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Teeth - Pathology (view source)

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==Introduction==
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See [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|anatomy and physiology of the teeth]]
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==Functional Anatomy==
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*The [[Cavity & Gingiva - Pathology|gingival crevice]] is an important site for disease processes in mouth to begin.
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*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).
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**Approximately 75% of wasting horses have dental abnormalities.
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*This is not a problem in carnivores as do they not use [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|teeth]] for [[Mastication|mastication]].
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*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. 
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**Seen mostly in rodents - [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|teeth]] may even penetrate through [[Lips - Anatomy & Physiology|lip]].
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==Defence Mechanisms==
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==Developmental Pathology==
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===Erythropoietic Porphyria.===
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*"Congenital Pink [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|Tooth]]" 
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*Occurs in cattle, cats and sometimes pigs
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*[[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|Teeth]] are pink due to congenital inability to metabolise haemoglobin pigments. These pigments also produce [[photosensitivity]] in skin.
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*This results in severe sunburn if animal exposed to normal levels of sunlight.
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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]].
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===Photosensitising agents===
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*Phenothiazine which was used as an anthelmintic
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*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.
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*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]].
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===Abnormal Wear of Teeth===
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*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.
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*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.
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**The condition is sometimes known as “'''shear mouth'''”.
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*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]].
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*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.
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*Malocclusions in dogs and cats may arise from retention of deciduous [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|teeth]] in the young animal.
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*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:
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**'''Prognathism''' is an abnormally long lower jaw.
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**A similar effect is produced by '''brachygnathia superior''' (ie short maxilla). Both conditions may be referred to as ''undershot jaw''.
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***A typical breed affected is the '''Boxer'''.
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**'''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''.
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***Typical breeds affected are the '''Borzoi''' or '''Rough Collie'''.
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===Abnormal Numbers of Teeth===
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*Abnormal numbers of [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|teeth]] can vary from total lack (anodontia), to too few (oligodontia), to increased numbers (polyodontia).
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[[Image:oligodontia.gif|right|thumb|75px|<small><center>Oligodentia (Courtesy of Alun Williams (RVC))</center></small>]]
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==Infection of teeth==
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===Dental caries===
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*Only really seen in primates, but may be seen in horse caused by bacterial decalcification of [[Enamel|enamel]].
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*Acid producing organisms enter dentine and underun enamel.
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*Infection may spread to [[Pulp|pulp]] cavity.
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[[Image:toothinfection.gif|right|thumb|125px|<small><center>Stages of tooth infection (Courtesy of Alun Williams (RVC))</center></small>]]
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===Infundibular Impaction===
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*Seen in the ruminant and horse.
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*Food material impacted in infundibulum undergoes bacterial fermentation and results in enzymic damage to [[Enamel|enamel]] and [[Dentine|dentine]].
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===Direct infection of pulp cavity===
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*For example, a dog whose canine has been snapped off while biting stones etc. exposes [[Pulp|pulp]].
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*Also possible that infection in [[Pulp|pulp]] cavity originates from a circulating pyaemia producing pulpitis.
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===Gingival crevice inflammation===
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*Mostly in carnivores (also cats), may occur in horses. 
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*[[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.
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*Dental plaque becomes calcified and whole [[Crown|crown]] may become covered in brown chalky material.
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*Calculus gives brittle dirty brown covering to [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|tooth]].
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*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.
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*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.
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*Pyorrhoea is unusual in sheep but, nonetheless, periodontal disease with “broken mouth” is a major cause of culling of ageing ewes.
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===Alveolar Periostitis===
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*A more virulent infection into the alveolus produces alveolar periostitis.
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*Infection spreads from [[Pulp|pulp]] or from gingivitis to produce the periostitis.
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*This may then break out of the alveolus into the bone causing [[Bones Inflammatory - Pathology#Osteomyelitis|osteomyelitis]].
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**Seen in infection of carnassial teeth in dogs as chronic sinus discharging below eye. So called 'malar' abscess.
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*Only treated by removal of [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|tooth]].
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*Abscess may break through into maxillary sinus. If drained will get recovery.
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**Other maxillary cheek [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|teeth]] can be involved in pyaemic infection with sinus formation.
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*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.
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==Granulomatous and pyogranulomatous Inflammation==
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===Mandibular Osteomyelitis===
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[[Image:Lumpyjaw1.gif|right|thumb|125px|<small><center>Lesion caused by Actinomyces Bovis(Courtesy of Alun Williams (RVC))</center></small>]]
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*"Lumpy jaw"
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====Clinical====
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*Seen mainly in cattle and exotics caused by [[Actinomycetes|''Actinomyces bovis'']] producing [[Bones Inflammatory - Pathology#Osteomyelitis|osteomyelitis]] of mandible.
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*Mostly young animals.
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*Will not heal without treatment and jaw enlarges until animal cannot eat.
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====Pathogenesis====
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*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. 
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*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.
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*No real pus formation but "'''sulphur granules'''" in middle of lesion.
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*Organism causes "'''pyogenic granuloma'''."
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*Can grow to enormous size (e.g. size of grapefruit) and whole of mandible is blown apart by multiple foci of infection.
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<small>Also see:[[Oral Cavity - Tongue#Actinobacillosis|Actinobacillosis - "Wooden Tongue" (Courtesy of Alun Williams (RVC))</small>]]
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====Pathology====
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3 major features:
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#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.
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#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. 
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#Masses of fibrous tissue surround the granuloma and fill the spaces where bone has been destroyed.
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===Odontoclastic resorptive lesions===
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*Cats
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**Odontoclasts attack external and internal to the [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|tooth]].
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**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)
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**20%+ of cats have them
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**Different from caries – demineralization by bacteria fermenting CHO on the [[Enamel|enamel]].
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**ORLs – only occur when odontoclasts resorb the [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|tooth]]/bone
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***continues with remodeling of [[Alveolar bone|alveolar bone]] until ankylosis
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*** 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.
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*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.
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*Can have inflammatory infiltrates into the resportive lesions
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==Eosinophilic Inflammation==
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==Necrotizing Inflammation==
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==Lymphocytic and plasmacytic Inflammation==
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==Proliferative Pathology==
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===Hyperplastic===
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====Focal fibrous hyperplasia<ref name="epulides1"> </ref>====
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*44% of cases.
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*Dense collagenous tissue, with ulceration/superficial inflammation
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*Dystrophic calcificaition within the fibrous connective tissue stroma (often highly cellular, with 'young stellate fibroblasts'
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*No odontogenic epithelium seen.
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*Occasional strands of surface epithelium growing down into the stroma.
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*Most of these were previously diagnosed as fibromatous or ossifying epulides.
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===Neoplastic===
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====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>====
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[[Image:epulis.gif|right|thumb|125px|<small><center>Canine Epulis (Courtesy of Alun Williams (RVC))</center></small>]]
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*aka: Fibromatous epulis of periodontal ligament origin
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*17% of cases.
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*Proliferation of fibrous tissue with variety of osteoid, [[Cementum|cementum]] or [[Dentine|dentine]]-like material.
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*Isolated strands or islands of odontogenic epithelium always present (ie: suggesting induction of connective tissue by the epithelial cells).
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*The stroma contains neoplastic fibroblasts, with varying cellularity.
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*The overlying epitheluim is normal.
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====Peripheral ameloblastoma<ref name="epulides1"> </ref>====
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[[Image:ameloblastoma.gif|right|thumb|125px|<small><center>Ameloblastoma (Courtesy of Alun Williams (RVC))</center></small>]]
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*aka: basal cell carcinoma, acanthomatous ameloblastoma, acanthomatous epulis
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*18% of cases.
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*Islands and sheets of mature odontogenic epithelium within a collagenous fibrous connective tissue stroma of low/moderate cellularity.
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*Each of the islands bounded by a row of tall columnnar cells.
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*These palisading cells exhibit polarisation away from the basement membrane and had cytoplasmic vacuolation.
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*Central cells had a basaloid appearance.
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*Often infiiltrating into the underlying bone.
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*Synonymous with basal cell carcinoma.
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====Central ameloblastoma<ref name="epulides1"> </ref>====
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*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]].
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==Degenerative Pathology==
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===Odontodystrophy===
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*Damage to [[Ameloblasts|ameloblasts]] (which form [[Enamel|enamel]]) in utero upsets permanent incisor formation.
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*[[Enamel]] is marked by pits, lines etc.
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====In ruminants:====
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*Damage to [[Enamel|enamel]] formation most often caused by fluoride poisoning. 
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*Seen in cattle grazing on pasture contaminated by cement works effluent.
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*Chalky mottling and yellow brown pitting of [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|tooth]].
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====In canines:====
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[[Image:enamal-hypoplasia.gif|right|thumb|125px|<small>Enamal Hypoplasia Following a CDV infection (Courtesy of Alun Williams (RVC))<center></center></small>]]
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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]])
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==Metabolic Pathology==
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==Nutritiona Pathology==
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==Traumatic Pathology==
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==Vascular Pathology==
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==References==
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<small>
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With thanks to Andrew Jefferies (Cambridge) and Alun Williams (RVC) for providing access to their lecture materials
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<references/>
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</small>
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==Learning Tools==
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[[Alimentary Flashcards - Pathology#Teeth Flashcards|Teeth Flashcards]]
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