A predictive formula of the contraction stress in restorative and luting materials attending to free and adhered surfaces, volume and deformation.
OBJECTIVE
To find a predictive formula of stress, considering the surfaces (free, adhered) involved, the volume and characteristics of material and the deformation of the measuring system.


METHODS
231 samples of five chemically cured restoratives (Silar (SIL, 23), Clearfil F2 (CLE, 39), P10 (P10, 33), Concise (CON, 30), Isopast (ISO, 28)) and four luting (3M Experimental 241 (EXM, 20), Variolink II (VAR, 13), Vitremer LC (VTM, 20) and Dyract Cem (DYR, 25)) materials were allowed to polymerize until they reached a maximum tension (T(max), 25 min) between six pairs (null 5.81, 8.5, 11.26, 12.42, 17.02, 23.14 mm) of polished metallic discs (range of distances: 0.02-5.9 mm) mounted in a tension machine. The deformation of the measuring system was measured for the recorded forces.


RESULTS
A descriptive non-linear formula T(max)=KVol(-3.267)FS(3.283)AS(0.642)Def(0.561) was found that individualizes the material's characteristics (K) that considers volume (Vol), free (FS) and adhered (AS) surfaces and deformation (Def) of the system for each force. This formula renders good correlation (material K (r(2) coefficient)): SIL 0.9998 (0.995), CLE 1.0062 (0.989), P10 1.0224 (0.990), CON 0.9908 (0.992), ISO 0.9648 (0.974), EXM 1.0083 (0.991), VAR 0.9777 (0.996), VTM 0.9925 (0.993), DYR 0.9971 (0.997) between actual T(max) and calculated Tension. There are statistically significant differences (p=0.002) between K values of both (restorative and luting) groups.


CONCLUSIONS
Predictive parameters have influence in a different way to what is actually considered, if the system is allowed to have deformation, as occurs naturally and volume and material's characteristics are considered.
Miguel
A
A
Conservative Dentistry Department, Faculty of Odontology, Complutense University, Madrid, Spain.
de la Macorra
J C
JC
D000180:Acrylic Resins / Q000737:chemistry; D000268:Adhesiveness; D000465:Algorithms; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D020770:Compomers / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry; D003722:Dental Alloys / Q000737:chemistry; D003738:Dental Cements / Q000737:chemistry; D003764:Dental Materials / Q000737:chemistry*; D003793:Dental Restoration, Permanent; D005544:Forecasting; D005899:Glass Ionomer Cements / Q000737:chemistry; D006801:Humans; D008689:Methacrylates / Q000737:chemistry; D008956:Models, Chemical; D017711:Nonlinear Dynamics; D011140:Polyurethanes / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry; D017640:Silicates / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013500:Surface Tension
D000180:Acrylic Resins; D020770:Compomers; C029012:Composite Dental Resin; D003188:Composite Resins; D003722:Dental Alloys; D003738:Dental Cements; D003764:Dental Materials; C088486:Dyract; D005899:Glass Ionomer Cements; C513707:Isopast; D008689:Methacrylates; D011140:Polyurethanes; D019279:Resin Cements; D017640:Silicates; C084550:Vitremer; C103502:Variolink; D017438:Bisphenol A-Glycidyl Methacrylate; C033930:Silar (3M); C086115:Clearfil F2; C067318:P10 dental resin