Access for Anterior and Single Roots

Question 1

Working Length

Answer 1

From incisal edge to minor apical diameter (apical constriction)

Working length is 0.5mm LESS than the radiographic length

WL + 1mm establishes patency

Question 2

Objectives of Access Preparations

Answer 2

1. Straight line access to canal orifice or first point of curvature
2. Conservation of tooth structure
3. Complete unroofing of the pulp chamber

Question 3

Straight Line Access

Answer 3

Coronal access achieves straight line to the canal orifices at the level of the CEJ

Radicular access takes your coronal access beyond the level of the CEJ to the apical 1/3 or the first point of curvature of the canal

Question 4

T/F: Old restorations should be removed for access preparation even if decay is not suspected

Answer 4

TRUE

This will let you examine the tooth for cracks or fractures that may not otherwise be evident

Question 5

Determine if the tooth is restorable before doing RCT

Answer 5

Yes, if you do the root canal therapy and then figure out that the tooth is not restorable, the patient is going to lose their confidence in your ability.

Question 6

Coronal Endodontic Access

Answer 6

Progressive development of a class I cavity prep on the occlusal or lingual surface penetrating into and eventually unroofing the pulp chamber

Shapes are tooth specific and shaped to match the external shape of the tooth at the CEJ level

Series of 2mm depth cuts that funnel inward

Question 7

Outline Forms for anterior and single rooted posterior teeth

Answer 7

TRIANGULAR:
- maxillary central and lateral

OVAL:
- maxillary canine, mandibular premolars

LONG OVAL with near inclusion of incisal edge:
- mandibular canine, mandibular centrals and laterals

Question 8

Level of ______ should never be exceeded during coronal access preparations

Answer 8

CEJ

DO NOT cross the level of the CEJ on coronal access preps

Question 9

Coronal Access Burs

Answer 9

1157 or # 2 friction grip
- used for all initial outline forms, chamber penetration

2, # 4 round latch
- used to remove chamber roof once chamber is penetrated

Friction grip course flame diamond
- final chamber refinement and smoothing of walls

Question 10

5 Explorer

Answer 10

used to check if roof of pulp chamber still remains

Question 11

DG-16 Explorer

Answer 11

Used to search for canal orifice

Question 12

Maxillary Central and Lateral Access

Answer 12

TRIANGLE outline

Triangle base is towards incisal edge. Base may approach within 3-4mm of incisal edge

Width of base determined by distance between mesial and distal pulp horns

Entire orifice should be seen through the access opening

Teeth may have a lingual shoulder that must be removed in order to mechanically instrument the lingual surface of the canal

Question 13

Maxillary Canine Access

Answer 13

OVAL or slot-shaped

Incisal extent can approach within 2-3mm of incisal edge

Mesial and distal extension determined by medial and distal pulp chamber walls

This tooth can also have a lingual shoulder

Pulp chamber is very narrow M-D and wider Faciolingually

Question 14

Mandibular Canine Access

Answer 14

OVAL or slot-shaped

incisal extent can approach cusp tip, especially if the cusp tip is worn down

Lingual extent can approach the cingulum in order to look for a second canal

Mandibular canine can have more than one root or canal

MD extent corresponds to the MD walls of the pulp chamber

Question 15

Mandibular Incisor Access

Answer 15

OVAL

Buccal extent within 2-3mm of incisal edge in intact teeth

Teeth are narrow in MD direction so access is difficult– make sure to stay in long axis

Lingual shoulder may hide lingual canal– access should extend to the lingual and remove the shoulder to search for the lingual canal.

LINGUAL CANAL IS MOST COMMONLY MISSED CANAL ON MANDIBULAR INCISORS

Question 16

Mandibular 1st Premolar Access

Answer 16

1st premolars:
- one root 95%
- one canal 75%

Access will put you very close to buccal cusp tip due to lingual inclination of crown

Narrow MD direction target

1st 2mm bur penetration is PARALLEL to buccal surface
- reorient bur into long axis for 2nd 2mm depth cut

Question 17

Mandibular 2nd Premolar Access

Answer 17

OVAL

crown has less lingual inclination so less extension to buccal cusp is required (compared to mand 1st premolar)

Lingual cusp more pronounces so lingual extension is further up the inclination of the lingual cusp

Mand 2nd premolar can have TWO LINGUAL CUSPS
- access is centered on a line connecting the buccal cups and the lingual groove between the 2 lingual cusps

MD extent determined by mesial and distal extent of the pulp chamber

1st 2mm depth cup parallel to facial surface

2nd 2mm depth cut in long axis