Aim: The aim of this systematic review and meta-analysis was to assess possible histomorphometric differences in new bone formation and in remaining graft particles when hyaluronic acid (HA) was added and mixed with graft materials in bone regeneration. Materials and methods: This review was registered at the International Prospective Register of Systematic Reviews (PROSPERO) of the National Institute of Health Research (registration number CRD42024530030). Electronic research was performed, and involved studies published up to 29 February 2024 using a specific word combination. The primary outcome was to assess possible histomorphometric differences in new bone formation and in remaining graft particles when HA was added and mixed with graft materials in bone regeneration. The search resulted in 138 potential studies. Meta-analyses were performed using the fixed and random effects model to identify significant changes in new bone formation and in the remaining graft particles. Results: After screening procedures, only three randomized controlled trials fulfilled the inclusion criteria and were selected for qualitative and quantitative analysis. The effect size of HA in the new bone formation was not statistically significant at 95% CI (Z = 1.734, p-value = 0.083, 95 % CI -,399; 6516). The effect size of HA in the remaining graft particles was not statistically significant at 95% CI (Z = −1.042, p-value = 0.297, CI -,835; 255). Conclusions: Within the limitations of the present systematic review and meta-analysis, the addition of HA to bone graft did not result in significant changes in bone regeneration procedures in terms of new bone formation and residues, even if the included studies showed encouraging and promising results.

Complete edentulous arches have been considered as one of the main limitations of intraoral scanners (IOSs). In these clinical scenarios, the accuracy of IOSs can be reduced because of several anatomical factors. To overcome these limitations, some studies have proposed several techniques to increase the accuracy of the impressions by means of various materials and instruments. The aim of this narrative review was to describe these techniques and to compare the obtained results to understand if it is currently feasible to increase the accuracy of the digital impressions of complete edentulous arches. An accurate analysis of the literature was performed using PubMed (National Library of Medicine) as well as manual searching without time and language restrictions. The results showed that there are few articles in the indexed literature on this topic, and that all are in vitro studies. Although the results of the analyzed studies were encouraging and reported useful in vitro results for artificial landmarks as well as for the use of an auxiliary geometry part related to the splinting of intraoral scan bodies (ISBs), clinical trials are needed to confirm that these techniques are feasible in daily clinical practice.

Bacterial adhesion to the surface of orthodontic materials is an important step in the formation and proliferation of plaque bacteria, which is responsible for enamel demineralization and periodontium pathologies. With the intent of investigating if adhesive resins used for bracket bonding are prone to bacteria colonization, the surface roughness of these materials has been analyzed, combining information with a novel methodology to observe the internal structures of orthodontic composites. Scanning electron microscopy, combined with focus ion bean micromachining and stylus profilometry analyses, were performed to evaluate the compositional factors that can influence specific pivotal properties facilitating the adhesion of bacteria to the surface, such as surface roughness and robustness of three orthodontic adhesive composite resins. To confirm these findings, contact angle measurements and bacteria incubation on resin slide have been performed, evaluating similarities and differences in the final achievement. In particular, the morphological features that determine an increase in the resins surface wettability and influence the bacterial adhesion are the subject of speculation. Finally, the focused ion beam technique has been proposed as a valuable tool to combine information coming from surface roughness with specific the internal structures of the polymers.