Tooth Crown Research Articles

> 42 ka human teeth from El Castillo Cave (Cantabria, Spain) Mid-Upper Paleolithic transition

Three deciduous tooth crowns were found in Unit 18B in El Castillo Cave (Spain), considered a transitional Middle-Upper Paleolithic Unit with numerous 14C dates with means earlier than > 42–44 ka cal. BP. Our goal was to describe these teeth, compare them to Neanderthal, Mousterian Modern Humans, and Early-Mid Upper Paleolithic fossils (through scatterplots and Z-scores), and analyze their morphology. The teeth consist of deciduous and isolated crowns (one ULdi1, one ULdm2, and one LRdm2) corresponding to three children, and all of them were modified by heavy occlusal and interproximal wear. Their length and breadth diameters, shown in the bivariate scatterplots, were similar to those of the teeth of several young Neanderthals. The Z-scores of the two crown diameters with respect to the Late Neanderthal, Qafzeh and Skhul, and Aurignacian-Gravettian series had values of approximately 0, while those of the altered MDs of the ULdm2 are just below − 1, except in comparison to the last group; the Z-scores of the BL diameters fall within the range of variability of the three series. Qualitative morphological comparisons highlighted several characteristics that were consistent with a Neanderthal taxonomic assignment. The combined archeological and anatomical-comparative study suggested the presence of three Neanderthal children in Unit 18, in a location considered a primary butchery area. The chronology and morphology of these teeth in the framework of the Middle to Upper Paleolithic transition are outstanding in the debate about the last Neanderthals and the unconfirmed, but possible, presence of a few groups of modern humans in Western Europe.

Who Is in Handicrafts: Tooth Morphology and Age Determination as Tools to Assess Vulnerable Dolphins Sotalia spp. Supplying the Trade of Artisanal Charms in Brazil

In Brazil, dolphins’ body parts are commonly used as traditional amulets, named as love-charms, while dolphins’ teeth are commercialized in handcrafted necklaces and bracelets. Recent studies on forensic genetics confirmed the Guiana dolphin,Sotalia guianensis, as the principal target of the love-charms trading, with specimens incidentally captured in gillnets suggested as the primary source. As additional support for these investigations, we characterized tooth morphotypes and ages of dolphins used in the construction of traditional crafts, with the main objective of detecting the dolphin species and population groups most affected by this trade. Teeth collected from necklaces, bracelets, and earrings, sold in public markets from three major cities of Northern and Northeastern Brazil (Belém = 99, São Luís = 4, and Fortaleza =15), were analyzed using four morphological measurements: tooth total length (TL), root diameter (RD), crown length (CL), and cingulum diameter (CID). An unweighted pair group method using arithmetic means (UPGMA), with Euclidean distances as a measure of dissimilarity, multivariate analysis of variance (MANOVA), and principal component analysis (PCA) were used to detect tooth morphotypes in the samples. Ages were obtained by counting the growth layer groups (GLGs) deposited in dentine. Two different groups of teeth were detected presumably belonging to the speciesSotalia guianensisandS. fluviatilis. Handicrafts showed a diverse age composition, ranging from 2 to 30 years, with a multimodal distribution (Mean =11 ± 7 SD, Median = 10, Mode = 4, 8, 19), similar to dolphin populations affected by fishery interaction. Results suggested that juveniles individuals and adults younger than 20 years, from bothSotaliaspecies, probably incidentally captured, are the principal source of handicrafts, and raise concern about the greater vulnerability of young age categories presented in this trade.

Breakage and displacement of the high-speed hand-piece bur during impacted mandibular third molar extraction: three cases

BackgroundThe high-speed hand-piece bur is one of the methods to perform tooth sectioning during the minimally traumatic extraction of impacted mandibular third molars. During tooth sectioning, the breakage of the bur might take place when it is improperly used. Three cases of the breakage and displacement of a high-speed hand-piece bur during extraction are reported, aiming to remind dental surgeons of this complication.Case presentationThe bur fragment in case 1 was embedded in the mandibular bone under the previously removed crown of tooth 48 and distal to tooth 47. The bur fragment in case 2 was embedded in the lingual edge of the socket and partly beneath the mucosa on the lingual side. The position of the bur fragment in case 3 was similar to that of case 1 but was completely embedded in the spongious bone. The three cases were performed by first-year residents, and all of the bur fragments were successfully removed by attending doctors after accurately locating them by radiological examination.ConclusionsIn order to avoid breakage of the high-speed hand-piece bur, the number of uses of the bur should be monitored and the integrity and state of the bur should be carefully checked. Moreover, light pressure with little lateral force should be used during tooth sectioning. If bur breakage and displacement occur, the retrieval protocol should be determined based on the imaging findings and conducted as soon as possible to avoid serious consequences.

The Effect of Primary Root Canal Treatment on Dentinal Tubule Penetration of Calcium Silicate–based Sealers during Endodontic Retreatment

IntroductionThe aim of this study was to evaluate the effect of previous root canal treatment on dentinal tubule penetration of calcium silicate–based sealers during endodontic retreatment and to compare 2 different (commonly used and modified) tubule penetration depth measurement techniques. MethodsThe crowns of mandibular premolar teeth were removed, and root canals were prepared (ProTaper Universal; Dentsply Sirona, York, PA) and obturated using AH Plus (AH; Dentsply DeTrey, Konstanz, Germany), MTA Fillapex (MTAF; Angelus, Londrina, Brazil), and WellRoot ST (WRST; Vericom, Gyeonggi-do, South Korea); 0.1% red Rhod-2 dye (Chemodex, St Gallen, Switzerland) was added to the sealers. After storage for 3 weeks (37°C, 100% humid), the following sealer combination subgroups were created (the sealer used during the primary root canal treatment/the sealer used during the retreatment, n = 8): AH/AH, AH/MTAF, and AH/WRST; MTAF/AH, MTAF/MTAF, and MTAF/WRST; and WRST/AH, WRST/MTAF, and WRST/WRST. Green Fluo-3 dye (0.1%) was added to the sealers during retreatment. Sealer penetration depths were measured at 8 points and averaged, and the ratio of the retreatment sealer to the initial sealer was recorded as the mean tubule penetration depth ratio in the first technique, whereas the percentage of the circumferential penetration area ratios of the retreatment and initial sealers was calculated in the second technique. Statistical analyses were performed using Kolmogorov-Smirnov, Kruskal-Wallis, and Mann-Whitney U tests. ResultsThe mean penetration depth of AH and MTFA was found to be higher at the coronal third region in the control groups (P < .05). Both methods showed a significant difference among the groups at the coronal and median regions (P < .05). The AH/WRST, MTAH/AH, MTAF/MTAF, MTAF/WRSTS, and WRST/WRST groups showed deeper tubule penetration (first technique, P = .01). Both techniques showed that the penetration depth of the sealers was the same at the apical region (P > .05), whereas a difference was found among the techniques at the coronal and median regions. The sealers used in the previous root canal treatment limited the penetration depth of the sealers used during the retreatment process (P < .05). When MTAF was used as the initial sealer, the penetration depth of the second sealer did not change, whereas if WRST was the initial sealer, the penetration depth of the sealers at the median and apical regions is negatively affected during the retreatment process (P < .05). ConclusionsPrevious root canal treatment affects the penetration depth of calcium silicate–based sealers. The use of AH Plus and MTA Fillapex during the retreatment process showed an advantage. Both measurement techniques showed similar performances at the apical region, whereas the results varied at the coronal and midcoronal regions; therefore, a more stable sealer penetration measurement technique is still necessary.

SUB GINGIVAL COMPLEX MICROBIAL BIOFILMS AND THEIR ERADICATION

Aim of study: The study was conducted to discuss and explain the ability to use a new methods for removal and even prevention of sub gingival biofilm. Biofilm is a three dimensional structure microbial community that first noted in the oral cavity as plaque on the crown of teeth which is called later supra gingival plaque to play a role in caries development . Un eliminated supra gingival plaque grow sub gingivaly to form more protected biofilm found in the gingival sulcus that is responsible for the conversion of physiological gingival sulcus (0-3 mm) to pathological pocket &gt; 3mm which play a role in the pathogenesis of different periodontal infections. Sub-gingival microbiota include mainly anaerobic proteolytic gram negative rods, these microorganisms considered as late colonizer which required the early colonizer to adhere primarily producing specific receptors, reducing the oxidation reduction potential (Eh ), cooperate metabolically within the biofilm. The study was based on a review submitted by: Cortés, et.al. (2011) titled “ Biofilm formation, control and novel strategies for eradication. The study took place during the period (Oct. 2022 - Feb. 2023) The challenges which faces oral microbiologist were characterizing the composition of sub gingival bacterial biofilm since most of them are un cultivable hence new molecular technique were facilitate these difficulties which in turn open horizons for eradication of these resistant microbial biofilm bacterial cells for novel treatment strategies and to prevent recurrence of periodontal infections.

In Vitro Study of Laser-Assisted Prefabricated Ceramic Crown Debonding as Compared to Traditional Rotary Instrument Removal.

This study compared the laser and rotary removals of prefabricated zirconia crowns in primary anterior and permanent posterior teeth. Sixty-two extracted teeth were prepared for prefabricated zirconia crowns cemented with resin-modified glass-ionomer cement. Specimens underwent crown removals by a rotary handpiece, or erbium, chromium: yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser. Pulpal temperatures, removal times, and scanning electron microscopy (SEM) examinations were compared. The average crown removal time for rotary and laser methods was 80.9 ± 19.36 s and 353.3 ± 110.6 s, respectively, for anterior primary teeth; and 114.2 ± 32.1 s and 288.5 ± 76.1 s, respectively, for posterior teeth (p < 0.001). The maximum temperature for the rotary and laser groups was 22.2 ± 8.5 °C and 27.7 ± 1.6 °C for anterior teeth, respectively (p < 0.001); and 21.8 ± 0.77 °C and 25.8 ± 0.85 °C for the posterior teeth, respectively (p < 0.001). More open dentinal tubules appeared in the rotary than the laser group. The rotary handpiece removal method may be more efficient than the laser with lower pulpal temperature changes. However, the laser method does not create noticeable tooth or crown structural damage compared to the rotary method.

Clinical Performance and Parental Satisfaction with Composite Strip Crown and Prefabricated Zirconia Crown for Primary Anterior Teeth: A Randomized Clinical Trial

To compare clinical performance and parental satisfaction with composite strip crown and prefabricated zirconia crown for primary anterior teeth. The study compares clinical evaluation and parental satisfaction of two different crowns for primary anterior teeth. A total of 102 teeth in each group selected between ages 3 and 6 years, who met the inclusion criteria, were randomly allocated into two groups for further evaluation. Group A for strip crowns (55 teeth) and group B for zirconia crowns (47 teeth). The crowns were evaluated clinically with various criteria like-color match, crown retention, gingival health, crown contour, opposing tooth wear, marginal integrity, and recurrent caries. The samples were also evaluated for parental satisfaction based on 5-point Likert scale and child liking was also recorded with Smiley face Likert scale at baseline, 3 and 9 months. Statistical analysis was done using Chi-square test (p <0.05). Zirconia crowns showed better color match, crown retention, crown contour, and gingival health. Strip crowns showed more discoloration and chipping of material over a period of time. None of the samples showed opposing tooth wear, open margins, and recurrent caries in strip and zirconia crown group. Parents and children both were highly satisfied with zirconia crowns. Clinically zirconia crowns showed higher success rate as compared to strip crowns and parental overall satisfaction was higher for zirconia crowns. Zirconia crowns exhibited a higher clinical performance and parental satisfaction; hence, if affordability is out weighted, zirconia crown stands better with esthetics of the child.

Diagnostic value of cone beam computed tomography in complex and compound odontomas: a systematic review and open classification matrix

Objective: Firstly, this review aims to analyse the recent literature about three-dimensional (3D) diagnostic imaging in complex and compound odontomas and compare it to two-dimensional (2D) imaging. Panoramic radiographs help to&#x0D; evaluate the vertical position of odontomas, and occlusal radiographs are used to evaluate the proximity to adjacent teeth. However, cone beam computed tomography (CBCT) can offer volumetric images, and therefore, a more accurate three-dimensional analysis. Secondly, this research aims to construct an open classification matrix for complex and compound odontomas for dentomaxillofacial CBCT radiology protocols based on a systematic literature review.&#x0D; Material and methods: Two systematic literature searches were conducted in PubMed (Medline), on 2 February 2022 concerning classification systems, and on 5 February 2022 concerning CBCT images.&#x0D; Results: In total, these searches revealed 391 papers by reviewing the databases mentioned above. Six articles were selected for inclusion on classification of odontomas and 13 articles were found on CBCT imaging. Consequently, the&#x0D; construction of an open classification matrix for compound and complex odontomas for dentomaxillofacial CBCT radiology protocols was performed using these 19 articles.&#x0D; Conclusions: CBCT offers a more precise position and accurate diagnosis of complex and compound odontomas compared to 2D imaging. Consequently, it enhances the detailed view of the site (multiple or unique), location (intraosseous, partially or completely extragnathic), size, extension (bony expansion, thinning or perforation cortical bone), density and type (denticulo type, particle type, denticulo-particle type, denticulo-amorphous type, amorphous tissue), relationship (with the crown or root of the definitive tooth), adjacent teeth resorption (deciduous or definitive), adjacent teeth (retention or impaction), and distance with adjacent structures (inferior alveolar nerve, sinus maxillaris), as well as adequate surgical planning. Moreover, this research presents an open classification matrix for the most complete description of compound and complex odontomas when analysing CBCT imaging.&#x0D;

Editorial: Dental Ceramics: From Science and Technology to Clinical Application

Editorial: Dental Ceramics: From Science and Technology to Clinical Application

Osteological and taxonomic reassessments of Sahaliyania elunchunorum (Dinosauria, Hadrosauridae) from the Upper Cretaceous Yuliangzi Formation, northeast China

ABSTRACT The osteology and taxonomy of the lambeosaurine Sahaliyania elunchunorum from the upper Yuliangzi Formation (middle Maastrichtian) are reevaluated herein. Based on detailed morphological comparisons among hadrosauroids, we argue that Wulaga lambeosaurine specimens, most of which were previously ascribed to S. elunchunorum, display a combination of features that is typical of Amurosaurus riabinini from the upper Udurchukan Formation (middle Maastrichtian) at the Blagoveschensk locality. This combination includes several anterodorsally-posteroventrally oriented lateral foramina of the maxilla with a very large last one partially obscured by the ventral extremity of the jugal contact, a narrow infratemporal region of the jugal that is ∼70% as wide as the orbit, a relatively low anterior third of the strongly dorsally concave sagittal crest of the parietal, mesiodistally wide maxillary tooth crowns (∼1.2–1.3 teeth per cm), the sternal posterolateral process slightly shorter than the anteromedial plate, and a gently ventrally deflected preacetabular process of the ilium. Considering the osteological similarities and the fact that the Yuliangzi and Udurchukan formations were deposited synchronously in the same basin, S. elunchunorum is regarded here as a junior synonym of A. riabinini. Approximately 70% of the complete Amurosaurus fibulae from the Wulaga bonebed exhibit a total length of more than 85 cm that probably corresponds to the adult stages. Histological sections from these fibulae are moderately remodeled by dense secondary osteons, with poorly developed vascularization of primary osteons along fibrolamellar bone in the outer cortex. The phylogenetic analysis of Lambeosaurinae recovers a sister-taxon relationship between Amurosaurus and Lambeosaurus.

Treatment of Altered Passive Eruption Type 1B: A Case Report

Background: The appearance of the gingival tissue around the teeth plays an important role for the aesthetics. Abnormalities in symmetry and contour of gingival tissue affects the harmonization of the teeth’s appearance. Excessive gingival display (EGD) or gummy smile, short clinical crown of tooth are frequent complaints of patients. There are various factors that can cause a gummy smile and a short clinical crown, one of which is altered eruption. The procedure that can provide a solution to this aesthetic, periodontal and restorative problem is crown lengthening. Crown lengthening is a surgical procedure that aims to remove periodontal tissue to increase the clinical length of the dental crown, the crown-lengthening procedure can be achieved with or without bone reduction.&#x0D; Objective: To describe the management of altered passive eruption type 1B by crown lengthening with osteotomy procedure.&#x0D; Case Report: A 20-year-old female patient presented to the periodontics clinic of RSGM Soedomo UGM, with a complaint of excessive gum appearance with her right upper front tooth looking short when she smiled. The patient was diagnosed with altered passive eruption. The treatment was crown-lengthening surgery with osteotomy.&#x0D; Conclusion: Crown lengthening is an effective treatment to retrieve functional and aesthetic disturbances associated with altered passive eruption.&#x0D; Keywords: gummy smile, altered passive eruption, crown lengthening surgery

Gingival health status of patients treated with full veneer crown and contra lateral natural tooth : A comparative study

Aim: The aim of this study was to compare the gingival health of patients treated with full veneer crown (FVC) restoration with the contralateral natural tooth of that patients in different stages of treatment. Materials and methods: This study compared the gingival health status of 30 endodontically treated posterior teeth with FVC and 30 contralateral natural teeth of 19 patients in terms of gingival index, and plaque index. These patients have been examined from July 2017 to June 2019 in the Dept. of Prosthodontics, Bangabandhu Sheikh Mujib Medical University (BSMMU) Hospital. The gingival health was assessed with gingival index and plaque index by Leo H in different stages of treatment, also compared with the contralateral natural teeth. Collected data were analyzed using SPSS software (version 22) according to the study objectives. Results: Tooth with FVC restoration found high gingival index and plaque index compared to a contralateral natural tooth in different stages of treatment. The mean differences of the gingival index were not significant at baseline, 4th month visits, but it was significant, and highly significant at 8th month, 12th month follow-up visits respectively. The mean differences in plaque index were found significant in all visits except 12th month visit. The gingival index and plaque index increased from baseline to 4th, 8th,12th month visits gradually both in abutments and contralateral natural teeth. Conclusion: If the FVC is fabricated with maintaining proper anatomical contour, equigingival margin with proper marginal adaptation, despite maintaining oral hygiene as well as the general health of patients there is a chance of development of adverse effects on gingival health in comparison to the contralateral natural tooth. Update Dent. Coll. j: 2022; 12 (1): 17-21

Historical significance and taxonomic status of Ischyrodon meriani (Pliosauridae) from the Middle Jurassic of Switzerland.

Ischyrodon meriani is an obscure pliosaurid taxon established upon an exceptionally large tooth crown of a probable Callovian (Middle Jurassic) age that originates from Wölflinswil, Canton of Aargau, Switzerland. Despite being known for almost two centuries, the specimen remains poorly researched. Historically, I. meriani has been associated, or even considered conspecific, with Pliosaurus macromerus and Liopleurodon ferox. However, neither of the two hypotheses have been tested through detailed comparisons or using modern quantitative methods. Here, we redescribe the type of Ischyrodon meriani, illustrate it, and compare to teeth of thalassophonean pliosaurids, with special focus on Jurassic representatives of the clade. Multivariate analyses show close similarities to L. ferox but comparable structures to those of I. meriani, including a distinctive pattern of the apicobasal ridges, are also observable in some mid-Cretaceous brachauchenines from the ‘Polyptychodon’ assemblage of East and South East England. While it is likely that I. meriani represents a Liopleurodon-like taxon, or is indeed conspecific with L. ferox, which would make I. meriani the proper name for the species, any such taxonomic considerations are hindered by the fragmentary nature of the type specimens of both these taxa as well as limited knowledge of the dental variability within and between individual jaws of L. ferox. Currently, I. meriani is best treated as a nomen dubium. Finally, we discuss the potential implications of I. meriani being conspecific with L. ferox, and additionally provide a commentary on the taxonomic status of Liopleurodon.

Red fluorescence for assessing longitudinal tooth fractures

BackgroundThis study was designed to determine whether autofluorescence emitted from longitudinal tooth fractures (LTFs) differs between fracture types, with the aim of determining which clinical factors are related to red fluorescence at the fracture line. MethodsThirty-three extracted teeth were classified into cracked teeth, split teeth, and root fractures using LTF types according to the American Association of Endodontists classification. The types of LTFs were identified using an operating microscope. LTF autofluorescence was captured using a fluorescence technique. Clinical examinations were performed using the preoperative factors from clinical and radiographic findings. ResultsRed fluorescence was identified in 82% and 83% of cracked and split teeth, respectively. None of the vertical root fractures exhibited red fluorescence (p<0.001). When red fluorescence was identified on the outer tooth surface, it penetrated into the crack line, but fluorescence that was not red at the tooth surface did not penetrate the fracture line. Among the examined preoperative clinical factors, differences between the presence and absence of red fluorescence were identified for sinus tract formation (p = 0.021), and radiographic features (p = 0.027). Regression analysis revealed a significant factor related to the red fluorescence, with sinus tract formation having a negative effect on red fluorescence (odds ratio [OR]=0.09). The presence of comprehensive periradicular lesions in radiography had a positive effect on red fluorescence (OR=5.04). ConclusionsCracks originating from tooth crowns in certain types of LTFs were associated with red fluorescence, and cracks with red fluorescence were associated with extensive periodontal bone resorption around the teeth roots.

FOLLICULAR CYST ASSOCIATED WITH CHOLESTROL CLEFTS -A CASE REPORT

Dentigerous cyst is the intraosseous odontogenic cyst mostly associated with the impacted or unerupted teeth. They are rd rd usually accompanied with the crowns of the permanent teeth especially mandibular 3 molars, canines and 3 molars of maxilla and rarely in the anterior of the maxilla. They often grow as a larger cyst and also affects the symmetry of face, disturbance of dentition and predisposing the fractures to the jaw. Dentigerous cysts if left untreated could cause serious complications as they have capacity to develop into rd other malignancies. This case report is about the dentigerous cyst with cholesterol clefts in the mandibular 3 molar region which was been treated.

An Improved Equivalent Magnetic Network Model of Modular IPM Machines

This article develops an improved equivalent magnetic network (EMN) model for analysis of a modular interior permanent magnet (IPM) machine. First, focusing on the local magnetic saturation, the stator tooth crown is divided into three parts based on its structure and flux density distribution. To model the specific flux path, the tooth tips on both sides are approximated to right-angled trapezoids and the middle part is divided into isosceles trapezoid. Second, an improved air-gap model is proposed, which divides the air-gap magnetic network into three layers. The middle network uses cross-shaped mesh (CS-M) elements to represent the path of tangential and radial fluxes. The top and bottom layers are composed of parametrized nonlinear permeances between stator, rotor edge nodes, and middle network nodes, whose values are the function of angle respect to CS-M elements. In this way, as the machine rotates, the structure of the EMN model can be kept invariant, and only permeances of bottom layers should be modified. Then, the EMN model is extended to the analysis of the machine with skewed stator. The accuracy and effectiveness of the proposed EMN model are verified through comparisons with finite element analysis and experimental tests.

Биомеханическое сравнение керамических, титановых и хромкобальтовых штифтовых вкладок при замещении посттравматических дефектов зуба

The aim of the study is the biomechanical substantiation of restoration of tooth crowns destroyed due to trauma using ceramic post inlays. Materials and research methods. In order to experimentally compare the strength of pin inlays, tooth root and ceramic crown depending on the material of the inlays, three-dimensional mathematical modeling of the stress-strain state of the pin structure using the method of finite element analysis was carried out. The physical and mechanical properties and size of a single-rooted tooth with a fractured crown (upper central incisor), a ceramic crown and a peg inlay made of a chrome-cobalt alloy, titanium or ceramics corresponded to the natural ones. Calculations were performed using the properties of both the devital and the intact tooth. Situations of early operation of the post construction with close contact of the root, inlay, and crown, as well as possible decay of tooth tissues along the edge of the crown in the long-term operation of the construction were simulated. A functional load of 150N was applied to two areas: the incisal edge and the upper third of the palatal surface of the crown on post inlays with a change in load direction from 0 to 90°. Research results and their analysis. According to the data of mathematical modeling of functional load, the strength of a post-traumatic tooth defect replacement is sufficient when using both metal and ceramic post inlays; changes in physical and mechanical properties of the tooth with increasing time from the moment of devitalization increase stress in the ceramic crown, and root failure along the edge of the crown causes the ultimate stress at a horizontal shift of load direction. The biomechanical rationale allows: in case of complete destruction of the crown part of the tooth — to recommend milled dowel ceramic inlays as a support of metal-free artificial crowns; to stick to the technology of their fixation in the root canal and of the fixation of crowns to the inlays; to ensure a strict dispensary of patients with a ceramic crown on milled dowel ceramic inlay to detect and to eliminate tooth root caries in the long term; to provide direction of functional load within 30° from the axis of the restored tooth during prosthetics.

The role of dispersal, selection intensity, and extirpation risk in resilience to climate change: A trait‐based modelling approach

AbstractAimFactors that make species resilient to climate change can be difficult to study with empirical data because conditions cannot be experimentally controlled. We used trait‐based evolutionary ecological agent‐based modelling to understand how dispersal, selection, extirpation, and other factors contribute to resilience under three climate change scenarios to test the extent to which high dispersal rate contributes to persistence of species and the extent to which they occupy large geographic ranges on an evolutionary time‐scale involving speciation, dispersal, gene flow, and extinction.LocationHesperia (an imaginary continent with controlled environmental heterogeneity).Major taxa studiedModelled mammalian herbivore clade with 16 terminal species, each of which is a metapopulation with a variable number of local populations.MethodsWe used NetLogo to model trait‐based biotic responses to climate change in an environmentally heterogeneous continent in an evolving clade, the species of which are each represented by local populations that disperse and interbreed; they also are subject to selection, genetic drift, and local extirpation. We simulated mammalian herbivores, whose success depends on tooth crown height, vegetation type, precipitation and grit.ResultsWe found that high dispersal probability usually allowed species to successfully track their ancestral habitat as the continent's geography was altered by climate change. However, tracking was insufficient to allow species’ traits to adapt to novel habitats that arose through the climate change process. High dispersal rates combined with moderate plasticity (lower extirpation risk) facilitated occupation of novel habitats, as did weak selective regimes.Main conclusionsThe interaction between dispersal, probability of local extirpation, and selection intensity were jointly required to understand the likelihood of species survival and how widespread they would be. Diversity and geographic occupancy were maximized when parameters facilitated evolutionary adaptation to novel habitats. High rates of dispersal were sufficient for habitat tracking but insufficient by themselves to allow occupation of newly emerged environments.

Hereditary Gingival Fibromatosis: An Unusual Case Report

Overgrowth of keratinized gingival tissues is a common condition and is described under a variety of names. Causes of such enlargement can be medications, hereditary, and/or local irritating factors. Hereditary gingival fibromatosis is a rare condition that can occur as an isolated disease or as part of a syndrome or chromosomal abnormality. In severe cases, the gingival enlargement may cover the crowns of teeth and cause severe functional and aesthetic concerns. Here, we present a case of an 8-year-old girl with severe enlargement of gums in the maxilla and mandible. The diagnosis was made based on clinical examination and family history.

Ablation of FAM20C caused short root defects via suppressing the BMP signaling pathway in mice.

Short root defects are prone to cause various periodontal diseases and lead to tooth loss in some serious cases. Studies about the mechanisms governing the development of the root are needed for abetter understanding of the pathogenesis of short root defects. The protein family with sequence similarity20 groupC (FAM20C) is aGolgi casein kinase that has been well studied in the development of tooth crown formation. However, whether FAM20C plays arole in the development of tooth root is still unknown. Thus, we generated Sox2-Cre;Fam20cfl/fl (cKO) mice, in which Fam20c was ablated in both the dental epithelium and dental mesenchyme, and found that the cKO mice showed severe short root defects mainly by inhibiting the development of dental mesenchyme in the root region. In this investigation, we found morphological changes and differentiation defects, with reduced expression of dentin sialophosphoprotein (DSPP) in odontoblasts of the root region in cKO mice. Furthermore, the proliferation rate of apical papillary cells was reduced in the root of cKO mice. In addition, the levels of bone morphogenetic protein4 (BMP4) and phospho-Smad1/5/8, and that of Osterix and Krüppel-like factor4 (KLF4), two downstream target molecules of the BMP signaling pathway, were significantly reduced in the root of cKO mice. These results indicate that FAM20C plays an essential role in the development of the root by regulating the BMP signaling pathway.