Diffusion patterns of anesthetic solution in the infiltration anesthesia depending on injection sites in the mandible of rats

PurposeThis study was conducted for the morphological and quantitative evaluation of the diffusible patterns of local anesthetic depending on the site of injection in infiltration anesthesia.ExperimentsThe mandibular first molars of rats were anesthetized by the local infiltration of 30 μl of 2% lidocaine containing trypan blue at a distance of 2 mm from the gingival margin on either the lingual or buccal side over the distal root apex of the first molar. Frozen sections were prepared to measure the volume of the infiltrated anesthetic using volume-calculating software.ResultsOn the lingual side, the local anesthetic infiltrated into the mouth floor and spread backward in a sagittal direction at an infiltration volume of 8.36 ± 7.34 mm3. On the buccal side, the anesthetic solution was restricted to the injected area and the infiltration volume was 2.22 ± 1.62 mm3.Conclusion The present results indicate that the infiltration volume of local anesthetics is very different between the lingual and buccal sides.