Real-Time Three-dimensional Dynamic Navigation for Post Space Preparation in Root Canal-Treated Teeth: An In vitro Study.

INTRODUCTION: The aim of this study was to investigate the feasibility of a real-time three-dimensional dynamic navigation system (3D-DNS) for post space preparation (PSP) in root canal-treated teeth and to compare the accuracy and efficiency of 3D-DNS to freehand (FH) for PSP. METHODS: Fifty-four maxillary molars were divided into two groups: 3D-DNS (n = 27) and FH group (n = 27). Cone beam computed tomography (CBCT) scans were taken preoperatively and postoperatively. The drilling path for the PSP was virtually planned in the preoperative CBCT scan in the X-guide software (X-Nav Technologies, Lansdale, PA). For the 3D-DNS group, the PSP drilling was conducted under dynamic navigation. The 3D deviations and angular deflections were calculated. The residual dentin thickness (RDT) was determined after PSP. The operation time and the total number of mishaps were recorded. Shapiro-Wilk, t-test or Mann-Whitney rank sum, weighted Cohen's kappa, and Fisher exact tests were used (P < .05). RESULTS: The PSP was completed in all samples (54/54). The 3D-DNS was more accurate than the FH, with significantly fewer 3D deviations and angular deflections (all, P < .05). The 3D-DNS required less operating time than the FH (P < .05). For the 3D-DNS, no teeth had RDT < 1 mm, whereas 6/27 in the FH showed RDT < 1 mm after the PSP. There was no difference in the total number of mishaps (P > .05). CONCLUSION: Within the limitations of this in vitro study, the 3D-DNS is feasible for PSP. The 3D-DNS improved the accuracy and efficiency of PSP. The dynamic navigation system can potentially become a safe and reliable technology for PSP.

Efficacy of reciprocating systems for removing root filling material plus complementary cleaning methods in flattened canals: Microtomography and scanning electron microscopy study.

The aim of this study was to evaluate three reciprocating systems and complementary cleaning methods on filling material removal during retreatment of flattened canals. Thirty-six mandibular incisors were prepared using rotary instruments up to size 25.08 and filled using the single-cone technique. Subsequently, the teeth were divided into three groups (n = 12) according to retreatment procedures: Reciproc Blue (RB): 25/0.08 and 40/0.06; ProDesign R (PDR): 25/0.06 and 35/0.05; and WaveOne Gold (WOG): 25/0.07 and 35/0.06. The remaining filling volume materials were assessed by means of micro-CT imaging before and after retreatment. After this, the specimens were subdivided into three groups according to complementary cleaning methods: XP-Endo Shaper (30/0.01); passive ultrasonic irrigation (PUI); 60° oscillatory instrumentation with #30 H-file, and micro-CT scan was taken. Then, the roots were cut in half and the samples were analyzed by scanning electron microscope (SEM). The data were analyzed statistically using Kruskal-Wallis and Dunn's Multiple Comparison test with significance level of 5%. None of the reciprocating files promoted complete removal of filling material and there was no statistical difference between the groups, regardless instrument size (p > 0.05). Complementary cleaning methods increased remnant filling removal (p < 0.05). XP-endo Shaper significantly reduced the amount of filling material in the apical and middle thirds, compared with H-files (p < 0.05), with no difference with PUI. In the SEM, there was no statistical difference among the instruments (p > 0.05). The reciprocating systems showed similar effectiveness in removing root filling material. Complementary cleaning method with the XP-Shaper enhanced filling material removal.

Avaliação da precisão de dois localizadores foraminais na determinação do limite apical: estudo in vitro / Evaluation of the accuracy of two apex locators in determining apical limit: an in vitro study

O objetivo do presente estudo foi comparar in vitro a precisão de dois localizadores foraminais: Endus (Gnatus, Ribeirão Preto, SP, Brasil) e Root ZX (J. Morita, Tokyo, Japão). Material e Método: Trinta e dois dentes caninos permanentes humanos foram selecionados para o estudo. Após a realização da abertura coronária e preparo do terço cervical e médio, procedeu-se à determinação do comprimento real do dente pelo método visual, com introdução de um instrumento tipo K #10 até ser visto na saída foraminal sob magnificação de 16x com microscópio óptico de luz (DF Vasconcelos, São Paulo, Brasil). Para medição eletrônica, os dentes foram inseridos em um molde de alginato e as medidas realizadas com os dois localizadores foraminais até a saída do forame apical (0,0mm). Resultados: Os resultados evidenciaram um índice de precisão de 96,8% e 91,6% para os localizadores Gnatus e Root ZX, respectivamente. Conclusão: Ambos os localizadores apicais eletrônicos testados apresentaram alto índice de precisão na determinação do limite apical.

The aim of this study was to compare in vitro the precision of two locators foraminal: Endus (Gnatus, Ribeirão Preto, SP, Brazil) and Root ZX (J. Morita, Tokyo, Japan). Methods: Thirty-two canine teeth permanent humans were selected for the study, and, after effectuate the coronary opening and preparation of the cervical and middle third, proceeded to the determination of the real length of the tooth by the visual method, introducing an instrument file K #10 until be seen in foraminal exit under magnification of 16x optical light microscope (DF Vasconcelos, São Paulo, Brazil). For electronic measurement, the teeth were embedded in an alginate mold and electronic measurements with the two locators foraminal to the actual output of the apical foramen (0,0mm). Results: The results showed a 96.8% and 91.6% accuracy rates for the locators Gnatus and Root ZX, respectively. Conclusion: Both electronic apex locators tested presented high index of precision in the precise of determination in the apical limit.

Influence of embedding media on the assessment of electronic apex locators.

Third-generation electronic apex locators for root canal length determination are very reliable and are not subject to interference from the contents of the canals. This study compared the effectiveness of different embedding media for in vitro assessment of electronic apex locators. The tooth lengths of 30 extracted human mandibular central incisors were measured by introducing a size 15 K-file fitted with a silicone stop into the canal until its tip appeared through the apical foramen; the distance between the tip and stop was measured. The teeth were placed in cylindrical polyethylene tubes filled with different embedding media (1% agar, gelatin, alginate, saline, and flower sponge soaked in saline), and electronic reading was performed with the Root ZX device. Data were statistically assessed by the analysis of variance (ANOVA) and Tukey tests at a significance level of 5%. Despite the lack of statistically significant difference among the media, the flower sponge was the only medium in which the file surpassed the apex in some measurements.

Evaluation of apical cavity preparation with a new type of ultrasonic diamond tip.

This study evaluated the time, occurrence of fracture, and quality of apical cavity preparation with three different ultrasonic diamond tips: Satelec, Trinity, and a new type, CVD (chemical vapor deposition), using scanning electron microscopy (SEM) analysis. Thirty human single-rooted premolars were selected, submitted to apicectomy, and prepared with ultrasonic tips; impressions were then obtained. The presence of fractures was evaluated on the impressions, and the quality of preparation was evaluated by SEM analysis of teeth and scoring by two examiners. The group prepared with the CVD tips exhibited the shorter preparation time and did not present fractures. There was no statistically significant difference in the quality of preparation for the three tips. The three brands of ultrasonic tips produced adequate grinding without altering the morphology of the apical foramen.