# Phase Transition and Controlled Zirconia Implant Patterning Using Laser-Induced Shockwaves
## 4 Discussion  
The results of this study demonstrate the effectiveness of laser-assisted template imprinting in enhancing the osseointegration of zirconia implants. The phase transition analysis highlighted the critical role of sintering temperature and cooling rates in achieving a stabilized tetragonal phase, essential for the implants' mechanical properties and biocompatibility [50,51]. By stabilizing tetragonal zirconia before the imprint patterning, we were able to avoid the issues with phase degradation reported in other studies, such as femtosecond LIPSS [52].  
Our findings revealed that green body zirconia offered the best balance between imprint precision and pattern retention during laser patterning, addressing the reported issues of low fidelity observed in fully sintered zirconia due to its surface brittleness and hardness [53]. The transition from graphite to aluminum as a sacrificial layer significantly improved pattern quality, making it suitable for sensitive applications like medical implants.  
Furthermore, protein adsorption studies confirmed a direct correlation between increased surface pattern coverage and enhanced bioactivity, as evidenced by the notable 92% increase in protein adsorption for a patterned surface compared to the unpatterned control. The increase in protein adsorption for the patterned area aligns with the finding from studies on LIPSS patterning and sandblasting [46]. Beyond the primary outcomes, the study revealed several secondary insights. The combination of SEM and AFM analyses validated the precision and depth of the patterns achieved through laser-assisted template imprinting, which were superior to other techniques like direct laser interference patterning and nanosecond laser-induced periodic surface structuring [44,45]. These deeper and more intricate patterns are critical for promoting better osseointegration and mechanical stability by providing enhanced surface area and interlocking capabilities. Additionally, the hydrophobicity measurements aligned with the phase transition observations, illustrating improved wettability with surface modifications. These findings align with the existing research that shows wettability to improve protein interaction and osteoblast activity [51]. The comparison of sacrificial layers also provided valuable information on optimizing the imprinting process for different applications.  
The findings of this study align with and extend previous research on surface modifications to enhance the bioactivity of zirconia implants. While earlier studies have explored techniques like direct laser interference patterning and femtosecond laser irradiation, our approach of laser-assisted template imprinting offers a more precise and reproducible method for achieving intricate patterns. Unlike traditional methods, our use of a confined plasma environment and optimized sacrificial layers significantly improves the quality and fidelity of the imprints. These advancements directly contribute to the growing body of  
Figure 5: BSA absorbance as a function of time at 562 nm.  
literature supporting the use of surface patterning as a strategy to enhance osseointegration and biocompatibility in zirconia implants.  
Despite these promising results, the study has certain limitations that warrant consideration. The research focused on in vitro analyses, and the findings must be validated through in vivo studies to confirm their clinical relevance. Additionally, while the protein adsorption experiments provided indirect evidence of enhanced osseointegration, direct measurements, such as bone-to-implant contact analysis, are needed for a comprehensive evaluation. Future research should also explore the long-term stability of the imprinted patterns under physiological conditions and investigate the scalability of the laser-assisted template imprinting technique for commercial applications. Lastly, expanding the study to include different zirconia compositions and implant geometries could provide further insights into the generalizability of the findings.