RESUMEN
The purpose of this study was to investigate the effect of blood contact and tooth mobility on volumetric changes of calcium silicate-based root-end filling materials using a micro-CT. Three calcium silicate-based materials (ProRoot MTA, Biodentine, and RetroMTA) were used in this study. Seventy-two extracted human single-rooted premolars were obturated with gutta percha. Root-end resection and root-end preparation were performed. After root-end filling with tested materials, the tooth specimens were immersed in saline or blood for 5 days in a 37 ℃ incubator (n=8). The tooth specimens were mounted in a chewing simulator to simulate tooth mobility with a force of 30 N and 20,000 cycles. Micro-CT scans were performed immediately after root-end filling and after exposure to storage media or simulation of tooth mobility. The volume loss (%) was obtained from difference in the percentage of defects of materials between first and second micro-CT scans. Apical volume loss (%; volume loss from resected surface to 1 mm from the surface) was calculated for tooth mobility simulating groups. Biodentine showed larger total volume loss than ProRoot MTA and RetroMTA in saline and blood. ProRoot MTA had smaller total volume loss in blood than in saline. Under the condition simulating tooth mobility, total volume loss was similar among materials, and apical volume loss of Biodentine was larger than that of RetroMTA. In conclusion, ProRoot MTA or Retro MTA is recommended in clinical situation of intentional replantation where tooth mobility or direct contact with blood may occur.
RESUMEN
The purpose of this study was to measure the polymerization shrinkage and hygroscopic expansion of resin-based temporary filling materials and to evaluate microleakage at the interface between the materials and cavity wall. Five resin-based temporary filing materials were investigated: Fermit (Vivadent), Quicks (Dentkist), Provifil (Promedica), Spacer (Vericom), Clip (Voco). Caviton (GC) was also included for comparison. Polymerization shrinkage of five resin-based temporary filling materials was measured using the bonded disc method. For the measurement of hygroscopic expansion, the discs of six cured temporary filling materials were immersed in saline and a LVDT displacement sensor was used to measure the expansion for 7 days. For estimating of microleakage, Class I cavities were prepared on 120 extracted human molars and randomly assigned to 6 groups of 20 each. The cavities in each group were filled with six temporary filling materials. All specimens were submitted to 1000 thermo-cycles, with temperature varying from 5degrees C/55degrees C. Microleakage was determined using a dye penetration test. The results were as follows: 1. Fermit had significantly less polymerization shrinkage than the other resin-based temporary filling materials. Fermit (0.22 %) < Spacer (0.38 %) < Quicks (0.64 %), Provifil (0.67 %), Clip (0.67 %) 2. Resin-based temporary filling materials showed 0.43 - 1.1 % expansion in 7 days. 3. Fermit showed the greatest leakage, while Quicks exhibited the least leakage. 4. There are no correlation between polymerization shrinkage or hygroscopic expansion and microleakage of resin-based temporary filling materials.