# Endodontics

* Click to return to School of Dentistry
This is a learning resource about Endodontics which will focus on practical aspects. The project is a work in progress and any contributions or feedback is welcome. For encyclopedic coverage of the topic, see the Wikipedia articles:
* Endodontics
* Endodontic therapy

## Treatment planning

It is sometimes said "Good surgeons know how to cut, better surgeons know when to cut, and the best Surgeons know when not to cut." Really, this adage can be applied to any irreversible treatment in medicine. Modern endodontic techniques mean that virtually any tooth can be root filled, but not everything that can be root filled should be root filled. Endodontic treatment takes time and effort for both operator and patient and should never be carried out in the absence of an evidence-based, overall restorative plan for the whole mouth.
Indications for RCT:
* Irreversibly damaged or necrotic pulp +/- clinical and/or radiologic findings of apical periodontitis
* Elective devitalization, e.g. prior to construction of a post crown, overdenture, doubtful pulp health prior to restorative procedures, likelihood of exposure when restoring a misaligned tooth, and prior to root resection or hemisection
Contra-indications for RCT:
* Unrestorable and/or nonfunctioning teeth
* Teeth with compromised periodontal status
* Teeth with otherwise poor prognosis, uncooperative patients of persons in whom dental treatment cannot be carried out
* Teeth of patients with poor oral condition that cannot be improved withing a reasonable time period
Frequently clinicians and patients are faced with the choice of either root canal treatment or dental extraction. This is a simplified version of an evidence-based decision making protocol to help with this decision (National Health Service, UK):
| | RCT possible | Extraction |
| Medical history | Fit and well | Conscious dental treatment contra-indicated/ potential foci infection undesirable |
| Attendance pattern | Regular | Irregular |
| Patient reliability | Good | Poor/unknown |
| Patient motivation | Good | Poor |
| Oral hygiene | Excellent or good | Poor |
| Reason for RCT | Trauma/acute minimal caries | Gross caries, chronic pathology, crown fracture |
| General periodontal condition | Excellent or good | Poor |
| Number of missing teeth | None, or only a few | >5 |
| Prosthesis | No | Yes |
| Tooth | functioning | Not in function |
| Existing coronal restoration | Plastic, no cusp involvement | Post crown, bridge abutment |
| Pulp | Irreversible pulpitis, but not yet necrosis | Dentoalveolar abscess, discharging sinus |
| Proposed coronal restoration | Plastic, or crown without post | Post crown |
| Full coverage crown accepted? | Yes | No |
| Radiographic pathology | Early/none | Large lesion with periodontal involvement |
| Existing RCT | No | Yes |
| Existing RCT status | Successful | Unsuccessful |
| Canal shape | Favorable | Unfavorable |
| Canal patency on radiograph | Clear | sclerosed |
| Root | Straight | Curved |
| Bone support | >80% | <50% |
| 5 year survival chance | Good | Poor |

## Access cavity

| Maxillary teeth | Mean root length (mm) | Number of roots | Number of canals (%ge cases) | Notes |
| Central incisor | 23 | 1 | 1 | Triangular access cavity. Start at cingulum, widen towards incisal edge. In the crown, pulp chamber is wider mesiodistally and flattened buccopalatally. At apex root canal is round. |
| Lateral incisor | 22 | 1 | 1 | Apical 3-4 mm of root has palatal curve |
| Canine | 26 | 1 | 1 | Longest tooth. Access cavity is rounder than upper 1 and 2 since only 1 pulp horn. |
| First premolar | 21 | 2 | 1 (5%), 2 (90% B, P), 3 (5% MB, DB, P) | Access cavity starts in center of occlusal groove, then widen buccopalatally to locate canal orifices under P and B cusp tips |
| Second premolar | 21 | 1 | 1 (75%), 2 (75% B, P) | Orifice centrally located, if not widen buccopalatally to look for 2 orifi under cusp tips. Separate canals usually reunite apically. |
| First molar | 22 | 3 | P longer than MB and DB, 3 (40% MB, DB, P), 4 (60% MB1, MB2, DB, P) | Rhomboid access cavity, with distal edge on mesial aspect of transverse ridge. Palatal orofice largest and easiest to locate. DB and P orifi rounder, MB orofice ovoid since ribbon shape of MB root. MB2 between MB1 and P. Can use ultrasonic tip to locate MB2. |
| Second molar | 20 | 3 | P longer than MB and DB 3 (60% MB, DB, P), 4 (40% MB1, MB2, DB, P) | Less chance of MB2, more chance of fusion of canals in 7 and 8's (1 Buccal 1 Palatal) |
| Mandibular teeth | Mean root length (mm) | Number of roots | Number of canals | Notes |
| Central incisor | 21 | 1 | 1 (60%), 2 (40% B, L) | Start cavity at base of cingulum, extend nearly to incisal edge to confirm presence/absence of 2 canals |
| Lateral incisor | 21 | 1 | 1 (90%), 2 (10% B, L) | Similar to central except may have distal curve |
| Canine | 24 | 1 | 1 (90%), 2 (10% B, L) | Access cavity starts at base of cingulum |
| First premolar | 22 | 1 | 1 (75%), 2 (25% B, L) | Access cavity is oval-shaped, wider buccolingually |
| Second premolar | 22 | 1 | 1 (90%), 2 (10% B, L) | |
| First molar | 21 | 2 | 3 (65% ML, MB, D), 4 (35% ML, MB, DL, DB) | Mesial canal orifices found under respective cusp tips. Larger distal orifice is more centered, if not then increased chance of 2 distal canals. |
| Second molar | 20 | 2 | 2 (10% M, D), 3 (90% MB, ML, D) | Increased chance of fused canals in 7s and 8s. |

## References and further reading

Access cavities table
* Manogue M, Patel S, Walker R, 2013 The Principles of Endodontics 2nd Edition; Oxford; Oxford University Press
* Garg N, Garg A, 2010; Textbook of Endodontics 2nd Edition; Jaypee Brothers Medical Publishers
Resources
* "Endo cheat sheet"