Cutting efficiency of apical preparation using ultrasonic tips with microprojections: confocal laser scanning microscopy study.
OBJECTIVE
The purpose of this study was to compare the cutting efficiency of a newly developed microprojection tip and a diamond-coated tip under two different engine powers.


METHODS
The apical 3-mm of each root was resected, and root-end preparation was performed with upward and downward pressure using one of the ultrasonic tips, KIS-1D (Obtura Spartan) or JT-5B (B&L Biotech Ltd.). The ultrasonic engine was set to power-1 or -4. Forty teeth were randomly divided into four groups: K1 (KIS-1D / Power-1), J1 (JT-5B / Power-1), K4 (KIS-1D / Power-4), and J4 (JT-5B / Power-4). The total time required for root-end preparation was recorded. All teeth were resected and the apical parts were evaluated for the number and length of cracks using a confocal scanning micrscope. The size of the root-end cavity and the width of the remaining dentin were recorded. The data were statistically analyzed using two-way analysis of variance and a Mann-Whitney test.


RESULTS
There was no significant difference in the time required between the instrument groups, but the power-4 groups showed reduced preparation time for both instrument groups (p < 0.05). The K4 and J4 groups with a power-4 showed a significantly higher crack formation and a longer crack irrespective of the instruments. There was no significant difference in the remaining dentin thickness or any of the parameters after preparation.


CONCLUSIONS
Ultrasonic tips with microprojections would be an option to substitute for the conventional ultrasonic tips with a diamond coating with the same clinical efficiency.
Department of Conservative Dentistry, School of Dentistry, Pusan National University, Dental Research Institute, Yangsan, Korea.
Sang-Won
SW
Kwak
Department of Conservative Dentistry, School of Dentistry, Daejeon Hospital, WonKwang University, Daejeon, Korea.
Young-Mi
YM
Moon
Department of Conservative Dentistry, School of Dentistry, Seoul National University, Dental Research Institute, Seoul, Korea.
Yeon-Jee
YJ
Yoo
Department of Conservative Dentistry, School of Dentistry, Seoul National University, Dental Research Institute, Seoul, Korea.
Seung-Ho
SH
Baek
Department of Conservative Dentistry, School of Dentistry, Seoul National University, Dental Research Institute, Seoul, Korea.
WooCheol
W
Lee
Department of Conservative Dentistry, School of Dentistry, Pusan National University, Dental Research Institute, Yangsan, Korea.
Hyeon-Cheol
HC
Kim
Apical preparation; Apical surgery; Cutting efficiency; Microprojection; Root crack; Ultrasonic tip