The aim of this study was to compare solubility, microhardness, radiopacity, and setting time of Biodentine with ProRoot MTA. Solubility in distilled water, radioopacity, and setting time were evaluated in accordance with International Standard ISO 6876:2001. In addition, the solubility in Phosphate Buffered Saline (PBS) buffer was determined. For microhardness-testing, ten samples of each cement were produced. All samples were loaded with a diamond indenter point with a weight of 100 g for 30s. All data were analysed using the Student-t-test. Both materials fulfilled the requirements of the International Standard ISO 6876:2001 and showed a solubility of <3% after 24 h. At all exposure times Biodentine was significantly more soluble than ProRoot MTA (p < 0.0001). After immersion in PBS-buffer a precipitation of hydroxyapatite was visible. The Vickers microhardness for Biodentine was significantly higher (62.35 ± 11.55HV) compared with ProRoot MTA (26.93 ± 4.66HV) (p < 0.0001). ProRoot MTA was significantly more radiopaque (6.40 ± 0.06 mm Al) than Biodentine (1.50 ± 0.10 mm Al) (p < 0.0001). The setting time for Biodentine (85.66 ± 6.03 min) was significantly lower than for ProRoot MTA (228.33 ± 2.88 min) (p < 0.0001). Biodentine and ProRoot MTA displayed different material properties. The solubility of both cements was in accordance with the International Standard ISO 6876:2001, whereas ProRoot MTA showed a significantly lower solubility. With regard to microhardness, Biodentine may be used to replace dentine. The radioopacity of Biodentine did not fulfil the requirements laid down in the International Standard ISO 6876:2001. The setting time for ProRoot MTA is significantly higher. Both materials can be used in different indications where specific material properties may be favourable. Hence, the here tested material properties are of clinical relevance.

The aim of this study was to compare the effect of hand instruments and rotary nickel titanium Flex-Master files used by eight experienced dentists in private practice on the extent of straightening of curved root canals. In patients, 110 canals were prepared by FlexMaster instruments, and 84 canals were enlarged using hand instruments. After instrumentation, all canals were obturated. Preoperative and postoperative radiographs were taken of each tooth using customized bite blocks. Straightening of the canal curvatures was determined with a computer image analysis program. Preparation time and size of the master apical file were also recorded. The use of FlexMaster instruments resulted in significantly less straightening and a shorter preparation time (p < 0.0001) compared with hand instrumentation. Master apical file sizes were significantly greater for FlexMaster than for hand instruments (p < 0.01). This clinical study indicates that FlexMaster instruments prepared curved canals rapidly and with only minimal straightening.