scholarly journals Dental ontogeny and replacement in Pliosauridae

2015 ◽  
Vol 2 (11) ◽  
pp. 150384 ◽  
Author(s):  
Judyth Sassoon ◽  
Davide Foffa ◽  
Ryan Marek
Keyword(s):  
Tooth Development ◽  
Medial Axis ◽  
Tooth Eruption ◽  
Dental Morphology ◽  
Tooth Replacement ◽  
Posterior Teeth ◽  
Anterior Teeth ◽  
Dental Ontogeny ◽  
Replacement Cycle

Dental morphology and patterns of tooth replacement in representatives of the clade Pliosauridae (Reptilia, Sauropterygia) are evaluated in detail. The jaws of one basal ( Thalassiodracon hawkinsii ) and two derived species ( Pliosaurus carpenteri , Pliosaurus kevani ) were visualized by μCT scans, and the ontogenetic patterns, or ‘movement paths’, of replacement teeth could be mapped. Other specimens ( Peloneustes philarchus and Pliosaurus westbuyensis ) with well-preserved jaws containing functional and replacement teeth in situ were also examined directly, and waves of tooth replacement could be inferred from the degree of in situ tooth development and the fusion between functional and replacement alveoli. The analysis revealed symmetrical tooth eruption over the medial axis throughout the length of the jaw in the basal pliosaurid Thalassiodracon . By contrast, symmetrical tooth eruption patterns occur only along the anterior sections of the jaws of derived pliosaurids. In Pliosaurus , replacement schedules differ in the anterior and posterior portions of the jaws and appear to correlate with differences in tooth morphology and symmetrical replacement. The anterior teeth exhibit longer replacement cycle periods and symmetrical replacement, while shorter cycle periods and asymmetry are seen posteriorly. A longer period suggests slower replacement and is characteristic of large, specialized caniniform teeth in the longer snouted Late Jurassic taxa. Smaller posterior teeth have a shorter period and therefore a faster replacement cycle. The transition from long to short replacement period over the length of the jaw is thought to account for the loss of symmetry. This differentiation could relate to differential tooth function and a type of heterodonty. We therefore propose a new model of pliosaurid tooth replacement patterns and present it in a phylogenetic context.

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 Quantification of the Dental Morphology of Orangutans

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
P. Nambiar ◽  
J. John ◽  
Samah M. Al-Amery ◽  
K. Purmal ◽  
W. L. Chai ◽  
...  
Keyword(s):  
Root Canal ◽  
Dental Treatment ◽  
Dental Morphology ◽  
Crown Height ◽  
Posterior Teeth ◽  
Crown Length ◽  
Bornean Orangutan ◽  
Anterior Teeth ◽  
Root Canal Morphology ◽  
Canal Morphology

Orangutans are believed to have close biological affinities to humans. Teeth being the hardest tissue provide useful information on primate evolution. Furthermore, knowledge of the pulp chamber and root canal morphology is important for dental treatment. A female Bornean orangutan and a Sumatran male orangutan skull were available for this study. Both of their dentitions, comprising 50 teeth, were scanned employing the cone-beam computed tomography for both metrical and nonmetrical analyses. Measurements included tooth and crown length, root length, enamel covered crown height, root canal length (posterior teeth), length of pulpal space (anterior teeth), and root canal width. Nonmetrical parameters included number of canals per root, number of foramina in each root, and root canal morphology according to Vertucci’s classification. It was found that the enamel covered crown height was the longest in the upper central incisors although the canine was the longest amongst the anterior teeth. Both the upper premolars were three-rooted while the lower second premolar of the Sumatran orangutan was two-rooted, with two foramina. The mandibular lateral incisors of the Bornean orangutan were longer than the central incisors, a feature similar to humans. In addition, secondary dentine deposition was noticed, a feature consistent with aged humans.

scholarly journals An enigmatic lower jaw from the Lower Muschelkalk (Anisian, Middle Triassic) of Winterswijk provides insights into dental configuration, tooth replacement and histology

2021 ◽  
Vol 100 ◽  
Author(s):  
Stephan N.F. Spiekman ◽  
Nicole Klein
Keyword(s):  
Middle Triassic ◽  
Posterior Part ◽  
Dorsal Surface ◽  
Dental Morphology ◽  
Posterior Teeth ◽  
Dental Lamina ◽  
Computed Tomographic ◽  
Anterior Teeth ◽  
Replacement Pattern ◽  
Lower Muschelkalk

Abstract In the aftermath of the Permo-Triassic mass extinction event, several reptile lineages radiated to form major components of marine faunas during the entire Mesozoic. The Lower Muschelkalk, which was deposited within a shallow inland sea in the Germanic Basin during the Middle Triassic, is one of the most important regions for understanding the early evolution of Mesozoic marine reptiles. Here, we present a new specimen from the Lower Muschelkalk of Winterswijk in the Netherlands, comprising an isolated left dentary that is morphologically distinct from any well-known Triassic vertebrate. We provide a detailed description of the jaw and the teeth using histological and micro-computed tomographic analyses. The anterior teeth are fang-like and curved, whereas the posterior teeth are wider and triangular-shaped. Tooth implantation is thecodont and teeth are ankylosed to the base of the alveolus. Replacement teeth are developed directly lingual to the functional teeth, starting with the formation of a resorption cavity on the dorsal surface of the alveolar margin. The replacement pattern cannot be observed in detail but is regular in the posterior part of the dentary with each tooth being alternated with an empty alveolus. The specimen can likely be assigned to Eosauropterygia based on its jaw morphology and dental morphology and replacement pattern, and it is remarkably similar to maxillae referred to the enigmatic Lamprosauroides goepperti from the Lower Muschelkalk of Poland. The dentary from Winterswijk lacks enlarged, ‘alveolarised’ crypts and corresponding distinct dental lamina foramina (DLFs) for the replacement teeth, a configuration that is typical of Sauropterygia, but which was likely not omnipresent in this clade. The specimen also exhibits loosely folded plicidentine at the roots of the teeth, likely representing the first identification of this feature in Sauropterygia.

Unusual Dental Morphology in a Chimpanzee: A Case Report Utilizing Cone-Beam Computed Tomography

2018 ◽  
Vol 35 (2) ◽  
pp. 96-102 ◽  
Author(s):  
Samah M. Al-Amery ◽  
Phrabhakaran Nambiar ◽  
Jacob John ◽  
Kathiravan Purmal ◽  
Wei Cheong Ngeow ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Case Report ◽  
Cone Beam Computed Tomography ◽  
Anatomical Variations ◽  
Cone Beam ◽  
Dental Morphology ◽  
Posterior Teeth ◽  
Pulp Cavity ◽  
Anterior Teeth ◽  
Dens Invaginatus

This case report illustrates the teeth morphology of a chimpanzee and its anatomical variations. A well-preserved skull of a male Pan troglodytes troglodyte chimpanzee was scanned using a cone-beam computed tomography machine. Measurements included tooth and crown height, root length, root canal length and width (posterior teeth), and pulp cavity length (anterior teeth). Nonmetrical parameters included number of canals and foramina per root of every root. Interestingly, the mandibular central incisor was longer than the lateral incisor, and all the mandibular anterior teeth presented with a solitary flame-shaped or conical-calcified structure in their pulp cavity. The premolars are usually dual rooted except for the first maxillary premolar that displayed 3 roots. Other unusual discoveries were the presence of bilateral radicular dens invaginatus in the mandibular first premolars and the possibility of having 2 canals and 2 foramina in the roots of the posterior teeth. The presence of conical stone mineralizations at the pulp cavity and the presence of dens invaginatus were of particular interest.

scholarly journals Comparison of the accuracy of intraoral scans between complete-arch scan and quadrant scan

2020 ◽  
Vol 21 (1) ◽  
Author(s):  
Youn-Gyeong Moon ◽  
Kyung-Min Lee
Keyword(s):  
Third Molar ◽  
Careful Consideration ◽  
Missing Teeth ◽  
Posterior Teeth ◽  
Anterior Teeth ◽  
Posterior Quadrant ◽  
Left Posterior ◽  
The Right ◽  
Best Fit ◽  
Posterior Area

Abstract Objective To compare the accuracy of complete-arch scans and quadrant scans obtained using a direct chairside intraoral scanner. Material and methods Intraoral scans were obtained from 20 adults without missing teeth except for the third molar. Maxillary and mandibular complete-arch scans were carried out, and 4 quadrant scans for each arch were performed to obtain right posterior, right anterior, left anterior, and left posterior quadrant scans. Complete-arch scans and quadrant scans were compared with corresponding model scans using best-fit surface-based registration. Shell/shell deviations were computed for complete-arch scans and quadrant scans and compared between the complete-arch scans and each quadrant scans. In addition, shell/shell deviations were calculated also for each individual tooth in complete-arch scans to evaluate factors which influence the accuracy of intraoral scans. Results Complete-arch scans showed relatively greater errors (0.09 ~ 0.10 mm) when compared to quadrant scans (0.05 ~ 0.06 mm). The errors were greater in the maxillary scans than in the mandibular scans. The evaluation of errors for each tooth showed that the errors were greater in posterior teeth than in anterior teeth. Comparing the right and left errors, the right side posterior teeth showed a more substantial variance than the left side in the mandibular scans. Conclusion The scanning accuracy has a difference between complete-arch scanning and quadrant scanning, particularly in the posterior teeth. Careful consideration is needed to avoid scanning inaccuracy for maxillary or mandibular complete-arch, particularly in the posterior area because a complete-arch scan might have potential error than a quadrant scan.

scholarly journals Dual-section versus conventional archwire for en-masse retraction of anterior teeth with direct skeletal anchorage: a finite element analysis

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Ryo Hamanaka ◽  
Daniele Cantarella ◽  
Luca Lombardo ◽  
Lorena Karanxha ◽  
Massimo Del Fabbro ◽  
...  
Keyword(s):  
Finite Element ◽  
Tooth Movement ◽  
Occlusal Plane ◽  
Skeletal Anchorage ◽  
Element Analysis ◽  
Posterior Teeth ◽  
Posterior Portion ◽  
Anterior Teeth ◽  
Retraction Force ◽  
En Masse Retraction

Abstract Background The aim of this study is to compare the biomechanical effects of the conventional 0.019 × 0.025-in stainless steel archwire with the dual-section archwire when en-masse retraction is performed with sliding mechanics and skeletal anchorage. Methods Models of maxillary dentition equipped with the 0.019 × 0.025-in archwire and the dual-section archwire, whose anterior portion is 0.021 × 0.025-in and posterior portion is 0.018 × 0.025-in were constructed. Then, long-term tooth movement during en-masse retraction was simulated using the finite element method. Power arms of 8, 10, 12 and 14 mm length were employed to control anterior torque, and retraction forces of 2 N were applied with a direct skeletal anchorage. Results For achieving bodily movement of the incisors, power arms longer than 14 mm were required for the 0.019 × 0.025-in archwire, while between 8 and 10 mm for the dual-section archwire. The longer the power arms, the greater the counter-clockwise rotation of the occlusal plane was produced. Frictional resistance generated between the archwire and brackets and tubes on the posterior teeth was smaller than 5% of the retraction force of 2 N. Conclusions The use of dual-section archwire might bring some biomechanical advantages as it allows to apply retraction force at a considerable lower height, and with a reduced occlusal plane rotation, compared to the conventional archwire. Clinical studies are needed to confirm the present results.

Cranial and dental morphology in a bohaiornithid enantiornithine with information on its tooth replacement pattern

2021 ◽  
pp. 105021
Author(s):  
Di Liu ◽  
L.M. Chiappe ◽  
Becky Wu ◽  
Qingjin Meng ◽  
Yuguang Zhang ◽  
...  
Keyword(s):  
Dental Morphology ◽  
Tooth Replacement ◽  
Replacement Pattern

Full-Mouth Rehabilitation for a Patient With Dentinogenesis Imperfecta: A Clinical Report

2014 ◽  
Vol 40 (5) ◽  
pp. 593-600 ◽  
Author(s):  
Sompop Bencharit ◽  
Michael B. Border ◽  
C. Russell Mack ◽  
Warren C. Byrd ◽  
John T. Wright
Keyword(s):  
Dental Implants ◽  
Computer Aided Design ◽  
Genetic Disorder ◽  
Asian Woman ◽  
Clinical Report ◽  
Dentinogenesis Imperfecta ◽  
Posterior Teeth ◽  
Anterior Teeth ◽  
Computer Aided ◽  
Full Mouth Rehabilitation

Dentinogenesis imperfecta (DI) is a genetic disorder affecting the structural integrity of the dentin that can result in weakened dentin. The affected teeth, especially posterior teeth, often need to be extracted due to severe wear or fracture. This frequently yields a loss of posterior occlusion and occlusal vertical dimension. Besides wear and fracture, anterior teeth often have an unesthetic appearance because of discoloration. Current treatments of choice, including composite bonding restorations and, more recently, all-ceramic restorations, are typically suggested to preserve the remaining teeth and tooth structure. However, there are a limited number of studies on dental implants in patients with DI. The effectiveness of dentin bonding and dental implants in patients with DI is not known. This clinical report describes a 32-year-old Asian woman with DI who underwent full-mouth rehabilitation. The posterior occlusion, mostly in the molar areas, was restored with dental implants and ceramometal restorations. The anterior teeth and premolars were restored with bonded lithium disilicate glass-ceramic pressed veneers and crowns made with computer-aided design/computer-aided manufacturing. This case demonstrates that restoring functional occlusion and esthetics for a patient with DI can be completed successfully using contemporary implant therapy and adhesive dentistry.

scholarly journals The quality of etched enamel in different regions and tooth types and its significance in bonding and the development of white spot lesions

2021 ◽  
Author(s):  
Elisabeth C. Barnhart ◽  
Phillip M. Campbell ◽  
Amal Noureldin ◽  
Katie Julien ◽  
Peter H. Buschang
Keyword(s):  
White Spot ◽  
Cervical Region ◽  
White Spot Lesions ◽  
Micro Computed Tomography ◽  
Human Teeth ◽  
Posterior Teeth ◽  
Material Density ◽  
Anterior Teeth ◽  
Before And After

ABSTRACT Objectives To quantify differences in the etch quality of enamel within and between human teeth, which has not previously been attempted. Materials and Methods The buccal right and left halves of 27 extracted human teeth were randomly allocated to scanning electron microscopy (SEM) or micro–computed tomography (μCT) for evaluation. The buccal surfaces were pumiced, etched with 37% phosphoric acid gel etchant for 15 seconds, rinsed, and air dried. Each tooth was divided into three regions (incisal, middle, and cervical) and viewed after etching at 1200× magnification with SEM. The μCT scans were taken before and after etching to calculate apparent and material mineral densities. Results SEM showed greater aprismatic enamel and poorer etch quality (ie, significantly less percentage enamel) for the posterior than anterior teeth and for the cervical region than for the incisal and middle regions of all teeth. Although there were no density differences prior to etching, μCT demonstrated that etching increased material density significantly more for the anterior than posterior teeth. Prior to etching, the enamel in the cervical regions was significantly less dense than the enamel in the middle or incisal regions. Etching significantly increased the material density of all three regions, which decreased initial regional differences. After etching, the apparent density of the cervical region remained significantly lower than the densities of the other two regions. Conclusions Based on SEM and μCT, there is greater aprismatic enamel and inferior etch quality in the cervical regions of all tooth types and is clinically significant in explaining the failure of sealant retention and the propensity for white spot lesions.

scholarly journals Effectiveness of the Greater Palatine Nerve Block for Anaesthetising Anterior Palate: A Prospective Study

2020 ◽  
Author(s):  
Gopinath Thilak Parepady Sundar ◽  
Tripthi Prakash Shetty ◽  
Bhanuprakash Bylapudi ◽  
Vikram Shetty ◽  
Chrysl Castellino ◽  
...  
Keyword(s):  
Prospective Study ◽  
Nerve Block ◽  
Anterior Region ◽  
Infraorbital Nerve ◽  
Outcome Variable ◽  
Posterior Teeth ◽  
Similar Action ◽  
Anterior Teeth ◽  
Greater Palatine Nerve ◽  
Palatal Mucosa

Introduction: Local Anaesthesia (LA) is the mainstay of any routine dental extraction. Accomplishing optimum anaesthesia with least pain and anxiety to patients is a challenge. Hence, modification of technique and application of routine dental LA to enhance patient comfort is the need of the hour. In this pursuit, a prospective cohort study was carried out to evaluate the effectiveness of greater palatine nerve block as an alternative to nasopalatine nerve block in anaesthetising the anterior palatal mucosa and to achieve optimum palatal anaesthesia. Aim: The primary outcome variable is to assess the extent of the anaesthetic effect of greater palatine nerve block in maxillary anterior palatal region. Materials and Methods: A total of 100 patients scheduled for the extraction of ipsilateral anterior and posterior maxillary teeth were included in this prospective study between June 2017 to June 2019. Palatal anaesthesia for all the extractions done was achieved only with greater palatine nerve block. After an interval of five minutes, the extent of palatal anaesthesia from the posterior palatal tissue to the anterior region was evaluated for both subjective and objective symptoms. Pain on the palatal mucosa was assessed using Numerical rating scale of 0-10. Post-evaluation, depending on the proposed tooth of extraction, buccal anaesthesia was achieved with Posterior superior alveolar nerve block for posterior teeth and infraorbital nerve block for anterior teeth. Results: Of the 100 patients administered with greater palatine nerve block, it was observed that in 36 patients (36%) had effectiveness in anaesthesia till central incisor, 28 (28%) patients had effectiveness in anaesthesia till lateral incisor, 20 (20%) patients had effective in anaesthesia till the canine and 16 (16%) patients anaesthetic effects were limited to posterior teeth. Overall, 84% had varied degree of positive anterior anaesthesia with greater palatine nerve block alone. Conclusion: Greater palatine nerve block was effective in providing anaesthesia to the posterior region till the premolars, with the extended complete anaesthesia in the anterior region with similar action as the nasopalatine nerve block administered to anaesthetise the anterior palate for extraction of the anterior teeth.

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