DENTAL CARIES

Man has suffered the effects of dental caries for centuries, and much study and research have been devoted to their causes and prevention. The disease is caused by a microbial process that starts on the surface of the teeth and leads to the breaking down of the enamel, dentin, and cementum, in some cases causing pulp exposure. This pathologic break that is produced on or in the tooth surface is called acarious lesion (fig. 5-4) or commonly called a cavity. The process that destroys the hard surfaces of the tooth is called decay.

Contributing Factors

The cause of tooth decay has been linked to a group of bacteria called streptococci and other acid producing bacteria that are in the oral cavity. Decalcification of the enamel, the first step in the decay process, is caused by:

Bacterial plaque adhering to the smooth surfaces of the teeth

Acid, produced by bacteria in food debris, being trapped in pits and fissures

Decay Process

Dental caries usually appear first as a chalky white spot on the enamel, which indicates the decalcification process. If proper oral hygiene is not maintained, the lesion may become stained and take on a dark appearance. In pit and fissure caries, the area of decalcification at the surface is normally small, and the white spot is less noticeable than in smooth surface caries. In either type of caries, the surface becomes roughened, as can be noted by passing a dental explorer point over it. If the tooth surface has an area that has not progressed past the decalcification stage, this type of carious lesion is called incipient. As the decay spreads in the enamel, it may stop. If this occurs, the process is called an arrested carious lesion (fig. 5-5). These areas in which dental caries have been arrested are dark and, in some instances, hollowed out. A dental explorer passed over or in these areas will feel hard to the touch. If the area still has active decay, the explorer may "sink in" the soft decay.

Dental caries can progress further into the dentin of the tooth, and spread out laterally widely undermining the enamel and dentin. If this occurs, often there may be no visible changes until extensive destruction has taken place. The condition of the caries if not arrested or restored with operative dentistry (filling) will spread through the dentin into the pulp of the tooth, thus requiring endodontic treatment (root canal).

Figure 5-4.\Carious lesions.

Figure 5-5.\Arrested caries.

RECURRENT CARIES

Recurrent caries are decay processes that occur underneath existing dental restorations. More simply stated, another cavity has occurred in the tooth where there was a filling or restoration. Some of the causes are as follows:

Improper cavity preparation\The dentist was unable to remove all of the decay in the tooth before the placement of a restoration.

Inadequate cavity restoration\Open margins (space in-between the restoration and tooth).

Old restorations\The margins of the restoration break down or are not completely sealed when originally placed, creating a "leaky margin."

TYPES OF CARIOUS LESIONS

Depending on its location, a carious lesion is designated as either a pit and fissure type or a smooth surface type. Pit and fissure caries develop in depressions of teeth surfaces that are hard to keep clean of food debris and plaque.

Smooth surface caries usually develop on the proximal surface (fig. 5-6) or the gingival third of facial and lingual surfaces on the teeth. These areas in-between (interproximal) the teeth are where plaque accumulate and form, starting the decay process.

DISEASES OF THE DENTAL PULP

The dental pulp is a living tissue. All living tissues can die or become diseased. The dental pulp is composed of vascular connective tissue encased in dentin, which provides protection. Even with this protection, the pulp may receive injuries by thermal changes, carious lesions from micro-organisms, and mechanical trauma. The extent of pulpal damage and the vitality (life) of the tooth depend on the severity of injury and how the pulp will react to disease. The term pulposis refers to any disease involving the dental pulp. Some of the more common diseases of the pulp are pulpalgia, pulpitis, periapical abscess, and necrosis, which are briefly explained next.

PULPALGIA

Pulpalgia refers to pain in the dental pulp, and commonly occurs after a restoration has been placed in a tooth. It can also be caused by root planing and periodontal surgery. The tooth may become sensitive to touch, temperature changes, and sweet or sour foods. Pain associated with pulpalgia has been described as short, sharp shooting pain that may increase when lying down or walking upstairs.

PULPITIS

Pulpitis is an inflammation of the dental pulp, usually caused by a bacterial infection resulting from

Figure 5-6.\Interproximal caries.

dental caries or fractured teeth. Pulpitis may be caused by other conditions, such as chemical irritants and thermal changes with materials used in dental restorations that can transmit heat or cold to the dental pulp. When micro-organisms enter the pulp, they start to produce severe damage, which leads to a buildup of pressure in the canal. The result of this pressure may cause a dull ache that can lead to a more severe, pulsating pain. When severe pulpitis occurs, the dentist may remove a portion or all of the pulp in an injured tooth.