This study evaluated the effectiveness of diode laser irradiation combined with topical fluoride application for increasing the hardness of demineralized bovine enamel and esthetically improving white-spot lesions (WSLs). In addition, the study evaluated intrapulpal temperature changes during laser irradiation. One hundred twenty bovine incisors with 4 × 4-mm artificial WSLs were randomly assigned to 8 groups (n = 15): untreated control; fluoride only; LF1, LF2, and LF3, fluoride plus 2-W laser for 15, 30, and 60 seconds, respectively; and LF4, LF5, and LF6, fluoride plus 5-W laser for 15, 30, and 60 seconds, respectively. The Vickers hardness number, CIE L*a*b color space values, and visual analog scale ratings for color improvement were recorded at baseline, after demineralization to create the WSLs, and after treatment. The intrapulpal temperature changes were recorded at completion of irradiation for 30 bovine teeth that were assigned to 6 groups (n = 5) to receive doses of irradiation equivalent to the treatment of the corresponding laser groups described previously. Statistical analysis included 1-way analysis of variance and Tukey multiple comparison tests (α = 0.05) The mean Vickers hardness numbers were significantly greater for the laser groups, and mean visual analog scale scores were significantly greater for all the treatment groups (P < 0.05). The fluoride group had a significantly lower mean color change (ΔE*) value (P < 0.05). The mean intrapulpal temperature changes in the 5-W laser groups were significantly greater than those in the 2-W groups (P < 0.05). Diode laser irradiation combined with topical fluoride application significantly increased the hardness and improved the esthetic appearance of WSLs compared to no treatment (control) and fluoride treatment alone. Intrapulpal temperature changes indicated that diode laser irradiation is safer at a 2-W setting than a 5-W setting.