The effect of 1.5 T and 3 T magnetic resonance imaging on microleakage of amalgam restorations.

The aim of this article is to compare the effects of 1.5 T and 3 T MRI on microleakage of amalgam restorations. A total of 90 extracted molar teeth were used in this study. Amalgam was used to restore standard Class V preparations (5 × 3 × 2 mm). Following the restoration, the teeth were divided into three groups according to magnetic resonance imaging (MRI) protocol (Group I: Control, Group II: 1.5 T MRI, and Group III: 3 T MRI). A total of 6,000 thermal cycles at 5°C-55°C were applied on all samples. Microleakage values were measured in millimeters using the ImageJ program. Microleakage values were higher in the gingival region compared to the occlusal region in all groups and the differences were statistically significant (p < .05). Microleakage values were not statistically different among the groups in the occlusal region (p > .05), while there were statistically significant differences among the groups with respect to microleakage values in the gingival region (p < .01). The highest mean microleakage amount in the gingival region was measured in Group III (1.192 ± 0.941 mm). This was followed by Group II (0.519 ± 0.813 mm) and Group I (0.347 ± 0.726 mm), respectively. Within the limitations of this in vitro study, we observed that higher microleakage values in amalgam restored teeth in which were exposed to MRI procedure. We also found that the teeth exposed to the stronger magnetic field showed higher microleakage amount.

Apically extruded debris during root canal preparation using ProTaper Gold, ProTaper Universal, ProTaper Next, and RECIPROC instruments.

PURPOSE: The aim of this study was to determine the amount of apically extruded debris during root canal preparation with ProTaper Gold (PTG) (Dentsply Maillefer, Ballaigues, Switzerland), ProTaper Universal (PTU) (Dentsply Maillefer), ProTaper Next (PTN) (Dentsply Maillefer), and RECIPROC (VDW, Munich, Germany) in curved canals. METHODS: Eighty human mandibular molar teeth were divided into 4 groups according to the system used for root canal preparation: PTG, PTU, PTN, and RECIPROC groups. The mean weight of extruded debris was statistically analyzed using one-way analysis of variance and post-hoc Tukey's test (α = 0.05). RESULTS: The PTU was associated with significantly more extruded debris than the PTG, PTN, and RECIPROC (p<0.05). The PTG was associated with significantly more extruded debris than the PTN and RECIPROC (p<0.05), whereas no significant difference was found between the RECIPROC and PTN (p>0.05). CONCLUSIONS: All systems caused apical debris extrusion during curved canal preparations. However, the PTG, PTN, and RECIPROC systems resulted in significantly less debris extrusion than the PTU system.

Evaluation of apically extruded debris during root canal retreatment with two different rotary systems followed by a self-adjusting file.

PURPOSE: To compare the amount of apically extruded debris during root canal retreatment using ProTaper retreatment system (Dentsply Maillefer, Ballaigues, Switzerland), ProTaper retreatment system with Self-Adjusting File (SAF) system (ReDent-Nova, Ra'anana, Israel), Mtwo retreatment system (VDW, Munich, Germany), Mtwo retreatment system with SAF instruments. METHODS: In total, 72 extracted human mandibular incisor teeth were used. All root canals were prepared with ProTaper universal (Dentsply Maillefer) up to F2 file and filled with gutta percha and AH plus sealer using cold lateral condensation before being assembled randomly into 4 groups (n = 18 each). Root canal filling materials were removed using the ProTaper retreatment system, the ProTaper retreatment system followed by SAF system, Mtwo retreatment system and Mtwo retreatment system followed by SAF system. Debris extruded apically during the removal of canal filling material was collected into preweighed Eppendorf tubes. The tubes were then stored in an incubator at 70°C for 5 days. The weight of the dry extruded debris was established by subtracting the preretreatment and postretreatment weight of the Eppendorf tubes for each group. The data obtained were analyzed using Kruskal-Wallis test. RESULTS: All retreatment techniques caused the apical extrusion of debris. There was no significant difference between the groups statistically (p>0.05). CONCLUSIONS: The results of this study showed that SAF system after Mtwo retreatment system and ProTaper retreatment system for improving retreatment has no significant effect on the amount of debris extruded apically.