Necrotic pulp tissue dissolution by passive ultrasonic irrigation in simulated accessory canals: impact of canal location and angulation

Abstract

AIM: To evaluate whether passive ultrasonic irrigation (PUI) of 2.5% NaOCl would dissolve necrotic pulp tissue from simulated accessory root canals (SACs) better than passive placement of the irrigant, when temperature was equilibrated between the two treatments. METHODOLOGY: Transparent root canal models (n = 6) were made from epoxy resin. SACs of 0.2 mm diameter were placed at defined angles and positions in the mid-canal and apical area. SACs were filled with necrotic bovine pulp tissue. PUI was performed five times for 1 min each with irrigant replenishment after every minute. Main canal temperature was measured after each minute, and a digital photograph was taken. In control experiments, mock treatments were performed with the same set-up without activation of the file using heated NaOCl to mimic the temperature created by PUI. Experiments were repeated five times. Digital photographs were analysed for the distance of dissolved tissue into the SACs in mm. Overall comparison (sum of dissolved tissue from all five accessory canals) between treatments was performed using paired t-test. Differences between SAC angulation and position after PUI were investigated using anova/Bonferroni (alpha < 0.05). RESULTS: Passive ultrasonic irrigation caused a rise in irrigant temperature in the main canal to 53.5 +/-2.7 degrees C after the fifth minute. PUI dissolved a total of 6.4 +/-2.1 mm, mock treatment controlled for heat: 1.4 +/-0.6 mm (P < 0.05). No significant influence of SAC position or angulation was found. CONCLUSIONS: Passive ultrasonic irrigation promotes positive tissue-dissolving effects beyond a rise in irrigant temperature. AbstractAim To evaluate whether passive ultrasonic irrigation (PUI) of 2.5% NaOCl would dissolve necrotic pulp tissue from simulated accessory root canals (SACs) better than passive placement of the irrigant when temperature was equilibrated between the two treatments.Methodology Transparent root canal models (N = 6) were made from epoxy resin. SACs of 0.2 mm diameter were placed at defined angles and positions in the mid-canal and apical area.SACs were filled with necrotic bovine pulp tissue. PUI was performed for five times 1 min with irrigant replenishment after each min. Main canal temperature was measured after each min, and a digital photograph was taken. In control experiments, mock treatments were performed with the same set-up without activation of the file using heated NaOCl to mimick the temperature created by PUI. Experiments were repeated 5 times. Digital photographs were analysed for the distance of dissolved tissue into the SACs in mm. Overall comparison (sum of dissolved tissue from all 5 accessory canals) between treatments was performed using paired t-test. Differences between SAC angulation and position after PUI were investigated using ANOVA/ Bonferroni (alpha < 0.05).

Review of ultrasonic irrigation in endodontics: increasing action of irrigating solutions

“…However, it did not become popular until 1955, the year when a new application was introduced using US to remove calculus deposits and plaque from teeth surfaces. Despite the fact that US is used in dentistry for therapeutic and diagnostic purposes and also for cleaning instruments before sterilisation, the main use until recently has been for scraping and smoothing the root surfaces of teeth and root canal treatment (6,8). …”

“…In comparison to sonic irrigation, ultrasonic irrigation has proved to be more powerful and able to eliminate more debris, and so it is claimed that passive ultrasonic irrigation is significantly more efficient than sonic activation (8). However, both techniques may clean the canal system to a similar degree when sonic irrigation is applied for a longer time (5,13,18).…”

“…It has been shown that irrigants can only progress 1 mm beyond the tip of the needle. Increased volume does not significantly improve cleaning action or detritus elimination (8). …”

“…Two flushing methods can be used during PUI, continuous or intermittent flush of the irrigant (8). The continuous flush technique provides an uninterrupted supply of fresh irrigation solution in the root canal.…”

The cleaning efficiency of the root canal after different instrumentation technique and irrigation protocol: A SEM analysis

“…Traditional needle irrigation alone demonstrated significantly less penetration of irrigant into the lateral canals and was limited to the level of penetration of the needle. Passive ultrasonic irrigation cause a rise in irrigant temperature in the main canal to 53.5˚C ± 2.7˚C after the fifth minute, irrigation promotes positive tissuedissolving effects beyond a rise in irrigant temperature [41]. Irrigation with sodium hypochlorite increase tooth surface strain.…”