Effect of Three Different Polishing Techniques on Surface Roughness and Bacterial Adhesion of Two Composite Resin

Research Article

Austin J Dent. 2018; 5(4): 1110.

Effect of Three Different Polishing Techniques on Surface Roughness and Bacterial Adhesion of Two Composite Resin

Daneshkazemi AR¹, Davari AR¹, Shirkhoda M², Zandi H³ and Behniafar B4*

¹Department of Operative Dentistry, Social Determinant of Oral Health Research Center, Shahid Sadoughi University of Medical Sciences, Iran

²Tehran University of Medical Sciences, Iran

³Department of Microbiology, Faculty of Medicine, Shahid Sadoughi University of Medical Sciences, Iran

4Department of Restorative Dentistry, Faculty of Dentistry, Tehran University of Medical Sciences, Iran

*Corresponding author: Behniafar B, Department of Restorative Dentistry, Faculty of Dentistry, Tehran University of Medical Sciences, North Kargar, Tehran, Iran

Received: January 28, 2018; Accepted: February 21, 2018; Published: March 16, 2018


Background and Aim: Resin composites are widely used in restorations. The adhesion of bacterial plaque to restorations depends on the surface properties and the composition of materials. As the Streptococcus Mutans has a major role in primary and secondary caries, the purpose of this in-vitro study was to examine the effect of different surface treating techniques on surface roughness and the amount of bacterial plaque adhesion on two types of resin composites.

Materials and Methods: 120 samples (3×6 mm) of each Filtek Z250xt (3MESPE) and Filtek P90 (3MESPE) were produced and randomly divided into 4 surface treatment techniques: 1) composite resin surface in contact with mylar strip with no finishing or polishing performed. 2) Soflex aluminium oxide disc (3MESPE) 3) silicon-carbide rubber points (Politip P and F: Ivoclar Vivadent) 4) felt wheel with diamond paste (Diamond Excel: FGM). Surface roughness was measured with a profilometer. Test specimens were subjected to S.Mutans (PTCC 1683) biofilm development. The S.Mutans biofilm was calculated and recorded by the mean log of CFU/ml. The data was statistically analyzed by One-way and Two-way ANOVA analysis of variance and the Bonferroni test (P<0.05).

Results: The mylar strips showed the lowest amount of surface roughness in the two type of resin composites. While in the P90 composite, using the mylar strips had the highest amount of bacterial adhesion. The composite type and the surface treatment methods had significantly influenced the surface roughness and the bacterial adhesion.

Conclusion: Using different polishing techniques after polymerization of P90 in contact with mylar strips significantly reduces the bacterial plaque adhesion.

Keywords: Composite, Surface roughness, Bacterial plaque, Surface treatment


Resin composites are extensively used in anterior and posterior restorations [1]. The composite resins have been developed to minimize the critical drawbacks of the polymer-based materials such as polymerization contraction, fatigue, occlusal wear, organic matrix degradation, surface roughness, insufficient contour and fractures [2,3]. Surface treatments such as finishing and polishing have an important role in clinical performance of these resin-based materials [4]. The finishing procedure is required to refine the anatomy of the restoration, whereas the polishing procedure aims at reducing the surface roughness produced by finishing appliances [4]. Composite’s surface roughness also depends on the chemical composition and mechanical properties of these restorative materials [5-7].

In resin composites composition, the organic matrix and the inorganic fillers have different hardness values and in consequence present contrasting wear properties due to occlusal loads. The organic component wears rapidly and exposes the inorganic fillers, which are dislodged by attrition. Therefore, higher surface roughness is achieved due to larger particle size of the inorganic fillers [8-12]. Furthermore, surface roughness value is an important factor in microbial plaque accumulation on composite surface in clinical situations [13-15]. In the point of fact, the type, size and amount of inorganic fillers have effect on mechanical properties and polishing of composite resins [16]. Therefore resin composites with wide distribution of nano-sized fillers, have been produced because of improved mechanical and esthetic properties [7,11]. Streptococcus Mutans is the most prevalent bacteria in secondary caries; therefore well-polished composite surfaces reveal a noticeably reduced amount of bacterial adherence and colonization [2].

Weinmann, et al. claimed that silorane based restorations have lower potential to absorb the dyes of the daily nutrition due to their silorane subcomponent, which has a hydrophobic property in the material. Therefore it can be supposed that silorane-based composites can have less potential for bacterial adhesion [17]. However there is no distinct information about their potential of bacterial adhesion, which can have a considerable influence on their clinical longevity. Aluminum-oxide disks can be used for finishing and polishing of composite resins, however because of their shape, they are not used in occlusal surfaces and are mostly applied in proximal surfaces [6,8,11,18-21]. Multi-fluted carbide burs, diamond burs, brushes , abrasive pastes and silicon carbide burs are commonly used in order to have well-polished occlusal posterior surfaces [21,23]. A perfect polished composite surface illustrates extreme esthetics and significant decrease in initial bacterial adherence and colonization. Furthermore, polishing of a composite restoration will decrease periodontal disease, marginal staining and secondary caries which originate from S. Mutans and S.Sobrinus [8,11,12,24-27]. Generally, the most reason for replacement of composite restorations is secondary caries which has effect on the durability of the restorations. The formation of biofilm and bacterial colonization on composite restorations may result in secondary caries [28-31]. Based on the facts described, the aim of this study was to evaluate the adherence of S.Mutans on the surface of Silorane-based (P90) and nanohybrid (Z250xt) composites which have been polished with aluminum-oxide discs, rubber points and polishing paste (and a control group with mylar strips). The correlation between bacterial adherence value and surface roughness of each prepared composite sample was estimated.

Methods and Materials

Composition information of two type of composites used in this study are presented in Table 1. 120 sample of each composite was prepared within a custom cylindrical-shaped steel mold (6 mm in diameter and 3 mm in height). The mold was filled with 1.5 mm increments of composite resin and the final increment was carved with mylar matrix strip. The top surface was cured for 40 seconds with a light curing device (Demi: Kerr-USA with 800 mw/cm2 intensity). Samples were removed out from the mold and the excess composite was cut by surgical blade. Samples were immersed in black vials occupied with 37 °C distilled water for 24 hours [32].