Bone Loss And Patterns Of Bone Destruction Question And Answers

Bone Loss and Patterns of Bone Destruction

Bone destruction in periodontal disease is a result of gingival inflammation and/or trauma from occlusion.

Question 1: What are the pathways for the spread of gingival inflammation?
Answer:

The spread of gingival inflammation is perhaps an important controlling actor that influences the pattern of bone loss as well as its extent and severity.

Gingival inflammation can spread via.

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1. Transseptal fibers into the bone along the vessel channel that course throughout the alveolar bone and perforate the crest of the interdental septum. The inflammation may thus enter the center of the crest or through its side depending upon the course of the vessel channel. After reaching the bone, the inflammation may again return to the periodontal ligament.
2. The inflammation can spread directly from the gingiva into the periodontal ligament and from there on to the interdental septum.
3. The outer periosteal surface also provides less physical resistance to the spread of inflammation and inflammation may thus spread lingually or facially along this surface and penetrate into the marrow spaces by coursing along the supra periosteal vascular network.

Question 2: Write a note on the rate of bone loss.
Answer:

The rate of bone loss is dependent on the imbalance between formation and destruction. Even in advanced bone loss, formation of bone always seems to occur, only it does not keep pace.

• In most of the population, there is a rate of attachment loss less than 0.09 mm annually. In the more susceptible group, this rate may increase up to 0.5 mm annually.

Periods of Destruction

• All periodontal destruction is intermittent and episodic with periods of active exacerbation and relative quiescence which is usually of a longer duration.
• The active destruction is a result of conversion from a T-lymphocyte to a B lymphocyte predominant lesion or a more aggressive subgingival flora.

Question 3: Describe the mechanism of bone destruction.
Answer:

Normal bone homeostasis is maintained by osteoblast-osteoclast coupling mechanism. This coupling is disturbed due to excessive osteoclastic activity as a result of.

1. Direct effect of plaque products on the osteoclast.
2. Effect of plaque products on gingival fibroblast and immune cells, which in turn release pro-inflammatory mediators.
3. Pro-inflammatory mediators such as IL-1, IL-6, PGE2, TNF-α, and lipopolysaccharides influence gingival fibroblast, osteoblasts, and T-cells to release RANKL which binds to RANK on the osteoclast thus, activating osteoclastogenesis.
4. Bone loss caused by trauma from occlusion is modified by the presence or absence of inflammation. In the presence of inflammation, the bone loss tends to be faster and vertical in nature.

Question 4: Discuss the patterns of bone loss.
Answer:

Osseous defect may be broadly classified into horizontal and vertical bone loss.

• Horizontal bone loss is most common form of bone loss in periodontal disease and is associated with chronic Periodontitis. In this pattern, the labial, lingual, and interdental bone is lost at almost the same rate.
• Vertical defects (Figure 19.1) are commonly associated with aggressive periodontitis, food impaction, and trauma from occlusion.
• It can be subclassified into one walled (Figure 19.2), two walled (Figure 19.3) or three walled defects (Figure 19.4) on the basis of the number of remaining alveolar bone walls.
• Prognostically the 3-walled defects have the best prognosis as they respond well to regenerative therapy.

Hemiseptum

These are vertical defect with only wall of alveolar bone present and are present in the interdental area. It is usually associated with a poor prognosis.

Osseous Craters

Concavities in the interdental crest that are bounded within the facial and lingual walls are called osseous craters.

• The interdental area is susceptible to injury as there is increased tendency for food accumulation in an anatomically vulnerable area that is lined by non-keratinized epithelium.

Reversed Architecture

Normal alveolar bone architecture is reserved in these cases as a result of which the interdental bone is at a more apical position when compared to the radicular bone.

• Buttressing bone formation may be observed on the facial aspect. Usually occurs as an adaptive remodeling to occlusal forces.

Furcation Involvement

Furcation involvements are osseous defects that occur between the roots of multirooted teeth because of the pathological resorption of the alveolar bone between the roots.

Question 5: What are the factors influencing bone loss?
Answer:

1. Anatomic factors: Presence of dehiscence and fenestration may affect bone loss pattern. The root anatomy, position, angulation may affect the alveolar shelf and influence the bone loss patterns.
2. Food impaction: As described previously this could lead to vertical bone loss.
3. Type of periodontitis: Aggressive periodontitis favors vertical bone loss while chronic periodontitis tends to exhibit horizontal bone loss.
4. Trauma from occlusion: It tends to change plaque induced inflammatory change such that horizontal bone loss becomes vertical in nature.

Conclusion

Bone loss is perhaps the single most-important factor that affcts the morbidity associated with periodontitis. Regenerating lost bone has been the focus of clinicians and researchers for last several decades with varying degrees of success.