Anatomy of successful inferior alveolar nerve block

The Mandibular Foramen (MF) is an opening on the internal surface of  ramus of   mandible leading into mandibular canal (MC). The Inferior alveolar vessels &  nerves  enter through the mandibular foramen, pass through  mandibular  canal ,  give  branches to all  mandibular  teeth and exit through mental foramen(MeF) as  mental vessels  and nerves. The position of MF is an important anatomical  landmark for  effective anaesthesia in Dentistry by Inferior Alveolar  Nerve Block (IANB) for many surgical procedures like lower jaw dental extraction, reduction of  mandibular fractures as well as placing mandibular implants . The accomplishment  of successful anaesthesia in  IANB depends on the proximity of the needle tip to the  MF at the time of injection of local anaesthetic agent. Aim of our study is to examine and evaluate the position of MF relative to four (4)  bony landmarks in 100 dry samples of adult dentulous human mandibles. Materials and Methods : Dry human Mandibles were obtained from Department of Anatomy, Medical College, Kolkata (India).Parameters  were measured by  digital  vernier callipers. The data was tabulated and statistically analysed. Results: The mean distance between the Mandibular Foramen (MF) and the  respective landmarks were noted as (17.06±2.567) mm , (9.75±1.68) mm.  (22.71±3.41) mm.and ( 13.58±2.116 ) mm.for the anterior, posterior, inferior and  superior  border                ( mandibular  notch) respectively for the right side. Likewise distances  on the left sides were—(17.17±1.647)mm, (9.80±1.546) mm, (22.635±3.53) mm.  And (13.52±2.026) mm. for the anterior, posterior, inferior and superior  border ( mandibular notch) respectively. Statistically, there was no significant difference in the distance between mandibular foramen and respective four  landmarks of both the sides. Conclusion : Our study revealed almost bilateral symmetry for all the landmarks  taken   under consideration. We conclude that the failures in the anaesthesia of  Inferior alveolar nerve are mainly due to operator’s error and not due to anatomical  variations. Though the knowledge of minor anatomical variations definitely will help the dental surgeons during local anaesthesia involving IANB for Orthodontic procedures.