years (group 1; 59%,) compared to the controls (10%; p < 0.001) and to children who had begun BP therapy between ages 2 and 6 years (group 2; 10%; p = 0.009) or between ages 6 and 10 years (group 3; 8%; p = 0.003). Different types of disturbances in the enamel formation were seen in 52 premolars, where 51 were seen in those who began BP treatment before the age of 2 years. To conclude, starting BP treatment before the age of 2 years increases the risk of abnormalities in tooth formation manifesting as morphological aberrations, tooth agenesis, and enamel defects. [ABSTRACT FROM AUTHOR]

In this study we describe a new kitefin shark (Dalatiidae) genus and species Dracipinna bracheri gen. et sp. nov. based on upper Oligocene and lower Miocene tooth fossils. The teeth were excavated at three different sites which all lie in transgression phases. The fossil shark teeth are diverse and, depending on the excavation site, indicate pelagic to mesopelagic habitats. As these fossils were not found in older or younger sediments, we suggest a patchy distribution of the species. The fossils show several dental morphological characteristics of extant Dalatiidae. Phylogenetic analyses of combined morphological and DNA sequence-based data set suggest a weakly supported sister-group relationship of D. bracheri to extant Dalatiidae. Based on the dental morphological characters, we assign the dentition to a tearing type, which is rare among squaliform sharks and only known from a single extant species with a pelagic lifestyle. [ABSTRACT FROM AUTHOR]

Objectives: Blended learning (BL) combines conventional face to face (F2F) sessions with online educational resources. This method includes the advantages of online course delivery without the omission of conventional F2F interaction. The purpose of the present study was to evaluate students' satisfaction and educational outcomes in a BL course compared to traditionally administered dental anatomy course. Methods: A prospective non‐randomized study was conducted to compare the outcomes and perception of BL for teaching dental anatomy to dental students. First year dental anatomy students (n = 98) were included (48 in the conventional F2F learning and 50 in the BL group). Multiple choice questions were used to assess the achievement of learning outcomes and the Dundee Ready Education Environment Measure (DREEM) to determine the educational environment during the course. Results: There was no significant difference in the pre‐test scores of both groups; however the mean post‐test score for the BL group (31.5 ± 4.5) was significantly higher than the F2F group (27.2 ± 4.9). The post‐test scores were comparable across both genders in the BL group while females secured significantly higher scores than males in the F2F group. The DREEM scores were also significantly higher in the BL group (147.3 ± 15.5) than the F2F group (134.5 ± 15.1) (p < 0.002). A similar pattern was observed in DREEM subscales. Conclusions: The BL course is associated with improved students' satisfaction and learner achievement compared to a conventionally administered dental anatomy course. In addition, BL enhanced students' accessibility, self‐assessment, and higher level of engagement compared to F2F delivery of the course. [ABSTRACT FROM AUTHOR]

Studies of hominin dental morphology frequently consider accessory cusps on the lower molars, in particular those on the distal margin of the tooth (C6 or distal accessory cusp) and the lingual margin of the tooth (C7 or lingual accessory cusp). They are often utilized in studies of hominin systematics, where their presence or absence is assessed at the outer enamel surface (OES). However, studies of the enamel-dentine junction (EDJ) suggest these traits may be more variable in development, morphology and position than previously thought. Building on these studies, we outline a scoring procedure for the EDJ expression of these accessory cusps that considers the relationship between these accessory cusps and the surrounding primary cusps. We apply this scoring system to a sample of Plio-Pleistocene hominin mandibular molars of Paranthropus robustus, Paranthropus boisei, Australopithecus afarensis, Australopithecus africanus, Homo sp., Homo habilis and Homo erectus from Africa and Asia (n = 132). We find that there are taxon-specific patterns in accessory cusp expression at the EDJ that are consistent with previous findings at the OES. For example, P. robustus M1s and M2s very often have a distal accessory cusp but no lingual accessory cusp, while H. habilis M1s and M2s show the opposite pattern. The EDJ also reveals a number of complicating factors; some apparent accessory cusps at the enamel surface are represented at the EDJ only by shouldering on the ridges associated with the main cusps, while other accessory cusps appear to have little or no EDJ expression at all. We also discuss the presence of double and triple accessory cusps, including the presence of a double lingual accessory cusp on the distal ridge of the metaconid in the type specimen of H. habilis (OH 7–M1) that is not clear at the OES due to occlusal wear. Overall, our observations, as well as our understanding of the developmental underpinnings of cusp patterning, suggest that we should be cautious in our comparisons of accessory cusps for taxonomic interpretations.

Dental material attributed to Palaeoloxodon huaihoensis from the Middle to Late Pleistocene were recovered over decades from the Penghu Channel during commercial fisheries activities. The National Museum of Nature Science (NMNS) has a collection of such dental material, which differs in size and morphology and likely represents ontogenetic variation and growth trajectory of various age groups of P. huaihoensis. However, little is known regarding age determination. By using length of dental material, enamel thickness (ET), and plate counts, we established the method to distinguish the age of the species, which is directly derived from the extant African forest elephant Loxodonta africana. When measuring signs of allometric growth, we found that in both the upper and lower jaws, tooth width was correlated negatively with lamellar frequency but positively with ET. In the same age group, the number of lamellae was higher in P. huaihoensis than in L. africana. The reconstructed age distribution indicated no difference in the upper or lower jaw. Notably, within our sample, P. huaihoensis is skewed towards adult and older individuals with median age between 33–34.5 years and differed significantly from that of Mammuthus primigenius in the European Kraków Spadzista site. This age distribution pattern is speculated to be related to the harsh environmental conditions and intense intraspecific competition among P. huaihoensis during the last ice age.

Studies of hominin dental morphology frequently consider accessory cusps on the lower molars, in particular those on the distal margin of the tooth (C6 or distal accessory cusp) and the lingual margin of the tooth (C7 or lingual accessory cusp). They are often utilized in studies of hominin systematics, where their presence or absence is assessed at the outer enamel surface (OES). However, studies of the enamel-dentine junction (EDJ) suggest these traits may be more variable in development, morphology and position than previously thought. Building on these studies, we outline a scoring procedure for the EDJ expression of these accessory cusps that considers the relationship between these accessory cusps and the surrounding primary cusps. We apply this scoring system to a sample of Plio-Pleistocene hominin mandibular molars of Paranthropus robustus, Paranthropus boisei, Australopithecus afarensis, Australopithecus africanus, Homo sp., Homo habilis and Homo erectus from Africa and Asia (n = 132). We find that there are taxon-specific patterns in accessory cusp expression at the EDJ that are consistent with previous findings at the OES. For example, P. robustus M1s and M2s very often have a distal accessory cusp but no lingual accessory cusp, while H. habilis M1s and M2s show the opposite pattern. The EDJ also reveals a number of complicating factors; some apparent accessory cusps at the enamel surface are represented at the EDJ only by shouldering on the ridges associated with the main cusps, while other accessory cusps appear to have little or no EDJ expression at all. We also discuss the presence of double and triple accessory cusps, including the presence of a double lingual accessory cusp on the distal ridge of the metaconid in the type specimen of H. habilis (OH 7-M1) that is not clear at the OES due to occlusal wear. Overall, our observations, as well as our understanding of the developmental underpinnings of cusp patterning, suggest that we should be cautious in our comparisons of accessory cusps for taxonomic interpretations. [ABSTRACT FROM AUTHOR]

Background: The permanent maxillary lateral incisor (PMLI) shows morphological variations, in the form of different crown shapes such as peg-shaped, cone-shaped, barrel-shaped and canine-shaped. The frequency of developmentally malformed permanent maxillary lateral incisors varies among different populations. The aim of this study was to document the frequency of different shapes of developmentally malformed permanent maxillary lateral incisors in patients visiting the three teaching dental hospitals of Peshawar. Methods: It was a cross-sectional study conducted in the Oral Diagnosis department of Peshawar Dental College, Sardar Begum Dental College, and Khyber College of Dentistry from 1st Sep 2018 to 15th June 2019. A total of 82 subjects were included that fulfilled the inclusion criteria. Shape of the malformed PMLI was determined using Computer-aided design/Computer-aided manufacturing software. Descriptive statistics including frequencies and percentages for observed developmental malformation and their types were computed and Chi-square test was applied to see the relation between various shapes and their occurrence with respect to site and position within the jaws. Results: The peg shaped PMLI was seen in 81 (98.87%) patients and barrel shaped was present in 1 (1.22%) patient. The malformed PMLIs was found to be unilateral in 38 (46.3%) and bilateral in 44 (53.7%) patients, with more common presence on both sides 44 (53.7%) followed by right side 20 (24.4%) and left side 18 (22.0%). Conclusion: The subjects having predominant developmental malformation in case of permanent maxillary lateral incisor was peg-shaped permanent maxillary lateral incisor. [ABSTRACT FROM AUTHOR]