Wavelength-Dependent Transmitted Irradiance Through Lithium Disilicate Ceramics

Area of Science:

• Dental Materials Science
• Photopolymerization
• Biomaterials Engineering

Background:

• Conventional camphorquinone-based resin cements have limitations with light penetration.
• Novel photoinitiator systems utilizing longer wavelengths are under development.
• Understanding light transmission through dental ceramics is crucial for effective photopolymerization.

Purpose of the Study:

• To evaluate the transmitted irradiance of blue and red light through lithium disilicate ceramics.
• To determine if longer wavelengths provide enhanced light delivery compared to shorter wavelengths.
• To assess the influence of ceramic translucency, shade, and thickness on light transmission.

Main Methods:

• Lithium disilicate blocks (IPS e.max CAD) with varying translucencies (HT, MT, LT) and shades (A1, A2, A3) were used.
• Ceramic samples were sectioned to thicknesses ranging from 0.5 to 3.0 mm.
• Transmitted irradiance of standardized blue and red LEDs was measured using a spectrometer system.

Main Results:

• Ceramic thickness, light source, translucency, and shade all significantly influenced transmitted irradiance (p < 0.001).
• Ceramic thickness had the greatest impact on irradiance, followed by the light source.
• Red light demonstrated significantly higher transmitted irradiance than blue light across all tested conditions.

Conclusions:

• Wavelength significantly affects transmitted irradiance through lithium disilicate ceramics.
• Red light penetrates lithium disilicate ceramics more effectively than blue light.
• These findings support the use of longer wavelengths for improved light delivery in dental applications.