Head and neck nerves

1. The Role of Dental
Calculus and Other
Local Predisposing
Factors
‫دنان‬ ‫أوس‬ ‫الدكتور‬ ‫المدرس‬
‫اللثة‬ ‫أمراض‬ ‫أستاذ‬
IUST

2. Introduction
The primary cause of gingival inflammation
is bacterial plaque.
Other predisposing factors include calculus,
faulty restorations, complications associated with
orthodontic therapy, self-inflicted injuries, and
the use of tobacco.

3. • Calculus consists of mineralized bacterial
plaque that forms on the surfaces of natural
teeth and dental prostheses.
• Supragingival calculus is located coronal to
the gingival margin and therefore is visible in
the oral cavity. It is usually white or whitish
yellow in color; hard, with a claylike
consistency; and easily detached from the
tooth surface. After removal, it may rapidly
recur, especially in the lingual area of the
mandibular incisors.
• The color is influenced by contact with
substances such as tobacco and food
pigments. It may be localized on a single tooth
or group of teeth, or it may be generalized
throughout the mouth.
• The two most common locations for the
development of supragingival calculus are the
buccal surfaces of the maxillary molars and
the lingual surfaces of the mandibular anterior
teeth.

5. • Subgingival calculus is located below the
crest of the marginal
gingiva and therefore is not visible on
routine clinical examination.
The location and the extent of subgingival
calculus may be evaluated by careful tactile
perception with a delicate dental instrument
such as an explorer.
• Subgingival calculus is typically hard and
dense; it frequently appears to be
dark brown or greenish black in color, and it
is firmly attached to the tooth surface.
• Supragingival calculus and subgingival
calculus generally occur together, but
one may be present without the other.
• Microscopic studies demonstrate that
deposits of subgingival calculus usually
extend nearly to the base of periodontal
pockets in individuals with chronic
periodontitis but do not reach the junctional
epithelium.
• When the gingival tissues recede,
subgingival calculus becomes
exposed and is therefore reclassified as
supragingival.
Thus, supragingival calculus can be
composed of both the initial
supragingival calculus and previous
subgingival calculus.
Courtesy of Mr. A. Alhijani / IUST

9. • Both supragingival calculus and
subgingival calculus may be
seen on radiographs.
• Highly calcified interproximal
calculus deposits are freely
detectable as radiopaque
projections that protrude into the
interdental spaces. However, the
sensitivity level of detecting calculus
by radiographs is varying.
• The location of calculus does not
indicate the bottom of the
periodontal pocket, because the
most apical plaque is not sufficiently
calcified to be visible on
radiographs.

10. Courtesy of Mr. A. Alhijani / IUST

11. • Constitute (70% to 90%).
• The major inorganic proportions of calculus are approximately 76%
calcium phosphate (Ca3[PO4]2), 3% calcium carbonate (CaCO3), 4%
magnesium phosphate (Mg3[PO4]2), 2% carbon dioxide, and traces
of other elements such as sodium, zinc, strontium, bromine, copper,
manganese, tungsten, gold, aluminum, silicon, iron, and
fluorine.
• The percentage of inorganic constituents in calculus is
similar to that of other calcified tissues of the body.
• Dental calculus, salivary duct calculus, and calcified dental tissues
are similar in inorganic composition.

12. • The organic component of calculus consists of a mixture of protein–
polysaccharide complexes, desquamated epithelial cells, leukocytes,
and various types of microorganisms.
• Between 2% and 9% of the organic component is carbohydrate.
• The ratio of calcium to phosphate is higher in subgingival calculus,
and the sodium content increases with the depth of periodontal pockets.
• These altered compositions may be attributed to fact that the origin of
subgingival calculus is plasma, whereas supragingival calculus is
partially composed of salivary constituents.
• Salivary proteins present in supragingival calculus are not found in
subgingival calculus.

13. • Differences in the manner in which calculus is attached to the tooth
surface affect the relative ease or difficulty encountered during its
removal.
• Four modes of attachment have been described:
(1) Attachment by means of an organic pellicle on cementum and enamel,
(2) Mechanical locking into surface irregularities, such as caries lesions or
resorption lacunae,
(3) Close adaptation of the undersurface of calculus to depressions or
gently oblique hills of the unaltered cementum,
(4) Penetration of bacterial calculus into cementum.

14. • Calculus is mineralized dental plaque. The soft plaque is hardened by
the precipitation of mineral salts, which usually starts between the
1st and 14th days of plaque formation.
• Calcification has been reported to occur within as little as 4 to 8 hours.
• Calcifying plaques may become 50% mineralized in 2 days and 60% to
90% mineralized in 12 days.
• All plaque does not necessarily undergo calcification. Early plaque
contains a small amount of inorganic material, which increases as the
plaque develops into calculus.
• Microorganisms are not always essential in calculus formation, because
calculus freely occurs in germ-free rodents.
• The calcium concentration or content in plaque is 2 to 20 times higher
than in saliva.

15. The theoretical mechanisms by which plaque becomes mineralized can be
stratified into two categories:
1. Mineral precipitation results from a local rise in the degree of overload of
calcium and phosphate ions.
2. Seeding agents induce small foci of calcification that enlarge and merge
to form a calcified mass.

16. • Distinguishing between the effects of calculus and plaque on the
gingiva is difficult, because calculus is always covered with a
non-mineralized layer of plaque.
• A positive correlation between the presence of calculus and the
prevalence of gingivitis exists, but this correlation is not as great as that
between plaque and gingivitis.
• The initiation of periodontal disease in young people is
closely related to plaque accumulation, whereas calculus accumulation is
more prevalent in the chronic form of periodontitis found in older adults.
• The incidence of calculus, gingivitis, and periodontal disease
increases with age.
• Calculus does not contribute directly to gingival inflammation,
but it provides a fixed focal point for the continued accumulation of
bacterial plaque and its retention in close proximity to the gingiva.

17. • Periodontal pathogens such as Aggregatibacter
actinomycetemcomitans, Porphyromonas gingivalis, and Treponema
denticola have been found within the structural channels and
gaps of supragingival and subgingival calculus.
• Subgingival calculus is likely to be the product rather than the
cause of periodontal pockets. Plaque initiates gingival inflammation,
which leads to pocket formation, and the pocket in turn provides a
sheltered area for plaque and bacterial
accumulation.
• The increased flow of gingival crevicular fluid
associated with gingival inflammation provides the minerals that
mineralize the continually accumulating plaque, resulting in the
formation of subgingival calculus.

18. • Although the bacterial plaque that coats the teeth is the main
etiologic factor in the development of periodontal disease, the
removal of subgingival plaque and calculus constitutes the
cornerstone of periodontal therapy.
• Calculus plays an important role in maintaining and highlighting
periodontal disease by (1) keeping plaque in close contact with the
gingival tissue and by (2) creating areas where plaque removal is
impossible. Therefore, the clinician must not only possess the clinical
skill to remove the plaque and calculus, but he or she must also be very
careful about performing this task.