Effect of root canal irrigant (sodium hypochlorite & saline) delivery at different temperatures and durations on pre-load and cyclic-loading surface-strain of anatomically different premolars. (September 2021)

• Record Type: Journal Article
• Authors: Gulabivala, K.; Azam, I.; Mahdavi-Izadi, S.; Palmer, G.; Georgiou, G.; Knowles, JC; Y-L, Ng
• Is Part Of: Journal of the mechanical behavior of biomedical materials. Volume 121(2021)
• Publication Date: 2021-09
• Subjects: Tooth surface strain -- Sodium hypochlorite -- Saline -- Irrigant temperature -- Pre-load strain -- Cyclic loading strain; Biomedical materials -- Periodicals; Biomedical materials -- Mechanical properties -- Periodicals; Biomedical materials; Biomedical materials -- Mechanical properties; Periodicals; Electronic journals; 610.28
• DOI: 10.1016/j.jmbbm.2021.104640
• Languages: English
• ISSNs: 1751-6161

Abstract

Abstract: Aim: To evaluate the effect of NaOCl (5%) and saline (control) irrigant delivery at different temperatures and durations on pre-load and cyclic-loading tooth-surface-strain (TSS) on anatomically different premolars. Method ology : Single-rooted premolars (n = 36), root-canal-prepared in standard manner, were randomly allocated to six irrigation groups: (A1) NaOCl-21 °C; (A2) NaOCl-60 °C; (A3) saline-21 °C then NaOCl-21 °C; (A4) saline-60 °C then NaOCl-21 °C; (A5) saline-21 °C then NaOCl-60 °C; (A6) saline-60 °C then NaOCl-60 °C. A1-2 received nine 10-min irrigation periods (IP) with NaOCl; A3-6 received nine 10-min IP with saline, followed by 9 IP with NaOCl at different temperature combinations. Premolars (n = 56) with single, fused or double roots prepared by standard protocol, were stratified and randomly allocated to: (B1) saline-21 °C; (B2) saline-80 °C; (B3) NaOCl-21 °C; (B4) NaOCl-80 °C. TSS (μє) was recorded pre-irrigation, post-irrigation and pre-load for each IP and during cyclic loading 2 min after each IP, over 30–274 min, using strain-gauges. Generalised linear mixed models were used for analysis. Results: Baseline TSS in double-rooted premolars was significantly ( p=0.001 ) lower than in single/fused-rooted-premolars; and affected by mesial-wall-thickness ( p=0.005 ). There was significant increase in loading-TSS (μє) after NaOCl-21 °C irrigation ( p=0.01 ) but decrease after NaOCl-60 °C irrigation ( p=0.001 ). TSS also increased significantly ( p = 0.005 ) after Saline-80 °C irrigation. Pre-load "strain-shift" was noted only upon first saline delivery but every-time with NaOCl. Strain-shift negatively influenced loading-TSS after saline or NaOCl irrigation (A3-6) but was only significant for saline-21 °C. Conclusions: Tooth anatomy significantly affected its strain characteristics, exhibiting limits within which strain changes occurred. Intra-canal introduction of saline or NaOCl caused non-random strain shifts without loading. Irrigation with NaOCl-21 °C increased loading tooth strain, as did saline-80 °C or NaOCl-80 °C but NaOCl-60 °C decreased it. A "chain-link" model was proposed to explain the findings and tooth biomechanics. Highlights: Measured effect of canal irrigation (type & temperature) on pre-load and loading surface-strain of premolars. Strain characteristics of different premolars were measured using cervical electrical strain gauges. Teeth exhibited anatomically-related strain limits influenced by irrigant and loading conditions. A "chain-link" model was proposed to explain the findings and tooth biomechanics.