title: The use of micro-CT with image segmentation to quantify leakage in dental restorations.
abstract: OBJECTIVE
  To develop a method for quantifying leakage in composite resin restorations after curing, using non-destructive X-ray micro-computed tomography (micro-CT) and image segmentation.
  
  
  METHODS
  Class-I cavity preparations were made in 20 human third molars, which were divided into 2 groups. Group I was restored with Z100 and Group II with Filtek LS. Micro-CT scans were taken for both groups before and after they were submerged in silver nitrate solution (AgNO3 50%) to reveal any interfacial gap and leakage at the tooth restoration interface. Image segmentation was carried out by first performing image correlation to align the before- and after-treatment images and then by image subtraction to isolate the silver nitrate penetrant for precise volume calculation. Two-tailed Student's t-test was used to analyze the results, with the level of significance set at p<0.05.
  
  
  RESULTS
  All samples from Group I showed silver nitrate penetration with a mean volume of 1.3 ± 0.7mm(3). In Group II, only 2 out of the 10 restorations displayed infiltration along the interface, giving a mean volume of 0.3 ± 0.3mm(3). The difference between the two groups was statistically significant (p<0.05). The infiltration showed non-uniform patterns within the interface.
  
  
  CONCLUSIONS
  We have developed a method to quantify the volume of leakage using non-destructive micro-CT, silver nitrate infiltration and image segmentation. Our results confirmed that substantial leakage could occur in composite restorations that have imperfections in the adhesive layer or interfacial debonding through polymerization shrinkage. For the restorative systems investigated in this study, this occurred mostly at the interface between the adhesive system and the tooth structure.
authors: Minnesota Dental Research Center for Biomaterials and Biomechanics, School of Dentistry, University of Minnesota, Minneapolis, MN, USA.
authors: Carola A
authors: CA
authors: Carrera
authors: Minnesota Dental Research Center for Biomaterials and Biomechanics, School of Dentistry, University of Minnesota, Minneapolis, MN, USA.
authors: Caixia
authors: C
authors: Lan
authors: Department of Aerospace Engineering and Mechanics, University of Minnesota, Minneapolis, MN, USA.
authors: David
authors: D
authors: Escobar-Sanabria
authors: Minnesota Dental Research Center for Biomaterials and Biomechanics, School of Dentistry, University of Minnesota, Minneapolis, MN, USA.
authors: Yuping
authors: Y
authors: Li
authors: Department of Diagnostic and Biological Sciences, School of Dentistry, University of Minnesota, Minneapolis, MN, USA.
authors: Joel
authors: J
authors: Rudney
authors: Minnesota Dental Research Center for Biomaterials and Biomechanics, School of Dentistry, University of Minnesota, Minneapolis, MN, USA.
authors: Conrado
authors: C
authors: Aparicio
authors: Minnesota Dental Research Center for Biomaterials and Biomechanics, School of Dentistry, University of Minnesota, Minneapolis, MN, USA. Electronic address: alexfok@umn.edu.
authors: Alex
authors: A
authors: Fok
mesh_terms: D003188:Composite Resins / Q000737:chemistry*; D001840:Dental Bonding; D003737:Dental Cavity Preparation; D003763:Dental Leakage / Q000000981:diagnostic imaging*; D003793:Dental Restoration, Permanent; D006801:Humans; D066298:In Vitro Techniques; D008964:Molar, Third / Q000000981:diagnostic imaging; D012835:Silver Nitrate / Q000737:chemistry*; D055114:X-Ray Microtomography / Q000379:methods*
chemical_list: D003188:Composite Resins; D012835:Silver Nitrate
keywords: Composite resins; Dental adhesives; Interfacial debonding; Leakage; Micro-CT; Secondary caries
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