Incisor liability in maxillary arch

 # Incisor liability is about ………..in maxillary arch.

A. 4.6 mm 

B. 5.4 mm 

C. 6.2 mm 

D. 7.6 mm 

The correct answer is D. 7.6 mm.

Incisor liability is about 7.6 mm in maxillary arch and 6 mm in mandibular arch. The incisor liability is compensated by three mechanisms:

a. Increased intercanine width: During the period of permanent incisor eruption, significant amount of increase in intercanine arch width occurs. It is about 3–4 mm.

b. Interdental spacing: Spacing present in primary dentition helps in alignment of incisor. The primate space present in the upper arch mesial to primary canine is also used.

c. Labial eruption of incisor: Primary incisor stand upright. The permanent incisors, which replace them, are labially proclined placing them in a wider arch.

Source: Mc Donald 2nd South Asian Edition