Evaluation of Surface Crazing and Fracture Resistance of Pediatric BioFlx^® Crowns at Different Autoclave Cycles: An in Vitro Study.

<b>Purpose:</b> This study evaluated the effect of different autoclave sterilization cycles on surface crazing and fracture resistance of NuSmile^® BioFlx^® crowns (BFCs). <b>Methods:</b> Seventy-five crowns were divided into five groups (15 per group) based on the number of autoclave sterilization cycles: zero (control), one, three, five, and seven. Autoclaving was performed at 121 degrees Celsius and 15 psi for 20 minutes. The mesial surface of the crown was evaluated for crazing under 50× magnification using modified Wickersham's criteria. Subsequently, fracture resistance was assessed using a universal testing machine. Data were analyzed using Fisher's exact test and Welch's analysis of variance. <b>Results:</b> Surface crazing increased as the number of sterilization cycles increased. Most unsterilized crowns were free from crazing; however, after one cycle, only 20 percent remained crazing-free, while 80 percent displayed minor crazing. Following three cycles, 73.3 percent of the crowns exhibited crazing covering half the surface, and 26.7 percent extending over half the surface. After five cycles, 80 percent displayed cracks extending beyond half the surface, and 20 percent showed crazing confined to half. By seven cycles, all crowns exhibited significant crazing. Fracture resistance decreased significantly with increasing sterilization cycles, with the highest score observed in the control group and the lowest after seven cycles. <b>Conclusions:</b> Repeated autoclave sterilization significantly affects surface crazing and fracture resistance of BioFlx^® crowns. Clinicians should consider sterilization methods carefully, as repeated autoclaving compromises crown integrity.