Space Analysis Calculator

No -- Bolton Overall Ratio is calculated purely from Mandibular 12 Tooth Sum divided by Maxillary 12 Tooth Sum, and Arch Perimeter Available has no role in it. Arch Perimeter Available instead feeds the separate Arch Length Discrepancy calculation, which measures available space against total tooth width and is an independent analysis from Bolton tooth-size ratios.

Maxillary 12 Tooth Sum sits in the denominator of the Bolton Overall Ratio calculation (Mandibular 12 Tooth Sum divided by Maxillary 12 Tooth Sum). A rise in the denominator alone actually moves the ratio less than the same-sized rise in the numerator; it's an equal-sized drop in the denominator that moves the ratio more. Because a two-sided percentage swing combines both directions, Maxillary 12 Tooth Sum ends up with a marginally larger measured spread -- a mechanical property of division, not a clinical statement that the maxillary arch matters more in tooth-size discrepancy analysis.

Overall Significant fires when the measured Bolton Overall Ratio deviates from the 91.3% ideal value by more than two standard deviations (2 x 1.91), a statistical threshold from Bolton's original research indicating the discrepancy is unlikely to be normal variation. It flags a tooth-size mismatch worth clinical attention -- interproximal reduction, restorative buildup, or extraction planning -- but does not by itself dictate which treatment approach to use; that decision requires the clinician's judgment alongside cephalometric and facial evaluation.

No -- they are independent analyses that this calculator reports side by side. Bolton analysis (Overall Ratio and Anterior Ratio) compares mandibular and maxillary tooth widths to each other to detect tooth-size mismatches between arches, while Arch Length Discrepancy compares total tooth width against available arch perimeter within a single arch to detect crowding or spacing, and neither set of inputs affects the other's calculation.