Tooth Morphology Research Articles

Titanosaurian teeth from the South-central Pyrenees (Upper Cretaceous, Catalonia, Spain)

In Europe, the sauropod record of the uppermost Cretaceous (Campanian–Maastrichtian) concentrates in Spain, France, and Romania with up to eight titanosaurian species erected and a similar number of tooth morphotypes described. Recently, the lower Maastrichtian locality of Els Nerets from the Tremp Basin (Catalonia, Spain) has yielded the largest tooth sample for a Late Cretaceous titanosaur in the continent. A comprehensive description of 18 teeth from this locality shows that they have conical and slender crowns, pronounced development of mesial and distal carinae, a lemon-shaped cross-section, and a coarse enamel wrinkling defined by closely packed longitudinal crenulations that anastomose apically. The teeth are among the largest, slender-most, and most labiolingually compressed teeth from the region. Despite several morphological similarities with some other few titanosaur species described in other localities of SW Europe, the dental material from Els Nerets cannot be referred to any known European species. Finally, by using a rationale based on tooth morphology and wear facets distribution we propose a dental configuration of the new yet to be described taxon.

Uncovering Hidden Roots: The Fascinating Case Series of Radix Entomolaris and Radix Paramolaris in Mandibular Molars

Achieving success in endodontic treatment necessitates proper identification of the canals, thorough chemomechanical preparation, and three-dimensional obturation with an airtight seal. However, treatment failure can occur due to unpredictable tooth morphology. Although mandibular molars typically possess two roots containing three canals, the number of roots and canals may vary in certain teeth. These variations include the presence of an additional root, known as radix entomolaris (RE) if located distolingually, or radix paramolaris (RP) if located mesiobuccally. In this case series, we present six cases of mandibular first, second, and third molars with rare microstructures; one with RE and the other with RP respectively, both of which required endodontic treatment to achieve successful outcomes. Key Words: Additional third root; Anatomical variations; Endodontic treatment; Mandibular molar; Radix entomolaris; Radix paramolaris

AKT from dental epithelium to papilla promotes odontoblast differentiation

Epithelial–mesenchymal interactions occur during tooth development. The dental epithelium (DE) is regarded as the signal center that regulates tooth morphology. However, the mechanism by which DE regulates the differentiation of mesenchyme-derived dental papilla (DP) into odontoblasts remains unclear. Using miniature pigs as a model, we analyzed the expression profiles of the DE and DP during odontoblast differentiation using high-throughput RNA sequencing. The phosphatidylinositol-3-kinase (PI3K)/AKT pathway is one of the most enriched pathways in both DE and DP. The PI3K/AKT pathway was first activated in the inner enamel epithelium but not in the DP on embryonic day 50. This pathway was then activated in the odontoblast layer on embryonic day 60. We showed that AKT activation promoted odontoblast differentiation of DP cells. We further demonstrated that activation of PI3K/AKT signaling in the DE effectively increased the expression levels of AKT and dentin sialophosphoprotein in DP cells. Additionally, we found that DE cells secreted collagen type IV alpha 6 chain (COL4A6) downstream of epithelial AKT signaling to positively regulate mesenchymal AKT levels. Therefore, our data suggest that PI3K/AKT signaling from the DE to the DP promotes odontoblast differentiation via COL4A6 secretion.

RECREATING MORPHOLOGY FOR IMPROVED CLASS IV RESTORATIONS

The fractured incisor is a common occurrence in general dental practice. Achieving a positive aesthetic outcome and maximising bond strength is central to patient satisfaction and ensuring restoration longevity. Correct shade selection and the reproduction of natural anatomy in composite resin can be challenging in the anterior labial segments where the human eye’s ability to detect asymmetry plays an important role. An understanding of tooth morphology and how to replicate it will aid in this procedure. This article aims to describe a step-by-step approach towards successful morphological replication in Class IV composite resin restorations. Composite shade selection, placement techniques and polishing methods will be covered.

Applying machine learning to assess the morphology of sculpted teeth

Background/purposeProducing 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. Materials and methodsDental 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. ResultsThe 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. ConclusionThis 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.

Radiographic Identification of Dental Anomalies in Selected Telugu Population of Andhra Pradesh, India

The basic objective of any forensic examination involving unidentified human remains is to identify the individual(s). The forensic significance of teeth can be attributed to their strong resilience to explosive and thermal stress, as well as the possibly unique personal information that can be gleaned from their analysis. Furthermore, the morphology of teeth varies between (and within) populations and sexes. Anomalies in the teeth are a common component of macroscopic dental morphological differences. The current study assesses the incidence of certain dental abnormalities in Population of Andhrapradesh. This study was carried out using Pretreatment records of 630 patients of Andhra Pradesh, India. The Radiographs were reviewed for Dental Anomalies.The anomaly, number of teeth affected, and the location of Anomaly were recorded. To find correlations between dental abnormalities and gender, a Chi-square test was carried out using SPSS software. Of the 630 patients screened 427 (67.7%) presented with at least one anomaly and 203(32.3%) subjects showed no anomaly. Hypodontia is the most prevalent anomaly(38.25%) followed by Impaction(17.30%) and Rotation (17.14%). Anodontia(0.79%) and Hyperdontia(0.95%) are the least prevalent anomalies. Statistical study revealed that dental abnormalities were independent of sex. The prevalence and impact of dental anomalies in various population groups may provide important information for phylogenic and genetic studies, allowing us to comprehend intra and inter-population variation.

Characteristics of mandibular anterior alveolar bone in patients with different degrees of periodontitis: a retrospective study based on CBCT.

To investigate the alveolar bone characteristics of mandibular anterior teeth in patients with periodontitis. 100 patients with periodontitis were selected and grouped according to the degrees of alveolar bone resorption, age, gender, and tooth type. The labial thickness of the alveolar bone, the degree of alveolar bone resorption, angulation between the long axis of teeth and alveolar process, alveolar bone height and density of the mandibular anterior teeth were measured. There were significant differences in alveolar bone morphology between these three groups. Compared with the mild and moderate groups, the severe group showed that the alveolar bone in the half of the root crown was thickened, the alveolar bone height was decreased, the cancellous alveolar bone density was increased, and the cortical alveolar bone density was decreased. The resorption of alveolar bone was characterized by greater resorption of proximal bone than that of labial bone with increased bone loss. There were also differences in alveolar bone characteristics among patients of different ages, genders, and tooth types. The morphology of the mandibular anterior alveolar bone changed accordingly with the degree of periodontitis. Labial alveolar bone thickness and cortical alveolar bone density were negatively correlated with the degree of periodontitis, while alveolar bone height and cancellous alveolar bone density were positively correlated with the degree of periodontitis. These results allow clinicians to better understand the alveolar bone morphology of the mandibular anterior teeth in patients with periodontitis, facilitating better treatment design and avoiding complications.

A new gnathosaurine (Pterosauria, Archaeopterodactyloidea) from the Late Jurassic of Portugal.

An incomplete, yet remarkably-sized dentated rostrum and associated partial cervical vertebrae of a pterosaur (ML 2554) were recently discovered from the Late Jurassic (Late Kimmeridgian-Early Tithonian) Lourinhã Formation of Praia do Caniçal, of central west Portugal. This specimen exhibits features such as a spatulated anterior expansion of the rostrum, robust comb-like dentition, and pronounced rims of the tooth alveoli, indicating gnathosaurine affinities. Based on its further unique tooth and dentary morphology, a new genus and species, Lusognathus almadrava gen. et spec. nov., is proposed, making this the first named pterosaur species found within Portugal. The presence of this taxon adds yet another element to the fluvio-deltaic lagoonal environment that has been suggested as representative of the Lourinhã Formation in the Late Jurassic, further contributing to the diversity and distribution of gnathosaurines worldwide.

Deep bite -An insight

Deep bite is one of the most common malocclusion which affects children and even adults leading to a number of oral health problems. Patients with deep bite encounter periodontal and temporomandibular problems. Deep overbite refers to the increase of overlap of maxillary incisors over mandibular incisors beyond normal coverage of 30-40%. There are many factors which lead to the development of deep bite like inherent and acquired factors. Inherent factors like tooth morphology, skeletal patterns, rotation of condyle affects the bite. Acquired factors like muscle habits, loss of posterior tooth support or lateral tongue thrust may affect the bite. Deep bite can be corrected by number of different methods which include intrusion of anterior teeth, extrusion of posterior teeth or a combination of both. In non-growing patients surgical treatment is a suitable option to achieve stable results.This article describes various appliances and their biomechanics involved for correcting deepbite malocclusion

Middle mesial canal - A mystery in mandibular first molar: Report of two cases

Endodontic therapy aims at disinfection of the root canal system. Efforts are made by root canal instrumentation and chemical disinfection to remove the infected pulp tissue and debris from the root canal space. However due to variations in canal anatomy, it is impossible to instrument all the parts of canal and that may lead to persistence or progression of infection. Thorough knowledge of tooth morphology is important to improve the success rate of endodontic treatment. Missed canals are considered to be an important factor for endodontic failure and about 4% cases treated by specialists also reported have shown to have missed canals. Hence use of all the available methods to detect the additional aberrant canals and disinfection of them during root canal treatment procedure is essential for favorable endodontic outcome.

A new species of Palacrodon and a unique form of tooth attachment in reptiles

ABSTRACT Palacrodon, a near-crown stem reptile, is known from several Triassic sites across the globe, and is easily recognized by its dentition characterized by labiolingually expanded molariform teeth coupled with acrodont tooth implantation. Here we explore the nature of tooth implantation and attachment in specimens of Palacrodon from South Africa and Arizona, U.S.A. using µCT. We note the presence of unusual ridges located underneath the tooth crowns in Palacrodon browni. Such ridges are not present in specimens from Arizona, which warrants the naming of a new species P. parkeri. We conducted a broad survey of internal tooth morphology across extant and extinct pan-reptiles (n = 212), and we conclude that homologous ridges like those we observe in P. browni are not present in any other species of reptile. As such, our ability to determine the function of the ridges is limited, though we hypothesize it is related to tooth attachment via unmineralized soft tissues.

Dietary adaptations and tooth morphology in squirrels: Insights from extant and extinct species

An important part of the ecological evolution of many lineages consists of adaptations to new diets as climate and available resources changed. In this study, we inferred when squirrels adapted morphologically to new diets by analyzing data from both extant and extinct species. We relied on the relationship between tooth morphology in extant squirrels and their dietary preferences to infer the diets of extinct species. To achieve this, we employed two approaches, namely geometric morphometrics and Elliptic Fourier analyses, to measure the outline of the fourth lower premolar (p4) in occlusal view. We then used both datasets to infer the diets of extinct species. Additionally, we used phylogenetic comparative methods on extant data to explore the evolution of diet and tooth size, identifying potential drivers of squirrel morphological evolution in the context of past climatic changes. Our findings indicate that the morphology of squirrel teeth has been maintained through the evolutionary history of most lineages, but that it also has changed in some lineages as a result of adaptations to particularly demanding diets, sometimes mediated by climatic factors, which have played a crucial role in shaping tooth morphology. Furthermore, we demonstrated that both geometric morphometrics and Elliptic Fourier analyses can yield a similar percentage of correct classifications and congruent dietary inferences. This study provides valuable insights into the macroevolutionary changes in squirrels and provides further evidence of the usefulness of tooth morphology for inferring the diets of extinct mammalian species.

Three-dimensional visualization of predatory gastropod feeding teeth with synchrotron scanning.

Several families of neogastropod mollusks independently evolved the ability to drill through mineralized prey skeletons using their own mineralized feeding teeth, sometimes with shell-softening chemical agents produced by an organ in the foot. Teeth with more durable tooth shapes should extend their use and improve predator performance, but past studies have described only the cusped-side of teeth, mostly overlooking morphologies related to functional interactions between teeth. Here, we describe the three-dimensional morphology of the central drilling tooth (rachidian) from four species of the neogastropod family Muricidae using synchrotron tomographic microscopy and assemble a three-dimensional model of a multitooth series in drilling position for two of them to investigate their dynamic form. We find two new types of articulating surfaces, including a saddle joint at either end of the rachidian and a large tongue-and-groove joint in the center. The latter has a shape that maximizes contact surface area between teeth as they rotate away from each other during drilling. Articulating joints have not been described in Neogastropod radula previously, but they are consistent with an earlier hypothesis that impact forces on individual teeth during predatory drilling are dispersed by tooth-tooth interactions.

Tooth Extraction using Vertical, Conventional, and Surgical Techniques in Sebha Dental College: A Descriptive “Cross-sectional Study”

Objective: This study aimed to describe different techniques (vertical, conventional, and surgical) used in routine exodontia as well as the most teeth extracted per procedure. Methods: A descriptive cross-sectional study using data collected at the Department of Oral Maxillofacial Surgery, the Faculty of Dentistry, Sebha University, from March to December 2021, included 509 participants. The patient's age and gender, techniques of extraction, and tooth type were recorded. Results: The study included 509 participants aged 16 to 90. About 38.1% of the participants were male, and 61.9% were female. The conventional technique was the most performed (70.0%), followed by vertical (elevator) (26%), and then the surgical technique. The third molar was the most common tooth extracted by conventional technique. The vertical approach was the most successful for single and multirooted teeth. Conclusion: The result of this study suggests that the vertical extraction method may be used with a high success rate for the extraction of teeth unsuitable for conventional techniques. Therefore, the effectiveness of the exodontia technique is influenced by root morphology, position, and type of tooth.

Craniodental ecomorphology of the large Jurassic ichthyosaurian Temnodontosaurus.

Marine amniotes have played many crucial roles in ocean ecosystems since the Triassic, including predation at the highest trophic levels. One genus often placed into this guild is the large Early Jurassic neoichthyosaurian Temnodontosaurus, the only post-Triassic ichthyosaurian known with teeth which bear a distinct cutting edge or carina. This taxonomically problematic genus is currently composed of seven species which show a wide variety of skull and tooth morphologies. Here we assess the craniodental disparity in Temnodontosaurus using a series of functionally informative traits. We describe the range of tooth morphologies in the genus in detail, including the first examples of serrated carinae in ichthyosaurians. These consist of false denticles created by the interaction of enamel ridgelets with the carinal keel, as well as possible cryptic true denticles only visible using scanning electron microscopy. We also find evidence for heterodonty in the species T. platyodon, with unicarinate mesial teeth likely playing a role in prey capture and labiolingually compressed, bicarinate distal teeth likely involved in prey processing. This type of heterodonty appears to be convergent with a series of other marine amniotes including early cetaceans. Overall, the species currently referred to as the genus Temnodontosaurus show a range of craniodental configurations allowing prey to be captured and processed in different ways - for example, T. eurycephalus has a deep snout and relatively small bicarinate teeth likely specialised for increased wound infliction and grip-and-tear feeding, whereas T. platyodon has a more elongate yet robust snout and larger teeth and may be more adapted for grip-and-shear feeding. These results suggest the existence of niche partitioning at higher trophic levels in Early Jurassic ichthyosaurians and have implications for future work on the taxonomy of this wastebasket genus, as well as for research into the ecology of other extinct megapredatory marine tetrapods.

Geometric morphometrics of macro- and meiofaunal priapulid pharyngeal teeth provides a proxy for studying Cambrian “tooth taxa”

Priapulids are marine, benthic ecdysozoan worms that feed using a distinctive toothed pharynx. While only a handful of lineages have survived to the present day, the Cambrian priapulid stem group left behind a rich record of articulated body fossils and characteristic trace fossils in the form of burrows. Recently, the fossil record of isolated priapulid cuticular elements including pharyngeal teeth has gained increased attention as a means of revealing cryptic priapulid taxa otherwise unknown among macrofossils. In this study, we focus on the ecological implications of shape variation in the teeth of extant and extinct priapulids, which display substantial morphological differences between taxa and life stages. We define a landmarking scheme to capture shape variation in priapulid teeth and apply it to our dataset, which includes a breadth of tooth specimens from extant macrofaunal and meiofaunal lineages alongside numerous Cambrian priapulid teeth preserved as isolated small carbonaceous fossils. Through ordination of the principal components of shape, we explore the priapulid tooth morphospace and find evidence that its occupancy has expanded since Cambrian times, indicating a corresponding expansion of the group’s ecological niche. We also employ our geometric morphometric approach to make linear discriminant analysis-based taxon assignments based on tooth morphology, which can be helpful for classifying enigmatic “tooth taxa” known solely from fossil teeth. Finally, we use discriminant analysis to study tooth shapes from a functional perspective, considering known ecologies to characterize the ecological functions of unclassified isolated teeth.

Comparative evaluation of retention of record bases fabricated using conventional impression and modified digital scan for complete denture: An in vivo study

Background: In prosthetic dentistry, making an impression to replicate the oral health and tooth morphology is regarded as a crucial step. It is essential to ensure that the intraoral state is replicated as exactly as possible throughout this process, because any mistakes or inconsistencies could significantly impact the quality of the entire denture. In secondary impression, it’s crucial to capture the resilient oral mucosa (oral vestibule and soft palate) in order to acquire a satisfactory retention. As an alternative to conventional impression, digital scanning has been widely used in complete denture procedure. Although the digital scanning of edentulous ridges is feasible, scanning resilient oral tissues in complete denture still cannot be supported digitally. This study focuses on modifying the digital scan and comparison of retention of record bases fabricated from these modified digital scan to the record bases fabricated using conventional impression. Objectives: To compare the retention of record base prepared from conventional impression to the retention of record base from modified digital scan. Methodology: A total of 18 patients with edentulous maxillary arches will be recruited. A modified intraoral scan of the maxilla will be made on nine patients and on the remaining nine patients, a conventionally border moulded impression with a custom tray will be made. A record base with heat polymerized acrylic resin will be made on the definitive cast. Using the modified scanned image, the CAD-CAM bases will be milled. A dynamometer will be placed onto the record base; this will simulate the dislodging forces, thus clinically testing record base retention. Expected outcome: The record bases from modified digital scan will show equivalent or higher retention compared to record bases from conventional impression. Conclusions: By the end of the study, we will know whether resiliency of tissues can be recorded by modified digital scans.

A new Late Miocene Hystrix (Hystricidae, Rodentia) from Turkey.

The Çorakyerler fossil locality in Anatolia reveals unique faunal elements. This study introduces Hystrix kayae sp. nov., a new Late Miocene porcupine initially classified as Hystrix sp. Yavuz etal., 2018. This finding expands our knowledge of Late Miocene Anatolian porcupines, bringing the total number of known species to three. H. kayae sp. nov. is larger than Hystrix aryanensis and exhibits greater upper cheek tooth crown height. Its cheek tooth morphology differs from Hystrix depereti, and it possesses distinctive U-shaped choanae unlike Hystrix primigenia. The Çorakyerler locality may predate sites with H. aryanensis and H. primigenia but aligns temporally with Hystrix parvae localities. This study enhances our understanding of Late Miocene porcupine diversity in Anatolia, emphasizing the importance of Çorakyerler in unraveling the evolutionary history of these fascinating mammals.

Elemental composition and material properties of radular teeth in the heterobranch snail Gastropteron rubrum (Mollusca, Gastropoda, Cephalaspidea) foraging on hard organisms.

The molluscan feeding structure is the radula, a chitinous membrane with teeth, which are highly adapted to the food and the substrate to which the food is attached. In Polyplacophora and Patellogastropoda, the handling of hard ingesta can be facilitated by high content of chemical compounds containing Fe or Si in the tooth cusps. Other taxa, however, possess teeth that are less mineralized, even though animals have to avoid structural failure or high wear during feeding as well. Here, we investigated the gastropod Gastropteron rubrum, feeding on hard Foraminifera, diatoms and Porifera. Tooth morphologies and wear were documented by scanning electron microscopy and their mechanical properties were tested by nanoindentation. We determined that gradients of hard- and stiffness run along each tooth, decreasing from cusp to basis. We also found that inner lateral teeth were harder and stiffer than the outer ones. These findings allowed us to propose hypotheses about the radula-ingesta interaction. In search for the origins of the gradients, teeth were visualized using confocal laser scanning microscopy, to determine the degree of tanning, and analyzed with energy-dispersive X-ray spectroscopy, to test the elemental composition. We found that the mechanical gradients did not have their origins in the elemental content, as the teeth did not contain high proportions of metals or other minerals. This indicates that their origin might be the degree of tanning. However, in the tooth surfaces that interact with the ingesta high Si and Ca contents were determined, which is likely an adaptation to reduce wear.

The straight-wire appliance: Individualization versus customization.

The straight-wire appliance is an individualized, fully-programmed appliance system that has been in clinical use since the early 1970s. A study of tooth positions in individuals with naturally occurring harmonious occlusions led to the discovery of the Six Keys to Normal (Optimal) Occlusion which provided data for bracket features and prescription values incorporated into the straight-wire appliance. It was based on the notion that tooth anatomy, morphology, and optimal positions were alike enough among individuals, regardless of age, sex, or race to justify using prefabricated brackets with average prescription values. New technologies have led to advancements in appliance customization. Customized brackets can be made-to-order with one-of-a-kind prescription values and bracket base contours that fit precisely to the morphologic characteristics of the teeth. If costs and material qualities were comparable, would treatment efficiency or treatment outcomes be superior when using a customized appliance compared with a prefabricated straight-wire appliance? If not, why not?