RESUMEN
Purpose@#This study aimed to evaluate the effect of repeated use of an implant handpiece under an implant placement torque (35 Ncm) and overloading torque condition (50 Ncm) on an output torque. @*Materials and Methods@#Two types of implant handpiece systems (Surgicpro/X-DSG20L [NSK, Kanuma, Japan] and SIP20/CRB46LN [SAESHIN, Daegu, South Korea]) were used. The output torque was measured using a digital torque gauge. The height and angle (x, y, and z axes) of the digital torque gauge and implant handpiece were adjusted through a jig for passive connection. The experiment was conducted under the setting torque value of 35 Ncm (implant placement torque) and 50 Ncm (overloading torque condition) and 30 times per set; a total of 5 sets were performed (N = 150).For statistical analysis, the difference between the groups was analyzed using the Mann–Whitney U test and the Friedman test was used to confirm the change in output torque (α=.05). @*Results@#NSK and SAESHIN implant handpieces showed significant differences in output torque results at the setting torques of 35 Ncm and 50 Ncm (P <.001). The type of implant handpiece and repeated use influenced the output torque (P <.001). @*Conclusion@#. There may be a difference between the setting torque and actual output torque due to repeated use, and the implant handpiece should be managed and repaired during long-term use. In addition, for successful implant results in dental clinics, the output torque of the implant handpiece system should be checked before implant placement.
RESUMEN
Purpose@#The primary objective of this study was to evaluate the change in the temperature of the adhesive resin in polycrystalline ceramic brackets irradiated using a diode laser at different irradiation energy levels and times. @*Materials and Methods@#For the measurement of the temperature of the adhesive resin, it was applied at the base of the ceramic bracket, a thermocouple was placed at the center of the base surface, the bracket was placed on prepared resin specimens for light curing, and a laser was irradiated to the center of the bracket slot at 5, 7, and 10 W. For the measurement of the temperatures of the enamel under the bracket and pulp cavity, extracted premolar was fixed to a prepared mold and the ceramic bracket was bonded to the buccal surface of the premolar. The Kruskal–Wallis H test and Friedman test were used for statistical analysis.Result: At 5 W, the temperature of the adhesive resin did not reach the resin softening temperature of 200°C within 30 seconds. At 7 W, it reached 200°C when the ceramic bracket was irradiated continuously for 28 seconds. At 10 W, it reached 200°C when the ceramic bracket was irradiated continuously for 15 seconds. During laser irradiation, the temperature of the enamel under the bracket increased by over 5°C within 15 seconds. @*Conclusion@#The use of diode laser irradiation for bracket debonding should be carefully considered because the pulp cavity temperature increases by over 5°C within the irradiation time for resin thermal softening.
RESUMEN
Purpose@#This study aimed to evaluate the effect of repeated use of an implant handpiece under an implant placement torque (35 Ncm) and overloading torque condition (50 Ncm) on an output torque. @*Materials and Methods@#Two types of implant handpiece systems (Surgicpro/X-DSG20L [NSK, Kanuma, Japan] and SIP20/CRB46LN [SAESHIN, Daegu, South Korea]) were used. The output torque was measured using a digital torque gauge. The height and angle (x, y, and z axes) of the digital torque gauge and implant handpiece were adjusted through a jig for passive connection. The experiment was conducted under the setting torque value of 35 Ncm (implant placement torque) and 50 Ncm (overloading torque condition) and 30 times per set; a total of 5 sets were performed (N = 150).For statistical analysis, the difference between the groups was analyzed using the Mann–Whitney U test and the Friedman test was used to confirm the change in output torque (α=.05). @*Results@#NSK and SAESHIN implant handpieces showed significant differences in output torque results at the setting torques of 35 Ncm and 50 Ncm (P <.001). The type of implant handpiece and repeated use influenced the output torque (P <.001). @*Conclusion@#. There may be a difference between the setting torque and actual output torque due to repeated use, and the implant handpiece should be managed and repaired during long-term use. In addition, for successful implant results in dental clinics, the output torque of the implant handpiece system should be checked before implant placement.
RESUMEN
Purpose@#The purpose of this study was to assess the marginal and internal fit of interim crowns fabricated by two different manu-facturing method (subtractive manufacturing technology and additive manufacturing technology). @*Materials and Methods@#Forty study models were fabricated with plasters by making an impression of a master model of the maxillary right first molar for ceramic crown. On each study model, interim crowns (n = 40) were fabricated using three types of 3D printers (Meg-printer 2; Megagen, Zenith U; Dentis, and Zenith D; Dentis) and one type milling machine (imes-icore 450i; imes-icore GmbH). The internal of the interim crowns were filled with silicon and fitted to the study model. Internal scan data was obtained using an intraoral scanner. The fit of in-terim crowns were evaluated in the margin, absolute margin, axial, cusp, and occlusal area by using the superimposition of 3D scan data (Geomagic control X; 3D Systems). The Kruskal-wallis test, Mann-Whitney U test and Bonferroni correction method were used to compare the results among groups (α = 0.05). @*Results@#There was no significant difference in the absolute marginal discrepancy of the temporary crown manufactured by three 3D printers and one milling machine (P = 0.812). There was a significant difference between the milling machine and the 3D printer in the axial and occlusal area (P < 0.001). The temporary crown with the milling machine showed smaller axial gap and higher occlusal gap than 3D printer. @*Conclusion@#Since the marginal fit of the temporary crown produced by three types of 3D printers were all with in clinically acceptable range (< 120 µm), it can be sufficiently used for the fab-rication of the temporary crown.
RESUMEN
Purpose@#The purpose of this study was to assess the marginal and internal fit of interim crowns fabricated by two different manu-facturing method (subtractive manufacturing technology and additive manufacturing technology). @*Materials and Methods@#Forty study models were fabricated with plasters by making an impression of a master model of the maxillary right first molar for ceramic crown. On each study model, interim crowns (n = 40) were fabricated using three types of 3D printers (Meg-printer 2; Megagen, Zenith U; Dentis, and Zenith D; Dentis) and one type milling machine (imes-icore 450i; imes-icore GmbH). The internal of the interim crowns were filled with silicon and fitted to the study model. Internal scan data was obtained using an intraoral scanner. The fit of in-terim crowns were evaluated in the margin, absolute margin, axial, cusp, and occlusal area by using the superimposition of 3D scan data (Geomagic control X; 3D Systems). The Kruskal-wallis test, Mann-Whitney U test and Bonferroni correction method were used to compare the results among groups (α = 0.05). @*Results@#There was no significant difference in the absolute marginal discrepancy of the temporary crown manufactured by three 3D printers and one milling machine (P = 0.812). There was a significant difference between the milling machine and the 3D printer in the axial and occlusal area (P < 0.001). The temporary crown with the milling machine showed smaller axial gap and higher occlusal gap than 3D printer. @*Conclusion@#Since the marginal fit of the temporary crown produced by three types of 3D printers were all with in clinically acceptable range (< 120 µm), it can be sufficiently used for the fab-rication of the temporary crown.