Number of lobes in a tooth

 # The minimum number of lobes from which any tooth may develop is:

A. Two

B. Three

C. Four

D. Five

The correct answer is: C. Four.

Tooth development begins with increased cell activity in growth centers in the tooth germ. A growth center (lobe) is an area of the tooth germ where the cells are particularly active. These lobes are primary centers of calcification and are primary sections of formation in the development of the crown of a tooth. They are represented by a cusp on posterior teeth and mamelons and cingula on anterior teeth. They are always separated by developmental grooves, which are very prominent in the posterior teeth and form specific patterns. With anterior teeth, their presence is much less noticeable and these lobes are separated by what are known as developmental depressions.

Summary of number of lobes:

•All anterior teeth: three labial and one lingual (cingulum)

• Premolars: three buccal and one lingual.

Exception: The mandibular second premolar has three buccal and two lingual lobes.

• First molars (maxillary and mandibular): five lobes, represented by five cusps - one lobe for each cusp

•Second molars (maxillary and mandibular): four lobes, one for each cusp

• Third molars: at least four lobes. one for each cusp ***variations arc seen