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==Introduction==
See [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|anatomy and physiology of the teeth]]
==Functional Anatomy==
*The [[Cavity & Gingiva - Pathology|gingival crevice]] is an important site for disease processes in mouth to begin.
*In ruminants and rodents [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|teeth]] may fail to oppose properly or to allow side to side movement of jaws. This produces uneven wear (especially in horse). Sharp edges are produced on the outside of the [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|teeth]] in the upper jaw and inside of the [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|teeth]] in the lower jaw, which causes painful feeding and inanition (not eating).
**Approximately 75% of wasting horses have dental abnormalities.
*This is not a problem in carnivores as do they not use [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|teeth]] for [[Mastication|mastication]].
*If a [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|teeth]] is lost the opposing [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|teeth]] may become very long and stop mouth closing properly.
**Seen mostly in rodents - [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|teeth]] may even penetrate through [[Lips - Anatomy & Physiology|lip]].
==Defence Mechanisms==
==Developmental Pathology==
===Erythropoietic Porphyria.===
*"Congenital Pink [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|Tooth]]"
*Occurs in cattle, cats and sometimes pigs
*[[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|Teeth]] are pink due to congenital inability to metabolise haemoglobin pigments. These pigments also produce [[photosensitivity]] in skin.
*This results in severe sunburn if animal exposed to normal levels of sunlight.
Discoloration of a single [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|tooth]] is more likely to be caused by pus in the [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|tooth]].
===Photosensitising agents===
*Phenothiazine which was used as an anthelmintic
*Tetracycline - if one injects bitches with tetracycline when pregnant, puppies are born with brown [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|teeth]], which fluoresce under UV light.
*Haemosiderin may also produce pinky / brown colour to [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|teeth]] usually due to damage and haemorrhage into [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|tooth]].
===Abnormal Wear of Teeth===
*Abnormal wear of [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|teeth]] in herbivores may result from irregular grinding of molars as well as from periodontal disease.
*Sharp edges usually form on the lingual aspect of the mandibular [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|teeth]] and the buccal aspects of the maxillary molars and may cause quite severe oral lacerations.
**The condition is sometimes known as “'''shear mouth'''”.
*Malocclusion of [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|teeth]] may be acquired as a result of trauma and loss or displacement of [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|teeth]].
*It is particularly important in those teeth which continue to grow excessive growth, interference with prehension of food or even growth of the [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|tooth]] into adjacent structures.
*Malocclusions in dogs and cats may arise from retention of deciduous [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|teeth]] in the young animal.
*Malocclusion of [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|teeth]] may also occur as a result of malformations of the jaws. The terminology used for these is rather confusing and the following should assist:
**'''Prognathism''' is an abnormally long lower jaw.
**A similar effect is produced by '''brachygnathia superior''' (ie short maxilla). Both conditions may be referred to as ''undershot jaw''.
***A typical breed affected is the '''Boxer'''.
**'''Retrognathism''' is an unusually short lower jaw. This may also be called '''brachygnathia inferior''' (i.e. short mandible). The condition is referred to as ''overshot jaw'' or ''parrot mouth''.
***Typical breeds affected are the '''Borzoi''' or '''Rough Collie'''.
===Abnormal Numbers of Teeth===
*Abnormal numbers of [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|teeth]] can vary from total lack (anodontia), to too few (oligodontia), to increased numbers (polyodontia).
[[Image:oligodontia.gif|right|thumb|75px|<small><center>Oligodentia (Courtesy of Alun Williams (RVC))</center></small>]]
==Infection of teeth==
===Dental caries===
*Only really seen in primates, but may be seen in horse caused by bacterial decalcification of [[Enamel|enamel]].
*Acid producing organisms enter dentine and underun enamel.
*Infection may spread to [[Pulp|pulp]] cavity.
[[Image:toothinfection.gif|right|thumb|125px|<small><center>Stages of tooth infection (Courtesy of Alun Williams (RVC))</center></small>]]
===Infundibular Impaction===
*Seen in the ruminant and horse.
*Food material impacted in infundibulum undergoes bacterial fermentation and results in enzymic damage to [[Enamel|enamel]] and [[Dentine|dentine]].
===Direct infection of pulp cavity===
*For example, a dog whose canine has been snapped off while biting stones etc. exposes [[Pulp|pulp]].
*Also possible that infection in [[Pulp|pulp]] cavity originates from a circulating pyaemia producing pulpitis.
===Gingival crevice inflammation===
*Mostly in carnivores (also cats), may occur in horses.
*[[Gingiva - Anatomy & Physiology|Gingival]] inflammation starts because of dental calculus (tartar) from diets high in minerals and diets consisting of soft rather than hard crunchy food.
*Dental plaque becomes calcified and whole [[Crown|crown]] may become covered in brown chalky material.
*Calculus gives brittle dirty brown covering to [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|tooth]].
*This may not affect [[Enamel|enamel]] at all but may produce mild [[Cavity & Gingiva - Pathology|gingivitis]] round edge and the gum may start to recede.
*This exposes more of [[Crown|crown]], may reach level of [[Dentine|dentine]] and infection may enter the alveolus and loosen ligaments holding [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|tooth]] in and ultimately the [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|tooth]] will become loose and fall out.
*Pyorrhoea is unusual in sheep but, nonetheless, periodontal disease with “broken mouth” is a major cause of culling of ageing ewes.
===Alveolar Periostitis===
*A more virulent infection into the alveolus produces alveolar periostitis.
*Infection spreads from [[Pulp|pulp]] or from gingivitis to produce the periostitis.
*This may then break out of the alveolus into the bone causing [[Bones Inflammatory - Pathology#Osteomyelitis|osteomyelitis]].
**Seen in infection of carnassial teeth in dogs as chronic sinus discharging below eye. So called 'malar' abscess.
*Only treated by removal of [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|tooth]].
*Abscess may break through into maxillary sinus. If drained will get recovery.
**Other maxillary cheek [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|teeth]] can be involved in pyaemic infection with sinus formation.
*Hard to evaluate on [[Skull and Facial Muscles - Anatomy & Physiology#Mandible (mandibula)|mandible]], may produce fistula that also needs [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|tooth]] removal.
==Granulomatous and pyogranulomatous Inflammation==
===Mandibular Osteomyelitis===
[[Image:Lumpyjaw1.gif|right|thumb|125px|<small><center>Lesion caused by Actinomyces Bovis(Courtesy of Alun Williams (RVC))</center></small>]]
*"Lumpy jaw"
====Clinical====
*Seen mainly in cattle and exotics caused by [[Actinomycetes|''Actinomyces bovis'']] producing [[Bones Inflammatory - Pathology#Osteomyelitis|osteomyelitis]] of mandible.
*Mostly young animals.
*Will not heal without treatment and jaw enlarges until animal cannot eat.
====Pathogenesis====
*Starts as alveolar periostitis of lower cheek [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|teeth]], due to ingestion of poor coarse roughage e.g. straw or hay with lots of thistles.
*Slowly enlarging [[Skull and Facial Muscles - Anatomy & Physiology#Mandible (mandibula)|mandible]] (occasionally [[Skull and Facial Muscles - Anatomy & Physiology#Maxilla|maxilla]]) due to granulomatous inflammation producing much fibrous tissue.
*No real pus formation but "'''sulphur granules'''" in middle of lesion.
*Organism causes "'''pyogenic granuloma'''."
*Can grow to enormous size (e.g. size of grapefruit) and whole of mandible is blown apart by multiple foci of infection.
<small>Also see:[[Oral Cavity - Tongue#Actinobacillosis|Actinobacillosis - "Wooden Tongue" (Courtesy of Alun Williams (RVC))</small>]]
====Pathology====
3 major features:
#Inflammatory removal of bone. As cortex of bone is pushed out by central inflammation produces thinning of bone cortex with proliferation of new periosteal bone. The centre of the [[Skull and Facial Muscles - Anatomy & Physiology#Mandible (mandibula)|mandible]] is eroded forming a honeycomb-like bone. Eventually will erode through bone producing [[Granuloma|granulomatous]] lesion on bottom of [[Skull and Facial Muscles - Anatomy & Physiology#Mandible (mandibula)|mandible]] and eventually eroding through skin.
#Granuloma with micro abscess's in centre with greenish / yellow granules in middle of pus. These granules known as "sulphur bodies". Sulphur body is a colony of tangled mass of Actinomyces filaments. This is surrounded by [[neutrophil]]s and [[macrophage]]s forming a pyogenic granuloma.
#Masses of fibrous tissue surround the granuloma and fill the spaces where bone has been destroyed.
===Odontoclastic resorptive lesions===
*Cats
**Odontoclasts attack external and internal to the [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|tooth]].
**Initially start at the neck/cervical region and extend into [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|tooth]] [[Root|root]] and also enter the [[Root|root]] via the apical foramen (stage 3 lesions)
**20%+ of cats have them
**Different from caries – demineralization by bacteria fermenting CHO on the [[Enamel|enamel]].
**ORLs – only occur when odontoclasts resorb the [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|tooth]]/bone
***continues with remodeling of [[Alveolar bone|alveolar bone]] until ankylosis
*** fixation of [[Periodontal ligament|periodontal ligament]] and [[Lamina dura|lamina dura]] so that the [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|tooth]] is permanently fixed to the bone.
*Odontoclasts normally only active in young animals to resorb the [[Tooth Development - Anatomy & Physiology#Temporary Tooth|deciduous teeth]] to make way for the [[Tooth Development - Anatomy & Physiology#Permanent Tooth|permanent teeth]] – so represents abnormal activation in adults.
*Can have inflammatory infiltrates into the resportive lesions
==Eosinophilic Inflammation==
==Necrotizing Inflammation==
==Lymphocytic and plasmacytic Inflammation==
==Proliferative Pathology==
===Hyperplastic===
====Focal fibrous hyperplasia<ref name="epulides1"> </ref>====
*44% of cases.
*Dense collagenous tissue, with ulceration/superficial inflammation
*Dystrophic calcificaition within the fibrous connective tissue stroma (often highly cellular, with 'young stellate fibroblasts'
*No odontogenic epithelium seen.
*Occasional strands of surface epithelium growing down into the stroma.
*Most of these were previously diagnosed as fibromatous or ossifying epulides.
===Neoplastic===
====Peripheral odontogenic fibroma<ref name="epulides1">J Comp. Path. 1992 (106), 169-182 The Histological Nature of Epulides in Dogs F. J. M. Verstraete*, A. J. Ligthelmf and A. WeberT. ... review of 154 oral 'epulis' from dogs reviewed with the current (at the time) human literature.</ref>====
[[Image:epulis.gif|right|thumb|125px|<small><center>Canine Epulis (Courtesy of Alun Williams (RVC))</center></small>]]
*aka: Fibromatous epulis of periodontal ligament origin
*17% of cases.
*Proliferation of fibrous tissue with variety of osteoid, [[Cementum|cementum]] or [[Dentine|dentine]]-like material.
*Isolated strands or islands of odontogenic epithelium always present (ie: suggesting induction of connective tissue by the epithelial cells).
*The stroma contains neoplastic fibroblasts, with varying cellularity.
*The overlying epitheluim is normal.
====Peripheral ameloblastoma<ref name="epulides1"> </ref>====
[[Image:ameloblastoma.gif|right|thumb|125px|<small><center>Ameloblastoma (Courtesy of Alun Williams (RVC))</center></small>]]
*aka: basal cell carcinoma, acanthomatous ameloblastoma, acanthomatous epulis
*18% of cases.
*Islands and sheets of mature odontogenic epithelium within a collagenous fibrous connective tissue stroma of low/moderate cellularity.
*Each of the islands bounded by a row of tall columnnar cells.
*These palisading cells exhibit polarisation away from the basement membrane and had cytoplasmic vacuolation.
*Central cells had a basaloid appearance.
*Often infiiltrating into the underlying bone.
*Synonymous with basal cell carcinoma.
====Central ameloblastoma<ref name="epulides1"> </ref>====
*Different from peripheral ameloblastoma - cystic changes and follicular arrangement of ameloblasts and stellate reticulum cells, resembling the basic structure of the [[Tooth Anatomy - Anatomy & Physiology|enamel organ]].
==Degenerative Pathology==
===Odontodystrophy===
*Damage to [[Ameloblasts|ameloblasts]] (which form [[Enamel|enamel]]) in utero upsets permanent incisor formation.
*[[Enamel]] is marked by pits, lines etc.
====In ruminants:====
*Damage to [[Enamel|enamel]] formation most often caused by fluoride poisoning.
*Seen in cattle grazing on pasture contaminated by cement works effluent.
*Chalky mottling and yellow brown pitting of [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|tooth]].
====In canines:====
[[Image:enamal-hypoplasia.gif|right|thumb|125px|<small>Enamal Hypoplasia Following a CDV infection (Courtesy of Alun Williams (RVC))<center></center></small>]]
Very severe systemic disease early in life / or in utero may result in severe discoloration or pitting of [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|teeth]] due to effect on [[Enamel|enamel]] formation. (e.g. [[Paramyxoviridae#Canine Distemper Virus (CDV)|distemper in dog]])
==Metabolic Pathology==
==Nutritiona Pathology==
==Traumatic Pathology==
==Vascular Pathology==
==References==
<small>
With thanks to Andrew Jefferies (Cambridge) and Alun Williams (RVC) for providing access to their lecture materials
<references/>
</small>
==Learning Tools==
[[Alimentary Flashcards - Pathology#Teeth Flashcards|Teeth Flashcards]]