Bruxism is one of the greatest challenges in restorative dentistry. Grinding and clenching generate extremely high occlusal forces, resulting in exceptional loads on the restoration, regardless of the material. Modern hybrid materials offer a biomechanically sound solution. However, studies also show that it is not just the material and its properties that matter. Surface finishing plays an equally important role.
Bruxism patients generate elevated occlusal forces that generally go beyond normal functional loads. This can lead to various problems in prosthetic restorations, such as cohesive partial fractures (especially in brittle ceramics), chipping, increased abrasion, or premature material failure. Research and clinical experience demonstrate that the material itself can only compensate for such high stress peaks to a limited extent.
Biomechanical balance instead of maximum hardness
A paradigm shift is taking place in restorative treatments for bruxism patients. The focus is shifting, away from maximum strength toward biomechanical balance. Suitable materials must provide uniform force distribution, attenuate peak stresses, and preserve the natural tooth structure. And this is where modern hybrid materials come into play.
Hybrid materials at a glance
Hybrid ceramics are two-phase materials in which inorganic and organic components combine to form a finely cross-linked hybrid structure.
1. The ceramic phase provides dimensional stability, hardness, and chemical resistance.
2. The polymer phase acts as an elastic matrix that distributes stress and reduces susceptibility to fracture.
From a materials science perspective, these materials occupy a true hybrid position — ceramic‑like in their structural concept, yet polymer‑like in their mechanical response.
- Elastic modulus: Compared with conventional ceramics, the elastic modulus is more closely matched to enamel and dentin, enabling more balanced load transfer and a reduction in peak stresses.
- Abrasion behavior: The wear characteristics are comparable to those of natural teeth. Polished hybrid materials glide over the antagonist rather than wearing it down.
- Shock-absorbing properties: The combination of filler and matrix absorbs short-term stress peaks—an advantage during parafunctional activity.
Clinical advantages at a glance:
- Elastic absorption of high oclusal forces
- Protection of the opposing dentition
- Reduced fracture risk under functional overload
- Efficient CAD/CAM processing
The underestimated role of the surface
But even the best material is only as good as its surface. This relationship is particularly evident in bruxism. Confocal microscopic analyses show that professional polishing agents for dental restorations, such as suitable diamond polishing pastes, can reduce surface roughness (Sa value) by up to 93%—from approximately 0.35 µm to values between 0.02 and 0.04 µm. This has a direct impact on clinically relevant factors: reduced plaque accumulation, more homogeneous force distribution, and a more stable surface structure.
Clinically speaking:
- Rough surfaces promote plaque, microtrauma, and stress cracks.
- Well-polished surfaces distribute forces and maintain the material’s elasticity.
For detailed polishing protocols, scientific background, and professional techniques, read our ultimate guide to polishing CAD/CAM restorations.
Polishing hybrid materials: Two materials – one surface
Polishing hybrid materials is challenging. These materials combine ceramic fillers (hard, brittle, easy to polish) and polymer matrix components (softer, elastic, prone to smearing). This duality requires a protocol that allows both components to be processed evenly.
Practical tip: Use a specialized polishing protocol!
Standard polishing pastes, developed for pure ceramics or pure resins, reach their limits when used on hybrid materials.
The solution: Specialized polishing systems
Renfert Polish hybrid materials is a polishing agent tailored to the material structure of hybrid materials. The diamond-based formulation accounts for the differing hardnesses and wetting behavior of both phases. This results in reproducibly homogeneous high-gloss surfaces; without smearing effects or uneven removal.
Confocal 3D microscopy reveals the elimination of process‑related surface marks resulting in a continuous, topographically homogeneous surface with stable reflectance.
Practical tip: Keep intervals short!
Polishing in short intervals helps limit temperature buildup and preserve the stability of the matrix structure.
