Comparative dental development and microstructure of ... - UCL

DENTAL DEVELOPMENT IN PROCONSUL
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Figure 11. ‘‘S-shaped’’ striae in the cervical enamel of the P. nyanzae M 2 (left) and the P. heseloni M 1
(right).
(Individual IV) they measured 25 μm apart
maximally. In the high cusped M 1 germ
(Individual IV) 16·7 μm apart maximally,
and in other lower crowned premolars and
molars (Individual III) they measured on
average 12·5 μm apart.
Given that there is a five day periodicity
between enamel striae in this individual, this
implies daily rates of dentine formation were
close to 5 μm per day in the I 1 , 3·3 μm per
day in the high cusped M 1 and 2·5 μm per
day in the other posterior teeth. Both in
these teeth and others, daily lines with this
expected periodicity in this position were
measured (Table 4). This enabled mean
daily rates of dentine formation in the cusps
of several teeth to be estimated specifically
for each tooth.
Two deciduous teeth, the dm 1 and the
dm 2 (Individual IV) had measurable daily
lines in the coronal dentine of around
3·5 μm. Measurements made through the
whole thickness of the cuspal dentine in two
P. heseloni teeth (M 2 and M 3 ), demonstrated
that there was a constant rate of dentine
formation in the axis of cusps, as has been
demonstrated in apes and humans (Dean &
Scandrett, 1995). The mean value (n=23)
for spacings of daily lines made on the
photomontage of the M 2 was 2·4 μm
(S.D.=0·21, range=1·95–2·66). For the M 3
(n=14) the mean value was 2·09 μm