Master of Science (M.S.) in Dentistry
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College of Dental Medicine
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Nova Southeastern University
Salam Hetou. 2018. Comparison of cutting efficiency of different rotary instruments, on two different ceramic materials using electric and air-turbine dental hand-pieces. Master's thesis. Nova Southeastern University. Retrieved from NSUWorks, College of Dental Medicine. (125)
Objective. This study compared the cutting efficiency of different diamond rotary cutting instruments on twoceramic materials when used with an electric handpiece versus an air-turbine handpiece. The amount of surface roughness exhibited by an electric hand-piece was also evaluated in comparison with an air-turbine hand-piece, when used to cut through ceramic restorative materials in a simulated crown removal procedure. Materials and Methods.One-hundred and sixty ceramic specimens were fabricated from lithium disilicate (IPS e.max Press, Ivoclar Vivadent, Amherst, NY) and zirconium oxide (ZirCAD, Ivoclar Vivadent, Amherst, NY) with standardized dimensions (5mm x 2mm x 20mm). Samples were divided into eight groups according to diamond burs types (coarse and fine) and type of handpiece used. There were twenty samples in each group. A standardized cutting system, comprised of an air turbine handpiece (Gentleforce LUX 6000B, Kavo America, Lake Zurich, IL) or an electric handpiece (MASTERmatic LUX M25 L High Speed, Kavo America, Lake Zurich, IL), mounted in a brass cylinder attached to an L-shaped, clear acrylic resin vertical block by a frictionless bearing, was used for sectioning. A cutting force of 0.90 N (102.1 g) was applied to the handpiece at the diamond and ceramic specimen interface. A total of eighty cuts were performed in each group. Four cuts were made in each substrate with each bur type, using a different bur for each block with each cut being timed to 0.1 second to measure cutting efficiency. Cutting efficiency was determined as mm/min. These data were analyzed using a one-way analysis ofvariance (ANOVA) test with significance set at p < 0.05. A Šidák test was used to compare groups. Results. The electrichandpiece cut significantly faster (p < 0.05) than the air turbine handpiece on both the lithium disilicate and zirconia blocks. Fine diamond burs cut through lithium disilicate specimens significantly slower than coarse diamond burs (p < 0.05) when using the air turbine handpiece. Fine diamond burs cut through zirconium oxide faster when compared to coarse diamond burs, but this was not statistically significant (p > 0.05). The electric handpiece exhibited a significantly faster rate when cutting through lithium disilicate using fine diamond burs (p < 0.05). In regards to surface roughness, zirconia blocks showed smoother surfaces when cut using the fine diamond bur and the air turbine handpiece. Conclusions. Within the limitations of this study, it is recommended to use an electric handpiece using coarse diamond burs when cutting through lithium disilicate and electric handpiece using fine diamond burs when cutting through zirconium oxide.
Ceramics; Dental diamond burs, Dental handpieces, Lithium disilicate, Zirconia
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