2020-09-24
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ANATOMY OF INDIVIDUAL TEETH
Depending on the form and function our teeth are divided into 4 groups. They are incisors (used for biting), canines (cuspids) that are used for gripping, premolars and molars which are used for chewing. The clinical formula of teeth is the following: 2 incisors, 1 cuspid, 2 premolars and 3 molars. Wisdom teeth, also known as third molars, are the last set of teeth to erupt in your mouth. This generally occurs between the ages 17 and 25, a time of life that has been called the “Age of Wisdom”.
Incisors have one root and flattened chisel-shaped crowns. The upper crowns are much wider than their lower counterparts.
The upper lateral incisor crown is smaller than the upper central; out the lower lateral crown is slightly larger than the lower central. They have large conical crowns and one long root. Canines are relatively long, pointed teeth that are situated between the incisors and the premolars. The upper canine is larger than the lower one and has the longest root of the whole dentition.
The upper first premolar has two roots, one buccal and one palatal. The remaining premolars have one root. Each premolar has two cusps, one buccal and one palatal or lingual.
The cusps of upper premolars are much bigger than lowers and are almost equal in size. The lingual cusp of lower premolars is much smaller than the buccal cusp.
Upper molars have three roots, two buccal and one palatal. The buccal roots are mesial and distal. Lower molars have four cusps, two buccal and two palatal. Their crowns are characterized by an oblique ridge which runs from the mesio-palatal cusp to the disto-buccal cusp. Upper first molars often have an extra cusp on their mesio-palatal surface.
Lower first molars have five cusps, three buccal and two lingual. Lower second molars have four cusps, two buccal and two lingual.
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First molars are the largest teeth of all. Third molars are very variable in size and number of roots and cusps. Usually they are the smallest molars and their roots are frequently fused together.
Deciduous molars are like miniature permanent molars. They have the same number of roots but their crowns are much whiter and more bulbous than permanent ones. To provide space for the developing premolars, the roots of deciduous molars are more divergent than those of permanent molars.
Exercise 5. Answer the questions to the text.
1. What are the teeth divided into according to their form and function?
2. How many roots do incisors have?
3. What tooth has the longest root in the whole dentition?
4. How many roots does the upper 1st premolar have?
5. What teeth have tree roots?
6. How many roots do molars have?
7. How do the roots of deciduous teeth look like?
8. Roots of what teeth are frequently fused together?
9. What teeth are called wisdom teeth?
10. What is the clinical formula of the teeth?
Exercise 6. Say whether the following statements are true or false.
1. Wisdom tooth erupts at about 10 years of age.
2. Teeth, used for biting, are called canines.
3. Incisors have more than 2 roots.
4. Flattened chisel-shaped crowns cover the cuspids.
5. Each premolar has two cusps, one buccal and one palatal or lingual.
6. The teeth of a grown-up are divided into 4 groups according to the form and function.
7. First molars are the largest teeth of all.
8. Teeth, used for gripping, are called molars.
