Success in root canal therapy depends on complete bacterial debridement, pulp tissue elimination and fine cleaning-shaping of root canal. In some cases the endodontic therapy procedure is not completed in one visit, so a temporary filling material is necessary (1). Lack of proper temporary filling is the second pain remaining factor after treatment (2). Temporary filling material must provide adequate canal seal against bacterial, organic material and oral fluids, preserve tooth remaining structure, have acceptable aesthetic and easy handling (3). Among temporary filling materials, reinforced zinc oxide eugenol and calcium sulfate based materials are more common. Coltosol, Cavit and Kalzinol are common temporary filling brands (4). In 2005 Laustsen et al. claimed that Coltosol F causes cusp deflection, infraction and fracture, if used as a temporary filling material in endodontically treated teeth (5). Lubbers- Coltene chief- disapproved Laustsen results about Coltosol F because of inappropriate method in their study (6). The aim of this study was the evaluation of cusp deflection, infraction and fracture in endodontically treated teeth that were filled with three filling material: Cavisol (golchai, iran), Coltosol F (coltene, swiss) and Coltene (aria dent, iran).
Materials and Methods
Forty five human premolars (thirty maxillary and fifteen mandibular second premolars) extracted for orthodontic treatment with the same size were chosen. Teeth were evaluated under stereomicroscope to be free of caries and cracks. Access cavity prepared for root canal therapy. Canal shaping was done in passive step back method with K files (Mani, Tochigi, Japan). The master apical file was number 30 and working length was one millimeter to the apex. Master cone was number 30 gutta-percha (Aria dent,Tehran,Iran) and lateral condensation method used for canal ubturation. Gutta-percha were cut from orifice. Then MOD cavity prepared in teeth with 4 millimeter Bucco-lingual width, 6 millimeter depth and 1 millimeter above CEJ line and tried to keep pulpal and gingival floor at the same level.
Then teeth divided into three groups of fifteen teeth (ten maxillary and five mandibular premolars). One group filled with Coltosol F, the other with Coltene and last group with Cavisol.
Reference points marked on buccal and lingual cusp tips by needle bars. Samples were kept in normal saline solution at room temperature except for measurement procedure. Thermocycling was done for 700 cycles.
Teeth were observed under stereomicroscope (Zeiss,Jena, Germany) with 20X magnification lens. Two plates and putty used to fix the distance between cusp tips and microscope lens the same for all samples. The photo of each tooth saved in PC and then observed in Photoshop software. The measurement procedure was done every day by two observers for 20 days. Every day, they measured intercuspal distance and if their findings were different from the, the mean number was noted as the right distance. At the end of the 20th day, teeth were transferred to methylene blue 1% for 48 hours, washed then thoroughly and existence of cracks was determined for each tooth which now colored in blue.
Repeated-measures ANOVA test used to evaluate the percent of expansion for each temporary filling material. . Mann-Whitney U and Chi-square tests used for comparison of expansion between each two groups and existence of cracks in respect.