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References

Weine FS. Initiating endodontic treatment, 6th edn. Weine, FS. St Louis: CV Mosby; 2004
Baugh D, Wallace J. Middle mesial canal of the mandibular first molar: a case report and literature review. J Endod. 2004; 30:185-186
Ahmed HA, Abu-bakr NH, Yahia NA, Ibrahim YE. Root and canal morphology of permanent mandibular molars in a Sudanese population. Int Endod J. 2007; 40:766-771

Access cavity walkthrough: lower mandibular first molar

From Volume 42, Issue 10, December 2015 | Pages 983-985

Authors

Preyesh Patel

BDS

King's College London, Guy's and St Thomas' Hospital, Westminster Bridge Road, London SE1 7EH, UK

Articles by Preyesh Patel

Article

Access cavity preparation is crucial in the success of endodontic therapy. A well designed access cavity can help identify all the canals, allow thorough chemo-mechanical debridement and reduce unnecessary tooth tissue removal. The following article will focus on how to maximize efficiency when preparing an access cavity in a lower mandibular molar.

Stages:


Stages Diagram Description
1. Identifying anatomical landmarks In most cases the roof of the pulp chamber is between and below four anatomical landmarks:
  • BL groove
  • Central groove
  • MB cusp
  • Mesial marginal ridge
    		•
    2. Initial access Create an initial access trough into the pulp chamber 1mm distal from the mesial marginal ridge extending 1mm distal to BL groove.
    3. Locate ML and DL canals Using an endodontic explorer such as a DG 16 probe or handfiles, locate the ML and DL canal.If the canals cannot be located, extend the prep slightly until the orifices are found.
    4. Extend preparation Extend the prep into a rectangular shape to enable finding MB canal and a potential second distal canal, present in 30% of mandibular molars.1If the distal canal is located near or along the central groove, it is highly likely that only one distal canal is present.
    5. Modify access cavity Flare mesial wall to allow unimpeded straight line access. The distal wall can be slightly undercut to preserve tooth tissue, whilst still allowing thorough chemo-mechanical debridement.
    6. Locate middle mesial canal Try to locate a middle mesial canal between ML and MB canal. It is reported that it can exist in 1–15% of mandibular first molars.2Create a trough 1mm deep between ML and MB canal to find a potential middle mesial canal.

    Case:

    LR6 RCT – Procedure Summary:

  • Irrigation technique: sodium hypochlorite and EDTA gel.
  • 3 canals identified: ML, MB and DL. Studies show that 4 canals are found in the mandibular first molar in 59% of cases.3
  • Each canal prepared to 20mm using MB cusp as reference.
  • F2 ProTaper file used to finish preparation of each canal to working length.
  • F2 gp point used to obturate each canal.
  • Cavity restored with RMGIC post-obturation.
    • Figure 1. LR6 showing chronic periradicular periodontitis.
    Figure 2. Post-obturation radiograph showing early evidence of resolution.