Background The aim of this systematic review was to evaluate the effect of micro-osteoperforations (MOPs) performed with Propel and other mini-screws on the rate of tooth movement, pain/discomfort, periodontal health, anchorage loss, and root resorption in patients undergoing orthodontic retraction compared to a control group. Materials and methods PubMed, Cochrane, Web of Science, LILACS, Google Scholar, Scopus, and OpenGrey were searched without restriction. A manual search was also carried out. Only randomized clinical trials (RCT) were included. The risk of bias (RoB) was assessed using RoB 2.0 and the certainty of evidence through the GRADE tool. Results Among the twelve RCTs reviewed, five used the Propel system. Overall, the RoB was classified as low (4), moderate (5), and high (3). Two RCTs with moderate and one with a low RoB using the Propel system reported mild increases on rate of tooth movement associated with MOPs. One RCT with a moderate and another with high RoB did not find a significant effect of Propel on orthodontic movement. Regarding tooth movement, a subgroup meta-analysis found no differences between control and Propel movement (95% CI = − 0.01 to 0.75) or other mini-screws (− 0.02 to 0.31) related to rate of tooth movement per month. There was no effect of MOPs on root resorption, periodontal health, anchorage loss, and a mild effect on pain and oral health related to quality of life regardless of mini-screw type. The level of certainty was graded as low for the rate of tooth movement and pain/discomfort, as moderate for anchorage loss, and high for root resorption. Conclusion A low certainty of evidence supports that MOPs performed with Propel seem to have no significant effect on the rate of tooth movement. Moreover, this intervention does not seem to cause an increase in root resorption, periodontal heath, pain/discomfort, or anchorage loss. Thus, the Propel system does not appear to produce different results from those observed for other mini-screws.

Objectives: To identify the scientific evidence that demonstrates which of the transverse maxillary treatments has the least effect on periodontal tissues. Materials and Methods: PubMed (MEDLINE), Cochrane Library, Scopus, Web of Science, Virtual Health Library, Google Scholar, and OpenGrey were searched without restrictions. A hand search was also carried out in the reference lists of the articles selected. The related articles tool in the PubMed database was checked for each article included. Risk of bias assessment was performed using Cochrane Collaboration's Risk of Bias tool for randomized clinical trials and the ROBINS-I tool for nonrandomized studies of interventions. The GRADE tool was used to assess the quality of the evidence. Results: After examination of the full texts, three studies were finally included. Two studies used a Haas expander with different protocols, and one study used a Haas expander compared with a quad-helix appliance. These studies evaluated periodontal parameters and periodontal indices by clinical examination with a millimeter probe, and one study examined computed tomography images. After quality assessment, two studies were considered as having a “low” risk of bias. One study was scored as having a moderate risk of bias. The evidence was graded as moderate quality for alveolar bone level, tooth displacement, and inclination and very low for all other outcomes. Conclusions: There were no significant differences to enable a sound conclusion about which type of maxillary expansion has the least periodontal side effects.

OBJECTIVE: The aim of this longitudinal study, comprising young adults without orthodontic treatment, was to assess spontaneous changes in lower dental arch alignment and dimensions. METHODS: Twenty pairs of dental casts of the lower arch, obtained at different time intervals, were compared. Dental casts obtained at T1 (mean age = 20.25) and T2 (mean age = 31.2) were compared by means of paired t-test (p < 0.05). RESULTS: There was significant reduction in arch dimensions: 0.43 mm for intercanine (p = 0.0089) and intermolar (p = 0.022) widths, and 1.28 mm for diagonal arch length (p < 0.001). There was a mild increase of approximately 1 mm in the irregularity index used to assess anterior alignment (p < 0.001). However, regression analysis showed that changes in the irregularity index revealed no statistically significant association with changes in the dental arch dimensions (p > 0.05). Furthermore, incisors irregularity at T2 could not be predicted due to the severity of this variable at T1 (p = 0.5051). CONCLUSION: Findings suggest that post-growth maturation of the lower dental arch leads to a reduction of dental arch dimensions as well as to a mild, yet significant, increase in dental crowding, even in individuals without orthodontic treatment. Furthermore, dental alignment in the third decade of life cannot be predicted based on the severity of dental crowding at the end of the second decade of life.