# Clinical Applications of Nano-Hydroxapatite in Dentistry
## 4 Discussion
Two studies [28; 29] employed nano-HAp for ridge augmentation, where the authors observed overall dimensional stability of the grafted material, and success in implant placement. Another application of nano-HAp is as filling material for sinus lift [25; 31; 32]. Limited bone resorption with high bone density and implant stability was reported, even in cases of early loading. Although limited, the present evidence suggests a potential role of nano-HAp in sinus lift procedures. Finally, nano-HAp was employed as graft material in post-extractive alveolar sockets [30; 33; 34]. Current literature provides contrasting results, as according to [PERSON] et al. [33] in the absence of graft material the percentage of vital bone at 5 months was higher than in cases of nano-HAp or calcium sulphate application. Conversely, two studies [30; 34] reported improved alveolar socket healing following the application of nano-HAp, with a higher percentage of mineralized bone and earlier healing. Being the evidence insufficient, further research on nano-HAp in post-extractive alveolar sockets is advised. Two studies [37; 38] applied nano-HAp to the treatment of intrabony defects, and consistently reported an improvement in PPD and CAL at three months. One study [39] evaluated nano-HAp retention following root surface treatment with EDTA, and thus suggested root preparation prior to nanomaterial application. One study [40] evaluated the use of nano-HAp for implant coating, finding no difference in inflammatory parameters and immunological response compared to titanium mini-implants. The authors suggested that the nanostructure did not enhance tissue integration due to rapid degradation of nano-HAp and rapid adsorption. However, a systematic review by [PERSON] et al. [48] suggested that nano-HAp particles could enhance osteoblast proliferation, adhesion, and calcium deposition, while improving the bio-functionality of the implant. Nevertheless, the effectiveness of implant coating with nano-HAp requires further investigation. The present study has some limitations. No meta-analysis could be performed due to the extreme variability in the studies included. Quality analysis highlighted a moderate to high risk of bias, and in particular operators experience and missing data reporting were judged unclear in the majority of studies. All these limitations concur to limit the reliability of the analysis performed. Nevertheless, a growing interest towards the applications of nano-HAp can be observed, highlighting the need for further RCTs on the various applications of this nanomaterial. Conceptualization, R.I. and M.N. ; methodology, S.G.; software, S.G.; validation, F.G. and M.M. ; formal analysis, R.I., M.N. and S.G.; investigation, R.I., M.N. and S.G.; resources, M.R.G. ; data curation, R.I. and S.G.; writing--original draft preparation, R.I, S.G. and M.N. ; writing--review and editing, F.G., M.M. and M.R.G. ; visualization, M.N., F.G., M.M. and M.R.G. ; supervision, M.R.G. ; project administration, M.R.G. ; funding acquisition, M.R.G. All authors have read and agreed to the published version of the manuscript. This research received no external funding. Not applicable. Informed Consent Statement: Not applicable. Data Availability Statement: Data is contained within the article. Conflicts of Interest: The authors declare no conflict of interest.