Dental caries

 

Causes of dental caries

Dental caries occur as a result of the pathogenic effect of microbial "dental" plaque on the tooth enamel. Time and three conditions are necessary for the occurrence and development of dental caries:

• presence of cariogenic microflora
• intake with food and retention of easily digestible carbohydrates on the surface of the tooth enamel
• reduction of caries resistance (resistance to cariogenic factors)

 

Classification of dental caries

According to Black, the following classes of carious cavities are distinguished:

1. Class 1 carious tooth cavity - cavities located in the fossae and fissures on the chewing surface of molars and premolars, the lingual surface of the upper incisors, and in the vestibular and lingual grooves of molars associated with the chewing surface.
2. Class 2 carious tooth cavity - cavities at the contacts (approximal) surfaces of molars and premolars.
3. Class 3 carious tooth cavity - cavities on the contact (approximal) surfaces of the incisors and canines, which do not require removal and restoration of the incisal edge.
4. Class 4 carious tooth cavity - cavities on the contact surfaces of the incisors and canines, which require restoration of the incisal edge.
5. Class 5 carious tooth cavity - cavities in the cervical region of all groups of teeth.
6. Class 6 carious tooth cavity - cavities at the incisal edge of the anterior and at the tops of the cusps of the posterior teeth.

 

Tooth caries stages

Topographic classification provides for four stages of dental caries:

• caries in the spot stage - focal demineralization of the enamel without the formation of a cavity
• superficial caries - a carious cavity within the enamel
• medium caries - carious cavity within the enamel and superficial layers of dentin
• deep caries - carious cavity within the enamel and peri-pulpal dentin

 

Treatment of dental caries

Treatment of dental caries consists of the following stages:

• preparation of carious tooth cavity
• tooth filling
• dressings and temporary tooth fillings
• tooth spacers
• medicated tooth pads

 

Dissection of carious tooth cavity

Opening a carious tooth cavity - this stage consists of removing all overhanging and undermined edges of the enamel to obtain (create) sheer walls. The purpose of this stage is to provide access for further manipulations and a good view of the cavity.

Expansion of the carious cavity (prophylactic expansion) of the tooth - preventive expansion - a continuation of the stage of opening the carious cavity. Its purpose is to prevent the "recurrence" of caries. At this stage, the final outer outline of the cavity is created.

Necrectomy (necrotomy, "removal of caries") of the tooth - this stage involves the complete removal of softened and pigmented dentin from the carious cavity.

If this operation is performed poorly, then next to the filling after a while the development of carious lesions will be observed ("continuing", "recurrent" caries). If the infected dentin is not removed from the bottom of the carious cavity, pulpitis may develop.

Formation of a carious tooth cavity - the goal of this stage is to give the carious cavity a shape that provides the filled tooth with sufficient stability, resistance to functional stress and contributes to the strong retention of the filling. At this stage, the final shape of the cavity is created.

 

Tooth filling

The purpose of filling with dental caries is to restore the anatomical shape, appearance, and function of the tooth, to prevent further development ("recurrence") of caries.

Requirements for an "ideal" filling material for dental caries were formulated at the end of the last century by Miller and remain relevant to this day.

Filling (restorative) material for dental caries should:

• be chemically resistant (does not dissolve under the influence of saliva, liquid food, oral and dentinal fluid)
• be mechanically strong, since during the chewing process there are significant loads (30-70 kg)
• be resistant to abrasion
• fit snugly against the walls of the cavity (adaptation to the walls)
• this means micromechanical retention or chemical bonding of material with tooth tissues and other materials (adhesion)
• maintain its shape and volume for a long time, prevent shrinkage, ensure spatial stability of the filling for a long time
• be minimally dependent on moisture during the filling and curing process
• be harmless to the tissues of the tooth, the mucous membrane of the mouth, and the body as a whole (biocompatibility of the filling material)
• match in appearance to natural teeth
• have low thermal conductivity to prevent thermal irritation of the pulp
• have a coefficient of thermal expansion similar to the coefficient of thermal expansion of tooth tissues
• have good handling properties: sufficient plasticity, easy to insert into the cavity, not stick to instruments, etc.
• be radiopaque
• have anti-caries action
• have a long shelf life, do not require special storage and transportation conditions

Although modern materials allow one to come close to solving many of these problems, so far there has not been created an ideal material that meets all of the listed requirements for dental caries. Therefore, dentists are forced to combine various materials, simultaneously apply 2-3 layers, and sometimes 4 different materials into the formed cavity, taking into account the nature (depth and location) of the cavity, the negative and positive properties of the materials used, and the individual characteristics of the caries course in this patient.

Modern filling materials for dental caries are divided into the following groups:

• materials for dressings and temporary tooth fillings
• materials for medical pads (linings)
• materials for isolating tooth spacers (linings)
• materials for permanent tooth fillings
• materials for filling (filling) the root canals of the tooth

 

Dressings and temporary tooth fillings

The main requirements for filling materials of this group are as follows:

• ensure a tight closure of the tooth cavity
• have sufficient compressive strength
• to be indifferent to the pulp, tooth tissues, and medicinal substances
• easy to insert and remove from the cavity
• do not dissolve in oral fluid and saliva
• do not contain components that violate the adhesion and hardening processes of permanent filling materials

The bandages are applied for 1-14 days. As dressings used: artificial dentin, dentin paste, zinc oxide eugenol types of cement, vinoxol, gutta-percha.

Temporary fillings are designed for several months (usually up to six months). Most often used for this purpose: zinc-eugenol, zinc-phosphate, sometimes - polycarboxylate, or glass ionomer cement.

 

Insulating tooth pads

Most modern permanent filling materials have an adverse effect on the pulp of the tooth. Therefore, between the permanent filling and the bottom of the carious cavity (especially if the cavity is within the dentin), there should be a gasket that performs several functions.

This gasket (lining) must meet some requirements:

• provide long-term protection of dentin and tooth pulp from chemical, thermal and galvanic effects, prevent hypersensitivity after preparation and filling
• withstand mechanical stress associated with the redistribution of chewing pressure
• improve the retention of permanent fillings
• easy to insert into the cavity, quickly harden and form a stronger bond with the tooth tissues than with permanent filling material, so that in the event of shrinkage of the latter, there is no separation of the gasket from the bottom of the cavity
• have an anti-carious effect, have a remineralizing effect on the underlying dentin
• have no toxic effect on the pulp
• do not disturb the properties of the permanent restoration material
• the pad should not be destroyed by gingival and dentinal fluids

 

Therapeutic tooth pads

The basic principle of modern dentistry is a gentle attitude to tooth tissues. Removal of the pulp should be avoided in cases where pathological changes in it are reversible and its preservation is possible. In such situations, a healing pharmacological effect on the pulp is necessary, which, by stopping the inflammatory process, would prevent its further spread, and stimulate the healing process. To solve these problems, medicinal pads are used. They contain active substances for various purposes.

Materials for treatment pads should:

• have anti-inflammatory, antimicrobial, odontotropic action
• do not irritate the tooth pulp
• provide a strong sealing of the underlying dentin, connection with tooth tissues, interlining and permanent filling materials
• correspond to the physical and mechanical properties of permanent filling materials

Healing pads are indicated in the following clinical situations with dental caries:

• deep caries treatment
• biological treatment of acute focal pulpitis
• conservative treatment for the accidental opening of the tooth cavity (traumatic pulpitis)

Methods for the treatment of dental caries, aimed at preserving the viability of the inflamed pulp and restoring its function, involve various methods of pharmacological action. Treatment of dental caries in such cases is carried out in two stages:

• Stage 1 of dental caries treatment - relief of the inflammatory process in the pulp, impact on the microflora, reduction of pain. For this purpose, drugs are used that have a strong, but short-term effect. They are usually applied for several days as a medical bandage.
• Stage 2 of dental caries treatment - stimulation of the formation of replacement dentin, normalization of metabolic dentin in the dental pulp.

At this stage of the treatment of dental caries, drugs are used that have a long, "mild" effect, which does not decompose during a prolonged stay in the carious cavity. They are applied in the form of a medical pad under temporary or permanent fillings. In the treatment of deep dental caries, as a rule, they are limited to the imposition of a medical pad with a long-term odontotropic and antiseptic effect.