Adequate knowledge of the tooth morphology is of paramount importance for clinicians worked in the different branches of dentistry in order to maintain good oral health. Unfortunately, tooth morphology shows a high level of complexity and variability. These anatomical variations have been reported to be related to many factors including age, gender and ethnicity. The permanent first molars are the largest teeth in the maxilla which play an important role in mastication. Because of their early

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... uption, they are more vulnerable to caries and subsequent pulp and periapical pathoses. This chapter will summarize the internal and external morphologic features of these teeth with the reported variations in relation to age, gender and population in order to provide clinicians with the morphological knowledge necessary for performing successful dental treatments.