CD31 expression in human primary teeth treated with photobiomodulation therapy

This study aimed to evaluate the effects of photobiomodulation (PBM) on CD31 expression in pulp tissue repair of human primary teeth.

Fifteen mandibular primary molars were divided into the following groups: GI—calcium hydroxide (CH), GII—PBM + CH, and GIII—PBM + zinc oxide/eugenol (ZOE). In the GII and GII groups, an indium–gallium–aluminum phosphide (InGaAlP) diode laser was used for the irradiation through 320-μm diameter optical fiber in contact with pulp tissue. The red laser diode parameters were set at 660-nm wavelength, 10-mW power output, 2.5-J/cm² energy density, 50–60-Hz frequency, output beam area of 0.04 cm², and irradiation time of 10 s in continuous mode. After pulpotomy treatment, clinical and radiographic follow-ups were accomplished until the teeth achieved regular exfoliation period. Teeth were extracted for histological analysis and immunolocalization of CD31. Histopathological statistical analyses were performed by Kruskal-Wallis followed by Dunn test to determine statistically significant differences (p < 0.05).

Although GII showed no inflammation or discreet inflammatory cells, the comparison among the groups using a score system revealed no statistically significant differences regarding inflammation and the amount of blood vessels. The immunohistochemistry analysis revealed positive CD31 expression in the blood vessels of all the studied groups. Immunostaining was observed in large blood vessels associated with inflammatory cells on GI and GIII, whereas GII showed discreet immunostaining predominantly in small blood vessels scattered throughout the pulp tissue with none or rare inflammatory cells.

The CD31 expression was greater in the group PBM when associated with calcium hydroxide. Photobiomodulation therapy followed by calcium hydroxide helped in repairing and seemed to regulate angiogenesis and leukocyte migration processes in the remaining pulp tissue after primary teeth pulpotomy.