Microscopic and statistical evaluation of the marginal defects of composite restorations: in vitro studies.

This study aimed to evaluate the quality of dental restorations using laboratory microscopic techniques, focusing on the positioning of restorations relative to cavity edges and identifying common errors, such as incomplete or excessive coronal restorations. A total of 41 extracted lateral teeth, previously treated in vivo with Class I or II composites, were analyzed. Thirty-three of these teeth were sectioned medio-distally or buccal-orally and examined under a research laboratory microscope. Marginal areas were measured using eyepieces with a graduated scale and calibration slide, and a frequency statistical analysis was conducted. The analysis revealed that the teeth had fractious edges, deficient marginal closure, excess composite, incorrectly restored occlusal cusps, and marginal adaptation errors, with approximately half of these errors involving excess material. It was observed that restoration procedures in distal areas are particularly challenging, and clinical errors with excess material occur more frequently than those with a deficit. These findings underscore the need for improved techniques and precision in dental restorations to minimize such errors.

Optical microscopy evaluation of root canal filling removal by beginner operators in posterior teeth.

This study analyzed the effectiveness of root canal filling removal in lower molars performed by beginner operators using optical microscopy. A total of 55 mandibular first and second molars with mesial roots exhibiting an average curvature of 10-20° were selected based on preoperative radiographs. Instrumentation was done with ProTaper Gold (Dentsply Sirona) up to F2 (25/.08), using 2ml of 2.5% NaOCl irrigation solution after each file. Root canal obturation was performed using gutta-percha points with cold lateral condensation and Sealapex (Kerr Dental). Coronal fillings were made with composite resin and stored in distilled water for two years. Removal of the root canal fillings was performed with AF Retreatment Rotary (AFRR) and AF Blue R3 (AFBR3) (Fanta Dental Materials) under reciprocating motion with 2.5% NaOCl irrigation. Cross-sections of the coronal, middle, and apical thirds were analyzed at 40x magnification using a STEINDORFF POL microscope with a digital camera. Image analysis was conducted using Image J software, version 1.54, to determine the efficiency of root canal filling removal by percentage. Statistical analysis via one-way ANOVA revealed significant differences between distal and mesial roots (P < 0.05). Specifically, for mesial roots, the removal efficiency was 70.65% in the coronal third, 54.66% in the middle third, and 21.32% in the apical third. Significant difficulties were noted due to fractured files, calcifications, and debris accumulation in the isthmuses. The study concluded that the protocol using Fanta files demonstrated significant differences in removal efficiency correlated with root curvature, compounded by the inexperience of beginner operators. The findings highlight the challenges faced by novice practitioners in achieving effective root canal filling removal.

Evaluation of the sealer/gutta-percha ratio on sets of root section surfaces of some extracted teeth sealed using the cold lateral condensation technique.

Canal filling must be well adapted to the walls of the root canal to prevent bacterial infiltration. Endodontic seals play an essential role in ensuring tightness, without which the canal filling would suffer infiltrations. This study aimed to evaluate the areas occupied by the two components of the canal filling, as well as the sealer/gutta-percha ratio in the root canals of the maxillary central incisors after their filling using the cold lateral condensation technique with gutta-percha. Thirty extracted upper central incisors were rotatably prepared with ProTaper Universal up to F3 and sealed using the cold lateral condensation technique with gutta-percha. After setting the sealer, the roots of the teeth were sectioned perpendicularly to 1 (L1), 3 (L3), 6 (L6), and 8 (L8) mm from the apex. The surface of the sections was analyzed with a Leica EZ4D stereomicroscope and photographed at two magnification orders: 10x and 25x. The areas corresponding to the gutta-percha, sealer, gaps, and root canal were expressed in pixels using the ImageJ software, version 1.50i. The difference in the representation of sealer areas, gutta-percha and voids was statistically significantly different for all four sections analyzed. The best adaptation of the canal obturation was observed in L1 and L3. The gutta-percha area was statistically significantly higher than that of the sealer for the L1, L3, and L6 levels, while the sealer/gutta-percha ratio recorded the lowest value at the L3 level (0, 30) and the highest at its L8 (0.70) level, without registering statistically significant differences regarding the area at the four analyzed levels. The voids were mostly absent or recorded a minimal percentage area (<1%). Cold lateral condensation of gutta-percha has led to a good adaptation of gutta-percha to the root canal wall, with a small amount of sealer, especially to the sections made at 3 mm from the apex. Given the limitations of this study, we noted that the voids were few - observed in the 6 and 8 mm sections - and were negligible in many cases.

Stereomicroscopic and Microscopic Study of Dental Structural Aspects Derived from Iatrogenic and Pathological Processes Suffered by a Second Mandibular Premolar - A Case Study.

Microscopic studies performed on extracted human teeth after their preparation in advance is helpful in a relatively good reestablishment of the treatment steps that have been applied to these teeth, as well as an evaluation of the quality of such treatments. Therefore, we have used stereo- and optical microscopy, highlighting aspects of external morphology, as well as root canal space of an extracted mandibular second premolar, subjected to prosthetic and endodontic treatment. In order to verify some technical errors that might occur during the endodontic and restorative treatment, we tried to appreciate the quality of the root canal filling and cervical defect and access cavity restoration of an extracted premolar #45.Without having the data from clinical records, we concluded that the method used for root canal filling was the warm lateral condensation technic; we also appreciated the quality of the fusion of the gutta-percha cones used, so the introduction of heated spreaders only in the central part of the bunch of cones makes it possible to clearly detect the boundaries between these cones towards the outside of the filling.