Influence of different thermopolymerization methods on composite resin microhardness

Area of Science:

• Dental Materials Science
• Polymer Chemistry
• Biomaterials Engineering

Background:

• Additional heat polymerization enhances composite resin properties like microhardness and color stability.
• Understanding the impact of different heat polymerization methods is crucial for optimizing dental restorations.

Purpose of the Study:

• To compare the effects of autoclave and microwave thermopolymerization on the microhardness of various dental composite resins.
• To evaluate the influence of resin composition on microhardness after different polymerization techniques.

Main Methods:

• 150 composite resin specimens of five different types were prepared.
• Three polymerization methods were tested: light curing only, photopolymerization + autoclave, and photopolymerization + microwave.
• Vickers microhardness testing was performed on all specimens.

Main Results:

• Highest microhardness averages were observed in Filtek P60 and Filtek Z250 XT resins with light curing only.
• Brilliant Everglow resin consistently showed the lowest microhardness averages across all polymerization methods.
• Thermopolymerization increased microhardness for Brilliant Everglow and Filtek One Bulkfill but decreased it for Filtek P60, Filtek Z350XT, and Filtek Z250XT.

Conclusions:

• Autoclave and microwave thermopolymerization methods exhibited similar effects on composite resin microhardness.
• The impact of thermopolymerization on microhardness is resin-dependent, with some composites showing increased values and others showing decreased values.