Metal ion release studies were carried out on three of the most commonly used orthodontic wires in the clinic: austenitic stainless steel, Ti-Mo, and superelastic NiTi, using three mouthwashes with different fluoride concentrations: 130, 200, and 380 ppm. Immersions were carried out in these mouthwashes at 37 °C for 1, 4, 7, and 14 days, and the ions released were determined by inductively coupled plasma-mass spectrometry (ICP-MS). All wires were observed by scanning electron microscopy (SEM). The results showed a moderate ion release in the stainless steel wires, with nickel and chromium values of 500 and 1000 ppb in the worst conditions for the wires: concentrations of 380 ppm fluoride and 14 days of immersion. However, in the Ti-Mo and NiTi alloys, an abrupt change in release was observed when the samples were immersed in 380 ppm fluoride concentrations. Titanium releases in Ti-Mo wires reached 200,000 ppb, creating numerous pits on the surface. Under the same conditions, the release of Ni and Ti ions from the superelastic wires also exceeded 220,000 ppb and 180,000 ppb, respectively. This release of ions causes variations in the chemical composition of the wires, causing the appearance of martensite plates in the austenitic matrix after 4 days of immersion. This fact causes it to lose its superelastic properties at a temperature of 37 °C. In the case of immersion in 380 ppm mouthwashes for more than 7 days, rich-nickel precipitates can be seen. These embrittle the wire and lose all tooth-correcting properties. It should be noted that the release of Ni ions can cause hypersensitivity in patients, particularly women. The results indicate that the use of mouthwashes with a high content of fluoride should not be recommended with orthodontic archwires.

Titanium mini-implants are used as anchorage for orthodontic tooth movements. However, these implants present problems due to the infection of surrounding tissues. The aim of this work was to obtain a polyethylene glycol (PEG) layer by plasma in order to achieve a bacteriostatic surface. Titanium surfaces were activated by argon plasma and, after, by PEG plasma with different powers (100, 150 and 200 W) for 30 and 60 min. The roughness was determined by white light interferometer microscopy and the wettability was determined by the contact angle technique. Surface chemical compositions were characterized by X-ray photoelectron spectroscopy (XPS) and cytocompatibility and cell adhesion studies were performed with fibroblast (hFFs) and osteoblast (SAOS-2) cells. Bacterial cultures with Spectrococcus Sanguinis and Lactobacillus Salivarius were performed, and bacterial colonization was determined. The results showed that plasma treatments do not affect the roughness. Plasma makes the surfaces more hydrophilic by decreasing the contact angles from 64.2° for titanium to 5.2° for argon-activated titanium, with values ranging from 12° to 25° for the different PEG treatments. The plasma has two effects: the cleaning of the surface and the formation of the PEG layer. The biocompatibility results were, for all cases, higher than 80%. The polymerization treatment with PEG reduced the adhesion of hFFs from 7000 to 6000 and, for SAOS-2, from 14,000 to 6500, for pure titanium and those treated with PEG, respectively. Bacterial adhesion was also reduced from 600 to 300 CFU/mm² for Spetrococcuns Sanguinis and from 10,000 to 900 CFU/mm² for Lactobacillus Salivarius. The best bacteriostatic treatment corresponded to PEG at 100 W and 30 s. As a consequence, the PEG coating would significantly prevent the formation of bacterial biofilm on the surface of titanium mini-implants.

Invisible orthodontic aligners are having a great impact on tooth movement in an aesthetic and effective way. Different techniques, models, and clinical aspects have been studied for their proper use. However, the aim of this research has been to determine the effect of the shaping process on mechanical properties and their bacterial behavior. For this study, 40 original polyurethane plates and 40 identical models, obtained by hot forming the original plates, were used. The static tensile mechanical properties were studied with a Zwick testing machine using testing speeds of 5 mm/min at a temperature of 37 °C. The original plate and the aligner have been studied with a creep test by subjecting the samples to a constant tension of 30 N, and determining the elongation using a long-distance, high-resolution microscope at different time periods between 1 and 720 h. Studies of water absorption has been realized with artificial saliva for 5 h. Bacterial cultures of Streptococcus oralis and Actinomyces viscosus strains were grown on the original plates and on new and used models, to determine the proliferation of each bacterium through metabolic activity, colony-forming units, and LIVE/DEAD assays. The mechanical results showed an increase in the strength of the inserts with respect to the models obtained from 3.44 to 3.95 MPa in the elastic limit and a lower deformation capacity. It has been proven that the transition zone in the creep curves lasts longer in the original plate, producing the rapid increase in deformation at a shorter time (400 h) in the aligner. Therefore, the shaping process reduces the time of dental correction exerted by the aligner. The results of the bacterial culture assays show an increase in the number of bacterial colonies when the aligners have been used and when the polyurethane is conformed due to the internal energy of the model, with respect to the original polyurethane. It has been observed that between the original plate and the aligner there are no statistically significant differences in water absorption and therefore the forming process does not affect water absorption. A slight increase in water absorption can be observed, but after five hours of exposure, the increase is very small.

Background and objectives: The interest in studying the relationship between bruxism and sleep apnea has increased over the past decade, given its prevalence and its implications for both oral and overall health. Bruxism occurs in a significant portion of the population, with an overall incidence ranging between 8 and 31%. Obstructive sleep apnea affects 4–6% of middle-aged men and 2–4% of middle-aged women, and it is associated with diminished quality of life, hypertension, increased cardiovascular risks, traffic accidents, and a higher mortality rate. Although a possible association has been suggested, the causal relationship remains unclear. This review aimed to systematically evaluate the available evidence on the association between SB and OSA, focusing on potential shared risk factors and underlying mechanisms. Methods: An electronic literature search was conducted in PubMed, Scopus, Web of Science, and the Cochrane Library for studies published between 2020 and 2025. Inclusion criteria encompassed observational studies and clinical trials involving adults with SB and/or OSA. Risk of bias was assessed using ROBINS-I, and the certainty of evidence was evaluated using GRADE. The review protocol was not registered. Results: A total of 11 studies met the inclusion criteria. The prevalence of SB was consistently higher in individuals with OSA compared to the general population. Several studies suggest a potential link through autonomic arousals and neurotransmitter dysregulation. However, inconsistencies in diagnostic criteria and moderate methodological quality limited the strength of the findings. Conclusions: There is a notable prevalence of bruxism in patients with OSA, suggesting possible shared pathophysiological mechanisms; however, it is necessary to standardize diagnostic criteria and conduct larger, more standardized studies to clarify the relationship. No funding was received, and the authors declare no conflicts of interest.

Orthognathic surgery is essential for correcting certain malocclusions and enhancing facial aesthetics. However, determining the ideal positioning of facial structures remains a topic of debate. This study aims to propose numerical references for surgical planning by determining the optimal sagittal projection of the maxillary incisors in aesthetically attractive Caucasian patients. An observational and retrospective study was conducted using cephalometric and photographic records of 89 patients' lateral profiles. These images were evaluated on a 10-point scale by orthodontists, maxillofacial surgeons, and laypeople. Cephalometric parameters were measured, including the position of the upper incisor and soft tissue pogonion, using the Barcelona Line and true vertical lines from subnasale. Statistical analyses were applied to explore the relationship between these parameters and aesthetic perception. The upper incisor and soft pogonion positions were found to significantly influence aesthetic perception. Ideal projection values for the upper incisor were 2.38 mm anterior to the Barcelona Line. The ideal projection for the soft pogonion was 6.02 mm anterior to the same reference. The positions of the upper incisor and soft pogonion are key predictors of aesthetic perception in orthognathic surgery. These findings may enhance surgical planning, although other factors may also affect facial aesthetics.