Three-Dimensional Micro-CT Assessment of Radiopacity and Intra-Cavity Distribution of Universal Adhesives

Area of Science:

• Dental Materials Science
• Biomaterials
• Radiology

Background:

• Radiopacity of dental adhesives is critical for radiographic diagnosis and micro-computed tomography (micro-CT) evaluation.
• Most universal adhesives exhibit insufficient radiopacity, potentially leading to misdiagnosis.

Purpose of the Study:

• To evaluate and compare the radiopacity and intracavity distribution of four universal adhesives.
• To determine if any universal adhesive offers dentin-equivalent radiopacity for improved diagnostic imaging.

Main Methods:

• A cylindrical cavity model in bovine enamel-dentin blocks was used.
• Micro-computed tomography (micro-CT) scans were performed after preparation, adhesive application, and composite filling (n=3).
• Adhesive layer analysis utilized 16-bit grayscale values and 3D difference analysis.

Main Results:

• Scotchbond Universal Plus Adhesive (SBP) demonstrated dentin-equivalent radiopacity.
• Scotchbond Universal Adhesive (SBU), Clearfil Universal Bond Quick ER (UBQ), and G-Premio Bond (GPB) were indistinguishable from air.
• Adhesive thickness varied within cavities, with reduced-density regions noted in UBQ and GPB.

Conclusions:

• SBP is the sole universal adhesive tested with dentin-equivalent radiopacity, facilitating reliable micro-CT evaluation.
• This finding reduces the risk of radiographic misdiagnosis in adhesive restorations.
• A grayscale-based approach shows potential for non-destructive analysis of dental adhesives.