Dental caries – History, Classification and Causes

Dental caries is commonly called tooth decay. Caries in latin is called as ‘rot’ or ‘decay’ and Dental caries means ‘rotten or decayed teeth’.

Definition: Dental Caries is an irreversible microbial multifactorial disease of the calcified tissues of the teeth, characterized by de-mineralization of the inorganic portion and destruction of the organic substance of the tooth. (WHO definition)

History of Dental Caries:

Dental Caries has not been reported in our ancestors in the Pre Neolithic periods (12000 BC) and hence it is called as “Disease of modern civilization“. It is seen that first instance of Dental caries was reported in Skulls examined from Nelithic periods which is 12,000 to 3000 BC from Brachycephalic man.

Pithecanthropus or earliest known humans did not show any signs of Caries or carious teeth in the skull. This comes as period before 12,000 BC.

Carious teeth were seen more frequently in prehistoric man from 3000 to 750 BC.

Types Of Dental Caries

Classification of Dental Caries as given by GV Black

Classification of Dental caries:

Dental caries is basically divided into 4 types based on the surfaces they affect :

1. Smooth Surface Caries.
2. Pit and Fissure Caries.
3. Root Surface Caries
4. Deep Dentinal Caries

These were some basic organisms giving a brief account of the causative organisms but you can find the detailed account of the Causative Organisms of each type of Caries at Types of Caries and their Causative Organisms

It is the infection of the tooth which destroys the morphologic and sometimes the physiologic features of the tooth. It is most commonly caused by the acid producing commensal bacteria present in the mouth .

Examples of acid producing bacteria: Lactobacillus , Streptococcus Viridans (Str.Mutans)

The common causes of dental caries is the fermentation of the carbohydrates by the acid producing bacteria which make the environment acidic, this acidic environment damages the dentin and one commensal bacteria produce a adhesive agent (Dextrin) which binds the debris together and binds it to the tooth surface which ends up in Dental Plaque .

There are many classification for Dental caries , as it takes a whole lot of time to discuss we will talk about it later.  Dental caries affects all the Calcified parts of the tooth structures and there are different micro organisms which affect the respective parts :

1. Enamel – Streptococcus Mutans
2. Dentin – Lacto Bacillus
3. Cementum – Actinomycetes

These were some basic organisms giving a brief account of the causative organisms but you can find the detailed account of the Causative Organisms of each type of Caries at Types of Caries and their Causative Organisms

Carries Susceptibility based on type of Tooth:

• Upper and lower first molars: 95%
• Upper and lower second molars: 75%
• Upper second bicuspid or premolar: 45%
• Upper First bicuspid or premolar: 35%
• Lower second Bicuspid or premolar: 35%
• Upper central and lateral incisor: 30%
• Upper cuspid or canine and lower first bicuspid: 10%
• Lower central and lateral incisor: 3%
• Lower cuspids: 3%

Susceptible Tooth Surfaces to Caries:

In general Surface enamel is less susceptible or more resistant to dental caries when compared to subsurface enamel. The Surface enamel is high in mineral content like fluoride, zinc, lead and iron which help in preventing caries.

Hypoplastic Enamel, deep narrow occlusal fissures, buccal or lingual pits are predisposing factors to dental caries.

List of Susceptible tooth surfaces:

In normal tooth the saliva flow is continuous and tooth is bathed in saliva which helps in remineralizing the early carious lesion which is supersaturatd with Calcium and Phosphorus preventing extension of caries.

Attrition: Tooth surface or occlusal surfaces which are attrited loose the surface enamel and the subsurface enamel is exposed which is more prone to caries.

Rotated or malaligned tooth: Because of the odd position of the tooth, it makes it difficult to clean all the surfaces of the tooth leading to food impaction which leads to caries formation.

Low Saliva or Dry Mouth: In cases where there is decrease in saliva it leads to decrease in pH leading to demineralisation of enamel.