If the maxillary first molar is found to have four, the fourth canal is likely found.. In the mesio-buccal root If the maxillary first molar is found to have four, the fourth canal is likely found: a. In the disto-buccal root. b. In the mesio-buccal root. *** c. In the palatal root. d. None of the above. Share This: Facebook Twitter Google+ Stumble Digg Email ThisBlogThis!Share to XShare to Facebook