# Evaluation of pH and Optical Properties of Dual Ringe HEDP Irrigating Solution
[PERSON]  
1 Department of Chemistry, Faculty of Medical Sciences, University of Kragujevac, 34000 Kragujevac, Serbia; [EMAIL_ADDRESS] (A.S.); [PERSON] (M.V.P. ); [EMAIL_ADDRESS] (S.Z. ); [EMAIL_ADDRESS] (M.P.) [PERSON]  
1 Department of Chemistry, Faculty of Medical Sciences, University of Kragujevac, 34000 Kragujevac, Serbia; [EMAIL_ADDRESS] (A.S.); [PERSON] (M.V.P. ); [EMAIL_ADDRESS] (S.Z. ); [EMAIL_ADDRESS] (M.P.) [PERSON]  
1 Department of Chemistry, Faculty of Medical Sciences, University of Kragujevac, 34000 Kragujevac, Serbia; [EMAIL_ADDRESS] (A.S.); [PERSON] (M.V.P. ); [EMAIL_ADDRESS] (S.Z. ); [EMAIL_ADDRESS] (M.P.) [PERSON]  
1 Department of Chemistry, Faculty of Medical Sciences, University of Kragujevac, 34000 Kragujevac, Serbia; [EMAIL_ADDRESS] (A.S.); [PERSON] (M.V.P. ); [EMAIL_ADDRESS] (S.Z. ); [EMAIL_ADDRESS] (M.P.) [PERSON]  
1 Department of Chemistry, Faculty of Medical Sciences, University of Kragujevac, 34000 Kragujevac, Serbia; [EMAIL_ADDRESS] (A.S.); [EMAIL_ADDRESS] (M.V.P. ); [EMAIL_ADDRESS] (S.Z. ); [EMAIL_ADDRESS] (M.P.) [PERSON]  
1 Department of Chemistry, Faculty of Medical Sciences, University of Kragujevac, 34000 Kragujevac, Serbia; [EMAIL_ADDRESS] (A.S.); [EMAIL_ADDRESS] (M.V.P. ); [EMAIL_ADDRESS] (S.Z. ); [EMAIL_ADDRESS] (M.P.) [PERSON]  
1 Department of Chemistry, Faculty of Medical Sciences, University of Kragujevac, 34000 Kragujevac, Serbia; [EMAIL_ADDRESS] (A.S.); [EMAIL_ADDRESS] (M.V.P. ); [EMAIL_ADDRESS] (S.Z. ); [EMAIL_ADDRESS] (M.P.) [PERSON]  
1 Department of Chemistry, Faculty of Medical Sciences, University of Kragujevac, 34000 Kragujevac, Serbia; [EMAIL_ADDRESS] (A.S.); [EMAIL_ADDRESS] (M.V.P. Based on the effects they produce, irrigating solutions are divided into groups of antiseptics and chelating agents [1]. Most notable antiseptics are chlorhexidine (CHX) and sodium hypochlorite (NaOCI). The latter is commonly used due to its antimicrobial activity, tissue-dissolving properties, detergent role, and ability to neutralize toxic by-products [5; 6]. However, antiseptics lack the capability to remove the smear layer. Therefore, chelating agents such as 15-17% Ethylenediaminetetraacetic acid (EDTA) and 10-20% citric acid (CA) are additionally introduced to irrigation protocols [1; 3]. It is recommended to alternate the use of both groups of irrigating solutions during mechanical preparation [3], which led to the development of various combined irrigants with debatable effectiveness [7; 8; 9; 10; 11]. HEDP (1-hydroxyethylene 1,1-disphosphonate), also known as eidronic acid, belongs to the group of chelating agents that is commercially available as Dual Rinse HEDP [12; 13]. It can be utilized independently, where it produces a mild chelating effect, or in combination with NaOCI for a procedure known as continuous chelation irrigation [13; 14]. This combination retains the desired antimicrobial and proteolytic effects of NaOCI whilst adding an element of decalcification to the mixture and simplifying the procedure [12; 13; 14; 15]. The chemical efficacy of irrigants is influenced by various factors, with pH value emerging as a significant one. The pH of the solution has been demonstrated to affect the tissue-dissolving, antimicrobial, and chelating properties of diverse irrigants [16; 17]. Furthermore, combining NaOCI with other solutions is shown to alter its pH values, thereby modifying the effectiveness of this solution [18; 19]. To date, studies on the combination of HEDP with NaOCI have mostly shown an alkaline pH for this mixture [20; 21; 22]. However, these results were often arising from the application of chemically synthesized eidronate rather than the commercial product, as well as different solutions or concentrations of NaOCI with distinct pH values. The properties of the sole irrigating solutions are not sufficient to achieve the desired disinfection of the canal. Another pivotal factor in the efficiency of irrigants is their activation in the root canal.