EXPANSION
CALCULATOR
about this calculator
PURPOSE
The Expansion Calculator is a tool to mathematically determine the ideal amount of expansion that can safely be performed to coordinate the arches based on each patient’s unique anatomy. It allows us to avoid using cookie cutter expansion prescriptions for all our patients.
HOW TO USE
Measure the following widths and enter into the calculator:
Centre of L and R mandibular troughs
Central grooves of the mandibular molars
Mesiopalatal cusps of the maxillary molars
You must also enter:
The amount of expansion per turn
Your preferred number of turns / day
The desired level overcorrection (in anticipation of relapse)
INTERPRETING YOUR SCORE
The Expansion Calculator calculator will then tell you:
How much expansion is required in the maxilla
The corresponding amount of uprighting required in the mandible
The number of days your patient must turn their RPE
If your patient’s palatal width is adequate and archwire expansion is indicated, you can still use the Expansion Calculator to get a sense of how much archwire expansion is needed to coordinate the arches. Expected space gain is also displayed at the bottom of the calculator for those using the Expansion Calculator in conjunction with the Space Calculators.
REFERENCES
The formulas utilized by the calculators are based on my review of the literature and wisdom passed down by my instructors at the University of Toronto.
If you are curious about where the values come from, check out these references to see the main references I based these calculators on.
EXAMPLE
If you need a more thorough description of how to use the Expansion Calculator, click HERE.
DISCLAIMER
The information provided is intended solely for informational and educational purposes for licensed dental professionals. The orthodontic calculators, while based on evidence from reputable orthodontic literature as well as clinical experience, are tools designed to assist clinical decision-making. They are not intended to make final treatment decisions. Do not take the outputs from these calculators at face value; they are meant to complement, not replace, professional judgment and critical thinking.
These calculators are generalized and not customized for any specific patient case. It remains the responsibility of the treating orthodontist or dentist to thoroughly assess and tailor care to each patient’s individual needs. By using this tool, you acknowledge that the ultimate responsibility for patient care lies with the treating clinician. Ortho Calculator Inc. will not be held liable for any risks, complications, or outcomes associated with acting on the information provided by this website.
The ortho calculators are not intended for use by the general public. If you are not a licensed dental professional, please refrain from using or relying on the calculators or content provided here. By using the Ortho Calculators, you acknowledge and agree to the terms outlined in this disclaimer.