Mandibular Morphology Research Articles

Impact of mandibular overdentures on maxillary resorption and its association with masticatory function: A prospective longitudinal study with 3 years of follow-up.

This longitudinal clinical study monitored annually the maxillary and mandibular bone remodeling and masticatory function in complete denture (CD) wearers rehabilitated with implant-retained mandibular overdentures (MO) over three years and combined radiographic and masticatory function data to assess the correlation between bone remodeling and masticatory function. Thirty-nine MO wearers were monitored annually to assess changes in: i) residual ridge in the anterior and posterior maxillary region; ii) posterior height and posterior area index (PAI) in the mandible; and iii) masticatory function. Bone remodeling was measured through linear and angular measurements using panoramic radiographs. Masticatory function was evaluated by swallowing threshold test, to determine the median particle size (X50) and homogenization index (B). A mixed-effects multilevel regression model estimated differences between radiological and masticatory parameters over time, with associations verified using Pearson's correlation test. Significant changes in mandibular bone variables (PAI and L1/R1, L2/R2, L3/R3; p ≤ 0.01) occurred when transitioning from CD to MO, showing a reduction in PAI values and slight reduction in mandibular linear measurements. Improvements in masticatory parameters were also observed, highlighting the benefits of transitioning to MO. Over three years of MO usage, significant changes in all radiographic bone parameters were found, with increased PAI and maxillary bone values in the first year. The correlations between masticatory function and radiological parameters indicated that mandibular morphology can significantly influence masticatory function especially in patients wearing CDs. Following the transition to MO, only one consistent significant correlation was observed between X50 and R3/L3 at the 1-year and 3-year intervals. Continuous changes in bone parameters were observed in MO wearers, with stabilization of maxillary ridge resorption and ongoing mandibular remodeling, alongside slight changes in masticatory function, suggesting transitory correlations between linear changes in the posterior region of mandible and masticatory function over time.

Morphometric Study on the Mandible of Colobine Fossil (Mesopithecus pentelicus) Found in East Asia, a Comparison With Extant Taxa.

A tooth-bearing mandible fossil of a colobine monkey discovered at Shuitangba, Zhaotong, Yunnan, China, was morphometrically analyzed and compared with extant Asian colobines. Our previous qualitative and quantitative descriptions indicate that it can be safely attributed to Mesopithecus pentelicus, a Miocene fossil colobine widely found in Europe and South Asia. The present research aims to explore fossil association with extant colobines and functionally propose its dietary preferences based on multivariate morphometric analyses of mandibular morphology. The results indicate that this fossil species presents a mosaic association with extant langurs (Presbytis, Trachypithecus, and Semnopithecus) and odd-nosed monkeys (Pygathrix, Nasalis, and Rhinopithecus), with most similarities of size-related traits and size-adjusted shapes, and a notable difference from extant Rhinopithecus, due to the increased body size of the latter since the Pliocene. The allometric analysis showed that, like the fossils of the same species in other sites, its mandibular structure appears more adapted to crushing hard seed shells than chewing leaves. Moreover, our findings also imply that the Asian colobines significantly modified their dietary preferences over the last 6 million years following the ecological and environmental changes triggered by the accelerated uplift of the Qinghai-Tibet Plateaus and severe monsoons. Morphologically, the more developed condyle length and moment arms of the temporomandibular joint and medial pterygoid muscles appear to accommodate a more folivorous dietary selection, functionally related to the intake of rigid fibers in leaves that require frequent one or two-side mandibular chewing and grinding.

An evaluation and correlation of airway space of pharynx, mandibular morphology, and tongue volume in skeletal classes and facial patterns – A cone beam computed tomography study

Objectives: Respiration and its function have a direct relationship with the pharyngeal airway, mandibular morphology, and tongue. The objective of this study was to evaluate and correlate pharyngeal airway space, mandibular morphology, and tongue volume in various skeletal classes and facial patterns. Material and Methods: A total of 120 pre-treatment cone beam computed tomography (CBCT) images were randomly classified into 3 skeletal classes (40/group). Each class was further categorized into hyperdivergent and hypodivergent growth patterns. Linear and angular measurements were estimated using three-dimensional digital imaging programs (Kavo 3D OnDemand software), and pharyngeal airway and tongue space were volumetrically analyzed by ITK-SNAP segmentation software. Results: All the measured variables showed highly significant differences except for the anterior-posterior angle of the mandible, which was statistically insignificant with P = 0.675. The simple regression was formulated to assess the volume of airway space. Conclusion: Hyperdivergent subjects had reduced pharyngeal airway space and tongue volume when compared to hypodivergent subjects. Among all the subgroups, Class III hypodivergent showed the highest pharyngeal airway volume and tongue volume, and the least was found in Class II hypodivergent. A direct relationship was estimated between airway mandibular morphology and tongue volume, recommending thorough analysis of oropharyngeal structures in a non-individualized way for orthodontic diagnosis and treatment planning.

Update on Current Knowledge of Paediatric Obstructive Sleep Apnoea: From Animal to Human Studies.

Orthodontists' interest in paediatric obstructive sleep apnoea (PedOSA) has grown in popularity recently. We have seen growth modification treatment modalities, including maxillary expansion, promising the prevention or cure of PedOSA. Clinical approaches such as palatal expansion and mandibular and maxillary complex advancement have been proposed to manage PedOSA. These hypotheses should be adequately tested before clinical recommendations are formulated. This review aimed to narratively synthesise our current understanding of PedOSA management with craniofacial growth modification alternatives. Basic research on the biological basis of PedOSA has been conducted in animal models. Laboratory-based PedOSA studies wish to provide insight into the molecular biological mechanisms by which human PedOSA affects growth-associated structural and emotional growth and development. In the proposed IH animal model, mandibular growth (especially posterior anteroposterior and transverse dimensions) and condylar head bone density were more sensitive to IH exposure in adolescents but less in juvenile rats. Nevertheless, clear-cut statistical growth differences were limited. This suggests that IH, in this rat model, influenced mandibular morphology and metabolism later than earlier craniofacial growth stages. No impact was found for the maxillofacial complex in any plane of space. The existing human studies on the causes, risk factors, consequences, symptomatology, diagnosis and effects of PedOSA are discussed. However, there is a pressing need for further research to clarify whether craniofacial disturbances are consequences or facilitators of PedOSA. Several hypotheses about the potential impact of impaired craniofacial growth as a facilitator for PedOSA currently circulate.

Functional Units Analysis of Mandibular Morphology in Patients With Parry-Romberg Syndrome.

To characterize mandibular morphology in patients with Parry-Romberg syndrome (PRS). Retrospective study. A craniofacial center. Thirty-three patients with PRS affecting mandible. Preoperative computed tomography data were analyzed using Mimics 26.0 (Materialise Inc.). Distances between landmarks-condyle process (Con), coronoid process (Cor), mandibular foramen (IAF), gonion (Go), and mental foramen-were measured to represent the sizes of skeletal units. Positional asymmetry was reflected by angles between lines connecting bilateral landmarks and the occlusal plane. Bilateral differences in unit sizes were compared. Absolute difference (Δ) > 5 mm and relative size (RS) < 80% were set to evaluate the severity of hypoplasia. Angular measurements were compared to 0° using one-sample t tests. Pearson correlation analysis was conducted to examine the relationship between onset ages and both RS and angular measurements. The affected side's skeletal units were smaller. Severe hypoplasia was more common in the angular unit. Angles between Con-Con', Cor-Cor', IAF-IAF', and the occlusal plane were less than 0°, whereas the angle with Go-Go' was greater than 0°. Age of onset was positively correlated with the condylar unit size and the Con-Con' to occlusal plane angle. Patients with PRS affecting mandible exhibit smaller skeletal units on the affected side, particularly in the angular unit. Most landmarks on affected side tend to cluster toward the occlusal plane. Earlier onset of PRS correlates with more pronounced condylar asymmetry. Evaluating the severity of functional units involvement and implementing appropriate treatment should be considered.

Mandible composition and properties in two selected praying mantises (Insecta, Mantodea).

Insects process their food with their cuticle-based mouthparts. These feeding structures reflect their diversity and can, in some cases, showcase adaptations in material composition, mechanical properties, and shape to suit their specific dietary preferences. To pave the way to deeply understand the interaction between mouthparts and food and to determine potential adaptations of the structures to the food, this study focuses on the mandibles of two praying mantis species. Gongylus gongylodes feeds mainly on Diptera, and Sphodromantis lineola forages on larger prey. Employing scanning electron microscopy, the mandibular morphologies were analyzed. The degree of the cuticle tanning was tested using confocal laser scanning microscopy. Furthermore, the contents of transition and alkaline earth metals in the mandible cuticle were studied using energy-dispersive X-ray spectroscopy and the mechanical properties tested by nanoindentation. We found that S. lineola mandibles show pronounced gradients of Young's modulus and hardness from the basis to the tip, which might be an adaptation against high stresses during biting and chewing. G. gongylodes, in contrast, did not show pronounced gradients, which may indicate that there is less stress involved in feeding-necessary to test in future studies. The mechanical properties of manidibles in both species are related to the degree of cuticle tanning but also positively correlate with the content of magnesium. These findings enrich our understanding of insect cuticle biology but also present new sets of data on praying mantis structures.

The dentary of Protolipterna ellipsodontoides: description, taxonomy, and palaeobiology

ABSTRACT Protolipterna ellipsodontoides is a small bunodont South American native ungulate, generally considered an early litoptern, exclusively found in the Palaeogene Itaboraí Basin. Its dentition is well known; however, its mandibular morphology was only known by fragmentary materials. Here, we describe the first complete mandible of this species. A micro-CT scan reveals the first case of alveolus resorption in this putative early litoptern. Two accessory canals on the retromolar region are also described. Canals on the retromolar region are documented for other mammalian orders; however, this represents the first description of this feature for the Protolipternidae. Unlike more advanced litopterns, this species lacks specialisations related to strict herbivory, and its dental and mandibular morphology suggests an omnivore habit. A comparison with the mandible of another Itaboraian protolipternid, Miguelsoria parayirunhor, indicates the presence of different dietary specialisations. Body mass estimations for both species are also provided.

Mandibular morphology in schizophrenia patients compared with non-psychiatric controls using digital panoramic radiography: a retrospective cross-sectional study from Istanbul, Türkiye

BackgroundSchizophrenia is a chronic severe mental disorder characterized by impairment in cognition, emotion, perception, and other aspects of behavior. In light of the association of craniofacial dysmorphology with schizophrenia, mandibular morphology may provide clues about the role of neurodevelopment in the pathophysiology of schizophrenia. This retrospective cross-sectional study aimed to compare the mandibular morphology of patients with schizophrenia with controls using digital panoramic radiography (DPR).Methods302 recorded diagnostic panoramic images obtained from 143 schizophrenia patients (98 males, 45 females), and 159 controls (73 males, 86 females), aged 18–45 years, were evaluated. Seven mandibular measurements consisting of ramus height, condylar height, gonial angle, antegonial angle, antegonial notch depth, ramal notch depth and bigonial width were measured from the DPRs in a double-blinded manner. Bivariate comparisons were carried out using the Independent t-test and Mann–Whitney U test. Logistic regression analysis was used for multivariate comparisons.ResultsLinear measurements were higher while angular measurements were lower in schizophrenia patients. Regression analyses indicated that female patients had greater ramus height (OR = 1.243; P = 0.001), condylar height (OR = 1.463; P = 0.048) and bigonial width (OR = 1.082; P < 0.001); male patients had greater ramus heights (OR = 1.216; P = 0.001) and bigonial width (OR = 1.076; P < 0.001) as well as lower antegonial angle (OR = 0.908; P = 0.012) compared to their respective controls.ConclusionQuantitative differences in mandibular morphology in schizophrenia patients versus controls deserve attention and corroborate with the concept of abnormal neurodevelopment in schizophrenia.

Determination of Mandibular Morphology in a Turkish Population With Bipolar I Disorder Using Panoramic Radiography.

The presence of specific craniofacial deviations may be evidence of abnormal early brain development in bipolar disorder (BD). This study aimed to compare mandibular morphology in patients with BD versus nonpsychiatric controls using panoramic radiography. A total of 215 recorded images, 70 patients with BD and 145 controls, were evaluated. Seven mandibular parameters of the ramus height (RH), condylar height (CH), gonial angle (GA), antegonial angle (AGA), antegonial notch depth (AND), ramal notch depth (RND), and bigonial width (BGW) were measured in a blinded manner. Group analysis was conducted separately for males and females. The univariate comparisons showed increased values in RH, CH, AND, RND, and BGW and decreased values in GA in males with BD compared with male controls. In addition, females with BD had higher RH, CH, RND, and BGW values in comparison to female controls. The differences were statistically significant. Data from multivariate analyses revealed that increases in RH and BGW values in both sexes were significant predictive variables that distinguished patients with BD from controls. Moreover, deeper AND was the most prominent predictor that distinguished male patients with BD from male controls. The identification of subtle changes in mandibular measurements is consistent with the notion of impaired neurodevelopment in BD.

MANDIBULAR PARAMETERS FOR AGE ESTIMATION: A DIGITAL ORTHOPANTOMOGRAPHIC STUDY IN HYDERABAD POPULATION

Background: Mandible is one of the strongest facial bones, which exhibits great changes in size and morphology during growth and aging. The mandibular ramus and gonial angle in particular show notable alterations with aging. Orthopantomographywhich is a regularly used, non-invasive procedure can be used to assess mandibular morphology with ease. Aim and objectives: To assess the correlation of dimensions of condylar ramus height, coronoid ramus height and gonial angle with chronological age of the individual, andevaluatetheirefficacy in estimating age of the individual. Materials and methods: The study sample included 200 digital orthopantomographs of individuals of diverse age groups. Measurements of condylar ramus height, coronoid ramus height and gonial angle were made on the digital orthopantomographs and data was tabulated. Age estimation formulae were derived for each of the three parameters and age was estimated for each individual using the formulae. Results: No statisticallysignificant difference was found on comparing the chronological age and estimated age obtained using condylar ramus height, coronoid ramus height, and gonial angle. Among the three parameters,coronoid ramus height displayed a statistically significant correlation with chronological age. Conclusion:Present study indicates that coronoid ramus height can be used as a reliable indicator for age estimation.

The mitochondrial genome of the critically endangered enigmatic Kazakhstani endemic Selevinia betpakdalaensis (Rodentia: Gliridae) and its phylogenetic relationships with other dormouse species

Dormice (family Gliridae) are an ancient group of rodents. It was fully dominant in the Oligocene and Early Miocene, and its current diversity is represented by a few extant species. A Kazakhstani endemic, the desert dormouse Selevinia betpakdalaensis is one of the most enigmatic dormouse species. Lack of genetic data has not allowed Selevinia to be included in previous molecular phylogenetic analyses. In the current study, we report the first genetic data on S. betpakdalaensis as well as mitochondrial genomes of Myomimus roachi and Glirulus japonicus (retrieved from museum specimens) and a mitogenome of Graphiurus murinus (assembled from SRA data). The assembled mitochondrial genomes were combined with available mitochondrial data from GenBank to reconstruct the mitochondrial phylogeny of Gliridae. Taking into account a distortion of the phylogeny as a result of an analysis of the saturated third codon position, we obtained for the first time a resolved phylogeny of the family. The first split within Gliridae was estimated as an average of 34.6 Mya, whereas divergence time of subfamilies Graphiurinae and Glirinae was assessed at 32.67 Mya. The phylogenetic analysis confirmed the relationship (previously shown based on cranial and mandibular morphology) between Selevinia and the Myomimus.

Morpho-Geometric Description of the Skulls and Mandibles of Brown Bears (Ursus arctos) from the Dancing Bear Belitsa Park.

The present study aimed to describe the skull and mandibles of the brown bear (U. arctos) from the Dancing Bear Belitsa Park using advanced 3D morpho-geometric techniques. The objective was to explore how sexual dimorphism and size influence cranial structures using advanced 3D geometric morphometric methods. Three-dimensional models of the skulls and mandibles of 12 brown bears were used. Differences in skull morphology between male and female brown bears were observed in this study. The male brown bear skull, larger than the female, exhibited a more pronounced extension of the upper part of the nuchal region towards the posterior. Additionally, the posterior part of the frontal region appeared notably thinner in male brown bears compared to females. Analysis of the mandible revealed that the masseteric fossa was more developed in males than females. These shape differences between males and females were found to be influenced by body size. Statistical analyses indicated a significant allometric effect of body size on skull PC1 values, suggesting that giant bears tend to have more elongated skulls. This implies a relationship in which larger individuals exhibit greater cranial elongation. In contrast, mandible PC1 values showed no size-related variation, indicating that mandibular shape is less influenced by overall body size. However, PC2 values in the mandible increased significantly with larger specimens, indicating a larger masseteric fossa in larger bears. This morphological adaptation potentially enhances feeding efficiency and bite strength in larger individuals, reflecting functional adaptations in brown-bear mandibular morphology. These findings contribute to our understanding of sexual dimorphism and size-related morphological adaptations in brown bears, providing insights into their adaptation biology and ecological roles within their habitats.

Mandibular shape and diet in extant primates: a 3D geometric morphometric analysis.

Establishing a link between mandibular morphology and diet in extant primates has long been a goal in biological anthropology because it should provide important insight into the diets of extinct primates, including fossil hominins. To date, efforts to explore this question have produced mixed results, largely perhaps due to a reliance on the use of 2D morphological data. Here, we report a study where we investigated whether 3D shape data would provide a clearer picture. We used geometric morphometrics to analyse 3D mandibular shape variation in a sample of > 200 primate specimens, representing individuals from 27 species and five families. Two sets of analyses investigated i) whether there was a relationship between mandibular shape and four standard dietary categories and ii) whether there was a relationship between mandibular shape and a well-known index of diet quality. We found an association between mandibular shape and the dietary categories when we employed raw Procrustes coordinates and allometry-free residuals, but the relationship was weak to non-existent when the effects of phylogeny were taken into account. We found no relationship between shape and the diet quality index, no matter whether the data were raw, corrected for the effects of allometry, corrected for the effects of phylogeny, or corrected for the effects of both allometry and phylogeny. Taken together, the results of the two sets of analyses suggest that there is a weak relationship between 3D mandibular shape and diet in extant primates. Allometry and phylogeny appear to be more important influences on the 3D shape of extant primate mandibles than is diet. We conclude from this that 3D analysis of mandibular shape is unlikely to further illuminate the diets of extinct primates, and research efforts should, therefore, be directed elsewhere.

Larval Taxonomy of the Caddisfly Cernotina truncona Ross, 1947 (Trichoptera: Polycentropodidae)

The genus Cernotina Ross, 1938 is represented in the southeastern United States by three nominal species: Cernotina calcea Ross, 1938, Cernotina spicata Ross, 1938, and Cernotina truncona Ross, 1947. Of all Cernotina species, only the larva of C. spicata has been described to date. The goal of this paper is to describe, illustrate, and diagnose the larva of C. truncona using ecologically associated specimens. In addition, we used publicly available mitochondrial DNA barcoding data to evaluate the genetic relationships of these species. The larvae of Cernotina truncona can be distinguished from those of C. spicata by differences in setal placement and number on the meso- and metanota, mandibular morphology, head width, and distal setation of the tarsi. The ultrastructure of the anal claw is figured, highlighting the novel finding of small spines on the concave margin of a larva of Cernotina. With this new description, just the second described larva from this genus, only C. calcea remains unknown in the southeastern United States. The information provided herein enables the in-depth study of the ecology and life history of this diminutive caddisfly.

Mandibular ecomorphology in the genus ursus (Ursidae, Carnivora): relevance for the palaeoecological adaptations of cave bears (U. spelaeus) from Scladina cave

ABSTRACT Considerable morphological and ecological diversity has been found in extinct and extant members of the bear genus, Ursus, and appears to be key in explaining how they have thrived across vast ecological gradients. One example is the cave bear Ursus spelaeus. We applied 2D geometric morphometric techniques to describe morphological changes in the mandibles of extant Ursus species to further interpret the palaeoecology of U. spelaeus. Ursus species were discriminated using their mandibular morphology, which showed intra and interspecific shape variation that was indirectly linked to climatic adaptations through dietary variation. Mandibles of bears that inhabit colder, drier and more seasonal environments were generally slender with large diastema and a dorsoventrally smaller ramus. In contrast, species from warmer environments with higher levels of precipitation were found to have a dorsoventrally taller ramus (relative to the corpus). Discriminant function analyses of the morphology of U. spelaeus suggested adaptations to a series of fluctuating environments through time, helping to assess previously proposed Marine Isotope Stages for sedimentary deposits in Scladina Cave. Our geometric morphometrics analyses of bear mandibular ecomorphology demonstrates how geometric morphometrics provides a valuable tool to enhance paleoenvironmental reconstructions within deposits of the same fossil site.

A large brachyopoid from the Middle Triassic of northern Arizona and the diversity of brachyopoid temnospondyls from the Moenkopi Formation

Brachyopoids represent a diverse and late surviving temnospondyl group, lasting until the Early Cretaceous. Here, we report on brachyopoid material previously assigned to Hadrokkosaurus bradyi that represents a distinct brachyopoid taxon, characterised by a smaller number of large, robust mandibular teeth, a feature rarely observed in other temnospondyls. We also revisit an angular previously referred to Hadrokkosaurus potentially belonging to other temnospondyl taxa present in the Middle Triassic of North America. In light of the abundance of material of possible taxa distinct from Hadrokkosaurus, we express the need to re-examine previously collected specimens as new information changes the landscape of palaeontology. Parsimony analyses using exclusively mandibular characters recover the new brachyopoid taxon from the locality in a polytomy with Hadrokkosaurus and Vanastega at the base of Brachyopoidea, adding to a diversity of mandibular morphology of temnospondyls in the Middle Triassic of North America.

A practical, step-by-step, guide to taxonomic comparisons using Procrustes geometric morphometrics and user-friendly software (part B): group comparisons

In this second part of the study, using a ‘clean’ dataset without very low precision landmarks and outliers, I describe how to compare mandibular size and shape using Procrustes methods in adult North American marmots. After demonstrating that sex differences are negligible, females and males are pooled together with specimens of unknown sex and species are compared using a battery of tests, that estimate both statistical significance and effect size. The importance of allometric variation and its potential effect on shape differences is also explored. Finally, to provide potential clues on founder effects, I compare the magnitude of variance in mandibular size and shape between the Vancouver Island marmot (VAN) and the hoary marmot, its sister species on the mainland. In almost all main analyses, I explore the sensitivity of results to heterogeneous sample size and small samples using subsamples and randomized selection experiments. For both size and shape, I find a degree of overlap among species variation but, with very few exceptions, mean interspecific differences are well supported in all analyses. Shape, in particular, is an accurate predictor of taxonomic affiliation. Allometry in adults, however, explains a modest amount of within-species shape change. Yet, there is a degree of divergence in allometric trajectories that seems consistent with subgeneric separation. VAN is the most distinctive species for mandibular shape and mandibular morphology suggests a long history of reduced variation in this insular population. Geometric morphometrics (GMM) is a powerful tool to aid taxonomic research. Regardless of the effectiveness of this family of methods and the apparent robustness of results obtained with GMM, however, large samples and careful measurements remain essential for accuracy. Even with excellent data, morphometrics is important, but its findings must be corroborated with an integrative approach that combines multiple lines of evidence to taxonomic assessment. The analytical protocol I suggest is described in detail, with a summary checklist, in the Appendix, not to miss important steps. All the analyses can be replicated using the entire dataset, which is freely available online. Beginners may follow all the steps, whereas more experienced researchers can focus on one specific aspect and read only the relevant chapter. There are limitations, but the protocol is flexible and easy to improve or implement using a programming language such as R.

Abnormalities in pharyngeal arch-derived structures in SATB2-associated syndrome.

SATB2-associated syndrome (SAS, glass syndrome, OMIM#612313) is a neurodevelopmental autosomal dominant disorder with frequent craniofacial abnormalities including palatal and dental anomalies. To assess the role of Satb2 in craniofacial development, we analyzed mutant mice at different stages of development. Here, we show that Satb2 is broadly expressed in early embryonic mouse development including the mesenchyme of the second and third arches. Satb2-/- mutant mice exhibit microglossia, a shortened lower jaw, smaller trigeminal ganglia, and larger thyroids. We correlate these findings with the detailed clinical phenotype of four individuals with SAS and remarkable craniofacial phenotypes with one requiring mandibular distraction in childhood. We conclude that the mouse and patient data presented support less well-described phenotypic aspects of SAS including mandibular morphology and thyroid anatomical/functional issues.

Pycnodysostosis: Characteristics of teeth, mouth and jaws.

To describe the clinical and radiographic oro-dental characteristics of patients with pycnodysostosis (PDO). A short interview and clinical examination of seven patients with PDO were performed as well as assessment of the temporomandibular joints and masticatory muscles using the diagnostic criteria for temporomandibular disorders, DC-TMD form. A full set of records were taken including photos and intraoral scan. Finally, existing cone beam computed tomography (CBCT) images and radiographs were also studied. All patients presented with bimaxillary micrognathia, five had a convex profile, and two had a straight profile. In addition, posterior open bite, Angle Class III molar relation with accompanying anterior crossbite and a grooved median palate were common findings. No patient showed symptoms of temporomandibular disorder (TMD) apart from some clicking. Finally, the main radiographic findings were the obtuse mandibular angle, the frontal bossing, the elongation of the coronoid/condylar process and the presence of hypercementosis with obliterated pulp chambers. The examined patients with PDO were characterized by dental crowding, malocclusion (anterior crossbite, posterior open bite), hypercementosis, obliterated pulp chambers and deviations in mandibular morphology. In conclusion, patients with PDO have a specific need for dental and orthodontic monitoring with focus on crowding and posterior open bite. The patients will benefit from a long-term orthodontic plan including extractions.

Studies on Neotropical crickets: A new Tusked Cricket genus (Orthoptera: Phalangopsidae) from Colombia.

Dentoluzara spatulatus n. gen. et n. sp., from the middle lands of the Colombian Andes, is described. This new phalangopsid cricket is distinguished by its asymmetrical mandibles with a basal prolongation in the left one, which is why it is recorded as the first Tusked Cricket. This rare morphological structure has only been observed in some species of anostostomatids and a couple of genera of tettigoniids, but never in crickets. Furthermore, D. spatulatus n. gen. et n. sp., has the ps. p2, from the male genitalia, spatula-shaped, deriving its specific epithet from there. Finally, the new genus peculiar mandibular morphology and the subfamily Luzarinaes taxonomy are commented and discussed.