Table 3. The Frequencies of Various Occlusion/Malocclusion Categories in US Population Under Different Levels of TPI Scales.

TPI scale	Category	Frequency (%)
0	Normal occlusion	24.4
1 - 3	Minor manifestations and treatment need is slight	39.0
4 - 6	Definite malocclusion but treatment elective	8.7
7 - 9	Severe handicap, treatment highly desirable	22.4
10	Very severe handicap with treatment mandatory	5.5