Comparison between different flow application techniques: SDR vs flowable composite.

Area of Science:

• Dental Materials Science
• Restorative Dentistry
• Biomaterials Engineering

Background:

• Marginal adaptation is crucial for the longevity of dental restorations.
• Flowable composites are often used as a first increment in Class II cavities.
• Understanding the effect of layer thickness on marginal integrity is essential for clinical success.

Purpose of the Study:

• To investigate how varying layer thicknesses of flowable composites affect the marginal adaptation of Class II fillings.
• To assess the impact of thermomechanical loading (TML) on marginal adaptation in relation to composite layer thickness.

Main Methods:

• Sixty Class II box cavities were prepared with gingival margins in dentin.
• Samples were divided into six groups, using different flowable composites (SDR, x-Flow) and nanohybrid composite (Ceram.X mono) in 1mm or 4mm first increments.
• Marginal adaptation was evaluated using scanning electron microscopy before and after thermomechanical loading (TML).

Main Results:

• The x-Flow material, when applied as a 4mm increment (Group F), showed compromised marginal adaptation in dentin before TML.
• After TML, Group F exhibited significantly worse marginal adaptation compared to most other groups.
• The marginal integrity of all interfaces was significantly compromised in Group F compared to all other groups, both before and after TML.

Conclusions:

• The application technique and thickness of flowable composite first increments influence marginal adaptation in Class II cavities.
• A 4mm first increment of Ceram.X mono and SDR did not negatively affect marginal adaptation compared to a 1mm increment.
• The x-Flow material, particularly at a 4mm increment, demonstrated inferior marginal adaptation under thermomechanical stress.