IADR Abstract Archives
Dentinal Temperature and Deformation in Premolars Restored by Bulk-fill Material
Objectives: The aim of this study was to compare the cuspal strain and dentinal temperature variation in mesio-occlusal-distal (MOD) cavity restored by bulk-fill technique compared to conventional incremental technique.
Methods: 20 extracted premolars were collected and stored in 0.5% thymol at 5 °C. They were stabilized in metal cylinders and divided into two groups (n = 20). Specimens received standardized MOD preparations and were restored according to the following protocols: SDR flow applied in 2mm increments (Group 1); SDR flow applied in bulk fill (Group 2). K-type single-use thermocouples were used to measure temperature profiles. Thermocouples were placed in a standardized hole created within each premolar 1 mm below the cavity floor.
Each specimen was heated at 35°C through the ThermBlock system (FALC), and this temperature was kept constant during the test. An Instron extensometer was used to measure distances between cuspals during the polymerization and post-polymerization processes. The EMS Swiss Master Light lamp 1000 mW/cm2 operating for 20 s was used for the polymerization process. Temperature, cuspal distance and light intensity signals were acquired for one hour using the Signal express software (National Instruments). Data were subjected to statistical analysis ( t-test).
Results: Polymerization of SDR caused an increase of dentinal temperature. No significant differences between Group 1 and Group 2 were recorded. Group 1 (SDR incremental technique) had a higher mean deformation value (p<0.05) than Group 2 ( SDR bulk fill technique). The decrease of cuspals distance was higher in Group 1 compared to Group 2.
Conclusions: Our results demonstrated that bulk fill and conventional incremental technique caused a similar temperature increase at the cavity floor which is not significant to affect pulp tissue. Moreover, we showed that the premolar cuspal deformation is related to the restoration technique used.
Methods: 20 extracted premolars were collected and stored in 0.5% thymol at 5 °C. They were stabilized in metal cylinders and divided into two groups (n = 20). Specimens received standardized MOD preparations and were restored according to the following protocols: SDR flow applied in 2mm increments (Group 1); SDR flow applied in bulk fill (Group 2). K-type single-use thermocouples were used to measure temperature profiles. Thermocouples were placed in a standardized hole created within each premolar 1 mm below the cavity floor.
Each specimen was heated at 35°C through the ThermBlock system (FALC), and this temperature was kept constant during the test. An Instron extensometer was used to measure distances between cuspals during the polymerization and post-polymerization processes. The EMS Swiss Master Light lamp 1000 mW/cm2 operating for 20 s was used for the polymerization process. Temperature, cuspal distance and light intensity signals were acquired for one hour using the Signal express software (National Instruments). Data were subjected to statistical analysis ( t-test).
Results: Polymerization of SDR caused an increase of dentinal temperature. No significant differences between Group 1 and Group 2 were recorded. Group 1 (SDR incremental technique) had a higher mean deformation value (p<0.05) than Group 2 ( SDR bulk fill technique). The decrease of cuspals distance was higher in Group 1 compared to Group 2.
Conclusions: Our results demonstrated that bulk fill and conventional incremental technique caused a similar temperature increase at the cavity floor which is not significant to affect pulp tissue. Moreover, we showed that the premolar cuspal deformation is related to the restoration technique used.