825 research outputs found
Computed tomographic assessment of equine maxillary cheek teeth anatomical relationships and paranasal sinus volumes
No full textDisorders affecting the equine maxillary cheek teeth and paranasal sinuses are relatively common, but limited objective information is available on the dimensions and relationships of these structures in horses of different ages. The aims of this study were to assess age-related changes in the positioning and anatomical relationships of the individual maxillary cheek teeth with the infraorbital canal and maxillary septum and the volumes of the individual sinus compartments. CT and gross examination were performed on 60 normal equine cadaver heads that were aged by their dentition. The intrasinus position of cheek teeth, length of reserve crowns, relationship to the infraorbital canal and measurements of rostral drift and sinus compartment volumes were assessed from CT images. The findings included that Triadan 10 alveoli lay fully or partially in the rostral maxillary sinus (RMS) in 60% of cases. The infraorbital canal lay directly on the medial aspect of the alveolar apex in younger horses. The Triadan 11’sclinical crowns and apices drifted a mean of 2.48 and 2.83 cm more rostral to the orbit, respectively, in the >15 years old vs the <6 years old age group. The mean volumes of sinus compartments ranged from 175 cm3 for the caudal maxillary sinus (CMS) to 4 cm3 for the ethmoidal sinus (ES). This information should be of value in the diagnosis and treatment of equine dental and sinus disorders and as reference values for further studies
Computed tomographic and pathological study of equine cheek teeth infundibular caries
No full textSeveral studies have found equine maxillary cheek teeth infundibular disorders to affect most adult
horses. Even infundibulae that appear grossly normal on the occlusal surface may contain areas of
caries, defective cementum, or complete absence of cementum subocclusally. These defects can
range from possibly insignificant small developmental cemental defects deep in the infundibulum to
advanced coalescing infundibular caries leading to dental fracture.
The aim of this study was to characterize maxillary cheek teeth infundibular disorders by gross,
computed tomographic, and histopathological examinations of affected and control teeth. One
hundred maxillary cheek teeth that contained 200 infundibulae were extracted post-mortem from 30
horses, including 82 teeth with and 18 without occlusal surface infundibular caries. The occlusal
surface infundibular caries was graded using the modified Honma technique, which found 61.8% of
the 82 affected teeth to be affected by Grade 1 caries, 27.9% with grade 2 and 10.3% with grade 3
caries. The rostral infundibulae were more commonly affected by occlusal surface lesions (72%
affected) as compared to the caudal infundibulae (64% affected) and also had higher grades of
occlusal caries. The Triadan 09 position was greatly overrepresented in the diseased teeth,
comprising 50% (41/82) of teeth with visible occlusal caries. There was a significant association
between the grade of occlusal infundibular caries present and the Triadan positions of the teeth.
All teeth were then imaged by computed tomography (CT) to determine crown and infundibular
lengths, and to detect the presence and appearance of any subocclusal infundibular cemental
abnormalities. Extensive statistical analysis of dental crown and infundibular lengths were performed,
showing that relatively shorter infundibulae are more likely to be diseased. However, this finding can
be explained by the predominance of Triadan 09 and older teeth in the diseased group, both of which
have lower infundibular depth:crown length ratios. Computed tomography showed 182/200 (91%)
infundibulae to have infundibular lesions deep to the occlusal surface. No statistically significant
association was found between the presence of subocclusal infundibular defects and age of affected
horses, grade of caries, or the presence of visible occlusal infundibular lesions. Teeth affected by
occlusal caries were 1.3 times more likely to have subocclusal lesions than teeth without occlusal
caries. This study also proposes a relationship between the presence of developmental infundibular
cemental lesions and later caries formation.
Eight maxillary cheek teeth were then imaged using micro-computed tomography (microCT) which
provided much finer details of infundibular lesions. MicroCT images were also used to guide the sites
of sectioning of teeth for histopathological analysis, which found that the appearance of infundibular
cementum was much more variable than its appearance on standard CT or microCT. The cementum
of many infundibulae showed extensive sites of former vasculature that were not filled with
cementum. Other areas contained moth-eaten cement which often contained plant material and
cellular debris, independent of the appearance of the occlusal surface of the infundibulum. No
histological evidence of previous vasculature or of haemoglobin breakdown products were found in
infundibular cementum.
Major findings and interpretations of this study allow us to conclude:
- Many infundibulae are affected by occult subocclusal cemental lesions. These lesions appear
to have no association with the presence or absence of apparent occlusal surface infundibular
lesions, and also are not more significantly apparent in particular Triandan positions or in
horses of a particular age. As the subocclusal cemental lesions appear to be unrelated to the
presence of occlusal surface lesions, the relationship between infundibular cemental lesions
(both occlusal and subocclusal) and the development of clinical sequelae remains poorly
understood.
- Even in those infundibulae with no apparent occlusal surface infundibular caries, the
subocclusal region often contained hypoplastic cementum and, often, impacted feed material
at the most apical aspect of the infundibulum on histological examination. Therefore, there
must be a communication between the apical portion of the infundibulum and the occlusal
surface for this to occur, even in those that appear unaffected by a vascular channel defect or
infundibular caries.
- The strict definition of infundibular caries as opposed to normal cementum on the occlusal
surface of infundibulae is inadequate to describe the great variation in the appearance and
composition of infundibular cementum. Further classification of the subocclusal cemental
defects and expectations of normal subocclusal cementum may also be included for a more
complete understanding. There should be a standardisation of terminology used to describe
normal and defective infundibular regions both on the occlusal surface and subocclusally.
- It is likely that subocclusal cemental lesions, particularly areas of apical cemental hypoplasia,
become become impacted with feed material even before they are exposed on the occlusal
surface, which may allow severe (Grade 2 or 3) infundibular caries to form subocclusally long
before that portion of the tooth is exposed.
- Analysis of the Hounsfield Units (measurement of density of tissues on CT scan) and their
relationship to the histological appearance of the same tissues may allow us to determine if
an infundibulum contains normal or hypoplastic cementum, or impacted feed material without
more invasive investigatory methods
Anatomical, pathological and clinical study of donkey teeth
No full textEighty normal cheek teeth and 26 normal incisors extracted from 14 donkeys (median age 19
years) at post mortem were anatomically examined including grossly and by computerised axial
tomography (CAT) imaging. Decalcified histology was performed on 54 sections from 18 teeth
(8 donkeys), undeclacified histology on 16 sections from 7 donkeys and scanning electron
microscopy on 10 sections from 10 teeth (3 donkeys). The dental formulae and tooth number
was found to be the same as in horses with a higher prevalence (17 %) of canine teeth in female
donkeys. A decrease in tooth length, pulp horn length and pulp horn width with age was
illustrated, as was an increase in occlusal secondary dentine depth with age, although not all
these age changes were statistically significant. Normal histological and ultrastructural features
of donkey teeth were identified and found to be similar to equine findings. Enamel was found to
be thicker buccally in both maxillary and mandibular cheek teeth. Quantitative measurements of
transverse dentine thickness around pulp cavities, dentinal tubule diameters and densities, and
enamel prism diameters were made. Left lower incisors (301) were extracted from 7 donkeys
and 6 horses for micro-hardness determination of enamel, primary and secondary dentine using a
Knoop Hardness indenter. No significant difference between donkey and horse incisor
microhardness was demonstrated. Examination of 19 donkey skulls at post mortem examination
showed donkeys to have a higher degree of anisognathia (27%) compared to horses (23%).
Post mortem dental examination of 349 donkeys (median age 31) demonstrated a high
prevalence of dental disease (93%) and in particular cheek teeth diastemata (85%). Furthermore,
age was associated with increasing prevalence of dental disease and diastemata. Diastemata were
also associated with the presence of other dental disorders and with colic-related death in
affected donkeys. Quantitative measurements of 45 diastemata from 16 donkeys showed no
difference in the medial and lateral width of diastemata but periodontal pockets were deeper
laterally. The definition of valve and open diastemata were confirmed. Pulp exposure, dental
caries and periodontal disease were examined in detail (54 skulls) at post mortem. A total of 19
teeth were extracted for further detailed examination as performed in normal anatomy.
Clinical dental examinations were performed on 357 donkeys in the U.K. that were selected for
age distribution, and the prevalence of dental disease in different age groups was found to
increase from 28% in the youngest group (age 0-10 years) to 98% in the oldest group (age > 35
years). An increased prevalence of most dental disorders with age was demonstrated as was an
association between dental disease and weight loss, poor body condition score, supplemental
feeding and previous episodes of colic. Clinical dental examination of 203 working donkeys in
Mexico showed similar types of dental disorders as found in the U.K. study, with dental disease
present in 62%, of which 18% required urgent dental treatment. There was a significant
association between age groups and dental disease, and age groups and body condition score, but
there was no association between dental disease and body condition score. However, body
condition score was not associated with supplemental feeding or faecal egg counts either
Epidemiological, pathological and microbiological study of equine dental caries
No full textDental caries is caused by acidogenic oral micro-organisms which convert
fermentable carbohydrates to acids that damage the tooth by causing a
demineralisation and disintegration of the inorganic and organic substances of the
tooth, respectively (Soames and Southam, 2005). In horses, two variants of dental
caries occur: equine dental peripheral caries (PC) involving the periphery of teeth;
and infundibular caries (IC) of the maxillary cheek teeth.
Twenty-five veterinarians and equine dental technicians experienced in equine
dentistry were recruited to perform a UK-wide survey and examined 706 horses for
the presence PC and IC, as well as for concurrent dental disorders. The recorded
survey results for individual horses included data on potential risk factors including
breed, sex, age, diet and the postcode of stables. The prevalence of PC and IC in this
population, was 51.7% and 45.5%, respectively. The most commonly and severely
PC affected teeth were the three caudal cheek teeth (Triadan 09-11) and for IC were
the Triadan 09s. In a multivariable model without observer as a random effect,
potential risk factors for the development of PC were: the presence of IC, the
presence of diastema/periodontal disease (PD), the presence of multiple concurrent
dental disorders other than IC, being fed 2.1-3.0 kg concentrates per day, and living
in South East England and South West England. The risk factors which remained
significantly associated with the presence of PC in a multivariable model with
observer as a random effect, were: feeding 2.1-3 kg concentrates per day, multiple
concurrent dental disorders other than IC, the presence of diastema/periodontal
disease; additionally, dental fractures now became significantly associated with the
presence of PC. In a multivariable model without observer as a random effect,
potential risk factors for the development of IC were: the presence of PC, the
presence of multiple dental disorders other than IC, and increasing age. Horses in
North England and South West England were significantly less likely to have IC than
horses in other regions of England and Scotland. In a multivariable model with
observer as random effect, the only remaining risk factors were increasing age and
geographical region, with a significantly lower likelihood for horses to have IC in
South West England than in the other regions.
A molecular microbiological study on equine dental caries using a linear
discriminant analysis effect size (LEfSe) at genus or higher level, showed Gemella
and Actinobacillus to be the genera most associated with the PC study control group
(no PC), and Streptococcus, Olsenella and Scardovia to be the genera most
associated with PC. Additionally if LEfSe was performed at genus level only, then an
additional genus shown to be associated with PC was Mitsuokella. The genus most
associated with IC using LEfSe at genus or higher level was Acidaminococcus, while
Bacillus was the genus most associated with the IC study control group (no IC).
A pathological study examined PC-affected cheek teeth grossly, histologically and,
by scanning electron microscopy (SEM) and transmission electron microscopy
(TEM). Dental plaque, containing bacteria was found to cover the PC lesions. In
peripheral cementum, PC lesions were categorised by their shape on histological
cross sections of affected teeth into: flake-type, flask-like, or ellipsoid-shaped lesions
or combinations of these patterns. Bacteria from surface lesions penetrated between
Sharpey’s fibers of cementum in a direction perpendicular to the peripheral aspect of
the tooth, destroying the intrinsic fibres and Sharpey’s fibers. Bacteria also
penetrated in a direction parallel to the peripheral aspect of the tooth, undermining
the intrinsic fibres, including at the level of incremental growth lines. Bacteria were
also found in ellipsoid-shaped lesions and in cemental lacunae of affected cementum.
In dentine affected by PC, bacteria were found within and between damaged dentinal
tubules, sometimes causing flake-type lesions similar to those seen in cementum.
Bacteria penetrated primary dentine and/or (regular/irregular) secondary dentine
from the occlusal surface, or entered primary dentine through cementum and enamel
from the peripheral aspect. Dental plaque containing bacteria were sometimes
observed in dentinal fissure fractures.
PC of enamel was only visible using SEM, because this was the only method which
did not require prior decalcification, that almost completely removed enamel.
In conclusion, PC and IC are prevalent dental disorders in the examined British
equine population. The association between PC and concurrent dental disorders
(multiple concurrent dental disorders, diastemata/periodontal disease and dental
fractures), indicates that these should be addressed in affected horses. In horses
affected by IC, the focus should be on treatment of IC itself (like infundibular
fillings), because associations of IC were found with risk factors which cannot (or
not easily) be controlled such as age and region. Several bacteria could be identified
which were associated with PC and other bacteria were more associated with IC or
control groups. It was confirmed in the pathological study that bacteria penetrate the
cheek teeth affected by PC and IC. So the focus of treatment of PC and IC can also
be on reducing the bacteria associated with PC and IC respectively, or the focus
could be on prevention by making the teeth more resistant against caries by fluoride
treatment. A critical assessment of the use of chlorhexidine mouthwashes and
supplementation of fluoride are needed to evaluate its potential effects on PC and IC
Describing typeforms: a designer's response
No full textThe paper sets out an overview of a pragmatic research investigation initiated within a doctoral enquiry, and which continues to inform design practice and pedagogy. Located within the fields of typography and information design, and very much concerned with design history, enquiry emphasized exploration of alternative design research methodologies in the production of a design outcome loaded with pedagogical ambition.
The issue being addressed within the investigation was the limited scope of existing typeface classificatory systems to adequately describe the diversity of forms represented within current type design practice and thus, recent acquisitions to an established teaching collection in London.
Addressing this issue unexpectedly came to utilize the researcher’s own design practice as a methodology for managing emergent enquiry, and for organizing and generating new knowledge through the employment of visual information management methods.
A primary outcome of the enquiry was a new framework for the description of typeforms. This new framework will be described in terms of its operation, divergence from existing models and potential for application
Micro-CT and histological examination of accessory canals in 34 equine cheek teeth
No full textAccessory canals and apical deltas have been extensively studied in human dentistry. Their clinical role as a difficult to clean reservoir for bacteria during endodontic treatments has been well described. Many papers describe in detail the pulp anatomy of equine dentition but little attention has been given to their apical ramifications. The goal of this paper is to describe the presence and anatomy of these accessory canals and apical deltas in healthy equine cheek teeth and discuss their possible relevance in the light of equine endodontics. To accomplish this, 15 maxillary and 19 mandibular healthy cheek teeth were collected ranging from Triadan 06 s to 11 s with eruption ages from 4 to 9 years. Their root anatomy was documented in detail based on micro computed tomography images. A subset of 3 teeth also underwent histological examination. Accessory canals were found in all but two teeth examined. Up to 44 accessory canals per tooth have been found with locations ranging from the root furcation down to the apex of the root and with highly variable diameters. Apical deltas in different stages of development were found in 84% of the roots. The presence of accessory canals identified on microCT images could be confirmed using histological examination although some of them were obliterated by reparative dentin. Accessory canals can be found in most equine cheek teeth and add complexity to their endodontic anatomy. This could have important implications for their treatment in case of pulp pathology. In humans, failure to remove bacterial biofilm from such canals has been associated with failure of endodontic treatment. Research on diseased equine teeth is required to gain a better understanding of their clinical relevance in horses
Phonological Word and Grammatical Word: a cross-linguistic typology
No full text'Word' is a cornerstone for the understanding of every language. It is a pronounceable phonological unit. It will also have a meaning, and a grammatical characterization - a morphological structure and a syntactic function. And it will be an entry in a dictionary and an orthographic item. 'Word' has 'psychological reality' for speakers, enabling them to talk about the meaning of a word, its appropriateness for use in a certain social context, and so on. This volume is about 'word' in its many guises. It is a logical progression from our earlier volume Word: A Cross-linguistic Typology, edited by R. M. W. Dixon and Alexandra Y. Aikhenvald (Cambridge: Cambridge University Press, 2002), incorporating new facts, new insights, and new generalizations.
The volume starts with a typological introduction summarizing the main issues to do with 'word', with special focus on phonological and grammatical word and on their interactions. It is followed by revised versions of papers presented at the International Workshop "'Word": its manifestations and functions' organized by the editors and held at the Language and Culture Research Centre, James Cook University, 3-4 October 2018. An earlier version of Chapter 1 was circulated to the contributors, with a list of issues to be addressed, so as to ensure that the studies of individual languages within this volume were cast in terms of a common set of parameters. This is the tenth monograph in the series Explorations in Linguistic Typology, devoted to volumes from International Workshops organized by the Language and Culture Research Centre and its predecessors.
The Workshop and subsequent discussions between the editors and the authors were intellectually stimulating, with cross-fertilization of ideas and scholarly debate. Each author has undertaken intensive fieldwork and has firsthand in-depth knowledge of their languages, in addition to experience of working on linguistic typology, historical and comparative linguistics, and language contact and areal diffusion. The analysis is uniformly cast in terms of basic linguistic theory-the cumulative typological framework which provides the foundation for sound empirically-based descriptive and analytic works. We avoid formalisms (which provide restatements rather than explanations, and come and go with such frequency that any statement made in terms of them is likely to soon become inaccessible)
Gingival Fibrosarcoma in a Horse:A Case Report
No full textA 4-year-old thoroughbred cross mare was referred to the University of Edinburgh Veterinary School Equine Hospital for treatment of a soft tissue tumor on the buccal gingival margin of the rostral right maxillary cheek teeth. The lesion was initially surgically excised and diagnosed as a fibrosarcoma via histopathology. Adjunctive treatment with intralesional cisplatin chemotherapy was begun. The tumor recurred and was repeatedly treated with intralesional cisplatin injections and additional surgical resection over the course of 14 weeks. Despite the initial poor response to treatment, no further regrowth of the tumor occurred 3 months following its final treatment. The horse remained free of visible evidence of tumor nearly 5 years later
Surgery of the Paranasal Sinuses: Surgical Removal of the Cheek Teeth and Management of Orosinus Fistulae
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