The effects of alternate irrigation of root canals with chelating agents and sodium hypochlorite on the effectiveness of smear layer removal

Abstract

Background. After the mechanical preparation of a root canal, the canal walls are covered with a smear layer. In order to deeply clean the dentinal tubules, removal of the smear layer is recommended. There is no consensus on the length of time of rinsing with chelating agents or irrigation with alternating chelating agents and sodium hypochlorite (NaOCl). Objectives. The aim of the study was to evaluate the effectiveness of smear layer removal using 4 irrigation protocols. Material and methods. We prepared 42 straight root canals to size ISO40/04 and assigned them into 4 study groups (n = 10) and a control group (n = 2). The root canals were irrigated as follows: in the control group, 180 s with 5.25% NaOCl; in group 1, 60 s with 40% citric acid (CA) and 120 s with NaOCl; in group 2, 120 s with CA and 120 s with NaOCl; in group 3, 30 s CA, 30 s with NaOCl, 30 s CA and 120 s with NaOCl; and in group 4, 60 s with CA, 30 s with NaOCl, 60 s with CA, and 120 s with NaOCl. The roots were split longitudinally and the root canals were observed under ×200-500 magnification. The root canal walls were analyzed in areas 2 mm, 6 mm and 10 mm from the apex. Results. In the apical and medial sections, the best effects were achieved in groups 3 and 4. In coronal sections, no significant differences between experimental groups were found. Conclusions. Within the limitations of this study, it can be concluded that irrigation with alternating NaOCl and CA was the most effective at smear layer removal, regardless of the irrigation time.

Effect of sodium hypochlorite, isopropyl alcohol and chlorhexidine on the epoxy sealant penetration into the dentinal tubules

“…A previous study conducted by the authors shows that this protocol is highly effective in removing the smear layer. 16 After removing the smear layer, the canals were irrigated with NaOCl to dissolve the exposed (due to demineralization) protein structures. For the final irrigation in group 2, NaOCl was used; NaOCl spontaneously decomposes into a hyperosmotic sodium chloride solution after a few minutes.…”

Endodontic treatment regimens and their application in practice - survey and comparative study

“…The question about the rinsing protocol met with a wide variety of answers. This is probably due to lack of standardization of root canal irrigation regimens [7,8,9]. This study showed that the most commonly used rinsing sequences are:…”

“…In addition, the printed form was delivered to dental practices. The worksheet contains two sections, the first relating to the demographics and biographies of the practitioners (1)(2)(3)(4), and the second relating to the methods, tools, and resources used in endodontic treatment (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20). The questions in the survey were single and multiple choice; in addition, question number 17 was an open-ended question.…”

“…According to the recommendations of the Research Department of the Polish Endodontic Society [7] rinsing protocol should be based on citric acid (40%) and sodium hypochlorite (5, 25) terminated with 2% chlorhexidine; K. Olczak [8] suggests the initial use of NaOCl with ultrasound, which would be combined with EDTA or citric acid, and the entire rinsing would be ended with alcohol or saline. Other sources indicate that the most effective sequence in terms of removing the smear layer is the alternating use of sodium hypochlorite and citric acid [9]. Also, despite clear guidelines published in 2006, a lot of controversy arises about the choice of the most effective method of root canal preparation.…”

The impact of irrigation protocols on epoxy sealer penetration depth in dentinal tubules. Study involving laser confocal microscopy

“…Removal of the smear layer in Groups 2 and 3 was achieved using double alternating irrigation with citric acid and sodium hypochlorite. The authors' previous study shows that this approach to canal irrigation is advantageous in removing the smear layer (20). Further quick rinsing of the root canals (in these groups) with citric acid was introduced in order to deactivate the sodium hypochlorite.…”