Gupta S K, Mann N S, Kaur S P, Singh J P

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1 Original Research Gupta S K, Mann N S, Kaur S P, Singh J P Gupta S K, Mann N S, Kaur S P, Singh J P. Bulk Fill Vs Conventional Composites: A Microleakage Study J Periodontal Med Clin Prac 2016;03: Affiliation 1. Dr. Shalu Krishan Gupta (Professor & Head, Department of Conservative Dentistry & Endodontics, National Dental College & Hospital, Derabassi) 2. Dr. Navjot Singh Mann (Reader, Department of Conservative Dentistry & Endodontics, National Dental College & Hospital, Derabassi) 3. Dr. Shubhpreet kaur (PG student, Department of Conservative Dentistry & Endodontics, National Dental College & Hospital, Derabassi) 4. Dr. Jatinderpal Singh (PG student, Department of Conservative Dentistry & Endodontics, National Dental College & Hospital, Derabassi) Abstract: Direct tooth colored restorations are widely used in dentistry due to patients' aesthetic demands for the restoration of dental caries, crown fractures, tooth wear and congenital defects. Hence, composites are widely used nowadays in these cases. Bulk fill restorative materials are newly introduced composites that are placed in increments exceeding 2-mm thickness. These newly developed 'bulkfilled' resins claim to offer single increment placement thickness ranging from 4 to 6 mm instead of the conventional 2 mm value commonly used. Microleakage has been defined as a clinically undetectable movement of bacterial fluids, 6 molecules and ions in microgaps (10 μm) between the cavity wall and the restorative material applied to it. This often leads to failure of restorative materials. However, much studies have not been done on microleakage in bulk fill composites. AIM: To evaluate and compare microleakage in bulk fill and conventional composites in class I cavities. METHOD: 24 freshly extracted human permanent maxillary and mandibular posteriors with no structural deformities were selected. 24 class I cavities were made on the teeth and the depth of the cavity was kept 4 mm. Adper single bond 2 (3M) bonding agent was applied to the etched surface, gently dried and cured. The teeth were then randomly divided into four groups of 6 teeth each. Group I Filtek (3M ESPE) Packable composite, Group II: SonicFill Bulk Fill composite (Kerr/Sybron), Group III: Fill-Up! Bulk Fill composite (Coltene / whaledent), Group IV: SureFil SDR Bulk Fill Flowable Composite (Dentsply). Samples were then covered with two layers of nail varnish, except the resin composite restoration and 1 mm area around it, followed by immersion in 0.6% aqueous rhodamine dye for 48 h. The specimens were rinsed and sectioned at CEJ and then sectioned mesiodistally using diamond disc. Then microleakage was measured using confocal microscopy at 10 X magnification. RESULTS: It was seen that Sonic fill had more microleakage followed by Fill-Up and Filtek while Surefil SDR had least microleakage. CONCLUSION: In Class I restorations, microleakage is observed regardless of the 122

2 composite used and SureFil SDR Bulk Fill shows lesser microleakage when compared with other Bulk fill composites. Key Words - Bulk fill, Conventional Composites, Microleakage, Confocal Microscopy Introduction Composites are tooth colored restorative materials which have been successfully used in dentistry and 1 has widely replaced other materials. A composite restorative material consists of a continuous polymeric or resin matrix into which inorganic fillers are dispersed. They can be described as a dispersed (filler) phase mixed into a continuous (matrix) phase. Restoring large cavities using incremental 2, 3 technique is time consuming. To overcome this, new types of light-curing resin composites have been introduced which claim to be curable to a thickness of 4 mm and are known as 'Bulk fill' 4 composites. Bulk Fill composites possess specific characteristics which includes enhanced flowability to achieve consistent adaptation to the cavity preparation, elasticity and low polymerization shrinkage stress which reduces microleakage, postoperative sensitivity, secondary caries and improved depth of cure thus eliminating 5 the need for layering. Composite materials shrink while polymerizing and this is referred as polymerization shrinkage. It leads to gap formation at the composite and tooth 6 interface. Polymerization contraction of dimethacrylate-based composites ranges from 2-7 6% of volumetric shrinkage. The detrimental effects of polymerization shrinkage stress include bond failure, cuspal flexure, interfacial gap 8 formation and subsequent microleakage. Microleakage is considered to be a major factor influencing the longevity of dental restorations which results in hypersensitivity, recurrent caries 9 and pulpal pathoses. Besides pulpal irritation and secondary caries, microleakage also results in marginal discoloration which is often misdiagnosed as recurrent caries at the margins leading to unnecessary restoration replacement and 10 further tooth structure loss. Microleakage is commonly assessed in vitro using dye penetration to detect bond failure at the enamel resin interface. Confocal laser scanning microscopy (CLSM) is a non-destructive technique. Its advantage is that it clearly indicates leakage limits, eliminating the stain spread caused by specimen sectioning and also avoids polishing 11 artifacts that exaggerate dye penetration. The magnitude of the stress induced during polymerization shrinkage also depends upon other factors, such as the configuration factor (C-factor) 12 of the cavity and the effect of light-curing mode. In this study, the cavities had standard dimensions with standard light curing mode and thus similar C- factor. The aim of this study was to evaluate and compare the microleakage in three different bulkfill composites with increment fill composite. MATERIALS AND METHODS 24 freshly extracted human permanent maxillary and mandibular posteriors with no crack, decay, fracture, abrasion, previous restorations, or structural deformities, which were periodontally compromised were collected and stored in normal saline. Residual tissue tags were removed and specimens were cleaned. 24 class I cavities were made on the teeth and the depth of the cavity was kept 4 mm. Periodontal probe was used to measure the depth of preparation. Each cavity was prepared by number 245 carbide 123

3 bur. After six tooth preparations a new bur was used. Final dimension of the cavity showed 2 mm occlusal width and 4 mm depth. All the prepared cavity surfaces were dried with oil free compressed air, etched with 37% phosphoric acid for 15 s and then rinsed and dried. Adper single bond 2 (3M) bonding agent was applied to the etched surface, gently dried, and cured. The teeth were then randomly divided into four groups of 6 teeth each. Group I Filtek (3M ESPE) Packable composite, Group II: SonicFill Bulk Fill composite (Kerr/Sybron), Group III: Fill-Up! Bulk Fill composite (Coltene / whaledent), Group IV: SureFil SDR Bulk Fill Flowable Composite (Dentsply). The specimens in each group were restored with the corresponding Bulk Fill composite and cured for 20 s according to manufacturer's instructions. The specimens were stored in 100% relative humidity at 37 C for 24 h. They were then covered with two layers of nail varnish, except the resin composite restoration and 1 mm area around it, followed by immersion in 0.6% aqueous 13 rhodamine dye for 48 h. The specimens were rinsed and sectioned at CEJ and then sectioned mesiodistally using diamond disc. The microleakage was measured using confocal microscopy at 10 X magnification (Confocal Fluorescence Imaging Microscope, Leica TCS- SP5, and DM 6000-CFS) in the fluorescent mode. Approximately, six photographs of each specimen were taken to obtain the full perimeter of the restoration. With a digital scale (Snagit digital scale), the width of interface between restoration and tooth surface was calculated and 13 microleakage area was also calculated. RESULTS The following bar chart shows the mean microleakage area of different Bulk fill composites. It was seen that Sonic fill had more microleakage followed by Fill-Up and Filtek while Surefil SDR had least microleakage. There was statistically significant difference between the Sonic fill and Surefil SDR group (P < 0.05) and between the Fill-Up and Surefil SDR group (P < 0.05). 124

4 DISCUSSION Microleakage is defined as the clinically undetectable passage of bacteria, fluids, molecules, or ions between a restorative material and the 14 cavity wall to which it is applied. Microleakage at the tooth-restoration interface is considered a major factor in determining the longevity of dental 15 restorations. It is related with polymerization 16 shrinkage and shrinkage stresses. Minimizing microleakage would improve marginal cavity 17 adaptation. Light intensity is highest at the restoration surface decreasing the pre-gel phase and leading to contraction forces and material 18 shrinkage. The decrease of the polymerization shrinkage and consequent microleakage, can be obtained by an oblique layering technique with increments or 10 cavity designs with a low C-factor. The incremental layering technique and use of lowmodulus intermediate liner material such as flowable composites have been suggested to 19 reduce this shrinkage. As increment layering technique is time consuming as well as cumbersome so bulk fill composites are widely used nowadays. An ideal bulk fill composite would be one that could be placed into a preparation having high C-factor design and still exhibit very little polymerization shrinkage stress, while maintaining a high degree of cure 20 throughout. Currently, bulk fill materials are available in different viscosities, which is low, 21 variable or medium. Dual-cured resin composites have been mainly used as a core material for the reconstruction of non-vital teeth and as dentin substitute in the open 22 sandwich filling technique. Advantages of using dual-cured composites as restorative material are bulk insertion which saves clinical time, the polymerization in deep areas due to chemical curing and the development of low contraction 23 stresses. This study revealed that Sonicfill resin composite had more microleakage while Surefil SDR had least as compared to other bulk fill composites. It could be because Sonicfill combines the attributes of a low viscosity composite and a universal composite and when the composite is activated with sonic energy, the composite changes its 5 consistency until it reaches a higher viscosity. Due to this higher viscosity internal voids are created in the composite which causes microleakage. Surefil SDR is mono-component light-curing composite with minimal internal polymerization stresses because of longer pre-gel phase, which is accomplished by using polymerization modulator that interacts with camphoroquinone to reduce the contraction modulus and increase the number of linear bonds. The immediate result is lower shrinkage stress and preserved 24 polymerization degree responsible for its less microleakage and this reason could be Considering bulk fill placement technique, it has been demonstrated that Surefil SDR showedbetter internal adaptation than conventional composites 25 in high C-factor cavities. Another study (A. Moorthy et. al.) showed similar levels of microleakage of bulk fill ( Surefil SDR X-tra Base) 3 and standard (GrandioSo, VOCO) composites. CONCLUSION Based on the limitations of this study, it may be concluded that in Class I restorations, microleakage is observed regardless of the composite used and SureFil SDR Bulk Fill shows lesser microleakage when compared with other Bulk fill composites. REFERENCES: 1. Lazarchik DA, Hammond BD, Sikes CL, 125

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