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MTA Fillapex had the lowest push-out bond values to root dentine compared with other sealers.

The percentage of adequate root fillings performed by undergraduate students was only 33%.

Objective:The aim of the present study was to investigate the incidence of dentinal microcracks caused by different preparation techniques.Materials and Methods:120 extracted human mandibular incisor teeth were divided into five experimental groups and one control group (n = 20): Group 1: Hand preparation with balanced force technique up to #25 K-file. Group 2: Preparation with only ProTaper F2 instrument in a reciprocating movement. Group 3: Preparation with Reciproc R25 instrument in a reciprocating movement. Group 4: Preparation with ProTaper instruments up to F2 instrument. Group 5: Preparation with ProTaper Next instruments up to X2 instrument. No procedure was applied to control group. The roots were sectioned horizontally at 3, 6 and 9 mm from the apex and examined. Absence or presence of dentinal microcracks was noted.Results:The Chi-square test was performed to compare the appearance of cracked roots between all groups. There were no significant differences among the groups (P > 0.05).Conclusions:In conclusion, except the hand file and control group, all experimental groups showed microcrack formations.

The group, restored with conventional amalgam, had the weakest resistance to fracture when compared with the bonded restorations. No statistically significant differences were found between the bonded amalgam and composite resin groups.

All the materials used in the present study reinforced the prepared root canals.

INTRODUCTIONRoot-fi lled teeth are more susceptible to fracture than vital teeth. Ironically, these teeth which were already compromised before root canal treatment are further weakened by the process. A few reasons contribute to the vulnerability of root-fi lled teeth, chief of which is root dentin dehydration after the endodontic procedures 1) . Other reasons that predispose root-fi lled teeth to fracture include brittleness of root-fi lled teeth because of loss of tooth structure 2,3) , excessive pressure during fi lling procedures 1,4) , and excessive widening of root canals 5) . After root canal treatment, the standard fi lling material is gutta percha. To obtain a hermetic seal, gutta percha is typically used in conjunction with root canal sealers because gutta percha is incapable of bonding to root canal walls. Root canal sealers not only fi ll the voids between gutta percha points, they also fi ll the voids between gutta percha and root canal walls 6) . Bondable root canal sealers purportedly improve the seal and fracture resistance of endodontically treated roots 7,8) . To date, confl icting results were reported from different research studies. On the one hand, one study 9) found no signifi cant differences in fracture resistance between roots fi lled with a bondable root canal fi lling system, Epiphany, and those fi lled with gutta percha and an epoxy resin-based sealer, AH 26. On the other hand, a study 10) found that the fracture resistance of roots fi lled with gutta percha and AH 26 was superior to that of roots fi lled with the Epiphany system.Recently, a new root canal sealer, iRoot SP (Innovative BioCreamix Inc, Vancouver, Canada), was introduced to the market. According to the manufacturer, iRoot SP is a convenient, pre-mixed, ready-to-use injectable white hydraulic cement paste developed for permanent root canal fi lling and sealing applications. Based on a calcium silicate composition, iRoot SP is an insoluble, radiopaque, and aluminum-free material which requires the presence of water to set and harden.Another recently introduced root canal sealer is MTA Fillapex (Angelus Solucxoes Odontologicas, Londrina, Brazil). Based on an MTA (mineral trioxide aggregate) composition, other ingredients of MTA Fillapex include resins and silica (Table 1). According to the manufacturer, it has high radiopacity, low solubility in contact with tissue fl uids, low expansion during setting, and excellent viscosity for insertion. It does not stain the tooth and promotes deposition of hard tissue at the root apex and perforation sites.The purpose of the study was to compare the fracture resistance of roots fi lled with gutta percha and sealed with one of these three root canal sealers: an epoxy-based root canal sealer AH Plus (Dentsply DeTrey, Konstanz, Germany), a calcium silicate-based root canal sealer iRoot SP, and an MTA-based root canal sealer MTA Fillapex. The null hypothesis was that root canal sealers would not infl uence the fracture resistance of root-fi lled teeth. MATERIALS AND METHODS Root canal p...

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