Question

A baby boy aged two years is admitted to playschool and passes through a dental check-up. The dentist observed that the boy had twenty teeth. Which teeth were absent?
A. Molars
B. Incisors
C. Canines
D. Premolars

Answer 1

Hint: The human teeth function to mechanically break down items of food by cutting and crushing them in preparation for swallowing and digesting. Humans have four types of teeth: incisors, canines, premolars and molars and each has a specific function. The incisors cut the food, the canines tear the food and the molars and premolars crush the food. The roots of teeth are embedded in the maxilla (upper jaw) or the mandible (lower jaw) and are covered by gums.

Complete step by step answer: Humans, like other mammals, are diphyodont, meaning that they develop two sets of teeth. The first set normally starts to appear at about six months of age, although some babies are born with one or more visible teeth, known as natal teeth.
Among deciduous (primary) teeth, ten are found in the maxilla (upper jaw) and ten in the mandible (lower jaw), for a total of 20. In the primary set of teeth, there are two types of incisors; central and laterals, and two types of molars; first and second. Among the permanent teeth, 16 are found in the maxilla and 16 in the mandible, for a total of 32. The maxillary teeth are the maxillary central incisors, maxillary lateral incisors, maxillary canines, maxillary first premolars, maxillary second premolars, maxillary first molars, maxillary second molars, and maxillary third molars. The mandibular teeth are the mandibular central incisors, mandibular lateral incisors, mandibular canines, mandibular first premolars, mandibular second premolars, mandibular first molars, mandibular second molars, and mandibular third molars. Premolars are four in number and are absent in infants which are replaced by the molars in the later stages.
Hence, the correct answer is option is D.

Note: Tooth development is a complex process by which teeth form from embryonic cells, grow and erupt into the mouth. For human teeth to have a healthy oral environment, enamel, dentin, cementum and the periodontium must all develop during appropriate stages of fetal development. Primary teeth start to form in the development of the embryo between the sixth and eighth weeks, and permanent teeth begin to form in the twentieth week.