Laser-assisted melt printing: Glass and ceramics directly from the printer

A related study was conducted with then doctoral researcher Dr Isabell-Sophie Teegen, who later published the findings as lead author in Dental Materials.² Dr Siebert pointed out that this project marked an important milestone and raised a fundamental question: how can the energy-intensive sintering process be avoided?

“The printed specimens had to be sintered in a furnace for more than 7 hours at 1,700 °C—a considerable time and energy requirement,” Dr Siebert recalled. Initial attempts to melt zirconia directly using high-performance lasers showed promise. However, at the extreme melting temperatures required, there was no direct way to determine in real time whether the component had become fully dense or whether internal porosities remained.

Glass as a model system

Glass proved to be a suitable model material because it melts at lower temperatures and, owing to its transparency, allows direct visual monitoring of the melting process. “We needed a system where we could directly see whether melting was occurring as intended,” Dr Siebert explained. These properties made glass an appropriate system for evaluating the laser parameters.

Using a specially developed silica-based particle ink, the team deposited thin layers and melted each layer with high-energy laser pulses. “The first 3D specimens were fascinating, especially when you could partially see through them,” Dr Siebert said. This was the moment that it became clear that the concept had significant potential.

The principle of LAMP is straightforward, but the process is technically demanding. During additive fabrication, laser pulses selectively melt the particles, fusing each layer and densifying the material immediately. No post-printing sintering is required. Microscopy and spectroscopic analyses confirmed full densification and low porosity under optimised settings, representing a clear distinction from many previous approaches to glass 3D-printing.

“LAMP allows physical properties such as density, smoothness, colour and transparency to be controlled directly during printing,” Dr Siebert said. By adjusting laser power and scanning speed, surface quality and material characteristics can be tailored during printing. For additive manufacturing, this means a direct link between process parameters and material microstructure.

Relevance to dental manufacturing

In dental production, milling of ceramic implants and restorations from pre-sintered blanks results in substantial material loss. “Up to 90% of the blank can end up as milling waste, but the method continues to be used because every restoration is unique,” Dr Siebert said.

Although additive manufacturing significantly reduces waste, it usually still requires post-printing sintering in a furnace. “Using our process, a fully finished dental implant could emerge directly from the printer, perhaps requiring polishing but otherwise complete,” he said. Eliminating furnace sintering not only reduces energy consumption but also shortens the workflow.

Dr Siebert outlined a possible future scenario: “A dental implant could be ready within just a few hours using this process.” From a materials science perspective, a workflow involving an intra-oral scan in the morning and restoration that same day appears theoretically feasible.

Rethinking mechanics: Elastic microstructures

Beyond time and energy considerations, Dr Siebert highlighted the design freedom enabled by additive manufacturing. “Using conventional furnace processes, it is possible to achieve acceptable mechanical properties,” he said. “However, 3D printing offers the additional possibility of integrating elastic structures.”

An implant could exhibit a hard surface while maintaining a more elastic overall architecture, closer to the biomechanical behaviour of natural teeth. “Current implants are very rigid, which may contribute to wear of opposing natural teeth over time,” he said. Additive manufacturing could incorporate internal lattice-like features to reduce rigidity and help distribute forces more like natural teeth.

Optical properties as a design parameter

According to Dr Siebert, LAMP could also enable aesthetic customisation. By adjusting laser parameters, transparency and surface finish can be modified. The team also incorporated gold and silver ions into the printing ink, and these formed metallic nanoparticles during laser melting.

“These nanoparticles act like tiny optical filters. They allow specific wavelengths to pass through but block others,” Dr Siebert said. This means that colour perception can be influenced by the particles included and their size and distribution. The publication in Materials and Design demonstrates how optical properties can be deliberately tuned.

In dentistry, this could eventually enable patient-specific customisation with the aim of achieving restorations that are visually indistinguishable from natural dentition. “In the long term, it may even be possible to combine multiple ceramic pastes to precisely tailor colour and translucency,” Dr Siebert said.

Functional additives and new materials

The flexibility of paste formulation provides additional possibilities. “We can incorporate antibacterial agents such as zinc oxide into the paste,” Dr Siebert said. In small concentrations, such additives could be integrated into the implant for release near the surface once in situ.

He also pointed out the value of the technology as a tool for materials research. “Some materials are not currently used because slow cooling in a furnace is problematic,” he said. The rapid heating and cooling rates of the laser process could enable new material compositions. “This is particularly exciting for dental research,” Dr Siebert said.

An enabling technology

To date, LAMP has been demonstrated using glass, but the goal remains its transfer to high-performance dental ceramics such as zirconia or lithium disilicate. “Glass was the most logical starting point for developing the process,” Dr Siebert said.

Significant materials challenges remain. However, the approach has potential as a platform technology: it can reduce energy use and allow functional features to be integrated into the material. For dental manufacturing, this could mean that form, mechanics, optics and possibly even biological properties might be designed within a single process step.

“What fascinated me from the beginning was that we could directly print and fuse a material like glass, which is generally considered difficult and fragile,” Dr Siebert said. For dental materials research and manufacturing, this approach may create new clinical and technological possibilities.