Cheek Teeth Research Articles

First report on rhinoceros from the late Neogene Qin Basin of Shanxi, China

Dihoplus is a rhinoceros distributed across East Asia and Europe from the Late Miocene to Pliocene. This study describes a new skull from the Qin Basin in Shanxi Province, China, referred to as Dihoplus ringstroemi, which has long been debated in taxonomic identity. This skull confirms that D. ringstroemi is an independent species and reveals the presence of the upper incisor and variations in the degree of constriction of the two lingual cusps of upper cheek teeth. In addition, the new skull indicates that the Qin Basin has a late Neogene sediment and fauna comparable to that of the Yushe Basin.

The Discovery of Diadectomorph Tetrapods in the Lower Permian of Eastern Europe

The systematic position of the bolosaurid Stephanospondylus (Bolosaurus) traati (Tatarinov, 1974) is reassigned to the family Diadectidae (Diadectomorpha). This taxon is the first diadectomorph described from the Eastern Europe. Simple shape of the cheek teeth, as well as the pattern of the tooth differentiation along the maxilla indicate the basal position of S. traati within Diadectomorpha and its primitiveness in comparison with the type species to the genus Stephanospondylus, S. pugnax. The genus Ambedus Kissel et Reisz, 2004 is excluded from the order Diadectomorpha basing on the discrepancy of its marginal dentition to that of the other species of the group. The similarity of the dental system of Ambedus and diadectids is regarded as convergent rather than being due to its phylogenetic position, thus, the systematic position of this genus remains uncertain. The early stages of specialization of the dental system in the evolution of the family Diadectidae are discussed.

Dental Disease in Rabbits (Oryctolagus cuniculus) and Its Risk Factors-A Private Practice Study in the Metropolitan Region of Chile.

Rabbits (Oryctolagus cuniculus) have elodont dentition, a characteristic that predisposes them to the development of Acquired Dental Disease (ADD), which is a multifactorial disease. The aim of this study was to assess the risk factors for ADD in domestic pet rabbits. To do this, a retrospective analysis of 1420 rabbits treated at a private practice during 2018-2021 was performed. For this, several variables were retrieved from clinical records, in addition to signology at the time of diagnosis. ADD was found on 25.4% of rabbits, mostly on their cheek teeth. In addition, age (OR = 1.029; 95% CI = 1.023-1.035; p < 0.001) and sex (male) (OR = 1.591; 95% CI = 1.226-2.064; p < 0.001) were found to be significant risk factors for ADD. In contrast, a free lifestyle (OR = 0.565; 95% CI = 0.362-0.882; p = 0.012) and consuming hay in the diet (OR = 0.323; 95% CI = 0.220-0.473; p < 0.001) were protective factors. In conclusion, ADD has a high prevalence and is usually underdiagnosed, highlighting the need for an exhaustive evaluation of patients during the clinical examination. This study improves our knowledge of ADD and its prevention.

Behavioral Signs Associated With Equine Cheek Tooth Findings.

Equine dental diseases are often underdiagnosed and their signs inadequately reported. Many horse owners have difficulties in recognizing pain-related behavioral signs and in associating them with dental pain. Our objective was to determine what type and degree of dental findings may cause behavioral signs associated with dental pain. In this cross-sectional study, dental examination was performed on 183 adult horses and cheek tooth findings were scored. Owners filled in an internet-based questionnaire including 35 questions concerning eating behavior, bit behavior, and general behavior of the horse. Descriptive statistics and logistic regression analyses were performed. Broadened or darkened fissures [odds ratio (OR) 2.4, 95% confidence interval (CI) 1.04-5.7), complicated fractures (OR 2.3, CI 1.01-5.2) and secondary dentine defects of at least the second degree (OR 3.1, CI 1.2-7.7) were associated with the expression of at least five behavioral signs in the univariable binomial logistic regression analyses. Horses with at least one of these potentially painful cheek tooth findings expressed more signs related to eating behavior, bit behavior, and general behavior than did the other horses. The results suggest that cheek tooth findings indicated by this study as being potentially painful, i.e. broadened or darkened fissures, complicated fractures and secondary dentine defects of at least the second degree, may require intervention, particularly if the horse expresses any behavioral signs that might be related to dental pain.

Estimates of absolute crown strength and bite force in the lower postcanine dentition of Gigantopithecus blacki

Gigantopithecus blacki is hypothesized to have been capable of processing mechanically challenging foods, which likely required this species to have high dental resistance to fracture and/or large bite force. To test this hypothesis, we used two recently developed approaches to estimate absolute crown strength and bite force of the lower postcanine dentition. Sixteen Gigantopithecus mandibular permanent cheek teeth were scanned by micro-computed tomography. From virtual mesial cross-sections, we measured average enamel thickness and bi-cervical diameter to estimate absolute crown strength, and cuspal enamel thickness and dentine horn angle to estimate bite force. We compared G. blacki with a sample of extant great apes (Pan, Pongo, and Gorilla) and australopiths (Australopithecus anamensis, Australopithecus afarensis, Australopithecus africanus, Paranthropus robustus, and Paranthropus boisei). We also evaluated statistical differences in absolute crown strength and bite force between the premolars and molars for G. blacki. Results reveal that molar crown strength is absolutely greater, and molar bite force absolutely higher, in G. blacki than all other taxa except P. boisei, suggesting that G. blacki molars have exceptionally high resistance to fracture and the ability to generate exceptionally high bite force. In addition, G. blacki premolars have comparable absolute crown strength and larger bite force capabilities compared with its molars, implying possible functional specializations in premolars. The dental specialization of G. blacki could thus represent an adaptation to further facilitate the processing of mechanically challenging foods. While it is currently not possible to determine which types of foods were actually consumed by G. blacki through this study, direct evidence (e.g. dental chipping and microwear) left by the foods eaten by G. blacki could potentially lead to greater insights into its dietary ecology.

Histological characteristics of macrodontic cheek teeth of guinea pigs

Macrodontia is the enlargement of tooth dimensions of different ethologies. This work aims to show a histological evaluation of macrodontic teeth in guinea pigs. The material was obtained from animals postmortem. Ninety structural changes derived from 24 guinea pigs were evaluated. All teeth used in the study showed macrodontic changes. The samples were decalcified, dehydrated and embedded in paraffin. Material was cut in the transverse and longitudinal planes in relation to the alveolar bone. Histological evaluation included apical bud cells, pulp cavity cells, periodontium, dentin, enamel, cementum and alveolar bone tissue. Individual elements were evaluated with respect to their morphology and distribution. Moreover, the arrangement of the individual hard tooth structures was assessed on the teeth. No atypia was found among the cells that make up the apical bud, pulp or periodontal cavity. Displacement of periodontal cells or odontoblasts towards the pulp cavity as well as disorganization of the cell system in the pulp cavity were observed. Changes in the dentine ligaments and the reconstruction of the alveolar bone were also observed in areas where dentine and cement systems were affected. Dental slides were observed and showed that the enamel is also involved in structural remodelling of the pulp cavity. The histological assessment revealed that structural changes in macrodontic teeth involve the rearrangement of typical tooth tissues.

Avoiding the lockdown: Morphological facilitation of transversal chewing movements in mammals.

The evolution of mammals is characterized, amongst other developments, by an increasing relevance of effective food processing in form of an increasingly durable dentition, complex occlusal surfaces, and transverse chewing movements. Some factors have received increasing attention for the facilitation of the latter, such as the configuration of the jaw joint, the chewing muscle arrangement and lever arms, or the reduction of interlocking cusps on the cheek teeth occlusal surface. By contrast, the constraining effect of the anterior dentition (incisors and canines) on transverse chewing motions, though known, has received less comprehensive attention. Here, we give examples of this constraint in extant mammals and outline a variety of morphological solutions to this constraint, including a reduction of the anterior dentition, special arrangements of canines and incisors, the nesting of the mandibular cheek teeth within the maxillary ones, and the use of different jaw positions for different dental functions (cropping vs. grinding). We suggest that hypselodont anterior canines or incisors in some taxa might represent a compensatory mechanism for self-induced wear during a grinding chewing motion. We propose that the diversity in anterior dentition among mammalian herbivores, and the evolutionary trend towards a reduction of the anterior dentition in many taxa, indicates that the constraining effect of the anterior dentition, which is rigidly linked to the cheek teeth by the osseous jaws, represents a relevant selective pressure in mammalian evolution.

Standing equine cheek tooth extraction: A multivariate analysis of the effect of antibiotics on the risk of post-operative complications.

Commonly, cheek tooth extraction performed in standing horses using perioperative prophylactic antibiotics, results in low post-operative complication rates. However, no studies have documented the relevance of perioperative antibiotics to the risk of post-operative complications. To examine the association between perioperative antibiotics and post-operative complications after standing cheek tooth extraction. Retrospective cohort study. Information from clinical records and follow-up questionnaires relating to horses subjected to cheek tooth extractions between September 2016 and May 2020 was obtained. Post-operative complications and associations with perioperative antibiotics, age, sex, breed, diagnosis, tooth position, and extraction method were analysed using multivariate logistic regression. A total of 305 horses were included, and of these 71 (23.3%) received perioperative antibiotics. Antibiotics were not associated with the risk of complications in 264 horses that underwent standard oral extraction; 9/49 (18.4%) that received antibiotics and 35/215 (16.3%) that did not receive antibiotics experienced postoperative complications (P =1, RR=0.89, OR=1, OR CI=[0.41; 2.46]). Of 41 horses that had cheek tooth extraction through minimally invasive transbuccal cheek tooth extraction (MTE), 5/22 (22.7%) that received antibiotics and 10/19 (52.6%) that did not receive antibiotics, experienced postoperative complications. Although not statistically significant when adjusting for multiple comparisons (naïve P =0.04, adjusted P =0.26, RR=2.32, OR=4.48, OR CI=[1.05; 19.11]), this finding is clinically relevant. Younger age was also significantly associated with development of complications (P =0.02, OR=0.92 per year, OR CI=[0.87; 1.36]). The retrospective nature of the study leads to uncontrollable potential confounders and there is a relatively low number of MTE cases. Perioperative antibiotics were not associated with a lower complication rate in horses subjected to standard standing cheek tooth extraction. Use of perioperative antibiotics in conjunction with MTE may be merited, although further investigations are needed.

Doenças periodontais e desgaste dentário em rebanhos ovinos no Estado de Goiás, Brasil

ABSTRACT: Dental and periodontal affections consist of health concerns of great importance in sheep flocks, as they affect the health and welfare of animals and represent one of the main causes of premature slaughter. Studies on the occurrence of these conditions in sheep are scarce in Brazil. The present study aimed to evaluate the prevalence of periodontal diseases and tooth wear in sheep flocks in the State of Goiás. For this, a clinical oral examination was conducted on 325 sheep from seven farms in six municipalities of the State. Periodontal lesions, characterized by gingival recession in at least one incisor tooth, were observed in 48.3% (157/325) of the sheep, while in cheek teeth it occurred in 13.2% (43/325) of the evaluated sheep. Dental wear on cheek teeth was identified in 69.2% (255/325) of the sheep, and 10.7% (35/325) of the ovines showed dental wear on incisor teeth. Sheep older than 36 months had an increase in the frequency of tooth wear. A total of 171 (52.62%) out of the 325 examined sheep had signs of bleeding on probing, which is compatible with gingivitis, and 69 (40.36%) were older than 36 months. Thirty-eight (11.69%) out of the 325 evaluated ovines had gingivitis in all teeth, among which 21 (55.26%) were older than 36 months. Logistic regression analysis allowed the observation that age was associated with the occurrence of gingivitis. Less frequent changes such as periodontal pockets and loss of at least one tooth were also observed in 4.9% (16/325) and 17.8% (58/325) of the sheep, respectively. It indicates that the presence of periodontal diseases and tooth wear is a common occurrence in the evaluated flocks. Therefore, there is a need to include the oral health of sheep in the routine of the farm as an essential preventive measure to improve the quality of life, animal welfare, and zootechnical indices.

Dental and oral cavity alterations in Quarter Horses of Vaquejada: retrospective study of 416 cases (2012-2022).

Oral and dental diseases are common in horses, as evidenced by the results of incidence studies of dental diseases carried out on abattoir specimens or sports horses. Thus, periodic dental examinations in horses are essential to ensure the maintenance of dental health and proper use of ingested food. A retrospective study of the dental records of 416 Quarter Horses (256 males, 160 females), distributed in the western region of the Rio Grande do Norte, Brazil, was conducted. Horses were examined between July 2012 and August 2022. The variables collected were age, sex, type of diet, dental alterations identified, and history of colic in the last 365 days. The animals were divided into three groups according to age: group I (2 to 6 years old), group II (7to12 years old), and group III (13to 24 years old). Pairwise comparisons were performed using Tukey's correction. The most frequent dental alterations were excessive tip of the tooth enamel, limited/asymmetric lateral excussion, oral ulceration, eruption of the first premolar tooth, and rostral hook. Statistical differences (p<0.05) were observed between the age groups in the following alterations: excessive tip of the tooth enamel, limited/asymmetric lateral excussion, eruption of the first premolar tooth, rostral hook, palatitis, step, caudal hook, retention of deciduous cheek teeth, wave, tartarus, underbite, periodontal disease, and incisors of the dorsal curve. Dental disorders in horses are of major clinical importance.

Microscopic examination of the horse teeth and their surrounding tissues. Part II: Histology of the cheek teeth

Microscopic examination of the horse teeth and their surrounding tissues. Part II: Histology of the cheek teeth

Complications after surgical extraction of cheek teeth in horses

The aim of this article is to summarise the factors that influence the occurrence of complications after surgical extraction of teeth in horses. This is influenced not only by the choice of method, but also by the age of the horse, the position of the tooth, the experience of the person performing the procedure and the available diagnostics methods. It should be emphasised that the procedure is performed only when there is no possibility of further conservative treatment and an increasing clinical condition may be an important risk factor for complications. Further studies focusing on the topic are needed to fully assess the number of complications and the links between their occurrence and the relevant factor.

New Material of Leptictids (Mammalia: Leptictida) from the Late Eocene (Duchesnean–Chadronian) of Southwestern Montana

Previously unreported material of leptictids (Mammalia: Leptictida) is described from three latest Eocene localities in Montana: Pipestone Springs (Ch3), McCarty's Mountain (Ch2), and Diamond O Ranch (Du–Ch1). Additional and more complete specimens of Leptictis acutidens (Douglass, 1901) from its type locality are also described. The first specimens of Leptictis intermedius (Douglass, 1905) outside of the type locality of McCarty's Mountain are described from the Diamond O Ranch fauna. Although previously suggested as a synonym of Leptictis montanus (Douglas, 1905), L. intermedius is recognized as a distinct species based on its smaller size, cranial features (narrower zygomatic arch, single squamosal sinus canal, large suprameatal foramen), and dental features (paraconule transversely elongated and more lingual than metaconule on P5–M3; and metacone moderately to well developed on M3). Leptictis thomsoni (Matthew, 1903) is referred to a new genus, Stenoleptictis based on previously undescribed lower dentitions and crania from both Pipestone Springs (type locality) and McCarty's Mountain. The most diagnostic characters of Stenolepticis thomsoni (Matthew, 1903), new combination, are the lingually narrower upper cheek teeth with reduced anterior cingula and the presence of more lateral, lyrate parasagittal crests on the cranium, features unreported in any other leptictids.

Complications of equine cheek teeth extractions

SummaryDue to the length of the reserve crown and roots of equine cheek teeth, especially in young horses, their extraction (exodontia) can be a challenging procedure with the potential for many types of post‐extraction complications to develop. The prevalence of post‐extraction complications is greatly influenced by the exodontia technique used, with unacceptably high levels of complications with the traditional repulsion technique and conversely, low levels of complications with oral extraction performed by skilled operators. Recent objective studies on post‐exodontia problems in horses have also highlighted some risk factors for the development of post‐extraction problems including exodontia of rostral mandibular teeth in young horses, and exodontia of teeth with apical infections. The recent recognition that some nonhealing post‐extraction equine alveoli suffer from a disorder very similar to dry socket in humans, may help clinicians to recognise, treat and possibly help prevent this disorder.

Sex‐specific impact of tooth wear on senescence in a low‐dimorphic mammal species: The European roe deer (Capreolus capreolus)

AbstractAmong ungulates, capital breeding males, especially in highly dimorphic species, support higher reproductive costs than females. Roe deer, a relatively monomorphic species, is defined as an ‘income breeder’, using a concurrent intake of energy from forage to pay for a reproductive attempt. In a Northern Apennines (Arezzo province, Tuscany, Central Italy) population, we detected sexual dimorphism in adult roe deer according to average body mass (males 11% heavier than females), mandible size (male mandibles are 2% longer than female ones), and tooth measurements (first lower molar 10% higher and mandible cheek teeth row 4% longer in males than in females, providing males with a larger surface for chewing). In our study, body mass and body condition of roe deer males decreased with increasing tooth wear as in females. However, males started losing weight at a lower tooth wear level than females; after losing about 15% (~3.2 kg) of body mass they had greater probability of death than females. For low‐dimorphic species like roe deer, these findings raise new considerations about the role of sexual dimorphism in feed intake efficiency.

Ancestral radiation of paenungulate mammals (Paenungulatomorpha)—new evidence from the Paleocene of Morocco

ABSTRACT Reported here is the discovery of a new mammal from the middle Paleocene of the Ouled Abdoun phosphate basin, Morocco. Hadrogeneios phosphaticus, gen. et sp. nov., is described based on dental and gnathic specimens. Comparative dental anatomy and CT scan observations support stem relationships to paenungulates. The cladistic analysis relates Hadrogeneios to paenungulatomorphs, especially based on the shared morphotypic condition of a dilambdodont ectoloph linked to inflated stylar cusps. Within the Paenungulatomorpha, Hadrogeneios is plesiomorphic not only with respect to crown paenungulates, but also to Abdounodus and Ocepeia, making it the basalmost known paenungulatomorph. Hadrogeneios, on the other hand, displays a peculiarly specialized mandibular symphyseal region (mentum), which is enlarged and raised high above the cheek teeth, and bears at its apex small incisors that are innervated and vascularized by a peculiar long and thin dorsal canaliculus. This is tentatively interpreted as a plier-like dental apparatus specialized for enhanced oral gripping function of the food, with increasing grip strength or enhanced grip precision. A composite reconstruction of the lower jaw of Hadrogeneios phosphaticus, based on 3D modeling from CT scans, is provided. Hadrogeneios, Abdounodus, and Ocepeia, all from the same Ouled Abdoun Paleocene phosphate levels, are the very rare witnesses of the first evolution and diversification of the endemic African ungulates phylogenetically preceding the modern paenungulate orders.

Systematic palaeontology of late Miocene lagomorphs from the Aït Kandoula Basin (Morocco)

The occurrence of the genus Prolagus Pomel, 1853, in North Africa provides some of the strongest evidence for the existence of faunal exchanges between Europe and Africa. The oldest African Prolagus remains have been reported from the Messinian locality of Afoud in the Aït Kandoula Basin (6.2 Ma), identified during previous studies as the species Prolagus michauxi López-Martínez, 1975. Dental material already analyzed from the AF12-1 and AF12-2 levels and new material collected subsequently from the same levels form the basis of the current systematic study. This abundant material allows us to confirm the presence of a single Prolagus species in the Afoud locality, P. michauxi. However, this species’ attribution to P. michauxi must be considered cautiously, given its evident morphological resemblance to Prolagus sorbinii Masini, 1989. These results are consistent with scenarios implying the migration of P. michauxi from Southern Europe to North Africa. In addition to the Prolagus remains, cheek teeth of Leporidae have been found and this is the oldest occurrence of this group in Morocco.

Malocclusions and Dental Diseases in Privately Owned Horses in the Mazovia Region of Poland.

Dental disorders, a term encompassing both malocclusion and dental disease, constitute a serious health problem in horses worldwide. As horse populations differ among countries and regions, a geographically specific characterization of the occurrence of various dental disorders may be helpful for local equine practitioners. This study investigated the prevalence and frequency distribution of selected malocclusions and dental diseases in horses housed in the Mazovia region of Poland, with attention paid to variations among age, gender, and breed categories. Routine dental examinations were conducted on 206 privately owned horses (n = 206). Disorders were recorded using a dental chart and classified as either malocclusions or dental diseases. Out of all examined horses, 95% demonstrated at least one dental disorder, with a roughly equal distribution of these disorders among incisor teeth (31%) and cheek teeth (31% each for premolars and molars). More specifically, there were disorders noted in 14 incisors, 3 canines, 2 wolf teeth, and 15 cheek teeth. Across all age, gender, and breed groups, malocclusions of incisor, premolar, and molar teeth occurred with a higher prevalence than did dental diseases. Curvatures and calculus were the most commonly reported pathologies in incisor teeth, whereas sharp enamel points and caries predominated in cheek teeth.

A clinical survey of 244 equines with dental disorders in Thailand

Dental problems in equines can cause emaciation, colic, and poor performance. Types of dental disease in equine populations have been reported worldwide in veterinary medicine; however, few detailed investigations of equine dental problems in Thailand have been published. Thus, this study aimed to determine the prevalence of equine dental problems in Thailand. Standard dental and oral cavity examinations were performed on 244 equines (232 horses and 12 donkeys) ranging in age from 2–21 years (median = 9.88) from Western, Northern, and Central parts of Thailand between January 2015 and December 2017. The dental disorders were recorded and the data was analyzed to determine the proportion as a percentage of dental disorders. Logistic regression was used to find relations between dental floatation routine, gender, age, body weight, and dental disorders. The survey showed that sharp cheek teeth (82.37%) was the most common problem, which was often associated with frontal hook (10.65%) and caudal hook (6.55%). Other disorders observed included incisor tartar (9.42%) and canine teeth tartar (9.42%). One to two years routine of dental examination and floatation has 2.54 times (p&lt;0.01) higher chance to develop sharp teeth compared to 0.5-1 year routine. In addition, not having any routine increased this effect by 22 times(p&lt;0.01). Sharp cheek teeth was by far the most found and significant dental problem in these equines. These findings show the importance of regular dental floating and tartar scaling. Early detection and treatment can improve equine oral health.

A new Late Miocene hystricognath rodent assemblage (Caviidae, Dinomyidae, and Neoepiblemidae) from northern Brazil and its biostratigraphic relevance

ABSTRACT The Neogene strata of the Solimões Formation (northern Brazil) have revealed an astonishing diversity of extinct caviomorph rodents. The main exposures of this formation are found along the Juruá, Acre, and Purus rivers, and some road cuts in the State of Acre. In this paper, we reported a new locality containing a rodent assemblage. The outcrop (Coqueiro locality) is located in the Envira River, central region of State of Acre, Brazil. During fieldwork in 2010 and 2019, several isolated cheek teeth and bones of mammals were recovered in conglomeratic levels from this locality. Here, we described specimens assigned to Cardiatherium sp. (Caviidae: Hydrochoerinae), Potamarchus sp. and cf. Pseudopotamarchus (Dinomyidae: Potamarchinae), and Neoepiblema sp. (Neoepiblemidae). The locality is not yet dated by radiometric methods but based on the biostratigraphic information of the taxa here reported, we suggest that the fossil-bearing levels of this locality were deposited during the Late Miocene.