Preheated and Injected Bulk-Fill Resin Composites: A Micro-CT Analysis of Internal Voids and Marginal Adaptation in...

Area of Science:

• Dental Materials Science
• Restorative Dentistry
• Biomaterials Engineering

Background:

• Class II cavities are common dental restorations requiring precise material adaptation.
• Bulk-fill resin composites offer potential advantages over traditional incremental techniques.
• Void formation and marginal integrity are critical factors influencing restoration longevity.

Purpose of the Study:

• To evaluate in vitro void formation and marginal adaptation of bulk-fill resin composites.
• To compare preheated versus non-preheated materials and injected versus incremental techniques.
• To assess different bulk-fill composite materials for their performance in Class II cavities.

Main Methods:

• Eighty human molars with Class II cavities were restored using four bulk-fill materials (Filtek Universal, Filtek One, Admira Fusion X-tra, VisCalor) at 24°C or 68°C.
• Micro-computed tomography (micro-CT) was used to analyze internal void percentage (%IV).
• Marginal adaptation was assessed by the percentage of continuous margins (%CM) in enamel and dentin.

Main Results:

• Bulk-fill materials, particularly Filtek One and VisCalor, exhibited significantly lower internal voids compared to the control.
• Preheating VisCalor significantly reduced internal voids.
• No significant influence of temperature on marginal adaptation was observed.
• VisCalor demonstrated superior marginal adaptation in dentin at 24°C.

Conclusions:

• Injected bulk-fill resin composites generally result in fewer internal voids than conventional incremental techniques.
• The injection method appears more critical for achieving good marginal adaptation than material preheating.
• Specific bulk-fill materials and techniques can optimize void reduction and marginal integrity in Class II restorations.