In orthodontics, the most controversial role of the third molar is whether it contributes to the development of malocclusion or relapse to irregular alignment, particularly in anterior dental arch segment. The belief that erupting tooth transmits anterior component force down the dental arch that results in a breakdown in the continuity of contact particularly in incisors and canines is intuitively appealing and pervades both the dental specialists and the public. However, there are no conclusive evidence to indict the third molars as being the major etiologic factor in the post treatment changes in incisor.This book elucidates different opinions of orthodontists whether or not there is some type of relationship between the presence of erupting/ impacted third molars and incisor crowding, from the perspective of helping the clinician with decision making on conclusion of his or her orthodontic cases.