i need to extract only a single tooth from the given image but i dnt know which algorithm to select. i had gone through thresholding technique but not able to segment the tooth properly.

The paper talks about the extracted tooth and am using a normal xray of a alive patient. so the issue is my only focus is on canine tooth only and i need to segment only that tooth. for segmenting the tooth i tried threshold method but couldnt get a proper output.