Differences between Fenestration and Dehiscence

Fenestration and Dehiscence are two similar conditions of Tooth which are similar due to bone loss around the tooth but are different by the type of bone loss or bone surrounding it. To understand the differences first let us know about What is Fenestration and What Dehiscence:

Definition of Tooth Fenestration:

Fenestration are Isolated areas in which root is denuded of bone and root surface is covered only by periosteum and overlying gingiva is called as fenestration. Make a note that Marginal Bone is intact in Fenestration

It is a localized defect in the alveolar bone which exposes the apical or medium third of the root surface but does not involve the alevolar margin. 

Definition of Tooth Dehiscence:

Dehiscence are isolated areas in which root is denuded of bone and root surface is covered by periosteum and overlying gingiva but the denuded are extends through the Marginal Bone.

In Dehiscence there is no bone on one side of it (coronally) and is measured with the use of graduated periodontal probe. The loss of  bone is at least 4 mm apical to the margin of the inter-proximal bone. 

Difference between Fenestration and Dehiscence:

The only and main difference is that

• Fenestration the “Marginal Bone is Intact”
• Dehiscence the “Denuded areas extend through the Marginal Bone”

Common Features of Dehiscence and Fenestration:

1. Dehiscence and Fenestration occur approximately in 20% of teeth:
2. More common on the Facial bone than on the Lingual Bone
3. More common in the Anterior teeth than on the posterior teeth
4. Mostly Bilateral

Predisposing factors of Dehiscence and Fenestration:

• Prominent root contours
• Malpositioning of teeth
• Labial protrusion of root
• Thin bony plates

Classification of Fenestration:

Fenestration is classified based on their apicocoronal location in relation to the root length. It is divided into four types – 

1. Bone loss is seen at the level of the apical third of the dental root seen in 48.5% of the cases, all these are seen in maxilla
2. Bone loss is seen at the level of the middle third of the dental root which is 28% of all cases and seen in both Maxilla and Mandible
3. Bone loss is seen at the coronal third of the root which is 19% of all cases and is seen in mandible
4. Bone  loss extends from the apical to the middle third of the root which is 4.3% of all cases with all seen in Maxilla

The causes for Fenestration and Dehiscence is not known and the etiology is usually mentioned as unknown. Both Fenestration and Dehiscence cannot be identified clinically or radiographically and are only seen during surgery or by probing in case of dehiscence.