6 Basic Steps In Rct.docx

6 Basic Steps in RCT I. II. III. IV. V. VI.

Access Cavity Preparation Pulp extirpation Root canal preparation Canal disinfection Obturation Final Restoration

Access Preparation Coronal Access Cavity Opening prepared on the crown of the tooth to allow adequate entry of instruments to the apex for root canal cleaning, preparation, and obturation  Most important phase of non-surgical RCT  Mandatory for optimum results  Instruments and materials are easier to handle in the canal Objective To provide a smooth, unobstructed channel from the orifice to the apex that allows the cleaning and shaping of the entire length and circumference of the canal while conserving tooth structure and maintaining the structural integrity of the tooth 1. Canal patency or straight-line access o Put the instruments down to the radiographic length 2. To locate all RC orifices o CEJ o Dentinal Map 3. To conserve sound tooth structure GV Black’s Principles of Access Preparation: 1. Outline form 2. Remove carious tooth structure and defective restorations 3. Convenience form 4. Toilet of the cavity Outline Form  Must be correctly shaped and positioned  Depends on the anatomy of the tooth  3 factors of the internal anatomy of the tooth that must be considered for optimal outline form 1. Size and shape of the pulp chamber 2. Number of canals 3. Direction and curvature of the individual root canals Remove Carious Tooth Structure and Defective Restorations Do this before proceeding to RC prep  Mechanically reduces amount of bacteria  Eliminates discoloured tooth structure  Prevents leakage

Convenience Form Unobstructed and access from the canal orifices to the apical foramen Complete control over the root canal instruments Toilet of the Cavity  Removal of caries, debris and necrotic material before canal preparation is done  Burs  Spoon ex  Irrigation using NaOCl Guidelines Law of Pulp Chamber Anatomy 1. Law of Centrality The floor of the pulp always located in the center of the tooth at the level of the CEJ 2. Law of Concentricity The walls of the pulp chamber are always concentric to the external surface of the tooth at the level of the CEJ 3. Law of CEJ The distance from the external surface of the clinical crown to the walls of the pulp chamber is the same throughout the circumferences of the tooth at the level of the CEJ 6 Laws of Pulp Chamber Anatomy (Krasner/Kransar and Rankow):  Needed when evaluating the floor of the pulp chamber in order to locate the canal orifices 1. First Law of Symmetry o Orifices are equidistant from a line drawn in a MD direction across the center of the pulp chamber floor 2. Second Law of Symmetry o Orifices lie on a line perpendicular to a line drawn in a MD direction across the center of the pulp chamber floor  Maxillary molar (exception to laws 1&2) 3. Law of Color Change o The pupal chamber floor is always darker than the walls 4. First Law of Orifice Location o The orifices are always located at the junction of the walls and floor 5. Second Law of Orifice Location o The orifices are always located at the angles of the floor-wall junction 6. Third Law of Orifice Location o The orifices are always located at the terminus of the roots’ developmental fusion lines

General Guidelines 1. Access cavities o Anterior teeth – lingual surface o Posterior teeth – occlusal surface 2. Visualize the position of the pulp space in the tooth 3. Enter the pulp chamber by breaking through the roof of the chamber (“drop” into the chamber) 4. Unroof the pulp chamber o Remove all overhangings of dentin o Outward motion 5. Removal of coronal pulp to have visibility of pulp chamber 6. Evaluate the floor of the pulp chamber for the location of orifices 7. Flare or diverge all walls o Create and access prep that will allow (#10 or #5) straight line access, can easily get in the working end/apical end 8. Remove defective restorations, caries, necrotic material 9. Remove the unsupported tooth structure 10. Place rubber dam only when difficult canals are located Instruments for Access Prep  Mouth mirror  Cotton pliers  Anesthetic solution  Access burs  Endodontic explorer  Endodontic spoon excavator  Endodontic rulers  Clean stand with sponge  Cotton pellets/cotton rolls/gauze/RD assembly  Irrigating solution (NaOCl)/irrigating syringes  Pathfinders  #10 and #15 files (#6-#8)  Composite/GI  Barbed broach Access Prep for Anterior Teeth Common Access Forms Upper central Upper lateral Upper canine Lower incisor Lower canine Point of Entry Above cingulum Middle of tooth Conserve cingulum because it is the strongest part of an anterior tooth 45deg to the long axis of the tooth Drop into chamber to the long axis of the tooth o Incisal edge is the guide to the long axis of the tooth

1. 2. 3.

Unroof the chamber – downward movement Place the incisal bevel Remove the lingual shelf o Extends approx. 2mm apical from orifice

Access Prep for Premolar Teeth Maxillary Premolar Access  Canals can divide deep in the canal  Keep marginal ridges intact  Maintain integrity of tooth Common Access Forms for Maxillary Molars Point of Entry Middle of central groove Lingual area is the bigger part of the chamber o Should go palatally not mesially o Use bur #4 and #6  Aim to locate the palatal canal first  Remove dentin overhangs  Unroof the buccal area  Remove dentin overhangs to have straight line angle to the apex of root  Keep marginal walls intact The Elusive MB2  2/3 the distance between palatal and MB1  Very narrow and covered by a dentin overhang  High percentage of occurrence Common Access Forms for Mandibular Molars (3, 4 or 5th on mesial side) 3 canals – triangular angle forms 4 canals – rhomboidal  Mandibular molars usually have access forms  Aim for the distal canal – bigger canal  Maintain floor of chamber, do not flatten  Maintain bifurcation of roots Point of Entry Only time we can destroy the buccal cusp Canals can divide deep into the canalb Mandibular Molar Access Aim for the distal canal Common errors in Access Prep: 1. Inadequate coronal openings 2. Overextension of access prep 3. Failure to reach main pulp chamber 4. Debris falling into orifices 5. Perforations 6. Misinterpretation of angulation 7. Doing access on the wrong tooth Results of Inadequate Access 1. Bur/file breakage 2. Crown discoloration 3. Root perforation 4. Canal ledging 5. Apical transportation