Odontoclasts attack external and internal to the [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|tooth]]. Initially they start at the neck/cervical region and extend into [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|tooth]] [[Root - Anatomy & Physiology|root]] and also enter the root via the apical foramen (stage 3 lesions).
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**20%+ of cats have them
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FORLs are different from caries – demineralization by bacteria fermenting CHO on the [[Enamel - Anatomy & Physiology|enamel]].
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Odontoclasts normally only active in young animals to resorb the [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology#Temporary Tooth|deciduous teeth]] to make way for the [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology#Permanent Tooth|permanent teeth]] – so represents abnormal activation in adults.
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Additionally there may also be inflammatory infiltrates into the resportive lesions.