Fig. 1

Representative images from different cross-section levels in each group, showing how before and after-operative Micro-CT scans were co-registered and overlapped. Grey indicates uninstrumented canal space, while red indicates instrumented canal space. Group 1: Glide path was established by using #10-#15 stainless steel K-files manually; Group 2: #10–#15 Mechanical Glide Path super-files were used with OGP motion (OGP 90°, 300 rpm)