Calculus And Other Plaque Retentive Factors

Calculus and Other Plaque Retentive Factors

Question 1: Define calculus. Describe the different types of calculus and its composition.
Answer:

Dental calculus is defined as the mineralized form of bacterial plaque. Although it was once presumed that mechanical irritation of soft tissue by calculus deposits played a role in etiopathogenesis of periodontal disease, it is now recognized that its primary role is as a plaque retentive factor.

Classification Of Calculus

Calculus is classified on the basis of its location and mineral origin as follows:

1. Supragingival or salivary calculus.
2. Subgingival or serumal calculus.

Read And Learn More: Periodontology Important Question And Answers

Supragingival Calculus (Salivary Calculus)

It is primarily located coronal to the gingival margin as a yellow-white mass that varies in consistency from being a soft mass to hard flakes. It is found most frequently on the buccal surfaces of maxillary posteriors and lingual surfaces of mandibular interiors as these areas lie in close proximity to the salivary gland duct openings—parotid and submandibular.

Subgingival Calculus (Serumal Calculus)

• This is present apical to the gingival margin, often detectable only on probing. It is usually dense, darker in color, and tends to be strongly attached to the root surface.
• Mineralization of this calculus may be predominantly from crevicular fluids and blood products and hence the name Perumal calculus.

Composition Of Calculus

Although the composition of calculus is highly variable, four different crystals of calcium phosphate have been described: brushite 9%, octacalcium phosphate 21%, whitlockite 21%, and hydroxyapatite 58%.

• Subgingival calculus has been reported to exhibit more whitlockite and less brushite and octacalcium phosphate.
• The whitlockite in subgingival calculus also contains small amounts of magnesium.
• The organic component of calculus consists of protein polysaccharide complexes, PMNs, and microorganisms.
• Salivary proteins and lipids also form some portion of the organic component.

Question 2: Describe the theories of calculus formation.
Answer:

Calculus forms as a mineralization phenomenon that results from precipitation of mineral salts from saliva, blood, and crevicular fluid. It starts in the first few hours of plaque formation but may take as long as two weeks for complete mineralization.

• The organic content of plaque is gradually replaced by calcium-containing crystals that bind to protein polysaccharide complexes of plaque.

Booster Mechanism Theory

• According to this theory, calcification occurs as a result of high pH and high calcium and phosphorus concentration leading to their precipitation.
• The rise in pH and the increased levels of calcium and phosphorus are governed by local metabolic factors.

Epitaxic Theory

• This theory suggests that calculus is formed by the coalescence of several smaller foci of calcification or seeds.
• The initial crystal or seed is formed when a proper organic matrix is available and the process has been called heterogeneous nucleation.
• Potential seeds of foci that have been suggested include calcium, phospholipid, phosphate complexes, and bacteria.

Inhibition Theory

• According to this theory, calculus is formed not due to increase in calcium-phosphate levels but due to the absence of inhibiting agents such as pyrophosphate.
• Consequently, in areas where there is a deficiency of this inhibiting factor, calculus formation occurs.

Transformation Theory

• According to this theory, amorphous deposits are transformed into crystalline forms without epitaxy or nucleation.
• Other mechanisms including bacteria have been suggested to play a role.

Question 3: Describe the plaque retentive factors.
Answer:

• Several other factors may favor plaque accumulation and thereby contribute to the etiopathogenesis of periodontal disease.
• The important among them are; tooth anatomic factors and iatrogenic factors.

Tooth Anatomic Factors

• Developmental anomalies in teeth that favor plaque retention may lead to progression of periodontal disease.
• The important among them are root concavities, bifurcation ridges, palatogingival grooves (Figure 11.2), and cervical enamel projections.
• All of these deformities contribute to plaque accumulation as they provide ecological niches where bacteria can multiply without being dislodged.

latrogenic Factors

Iatrogenic factors are defined as physician induced factors which lead to periodontal disease. Almost any restorative, prosthetic or orthodontic appliance that is improperly designed may contribute to the etiopathogenesis of periodontal disease.

Question 4: Describe various iatrogenic factors that may lead to periodontal disease.
Answer:

The more common factors involved in restorative dentistry that contribute to the etiology of periodontal disease may be classified under as follows:

Material of the Restoration

• Auto-curing acrylic may pose both chemical injury as well as act as a local factor attractant.
• These are not used too often these days and therefore the resultant damage has been somewhat reduced.
• Even so, caution must be exercised in the use of these resins during fabrication of temporary and interim prostheses.

Surface Roughness

• All restorations need to have a highly polished surface as rough surfaces tend to attract plaque more often than smooth ones.
• Care must be taken especially in the proximal areas as they are sometimes inaccessible and the problem is compounded as the tissues in this region are also vulnerable to injury.

Margins

Overhanging margins or restoration can form a nidus for the accumulation of plaque. In general, subgingival margins may contribute more to plaque accumulation, change the microflora and lead to periodontal disease.

Contacts and Contours

The interproximal contour of restorations is important as over-contoured restorations decrease the size of the interdental embrasure, making self-cleansing difficult. On the other hand, under contoured crowns may lead to open contact, food impaction, and periodontal disease.

Occlusion

Improperly designed occlusive forces may lead to formation of plunger cusps, high points that may cause primary trauma from occlusion.

Iatrogenic Factors in Orthodontics

• Fixed orthodontic appliances such as brackets and molar bands may serve as a nidus for plaque accumulation if proper oral hygiene procedures are not instituted.
• Orthodontic forces, if delivered injudiciously may also result in periodontal injury.

Conclusion

All plaque retentive factors have a major influence on the etiopathogenesis of periodontal disease and have to be eliminated as part of the phase I or etiotropic phase of therapy.