A new method of evaluation of fracture patterns following microtensile bond strength testing using polarized light microscopy.
OBJECTIVE
This work describes a new method using polarized light microscopy to determine the failure modes of fractured beams following microtensile bond strength testing. The outcomes were validated using SEM and EDX elemental analysis.


METHODS
Resin adhesives and resin composites bonded to caries-free dentin samples as well as disks of adhesive and composite were observed with reflected polarized light microscopy (PLM) to obtain standard images. A set of beams fractured in the microtensile bond test were observed with PLM and compared with the standard images to determine failure mode through PLM color matching with the standard dentin, adhesive, or composite images. Samples were analyzed by EDX under SEM and compared with the PLM outcomes.


RESULTS
Reflected PLM images showed that the fractured surfaces covered with resin-based materials (adhesives or composite) appeared pink in color, in contrast to dentin surfaces, which appeared yellow. EDX mapping together with SEM observation confirmed the results obtained by PLM.


CONCLUSIONS
The results of EDX mapping and SEM observation showed that the use of polarized light microscopy is a simple, viable method for differentiation between the resin-covered dentin surfaces for determining fracture pattern analysis after bond testing.
Hamdi H
HH
Hamama
Cynthia K Y
CK
Yiu
Michael F
MF
Burrow
D001565:Benzoates / Q000737:chemistry; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D003116:Color; D003188:Composite Resins / Q000737:chemistry*; D001840:Dental Bonding; D003804:Dentin / Q000648:ultrastructure; D017220:Dentin-Bonding Agents / Q000737:chemistry; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D008859:Microscopy, Polarization / Q000379:methods*; D053761:Nanocomposites / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D011140:Polyurethanes / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry*; D013052:Spectrometry, X-Ray Emission; D013314:Stress, Mechanical; D013499:Surface Properties; D013718:Tensile Strength
D001565:Benzoates; C520091:CeramX; C505694:Clearfil S3 Bond; C438313:Clearfil SE Bond; D003188:Composite Resins; D017220:Dentin-Bonding Agents; C444701:Filtek Z250; D008689:Methacrylates; D011109:Polymethacrylic Acids; D011140:Polyurethanes; C425843:Prime and Bond NT; D019279:Resin Cements; C029824:urethane dimethacrylate luting resin; C080129:pyromellitic dianhydride glycerol dimethacrylate adduct; C020946:triethylene glycol dimethacrylate; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate; C041330:Scotchbond; C090921:1,6-hexanediol dimethacrylate; C028643:trimethylolpropane trimethacrylate