Influence of apical enlargement in cleaning and extrusion in canals with mild and moderate curvatures

Abstract

Optical microscopy and morphometric analysis were used in this study to evaluate, in vitro, the cleaning of the apical region in root canals with mild or moderate curvatures subjected to biomechanical preparation with a rotary system, as well as to assess the amount of extruded material to the periapical area. Lateral incisors (n = 32), 16 with curvature angles smaller or equal to 10° (GI) and 16 between 11° and 25° angles (GII) were submitted to Hero 642 rotary instrumentation with different surgical diameters: (A) 30.02 and (B) 45.02. Irrigation was performed at each change of instrument with 5 mL of ultrapure Milli-Q water and the extruded material through the apical foramen was collected. Root cross-sections were subjected to histological analysis by optical microscopy (×40) and the images were evaluated morphometrically using the Image Tool software. Quantification of the extruded material was performed by weighing after liquid evaporation. ANOVA showed no statistically significant differences (p>0.05) among the groups with respect to the procedures used to clean the apical region. Considering the amount of extruded material, the Tukey's HSD showed that canals with mild curvature prepared with the 45.02 surgical diameter showed significantly higher values (p<0.05) that those of the other groups, which were similar between themselves (p>0.05). In conclusion, the effect of cleaning the apical region did not differ in the groups, considering root curvature and the surgical diameter of instruments used for apical preparation. The amount of extruded material was greater in canals with mild curvature that were prepared with the 45.02 surgical instrument diameter.

Apical Extrusion of Debris and Irrigants Using Different Irrigation Needles

“…The results also indicate that root canal curvature was not a factor affecting the amount of periapical debris extrusion, despite prior studies finding that straight or mildly curved root canals generate a higher irrigation pressure than moderate or highly curved canals. Such findings agree with Psimma et al (9), but contradict those of Borges et al (15), who demonstrated that root canals curved between 10° and 25° and apically prepared with #45.02 instruments had increased periapical irrigant and debris extrusion. Importantly, this contradiction may reflect the investigator's use of anterior teeth, which present improved foramen alignment with the root long axis (21).…”

“…Most in vitro extrusion studies do not attempt to simulate adjacent vital pulp or periapical tissues (3,14,15). Yet, these tissues act as a natural barrier preventing or diminishing debris extrusion and therefore, such results should not be directly extrapolated at the dental clinic.…”

Influence of apical preparation size and irrigation technique on root canal debridement: a histological analysis of round and oval root canals

“…Studies on this topic have investigated the influence of apical preparation size on root canal cleanliness (Benatti et al 1985, Usman et al 2004, Khademi et al 2006, Fornari et al 2010, Borges et al 2011, microbial reduction (Ørstavik et al 1991, Yared & Dagher 1994, Card et al 2002, Coldero et al 2002, Rollison et al 2002, Mickel et al 2007, Rodrigues et al 2017 or healing outcome (de Souza Filho et al 1987, Saini et al 2012, Souza et al 2012, after preparation with instruments and irrigation using a syringe and a needle. Only one study compared a size 20, .04 preparation with a size 25, .04 preparation in conjunction with sonic activation (Plotino et al 2018), concluding that the size 25 resulted in cleaner canals, despite the presence of debris.…”

Ex vivo post-instrumentation qualitative evaluation comparing three techniques: Step Back - Oregon modified by F.O.B - Protaper Rotary Technique

“…Mediante los resultados obtenidos y la literatura investigada, parece no haber duda, en el momento actual, de la inexistencia de instrumentos y técnicas capaces de promover la desinfección completa de los sistemas de conductos radiculares (27)(28)(29)(30).…”