Ramanujan's equation for calculation of Maxillary Arch perimeter

The Intermolar molar width(IMW), Inter Canine Width(ICW) , and Inter Molar width perpendicular were also measured. All these measurements can have an effect on the maxillary arch perimeter. The relationship between CP, MP and other parameters was assessed in three different classes of malocclusion.

These models class I, Class II, Class III were selected based on certain cephalometric criteria. The distobuccal cusp of the second molar was marked. The midpoint between the central incisors is also marked.

The horizontal distance between the left and right second molars at the cuspal points provides the IMW. The perpendicular distance from the midpoint of IMW line to the central point of incisors ( IMW Per) provides us the arch length. It also indicates the arch length that can be increased or decreased with the proclination or retroclination of the Central Incisors.

The arch perimeter can be increased for gaining space during the correction of malocclusion by non-extraction means. The perimeter can be either increased by Increase in IMW or IMW per. The amount of space that can be gained is accurately derived by this mathematical expression.