Evaluation of the Surface Roughness for Three Different Types of Composite Resin Materials Using ( Sof – Lex ) Finishing and Polishing Systems : A Comparative Study

Aim: To evaluate the surface roughness of three different types of light activated composite resin using (Sof-Lex) – polishing system, a profilometer study. Materials and Methods: A total of 30 resin composite disks were prepared from three different types of composite resin include 3 – groups. Group I: 10 specimens were prepared from light activated nano hybride (Tetric n – Ceram, Ivoclar – Vivadent – Liechtenstein). Group II: 10 specimens were prepared from light activated microhybride composite resin (Arabesk – Voco, Germany). Group III: 10 specimens were prepared from light activated polyglas composite resin (Solitaire – 2, Heraeus, Kulzer, Germany). The resin blocks finished and polished using (Sof – Lex) polishing system. The specimens were analyzed for surface roughness using “Profilometer”. Results: Tetric n – Ceram composite resin showed the lowest roughness average (0.112 μm) followed by Arabesk composite (0.150 μm), Solitaire – 2 composite resin showed the highest roughness average (0.341 μm). Conclusions: Tetric n– Ceram (nano-hybride) was the best polished composite resin, showed the least roughness average.


INTRODUCTION
Composite is a heterogeneous material that is composed of three major components (resin matrix, filler particles and saline coupling agent). (1)ince 1960 dental composite introduced in dentistry.They have undergone a lot of changes in order to become a restorative material with acceptable aesthetic properties. (2)cent advancement in direct dental restorative materials is the incorporation of the nanotechnology which is understanding and control of matter at dimension of roughly 1 -100 nm. (2)dequate finishing and polishing of resin composites is a prerequisite for high quality, esthetic and enhanced longevity of the resinbased restorations.Finishing refers to as the contouring of the cured Evaluation of the Surface Roughness for Three Different Types of Composite Resin Materials Using (Sof-Lex) Finishing and Polishing Systems: A Comparative Study restoration where as polishing reduce the roughness produced by finishing instrument. (3)olishing is the process carried out after the finishing procedure to remove minute scratches from the surface of a restoration and to obtain a smooth, light reflective luster surface. (4) variety of instruments are commonly used for finishing and polishing toothcolored restorative materials including: carbide finishing burs, 25 -50 µm diamond finishing burs, abrasive impregnated rubber cups and points, aluminum oxide coated abrasive discs, abrasive strips and polishing pastes. (5)eraeus system (HER).Shofe system (SHO), (Sof -Lex) system, POGO polisher and others are different systems used for polishing finished composite resin. (3)of -Lex system is a multistep abrasive disks containing aluminum oxide abrasive, used for polishing composites, is the polishing system which is preferable, because it gives better results. (3,5)roper finishing and polishing for both anterior and posterior composite restoration are important step that enhance both esthetics and longevity of the restored teeth, surface roughness associated with improper finishing and polishing can result in excess surface staining, increased wear rates and plaque accumulation which compromised the clinical performance of the restoration. (6,7)he aim of this study to evaluate the surface roughness for three different types of light activated composite resin using (Sof-Lex)polishing system.(A profilometer study).

MATERIALS AND METHODS
The study was carried out in the Department of Conservative Dentistry, College of Dentistry, University of Mosul and Department of Mechanical Engineering, University of Salahaddin.
A total of 30 specimens (disk) (10mm) in diameter and (3 mm) in height were prepared from three different types of light activated composite resin, as shown in Table (1) and Figure (1), include 3groups.Group I: 10 specimens were prepared from light activated Nano hybride (Tetric n -Ceram, Ivoclar -Vivadent -Liechtenstein).Group II: 10 specimens were prepared from light activated microhybride composite resin (Arabesk -Voco, Germany).Group III: 10 specimens were prepared from light activated polyglas composite resin (Solitaire -2, Heraeus, Kulzer, Germany).The specimens of light activated composite resin were prepared using a Teflon mold.The mold had a central hole measuring (10 mm) in diameter and (3 mm) in height.The mold was inserted in a glass slide and filled with a composite resin using an incremental technique layer by layer with a plastic instrument, covered with Mylar strip and glass slide to produce a smooth surface and facilitate light curing.The specimens were cured with visible light curing ,"activation" was done with Blue-luxcer TM -curing light (Model M855-Halogen lamp, Monitex Taiwan 08H0151) for 40 seconds, from top of the specimen .The mold through the glass slide was exposed to light from uper,lower,right,left cover stript sides.With light intensity of the curing unit was standardized to at least 500 nm (output) double the recommended time to ensure complete polymerization of the specimens which storage in distilled water. (3,5)he resin blocks were finished to a uniform surface using carbide bur (Komet, UK) at medium speed for 10 seconds under water coolant for each of the surfaces to create base line finishing.
Finishing and Polishing procedure include using (Sof -Lex) polishing system which include using multistep abrasive disc (Sof -Lex) TM aluminum oxide disk (Soflex, 3M ESPE, Dental products, St. Paul, USA) used for polishing composite.
As we mentioned a number of finishing and polishing devices are available (Soflex, Heraeus, Shofer, PoGo system). (3,5)Soflex is a better finishingpolishing system then others its has become a standard frequently used in research trial because of a smooth surface commonly achieved without destroying the composite resin surface. (3,5)Thirty samples were polished with aluminum oxide abrasive disks in the kit were attached by a metal hub to the autoclavable metal mandrel as shown in Figure (2).The coarse grit disk (brown in colour) was used for gross reduction at decrease speed of low speed motor hand piece, the medium grit disk (yellow in colour) was used for gross contouring at a decrease speed for 15 -20 second.The fine grit disc (green in colour) followed by superfine grit disc (blue in colour) was used to finish at increase speed of low speed motor hand piece for 15 -20 seconds. (3,5)fter the samples were finishedpolished, the samples were analyzed for surface roughness using a two dimensional surface profilmeter (Taylor -Hobson "Talysurf -10" made in UK) as shown in Figure (3).The roughness average (Ra) of the specimens was defined as the arithmetic average height of roughness component irregularities from the mean line measured with the sampling length. (3,5)rofilmeter readings were made at the centre, right and left side of each specimen and the numerical average was determined for each group, it provided a quantative recording of the surface irregularities (3,5) as shown in Figure (4).The profilmeter produce a tracing using a digital and analogue hardware and software and calculates the average surface roughness (Ra) value for the resultant tracing. (3,5)Data were collected ANOVA and Duncan multiple range test was used for statistical analysis.

RESULTS
The results shown in Table (2).ANO-VA and Duncan Multiple Range Test was applied to determine the significant differences in the surface roughness among different groups.P-value of 0.05 or less was considered as statistically significance.Profilometer provides a digital readout of the average surface roughness (Ra) in microns.The average roughness value represents the arithmetic mean of the height of all surface irregularities over a predetermined linear segment of each specimen.
Statistical analyses were performed for data using one way ANOVA and Duncan multiple range tests.The surface roughness average showed that there is statistically significant difference (p< 0.05) among three different types of light activated composite resin.

DISCUSSION
Composite restoration was finished and polished in order to establish a functional occlusal relationship and contour physiologically in harmony with supporting tissues, proper contour and high gloss give the restoration the appearance of natural tooth structure. (3,7)esin -based composites resins can't be finished to an absolutely smooth surface, as it is essential requiste for a successful restoration.The finishing and polishing procedures directly influence the longevity of the restoration and its environment. (3,7)he final polish obtained on a composite restoration would be determined by two factors: composition of the composite with relation to the matrix, size of filler particles and the type of polishing system used.The degree of polymerization of the matrix, the size, composition and volume of the filler particles affect the surface finish obtained on the composites which are the resin matrix and filler particles don't abrade to the same degree. (8)he larger the filler particles, the rougher the surface would be after polishing. (3,9)12) Several investigations have shown that removal of the polymerrich outer most resin layer is essential to achieving a stain resistant, more esthetically stable surface. (9,13,14)n this study, there is significant difference in the surface roughness after using Sof -Lex polishing systems among 3 different types of light activated composite resin at level of significance (p< 0.05).(17) Also in this study, Arabesk (microhybride composite) showed roughness average (0.150) higher than that of Tetricn Ceram , this could be in-Tetric-n ceram the particle size of the inorganic filler incomposite resin are so small (nano-hybride).Arabesk can be finished and polished to a smooth surface, and it is distinguished by its high level of colour stability. (11,12,18)oledano et al (19) evaluated surface roughness for resin composites after using two polishing methods, they concluded that microfill and microhybride composites can be finished to a very smooth surfaces with a surface roughness average (Ra) varying from 0.12 to 0.25 µm due to their small filler particle size and arrangement.The size of microfill composite filler is 0.04 µm and a microhybride contains particles that range between 0.01 and 2.0 µm, therefore, they can finished to a smoother surface than that of packable (Solitaire -2) composites evaluated in their study. (19)he highest roughness average were recorded for Solitaire -2 composite (0.341) in comparison with others (Tetric n -Ceram, Arabesk), as we mentioned above that the larger the filler particles the rougher the surface would be after polishing. (3,9,20)dequate finishing and polishing of composite resin is a prerequisite for high quality, esthetic and enhanced longevity of the resin based restoration. (3)urface roughness associated with improper finishing and polishing can resulted in excess surface staining increase wear rates and plaque accumulation which compromised the clinical performance of the restoration. (6,7)

CONCLUSIONS
The Tetric n-ceram that has particles size of inorganic filler in composite resin are so small.They give the best polished surface and a lowest roughness average.In comparison with others (Arabesk, Solitare, 2).(Sof-lex) TM polishing system give better results, a smooth surface commonly achieved without destroying the composite resin surface.

Figure ( 1 )
Figure (1): Light activated composite materials used in this study

Table ( 1
): Composition of the three different types of light activated composite resin.

Table ( 2
): Roughness average (Ra) after using (Sof -Lex) polishimg system for three different types of composite resin.

Table ( 3
): ANOVA and Duncan's multiple range tests of the roughness average (Ra) for the 3different composite groups.
Different letters mean significant difference at p≤ 0.05