tailieunhanh - Mechanical preparation of root canals: shaping goals, techniques and means

When a root tip encounters an obstacle that resists penetration, the root cap becomes less pointed and the surface cells may slough off (Souty, 1987). Mechanical impedance decreases the rate of root elongation because of both a decrease in the rate of cell division in the meristem, and a decrease in cell length (rather than volume). Eavis (1967) found a decrease of 40% in the cell division rate at a root penetration resistance ( MPa) sufficient to decrease the root elongation rate by 70%. Cell length is decreased and the volume of the inner cortical cells may. | Endodontic Topics 2005 10 30-76 All rights reserved Copyright Blackwell Munksgaard ENDODONTIC TOPICS 2005 1601-1538 Mechanical preparation of root canals shaping goals techniques and means MICHAEL HULSMANN OVE A. PETERS PAUL . DUMMER Preparation of root canal systems includes both enlargement and shaping of the complex endodontic space together with its disinfection. A variety of instruments and techniques have been developed and described for this critical stage of root canal treatment. Although many reports on root canal preparation can be found in the literature definitive scientific evidence on the quality and clinical appropriateness of different instruments and techniques remains elusive. To a large extent this is because of methodological problems making comparisons among different investigations difficult if not impossible. The first section of this paper discusses the main problems with the methodology of research relating to root canal preparation while the remaining section critically reviews current endodontic instruments and shaping techniques. Introduction Preparation of the root canal system is recognized as being one of the most important stages in root canal treatment 1 2 . It includes the removal of vital and necrotic tissues from the root canal system along with infected root dentine and in cases of retreatment the removal of metallic and non-metallic obstacles. It aims to prepare the canal space to facilitate disinfection by irrigants and medicaments. Thus canal preparation is the essential phase that eliminates infection. Prevention of reinfection is then achieved through the provision of a fluid-tight root canal filling and a coronal restoration. Although mechanical preparation and chemical disinfection cannot be considered separately and are commonly referred to as chemomechanical or biomechanical preparation the following review is intended to focus on the mechanical aspects of canal preparation cavity. Chemical disinfection by means of .

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