MICROLEAKAGE IN CLASS V NANOFILLED COMPOSITE COMPARED WITH TRADITIONAL HYBRID AND FLOWABLE COMPOSITE RESTORATIONS; AN IN VITRO STUDY.
Microleakage in class V restorations (in enamel and cementum), restored with a nanofilled composite was compared to a traditional hybrid resin and flowable composite. Thirty class V cavities were prepared on buccal and lingual surfaces of 15 human premolar teeth, with occlusal and gingival margins at the enamel and cementum/dentin levels, respectively. Specimens were divided into 3 groups with 10 samples of each. Group 1: filled with Cavex composite, Group 2: filled with Premise composite and Group 3: filled with Synergy Flow composite. After being stored in distilled water and finished, the teeth were thermocycled, immersed in a buffered 2% aqueous solution of methylene blue for 2 hours and then embedded in clear resin. They were sectioned and the depth of tracer penetration was measured with periodontal probe and magnifying lens. The results were analyzed using one way ANOV A at the 0.05 level of significance.
All the composite materials showed statistically insignificant differences in occlusal dye penetration (P>0.05) and significant differences in gingival dye penetration (P0.05) in gingival dye penetration values as shown in Table 5.
One of the factors that contribute to marginal micro-leakage in composite restorations is the contrac-tion of the material during polymerization (10, 11). Thermo-cycling may also contribute to the dislodg-ment of the restoration from the cavity walls,10 al-though an in vivo study demonstrated that mastication had a greater influence on the marginal integrity of composite restorations than did thermal stress.12 Poly-merization contraction may cause a break in the adhesion between the tooth and restorative material, resulting in microscopic gaps in the tooth/restoration interface.10,11,13 Thermocycling causes contraction and expansion of the tooth and the restoration, and because they have different coefficients of thermal expansion, the adhesion between them may be broken.10,14
Microleakage is more critical m margins with little or no enamel, which characterizes most of the non-carious class V cavities.15 The cervical margins of such restorations may be at cementum or dentin surfaces. The adhesion between composites and dentin is not as strong as with enamel, therefore the material can be dislodged towards occlusal during polymerization con-traction, causing a bad adaptation of the restoration at the gingival margins.10
In the present study, when comparing the gingival and the occlusal margins of the restorations, the gingival margins of most samples showed the greatest amount of microleakage, which is in agreement with the literatures.10,15,16 When comparing the flowable composite with the hybrid and nanofilled resin, there was no statistically significant difference between them at occlusal Margins Table 3 and this finding is in agreement with Mazer and Russell.17 However, our findings have shown a statistically significant differ-ence between flowable composite with the hybrid and nanofilled resin at gingival margins (Table 4). This finding is not in agreement with Mazer and Russell.17
The incremental technique may have influenced the results as well as the low elastic modulus of the flowable composite and its adaptation to tooth struc-ture that may also have contributed to a smaller polymerization contraction. Differing from the present results, Ferdianakis18 observed a better marginal seal-ing of a flowable composite in comparison with a combination of two traditional hybrid composites.
The present results showed that the cavities re-stored with Synergy Flow composite showed both occlusal and gingival leakage higher than that of Cavex hybrid composite and lower (except for occlusal higher) than that of premise nanofilled composite. (Figure 1) The difference between Cavex and Premise could be due to the amount of filler loading by volume (Table 1) as increasing the amount of filler loading above a critical point results in increasing the stiffness of the material and reducing its ability to flow during poly-merization.
The study has concluded the following;
All the composites tested exhibited little or no occlusal leakage.
None of the composites completely sealed the tooth/restoration interface at the gingival mar-gins.
The nanofilled composite exhibited the highest gingival leakage.
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1 ALI ABDULWAHAB AL-RAZOOKI, BDS, MSc, PhD
2 MOHAMMAD MUSTAHSEN UR REHMAN, BDS, PhD
2 Associate Professor /Deputy Dean, College of Dentistry, Ajman University of Science & Technology Network, Fujairah Campus, UAE
Correspondence: 1Dr Ali Abdulwahab Al- Razooki, Assistant Professor, College of Dentistry, Ajman University of Science & Technology Network, PO Box 2202, Fujairah Campus UAE: 00971 50 2913309 Fax; 00971 9 2227644
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|Publication:||Pakistan Oral and Dental Journal|
|Date:||Jun 30, 2010|
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