. 2020 Feb 17;15:38. doi: 10.1186/s13014-020-01486-7

Table 1.

Mean and Standard Deviation of recorded acoustic impedance values for each region and irradiation dose obtained by 320 MHz Scanning Acoustic Microscopy (SAM). The statistically significant irradiated groups were marked with the asterisk ^a

Dose	Acoustic Impedance Z (MRayl)
	Enamel		P value	Dentin		P value
	Pre-irradiation	Post-irradiation	P value	Pre-irradiation	Post-irradiation	P value
2 Gy (n = 9)	12.94 ± 0.67	12.65 ± 0.43	>.9999	7.94 ± 0.69	7.42 ± 0.35	> 0.9999
8 Gy (n = 9)		11.88 ± 0.35	.5594		7.39 ± 0.27	> 0.9999
20 Gy (n = 9)		11.37 ± 0.63	.0632		6.52 ± 0.43 ^a	0.0296
30 Gy (n = 9)		7.24 ± 0.18 ^a	.0002		5.71 ± 0.66 ^a	0.0006
60 Gy (n = 9)		6.49 ± 0.28 ^a	<.0001		4.82 ± 0.53 ^a	< 0.0001

^aSignificant difference