Melgaco Equation Analysis

Efficacy of Melgaco Equation in Predicting Permanent Mandibular Canine and Premolars width
INTRODUCTION
Mixed dentition is the period that includes both the primary and permanent dentition, begins at the age of 6 years with eruption of lower 1st permanent molar or lower permanent central incisor and ends with the eruption of 2nd permanent molar. It is necessary to perform mixed dentition analysis because it is used to calculate difference between the space available and space required by the tooth material for the alignment of the teeth, so that we can decide if the treatment plan would involve periodic observation, serial extraction, guidance of eruption, space regaining and space maintenance.
During the transition from mixed to permanent
However, these methods usually over estimate or under estimate the size of canine and premolars which can be a problem during the treatment. While radiographic methods boast precise information compared to regression tables, these techniques require advance equipment and trained technicians, in addition to their cost ineffectiveness. On the other hand regression tables and equations using four permanent incisors and molars have the advantage that: it has less chances of error and deviation from the error is known, it can be done with similar reliability, does not require expert interpretation, less time consuming, do not require sophisticated equipment, can be performed easily on dental cast, and in mouth precisely.
One of the methods of regression equation and prediction is Melgaco equation. Melgaco et al postulated that sum of mesio-distal width of mandibular 1st permanent molar with the mesio-distal width of 4 mandibular permanent incisors is a good predictor for the sum of permanent canines and premolars. They proposed the following regression
A digital Vernier caliper will be used to measure the mesio-distal width of incisors, canine, pre-molars and molar. To determine the consistency of measurements, readings will be obtained twice separately between 20 days interval.
The sum of mesio-distal width of incisors and molars will then be used to predict the width of canine and premolar using Melgaco equation and then compared with the actual sum of mesio-distal width of canine and premolars.
Y= 0.975X (male patient) Y=0.971X (female patient) Y=0.973X (both sexes) Where, Y (dependent variable) is the predicted mesio-distal width of mandibular permanent canine and premolar on both sides. X (independent variable) is the sum of mesio-distal width of 4 mandibular permanent incisors and 2 permanent mandibular molars. 0.975, 0.971 and 0.973 are the constant values for male, female and both sexes respectively. Inclusion Criteria:
• Permanent dentition in both arches.
• No previous orthodontic treatment.
• All teeth capable of being measured from left permanent 1st molar to right permanent 1st