276 Forensic dentistry
when the French Canadian “norms” deviate from the target samples they are
applied to. The solution is to produce group-appropriate norms that accurately
reflect the target group’s tempo of growth.
Demirjian reflected that the statistical information among the seven tooth
types was largely redundant since the teeth were developing synchronously.^88
Table 13.6 Age at Attainment (Years) of Stages of
Crown-Root Formation of Permanent Incisorsa
UI1 UI2 LI1 LI2Grade x SD x SD x SD x SD
Girls
Ci • • • • • • • •
Cco • • • • • • • •
Coc • • • • • • • •
Cr 1/2 • • • • • • • •
Cr 2/3 • • 4.6 0.51 • • • •
Cr 3/4 • • • • • • • •
Cr c 4.9 0.54 5.7 0.62 • • • •
R 1/4 6.0 0.66 6.6 0.71 4.5 0.51 4.7 0.53
R 1/3 • • • • • • 5.2 0.57
R 1/2 6.6 0.71 7.2 0.76 5.1 0.57 5.9 0.65
R 2/3 7.1 0.76 7.7 0.82 5.6 0.62 6.3 0.68
R 3/4 7.6 0.81 8.3 0.87 6.1 0.66 6.7 0.72
R c 8.2 0.86 9.1 0.95 6.6 0.72 7.6 0.80
A 1/2 8.9 0.93 9.6 0.99 7.4 0.79 8.1 0.86
A c • • • • 7.7 0.82 8.5 0.89
Boys
C i • • • • • • • •
C co • • • • • • • •
C oc • • • • • • • •
Cr 1/2 • • • • • • • •
Cr 3/4 • • • • • • • •
Cr c 5.3 0.59 5.9 0.64 • • • •
R 1/4 6.3 0.68 6.9 0.75 • • 5.3 0.60
R 1/3 • • • • • • 5.6 0.62
R 1/2 6.9 0.74 7.6 0.80 5.2 0.59 6.2 0.68
R 2/3 7.6 0.80 8.1 0.86 5.8 0.64 6.8 0.74
R 3/4 8.1 0.85 8.7 0.91 6.4 0.70 7.4 0.78
R c 8.6 0.90 9.6 1.01 7.0 0.75 8.0 0.84
A 1/2 • • • • 7.7 0.81 8.5 0.90
A c • • • • 8.1 0.85 9.3 0.98
a Codes: cusp (C), crown (Cr), root (R), apex (A). Stages: initiation (i),
coalescence (co), cusp outline complete (co), complete (c), cleft (cl).