Figure 4

Combined plot of increase in tooth length in both cusps along the EDJ and then up to crown completion in the protocone (arrow at 2.59 years) and continuing beyond this along the CDJ in the damaged palatal root and then onwards to root length complete in the distobuccal root (arrow at 6.75 years). The roots are cross-matched at 4.12 years (Sr line). The plot is extended here to apex closure (AC) at 7.75 years. Each of the component crown and root plots are combined as a single best-fit cumulative growth curve. The plot shows increasing distance along the EDJ/CDJ (µm) against formation time (years) and is expressed here by a 5th order polynomial that allows formation time (Y) to be predicted from a known value of EDJ/CDJ length (X). Although apex closure is extended to 7.75 years here, it may have taken less time. Predictions, using the following formula, of tooth formation time for each successive 1 mm of growth in length along the EDJ/CDJ are also given in Supplementary Table S2: (Eq. 2) Y = .018 + 8.875e−5X + 4.414e−8X2 − 3.009e−12X3 + 4.581e−17X4 + 6.494e−22X5; R2 = .993.