This study aimed to evaluate the effect of air‐abrasion/sintering order and autoclave aging on the surface roughness (Ra), phase transformation, and biaxial flexural strength (BFS) of monolithic zirconia. A total of 104 monolithic zirconia specimens (Katana ML) were divided into eight groups according to airborne‐particle abrasion protocols and hydrothermal aging: control (non‐aged: C‐, aged: C+), air‐abrasion before sintering (BS‐, BS+), air‐abrasion after sintering (AS‐, AS+), and air‐abrasion before and after sintering (BAS‐, BAS+). A steam autoclave was used for accelerated aging, and Ra values were measured with a surface profilometer. All specimens were analyzed by X‐ray diffraction to determine any phase transformation on the zirconia surface. BFS was measured by using the piston‐on‐three‐balls method. Scanning electron microscopy and atomic force microscopy were performed on one specimen per group. BS and BAS groups showed higher Ra values compared with groups C and AS. The aging process significantly increased the monoclinic phase content of all specimens. Lower monoclinic levels were found in AS+ and BAS+ compared with other aged groups. The AS groups exhibited higher flexural strength values relative to control groups, whereas BS groups exhibited significantly lower flexural strength values (p < .05). There was no reduction in flexural strength by using the BAS protocol. Air‐abrasion of zirconia at the pre‐sintered stage only is not recommended in clinical use because of the remarkable decrease in flexural strength.

中文翻译：

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烧结前和/或烧结后阶段的空气磨损和水热老化对多层整体氧化锆表面粗糙度、相变和抗弯强度的影响

本研究旨在评估空气磨损/烧结顺序和高压釜时效对整体氧化锆表面粗糙度 (Ra)、相变和双轴弯曲强度 (BFS) 的影响。总共 104 个整体式氧化锆试样 (Katana ML) 根据空气颗粒磨损协议和水热老化分为 8 组：对照（未老化：C-，老化：C+），烧结前空气磨损（BS-， BS+）、烧结后的空气磨损（AS-、AS+）和烧结前后的空气磨损（BAS-、BAS+）。使用蒸汽高压釜加速老化，用表面轮廓仪测量 Ra 值。通过 X 射线衍射分析所有样品以确定氧化锆表面上的任何相变。BFS 采用活塞-三球法测量。对每组一个样本进行扫描电子显微镜和原子力显微镜检查。与 C 组和 AS 组相比，BS 和 BAS 组显示出更高的 Ra 值。老化过程显着增加了所有试样的单斜相含量。与其他老年组相比，AS+ 和 BAS+ 的单斜细胞水平较低。相对于对照组，AS 组表现出更高的抗弯强度值，而 BS 组表现出显着较低的抗弯强度值（p < .05 )。使用 BAS 协议没有降低抗弯强度。由于抗弯强度显着降低，临床上不建议仅在预烧结阶段对氧化锆进行空气磨损。