endodontics access

objective of access prparetion

1- locating all the canals 2- un-impeded straight line access to apical third or first canal curvature3- de roofing of pulp chamber and removal of coronal pulp 4- conservation of pulp chamber

• general princiable access outline form is a projection of the internal tooth anatomy into the external tooth surface

caries removal is essential before preparing access

• general considreation

- before beginning the access a preopreative radiograph should be asessed

- in difficuilt cases access can be prepared without rubber dam

- when canal is located a small file (#10) is used to explore canals and determine patency

- access mustn't be under-prepared

- when preparing access throught restortive material most or all of it should be removed

- access can be prepared through existing metal or porcilin crown

aids in canal location include :-

1- knowladge of pulp anatomy 2- preopretive radiograph 3- illumination and fibrooptic handpieces " handpiece with light" 4- magnification ;- loupes amd microscopy

access openning for individual teeth

maxillary incisors ======< trianguliar outline form

- pulp horns should be eliminated to avoid discoloration

- lingual dentin shelf should be removed

maxillary canine ======< ovoid in middle third lingual surface

maxillary premoalr =======< ovoid in the center of the crown "buccolingual"

maxillary moalr ======< outiline is triangular in the mesial part of the tooth base to the facial and apec to lingual ** oblique ridge is left mostly intact

MB , MD AND PALATAL canals , MB2 IS LOCATED LINGUAL AND SLIGHTLY MESIAL TO MB1

mandibular incisors =====< triangular with base incisally and apec cervicaly

if 2 canal are present labial canal is easier to locate

mandibular canine =====< ovoid outline form

mandibular premoalr =====< ovoid access in a buccolingual direction

access is positioned buccal to central groove for first premolar , and centrally for the second premolar

mandibular molar ======< rectangulair or trapezoid access positioned in the mesiobuccal portion of the crown

mb canal is located slightly distal to MB cusp tip , ML in the central groove area

errors in access

1- inadquate preparation

result in decrease access and visability which prevent locating the canal limited ability to remove pulp tissue and obturating material

inadquate straight line access which lead to deflection of the file by coronal interferance and procedurcal errors "leadge formation"

2- excessive removal of tooth strcture

irreversable and can result in weaking of tooth and subsequent

coronal fracture