Influence of enamel and dentin thickness on SpO2 readings by pulse oximeter in bleached teeth

The objective of this study was to analyze the influence of different enamel and dentin thicknesses on oxygen saturation (SpO₂) readings after dental bleaching. A total of 26 extracted human anterior teeth, sound and without defects, were used. The crown thickness was measured at the middle third using a thickness gauge. Color was evaluated with a spectrophotometer, and SpO₂ readings were obtained through a pulse oximeter coupled to an optical digital simulator, under two perfusion conditions: high (98% SpO₂, 75 bpm) and low (86% SpO₂, 75 bpm). The first reading was performed without the interposition of the dental element, serving as a positive control (L0). After recording SpO₂ and color readings through sound crowns (L1 and C1), the palatal or lingual surfaces were reduced to a thickness of 5 mm (L2), and a new color measurement was performed (C2). The samples were then subjected to dental bleaching, followed by additional color and SpO₂ readings (L3 and C3). Subsequently, the thickness was further reduced to 3 mm, and the measurements were repeated (L4 and C4). Color was evaluated descriptively. Significant differences (p < 0.001) were found between sound teeth (L1) and bleached teeth with 5 mm (L3) and 3 mm (L4) thickness, as well as between unbleached teeth with 5 mm (L2) and the bleached samples (L3 and L4). The findings of this study demonstrated higher SpO₂ readings by the pulse oximeter in bleached teeth. Bleaching had a greater impact on SpO₂ readings than dental thickness, regardless of perfusion condition.