Radix entomolaris and radix paramolaris: A cone-beam computed tomography study of permanent mandibular molars in a large sample from Slovenia

OBJECTIVES

To investigate the prevalence, unilateral/bilateral concurrency, and external morphology of permanent mandibular molars (PMMs) with radix entomolaris (RE) and radix paramolaris (RP) in a sample from Slovenia.

DESIGN

Medium field-of-view cone-beam computed tomography images of 1315 participants (681 males, 634 females) aged 13-90 years (mean age 45.5) were retrospectively examined. A total of 1363 first, 1824 second, and 1314 third PMMs were evaluated. The external morphology of the affected teeth was categorized according to Carlsen and Alexandersen's classifications.

RESULTS

The individual-level RE frequencies in the first, second, and third PMMs were 1.6%, 1.9%, and 10.1%, respectively. The respective RP frequencies were 0%, 1.8%, and 3.2%. The first PMMs exclusively exhibited type A RE morphology, whereas in the second and third PMMs, types B and AC morphologies predominated. Bilateral concurrence rates were low (0-7.1%), with the exception of type A RE in first PMMs (62.5%). RE occurrences in the first and second PMMs were correlated (odds ratio = 70.2; 95% confidence interval 17.4 -282.7; P < 0.001). In concurrent cases, the second PMM followed its anterior neighbor in expressing type A morphology, and conversely, all affected second PMMs standing next to a two-rooted first PMM exhibited non-type A morphology.

CONCLUSIONS

In this sample, the first and second PMMs exhibited low supernumerary root frequencies comparable to those of other European samples. The third PMM was most often affected. The presence of RE on the first PMM increased the possibility of its presence on the adjacent second PMM and vice versa.

Dental ancestry estimation in a 1500 years old human skeleton from Slovenia using a new web-based application rASUDAS

The present study was performed on a skeleton excavated from the Late Roman Period necropolis in Ptuj, Eastern Slovenia. Previous anthropological analysis has revealed that the skeleton belongs to a male, who died in his early twenties; however, determination of ancestry was problematic. The skull displays artificial cranial deformation of circular fronto-occipital type and shows some Asiatic anthroposcopic features. However, the inter-orbital projection method of Gill and Hughes has placed him into the Western Eurasian group. The aim of the present investigation was to estimate whether this individual belonged to Western Eurasian or Eastern Asian ancestry group by analyzing his dental morphology. Twenty-one key dental traits for ancestry assessment were scored following the Arizona State University Dental Anthropology System (ASUDAS). Morphology of the roots was scored from cone-beam computed tomography (CBCT) images of the dentition. These scores were input into a web application rASUDAS (beta version) which uses a naive Bayes classifier algorithm to assign an individual to a preselected number (from two to seven) of ancestry groups. The analysis revealed a complex tooth crown morphology (moderate maxillary incisor shoveling, 5-cusped maxillary first and second molars, 6-cusped mandibular first molars, 5-cusped mandibular second molars, multiple molar enamel extensions) and a simplified external root morphology (27 single-rooted teeth out of 32). Both mandibular second molars and the right mandibular third molar possess a C-shaped root canal. In addition, the mandible bilaterally exhibits accessory mental foramina. In a two-group analysis, the application calculated that the probability of assigning the individual from Ptuj to Eastern Asian ancestry group was close to 1.0. The result is in agreement with archaeological evidence which has indicated that this individual was a Hun warrior from the Migration Period of Europe. This study demonstrates a modern approach to estimating ancestry from dental morphology in bioarcheological and forensic contexts.

On the appendicular anatomy of the xiphosurid Tachypleus syriacus and the evolution of fossil horseshoe crab appendages

Xiphosurida-crown group horseshoe crabs-are a group of morphologically conservative marine chelicerates (at least since the Jurassic). They represent an idealised example of evolutionary stasis. Unfortunately, body fossils of horseshoe crabs seldom preserve appendages and their associated features; thus, an important aspect of their morphology is absent in explorations of their conservative Bauplan. As such, fossil horseshoe crab appendages are rarely considered within a comparative framework: previous comparisons have focussed almost exclusively on extant taxa to the exclusion of extinct taxa. Here, we examine eight specimens of the xiphosurid Tachypleus syriacus (Woodward, 1879) from the Cenomanian (ca 100 Ma) Konservat-Lagerstätten of Lebanon, five of which preserve the cephalothoracic and thoracetronic appendages in exceptional detail. Comparing these appendages of T. syriacus with other fossil xiphosurids highlights the conserved nature of appendage construction across Xiphosurida, including examples of Austrolimulidae, Paleolimulidae, and Limulidae. Conversely, Belinuridae have more elongate cephalothoracic appendages relative to body length. Differences in appendage sizes are likely related to the freshwater and possible subaerial life modes of belinurids, contrasting with the primarily marine habits of other families. The morphological similarity of T. syriacus to extant members of the genus indicates that the conserved nature of the generic lineage can be extended to ecological adaptations, notably burrowing, swimming, possible diet, and sexual dimorphism.

The role of clinical examination in the detection of permanent maxillary molars with two palatal roots

BACKGROUND

The aim of the study was to determine whether the presence of two palatal roots (2PR) in permanent maxillary molars (PMMs) could be predicted by observing dental morphological traits during the clinical examination.

MATERIALS AND METHODS

A total of 18 second and 26 third PMMs with 2PR were examined from the collection of extracted teeth. The reference sample of 44 extracted PMMs with one palatal root was selected such that pairs of morphologically matching PMMs with one and 2PR were formed. The external morphology of these tooth pairs was examined under a stereomicroscope and distinguishing traits were registered. The Fisher's exact test was applied to examine differences between second and third PMMs. Additionally, the external morphology of 17 PMM with 2PR in 15 patients was analysed retrospectively.

RESULTS

Extracted PMMs with 2PR possessed the following distinguishing morphological traits: crown wider on the palatal half (55.3%), double Carabelli cusps (23.7%), pronounced palatal indentation of the crown (20.5%), thick palatal enamel extension (16.3%), palato-radicular groove (11.6%) and palatal enamel pearl (2.3%). Differences between second and third PMMs were not statistically significant (p > 0.05). At least one distinguishing trait was present in 63.4% and 94.1% of extracted and clinically evaluated PMMs with 2PR, respectively. Omega-shaped deformation of the dental arch may be the first clinically observable clue to this root constellation.

CONCLUSIONS

Clinical examination of tooth morphology and shape of the dental arch is essential for the detection PMMs with 2PR.

Painful neuropathy caused by compression of the inferior alveolar nerve by focal osteosclerotic lesion of the mandible: A case report

Osteosclerotic lesions are a common finding on dental radiographs. They are considered developmental variants of a normal bone architecture and they usually do not need any treatment. The purpose of this article is to present a rare case of osteosclerotic lesion of the mandible causing trigeminal neuropathy by compression of the alveolar nerve. The pain started with dental hypersensitivity of the mandibular right first molar. Later on, signs of irreversible molar tooth pulpitis developed. Endodontic therapy and apicoectomy did not resolve the pain, which later intensified, and painful neuropathy localized to inferior alveolar nerve developed; therefore, surgical decompression was indicated. Treating a dental patient with neuralgic pain is always a challenge, especially if there is no obvious source or reason for this type of pain. A clear evaluation and treatment protocol are important to minimize the patient's morbidity and avoid unnecessary overtreatment.

Triassic actinopterygian fishes: the recovery after the end-Permian crisis

In the last 15 years, the discovery of several new actinopterygian fish faunas from the Early and Middle Triassic of the Tethys, cast new light on the timing, speed and range of their recovery after the end-Permian crisis. In addition to several new taxa having been described, the stratigraphical and geographical record of many others have been greatly extended. In fact, most of the new fossiliferous sites are in southern China, thus at the Eastern end of the Tethys, and furthermore a few are somewhat older (Chaohu, Panxian, Luoping) than the major classical Western Tethys sites (Monte San Giorgio). Following these new finds, it is possible to have a better definition of the Triassic recovery stages. Indeed, after a quite short phase till the end of the Smithian (Olenekian, Early Triassic) in which a rather consistent fauna was present all around the Pangea coasts, a major radiation occurred in the Early-Middle Anisian after the new Middle Triassic fish fauna already appeared in the late Early Triassic, thus occuring well before what was previously supposed from the Alps localities. Furthermore, the new assemblages from southern China point to an early broader differentiation among the basal neopterygians rather than in the 'subholosteans', the group that was then dominant in the Western Tethys since the Late Anisian. It stands that during the Norian a new basal neopterygian radiation gave rise to several new branches that dominated the remaining part of the Mesozoic.

Effect of dental material fluorescence on DIAGNOdent readings

OBJECTIVE

Diagnosis of secondary caries with the DIAGNOdent device has been found to be comparable to visual and radiographic diagnostic methods, but the fluorescence of restorative materials might affect DIAGNOdent values and result in false-positive diagnosis. The aims of this study were: (1) to measure baseline fluorescence of restorative materials and fluorescence changes induced by aging, bleaching, staining, and polishing; (2) to assess intra-examiner reproducibility of these measurements; and (3) to compare the values obtained with the DIAGNOdent against the threshold values for enamel and dentinal caries.

MATERIAL AND METHODS

270 disk-shaped specimens fabricated from 15 different restorative materials were divided into 3 groups, which were aged in water, bleached with 10% carbamide peroxide, and stained with red wine. Specimen fluorescence was measured with the DIAGNOdent before and after these treatments. The red-wine-stained specimens were also polished and measured again.

RESULTS

Intra-examiner reproducibility of the measurements was excellent. For all materials, baseline DIAGNOdent values, as well as the values of aged and bleached samples, were considerably lower than the dentinal caries threshold. The values of one stained filled resin fissure sealant, one stained resin composite, and one stained resin-modified glass ionomer exceeded the dentinal caries threshold. Polishing reduced these DIAGNOdent values to below the dentinal caries threshold, except for the filled resin fissure sealant specimen.

CONCLUSIONS

Stained dental materials might affect DIAGNOdent readings and consequently result in false-positive diagnoses of secondary caries. Dental fillings should be polished prior to DIAGNOdent measurement.