Do separated instruments affect pH levels when using calcium hydroxide as intracanal dressing?

BACKGROUND: The aim of this study was to evaluate the effect of intracanal separated instruments with different lenghts on periapical pH levels using calcium hydroxide (CH) as an intracanal medicament. MATERIALS AND METHODS: In total, 60 teeth were used. Following root canal preparation, teeth were divided into four groups (n = 15). In Group 1, 2 mm and in Group 2, 4 mm weakened from the tip of Revo-S NiTi SC2 (Micro-Mega, Besancon, France) instruments were separated in the apical portion of root canals. In Group 3, there was no separated instrument. CH paste was placed in the first three groups. In Group 4, there was no separated instrument or CH paste. Teeth were placed in containers with deionized distilled water. After 1 h and 1, 2, 7, 15, and 30 days, the pH of the solution was measured. RESULTS: At 1 h, Group 3 showed a significantly higher pH than Groups 1 (2 mm) and 2 (4 mm; P < 0.05). At the same time point, Group 1 (2 mm) showed a higher pH than Group 2 (4 mm) without significance. At 1, 2, 7, 15, and 30 days, Group 2 (4 mm) showed a significantly lower pH than Groups 1 (2 mm) and 3 (P < 0.05). At the same time points, Group 1 (2 mm) showed a lower pH than Group 3 without significance. CONCLUSIONS: Separated instrument may affect the rise in periapical pH level when using CH as the intracanal dressing. Therefore, 4 mm of separated instrument in the apical third showed a significant effect.

Comparison of warm vertical compaction and cold lateral condensation of α, ß gutta-percha and resilon on apically extruded debris during retreatment.

BACKGROUND: This study was performed to evaluate the amount of apically extruded debris removed from a root canal filled with cold lateral condensation (CLC), and warm vertical compaction (WVC) techniques, using b or a phase gutta-percha with AH-Plus (Dentsply DeTrey, Konstanz, Germany) or Resilon (Resilon Research LLC, Madison, WI) with RealSeal SE (SybronEndo, Amersfoort, The Netherlands). MATERIALS AND METHODS: About 100 human incisor teeth were prepared with a #25.06 NiTi rotary system and divided into five groups according to the filling material used: Group 1: CLC (gutta-percha, AH-Plus); Group 2: WVC (b phase gutta-percha, AH-Plus); Group 3: WVC (a phase gutta-percha, AH-Plus); Group 4: CLC (Resilon, RealSeal SE); and Group 5: WVC (Resilon, RealSeal SE). Extruded debris during the retreatment procedure was collected in preweighed Eppendorf tubes. The times required for retreatment were recorded. RESULTS: The amount of debris extrusion was significantly greater with WVC than CLC in the gutta-percha and Resilon groups (P < 0.001). Using a phase gutta-percha resulted in significantly more debris extrusion than b phase gutta-percha (P < 0.001). In the WVC groups, Resilon caused significantly more debris extrusion than gutta-percha (P < 0.05). Retreatment was faster for CLC than WVC (P < 0.05). CONCLUSIONS: In the retreatment procedure, the amount of apically extruded debris and retreatment duration were dependent on the type of obturation material and technique used.

Evaluation of apically extruded debris during root canal retreatment with several NiTi systems.

AIM: To compare the amount of debris extruded apically during root canal retreatment using ProTaper, Mtwo and Reciproc instruments with hand H-files. METHODOLOGY: In total, 60 freshly extracted human mandibular incisor teeth were used. All root canals were prepared with a Reciproc R25 file than filled with Gutta-percha and AH Plus sealer using cold lateral condensation before being assigned randomly to four groups (n = 15 each). In group 1, root fillings were removed with the Protaper Universal retreatment system; ProTaper Universal F3 and F4 instruments were used for the final preparation. In group 2, root fillings were removed with the Mtwo retreatment system; Mtwo size 30, .06 taper, size 35, .06 taper and size 40, .06 taper files were used for the final preparation. In group 3, root fillings were removed with Reciproc R25 instruments; Reciproc R40 instruments were used for the final preparation. In group 4, the root fillings were removed with Gates Glidden burs and sizes 35, 30 and 25 H-files; for final preparation, a size 40 H-file was used. Glass vials were used for debris collection. The vials were weighed before and after Gutta-percha removal. Additionally, the times required for the retreatment procedures were recorded. Data were analysed statistically using one-way analysis of variance. RESULTS: The Reciproc system produced significantly smaller amounts of apical extruded debris than the other groups (P < 0.05). There was no significant difference between the Mtwo, H-file and ProTaper groups. The ProTaper and Reciproc groups required significantly less time than the Mtwo and H-file groups (P < 0.001). CONCLUSIONS: Use of the reciprocating single file system resulted in the extrusion of significantly less debris compared with the full-sequence rotary NiTi instruments and hand filing. Use of the ProTaper and Reciproc instruments required less time for retreatment procedures than use of the Mtwo or H-file.

Evaluation of apically extruded debris associated with several Ni-Ti systems.

AIM: To evaluate the apical extrusion of debris associated with several root canal preparation systems in vitro. METHODOLOGY: Forty-five extracted human mandibular premolars with single canals and similar lengths were used. The root canals were instrumented using ProTaper Next (Dentsply Maillefer, Ballaigues, Switzerland), Twisted File (SybronEndo, Orange, CA, USA) or WaveOne (Dentsply Maillefer, Ballaigues, Switzerland). Debris extruded apically during instrumentation was collected into pre-weighed Eppendorf tubes. The Eppendorf tubes were then stored in an incubator at 70 °C for 5 days. The Eppendorf tubes were weighed to obtain the final weight of the Eppendorf tubes plus extruded debris. Three consecutive weights were obtained for each tube. The groups were compared using the Kruskal-Wallis one-way analysis of variance on Ranks and Tukey's test. RESULTS: The ProTaper Next group produced the highest mean extrusion value whilst WaveOne produced less debris compared with all the other instruments (P > 0.05). There was a significant difference between the ProTaper Next and WaveOne group (P < 0.05). CONCLUSIONS: Apically extruded debris was associated with all instrumentation techniques. The WaveOne system extruded less debris compared with the Twisted File and ProTaper Next.

Effect of solvents on the accuracy of the Mini Root ZX apex locator.

AIM: To evaluate ex vivo, the effects of three solvents on the accuracy of a contemporary electronic root canal length measurement device (ERCLMD), the Mini Root ZX. METHODOLOGY: The actual working length (AWL) of 56 extracted maxillary incisor teeth were measured with an ERCLMD. All root canals were prepared with the ProTaper system to AWL. Of them, 20 were filled with gutta-percha and a resin-based sealer (Group A), 20 with gutta-percha and a zinc oxide/eugenol-based sealer (Group B), and 16 roots were used as the control group (Group C). Removal of the root filling and repreparation processes were performed using the ProTaper system. Guttasolv and Resosolv were used as the solvents in Group A and Guttasolv and Endosolv E in Group B. After the removal of the root fillings had been achieved, the same ERCLMD was used to measure the working length (WL). Differences between AWL and WL measurements were analysed by paired t-test, and the accuracy of ERCLMD was assessed using chi-squared tests. RESULTS: There were significant differences between AWL and WL measurements in subgroups A2 (Resosolv group) and B2 (Endosolv E group). In these subgroups, WL was shorter than AWL (P < 0.05). Also, the accuracy of the Resosolv group was significantly lower than the others (P < 0.05) at a ±0.5 mm margin of error. CONCLUSIONS: Removing root fillings may require use of a solvent. In these cases, ERCLMDs may exhibit a lower accuracy, thus operators must exercise additional care when measuring the working length using ERCLMDs.