CBCT data relevant in treatment planning for immediate mandibular molar implant placement

Immediate molar implants (IMIs) have been shown to provide an effective treatment, but their placement comes with potential anatomically related risks.

CBCTs of>400 dental sites were analyzed for key anatomical features at mandibular molar sites that can impact the placement of IMIs. Features measured included distances from each molar furcation to points risking lingual plate perforation or inferior alveolar nerve (IAC) damage, distances from molar root apices to IAC, mesiodistal and buccolingual widths of molar inter-septal bone (ISB), and thicknesses of buccal and lingual cortical plates at first and second mandibular molar sites.

Distances from molar furcations to contact with lingual cortical plates and to IAC decreased significantly from mesial to distal, as did distances from root apices to the mandibular canal. Both buccolingual and mesiodistal ISB widths and thicknesses of buccal and lingual cortical plates increased mesiodistally. Buccolingual ISB widths were largest coronally for both molar sites and decreased apically. The reverse was found with mesiodistal septal ISB widths, which increased coronoapically.

Risks of lingual perforations or IAC damage were significantly greater at second molars vs. first molars. The ability to place IMIs in ISB at first molars was estimated to be>twice as often as at second molars. Maximal implant lengths for IMIs placed in the furcal bone should not exceed 10 mm.