Endodontic Access Flashcards
Describe the basic principles of endodontic access
- Sound knowledge of tooth and root anatomy
- Parallel pre-operative radiograph
- Prepare access before placing rubber dam
- Good illumination and magnification
- Locate the major pulp horn
- Copious irrigation and note colour changes
Describe 2 objectives for all access cavity preparations
- Allow unimpeded entry of instruments into root canals (straight line access)
- Allow sealing of cavity between visits
Name 4 important features of access cavities
- Site
- Size
- Shape
- Depth
Describe the average root length and number of canals in maxillary central incisor
23mm with 1 canal
Name 2 features of maxillary central incisors
- Access starting at cingulum and extending towards incisal edge
- Triangular shape to encompass pulp horns
Describe the average root length and number of canals in maxillary lateral incisor
22mm with 1 canal
Describe a key features of maxillary lateral incisor
Apical 3-4mm has palatal curvature
Describe the average root length and number of canals in maxillary canine
26mm with 1 canal
Describe 1 key feature of maxillary canine
Rounder access cavity than incisors (no need to flare access cavity as 1 pulp horn)
Describe the average root length and number of canals in maxillary 1st premolar
21 mm with 1 (5%), 2 (90% - B,P) or 3 (5% - MB,DB,P) canals
Describe 2 key features of maxillary 1st premolar
- Access centre of occlusal central grove
2. Widen access B-P to locate root canal entrance
Describe the average root length and number of canals in maxillary 2nd premolar
21mm with 1 (75%) or 2 (25% - B,P) canals
Describe 1 feature of the maxillary 2nd premolar
If only 1 root canal should be centred and oval in shape (B-P) to encompass pulp horns
Describe the average root length and number of canals in maxillary 1st molar
- 22mm (P longer than MB and DB)
- 3 (40% - MB,DB,P) or 4 (60% - MB1,MB2,DB,P) canals
Describe 3 features of maxillary 1st molars
- Rhomboid access cavity outline
- Distal aspect on mesial aspect of transverse ridge
- MB2 located between MB1 and P
Describe the average root length and number of canals in maxillary 2nd molar
- 20mm (P longer than MB and DB)
- 3 (60% - MB,DB,P) or 4 (40% - MB1,MB2,DB,P) canals
Describe 3 features of maxillary 2nd molar
- Lower incidence of MB2
- DB root canal closer to centre of tooth
- Increased likelihood of fusion of canals (B-P)
Describe the average root length and number of canals in mandibular incisors
21mm with 1 (60%) or 2 (40% - B,L) canals
Describe 2 features of mandibular incisors
- Starts at base of cingulum
2. Should extend to nearly to incisal edge to confirm presence or absence of 2nd canal
Describe the average root length and number of canals in mandibular canines
24mm with 1 (90%) or 2 (10% - B,L) canals
Describe 1 feature of mandibular canines
Starts at the base of the cingulum
Describe the average root length and number of canals in mandibular 1st premolars
22mm with 1 (75%) or 2 (25% - B,L) canals
Describe 2 features of mandibular 1st premolars
- Starts in central occlusal groove
2. Access is oval bucco-lingually in shape
Describe the average root length and number of canals in mandibular 2nd premolars
22mm with 1 (90%) or 2 (10% - B,L) canals
Describe 2 features of mandibular 2nd premolars
- Starts in central occlusal groove
2. Access is oval bucco-lingually in shape
Describe the average root length and number of canals in mandibular 1st molars
21mm with 3 (65% - ML,MB,D) or 4 (35% - ML,MB,DL,DB) canals
Describe 2 features of mandibular 1st molars
- Mesial root canal orifices found below respective cusp tips
- If distal root canal orifice not centred then inc likelihood of 2nd canal
Describe the average root length and number of canals in mandibular 2nd molars
20mm with 3 (90% - MB,ML,D) or 2 (10% - M,D) canals
Describe 1 feature of mandibular 2nd molars
Increased incidence of fused root canals
Describe isolation during endodontic treatment
- Rubber dam is mandatory
- Prevents infection of the root canal
- Protects the patient from irrigants
- Access cavity cut before placing rubber dam
Name 2 ways magnification can be achieved during endodontic treatment
- Loupes
2. Microscopes
Name 2 burs used for accessing canals
- Straight diamond fissure bur gains access through enamel
2. Size 6 round bur to remove dentine and locate relevant canals
What is the apical constriction?
Narrowest part of the root canal system lying around 0.5-1mm short of the apical foramen
Name 5 contributing factors to working length determination
- Previous radiographs
- Average values
- Diagnostic working length radiographs
- Electronic apex locators
- Tactile sensation
Describe how to estimate working length from pre-operative radiographs
- EWL from pre-operative radiographs and average root length
- Use size 10 SS K files until reached EWL
- Take WL radiograph or use electronic apex locator to determine WL
Name 2 problems when taking radiographs during endodontics
- Estimating root canal lengths
- Film placement when instruments, rubber dam and clamps in position
- Identification and separation of canals
What holder is used for taking endodontic x-rays?
Endo ray holder
Name 2 ways to identify and separate canals during endodontic x-rays
- Use different sizes of flies with different numbers of rubber stops in each canal
- Take 2 radiographs using different horizontal x-ray tube-head positions (parallax technique)
Describe electronic apex locators
- Optimum is cemento-dentinal junction with precise position variable
- Modern locators better than tactile or radiographic techniques
- Accuracy 90-100% for 0.5-1mm from apex respectively
- Still need radiographs in combined approach
Name 5 clinical tips when using electronic apex locators
- Remove metallic restorations from access cavity
- File should be large enough to contact walls of root canal system
- Apex / 0 reading is most accurate
- Re-check WL with EAL after coronal 2/3 shaping
- Detects perforations
