Table 3.

Studies applying gray value (GV) CBCT quantitatively

Study	CBCT models	Patients	Application	Resultsa
Aranyarachkul et al34	1	9 human cadavers (63 sites)	Bone density for implant placement	Spearman correlation (R) with Lekholm–Zalb ratings, 0.46–0.60
Barone et al68	1	6 (12 sites)	Bone density after implant placement	Higher relative GVs for immediate implant loading, +5.2% (para-axial), +6.8% (axial)
Brosh et al69	1	8 swine bones	Bone quality at inter-radicular sites for mini-implant placement	Correlation between GV and hardness: 0.70 (maxilla)–0.75 (mandible). Correlation for individual sites only found in mandible.
Fuster-Torres et al70	1	22	Bone density for implant placement	Correlation between GV, resonance frequency and insertion torque, R2 = 0.000–0.548 (average, 0.071)
Kaya et al71	1	16	Bone density in periapical lesions, pre- and post-treatment (2 years)	Significant differences between GV pre- and post-treatment
Lee et al72	1	42 human cadavers	Bone density (osteotomy and implant placement)	Similar Spearman correlation (R) for CBCT and multidetector CT GVs vs subjective drilling resistance (0.59–0.61) and implant insertion resistance torque (0.61–0.63).
Sennerby et al63	1	49	Bone density for implant placement, pre and post (6 month)	Correlation between GV, resonance frequency and insertion torque, R2 = 0.21–0.31
Simon et al73	1	17	Differential diagnosis of periapical lesions	13/17 cases showed correspondence between CBCT GV and biopsy Validity of biopsy questioned for four other cases
Song et al74	1	20	Bone density for implant placement	Correlation coefficient for CBCT GVs and implant stability quotients, 0.2887–0.7525
Tatli et al75	1	23 (77 implants)	Bone density for implant placement	Spearman correlation of CBCT GVs vs implant stability quotients at four time points, R = 0.544–0.874 CBCT GV vs stability loss, R = −0.470

^aRecalculated to R² when explicitly stated that R was used.