What is the Difference Between Cementocytes and Osteocytes

The key difference between cementocytes and osteocytes is that cementocytes are cells arising from the cementoblast around the root of the teeth, while osteocytes are embedded in a fully formed bony matrix and help in bone remodelling.

A tooth consists of enamel, dentin, cementum, and pulp tissue. Cementum is a bone-like structure and a thin layer that covers the roots of teeth of mammals. It is made up of a layer of cementum-producing cells known as cementoblasts. The cells of the cementum that are entrapped in the lacunae are known as cementocytes. Bone is a mineralized connective tissue that contains osteoblasts. Bone tissue is remodelled throughout with bone cells, which aid in bone resorption and formation by osteoblasts. Osteocytes act as orchestrators and mechanosensors in the process of bone remodelling.

CONTENTS

1. Overview and Key Difference
2. What are Cementocytes 
3. What are Osteocytes
4. Similarities – Cementocytes and Osteocytes
5. Cementocytes vs Osteocytes in Tabular Form
6. Summary – Cementocytes vs Osteocytes

What are Cementocytes?

Cementocytes are cementoblasts enclosed in a self-generated matrix. Cementoblast is a cell that originates from follicular cells around the root of the tooth, and its function is cementogenesis. Cementocytes reside in a mineralized extracellular matrix of the cellular cementum.

Cementoblasts are similar to bone-forming osteoblasts, but they differ functionally and histologically. The cells of the cementum are the entrapped cementoblasts which are known as cementocytes. Each cementocyte lies in its lacuna. These lacunae consist of canaliculi or canals. However, these canaliculi do not contain nerves. Moreover, they do not radiate outward. They orient toward the periodontal ligament and contain cementocytic processes to diffuse nutrients from the ligament since it is highly vascularized. The progenitor cells present in periodontal ligaments contribute to the mineralization of tissues. After mineralization, cementoblasts lose their secretory activity and become cementocytes. Cementocytes play an important role in the regulation of cellular cementum formation and resorption.

What are Osteocytes?

An osteocyte is a cell that lies within the substance of a fully formed bone. It occupies a small chamber called a lacuna, and it is located in a calcified matrix of bone. Osteocytes originate from osteoblasts, and they are surrounded by secreted products. Cytoplasmic processes present in osteocytes extend away from the cell and toward other osteocytes through canaliculi. These canaliculi transport nutrients and waste products to maintain the viability of the osteocyte.

Osteocytes are very important since they are the most abundant type of cells present in mature bone tissues. They have a long life span, so they survive as long as the respective bone exists. Osteocytes have the ability for bone deposition and resorption. They are also involved in bone remodelling by the transmission of signals to other osteocytes, even for a minor deformation of bone. This makes the bone stronger if additional stress is applied to the bone. Osteocytes aid in the calcium removal from bones if the body’s calcium level drops below normal. The premature death or dysfunction of osteocytes is associated with diseases such as osteoarthritis and osteoporosis.

What are the Similarities Between Cementocytes and Osteocytes?

• Cementocytes and osteocytes reside in a mineralized extracellular matrix.
• They lie in lacunae.
• Both contain canaliculi.
• Moreover, both take part in the formation and resorption.

What is the Difference Between Cementocytes and Osteocytes?

Cementocytes are cells arising from the cementoblast around the root of the teeth, while osteocytes are embedded in a fully formed bony matrix and help in bone remodelling. Thus, this is the key difference between cementocytes and osteocytes. Besides, cementocytes arise from cementoblasts, while osteocytes arise from osteoblasts. Moreover, cementocytes are found in the tooth root, and osteocytes are found in all bones within the body.

The below infographic presents the differences between cementocytes and osteocytes in tabular form for side by side comparison.

Summary – Cementocytes vs Osteocytes

Cementocytes are cementoblasts enclosed in a self-generated matrix. Cementoblast is a cell that originates from follicular cells around the root of the tooth. Meanwhile, an osteocyte is a cell that lies within the substance of a fully formed bone. It occupies a small chamber called a lacuna, and it is located in a calcified matrix of bone. Cementocytes are found in the tooth root, and osteocytes are found in all bones within the body. The key difference between cementocytes and osteocytes is that cementocytes are embedded in a self-generated matric, whereas osteocytes are embedded in a fully formed bony matrix.

Reference

1. “Cementum.” An Overview | ScienceDirect Topics.
2. “Osteocyte.” Encyclopædia Britannica, Encyclopædia Britannica, Inc.

Image Courtesy:

1. “Human tooth diagram-en” By KDS4444 – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “Transverse section of bone en” By Source digital bitmap graphics: BDBRecreated in vector format: Nyq – Original analog graphics: Gray’s Anatomy of the Human Body from the classic 1918 publication available online at Bartleby.com.Digital bitmap graphics: Transverse Section Of Bone.pngRecreated in vector format: Own work (CC BY-SA 4.0) via Commons Wikimedia