Cementicle

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A cementicle is a small, spherical or ovoid calcified mass embedded within or attached to the cementum layer on the root surface of a tooth, or lying free within the periodontal ligament.{{cite book|author=Chiego Jr. DJ|title=Essentials of Oral Histology and Embryology: A Clinical Approach|url=https://books.google.com/books?id=LMrsAwAAQBAJ&pg=PA133|date=14 April 2014|publisher=Elsevier Health Sciences|isbn=978-0-323-29100-2|page=133}}{{cite book|author1=Fehrenbach MJ|author2=Popowics T|title=Illustrated Dental Embryology, Histology, and Anatomy|url=https://shop.elsevier.com/books/illustrated-dental-embryology-histology-and-anatomy/fehrenbach/978-0-443-10424-4|edition=2026|publisher=Elsevier|isbn=9780443104244|page=196}} They tend to occur in senior population.

There are 3 types:

• Free cementicle – not attached to cementum{{cite book|author1=Ghom A|author2=Mhaske S|title=Textbook of Oral Pathology|url=https://books.google.com/books?id=yKqgUT4OAokC&pg=PA122|date=17 September 2010|publisher=Jaypee Brothers Publishers|isbn=978-81-8448-402-1|page=122}}
• Attached (sessile) cementicle – attached to the cementum surface (also termed exocementosis)
• Embedded (interstitial) cementicle – with advancing age the cementum thickens,{{cite book|author=Kumar GS|title=Orban's Oral Histology & Embryology|url=https://books.google.com/books?id=061EAwAAQBAJ&pg=PA196|date=10 February 2014|publisher=Elsevier Health Sciences APAC|isbn=978-81-312-3801-1|page=196}} and the cementicle may become incorporated into the cementum layer

They may be visible on a radiograph (x-ray). They may appear singly or in groups, and are most commonly found at the tip of the root. Their size is variable, but generally they are small (about 0.2 mm{{cite book|author=Chatterjee K|title=Essentials of Oral Histology|url=https://books.google.com/books?id=1_ge-OtrElQC&pg=PA112|date=1 December 2006|publisher=Jaypee Brothers Publishers|isbn=978-81-8061-865-9|page=112}} – 0.3 mm in diameter).

Cementicles are usually acellular, and may contain either fibrillar or afibrillar cementum, or a mixture of both. Cementicles are the result of dystrophic calcification, but the reason why this takes place is unclear. Cementicles are thought to form when calcification occurs around a nidus, a precipitating center. Around this nidus they slowly enlarge by further deposition of calcium salts. Examples of how cementicles are thought to form include:

• Calcification due to degenerative changes in the epithelial cell rests of Malassez
• Calcification of thrombosed (blocked) capillaries in the periodontal ligament (i.e. a phlebolith)
• Microtrauma to Sharpey's fibres causes small spicules of cementum or alveolar bone to splinter into the periodontal membrane{{cite book|author=Mosby|title=Mosby's Dental Dictionary|url=https://books.google.com/books?id=hQejBQAAQBAJ&pg=PA115|date=1 August 2013|publisher=Elsevier Health Sciences|isbn=978-0-323-10013-7|page=115}} Some do not consider these as true cementicles.