A NOTE ON DENTAL CALCULUS

Dental calculus

For the periodontal diseases:

•     The primary etiologic factor is: Is the dental plaque.
•       The associated factor: is the dental calculus, it helps in new formation of the plaque.
•       The modifying factor: is a systemic disease, it aggravates the disease when the plaque is presents.

 Calculus:

•    Is a mineralized dental plaque that occurs in the tooth surfaces & dental prosthesis, it has many forms:
•    Bridging over the gingival margin.
•     Follow the festooning shape of the dentition.
•     Lobular form.
•     In case of malalignment :àprotected area for the plaque à calculus

 Classification:

             Supragingival                  &               subgingival calculus..

         Generally: both can occur together or one may appear alone.

Subgingival calculus: 

•      Gingival fluid origin.
•       Below the crest of the gingival margin.
•       Hard, dark& flint like.
•       Greenish black or dark brown in color.
•       Firmly attached to the tooth, can’t be seen and detected by explorer No.621 probe.
•       Extent nearly to the base of the pocket in chronic periodntitis, but doesn’t reach the Junctional epithelium.

 Supragingival calculus:    

•     Saliva origin.
•    Coronal to the gingival margin. Can be composed of supra &sub gingival calculus.
•    Hard, clay like consistency, White, white yellowish in color& its color may be affected by the tobacco or food stain.
•     Easy to be seen in the oral cavity, may be generalized or localized.
•     Easy to be removed &usually recurrent especially in the: Lower incisors. 

• Most common location :near to the orifices of the S. glands’ ducts

Parotid gland’s duct ”stenson”----->opposite to buccal surface of maxillary molars.

Submandibular “bartholine” & sublingual “wharton” ducts ----->Lingual surface of lower incisors.

it’s shape : either covers the occlusal surfaces or  bridge like structure over interdental papilla.

                                                Calculus contents:

Inorganic contents:70-90%		Organic contents
2/3 of the calculus inorganic component is in crystalline form ;there are  4 types of crystals . The crystals are: hydroxyappatite ,58% à magnesium white locate,21%  àmost in post octacalcium phosphate,12% Brushite, 9% àmost in mandibular anteriors. Detected more frequently in supragingival calculus. Constitute the bulk. Generally 2 or more crystals are detected in the calculus. Incidence of 4 crystals à varies with age of calculus.		Mixture of  : Protein-poly saccharide complex + desquamated host cells (leukocytes & host cells) + microorganisms. Carbohydrates (1.9-9.1%): Glucose , glactose   ,mannose ,arabinose ,rhamnose glucoric acid ,glactouric acid glucoseamine & glactose amine. à all are present in saliva except : Rhaminose  &  arabinose . Salivary proteins (5.9-8.2%): Most are amino acids. lipids 0.2%:nutral fat ,fatty acids ,cholesterol ester, phospholipids & cholesterol.
*Contents:	The differences     Supra gingival calculus	Between: Sub gingival calculus
hydroxyappatite: Ca Ph : Mg white: brushite: ratio of Ca/Ph: sodium contents: salivary proteins:	Equal.   More. Less. More. Low.   Increase with the depth of PD pocket. Yes	Equal Less. More Less. Higher. No.

Calculocementum:

Is the calculus has morphological appearance similar to cementum. This is because the calculus is interdigitates the cementum & no differences between them.

Mode of attachment of the calculus to the tooth surface:

• Close adaptation under surface depression.
• In sub gingival calculus.
• By organic pellicle (very weak)
• Penetration of the bacteria to the cementum.
• Mechanical interlocking to the surface irregularities: resorption lacuna or caries, in the cementum by sharpies fibers.                          

Calculus formation:

Calculus is the dental plaque that undergoes mineralization.

Calcification starts                      4-8 hrs   after plaque.

50 % become mineralized after   2 days.

60-90                                          12 days.

• Plaque can be daily removed at home by brushing but the calculus is
• not ,it is only removed clinically by the dentist .

• Calculus formation à the bacterial action will stopped (adv) but it will act as stagnation area for new plaque accumulationà (protection for plaque). 

• Early plaque contains small amount of inorganic material but it will increase as the plaque develops into calculus. 

• All plaque doesn’t necessarily undergo calcification.

• It reaches a plateau of maximal mineral by 2 days.

• Microorganisms are not always essential in calculus formation. 

• Plaque has ability to conc. The Ca at  2-20 times it’s level in saliva. 

• There is a suggestion that Ph is more critical than Ca in plaque mineralization.

• Early plaque of heavy former àmore Ca ,3 times Ph &less K than non calculus former.