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.

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.

Radiopacity of dental restorative materials.

OBJECTIVES: Radiopacity of dental materials enables clinician to radiographically diagnose secondary caries and marginal defects which are usually located on the proximal gingival margin. The aim of this study was to measure the radiopacity of 33 conventional resin composites, 16 flowable resin composites, and 7 glass ionomer cements and to compare the results with the radiopacity values declared by the manufacturers. MATERIALS AND METHODS: From each restorative material, six 2-mm-thick disk-shaped specimens were fabricated and eight 2-mm-thick sections of teeth were made and used as reference. The material samples and tooth sections were digitally radiographed together with the aluminum stepwedge. Gray values were obtained from the radiographic images and radiopacity values were calculated and statistically analyzed. Post hoc Tukey's honestly significant difference test was used to calculate significant differences in radiopacity values between materials and reference dentin and enamel values. RESULTS: The radiopacity values of all 56 restorative materials were above the dentin reference radiopacity value; however, 4 out of 33 conventional composites and 3 out of 16 flowable resin composites had significantly lower radiopacity than enamel (p < 0.05). There were up to 1.53 mm eq Al differences between the measured and the manufacturers' declared radiopacity values of some materials. CONCLUSIONS: Majority of the materials exceed enamel radiopacity and would not hamper radiographic diagnosis of secondary caries. However, manufacturers' data are not always reliable. CLINICAL RELEVANCE: Materials with radiopacity lower than enamel might be misinterpreted as secondary enamel caries on radiographic images, especially when applied as initial increment on the proximal gingival margin.

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.