Table.

Enamel Volume and Mineral Content by Ashing Combined with BSE Compared with µCT Alone

Stage	ESS	M/LS	EM	MM	MM	LM	LM	LM
Enamel Segment (1 mm)	1	2	3	4	5	6	7	8
“Classic” % Mineral1	30	50	75	90	95	95	95	95
BSE n = 3
Estimated Volume (mm3)
Mean	0.01165	0.04634	0.07120	0.07324	0.07211	0.06945	0.06860	0.06741
SD	0.00492	0.00204	0.00094	0.00012	0.00024	0.00027	0.00040	0.00176
Expected Mineral Weight2 (µg)	11.0	73.1	168.5	208.0	216.2	208.2	205.7	202.1
Ashing n = 12
Measured Mineral Weight (µg)
Mean	2.27192	16.76667	42.54167	81.16333	133.54167	CND	CND	CND
SD	1.45047	5.82757	12.99094	23.63171	20.95564
BSE-Ashing
Estimated Non-mineral Components
Volume3 (mm3)	0.00924	0.03571	0.05323	0.04467	0.02757	–	–	–
% Volume4	79.31	77.06	74.76	60.99	38.23	–	–	–
% Mineral5	20.69	22.94	25.24	39.01	61.77
Estimated Mineral Weight6 (µg)	1.54	7.69	14.32	35.18	86.83	–	–	–
MicroCT n = 8
Computed Volume3 (mm3)
Mean	–	–	0.06251	0.06817	0.06509	0.06369	0.06275	0.06477
SD			0.01068	0.00489	0.00462	0.00427	0.00496	0.00574
Computed Mineral Weight (µg)
Observed	–	–	44.48067	85.91591	133.93322	168.64554	182.44505	192.12524
SD			11.19431	23.91890	17.26646	9.734022	12.12689	16.35890
Non-mineral Components
Volume (mm3)	–	–	0.04601	0.04001	0.02477	0.01210	0.00709	0.00320
% Volume4			73.60	58.69	38.05	19.00	11.30	4.94
Mineral
% Mineral5	–	–	26.40	41.31	61.95	81.00	88.70	95.06

“Classic” % mineral was derived from historical evidence. The expected mineral weight (µg) was derived from the volume and the estimated % mineral. ESS, early secretory stage; MS, mid-secretory stage; LS, late secretory stage; EM, early maturation stage; MM, mid-maturation stage; LM, late maturation stage; and CND, could not dissect, enamel too hard.

Calculations

¹“Classic”% mineral was derived from previously published ashing data.

²Expected mineral weight (µg) was derived from the measured volumes and the estimated % mineral.

³Estimated non-mineral components represents organic material and water. It reflects the ratio of observed to expected mineral weight in consideration of the average volume for an enamel slice, according to:

$$\text{Volume non-minerals}=\text{estimated volume}-(\frac{\text{measured mineral weight}}{\text{expected mineral weight}}\times \text{estimated volume})$$

⁴Percentage volume of non-minerals was calculated as:

$$\%\text{Volume non-minerals}=(\frac{\text{volume non-minerals}}{\text{computed volume}}\times 100)$$

⁵% Mineral was estimated as:

$$\%\text{Mineral}=100-\%\text{Volume non-minerals}$$

For microCT, the measured parameters were volume and mineral density, from which expected mineral weights could be computed as:

$$\text{Weight}=\text{Density}\times \text{Volume}$$

⁶Estimated mineral weight was derived from:

$$\text{Estimated mineral weight}=(\frac{\text{measured mineral weight}}{\text{expected mineral weight}}\times \mathrm{measured\; volume})\times 3156\times \%\text{Mineral}÷100$$