Permanent Mandibular Incisors Question And Answers

The Permanent Mandibular Incisors

Question 1. Describe in detail about permanent mandibular central incisor.
Answer:

Labial aspect:

• It is regular and evenly tapering.
• It has shape angles.
• The incisal ridge is straight.
• The mesial and distal root outlines are straight.

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• The apical third of the root curves distally.
• The labial face is smooth.
• The incisal third has a flat surface, the middle third is convex.
• The labial surface of the root is regular and convex.

Lingual aspect:

• It is smooth with a slight concavity at the incisal third and convex at the cervical third.
• Marginal ridges are more prominent.
• Concavity is distinct between the marginal ridges.
• The surfaces are regular and symmetrical.

Mesial aspect:

• Labial and lingual outlines are straight.
• The lingual outline has smooth convexity over the cingulum.
• The incisal ridge is rounded or flat.
• The curvature of the cervical line curves initially the root outlines is straight with bluntly rounded or pointed root ends.
• The mesial surface is convex and smooth at the incisal third and becomes broader and flatter at the middle third.

Distal aspect:

• The cervical line curves initially.
• It has marked the development of depression with a deeper, well-defined groove at its center.

Incisal aspect:

• It is bilaterally symmetrical
• The labial surface is wider at the incisal third.

Chronology:

• The first evidence of calcification-3-4 month
• Enamel completed-4-5 years
• Eruption- 6-7 years
• Root completed- 9 years

Measurement:

• Cervicoincisal length of crown-9.5 mm
• Root length- 12.5 mm
• Mesiodistal crown diameter-5 mm
• Mesiodistal crown diameter at cervix -3.5 mm
• Labiolingual crown diameter -6 mm
• Labiolingual crown diameter at cervix -5.3 mm
• Curvature of cervical line – mesial -3 mm
• The curvature of the cervical line – distal -2 mm