Anatomical features and color characteristics of teeth may affect the recipient signals' nature during dental pulp oximetry, enamel tissue thickness may consider of the most important factors. This clinical study aimd to evaluate the effect of enamel tissue thickness of the upper premolar crown on the accuracy of dental pulp oxygen saturation readings. The results of this study indicate that there is a considerable effect of the dental tissue thickness on the dental pulp oxygenation measurement. So; it is of important to find the suitable adjustments on the PO apparatus, probe, or programs, in order to gain less effect of the anatomical variances between teeth, and thus increasing pulse oximetry measurement accuracy.