This study aimed to compare the accuracy and reliability of digital versus conventional clinical measurements of the width of keratinized tissue. To this end, the keratinized tissue width was measured at 110 tooth sites in 5 pig jaws. The measurements were made at each site using three-dimensional (3D) scanned images and a periodontal probe. The actual keratinized tissue width was subsequently measured on histologic slides prepared from the same sites, and differences between the histologic slides and the digital and clinical measurements were analyzed to determine their accuracy in two measurement rounds. Furthermore, intrarater and interrater reliabilities were evaluated using the intraclass correlation coefficient (ICC). Here we show that the mean differences (and lower/upper limits of agreement) between the histologic and the digital/clinical measurements were 0.10 mm (-1.34/1.54 mm) and 1.11 mm (-0.69/2.92 mm), respectively, in the first round of measurements (p < 0.01), and 0.04 mm (-1.52/1.59 mm) and 1.05 mm (-0.37/2.48 mm) in the second round of measurements (p < 0.01). Moreover, we found that the intrarater reliability was higher for the digital measurements (ICC = 0.97, confidence interval [CI] = 0.96-0.97) than for the clinical measurements (ICC = 0.87, CI = 0.86-0.89; p < 0.01). Taken together, our results demonstrate that digital measurements of the keratinized tissue width using 3D scanned images can replace conventional clinical measurements using a periodontal probe since they are more accurate and reliable.