Value of FMA angle ranges between 16-18 degree, then the prognosis is:
FMA angle is the angle formed by mandibular plane and Frankfort horizontal plane. Normal value is 25 Degree. Increase FMA angle or high angle cases indicate vertical growth pattern white decreased FMA or low angle cases indicate horizontal growth pattern.

FMA 16° to 28 ° - prognosis is good. Approximately 60% malocclusions have FMA between 16° to 28°
FMA from 28 - 35 ° - prognosis is fair. Extraction is necessary in majority of cases.
FMA above 35 ° — prognosis is bad. Extractions frequently complicate problems.
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