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The Middle Pleistocene (MIS 12) human dental remains from Fontana Ranuccio (Latium) and Visogliano (Friuli-Venezia Giulia), Italy. A comparative high resolution endostructural assessment
The penecontemporaneous Middle Pleistocene sites of Fontana Ranuccio (Latium) and Visogliano (Friuli-Venezia Giulia), set c. 450 km apart in central and northeastern Italy, respectively, have yielded some among the oldest human fossil remains testifying to a peopling phase of the Italian Peninsula broadly during the glacial MIS 12, a stage associated with one among the harshest climatic conditions in the Northern hemisphere during the entire Quaternary period. Together with the large samples from Atapuerca Sima de los Huesos, Spain, and Caune de l'Arago at Tautavel, France, the remains from Fontana Ranuccio and Visogliano are among the few mid-Middle Pleistocene dental assemblages from Western Europe available for investigating the presence of an early Neanderthal signature in their inner structure. We applied two- three-dimensional techniques of virtual imaging and geometric morphometrics to the high-resolution X-ray microtomography record of the dental remains from these two Italian sites and compared the results to the evidence from a selected number of Pleistocene and extant human specimens/samples from Europe and North Africa. Depending on their preservation quality and on the degree of occlusal wear, we comparatively assessed: (i) the crown enamel and radicular dentine thickness topographic variation of a uniquely represented lower incisor; (ii) the lateral crown tissue proportions of premolars and molars; (iii) the enamel-dentine junction, and (iv) the pulp cavity morphology of all available specimens. Our analyses reveal in both samples a Neanderthal-like inner structural signal, for some aspects also resembling the condition shown by the contemporary assemblage from Atapuerca SH, and clearly distinct from the recent human figures. This study provides additional evidence indicating that an overall Neanderthal morphological dental template was preconfigured in Western Europe at least 430 to 450 ka ago.
Journal Article
Development and Evolution of Dentition Pattern and Tooth Order in the Skates And Rays (Batoidea; Chondrichthyes)
Shark and ray (elasmobranch) dentitions are well known for their multiple generations of teeth, with isolated teeth being common in the fossil record. However, how the diverse dentitions characteristic of elasmobranchs form is still poorly understood. Data on the development and maintenance of the dental patterning in this major vertebrate group will allow comparisons to other morphologically diverse taxa, including the bony fishes, in order to identify shared pattern characters for the vertebrate dentition as a whole. Data is especially lacking from the Batoidea (skates and rays), hence our objective is to compile data on embryonic and adult batoid tooth development contributing to ordering of the dentition, from cleared and stained specimens and micro-CT scans, with 3D rendered models. We selected species (adult and embryonic) spanning phylogenetically significant batoid clades, such that our observations may raise questions about relationships within the batoids, particularly with respect to current molecular-based analyses. We include developmental data from embryos of recent model organisms Leucoraja erinacea and Raja clavata to evaluate the earliest establishment of the dentition. Characters of the batoid dentition investigated include alternate addition of teeth as offset successional tooth rows (versus single separate files), presence of a symphyseal initiator region (symphyseal tooth present, or absent, but with two parasymphyseal teeth) and a restriction to tooth addition along each jaw reducing the number of tooth families, relative to addition of successor teeth within each family. Our ultimate aim is to understand the shared characters of the batoids, and whether or not these dental characters are shared more broadly within elasmobranchs, by comparing these to dentitions in shark outgroups. These developmental morphological analyses will provide a solid basis to better understand dental evolution in these important vertebrate groups as well as the general plesiomorphic vertebrate dental condition.
Journal Article
Tooth by tooth : comparing fangs, tusks, and chompers
A playful picture book that will keep readers guessing as they find out how human teeth are like and unlike those of other animals.
Book
Mobile educational tool based on augmented reality technology for tooth carving: results of a prospective cohort study
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.
Journal Article
An accurate and efficient method for occlusal tooth wear assessment using 3D digital dental models
Tooth or material wear in a dentition is a common finding that requires timely diagnosis for management and prevention of further loss or associated esthetic or functional impairment. Various qualitative and quantitative methods have been suggested to measure tooth or material wear, but they present with limitations, such as imprecision, subjectivity, or high complexity. Here we developed and assessed an efficient 3D superimposition method to accurately measure occlusal tooth wear on 3D digital dental models. For this purpose, teeth on plaster casts were manually grinded on their occlusal surfaces to simulate various degrees of tooth wear. The casts were scanned using a surface scanner. Grinded tooth crowns (T1) were segmented and compared to the original crowns (T0) using five 3D surface superimposition techniques and a gold standard technique (GS). GS measurements were obtained by using intact adjacent structures as superimposition references. The technique of choice (complete crown with 30% estimated overlap of meshes) showed the best reproducibility (maximum difference < 0.050 mm
3
) and excellent agreement with the GS technique (median difference: 0.032 mm
3
). The suggested 3D superimposition method offers a highly efficient and accurate tool for tooth wear assessment, which could be applicable to clinical conditions.
Journal Article
Wnt5a plays a crucial role in determining tooth size during murine tooth development
We have previously demonstrated that tooth size is determined by dental mesenchymal factors. Exogenous bone morphogenetic protein (BMP)4, Noggin, fibroblast growth factor (FGF)3 and FGF10 have no effect on tooth size, despite the expressions of Bmp2, Bmp4, Fgf3, Fgf10 and Lef1 in the dental mesenchyme. Among the wingless (Wnt) genes that are differentially expressed during tooth development, only Wnt5a is expressed in the dental mesenchyme. The aims of the present study were to clarify the expression pattern of Wnt5a in developing tooth germs and the role of Wnt5a in the regulation of tooth size by treatment with exogenous WNT5A with/without an apoptosis inhibitor on in vitro tooth germs combined with transplantation into kidney capsules. Wnt5a was intensely expressed in both the dental epithelium and mesenchyme during embryonic days 14–17, overlapping partly with the expressions of both Shh and Bmp4. Moreover, WNT5A retarded the development of tooth germs by markedly inducing cell death in the non-dental epithelium and mesenchyme but not widely in the dental region, where the epithelial–mesenchymal gene interactions among Wnt5a, Fgf10, Bmp4 and Shh might partly rescue the cells from death in the WNT5A-treated tooth germ. Together, these results indicate that WNT5A-induced cell death inhibited the overall development of the tooth germ, resulting in smaller teeth with blunter cusps after tooth-germ transplantation. Thus, it is suggested that Wnt5a is involved in regulating cell death in non-dental regions, while in the dental region it acts as a regulator of other genes that rescue tooth germs from cell death.
Journal Article
The efficacy of photon-initiated photoacoustic streaming in the removal of calcium silicate-based filling remnants from the root canal after rotary retreatment
The aim of the study was to evaluate the efficacy of photon-initiated photoacoustic streaming (PIPS) in the removal of filling remnants from root canals after rotary phase of retreatment and to examine the difference in the amount of residual material considering the type of sealer. Thirty-six extracted single-rooted human teeth were instrumented and randomly divided into three groups according to the filling material used: group 1: EndoSequence BC Sealer (Brassler, USA), group 2: MTA Fillapex (Angelus Solucoes Odontologicas, Londrina, Brasil), and group 3: AH Plus sealer (Dentsply DeTrey, Konstanz, Germany). Cold lateral condensation technique was used. After 2 weeks, the root canals were retreated with a rotary phase retreatment system (ProTaper Universal Retreatment, Maillefer, Ballaigues, Switzerland), followed by Er:YAG laser-activated irrigation (photon-initiated photoacoustic streaming, PIPS). The specimens were scanned in a micro-computed tomographic (micro-CT) device after root canal filling, after the rotary retreatment, and after the PIPS. There was significant reduction in the amount of filling material after the rotary phase of retreatment in all groups (
p
< 0.05), the highest in the MTA Fillapex group (
p
< 0.001) and no difference between the EndoSequence BC and the AH Plus (
p
= 0.608). There was significant reduction of the filling remnants after the PIPS in all groups (
p
< 0.05). The MTA Fillapex was the most easily removed during rotary phase of the retreatment, and there were no differences in the amount of the remaining filling material between EndoSequence BC and the AH Plus groups after rotary phase of the retreatment. The PIPS improved the removal of filling remnants in all groups.
Journal Article
Paleobiological Implications of the Ardipithecus ramidus Dentition
The Middle Awash Ardipithecus ramidus sample comprises over 145 teeth, including associated maxillary and mandibular sets. These help reveal the earliest stages of human evolution. Ar. ramidus lacks the postcanine megadontia of Australopithecus. Its molars have thinner enamel and are functionally less durable than those of Australopithecus but lack the derived Pan pattern of thin occlusal enamel associated with ripe-fruit frugivory. The Ar. ramidus dental morphology and wear pattern are consistent with a partially terrestrial, omnivorous/frugivorous niche. Analyses show that the ARA-VP-6/500 skeleton is female and that Ar. ramidus was nearly monomorphic in canine size and shape. The canine/lower third premolar complex indicates a reduction of canine size and honing capacity early in hominid evolution, possibly driven by selection targeted on the male upper canine.
Journal Article