Classification of atypical cavities
Topic 38: «Features of preparation and filling and destroyed devital tooth cavities. Parapulpar and intracanal pins and construction. Their views, value in restoring the anatomical tooth form and function».
Classification of atypical cavities.
1. Caries of cement (cavity located below the gum line), the gum pulls back with pressure bandage of dentin or coagulated. Remaining steps are performed by common rules.
2. Secondary caries - previously filling of the tooth completely removed and carious cavity is formed by the general rules again.
3. Circular caries - cavity formed around the circumference of the tooth in compliance with the transition rules to the bottom of the cavity to wall at a right angle. Create additional incisions with wheel-shaped drill.
4. When combined lesions of type II and V, III and V classes by Black must be available to form cavity by common rules.
5. Caries tuber of chewing teeth - creates a cavity type II class with additional platform or without depending on the focus and filling material. Or cavities localized on the cutting edges of the incisors and canines.
6. In pulpless teeth with considerable destruction of the crown for better fixation of fillings we using anchor pins, which are fixed in the canals, with the fill of pre-apical 1/3 length of canal.
In the presence of atypical cavities preparation comes to combining the elements of particular classes (e.g., circular cavities dissected as Vth class by Black, the combination of II and V classes cavities are not output to the chewing surface). In the presence of I and II classes at a tooth cavity, localized on the chewing surface, can serve as an additional platform for cavity located on the proximal surface.
Preparation of the atypical cavity dissected with further filling of the cavity. The main feature of the preparation is the most restrictive the approach to the removal of caries. Drills should be used, the size of which just a little more than the diameter of the cavity. Otherwise it will be removed excess amount of hard tissue of the tuber or cutting edge of the tooth, which would weaken the area on which a maximum load for biting and chewing.
Features of preparation of the atypical cavities.It needs the gentlest preparation. The optimal depth of the cavity can be 1,5 mm, if there is no need for deep preparation. Ability to save of enamel, dentin to be deprived, which is associated with a considerable thickness of the enamel layer, especially in the cusp tip molars. The edge of the enamel should not dissect in the form of rebate. At preparing the oral atypical recommended to create a form that resembles simply a box shaped cavity of I class, corners are usually not form, due to the small volume of the cavity.
Preparation of the vital teeth must be very gentle with air water cooling, with the principles of biological expediency and modern techniques of preparation.
Preparation of pulpless teeth is accompanied by almost no pain and usually does not cause negative emotional reactions by patients even with large volumes of preparation.
During extracting of the pulp with a sterile fissure drill opening is expanding and over pulp arch removed. For extensiveness of the intervention, there are two points of view. Some dentists recommend removing all overhanging edge of dentin, so that the walls of the defect and the carious tooth cavity are a common line. With this method of preparation is opened free access to the root canal, but it there is a considerable weakening of the tooth crown.
Other authors suggest sparing preparation, in which the overhanging edge of dentin removed. This allows you to keep the stability of the crown, but the extraction of the pulp from the pulp chamber and the root canal of a very difficult.
In practice using both methods of preparation. If necessary, create a pulpectomy free access to the root canal, if necessary pulpectomy cavity partially dissected.