TECHNICAL NOTE Use of a bottle warmer to increase 4% sodium hypochlorite tissue dissolution ability on bovine pulp Giampiero Rossi-Fedele, DDS, MClinDent and Jose A. P. De Figueiredo, DDS, MSc, PhD Unit of Endodontology, UCL Eastman Dental Institute – University College London, London, UK Keywords baby equipment, dental pulp, sodium hypochlorite, heat, tissue dissolution. Correspondence Dr Jose A. P. De Figueiredo, Unit of Endodontology, UCL Eastman Dental Institute – University College London, 256 Gray’s Inn Road, London WC1X 8LD, UK. Email: j.figueiredo@eastman.ucl.ac.uk doi:10.1111/j.1747-4477.2007.00110.x Abstract The aim of this study was to evaluate the tissue dissolution ability of 4% sodium hypochlorite at increasing temperatures with the use of a baby bottle warmer. Twenty pieces of bovine pulp tissue from freshly extracted incisors and canines were weighted and randomly distributed among four groups in accordance to the exposure to 4% sodium hypochlorite at different tempera- tures: group C – room temperature (20.5°C – control); group T1 – 45°C; group T2 – 60°C; group T3 – 75°C. The samples were placed within test tubes when the solution reached the desired temperature. Time taken for the dissolution was recorded. One-way ANOVA with logarithmical transformation and Duncan post-hoc was used (P = 0.05). There was a statistically significant increase in speed of pulp dissolution from group T1 to group C and from groups T2 and T3 to group T1; group T2 and T3 displayed similar dissolution speeds. Introduction Root canal treatment involves, among other procedures, chemo-mechanical preparation of the system making use of irrigants. Different roles have been suggested for these lubricants, including: lubrication, debris removal, antimi- crobial action and tissue dissolution. Considering the morphologic complexity of most root canals, removal of all necrotic pulp tissue during the mechanical preparation is an almost impossible task. Among the different solu- tions suggested, only sodium hypochlorite has been shown to have the latter function (1–3). The increase in temperature of low concentration sodium hypochlorite has been advocated to achieve the similar effects of high concentration solutions, with the benefit of reducing the risks associated with its toxicity (4). The speed of pulp tissue dissolution from the irrigat- ing solution needs to be considered, bearing in mind that any pulp remnant in the root canal might be associated with treatment failures (4). Postoperative pain is more prevalent in vital pulpectomy than in non-vital cases, which may be due to pulp tissue remaining in the root canal (5). There is a need to improve the tissue dissolution effi- cacy of solutions presently used in endodontic treatment. The concentration has proven to be an important factor in this for sodium hypochlorite. However, the use of high concentration hypochlorite together with temperature rise is still not completely understood. The use of bottle warmers in endodontics is an easy way to provide heat to solutions used as irrigants. However, its use has been empirical and the benefit of such devices has not been thoroughly assessed. The purpose of this study was to analyse the bovine pulp dissolving ability of high concentration sodium hypochlorite at increasing temperatures provided by a bottle warmer. Materials and methods Twenty fragments obtained from bovine teeth were used in this study. The animals were less than 1 year old, slaughtered for commercial purpose, exerting no influ- ence on the animal’s fate at any stage. The teeth were frozen and left overnight at room temperature (approxi- mately 20°C) to thaw. The teeth were split and pulp removed, then divided into fragments using a #12 scalpel blade (Swann – Morton, Sheffield, UK) and weighted using precision scales (Sartorius BP61S, Goettingen, Germany). The immersion of the fragments into the test Aust Endod J 2008; 34: 39–42 39 © 2008 The Author Journal compilation © 2008 Australian Society of Endodontology