What is the Difference Between Cellular and Acellular Cementum?

The main difference between cellular and acellular cementum lies in their structure, location, and function. Here are the key differences:

1. Location: Cellular cementum is relatively thick and covers the apical half of the root, while acellular cementum is relatively thin and covers the cervical half of the root.
2. Cellular Composition: Cellular cementum consists of cells, such as cementocytes, while acellular cementum does not contain cells.
3. Fiber Content: Cementum contains two types of fibers: extrinsic (Sharpey's) fibers, which are embedded ends of the principal fibers, and intrinsic fibers, which are fibers of cementum proper. Cellular cementum contains both intrinsic and extrinsic fibers, while acellular cementum primarily contains extrinsic fibers.
4. Formation: Acellular cementum is formed initially, and cellular cementum is formed after. The majority of cellular cementum forms after the tooth reaches the occlusal surface, while the majority of acellular cementum forms before the tooth reaches the occlusal plane.
5. Function: Cellular cementum serves as the medium of attachment for collagen fibers to the alveolar bone, providing a strong connection between the tooth and the surrounding bone. Acellular cementum, on the other hand, has a more adaptive function, filling in the space between the tooth and the alveolar bone.

Comparative Table: Cellular vs Acellular Cementum

The main difference between cellular and acellular cementum lies in their thickness, coverage, and cellular content. Here is a table comparing the two types of cementum:

Cellular cementum is responsible for minor repairs of resorption and deposition to maintain the root structure. It is the medium of attachment for collagen fibers to the alveolar bone and contains cells. On the other hand, acellular cementum does not contain cells and mainly serves an adaptive function. It is initially formed and covers the cervical half of the root, while cellular cementum is formed after and covers the apical half.