Surface changes of metal alloys and high-strength ceramics after ultrasonic scaling and intraoral polishing

Abstract

PURPOSEThis study was to evaluate the effect of repeated ultrasonic scaling and surface polishing with intraoral polishing kits on the surface roughness of three different restorative materials.MATERIALS AND METHODSA total of 15 identical discs were fabricated with three different materials. The ultrasonic scaling was conducted for 20 seconds on the test surfaces. Subsequently, a multi-step polishing with recommended intraoral polishing kit was performed for 30 seconds. The 3D profiler and scanning electron microscopy were used to investigate surface integrity before scaling (pristine), after scaling, and after surface polishing for each material. Non-parametric Friedman and Wilcoxon signed rank sum tests were employed to statistically evaluate surface roughness changes of the pristine, scaled, and polished specimens. The level of significance was set at 0.05.RESULTSSurface roughness values before scaling (pristine), after scaling, and polishing of the metal alloys were 3.02±0.34 µm, 2.44±0.72 µm, and 3.49±0.72 µm, respectively. Surface roughness of lithium disilicate increased from 2.35±1.05 µm (pristine) to 28.54±9.64 µm (scaling), and further increased after polishing (56.66±9.12 µm, P<.05). The zirconia showed the most increase in roughness after scaling (from 1.65±0.42 µm to 101.37±18.75 µm), while its surface roughness decreased after polishing (29.57±18.86 µm, P<.05).CONCLUSIONUltrasonic scaling significantly changed the surface integrities of lithium disilicate and zirconia. Surface polishing with multi-step intraoral kit after repeated scaling was only effective for the zirconia, while it was not for lithium disilicate.

Effect of different polishing systems on surface roughness and color stability of lithium disilicate ceramics

“…Thus, it is important to smoothen the rough surfaces of restorative materials from ultrasonic scaling by using an intraoral polishing system. In fact, intraoral polishing of ceramic restorative material is reported to be difficult due to its high hardness (9,12) . This study evaluated the in-vitro effect of ultrasonic scaling and subsequent intraoral polishing using two different ceramic polishing kits on the surface roughness and color stability of lithium disilicate ceramic.…”

“…The use of an ultrasonic scaler may induce increased roughness of the restoration which may reduce the efficiency of mechanical cleaning processes and enhance the initial adhesion of bacteria and their subsequent colonization to form a biofilm and plaque, (7) gingival irritation, and recurrent caries (8) , causing the adherence of agents responsible for changing the color. Therefore, careful intraoral finishing and polishing of the ceramic surfaces after scaling using the proper technique and materials are recommended (4,9) . For this purpose, a variety of ceramic polishing systems are available in the market.…”

“…Reviewing the literature, there were studies on the effects of scaling on different restorative materials and the surface alterations induced in relation to scaling methods, (9,15) however, few studies have been reported about the surface changes by repeated ultrasonic scaling and subsequent intraoral polishing. Therefore, the aim of this study was to evaluate the surface roughness changes of lithium disilicate ceramics after ultrasonic scaling and polishing with two different intraoral polishing systems.…”

The Effecacy of Different Surface Conditioning on Shear Bond Strength of Orthodontic Bracket Bonded to Lithium Disilcate Crowns; An in Vitro Study

“…Surface conditioning of the ceramic crown categorized into three main methods: mechanical, chemical, or a mix of the two. Chemical conditioning can be achieved by hydrofluoric acid (HFA) to increase bond strength and mechanical one either by Sandblasting with aluminium oxide particles (Kocadereli et al, 2001;Harari et al,2003;Abu Alhaija et al, 2010) or could be done by the ultra-sonic scaling (Yoon et al, 2017) Surface preparation prior to bonding has two goals: to eliminate surface impurities and to expand the substrate's surface area. Marshall et al (2010); By eliminating the glassy matrix, HFA etching produces a porous surface (Lee et al, 2015) Zarif Najafi et al (2019) employed sandblasting as a mechanical retention method.…”

“…Marshall et al (2010); By eliminating the glassy matrix, HFA etching produces a porous surface (Lee et al, 2015) Zarif Najafi et al (2019) employed sandblasting as a mechanical retention method. Since several studies have evaluated changes in surface roughness following ultrasonic scaling (Vigolo & Motterle, 2010;Checketts et al, 2014;Yoon et al, 2017;Nakazawa et al, 2018), ultrasonic scaling will be introduced as a new method of surface conditioning in the current study, hopefully providing a better method of surface conditioning. Consequently, the question arises about the best method(s) of surface conditioning that may be used for bonding orthodontic brackets to lithium disilicate crown.…”