Endodontic preparation.
Basic concepts .
1st class of the endodontic preparation series.
Definitions Basic concepts Sequence of endodontic preparation Means of preparation Objectives of endodontic preparation Basics of endodontic preparation Pulpectomy Penetration Disinfectant Apical limit of preparation Exploration Patency Radiographic odontometry Apical locators
in: in: Siqueira et al. Biological principles of endodontic treatment. of teeth with necrotic pulp and periradicular injury. Rev. bras. odontol., Rio de Janeiro, v. 69, n. 1, p. 8-14, jan./jun. 2012
Introduction: Introduction: The three clinical conditions that the professional deals with in day-to-day endodontic practice and that require intervention include teeth with irreversible pulpitis (biopulpectomy), with pulp necrosis and infection (necropulpectomy) and retreatment cases (26). The success of endodontic treatment depends on recognizing the idiosyncrasies of each of these three conditions. The fundamental difference between them lies in the fact that necrotic pulp and retreatment cases are characterized by the presence of infection, while vital pulp cases are infection-free. In order to achieve a high success rate of similar magnitude for these three conditions, it must be recognized that different therapeutic measures must be instituted. In other words, the treatment for these conditions must be based on different strategies if the same success rate is to be expected.
Effect of Chemical-Mechanical Preparation During the chemical-mechanical preparation, endodontic instruments promote the mechanical removal of microorganisms, their products and degenerated tissues, aided by a chemical substance that, besides maximizing the removal of debris through the mechanical action of flow and reflux, can also exert a significant chemical effect, provided that it has antimicrobial action and organic matter solvent. The mechanical action of instrumentation and irrigation is capable of substantially reducing the amount of microorganisms and degenerated tissue inside the root canal system.
However, the use of irrigating solutions (auxiliary chemical substances) with antibacterial activity significantly increases the efficacy of the preparation in terms of infection control. NaOCl is the auxiliary chemical substance most often used in endodontic treatment of teeth with pulp necrosis, in concentrations ranging from 0.5 to 6%. Studies show that there is no significant difference between different concentrations of NaOCl in terms of intracanal bacterial reduction and organic matter solvent capacity. Thus, regular exchanges of the solution in the canal and copious irrigations maintain the properties of the solutions inside the canal, compensating for the effects of concentration.
Apical Instrumentation Size Studies have revealed that the apical size of the preparation can have a significant influence on infection control. SIQUEIRA et al. revealed that with each sequential change of instruments to a larger gauge, the reduction of the bacterial population was significantly greater when compared to the previous file. This finding indicates that the larger the canal preparation, the greater the elimination of bacteria from its interior, which was corroborated by ROLLISON et al.
In clinical practice, the final diameter of the canal preparation will depend on the type of instrument used for preparation, the root volume and the presence of curvatures. Rotary and hand instruments made from a NiTi alloy can widen curved canals to diameters that are difficult to achieve with stainless steel instruments, with a much lower risk of trans-operative accidents. Sufficiently wide preparations can incorporate anatomical irregularities and allow substantial removal of irritants from within the root canal system. Furthermore, wide preparations allow better irrigation of the apical third of the canals.
Endodontic preparation. Basic concepts.
