The shaping and cleaning abilities of self-adjusting files in the preparation of canals with isthmuses after glidepath enlargement with ISO or ProTaper Universal NiTi files

BACKGROUND/PURPOSE: This study compared the shaping and cleaning ability of self-adjusting files (SAF) after glidepath enlargement with ISO NiTi files (Group I) or ProTaper Universal (PTU; Group II) for preparing maxillary premolar canals with isthmuses. MATERIALS AND METHODS: Twenty-eight teeth containing isthmuses were scanned preoperationally after glidepath enlargement and preparation with SAF (n = 14). Changes in canal and isthmus volume, prepared surface, debris volume, and transportation were determined. Data were compared by t test between groups and paired t test within each group. RESULTS: No difference was observed regarding changes in canal volume or prepared surface between the two groups (P > 0.05). Paired t tests showed that the coronal and middle prepared areas of the canal after using SAF in Group I were statistically larger than those using ISO files, whereas the use of an adjuvant preparation with SAF after PTU resulted in a significant increase in the apical prepared area in Group II. ISO and SAF systems deviated less from the center than did PTU and SAF systems at most sections. After the use of SAF, isthmus volumes were significantly increased within each group (P < 0.05). Although less debris resulted from the use of SAF instruments as compared to glidepath instruments, there was no significant difference between both groups (P > 0.05). CONCLUSION: SAF following glidepath enlargement with ISO files could improve preparation of the coronal and middle part of the canals, and adjuvant preparation with SAF after using large-taper instruments increased the apical prepared area.