The effect of low shrinkage dental composite on the fracture strength of weakened premolar teeth (An in vitro study)

Khafaji,; H. Al, Ali; I. Suhail, Rasshaa

	The effect of low shrinkage dental composite on the fracture strength of weakened premolar teeth (An in vitro study)
Journal of baghdad college of dentistry
Article 1, Volume 23, Issue 3, 2011, Pages 30-36
Authors
; Ali H. Al; Rasshaa I. Suhail
Abstract
ABSTRACTBackground: The aim of the study was to evaluate and compare the fracture resistance of weakened maxillarypremolar teeth with MOD preparations restored with low shrinkage new Silorane based composite (Filtek p90) incomparison to low shrinkage methacrylate based composite (1-packable Filtek p60,2- nanohybrid Tetric Evoceram ).Materials and Metods: Fifty human adult maxillary premolar teeth recently extracted for orthodontic purpose wereselected. These teeth received MOD cavity preparations with no proximal boxes. The teeth were then randomlydivided in to five groups (n=10), according to the material used for restoration: Group A (Teeth were not prepared ),Group B (Teeth, with MOD cavity preparation were not restored.) Group C (Teeth, with MOD cavity preparation wererestored with Filtek p60 packable composite), Group D (Teeth, with MOD cavity preparation were restored with TetricEvoceram nanohybrid composite) Group E (Teeth, with MOD cavity preparation were restored with Filtek p90 siloranebased composite). These specimens were then stored in an incubator at 37Ċ for one week, at 100% humidity indeionized water before test. Cuspal fracture resistance was determined using compressive testing machine.Thefracture specimens in group C,D and E were stained with 1%methylene- blue dye for 24 hours then examined bystereo microscope ×40 to evaluated the mod of failure, the data were staistically analyzed using Analysis of variancetest (ANOVA), LSD test and student t-test .Results: The results showed that there’s a high significant improvement of the fracture resistant of restored teeth usingposterior composite as compared to the unrestored ones, but; ther’s no difference of the type of the posteriorcomposite material used on the fracture resistance of the weakened teeth, while the sound teeth remained thestrongest teeth compared with all the other groups. Examination of the fractured specimens of GC, G D and G Eusing stereo microscope revealed that for Group C and group D,70%and 50% cohesive failure respectively while forgroup E 70% showed adhesive failure.Conclusion: Posterior composite resin restoration whatever material type used for packing it, showed a greatimprovement in the resistance to cuspal fracture, Silorane based composite show little improvement in fractureresistance by means value in comparison to methacrylate based composite although statistically there is nosignificant difference between them.Key words: low shrinkage composite, fracture strength of teeth, silorane based resin composite. (J Bagh Coll Dentistry2011;23(3): 30-36).

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