Three-Dimensional Internal Voids and Marginal Adaptation in Deep Margin Elevation Technique: Efficiency of Highly...

Area of Science:

• Restorative Dentistry
• Biomaterials Science
• Dental Materials

Background:

• Accurate marginal adaptation of dental restorations is crucial for preventing secondary caries and ensuring longevity.
• Flowable composites are utilized in deep margin elevation (DME) procedures, but their interfacial integrity under stress requires evaluation.
• Understanding material behavior in challenging clinical scenarios like DME is essential for optimizing restorative outcomes.

Purpose of the Study:

• To assess the three-dimensional interfacial adaptation and internal voids of various flowable composites.
• To compare material performance before and after cyclic fatigue in a simulated deep-margin elevation (DME) scenario.
• To investigate the influence of different flowable composite viscosities on marginal integrity.

Main Methods:

• Eighty extracted premolars underwent Class II cavity preparation with margins above and below the cementum-enamel junction (CEJ).
• Four groups of flowable composites (nanohybrid, conventional, medium, high viscosity) were used for 2 mm horizontal deep-margin relocation.
• Micro-computed tomography (micro-CT) was employed to analyze interfacial gaps and internal voids before and after 500,000 cycles of mechanical fatigue.

Main Results:

• At baseline, a highly filled medium viscosity composite demonstrated significantly better interfacial adaptation compared to a conventional viscosity composite.
• No significant differences in internal voids were observed among the tested materials at baseline.
• Following mechanical aging, no significant differences in interfacial gap progression were found across the different restorative materials or substrates.

Conclusions:

• Highly filled medium viscosity flowable composites offer superior baseline interfacial adaptation in deep margin elevation compared to conventional viscosity types.
• Cyclic mechanical loading and thermocycling did not adversely affect the interfacial gap progression of the evaluated restorative materials.
• All tested restorative materials exhibited comparable performance regarding interfacial gap progression after aging, suggesting resilience in this simulated clinical context.