scholarly journals Thecodont tooth attachment and replacement in bolosaurid parareptiles

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9168 ◽  
Author(s):  
Adam J. Snyder ◽  
Aaron R.H. LeBlanc ◽  
Chen Jun ◽  
Joseph J. Bevitt ◽  
Robert R. Reisz
Keyword(s):  
Alveolar Bone ◽  
Tooth Development ◽  
Tooth Replacement ◽  
Deep Roots ◽  
Pulp Cavity ◽  
Functional Tooth ◽  
Tomographic Data ◽  
Ct Data ◽  
Density Boundary ◽  
Tooth Buds

Permian bolosaurid parareptiles are well-known for having complex tooth crowns and complete tooth rows in the jaws, in contrast to the comparatively simple teeth and frequent replacement gaps in all other Paleozoic amniotes. Analysis of the specialized dentition of the bolosaurid parareptiles Bolosaurus from North America and Belebey from Russia, utilizing a combination of histological and tomographic data, reveals unusual patterns of tooth development and replacement. The data confirm that bolosaurid teeth have thecodont implantation with deep roots, the oldest known such example among amniotes, and independently evolved among much younger archosauromorphs (including dinosaurs and crocodilians) and among synapsids (including mammals). High-resolution CT scans were able to detect the density boundary between the alveolar bone and the jawbone, as confirmed by histology, and revealed the location and size of developing replacement teeth in the pulp cavity of functional teeth. Evidence provided by the paratype dentary of Belebey chengi indicates that replacement teeth are present along the whole tooth row at slightly different stages of development, with the ontogenetically more developed teeth anteriorly, suggesting that tooth replacement was highly synchronized. CT data also show tooth replacement is directly related to the presence of lingual pits in the jaw, and that migration of tooth buds occurs initially close to these resorption pits to a position immediately below the functional tooth within its pulp cavity. The size and complex shape of the replacement teeth in the holotype of Bolosaurus grandis indicate that the replacement teeth can develop within the pulp cavity to an advanced stage while the previous generation remains functional for an extended time, reminiscent of the condition seen in other amniotes with occluding dentitions, including mammals.

scholarly journals The Effects of Premature Tooth Extraction and Damage on Replacement Timing in the Green Iguana

2020 ◽  
Vol 60 (3) ◽  
pp. 581-593
Author(s):  
Kirstin S Brink ◽  
Ping Wu ◽  
Cheng-Ming Chuong ◽  
Joy M Richman
Keyword(s):  
Tooth Extraction ◽  
Tooth Development ◽  
Tooth Wear ◽  
X Rays ◽  
Tooth Replacement ◽  
Green Iguana ◽  
Dental Tissues ◽  
Functional Tooth ◽  
Green Iguanas ◽  
Replacement Cycle

Synopsis Reptiles with continuous tooth replacement, or polyphyodonty, replace their teeth in predictable, well-timed waves in alternating tooth positions around the mouth. This process is thought to occur irrespective of tooth wear or breakage. In this study, we aimed to determine if damage to teeth and premature tooth extraction affects tooth replacement timing long-term in juvenile green iguanas (Iguana iguana). First, we examined normal tooth development histologically using a BrdU pulse-chase analysis to detect label-retaining cells in replacement teeth and dental tissues. Next, we performed tooth extraction experiments for characterization of dental tissues after functional tooth (FT) extraction, including proliferation and β-Catenin expression, for up to 12 weeks. We then compared these results to a newly analyzed historical dataset of X-rays collected up to 7 months after FT damage and extraction in the green iguana. Results show that proliferation in the dental and successional lamina (SL) does not change after extraction of the FT, and proliferation occurs in the SL only when a tooth differentiates. Damage to an FT crown does not affect the timing of the tooth replacement cycle, however, complete extraction shifts the replacement cycle ahead by 4 weeks by removing the need for resorption of the FT. These results suggest that traumatic FT loss affects the timing of the replacement cycle at that one position, which may have implications for tooth replacement patterning around the entire mouth.

scholarly journals Bioengineered Tooth Buds Exhibit Features of Natural Tooth Buds

2018 ◽  
Vol 97 (10) ◽  
pp. 1144-1151 ◽  
Author(s):  
E.E. Smith ◽  
S. Angstadt ◽  
N. Monteiro ◽  
W. Zhang ◽  
A. Khademhosseini ◽  
...  
Keyword(s):  
Replacement Therapy ◽  
Tooth Development ◽  
Tooth Replacement ◽  
Dental Tissue ◽  
Bioengineered Tooth ◽  
Natural Teeth ◽  
Cell Niche ◽  
Tooth Buds ◽  
Improved Methods ◽  
Natural Tooth

Tooth loss is a significant health issue currently affecting millions of people worldwide. Artificial dental implants, the current gold standard tooth replacement therapy, do not exhibit many properties of natural teeth and can be associated with complications leading to implant failure. Here we propose bioengineered tooth buds as a superior alternative tooth replacement therapy. We describe improved methods to create highly cellularized bioengineered tooth bud constructs that formed hallmark features that resemble natural tooth buds such as the dental epithelial stem cell niche, enamel knot signaling centers, transient amplifying cells, and mineralized dental tissue formation. These constructs were composed of postnatal dental cells encapsulated within a hydrogel material that were implanted subcutaneously into immunocompromised rats. To our knowledge, this is the first report describing the use of postnatal dental cells to create bioengineered tooth buds that exhibit evidence of these features of natural tooth development. We propose future bioengineered tooth buds as a promising, clinically relevant tooth replacement therapy.

Tooth attachment, replacement, and growth in the butterfly fish, Chaetodon miliaris (Chaetodontidae, Perciformes)

1984 ◽  
Vol 62 (2) ◽  
pp. 183-189 ◽  
Author(s):  
Philip Jay Motta
Keyword(s):  
Tooth Development ◽  
Annular Ligament ◽  
Tooth Replacement ◽  
Tooth Structure ◽  
Pulp Cavity ◽  
Tooth Growth

Despite much work on tooth development and attachment in fishes there has been little published on this subject in advanced actinopterygians. This paper describes tooth structure, arrangement, attachment, growth, and replacement in the butterflyfish, Chaetodon miliaris. Each tooth is composed of a cap, shaft, and pulp cavity, and is articulated to attachment bone pedestals by an annular ligament. Tooth growth occurs initially by cap formation followed by elongation of the tooth shaft. These growing replacement teeth remain unattached to the bone, forming in troughs in the premaxilla and dentaries. Jaw tooth replacement appears to occur either laterally or lingually to functional teeth; addition of teeth lateral to functional rows may provide increase in tooth numbers during growth. The dentition and jaw morphology of this species appears to represent a compromise between planktivory and benthic feeding and may indicate a recent entry into the planktivorous guild.

Dental Development in Children After Chemotherapy

2017 ◽  
Vol 68 (6) ◽  
pp. 1397-1400
Author(s):  
Cristina Bica ◽  
Mihaela Chincesan ◽  
Daniela Esian ◽  
Krisztina Martha ◽  
Valentin Ion ◽  
...  
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
Tooth Development ◽  
Lymphoblastic Leukemia ◽  
Treatment Method ◽  
Paediatric Oncology ◽  
Structural Defects ◽  
Dental Development ◽  
Cytostatic Agents ◽  
Dental Abnormalities ◽  
Tooth Buds

Chemotherapy, as a treatment method in paediatric oncology, coincides with the physiological process of tooth development. The interference between cytostatic agents and the cycle of the cells with specialised functions in the formation and mineralisation of dental structures leads to the appearance of abnormalities in the development of the tooth buds, structural defects and disorderly eruption. We have looked into the distribution of developmental tooth disorders in a group of children suffering from malignant ailments. The study reveals a high occurrence of microdontia and agenesis of premolars among children diagnosed with high-risk acute lymphoblastic leukemia at the age between 1 and 6, as well as tooth eruption disturbances in 70% of the children. The nature and the severity of dental abnormalities depend on the type of cytostatic medication, the dosage and the frequency of therapeutic cycles, the age of the child at the beginning of the oncological therapy, as well as on the stage of the odontogenesis.

scholarly journals Histological characterization of denticulate palatal plates in an Early Permian dissorophoid

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3727 ◽  
Author(s):  
Bryan M. Gee ◽  
Yara Haridy ◽  
Robert R. Reisz
Keyword(s):  
Soft Tissue ◽  
Histological Analysis ◽  
External Morphology ◽  
Tooth Replacement ◽  
Simple Description ◽  
Pulp Cavity ◽  
Histological Data ◽  
Tissue Implantation ◽  
Soft Tissue Covering

Denticles are small, tooth-like protrusions that are commonly found on the palate of early tetrapods. Despite their widespread taxonomic occurrence and similar external morphology to marginal teeth, it has not been rigorously tested whether denticles are structurally homologous to true teeth with features such as a pulp cavity, dentine, and enamel, or if they are bony, tooth-like protrusions. Additionally, the denticles are known to occur not only on the palatal bones but also on a mosaic of small palatal plates that is thought to have covered the interpterygoid vacuities of temnospondyls through implantation in a soft tissue covering; however, these plates have never been examined beyond a simple description of their position and external morphology. Accordingly, we performed a histological analysis of these denticulate palatal plates in a dissorophoid temnospondyl in order to characterize their microanatomy and histology. The dentition on these palatal plates has been found to be homologous with true teeth on the basis of both external morphology and histological data through the identification of features such as enamel and a pulp cavity surrounded by dentine. In addition, patterns of tooth replacement and ankylosis support the hypothesis of structural homology between these tiny teeth on the palatal plates and the much larger marginal dentition. We also provide the first histological characterization of the palatal plates, including documentation of abundant Sharpey’s fibres that provide a direct line of evidence to support the hypothesis of soft tissue implantation. Finally, we conducted a survey of the literature to determine the taxonomic distribution of these plates within Temnospondyli, providing a broader context for the presence of palatal plates and illustrating the importance of maintaining consistency in nomenclature.

scholarly journals The Role of Discoidin Domain Receptor 2 in Tooth Development

2019 ◽  
Vol 99 (2) ◽  
pp. 214-222
Author(s):  
F.F. Mohamed ◽  
C. Ge ◽  
A. Binrayes ◽  
R.T. Franceschi
Keyword(s):  
Expression Pattern ◽  
Alveolar Bone ◽  
Tooth Development ◽  
Tyrosine Kinase Receptor ◽  
Loss Of Function ◽  
Wild Type ◽  
Specific Expression ◽  
Tooth Formation ◽  
Discoidin Domain Receptor ◽  
Discoidin Domain Receptor 2

Collagen signaling is critical for proper bone and tooth formation. Discoidin domain receptor 2 (DDR2) is a collagen-activated tyrosine kinase receptor shown to be essential for skeletal development. Patients with loss of function mutations in DDR2 develop spondylo-meta-epiphyseal dysplasia (SMED), a rare, autosomal recessive disorder characterized by short stature, short limbs, and craniofacial anomalies. A similar phenotype was observed in Ddr2-deficient mice, which exhibit dwarfism and defective bone formation in the axial, appendicular, and cranial skeletons. However, it is not known if Ddr2 has a role in tooth formation. We first defined the expression pattern of Ddr2 during tooth formation using Ddr2-LacZ knock-in mice. Ddr2 expression was detected in the dental follicle/sac and dental papilla mesenchyme of developing teeth and in odontoblasts and the periodontal ligament (PDL) of adults. No LacZ staining was detected in wild-type littermates. This Ddr2 expression pattern suggests a potential role in the tooth and surrounding periodontium. To uncover the function of Ddr2, we used Ddr2 slie/slie mice, which contain a spontaneous 150-kb deletion in the Ddr2 locus to produce an effective null. In comparison with wild-type littermates, Ddr2 slie/slie mice displayed disproportional tooth size (decreased root/crown ratio), delayed tooth root development, widened PDL space, and interradicular alveolar bone defects. Ddr2 slie/slie mice also had abnormal collagen content associated with upregulation of periostin levels within the PDL. The delayed root formation and periodontal abnormalities may be related to defects in RUNX2-dependent differentiation of odontoblasts and osteoblasts; RUNX2-S319-P was reduced in PDLs from Ddr2 slie/slie mice, and deletion of Ddr2 in primary cell cultures from dental pulp and PDL inhibited differentiation of cells to odontoblasts or osteoblasts, respectively. Together, our studies demonstrate odontoblast- and PDL-specific expression of Ddr2 in mature and immature teeth, as well as indicate that DDR2 signaling is important for normal tooth formation and maintenance of the surrounding periodontium.

scholarly journals A machine learning based approach to the segmentation of micro CT data in archaeological and evolutionary sciences

2019 ◽  
Author(s):  
Thomas O’Mahoney ◽  
Lidija Mcknight ◽  
Tristan Lowe ◽  
Maria Mednikova ◽  
Jacob Dunn
Keyword(s):  
Machine Learning ◽  
High Resolution ◽  
Leading Edge ◽  
Micro Ct ◽  
Robust Method ◽  
Tomographic Data ◽  
Ct Data

AbstractSegmentation of high-resolution tomographic data is often an extremely time-consuming task and until recently, has usually relied upon researchers manually selecting materials of interest slice by slice. With the exponential rise in datasets being acquired, this is clearly not a sustainable workflow. In this paper, we apply the Trainable Weka Segmentation (a freely available plugin for the multiplatform program ImageJ) to typical datasets found in archaeological and evolutionary sciences. We demonstrate that Trainable Weka Segmentation can provide a fast and robust method for segmentation and is as effective as other leading-edge machine learning segmentation techniques.

scholarly journals Synodontia between Permanent Mandibular Central & Lateral Incisors

2015 ◽  
Vol 5 (2) ◽  
pp. 70-72
Author(s):  
Nitin Agarwal ◽  
Debanti Giri ◽  
Saurabh Mathur ◽  
Kirti Agarwal
Keyword(s):  
Primary Teeth ◽  
Tooth Development ◽  
Permanent Tooth ◽  
Developmental Anomaly ◽  
Permanent Teeth ◽  
Anterior Teeth ◽  
Incisal Edge ◽  
Fused Teeth ◽  
Research And Education ◽  
Tooth Buds

Dental fusion also called ‘synodontia’ is a rare dental developmental anomaly in which the union of two independently developing primary or permanent tooth buds occurs. Tooth fusion is defined as union between the dentin and / or enamel of two or more separate developing teeth. The fusion may be partial or total depending upon the stage of tooth development at the time of union. The etiology of fusion is still unclear. The overall prevalence of the tooth fusion is approximately 0.5%. Fusion may be unilateral or bilateral and most often occurs in primary teeth with more predilections for anterior teeth. Clinically fused anterior teeth frequently have a groove or notch on the incisal edge that goes in buccolingual direction and radiographically, the dentin of fused teeth always appears to be joined in some region with separate pulp chambers and canals. Hence the cases of fusion of permanent teeth in different ages are presented.Bangladesh Journal of Dental Research and Education Vol.5(2) 2015: 70-72

Review of the Indian Ocean spikefish genus Mephisto (Tetraodontiformes: Triacanthodidae)

Zootaxa ◽  
2020 ◽  
Vol 4802 (1) ◽  
pp. 82-98
Author(s):  
KATHERINE E. BEMIS ◽  
JAMES C. TYLER ◽  
PETER N. PSOMADAKIS ◽  
LAUREN NEWELL FERRIS ◽  
APPUKUTTANNAIR BIJU KUMAR
Keyword(s):  
Indian Ocean ◽  
Bay Of Bengal ◽  
East Coast ◽  
Andaman Sea ◽  
Micro Ct ◽  
Tooth Replacement ◽  
Color Photograph ◽  
Replacement Pattern ◽  
The Indian Ocean ◽  
Ct Data

We redescribe the triacanthodid spikefish Mephisto fraserbrunneri Tyler 1966 based upon eight specimens (five newly reported herein) and the first color photographs of freshly collected specimens; these data are compared with that of the single specimen of the recently described M. albomaculosus Matsuura, Psomadakis, and Mya Than Tun 2018. Both species are found in the Indian Ocean, with M. fraserbrunneri known from the Arabian Sea off the east coast of Africa to the eastern Bay of Bengal, and M. albomaculosus confirmed only from the type locality in the Andaman Sea (a color photograph of an individual M. cf. albomaculosus from the Bay of Bengal that was not retained is also presented). We describe and diagnose the genus Mephisto and provide a key to the two species based upon all available specimens. We also provide a distribution map for both species and summarize literature records. Using micro-CT data, we show that Mephisto fraserbrunneri replaces teeth intraosseously, which suggests this tooth replacement pattern is plesiomorphic for Tetraodontiformes. 

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