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Effect of Premolar extraction on the Bolton’s overall ratio in different
malocclusion groups in local Gujarati Population

Dr. Ashish Kumar
Page No. 1-6


Andrew’s six keys to normal occlusion are essential for a balanced and stable occlusion in
orthodontic patients. Bolton further gave the seventh key “Bolton’s ratio” which is as important as
Andrew’s key during orthodontic diagnosis to achieve best possible esthetic and functional outcome
for patients undergoing orthodontic treatment. Extraction of premolars during orthodontic
treatment have known to cause changes in the Bolton’s overall ratios and affect the interarch tooth
size discrepancies in these patients. 106 pretreatment study models with different malocclusions as
per Angle’s classification were subjected to Bolton’s analysis and Bolton’s overall ratios were
calculated for all study subjects and compared with the ratios obtained after hypothetical extraction
of premolars of different combination to determine their effect on overall ratios. In all malocclusion
groups, it was observed that extraction of 55 and 54 affected the Bolton’s overall ratios more
significantly as compared to extraction of 44 and 45.
Key words: Bolton’s Ratio, premolar extraction, Angle’s classification of malocclusion

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