The Effect of Fillers in Dental Resins

Fillers used in photopolymer resins (dental resins) are solid particles added to improve the performance of the material. However, fillers can cause some undesirable effects. These include reduced fluidity of the resin, uneven distribution of the material leading to surface roughness, yellowing issues, settling at the base during curing, and the deterioration of uniform printing quality. These negative effects can cause significant problems in dental applications that require high precision.

Negative Effects of Fillers in the Dental Sector

1. Printing Quality

• Surface Roughness: When fillers are not homogeneously distributed, surface roughness occurs, which creates problems in precise dental applications.
• Printer Compatibility: The size and type of fillers affect the viscosity and photopolymerization of the resin, which can disrupt the printer's smooth operation.

1. Photopolymerization Issues

• Light Transparency: A high filler ratio reduces light permeability, leading to incomplete curing (under-curing), which prevents achieving the full mechanical properties.
• Low Resin Performance: Fillers can increase internal stresses during photopolymerization, leading to deformations.

1. Material Durability

• Brittleness: Incorrectly formulated fillers can make the material brittle, jeopardizing the durability of dental restorations.
• Wear: Hard fillers can cause the resin to wear out, shortening the lifespan of restorations.

1. Effects on Devices and Equipment

• Resin Tank Wear: Fillers can wear down the resin tank used in the printer and damage optical components.
• Filtration Problems: A high filler ratio increases the viscosity of the resin, requiring more frequent tank cleaning.

1. Biocompatibility Issues

• Toxicity: Some fillers may not be biocompatible and can cause side effects in dental restorations used in the mouth.
• Low Aesthetics: Fillers reduce light permeability after printing, making it difficult to achieve a natural tooth appearance.

1. Storage and Stability

• Sedimentation: Fillers may settle over time, requiring the resin to be mixed before each use.

By examining the printing results and the problems that may arise in a patient’s mouth, it is possible to understand the impact of fillers used in resins. Issues such as surface roughness, loss of detail, or incomplete curing in prints may indicate that the fillers have not been homogeneously distributed or that the resin formulation has not been properly optimized. Additionally, restorations made with these resins can cause issues like breakage, wear, biocompatibility problems, and yellowing over time, leading to aesthetic concerns. Especially toxic effects, an unnatural appearance, or the restoration deforming quickly, are signs that the fillers used are of poor quality or incompatible. Such situations severely affect both printing quality and patient satisfaction.

While fillers improve the performance of photopolymer resins, they can negatively impact printing quality, aesthetics, and durability. CRS resins, on the other hand, provide high strength without the use of fillers.