Effect of Apical Size and Taper on the Efficacy of Root Canal Disinfection With LED Photodynamic Therapy as an Adjunct to Irrigation With Sodium Hypochlorite

Abstract

Introduction: This study assessed the effect of apical size and taper on the efficacy of root canal disinfection with LED photodynamic therapy (PDT) as an adjunct to irrigation with sodium hypochlorite. Methods: A total of 126 extracted human mandibular molars were divided into 4 groups. The mesiobuccal canal was prepared to size 25/4% in group 1, 25/6% in group 2, 30/4% in group 3, and 30/6% in group 4 using the iRaCe rotary system. A 21-day Enterococcus faecalis biofilm was prepared and used for inoculation of the canals. Each group was randomly divided into 3 subgroups for canal disinfection with 2.5% sodium hypochlorite, sodium hypochlorite plus LED PDT and saline (positive control). Samples from the root canals were obtained with rotary files and cultured. Microbiologic data were analyzed using the Poisson regression test. Results: The bacterial count significantly decreased following disinfection with sodium hypochlorite with/without PDT in all sizes and tapers of preparation compared with the control group (P<0.05). Increasing the apical taper or apical size and the use of PDT as an adjunct did not have a significant effect on the reduction of the bacterial count (P>0.05). However, the apical size and PDT had a significant effect on the number of residual bacteria (P<0.05), and increasing the apical size and conduction of PDT significantly decreased the number of residual bacteria. Conclusion: The apical size and taper and the use of PDT as an adjunct did not have a significant effect on the reduction of the bacterial count. However, increasing the apical size and conduction of PDT as an adjunct to sodium hypochlorite irrigation significantly decreased the number of residual bacteria in the root canal system.

Effectiveness of conservative instrumentation in root canal disinfection

“…In this study, conservative root canal shaping with TN and Rotate reduced the microorganisms to a degree similar to PTG, regardless of the curvature. The higher taper in the PTG group did not affect the root canal cleanliness, a finding in line with previous reports of similar debris [9] and bacterial reduction [39] using different tapers. One study did find that increasing the taper from 4 to 8% caused a significant difference in the number of residual bacteria [40].…”

The effect of root canal preparation tapers on planktonic bacteria and biofilm reduction in the apical third: A correlative microtomography and microbiological laboratory study

“…The difference in the taper of the instruments did not result in different levels of disinfection in the apical region, confirming a previous study in which the amount of infected residual dentin and the smear layer in the apical third of the root canals were not significantly affected by preparations with 0.04 or 0.06 tapers and the same apical diameter (Plotino et al, 2019). Other studies examining bacterial reduction and different tapers agree with these results (Alimadadi et al, 2021;Usta et al, 2023). The results of the present study contradict previous studies that recommended the use of 30-tip instruments for efficient penetration of the irrigant into the apical third (Khademi et al, 2006;Usman et al, 2004).…”