Effects of Chemical Agents on Physical Properties and Structure of Primary Pulp Chamber Dentin FERNANDA MIORI PASCON, 1 KAMILA ROSAMILIA KANTOVITZ, 1 JULIANA FRANCIELE GASPAR, 1 ANDREIA BOLZAN DE PAULA, 2 AND REGINA MARIA PUPPIN-RONTANI 1 * 1 Pediatric Dentistry Department, Piracicaba Dental School, University of Campinas, Piracicaba, S~ ao Paulo, Brazil 2 Operative Dentistry Department, Piracicaba Dental School, University of Campinas, Piracicaba, S~ ao Paulo, Brazil KEY WORDS dental pulp cavity; hardness; root canal irrigants; scanning electron microscopy ABSTRACT This study evaluated the effects of chemical agents on the physical properties and structure of primary pulp chamber dentin using surface roughness, microhardness tests, and scanning electron microscopy (SEM). Twenty-five primary teeth were sectioned exposing the pulp chamber and were divided into five groups (n 5 5): NT, no treatment; SH1, 1% sodium hypo- chlorite (NaOCl); SH1U, 1% NaOCl 1 Endo-PTC V R ; SH1E, 1% NaOCl 1 17% EDTA; and E, 17% EDTA. After dentin treatment, the specimens were submitted to roughness, microhardness test- ing, and SEM analysis. Roughness and microhardness data were submitted to one-way ANOVA and Tukey’s test (P < 0.05). The SH1E group showed the highest roughness, followed by the E group (P < 0.05) when compared with the NT, SH1, and SH1U groups. Microhardness values of SH1 and SH1U showed no significant difference as compared to the NT (control) group (P > 0.05). Microhardness values could not be obtained in the EDTA groups (SH1E and E). The presence of intertubular dentin with opened dentin tubules was observed in the NT, SH1, and SH1U groups. SH1E showed eroded and disorganized dentin with few opened tubules and the intertubular/peritubular dentin was partially removed. Considering the physical and structural approaches and the chemical agents studied, it can be concluded that NaOCl and NaOCl associ- ated with Endo-PTC V R were the agents that promoted the smallest changes in surface roughness, microhardness, and structure of the pulp chamber dentin of primary teeth. Microsc. Res. Tech. 77:52–56, 2014. V C 2013 Wiley Periodicals, Inc. INTRODUCTION Primary teeth with pulpal exposure or pathology must be treated by root canal treatment or extraction (Carrotte, 2005). The premature loss of primary teeth leads to undesirable tooth movements of primary and/ or permanent teeth, including the loss of arch length (Carrotte, 2005). Thus, maintaining arch length is important for good masticatory function and the future eruption of the permanent dentition with optimal occlusion development (Carrotte, 2005). Root canal treatment is a common dental procedure that is usually performed with mechanical debride- ment in the presence of chemical agents (McComb and Smith, 1975). Because irrigation with an inert solution cannot adequately reduce the microbial population in a root canal system, disinfection with other agents, such as NaOCl, is an important step in assuring the optimal bacterial decontamination of the canals (Zehnder, 2006). However, it has been reported that these agents are capable of causing alterations in the chemical composition of pulp chamber dentin, such as the inorganic content evaluated by Raman analysis (Borges et al., 2008) and the calcium/phosphorus ratio of the root canal dentin surface analyzed using induc- tively coupled plasma atomic emission spectrometry technique that measured the levels of five elements calcium, phosphorus, magnesium, potassium, and sulfur (Ari and Erdemir, 2005). Despite the study of Borges et al. (2008), little is known at present regarding the mechanical and structural properties of primary pulp chamber dentin after using chemical agents. This subject can be important to suggest the performance of adhesion in this substrate (pulp chamber/restorative material) and can help the pediatric dentists to choose a chemical agent that present lower alterations in the substrate and to enhance the adhesion process. In addi- tion, these alterations can be relevant for the long-term success of endodontics because they may affect the coro- nal bonding strength of dental materials (Kijsaman- mith et al., 2002; Santos et al., 2006). Knowledge of the mechanical properties is impor- tant to predict the behavior of the dentin/restoration interface and for understanding how endodontic proce- dures alter dentin strength. As microhardness is dependent on the composition and surface structure (Panighi and G’Sell, 1992), attention has been focused *Correspondence to: R.M. Puppin-Rontani; Pediatric Dentistry Department, Piracicaba Dental School, University of Campinas, Av. Limeira, 901, 13414-903 Piracicaba, SP, Brazil. E-mail: rmpuppin@fop.unicamp.br Received 21 April 2013; accepted in revised form 24 October 2013 REVIEW EDITOR: Dr. Chuanbin Mao DOI 10.1002/jemt.22312 Published online 12 November 2013 in Wiley Online Library (wileyonlinelibrary.com). V V C 2013 WILEY PERIODICALS, INC. MICROSCOPY RESEARCH AND TECHNIQUE 77:52–56 (2014)