4. Cementum cells

The following are the major cell types associated with cementum:

Cementoblasts
Cementocytes
Periodontal ligament fibroblasts
Odontoclasts (cementoclasts)

Fig. 101:  Transmission electron micrograph of cementoblast (CB) in periodontal ligament (PDL), adjacent to root cementum (C).  Cementoblasts initially originate from ectomesenchymal cells in the dental follicle.  Later in life, cementoblasts may arise from undifferentiated cells in the periodontal ligament.   Cementoblasts are morpholgically similar to fibroblasts.  However, they are located in close proximity to the cemental surface and frequently extend cytoplasmic processes (CP) toward the cementum.  They produce the intrinsic collagen fibers and ground substance which, together with the extrinsic fibers constitute the bulk of the cementum.  Active cementoblasts, like this one, have a well-developed rough-surfaced endoplasmic reticulum and Golgi region.         

Fig. 102:  Transmission electron micrograph of cementocyte (CC) within a lacuna (L) imbedded in cellular, mixed fiber cementum (CMFC).  During periods of rapid cementogenesis, cementoblasts may become trapped as cementocytes within lacunae. Cytoplasmic processes extend toward cementum surface through canaliculi in the cementum.  Cementocytes have a markedly reduced cytoplasmic volume and diminished number of cytoplasmic organelles, features that reflect a marked decrease in metabolic activity.               

Periodontal fibroblasts: Although technically part of the periodontal ligament, they produce collagen fibers that become mineralized, as they become incorporated into cementum. Therefore, periodontal ligament fibroblasts contribute to cementogenesis and are considered as cementum cells.

Odontoclasts (Cementoclasts): These multinucleated giant cells play an active role in cemental resorption.  They are indistinguishable from osteoclasts.

University of Pennsylvania and Temple University © 1999. All rights reserved. Created: May 8, 1999  Revised: URL: Max A. Listgarten: Comments to author: max@listgarten.com (Technical Support: TU Department of Dental Informatics: Heiko Spallek)