A Comparative Study Of Root Surfaces Using Different Kinds Of Ultrasonic Instruments For Subgingival Scaling

Objective: To assess the efficiency of three kinds of ultrasonic instrumentsfor scaling and root planning, and the roughness of the treated root surfaces, toprovide instructions to choose appropriate ultrasonic instruments in the clinicalapplications.Material and Methods:34extracted teeth which due to advancedperiodontitis were selected for this study. After supragingival scaling, the teethroot surfaces covered with subgingival calculus were marked with an area of5mm×4mm,48root surfaces were selected and randomly assigned to4groups-A, B, C, and D, each group included12root surfaces. All surfaces weretreated with one certain kind of ultrasonic instrument or hand scaler until eachroot surface felt smooth and hard detecting by explorer tip. Group A was treatedwith Odontogain ultrasonic instrument; group B with EMS ultrasonic instrument,group C with Vector system, and hand scaler was used as control in group D.The scaling time of each group was recorded and the root surfaces wereobserved by stereomicroscope and scanning electron microscope.2root surfaces of each group were randomly selected, the scaling area of each root was dividedinto9equal parts to observed by scanning electron microscope under200timesmagnification and took images, analysed the roughness of the treated rootsurfaces.Results:1.Comparation of scaling time: the time taken to clean the selectedareas for Vector system was (164.75±24.19)s, which was significantly longerthan that taken for the Odontogain ultrasonic instrument（42.17±5.18）s, andalso longer than that taken for EMS ultrasonic instrument（55.92±7.56）s andhand scaler（68.50±12.26）s. One-way ANOVA test was used and there was asignificant difference among the four groups（P＜0.05）.2.The roughness of the treated root surfaces: there was a significantdifference among the four groups tested by the nonparametric rank test（H=49.908，P＜0.001）. The roughness were significantly different betweenthe EMS ultrasonic instrument and the Vector system（Z=﹣4.646，P＜0.001）,but there was no difference between the Odontogain ultrasonicinstrument and the EMS ultrasonic instrument（Z=﹣0.143，P＞0.05）.3. Observation under SEM: scratches, pits and smear layer were appeared on theroot surfaces of group A, irregularities and defects of cementum were also seenin this group. There were less scratches, pits and smear layer in group B, itlooked smoother. The smoothest and cleanest treated root surfaces were group C,whose the cementum was observes clearly under high magnification. The root surfaces treated with hand scaler were smooth, but most areas were covered withsmear layer.Conclusions:1.The Odontogain ultrasonic instrument was the mosteffective ultrasonic instrument among the three ultrasonic instruments in scalingand root planning.Vector system was a low effective instrument among the fourinstruments.2. After treatment, the root surface treated by Vector system was smoothest.The root surface treated by Odontogain ultrasonic instrument was roughest.