Measurement of the internal adaptation of resin composites using micro-CT and its correlation with polymerization shrinkage.

In the present study, the internal adaptation of dentin-composite interfaces with various resin composite materials under conditions of thermomechanical loading was analyzed nondestructively using micro-computed tomography (micro-CT), and these results were compared with analyses of microgaps after sectioning. Additionally, the correlation of internal adaptation with polymerization shrinkage strain and stress was evaluated. Four nonflowable resins, Gradia Direct (GD), Filtek P90 (P9), Filtek Z350 (Z3), and Charisma (CH), and two flowable resins, SDR (SD) and Tetric N-Flow (TF) were used. First, the polymerization shrinkage strain and stress were measured. Then, Class I cavities were prepared in 48 premolars. They were divided randomly into six groups, and the cavities were filled with composites using XP bond. To evaluate the internal adaptation, tooth specimens were immersed in a 25% silver nitrate solution, and micro-CT analysis was performed before and after thermomechanical loading. The silver nitrate penetration (%SP) was measured. After buccolingual sectioning and rhodamine penetration of the specimen, the rhodamine penetration (%RP) was measured using a stereo-microscope. One-way analysis of variance was then used to compare the polymerization shrinkage strain, stress, %SP, and %RP among the groups at a 95% confidence level. A paired t-test was used to compare the %SP before and after thermomechanical loading. Pearson correlation analysis was used to compare the correlation between polymerization shrinkage strain/stress and %SP or %RP to a 95% confidence level. Evaluation of the polymerization shrinkage strain demonstrated that P9 < Z3 ≤ GD < CH ≤ SD < TF (p<0.05); similarly, evaluation of the polymerization shrinkage stress showed that P9 ≤ GD ≤ Z3 ≤ CH ≤ SD < TF (p<0.05). The %SP showed that P9 ≤ GD ≤ Z3 < CH ≤ SD < TF (p<0.05) before loading and that P9 ≤ GD ≤ Z3 ≤ CH ≤ SD < TF (p<0.05) after loading. There was a significant difference between the before-loading and after-loading measurements in all groups (p<0.05). Additionally, there was a positive correlation between the %SP and the %RP (r=0.810, p<0.001). Conclusively, the polymerization shrinkage stress and strain were found to be closely related to the internal adaptation of the resin composite restorations. The newly proposed model for the evaluation of internal adaptation using micro-CT and silver nitrate may provide a new measurement for evaluating the internal adaptation of restorations in a nondestructive way.

[1]  J. Ferracane,et al.  Assessing the effect of composite formulation on polymerization stress. , 2000, Journal of the American Dental Association.

[2]  C. Splieth,et al.  Polymerization shrinkage-strain and microleakage in dentin-bordered cavities of chemically and light-cured restorative materials. , 2002, Dental materials : official publication of the Academy of Dental Materials.

[3]  Jack L Ferracane,et al.  Factors involved in the development of polymerization shrinkage stress in resin-composites: a systematic review. , 2005, Dental materials : official publication of the Academy of Dental Materials.

[4]  I. Krejci,et al.  In vitro evaluation of marginal and internal adaptation after occlusal stressing of indirect class II composite restorations with different resinous bases and interface treatments. “Post-fatigue adaptation of indirect composite restorations” , 2003, Clinical Oral Investigations.

[5]  Xi Chen,et al.  Optimal use of silver nitrate and marginal leakage at the sealant-enamel interface using micro-CT. , 2009, American journal of dentistry.

[6]  C. G. Toh,et al.  Detection of microleakage around dental restorations: a review. , 1997, Operative dentistry.

[7]  Sung-Ho Park,et al.  Evaluation of internal adaptation of dental adhesive restorations using micro-CT , 2012 .

[8]  Sheng Lin-Gibson,et al.  Evaluation of dental composite shrinkage and leakage in extracted teeth using X-ray microcomputed tomography. , 2009, Dental materials : official publication of the Academy of Dental Materials.

[9]  C. Davidson,et al.  Polymerization shrinkage and polymerization shrinkage stress in polymer-based restoratives. , 1997, Journal of dentistry.

[10]  V. Tserki,et al.  Study of water sorption, solubility and modulus of elasticity of light-cured dimethacrylate-based dental resins. , 2003, Biomaterials.

[11]  J. Ferracane,et al.  Polymerization stress, shrinkage and elastic modulus of current low-shrinkage restorative composites. , 2010, Dental materials : official publication of the Academy of Dental Materials.

[12]  J. Ferracane,et al.  Polymerization contraction stress in dual-cure cements and its effect on interfacial integrity of bonded inlays. , 2002, Journal of dentistry.

[13]  R. Braga,et al.  Polymerization contraction stress of low-shrinkage composites and its correlation with microleakage in class V restorations. , 2004, Journal of dentistry.

[14]  F. Tay,et al.  Water treeing--a potential mechanism for degradation of dentin adhesives. , 2003, American journal of dentistry.

[15]  D. Droz,et al.  Microleakage and polymerization shrinkage of various polymer restorative materials. , 2008, Journal of dentistry for children.

[16]  W. D’hoore,et al.  Influence of the number of sections on reliability of in vitro microleakage evaluations. , 2003, American journal of dentistry.

[17]  D. Watts,et al.  3D-marginal adaptation versus setting shrinkage in light-cured microhybrid resin composites. , 2007, Dental materials : official publication of the Academy of Dental Materials.

[18]  Sheng Lin-Gibson,et al.  3D mapping of polymerization shrinkage using X-ray micro-computed tomography to predict microleakage. , 2009, Dental materials : official publication of the Academy of Dental Materials.

[19]  R. Hickel,et al.  Low-shrinkage composite for dental application. , 2007, Dental materials journal.

[20]  Luigi Nicolais,et al.  A 3D analysis of mechanically stressed dentin-adhesive-composite interfaces using X-ray micro-CT. , 2005, Biomaterials.

[21]  Young-Joo Kim,et al.  AMOUNT OF POLYMERIZATION SHRINKAGE AND SHRINKAGE STRESS IN COMPOSITES AND COMPOMERS FOR POSTERIOR RESTORATION , 2003 .

[22]  J. Ferracane,et al.  Alternatives in polymerization contraction stress management. , 2004, Journal of applied oral science : revista FOB.

[23]  J. Ferracane,et al.  Contraction stress of low-shrinkage composite materials assessed with different testing systems. , 2010, Dental materials : official publication of the Academy of Dental Materials.

[24]  Hidehiko Sano,et al.  In vitro degradation of resin-dentin bonds analyzed by microtensile bond test, scanning and transmission electron microscopy. , 2003, Biomaterials.

[25]  Hong Lin,et al.  Comparison between a silorane-based composite and methacrylate-based composites: shrinkage characteristics, thermal properties, gel point and vitrification point. , 2012, Dental materials journal.

[26]  J. Bausch,et al.  Clinical significance of polymerization shrinkage of composite resins. , 1982, The Journal of prosthetic dentistry.

[27]  R. Hickel,et al.  Investigations on a methacrylate-based flowable composite based on the SDR™ technology. , 2011, Dental materials : official publication of the Academy of Dental Materials.

[28]  A. Peutzfeldt,et al.  Determinants of in vitro gap formation of resin composites. , 2004, Journal of dentistry.

[29]  S. Duarte,et al.  Effect of low-elastic modulus liner and base as stress-absorbing layer in composite resin restorations. , 2010, Dental materials : official publication of the Academy of Dental Materials.

[30]  R. Frankenberger,et al.  Marginal quality of flowable 4-mm base vs. conventionally layered resin composite. , 2011, Journal of dentistry.

[31]  M. A. Sinhoreti,et al.  Effect of the curing method and composite volume on marginal and internal adaptation of composite restoratives. , 2011, Operative dentistry.

[32]  A. Versluis,et al.  Do Low-shrink Composites Reduce Polymerization Shrinkage Effects? , 2011, Journal of dental research.

[33]  W. Weinmann,et al.  Siloranes in dental composites. , 2005, Dental materials : official publication of the Academy of Dental Materials.

[34]  M. Torii,et al.  Polymerization contraction stress of resin composite restorations in a model Class I cavity configuration using photoelastic analysis. , 2000, Journal of esthetic dentistry.