Linderharth Index

Linderharth Index

• The liderharth index is a maxillary expansion index. It suggests how much maxillary expansion is needed to eliminate crowding.
• As per Linderharth, the ratio of combined incisor to transverse arch width from the center of the occlusal surface of teeth in the first premolar area is ideally 0.85, and in the first molar area, it is 0.65.

“Linder Harth Index Predictive Accuracy”

Linderharth Index Method

• The mesiodistal width of maxillary incisors is measured and added.
• In the premolar area, the width of the arch is measured from the deepest point in the transverse fissure of the fist premolar in the same arch to the fist premolar in the opposite arch.
• In the molar area, the width of the arch is measured from the point of intersection of the transverse fissure with the buccal fissure of the first permanent molar on the same side to the first permanent molar on the opposite side.
• In the premolar region, the expected arch width is SI × 100/85

“Linder Harth Index Limitations”

• If the value that is measured is less than the calculated value, it suggests the need for expansion.
• In the polar regions, the expected arch width is SI × 100/65.
• If the value that is measured is less than the calculated value, it suggests the need for expansion.