The comparison of AFM surface texture parameters of dental nanohybrid composite polished by two different procedures Tijana Lainović 1, Larisa Blažić 1,2, Marko Vilotić 3, Dragan Kukuruzović 3, Damir Kakaš 3 1 Faculty
of Medicine, School of Dentistry, University of Novi Sad, Novi Sad, Serbia 2 Clinic of Dentistry of Vojvodina, Novi Sad, Serbia 3 Faculty of Technical Sciences, University of Novi Sad, Novi Sad, Serbia
Nanopaprika-profile page url: http://www.nanopaprika.eu/profile/TijanaLainovic Commercially available and the most widely used oral bionanomaterials in dental practice are resin-based composites containing oxide nanoparticles. Dental nanostructured composites are tooth-colored restorative materials for reconstruction of damaged tooth structure. These materials are synthesized in order to improve overall materials properties, including: mechanical, physical, optical and aesthetic characteristics. Nanostructured composites in dentistry can be divided in two groups: nanofilled and nanohybrid composites. Nanofilled materials are filled only with the nanosized inorganic particles, and nanohybrid composites consist of micro-fillers with embedded nanometer-sized particles. The aim of this study was to determine the AFM texture parameters of dental nanohybrid composite and to compare the influence of two different dental polishing protocols on surface roughness of this restorative material. Dental nanohybrid resin-based composite (IPS Empress Direct, Ivoclar Vivadent) was tested in this study (Table 1). The samples were polished by two dental polishing protocols: multi-step and one-step system (Table 2 and Figure 1). Samples were examined by Veeco di CP-II Atomic Force Microscope, in contact mode with CONT20A-CP tips. 1 Hz scan rate and 256 × 256 resolution were used to obtain topography on a 90 × 90 µm scanning area. Average roughness (Ra) and maximum peak-to-valley distance (Rp-v) were analyzed and compared between samples. Material IPS Empress Direct
Manufacturer Classification Ivoclar Vivadent, Liechtenstein
Nanohybrid
Lot no. P74595
Shade Enamel A2
Matrix
Fillers
Dimethacrylate Barium glass filler, Ba-Alfluorosilicate glass Ytterbium trifluoride Prepolymerized fillers Highly dispersed silicon dioxide
Table 1. Details about material tested in the study
AFM image 1. Topography of the sample polished by the multi-step protocol
Filler loading 78,1 in wt%
Figure 1. Polishing setup and directions In the upper left angle – model of a sample and measuring areas Name
Manufacturer
Handpiece speed
Super Snap® (multi- step)
Shofu, inc, Kyoto, 1 minute polishing for each abrasive Japan disk
10 000 rpm*
OneGloss PS® (one-step)
Shofu, inc, Kyoto, 1 minute polishing, Japan dry condition,
5000 rpm*
Table 2. Details about polishing systems tested in the study
It can be seen that surface of the sample polished by multi-step protocol is very smooth, with shallow channels on its surface left from abrasive wear mechanism (AFM image 1). Although it is intended for reduction of clinical chairtime, one-step polishing protocol did not meet the high quality restoration demands of modern dental practice. It caused greater microploughing of the material and dislodging of filler or resin particles (AFM image 2). Multi-step polishing protocol produced significantly smoother surface and lower roughness than the onestep polishing protocol (Charts 1 and 2).
AFM image 2. Topography of the sample polished by the one-step protocol
Ra [nm] 600
Rp-v [nm] 5000
500
4000
400
Usage
3000
300
2000
200
1000
100 0
measuring point 1
2
3 4 5 IPS Empress Direct - one-step IPS Empress Direct - multi-step
6
Chart 1. Comparison of average roughness values between tested samples
0
measuring point
1
2 3 4 5 IPS Empress Direct - one-step IPS Empress Direct - multi-step
6
Chart 2. Comparison of maximum peak-to-valley distance values between tested samples
The adequate dental polishing method needs to be used in order to take advantages of nanostructured materials and to achieve the best clinical outcomes. Surface roughness depends on materials’ composition and processing conditions, and clinicians should use the best therapeutic possibilities. Acknowledgments . Supported by: Project TR 035020 (Larisa Blažić, Tijana Lainović) and Project III-45006 (Damir Kakaš, Dragan Kukuruzović, Marko Vilotić) the Ministry of Education, Science and Technological Development, Republic of Serbia. The authors would like to thank Ivoclar Vivadent product distributers in Serbia, and Mikodental, Šabac – general dealers of Shofu, Japan for Serbia, for the material support.