Crack Repair in Hydroxyapatite Bioceramics Using an Ultraviolet Ultrafast Laser

ABSTRACT Cracks in the tooth enamel may lead to cracked tooth syndrome, posing a potential threat to overall health. Hydroxyapatite (HAP) is the principal component of tooth enamel. In this paper, the repair of initial crack on the surface of HAP are demonstrated using an ultraviolet picosecond laser. The influences of laser processing parameters on the widths of dendritic cracks after laser melting repair were investigated. Although the laser repair results in the formation of dendritic cracks, the width of dendritic crack is submicron‐scale. The localized temperature rise of HAP during laser repair is 3.5 ± 0.2 °C, which could effectively avoid the dental pulp damage in the clinical application. Moreover, the average hardness of HAP specimens significantly increases after laser repair (from 188.3 ± 37.2 HV to 501.9 ± 86.1 HV). With an optimized set of laser parameters, the proposed method has potential for rapid repair of early cracked teeth.