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 ± 0.7 mm3. In Group II, only 2 out of the 10 restorations displayed infiltration along the interface, giving a mean volume of 0.3 ± 0.3 mm3. The difference between the two groups was statistically significant (p < 0.05). The infiltration showed non-uniform patterns within the interface. Significance 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.

Is there correlation between polymerization shrinkage, gap formation, and void in bulk fill composites? A μCT study

“…In recent years, μCT has become an important tool in the analysis of polymerization shrinkage, 22,23 gap formation, 24 and void. 16 μCT can produce quantitative analyses of polymerization shrinkage when compared with conventional methods, which are qualitative or semiquantitative.…”

“…The volume of polymerization shrinkage, gap, and void was calculated through the analysis of the anatomical structure of the restoration and was expressed as percentage. 24 …”

“…Therefore, the analysis in μCT has become an accurate, safe, and non-destructive method for evaluating these materials in 3D. 19,24 Both bulk fill and conventional RCs presented voids in the body of the material (Table 2), but a smaller void volume was found for conventional RCs. There was no difference in void volume among bulk fill composites.…”

“…This type of analysis eliminates the need for cuts and stresses to the tooth, unlike other methods, such as scanning electron microscopy (SEM). 19 μCT is a safe and nondestructive method that can analyze the material in 3D, 24 but it is infrequently used to quantify spaces and voids in restorative materials.…”

Micro-computerized tomography analysis of cement voids and pull-out strength of glass fiber posts luted with self-adhesive and glass-ionomer cements in the root canal

“…It has promising applications in different fields of dentistry [17,26,27]. The influence of the cement thickness on bond strength of fiber posts has been evaluated using longitudinal sectioning prior to photographic and microscopic analysis but this technique can also lead to loss of cement material during sectioning [x].…”