Tooth Crown Research Articles

Новый род лучеперых рыб (Eurynotoidiformes) из уржумских отложений Республики Татарстан (местонахождение Ключевской овраг)

New genus and species of eurynotoidiid actinopterygians (Eurynotoidiformes), Kluchevichthys praeclarus gen. et sp. nov., is described from the uppermost Urzhumian (Kluchevskoy Ovrag locality), Tetushi District, Republic of Tatarstan. The holotype of а new form is an almost complete, non-deformed skeleton. The diagnostic characters of K. praeclarus were obtained in the morphology of the skull roof bones, dental system, scales and fins. The morphology of the marginal dentition, combining the tricuspid pattern of tooth crowns with the conical shape of all their apices allows positioning of a new taxon at the base of most phylogenetic branches of herbivorous Eurynotoidiformes having more specialized condition of the dental system, which corresponds well to stratigraphic data.

Nutritional supplementation, tooth crown size, and trait expression in individuals from Tezonteopan, Mexico

Nutritional supplementation, tooth crown size, and trait expression in individuals from Tezonteopan, Mexico

Maxillofacial Bone Fractures in Children and Adolescents in Saudi Arabia: A Systematic Review.

Facial injuries, including maxillofacial trauma (MFT), are common in children and adolescents due to their age and bone maturation stage. Children's injuries are less common than adults' due to parental supervision and the flexibility of the facial bone. Causes of maxillofacial bone fractures (MFBF) vary based on socioeconomic, cultural, and environmental factors. Management of MFBF in children and adolescents should consider their growth and development stage. A systematic review is needed to understand the prevalence, pattern, and distribution of MFBF in Saudi Arabia. This systematic review aimed to identify papers on MFBF in children and adolescents in Saudi Arabia using the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) statement. The search strategy involved searching electronic databases like PubMed/Medline, Web of Science, and Ebsco. The review included full-text original research papers, with inclusion criteria including English publications, human studies, and no restrictions on sample size, gender, date, or language. The selection process involved screening titles and abstracts, evaluating full texts, and identifying relevant studies. Data extraction involved two authors individually assessing selected studies. The PRISMA flow diagram of the literature search revealed that 26 papers were identified, of which 15 remained after excluding duplicates. After screening titles and abstracts, 10 articles were removed, and five papers were assessed for eligibility. Four papers met the inclusion criteria for the systematic review. The studies examined 1447 patients for the presence of MFBFin different regions. The majority of MFBF were caused by falls and road traffic accidents (RTAs) in children and adolescents. Mandibular fractures were the most common, followed by maxillary fractures. The majority of patients had tooth/teeth avulsions, followed by tooth luxation and crown fractures. Only one study described investigation methods for MFBF diagnosis. The systematic review reveals a high prevalence of MFBFamong children and adolescents in Saudi Arabia, primarily due to falls and RTAs. The mandible is the most frequently fractured bone, and many children have concomitant teeth involvement. To reduce MFBF, effective initiatives and parental awareness strategies are recommended.

Edge chipping patterns in posterior teeth of hominins and apes

Chip scars in fossil teeth are a lasting evidence that bears on human evolution. Chip dimensions in posterior teeth of hominins, apes and white-lipped peccary (Tayassu pecari) are measured from published occlusal images. The results are plotted as D/Dm vs. h/Dm, where h, D and Dm denote indent distance, chip width and mean tooth crown diameter. The hominin species follow a similar pattern where D/Dm monotonically increases up to h/Dm ≈ 0.3. The behavior for the apes is characterized by two phases. In the first, h/Dm monotonically increases up to h/Dm ≈ 0.26 while in the second (h/Dm ≈ 0.26 to 0.42), D/Dm experiences a drastic change in behavior. The interpretation of chip morphology is assisted by results from controlled spherical indentation tests on extracted human molars. This study shows that in addition to the commonly recognized chipping due to cusp loading, a chip may also initiate from the inner wall of the tooth's central fossa. Accordingly, it is suggested that the chipping in hominins generally initiates from a (worn) cusp while that in apes involves cusp loading up to h/Dm ≈ 0.26 and fossa loading thereafter. The behavior for T. pecari is much similar to that of the apes. The fossa chipping is facilitated by a consumption of hard, large-size diet (e.g., plants, roots, barks and nuts) and presence of broad central fossa, conditions that are met in apes. Finally, a simple expression for the critical chipping force Pch due to fossa loading is developed.

Survival of pre-formed zirconia crowns in primary teeth: A prospective practice-based cohort study.

Survival of pre-formed zirconia crowns in primary teeth: A prospective practice-based cohort study.

A Huge Infected Dentigerous Cyst Occupying the Maxillary Sinus

A dentigerous cyst (DC) ranks as the second most common odontogenic cyst after a radicular cyst arising from the crowns of impacted, embedded, or unerupted teeth. DC frequently causes the corresponding tooth to be displaced into an ectopic location, such as the sinus cavity in the maxilla. Surgical treatment involves extracting the tooth and enucleating the cyst using a conservative intra-oral approach or endoscopic surgery. We report a rare case of a 25-year-old woman with maxillary third molars inside the maxillary sinus attached to a dentigerous cyst and treated with Caldwell Luc surgery through an intraoral approach.

Body Height Estimation According to Deciduous Dental Crown Height in a Peruvian Sample of Preschool Children.

Odontometry and body height are distinctive biological traits, making their relationship relevant in the identification of individuals. The objective of this study was to estimate body height according to the height of the crown of deciduous teeth in Peruvian preschool children. This analytical study was applied to a calculated sample of 204 preschoolers between 3 and 5 years of age (34 per sex/age group) with fully erupted upper anterior deciduous teeth (from #53 to #63). Measurements included body height with a stadiometer (106 ± 6.56 cm; 94-123 cm) and crown height from canine to canine (3.06 mm in #62 to 8.13 mm in #53) in models with digital vernier (intraclass correlation coefficient ≥ 0.781). Linear regression models included calculation of the regression coefficient (β) to predict height based on crown height for each deciduous tooth at a significance level of P < 0.05. There was no correlation between body height and crown height by tooth type in the total sample (P ≥ 0.05), but there was in a 3-year-old female in #52 (r = 0.4: moderate) and a 5-year-old female in #53 and #63 (r = 0.36-0.38: low) (P < 0.05). Body height prediction equations are shown according to crown height per tooth and sex/age groups. The regressions were significant, explaining 13%-18% of 3-year-old females in #53 and #52 (1.85-1.86 cm error) and 5-year-old females in #53, #51, and #63 (4.61 at 4.63 cm error) (P < 0.05). The odontology method using crown height of the upper anterior deciduous teeth estimated body height in Peruvian girls of 3 and 5 years of age. The teeth are resistant to traumatic forces so these could be used as a body height estimation parameter for forensic human identification.

Long-term performance of ceramic in/-onlays vs. cast gold partial crowns – a retrospective clinical study

ObjectivesTo assess the long-term clinical performance of ceramic in-/onlays (CIOs) and cast gold partial crowns (CGPCs) in posterior teeth in terms of success, survival, complications (biological, technical) and quality.Material and methodsIn a retrospective study, a total of 325 patients were recorded after up to 24.8 years (mean 13.9 ± 3.8 years) having (pre-)molars restored with CIO (Empress I, Ivoclar Vivadent, n = 161) and CGPC (Degunorm, DeguDent, n = 164) by supervised undergraduate students. A total of 296 restorations were assessed clinically and radiologically in healthy and endodontically treated teeth using modified United States Public Health Service (USPHS) criteria. Cumulative success and survival rates of the restorations were calculated using Kaplan–Meier estimates. Biological and technical complications were recorded. Status of oral health comprising caries risk and localized periodontitis were assessed.ResultsThe cumulative success rates of CIOs were 92.1% and of CGPCs 84.2% after mean service times of 14.5 years. The annual failure rates of total service times were 0.5% in teeth restored with CIO (n = 155) and 0.7% in teeth restored with CGPC (n = 163). The cumulative survival rates of CIOs were 93.9% after a mean service time of 15.2 years and decreased to 91.7% after 23.5 years. The cumulative survival rates of CGPCs were 92.6% after a mean service time of 14.9 years and 91.8% after 23.5 years. Complications in CIOs (n = 149) were ceramic fracture (6.7%), secondary caries (4.7%), endodontic complication (2.7%) and tooth fracture (1.3%) compared to CGPCs (n = 147) with endodontic complication (8.8%), secondary caries (4.8%) and decementation (2.0%). Endodontically treated teeth restored with CIO or CGPC revealed significantly less often success compared with corresponding vital teeth (p = .02). CIOs and CGPCs revealed clinically and radiographically good and excellent qualities with 71.8% (107/149) and 68% (100/147) without any significant differences regarding type of restoration.ConclusionsBoth CIOs and CGPCs achieved high survival rates up to 24.8 years when performed by supervised undergraduate students. The longevity of the restorations may benefit from the intraoral repair of accessible defects and, in case of pulp infection or necrosis, an adequate endodontic management.Clinical relevanceCIOs and CGPCs made by supervised undergraduate students are proper restoration types in posterior teeth in the long-term. An adequate preparation design, meticulous care in the inserting technique and constant biofilm removal due to proper oral hygiene combined with professional maintenance care are substantial. The clinical long-term performance was mostly limited by ceramic fractures in CIOs and endodontic complications in CGPCs.

АНАЛИЗ 3D-ЦЕФАЛОМЕТРИЧЕСКИХ ПАРАМЕТРОВ ЧЕРЕПА И 3D-БИОМЕТРИЧЕСКИХ ПАРАМЕТРОВ ВИРТУАЛЬНЫХ ЦЕЛОСТНЫХ ЗУБНЫХ ДУГ ПРИ ИХ ДИСТАЛЬНОМ СООТНОШЕНИИ ПО ДАННЫМ РАСШИРЕННОЙ КОНУСНО-ЛУЧЕВОЙ КОМПЬЮТЕРНОЙ ТОМОГРАФИИ

Objective. To improve technically the diagnostic analysis of 3D-cephalometric parameters of the skull and 3D-odontometric and 3D-biometric parameters of the complete dentition with distal occlusion during the period of permanent dentition according to extended cone-beam computed tomography. Methodology. 134 patients aged 17–35 years with a “distal occlusion” diagnosis were 3D-cephalometrically and 3D-biometrically examined.The parameters of the tragus width and diagonal of the skull on both sides were studied using virtual dynamic 3D-reformats of the skull. The gnathic skull index was calculated and the mesognathic, dolichognathic and brachygnathic skull types were determined. The width, thickness and height of permanent teeth crowns were measured using virtual dynamic 3D-reformats of diagnostic jaw models. Dental types (normodont, microdont, macrodont) of the complete dentition with distal occlusion were determined and abnormal forms (V-shaped, saddle-shaped, triangular, trapezoid, asymmetric) of dentition were pictured. The arcade index was calculated and gnathic types (mesognathic, dolichgnathic, brachiagnathic) of dentition were determined. Severity of the sagittal occlusal curve of Spee was determined on both sides. Results. Mesognathic and dolichognathic types of skull were diagnosed most often; the brachygnathic type was the least common. The combined dental type was in the lead, followed by the microdont and normodont types, the macrodont type was the least common among the dental types of dentition. Analysis of the abnormal shapes of dentition showed a trapezoidal shape predominance in both jaws. The dolichognathic type was most often to be found smong the gnathic types of dentition on both jaws. When analyzing the severity of sagittal occlusal Spee curves, the sharply concave curve was the leader on both sides. Conclusion. Individual 3D-cephalometric and 3D-biometric parameters obtained from extended cone-beam computed tomography can be used to simplify diagnosis, prognosis and to improve the effectiveness of orthodontic treatment.

Paedodontic preformed crowns in primary teeth and relative degree of dental wear.

Prosthetic rehabilitation of deciduous teeth in paediatric age using pre-formed crowns has been considered one of the best methods of dental restoration since their introduction. Their main advantages are related to durability, longevity and a low rate of recurrent cavities. Since stainless steel crowns do not coincide with aesthetic needs of parents and patients, preformed paedodontic crowns made of zirconia and nano-hybrid composite was introduced. The aim of the study is to evaluate the degree of wear on the enamel and on themselves of the different paedodontic crowns. Nine bovine teeth and nine paedodontic crowns for deciduous molars were selected for the study, three of which in zirconia, three in nano-hybrid composite and three in stainless steel. Wear test was carried out on the Rtech™ Instruments tribometer applying a force of 50 N. After that, both the bovine teeth and the paedodontic crowns were observed using a stereo microscope (Zeiss Stemi C-500) and a scanning electron microscope (SEM, Cambridge Stereoscan 440). The areas of wear were calculated with a software [ImageJ, version 1x, Wayne Rasband, Maryland, USA]. Pre-formed paediatric crowns in zirconia, nano-hybrid composite and stainless steel are a valid aid for the restoration of deciduous teeth and do not compromise the physiological wear characteristic of the phases of the dental exchange. The stainless steel crown is preferable for the restorations in the posterior sectors as its behaviour is the most similar to that of a natural tooth. Zirconia and nano-hybrid composite crowns showed an inversely proportional behaviour between their wear volume and that of the opposing tooth.

Early ray‐finned herbivores: the dental system of Eurynotoidiidae (Actinopterygii; middle–late Permian, European Russia) and implications for palaeobiology and palaeoecology

AbstractEurynotoidiformes are a little‐known group of actinopterygian fishes from the Permian of European Russia, characterized by the possession of multicuspid marginal teeth arranged in a single row. Morphologically, the teeth resemble those of Recent Cichlidae, Acanthuridae, Siganidae or Serrasalmidae, suggesting similar trophic adaptations related to herbivory. Tooth histology is similar to the majority of basal actinopterygians (composed of dentine, acrodin and collar enamel). Teeth are ankylosed in their attachment, and labial pleurodont in implantation, strengthening the tooth. The multicuspid tooth crowns derive from conical teeth of predatory or omnivorous ancestors, analogous to the evolution of multicuspid teeth in cichlid fishes. Tooth replacement in eurynotoidiforms is most comparable to an alternating pattern, with a possible simultaneous, unilateral replacement occurring in the whole jaw, similar to characiform fishes. Replacement teeth were formed extraosseously. Teeth of the inner dental arcade were conical. Based on comparisons with the teeth of extant actinopterygians specialized for herbivory, along with functional morphological analysis and consideration of wear patterns, we hypothesize that eurynotoidiforms represent the oldest known actinopterygians specialized for herbivory. Several strategies of herbivory in Recent actinopterygians were already realized by eurynotoidiforms as early as the Late Palaeozoic (middle and late Permian): grazing/cutting filamentous algae (Lapkosubia spp., Isadia suchonensis), browsing/biting off macrophyte fragments (Isadia aristoviensis), scraping/harvesting periphyton from hard substrates (Isadia opokiensis, I. arefievi). However, notable morphological differences in the jaws (elongate) and tooth arrangement (homodont along the jaw, functional teeth separated) suggest that this Permian experiment in herbivory followed different pathways compared to extant taxa.

Canine sexual dimorphism in crown and root dimensions: a cone-beam computed tomographic study.

The primary step in forensic odontological analysis is sex determination. The present study is one of the few studies that evaluated the accuracy of the combination of canine tooth root length and crown measurements for sex determination. The study sample comprised 196 cone-be am computed tomographic scans of individuals aged 20-80 years distributed in five age categories: 20-29, 30-39, 40-49, 50-59, and 60+ years old. Different parameters, such as width, length, and ratio measurements for the crown and root of each maxillary and mandibular canine tooth, were examined and recorded. The findings indicated that maxillary canines had greater sex dimorphism ability (87.3%) than mandibular canines (80.6%). Total tooth length and root length of maxillary canine were the most pronounced variables in the differentiation of sex groups. When the combination of the mandibular and maxillary measurements was considered, the accuracy for sex dimorphism was 85.7%. By using ratio variables, the accuracy was reduced to 68.9%. According to the findings of this study, total tooth length and root length are the most discriminant variables of canine teeth. These variables are more reliable sex indicators than crown measurements.

The impact of apicobasal ridges on dental load-bearing capacity in aquatic-feeding predatory amniotes

AbstractApicobasal ridges are longitudinal ridges of enamel that are particularly common in several clades of aquatic-feeding predatory amniotes, including Plesiosauria, Ichthyosauria, Mosasauridae, Crocodylia, and Spinosauridae, as well as some early members of Cetacea. Although the repeated evolution of these dental ridges in unrelated clades suggests an adaptive benefit, their primary function in feeding is debated. Hypothesized functions range from increasing tooth strength to improving prey puncture or removal efficiency, but these have never been quantitatively tested. This study utilizes finite element analysis (FEA) to assess the impact of apicobasal ridges upon tooth crown strength in aquatic-feeding amniotes. Drawing on morphometric data from fossilized tooth crowns, a set of digital models was constructed to calculate the performance of smooth and ridged tooth variants under simulated bite force loadings. The similarities in overall stress distribution patterns across models of the same tooth shape, regardless of the presence or morphology of ridges, indicate that apicobasal ridges have little impact on stress reduction within the tooth crown. Ultimately, these findings suggest that apicobasal ridges have a minimal role in improving crown strength and form a framework for future research into the remaining hypotheses.

Computed tomographic investigation of a hatchling skull reveals ontogenetic changes in the dentition and occlusal surface morphology of Hadrosauridae (Dinosauria: Ornithischia)

CMN 8917 is a small, partial skull of a duck-billed dinosaur from the upper Campanian DinosaurPark Formation in what is now Dinosaur Provincial Park, Alberta. It represents one of the few nestling-sized juvenile hadrosaurines known to date. Support for this phylogenetic placement includes a narial vestibule not enclosed within the premaxillary dorsal and lateral processes, the presence of an anterodorsal maxillary process, and a maxillary dorsal process that is longer anteroposteriorly than dorsoventrally. The skull also possesses tooth traits traditionally associated with lambeosaurines, such as secondary ridges on some maxillary and dentary tooth crowns, and denticulation on some maxillary tooth crowns. The occurrence of these features in a juvenile hadrosaurine suggests that they were modified during ontogeny, calling into question their taxonomic utility for identifying juvenile specimens. The dentary teeth of CMN 8917 are similar to those of many adult hadrosaurids in that they possess a concave occlusal surface with steeper lingual and shallower buccal wear zones. This differs from the occlusal surface morphology present in some other juvenile hadrosaurids, which suggests interspecific differences in dental battery development—possibly reflective of dietary differences—occurred during early ontogeny in some taxa.

Effect of Post-Processing Heat Treatment on Micro-Contact Damage of Zirconia-Reinforced Lithium Silicate Dental Materials.

Zirconia-reinforced lithium silicate (ZLS) is utilized as a material for prosthetic tooth crowns, offering enhanced strength compared to other dental glass-ceramics. In this study, we investigate a commercial ZLS material, provided in a fully crystallized form. We examine the effects of an optional post-processing heat treatment on micro-contact damage using controlled indentation tests simulating the primary modes of contact during chewing: axial and sliding. Our findings indicate that the heat treatment does not affect mechanical properties such as the elastic modulus, hardness and indentation fracture toughness. However, it does enhance the resistance to contact damage by fracture and chipping in both axial and sliding modes, as well as the resistance to crack initiation measured from sliding tests. This improvement is attributed to the refinement of the flaw population achieved through the heat treatment. The results are analysed using principles of contact and fracture mechanics theory, discussing their significance in prosthetic dentistry.

Comparisons of Two Different Treatment Methods for Impacted Maxillary Canines: A Retrospective Study.

Background: The impaction of the maxillary canine is a common occurrence, and orthodontists must be prepared to manage it. The purpose of this article is to present a study of the efficacy of a double-wire orthodontic appliance compared to a control group in the alignment of impacted maxillary canines in the dental arch. Methods: To diagnose an impacted maxillary canine, a panoramic radiograph was taken and a detailed analysis was performed by the same orthodontist. This article presents the results of 28 impacted maxillary canines with inclusion criteria of A2 (tooth angulation to the midline 16°-45°), V1 (vertical height of the tooth crown above the cementoenamel junction but less than half the length of the root of the maxillary lateral incisor), and O3 (medial position of the canine crown of more than half but less than the entire root width of the lateral incisor) positions in 21 patients (7 males and 14 females) with a mean age of 14.02 years (SD = 1.61) who were treated by the same orthodontist for impacted maxillary canines using a fixed double-wire orthodontic appliance. The analyzed data were compared with the control group (treated with a fixed orthodontic appliance and active ligature), which was matched for pretreatment age and the A2, V1, and O3 positions of the impacted maxillary canine. Results: With both methods, the impacted maxillary canines were aligned and guided into a correct position in the dental arch, but the mean active orthodontic traction of 31 ± 4.2 weeks in the SG was statistically significantly shorter (p < 0.05) in comparison to 37 ± 6.3 weeks in the CG, and the number of visits was statistically significantly (p < 0.05) fewer in the SG (5 ± 2) than in the CG (11 ± 5). Conclusions: The findings of this study are important to the field of orthodontics and show that the alignment of impacted maxillary canines with A2, V1, and O3 positions can be achieved with both methods, but with the double-wire appliance, the treatment time was shorter and the number of visits was statistically significantly fewer. The results of this study suggest that this approach may be more efficient and cost-effective compared to conventional methods.

Comparison of the Shear Bond Strength of Compomer Bonding on Different Enamel Surface Preparations

Objectives: To compare the effects of etching time and bonding agent application on the shear bond strength of compomer bonding in orthodontic bite raising. Methods: Seventy-five sectioned crown of maxillary premolar teeth were embedded in acrylic rings. The samples were divided into 5 groups according to enamel surface preparation before applying Ultra Band-Lok® (Reliance Orthodontic Products). Group 1: without surface preparation, Group 2: etched with 37% phosphoric acid (Kerr Gel Etchant, Kerr®) for 15 seconds, Group 3: etched with 37% phosphoric acid for 15 seconds, then apply bonding (OptiBond™ FL), Group 4: etched with 37% phosphoric acid for 30 seconds and Group 5: etched with 37% phosphoric acid for 30 seconds, then apply bonding. All samples were put through the thermocycling procedure and then shear bond strength was tested using the Universal Testing Machine. The mean and standard deviation of shear bond strength were statistically analyzed with two-way ANOVA and the enamel surface was observed by scanning electron microscope at 10,000x magnifications. Result: In Group 1, all Ultra Band-Lok® dislodged from the enamel surface during the thermocycling process. Consequently, shear bond strength testing could not be conducted for Group 1. The mean shear bond strength of Groups 2-5 were 19.80±7.06, 18.97±4.60, 18.04±5.09 and 16.80±5.47 MPa respectively. The mean shear bond strength of each group was not statistically significant difference (p=0.887). Conclusions: Varying enamel etching times (15 and 30 seconds) did not affect the compomer shear bond strength. Furthermore, the application of a bonding agent during tooth surface preparation did not significantly improve the bond strength between the compomer and the tooth surface.

Bayesian modeling of spatially differentiated multivariate enamel defects of the children’s primary maxillary central incisor teeth

BackgroundThe analysis of dental caries has been a major focus of recent work on modeling dental defect data. While a dental caries focus is of major importance in dental research, the examination of developmental defects which could also contribute at an early stage of dental caries formation, is also of potential interest. This paper proposes a set of methods which address the appearance of different combinations of defects across different tooth regions. In our modeling we assess the linkages between tooth region development and both the type of defect and associations with etiological predictors of the defects which could be influential at different times during the tooth crown development.MethodsWe develop different hierarchical model formulations under the Bayesian paradigm to assess exposures during primary central incisor (PMCI) tooth development and PMCI defects. We evaluate the Bayesian hierarchical models under various simulation scenarios to compare their performance with both simulated dental defect data and real data from a motivating application.ResultsThe proposed model provides inference on identifying a subset of etiological predictors of an individual defect accounting for the correlation between tooth regions and on identifying a subset of etiological predictors for the joint effect of defects. Furthermore, the model provides inference on the correlation between the regions of the teeth as well as between the joint effect of the developmental enamel defects and dental caries. Simulation results show that the proposed model consistently yields steady inferences in identifying etiological biomarkers associated with the outcome of localized developmental enamel defects and dental caries under varying simulation scenarios as deemed by small mean square error (MSE) when comparing the simulation results to real application results.ConclusionWe evaluate the proposed model under varying simulation scenarios to develop a model for multivariate dental defects and dental caries assuming a flexible covariance structure that can handle regional and joint effects. The proposed model shed new light on methods for capturing inclusive predictors in different multivariate joint models under the same covariance structure and provides a natural extension to a nested hierarchical model.

Computed Tomographic Findings of Dental Disease and Secondary Diseases of the Head Area in Client-Owned Domestic Rabbits (Oryctolagus cuniculus): 90 Cases.

Domestic rabbits have teeth that grow throughout the animal's life and are prone to disease. Clinical signs of dental disease in domestic rabbits are non-specific, and, therefore, a definitive diagnosis usually requires additional methods. This study was carried out on a group of 105 domestic rabbits aged 3 to 9 years. In total, 90 domestic rabbits with dental disease visible on CT images and other secondary diseases of the head area qualified for this study. Malocclusion was found in 57 (63.3%). Retrograde elongation of the tooth apices in the mandible was present in 39 (43.3%), and it was present in the maxilla in 48 (53%). Clinical tooth crowns were overgrown in 39 (43%). Dental abscesses were present in 54 (63%). Secondary to the presence of a dental abscess, osteomyelitis was found in 43 (79% of the animals with a dental abscess). Dental inflammatory resorption was found in 36 (40%). Secondary to dental disease, nasal cavity inflammation was found in 18 (20%). Otitis media was present in six (6.7%). The most common dental disease found in this study's animals was malocclusion secondary to abnormal clinical crown abrasion and abnormal tooth growth. In domestic rabbits, osteomyelitis is a common complication of dental abscesses. Computed tomography is an invaluable diagnostic method in the diagnosis of dental disease and secondary diseases of the head area, such as inflammation of the nasal cavities or otitis media, in pet rabbits.

New dinosaur remains increase theropod diversity in the Cañadón Asfalto Formation (Lower Jurassic), Chubut Province, Argentina

The Jurassic record of South American theropods is scarce, being represented by only seven nominal species. Four of these species (Eoabelisaurus mefi, Asfaltovenator vialidadi, Condorraptor currumili and Piatnitzkysaurus floresi) have been found in Toarcian-aged localities in the Cañadón Asfalto Formation (Chubut Province, Argentina) and, as a result, this unit has the highest known diversity of Jurassic theropods on the continent. A dentary with teeth in situ (MPEF-PV 6775) was found close to the base of this formation and differs from the other species from the unit with overlapping morphology. MPEF-PV 6775 resembles the dentary of the Late Jurassic North American theropod Ceratosaurus in being a robust bone, with a strong dorsal curvature in lateral view, and having relatively tall tooth crowns. MPEF-PV 6775 was scored in two matrices that have a broad taxonomic sample focused on Theropoda and the new specimen was recovered in large polytomies with other early neotheropods. A third analysis was conducted scoring MPEF-PV 6775 into a matrix focused in ceratosaurs because of its morphological similarities to Ceratosaurus. In this analysis, MPEF-PV 6775 was recovered as the sister taxon to Ceratosaurus, sharing with the later a ventral margin of the dentary that is strongly convex anteroposteriorly. These results suggest that MPEF-PV 6775 is a ceratosaurian and probably a ceratosaurid. Thus, our results indicate a higher taxonomic diversity of theropods and, in particular, ceratosaurs in the Cañadón Asfalto Formation. MPEF-PV 6775 seems to provide more evidence for the presence of ceratosaurids in the Jurassic of South America, together with isolated teeth described from the Late Jurassic of Uruguay and some analyses that recovered Eoabelisaurus and Berberosaurus within this clade.