Frequency and Type of Canal Isthmuses in First Molars Detected by Endoscopic Inspection During Periradicular Surgery

By von Arx T.

Date: 01/2005
Journal: IEJ


  • Purpose: assess the presence and type of canal isthmus in first molars.
  • N= 88 teeth (32 Max/ 56Mand) Exclusion criteria: medical condition contraindicated for oral surgical procedure with/ advanced marginal periodontitis, 2nd permanent molars


  • Surgical procedure: OR, under LA triangular/trapezoidal flap was raised, affected roots resected 3-4 mm.
  • Isthmus evaluation: after methylene blue staining rigid endoscope was placed.
  • Number of canals and type of isthmus present was recorded.
  • Isthmuses classification according to Hsu & Kim1.

Most highlighted Results:

  • Most often treated root is mesial root of mandibular 1st molar.
  • Mandibular molar isthmus present 83% in mesial root, mostly type IV,V and II. Isthmus present 36% in distal root, mostly type V.
  • Maxillary molar isthmus present 76% MB root, mostly type II.
  • Never present in Palatal and disto-buccal roots.
  • None of the isthmuses were obturated by orthograde filling.

Clinical Significance:

The importance of irrigation activation