## 4 Discussion
The findings from various studies indicate that current sandblasting and acid-etching techniques are effective in maintaining implant biocompatibility [31; 32; 33; 34]. However, the potential benefits observed in some studies suggest that residual Al particles might enhance specific biological responses, such as bone growth and antibacterial properties, as shown in this review. This systematic review has several notable strengths. It comprehensively covered all the experimental studies on animals evaluating the biological effects of residual Al particles on dental implants. Furthermore, it critically evaluated the methodologies and findings of included studies, identifying both the benefits and potential concerns associated with residual Al particles on implant surfaces. Additionally, the review highlighted areas where further research is needed, guiding future studies to address unresolved questions and improve the understanding of implant surface modifications. The scarcity of evidence on the biological effects of residual alumina particles on dental implant surfaces in humans is a significant limitation in the current literature. This gap is primarily due to the ethical and practical challenges associated with conducting invasive histological assessments in human subjects. Such procedures are not feasible for routine clinical practice, as they would require biopsy or explantation of implants, which are invasive and carry potential risks for the patients. Consequently, animal experimental in vivo studies have been deemed appropriate and necessary to explore these biological effects. These studies provide valuable insights into the osseointegration process, biocompatibility, and cellular responses, which can be extrapolated to human scenarios with caution. The controlled environment of animal studies allows for precise manipulation of variables and thorough histological examination, offering a deeper understanding of the interactions between residual alumina particles and biological tissues. However, this review also has limitations. The included studies varied significantly in design, methodologies, and outcome measures, which can make it challenging to draw definitive conclusions. Differences in the sandblasting and acid-etching protocols used across studies can influence the results, making it difficult to generalize findings to all types of dental implants. Studies comparing different implant brands using different protocols for sandblasting and acid-etching the implant surface showed wide variability in surface cleanliness, with potential different biological responses of tissues to implant insertion [35; 36]. Additionally, there was a relatively small sample size of experimental animals involved in directly investigating the effects of residual Al particles across all studies. Despite a comprehensive search strategy, there is always a risk of selection bias. The diversity in outcome measures and uncontrolled confounding factors in many studies further complicates direct comparisons and interpretations of the results. Therefore, future research should address these limitations through standardized methodologies and long-term human studies to fully elucidate the impact of residual Al particles on dental implant success and patient health. Future studies should focus on long-term in vivo studies to assess the chronic effects of residual Al particles, comparative studies involving a broader range of alternative blasting materials, and finally, investigations into the molecular mechanisms underlying the observed benefits of residual Al particles. Additionally, establishing standardized protocols for assessing and controlling surface contamination during implant manufacturing would be beneficial.