Skull Type Research Articles

Precise Localization of the Central Left Frontal Cortex in Different Canine Skull Types: A Comparative Study of Frameless Neuronavigation and External Measurement Techniques

Repetitive Transcranial Magnetic Stimulation (rTMS), a non-invasive brain modulation technique, has been explored as an additional treatment option for behaviorally disordered dogs. For optimal effectiveness of the rTMS treatment, accurate coil positioning to the stimulation target is pivotal. Frameless stereotactic neuronavigation for the localization of intracranial regions has been established as a reliable targeting method. However, given the varying skull shape and brain structures among dog breeds, divided into mesocephalic, brachycephalic, and dolichocephalic breeds, localizing the rTMS target area, the central left frontal cortex, can be challenging. Previous neuronavigation studies have only investigated its use in mesocephalic breeds of dogs. Because this neuronavigation is based on expensive high-tesla magnetic resonance imaging data, and anesthesia needed for immobilization, a cheaper and reliable localization alternative to broaden the rTMS use in the veterinary field is needed.The objective of this study was twofold. First, the study aimed to evaluate external localization of the central left frontal cortex within the three skull types (retrospective study 1). Then, this external localization method was compared to the conventional frameless neuronavigation technique to check the consistency, focusing on mesocephalic and dolichocephalic breeds (prospective study 2). Thirty-two brachycephalic, thirty-seven mesocephalic and thirty dolichocephalic dogs were included to evaluate the external localization of the central left frontal cortex by external measurement (retrospective study 1, data obtained from previously performed MRI scans). For the second objective, thirty-eight dogs (35 mesocephalic breeds and 3 dolichocephalic breeds) were recruited to compare the external measurement localization method and the localization by neuronavigation (prospective study 2, data extracted from study 1 and former rTMS studies). The first part of this study showed the central left frontal cortex was externally located approximately two-thirds of the total skull length (sagittal length) in meso- and dolichocephalic dogs, at the center of the skull length in brachycephalic dogs, and 0.65 to 0.70 cm to the left of the cerebral midline for all skull types (retrospective study 1). Using intraclass correlation coefficient (ICC) analysis, the second part of the study showed high consistency between these two methods, for the length of the skull (0.94), the relative position of the left frontal cortex (0.84), and the distance to the cerebral midline (0.69) in mesocephalic and dolichocephalic breeds (prospective study 2). Our findings suggest that the conventional frameless neuronavigation could be replaced by the external localization method in the mesocephalic and dolichocephalic dog breeds, and therefore ultimately reduce anesthesia time and financial burden when applying non-invasive brain modulation techniques like rTMS. More research needs to be conducted for brachycephalic dogs to validate this method in this specific population of dogs.

Using a three-dimensional-printed device with the patient's maxillary dental impression allows to perform minimally invasive brain biopsies in dogs and cats: a preliminary study.

To develop an innovative process for stereotactic brain biopsies in dogs and cats that would provide a definitive diagnosis and optimize the management of patients with brain lesions. 4 dogs and 1 cat diagnosed with 1 or more brain lesion(s) underwent brain biopsies between March 24, 2023, and October 25, 2023. Based on trajectories selected on images of MRI and CT scan performed on each patient, a computerized software program was used to design a 3-D-printed patient-specific device with maxillary dental impression located on a baseplate to secure the patient's head and with insertion ports for the biopsy instrumentations located on a C-arm. As proof of concept, the device was successfully used in 2 cadavers before being used on clinical patients. All biopsy samples were submitted for histopathological examination. Histological diagnosis was obtained in 80% (4/5) of the cases (choroid plexus tumor, astrocytoma, meningioma, and chronic meningoencephalitis of unknown origin). In 1 patient, the results of biopsy were nondiagnostic; postmortem diagnosis was consistent with a low-grade oligodendroglioma. All the patients were discharged within 24 hours after the procedure without complications. This novel stereotactic system allows the surgeon to perform safe, easy-to-use, inexpensive, and minimally invasive precise brain biopsies in dogs and cats, without complications. This unique technique could be applied to any size and type of skull and for any type of brain lesions and would provide diagnostic information that would be valuable for future treatment planning and prognosis.

Effectiveness of a Daily Honeycomb-Shaped Dental Chew in Reducing Calculus, Plaque, Gingivitis and Malodor in Dogs.

Periodontal disease in dogs is common. Client compliance with oral hygiene and oral care for pets is low. The gold standard is annual dental prophylaxis under general anesthesia with imaging followed by home care including daily brushing. Clients should be offered methods to reduce calculus, plaque, gingivitis, and resulting halitosis that are time efficient, cost-effective, and easy to administer between annual preventative dental prophylaxis with the goal to move into maintenance phase of managing periodontal disease. This study aimed to evaluate the efficacy of a honeycomb-shaped dental chew in reducing hardened calculus, plaque, gingivitis, and malodor in client-owned dogs in their normal home environment including various breeds, skull types, ages, and weights. Calculus, plaque, and gingival scores with volatile sulfur compounds readings were performed under sedation and evaluated under general anesthesia after 60 consecutive days of receiving a daily honeycomb-shaped dental chew treat. There was an overall statistically significant percentage reduction of calculus (26.6%), plaque (14.2%), and malodor (46.71%). Gingival scores did not demonstrate statistically significant reduction (0.99%). Use of this honeycomb-shaped daily dental chew significantly reduced calculus, plaque, and associated malodor in dogs when fed consecutively for 60 days.

Morphological and morphometric measurement of the temporomandibular joint of small and medium-weight dogs with different skull shapes.

The recognition and diagnosis of canine temporomandibular joint (TMJ) disease can be a challenge, often leaving them undiagnosed. Although computed tomography (CT) has proved to be highly efficacious in detecting joint disease in the TMJ, morphometric and morphological studies of the normal TMJ have been scarce. Especially, skull type specific anatomical differences of the TMJ in dogs of different weights and skull morphologies have received limited attention. This study aimed to compare the TMJ morphologies of dogs across different weight classes and skull types. Retrospective study. CT scans were used to measure the depth and width of the Fossa mandibularis and two angles between the Fossa mandibularis and the Caput mandibulae in a total of 92 dogs and 182 mandibular joints, respectively. The TMJ varied in terms of weight groups and skull indices. Shallow mandibular pits, underdeveloped retroarticular processes, and reduced joint congruency were observed particularly in light-weight and brachycephalic dogs. Conversely, dolichocephalic animals displayed deep joint pits, pronounced joint congruency, and a well-developed Processus retroarticularis. Observer learning curve; not every skull shape was represented in each weight group.

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.

The Frequency of Occipital Spurs in Relation to the Cephalic Index: An Anatomorphometric Cone Beam CT Study.

The occipital spur (OS) can be described as an abnormal elongation of the external occipital protuberance (EOP). The cephalic index (CI) refers to the ratio of width to length in any skull. The aim of the present study was to evaluate the frequency and types of OS. It also aimed to determine the mean CI and the distribution of skull types using cone beam computed tomography (CBCT). And to determine if there was a relationship between the cephalic index and the presence and types of OS. CBCT scans from 523 patients were included in the study. OSs were classified as type 1 (flat), type 2 (crest), and type 3 (spine). Skull length and width were measured on axial sections and the CI was calculated. Based on the cephalic index (CI), skull types were classified as dolichocephalic (CI < 75), mesocephalic (75 < CI < 80), brachycephalic (80 < CI < 85), and hyperbrachycephalic (CI > 85). The most common cranial types in the study group were brachycephalic (44.7%), mesocephalic (28.3%), hyperbrachycephalic (21.2%), and dolichocephalic (5.7%). Regarding the presence of OS, 54.3% of the participants had no OS, 23.1% had flat type, 15.3% had crest type, and 7.2% had spin type OS. There was a statistically significant difference (P < 0.05) in the frequency of OS according to skull type. This study, the first to evaluate CI and OS using CBCT, concludes that brachycephaly is the most common cranial type. OS is more common in mesocephalic and dolichocephalic skulls, at older ages, and in males.

The Differences in Radiographic Vertebral Size in Dogs with Different Chest and Skull Types

The objective of this study was to elucidate the differences in vertebral length, vertebral height, and vertebral length/height ratio of the fourth thoracic vertebra (T4), the second lumbar vertebra (L2), the fifth lumbar vertebra (L5) and the seventh lumbar vertebra (L7) based on radiographs in dogs with various body sizes, skull types, and thoracic conformations and to determine the relationships of these parameters with age and sex. A total of 258 dogs were included in this study and classified by three criteria—BW (Criterion 1), skull type (Criterion 2), and thoracic conformation (Criterion 3). Age had weak negative correlations with vertebral length and height. Sex did not affect the vertebral size parameters. BW had strong positive correlations with vertebral length and height, but there was no influence of BW on vertebral length/height ratio. Regarding the different body sizes and conformations, large breeds had vertebrae with significantly greater length and height than small and medium breeds (p &lt; 0.001). In Criterion 2, the vertebrae of the mesocephalic dogs had significantly greater length and height than those of the brachycephalic and dolichocephalic dogs (p &lt; 0.05). In Criterion 3, both deep-chest and round-chest dogs had vertebrae with significantly greater length and height than the barrel-chest dogs (p &lt; 0.0001). Only vertebral length/height ratios of T4 were not influenced by age, sex, BW, skull type, and thoracic conformation. Age, differences in body size, skull type, and thoracic conformation could affect the vertebral size in dogs. Therefore, using breed-specific vertebral lengths and/or heights is a better approach for comparative radiographic analysis with vertebral measurements.

Prevalence of root fusion in canine maxillary second molar teeth using cone-beam computed tomography

This study evaluated the prevalence of root fusion in the right and left maxillary second molar teeth in dogs using cone-beam computed tomography (CBCT). A total of 180 dog CBCT scans, or a total of 360 maxillary second molar teeth, were analyzed in this study. Dogs were divided into weight categories of small (&amp;lt;10 kg), medium (10–25 kg), and large (&amp;gt;25 kg). Skull type (brachycephalic, mesocephalic, dolichocephalic) and sex were also recorded for each dog. Overall, 65% of maxillary second molar teeth had some type of root fusion. Of the teeth that had fusion, the only configuration represented was fusion of the distobuccal root with the palatal root. The most common root morphology overall (all dogs and both right and left maxillary second molar teeth included) was partial fusion (177/360, 49%). With the high prevalence of fused roots in maxillary second molar teeth in dogs found in this study, CBCT will help clinicians to more accurately assess a dog's anatomy and implications for treatment.

Variants of the typical variability of alveolar arches in different craniotypes

Background. The implementation of the principles of evidence-based medicine in applied and fundamental research consists in the precision of morphometric measurements in determining the types, dimensions and spatial location of the facial and cerebral parts of the skull. Published scientific data on the variability of morphometric parameters of the alveolar arches are contradictory and heterogeneous due to the lack of definition of interdependencies with gender, age characteristics and individual features of the skull.Goal. Investigation of the regularities between morphometric values and forms of the alveolar arches of the upper jaw in mesocrane, brachycrane and dolichocrane types of the skull.Materials and methods. Morphometry was performed on 93 preparations of skulls with lower jaws of both sexes of the first and second periods of adulthood with physiological types of bite and the shapes of the alveolar arches of the upper jaw were established. Taking into account the value of the transverse-longitudinal index, the skulls of mesocrane (n=54; 58.1%), brachycrane (n=23; 24.7%) and dolichocrane (n=16; 17.2%) types were identified. The length, width, depth and diagonal of the alveolar arches were studied as morphometric parameters.Results. The minimum and maximum limits of fluctuations of values, average statistical indicators, coefficients of variation are determined. The variability of the parameters of the alveolar arches of the upper jaw depending on the shape of the facial skull and gender characteristics was established. It is proved that the smallest values of the depth of the alveolar arch of the upper jaw are noted in brachycranes, the largest – in dolichocrans, while the smallest dimensions of the length, width of the alveolar arch of the upper jaw are determined in dolichocrans, and the largest – in brachycranes, while the smallest diagonal values of the alveolar arch of the upper jaw are revealed in mesocrans.Conclusions. The shape of the alveolar arches in the mesocrane type of skull has a proportional arcuate shape, in brachycrania − an arcuate «wide and short» shape, in dolichocrania − an arcuate «narrow and long» shape. The obtained new data on the variant variability of the alveolar arches should be used when planning treatment tactics for patients with complete adentia.

Three-Dimensional Volume Rendering in Computed Tomography for Evaluation of the Temporomandibular Joint in Dogs.

Based on computed tomography (CT) images, volume rendering was used to obtain a three-dimensional representation of data (3DVR). The aims of this study included: describing the bone anatomy of the temporomandibular joint (TMJ) of dogs; comparing the TMJs of each dog by skull type and age; comparing 3DVR images with three-standard-plane CTs; assessing soft tissues adjacent to the TMJ and assessing pathological cases. Multidetector computed tomography scans of bilateral TMJs of 410 dogs were observed. From a ventral view, slight displacements in the positions of the skulls were seen, whereas from a caudal view, differences in amplitude of the articular space were observed. Dolichocephalic and mesaticephalic dogs showed more similar TMJ features than brachycephalic dogs. The shape of the TMJ bones were irregular in dogs under 1 year old. The 3DVR images related to the three-standard-plane CT improved the overall comprehension of the changes in the articular space amplitude and condylar process morphology. The fovea pterygoidea, mandibular fossa and retroarticular process were perfectly shown. A better spatial situation of adjacent soft tissues was obtained. The 3DVR represents an ancillary method to the standard-plane CT that could help in the understanding of the anatomy and diagnoses of different pathologies of the TMJ in dogs.

The Anatomy of the Stomatognathic System in Different Skull Types in Dogs.

The anatomy of the stomatognathic system is important for both clinical evaluations and surgical approaches in all animal species. The aim of this study was to describe the innervation and vascularization of the stomatognathic system of the dog. Twelve dogs without a history of disease or cranial malformation were used: 4 brachycephalic, 4 mesocephalic, and 4 dolichocephalic. The dogs were dissected, and arteries, veins, and nerves related to the masticatory and swallowing components were identified. The distribution pattern of these structures in the 3 different skull types were observed. The entire blood supply of the stomatognathic system is derived from the external carotid artery, which originates from the common carotid artery, and terminates as it branches into the superficial temporal and maxillary arteries. The other main branches of the common carotid artery are the occipital, cranial laryngeal, ascending pharyngeal, lingual, facial, caudal auricular, and parotid arteries. Blood drainage was achieved via the external jugular vein, which originates from the union of the linguofacial and maxillary veins. Brachycephalic dogs had blood vessels with greater sinuosity (more deviations) when compared to dolichocephalic and mesocephalic dogs. The stomatognathic system innervation of brachycephalic skull dogs showed differences in the distribution of the facial nerve in the labial commissure and maxillary and mandibular regions. The cranial conformation of dogs demonstrated anatomical variations of the vascular and neural structures of the stomatognathic system. This data may be useful to improve clinical practice, surgical planning, and interpretation of clinical dysfunctions.

Challenges of transsphenoidal pituitary surgery in severe brachycephalic dogs.

Transsphenoidal hypophysectomy is the standard surgical technique for the excision of pituitary neoplasms. Anatomy may be more obscured in brachycephalic skull types due to the crowding of soft tissue and osseous structures. We describe the unique challenges to approach the sphenoid bone and localize the correct burr hole site in severe brachycephalic dogs. A single institution retrospective case series of brachycephalic dogs with pituitary-dependent hypercortisolism (PDH). Preoperative computed tomography enabled 3D-, and cross-sectional reconstruction to plan and dry-practice the position of the ideal burr hole in relation to the sella turcica, pterygoid hamular processes, and hard palate. Rostral burring of the caudal hard palate obscuring the direct sphenoid approach necessitated adaptations to the original transsphenoidal hypophysectomy procedure. Postoperative outcomes and complications with respect to those seen in mesocephalic dogs are described. Ten brachycephalic dogs including French Bulldogs (n = 9) and a single Dogue de Bordeaux were included. All dogs were diagnosed with PDH and had preoperative advanced imaging performed on the skull. All but one dog had an enlarged pituitary gland, with a median pituitary/brain value of 0.5 (range 0.21-0.9). A total of 11 transsphenoidal hypophysectomy procedures were performed in these 10 dogs. Rostral extension of the soft palate incision into the hard palate was performed to access the burr hole site on the sphenoid bone. Major complications included aspiration pneumonia (n = 1), severe gastroesophageal reflux (n = 1), and central nervous signs (=1). All dogs survived until discharge, with a median time to follow-up of 618 days (range 79-1,669 days). Seven dogs experienced long-term remission of PDH. Brachycephalic dogs undergoing transsphenoid al hypophysectomy benefit from meticulous presurgical planning and extension of the approach into the caudal hard palate. Advanced surgical skills can render a good outcome in a technically challenging environment.

Cross Sectional Analysis of Eurasian Skull Anatomy for 3D Cephalometry-Normative Data Reveal Four Different Skull Types.

The unsolved problem in three-dimensional surgical planning for patients with facial deformity, dysgnathia, or asymmetry is the lack of a normative database of "norm skulls" that can be used as treatment objectives. A study was conducted on 90 Eurasian persons (46 male and 44 female adults) for whom cone beam-computed tomography images were available. Inclusion criteria were adult patients with a skeletal Class I pattern, proper interincisal relationship with normal occlusion, the absence of an open bite both in the anterior and posterior region, and a normal and balanced facial appearance; patients with dysgnathia and malformations were excluded. A total of 18 landmarks were digitized and 3D cephalometric measurements were performed and analyzed by means of proportions calculated from the landmarks. Male and female skulls were analyzed, as well as subdivisions revealed by cluster analysis. The data showed that four subtypes of skulls were distinguishable with statistical significance (p < 0.05). A male and a female type subdivided in a brachiocephalic and dolichocephalic phenotype could be identified. For each type, a mean shape was calculated by a Procrustes transformation, which, in turn, was used to create four template skulls from a male and a female skull. This was accomplished by fitting the polygon models of the two skulls to each of the two subtypes based on the landmarks marked on them using a thin plate spline transformation. The normative data of the subtypes can individually serve as a guide for orthodontic surgery in the Eurasian population, which is especially helpful in 3D planning and the execution of craniofacial operations.

Of Tongues and Skulls: The Influence of Race on Language Sciences in 1930s Turkey

ABSTRACT: In the 1930s, historiography in Turkey underwent a massive shift. Among the primary interests that emerged as part of the new nationalist historical narrative were a fascination with the physical appearance and the language of the ancient Turks. This paper explores one specific connection between these two topics: the influence that racial anthropology exerted over historical linguistics. By using the speeches made at the First and Second Historical Conferences, and those documented from the first three Turkish Language Congresses, I identify the seeds that were sown for a racial linguistics. I track the evolution of arguments for a physiological basis to narratives about language development, and the eventual harvest of a clear view about the importance of skull types for histories of language. The paper ends with a brief look at the fates of those engaged in enunciating a racialist linguistics in Turkey.

Time and sequence of the replacement of the deciduous by the permanent dentition in dogs and its applicability for age estimation.

This study investigated the influence of several covariates on the time and sequence of permanent dentition emergence following exfoliation of the deciduous teeth in puppies. The aim was to determine whether the emergence of permanent dentition can be used to assess whether a puppy that is traded across borders in the EU has reached the legally required minimum age of 15 weeks. The events were evaluated in a longitudinal study, with some cross-sectional observations, of 440 puppies belonging to 82 breeds. No significant differences were found between the left and right sides of a puppy's dentition nor between male and female puppies. Breed size and skull type had a significant impact: both the appearance and the completion of tooth eruption occurred considerably later in small or toy breeds and brachycephalic skull type breeds. The sequence of emergence differed little between maxillary or mandibular quadrants or between breeds. The first emerging elements were the maxillary first premolars or first incisors or the mandibular first incisors. The emergence of a permanent tooth usually occurred within 3 days before or after exfoliation of its precursor, except for the canines, which demonstrated a wider tooth replacement interval. This study presents standards for age assessment based on the emergence of permanent dentition for breeds of different sizes, using median ages or cumulative emergence percentages. However, the legal age determination of puppies with an assumed age of 15 weeks cannot be performed based on permanent dentition emergence, as this occurred at a later age in a large proportion of dogs (at least 95%) in our studied population. The probability of being at least 15 weeks old when at least one maxillary tooth has emerged was at least 72.25%, depending on breed size.

A Cross Sectional Study of Cephalic Index using Various Measurement Techniques in Varanasi Region of North Indian Population

Background: Cephalic Index is defined as the ratio calculated by the occipitofrontal diameter (OFD) to thebiparietal diameter (BPD).It has been reported that factors like race, ethnicity, genetic interactions, traditions, nutrition, environment, andclimate influences head types.The multifariousness of our nation fascinates and raises the need for anthropometric studies in various regionsand compare the outcomes.The cross-sectional study was carried on three different groups/subjects of either sex.Group 1 comprised of living subjects (Undergraduate students) belonging to this particular region.Group 2 comprised of those that presented to the radio- diagnosis department of Sir Sunderlal Hospital, IMS,BHU, UP, India.Group 3 comprised of dry skulls available in the departmental museum of department of Forensic medicine, IMS,BHU, UP, India.The measurement of maximum cranial breadth and maximum cranial length, are taken manually/on DICOM CTrecords depending on the group and recorded for analysis.The average CI in both the sexes and prevalence of the type is classified according to Martin and Saller classification.(1957)Objectives: The objectives were to find out the prevalence of the type of skull in the study population. It wouldalso show the sensitivity of radiology and its efficaciousness in anthropometric measurements. To ascertain themean CI,range of maximum cranial breadth and maximum cranial length.Result: A total of 70% amongst the study population shows dolichocephalisation.The mean cephalic index in this particular study population was 73.92 ± 5.05.&#x0D; Maximum cranial breadth ranged from 10.4cms to 16.2cms with a mean breadth of 13.21±0.93.Maximum cranial length ranged from 15.6 cms to 20.67cms with a mean length of 17.89 ± 0.86.Conclusion: The observations and findings of the present study based on CT can be replicated in variouscommunities, castes, and regions of India. The data can also be helpful in establishment of identity particularlyrace using skeletal remains.

Analysis of the anatomic relationship of the infraorbital canal with the roots of the maxillary fourth premolar tooth in the three different skull types: Mesocephalic, brachycephalic, and dolichocephalic, using cone beam computed tomography.

The objective of this retrospective descriptive study was to describe variations in the anatomic position of the infraorbital canal relative to the mesial and distal roots of the maxillary fourth premolar tooth for the three canine skull types (mesocephalic, brachycephalic, and dolichocephalic) using cone beam computed tomography. The study evaluated the position of the infraorbital canal in 120 canine patients (240 teeth) that presented to a private dentistry referral practice for reasons unrelated to the study. There were 40 patients for each skull type, determined by breed and facial index calculation. A grid system was used to determine the anatomic positions of the infraorbital canal relative to the roots of the maxillary fourth premolar tooth. The infraorbital canal's most frequent position at the mesial roots level for the total population (38.8%) and the mesocephalic skull type (53.8%) was apical to the furcation. For the brachycephalic (40.0%) and the dolichocephalic skull types (40.0%), the most frequent position was partially in the furcation and partially apical to the furcation. The most frequent position of the infraorbital canal at the level of the distal root was apical and palatal to the distal root for the total population (36.7%), the mesocephalic skull type (42.5%), and the brachycephalic skull type (35.0%). For the dolichocephalic skull type, the most frequent location of the infraorbital canal was both directly palatal and partially apical and palatal to the distal root (42.5%). For the brachycephalic skull type, the distal root was most frequently positioned caudal to the maxillary foramen/floor of the orbit (62.5%). Based on these findings, extra care must be taken with the dolichocephalic and the brachycephalic skull types to avoid iatrogenic trauma to the infraorbital canal and the orbit during surgical procedures on the maxillary fourth premolar tooth.

Tear film breakup time and Schirmer tear test in normal dogs: Effects of age, sex, reproductive status, skull type, and nasolacrimal duct patency.

The present study aimed to determine the effects of age, sex, reproductive status, skull type, and nasolacrimal duct (NLD) patency on tear production and tear film breakup time (TBUT) in normal dogs. The ophthalmic data of 82 healthy adult dogs were evaluated in this study. Age, sex, breed, and reproductive status were recorded. Schirmer tear test (STT) and TBUT were assessed in all dogs, and interferometry was available for the selected dogs. The Jones test was used to evaluate NLD patency. The cephalic index (CI) was calculated for each dog (skull width/skull length ×100). Mean (SD) values for the STT results for the right (OD) and left (OS) eyes were 20.6 (2.7) and 20.2 (2.7) mm/min, respectively. Mean (SD) TBUT values for OD and OS were 6.5 (2.5) and 6.1 (2.3) mm/min in all dogs, respectively. Sex and reproductive status had no significant effect on STT and TBUT (P[OU] > 0.05). Skull type significantly affected TBUT in both eyes (P(OD) =0.01, P(OS) =0.003), but had no effect on STT (P[OU] > 0.3). Age had no correlation with STT and TBUT in either eye (P[OU] > 0.05). STT and TBUT had no correlation in either eye (P[OU] > 0.2). NLD patency had no significant effect on STT or TBUT (P[OU] > 0.1). The results of this study showed lower TBUT values in brachycephalic breeds than in non-brachycephalic breeds. A compensatory increase in STT values was observed in dogs with low TBUT values.

Assessment of corneal and limbal epithelial thickness by spectral-domain optical coherence tomography in brachycephalic and non-brachycephalic dogs.

To investigate the variance in corneal epithelial thickness (CET) and limbal epithelial thickness (LET) according to the age and skull type by using spectral-domain optical coherence tomography (SD-OCT) in normal dogs. This study used an eye each from 46 dogs (24 brachycephalic and 22 non-brachycephalic dogs) assessed to have clear corneas. Each dog was classified according to age into groups 1 (0-5 years), 2 (6-10 years), and 3 (>11 years). OCT imaging was performed on the central cornea for CET and perpendicular to the quadrant of the limbus for LET. The average of the maximum LET (maxLET) value was measured in four eye quadrants. Corneal epithelial thickness was not significantly different according to age in brachycephalic and non-brachycephalic dogs. Visualization of the limbal invagination was better when the maxLET was thick. Nasal and temporal maxLETs were significantly thicker than superior and inferior maxLETs in non-brachycephalic dogs. In brachycephalic dogs, there was a significant decrease in nasal maxLET with age (rs =-0.489, p=.015). Significant differences between brachycephalic and non-brachycephalic dogs were observed in nasal maxLET (p=.024) and temporal maxLET (p=.011). Invagination was better visualized in the nasal and temporal limbal quadrants of non-brachycephalic dogs compared with brachycephalic dogs, and the maxLETs of the regions were thicker than those of the brachycephalic dogs. CET and LET measurements using SD-OCT can help in clinical assessment and research on ocular surface diseases in dogs.

The anatomical relationship between the mandibular first molar roots and the mandibular canal based on breed size and skull type.

The first molar is the largest tooth in the dog mandible with roots often extending to the level of the mandibular canal (MC). The anatomical relationship between the roots and MC is variable and the normal relationship between those structures in a diverse population of dogs has not been established. The lingual location of the roots relative to the MC poses a risk for iatrogenic trauma during dentoalveolar surgery, and it is unknown if certain skull conformations are predisposed to this relationship. This study aimed to identify associations between patient weight and skull type with molar tooth root location. CT scans performed for reasons unrelated to the study were retrospectively analyzed. Subjects were sorted into one of 12 groups (n=16 per group) based on skull type (brachycephalic, mesaticephalic, and dolichocephalic) and weight (extra small: ≤ 6.8 kg, small: >6.8 to ≤ 13.6 kg, medium: >13.6 to ≤ 25 kg, and large >25 to ≤ 38.6 kg). The mandibular first molar roots were categorized as lingual, buccal, or dorsal relative to the MC. Lingual root location was diagnosed in 50.0% of all roots evaluated, and 64.2% of all dogs assessed had at least one root in the lingual position. The size was shown to be protective, with lingual root location being significantly less likely as size increased. The exception to this was in large brachycephalic patients, which had rates of lingual roots similar to smaller dogs. Buccal roots were rarest, diagnosed in only 9.7% of all roots, and were most common in brachycephalic patients, which had 83.8% of all buccal roots. Additional caution should be employed when removing alveolar bone during surgical extraction in dogs ≤ 13.6 kg and in large brachycephalic patients (boxers) to avoid iatrogenic trauma to the neurovascular bundle.