The effectiveness of clear aligners in correcting malocclusions is closely linked to the properties of the materials used to make them. The polymers used in the manufacture of clear aligners have well-established properties. However, the process of manufacturing clear aligners, known as thermoforming, involves thermal and mechanical shocks that may alter these properties. The objective of this study was to evaluate the effects of thermoforming on the mechanical, optical, chemical, and morphological properties of sixty PET-G specimens. The study compared the thickness, weight, absorbance, chemical structure, surface roughness, elastic modulus, yield strength, and breaking load of thirty thermoformed specimens with thirty non-thermoformed specimens. The study introduces a new approach by using standardized samples to analyze both chemical and physical properties. The results showed statistically significant differences in thickness (−15%), weight (−11%), and surface roughness (+1233% in roughness average; +1129% in RMS roughness) of the material. Additionally, a correlation was found between reduction in thickness and increase in opalescence. There was no significant change in the functionality of the aligners after thermoforming, as no significant mechanical changes were found. However, the increase in surface roughness may lead to plaque and fluid accumulation and worsen the fit of the aligners.
1 August 2020 in Dental Press Journal of Orthodontics
Introduction: Anterior crossbite (AC) is defined as a reverse sagittal relationship between maxillary and mandibular incisors. According to an evidence-based orthodontic triage, the treatment need of AC is indicated if any occlusal interference is forcing the mandible towards a Class III growth pattern. Removable and fixed appliances have been suggested to correct AC. Objective: The present report aims at presenting the benefits of an alternative therapy for the early treatment of anterior crossbite using clear aligners. Methods: Two cases of anterior crossbite corrected using clear aligners in 8-years-old children are presented. Results: In both cases, AC was successfully corrected within 5 months. At the end of the treatment, overjet and overbite were corrected. No major discomfort or speech impairment was noticed by the parents. Conclusions: Due to the perceived shortcomings of alternative approaches, the use of clear aligners for correcting AC in mixed dentition should be considered as a comfortable and well tolerated appliance for young patients.
Objectives: The aim of this systematic review is to evaluate and compare the risks and benefits of germectomy and delayed removal of third molars and develop a patient management algorithm for second molar eruption in syndrome/incompliant patients. Materials and Methods: A literature search was performed in the following databases; the Cochrane Central Register of Controlled Trials (CENTRAL), PubMed, Scopus, and Web of Science. Last search was done on July 2nd, 2018 including articles published from the last 18 years. The search aimed to identify all relevant studies written in English language. Gray literature was excluded. Risk of bias was evaluated with specific predetermined criteria. This systematic literature review was reported according to the PRISMA-P statement and was registered in the PROSPERO database with the following protocol ID: 104261. Results: Literature search war performed on July 2018 and updated on February 2019. A total of 1610 articles were screened. After abstract screening and discarding duplicates, 86 full-text articles were obtained and subjected to additional evaluation. Four articles were included in the review. Three studies were considered as having a medium risk of bias and one was assessed as at high risk. Due to the heterogeneity of presenting results and a very low number of included studies a quantitative analysis was not possible. Only qualitative analysis was made. Considering the limited number of studies included and the level of risk of bias there is no sufficient evidence to state the benefits of preventive removal of impacted third molars, especially in patients with poor oral hygiene due to intellectual disability. Early germectomy represents an elective approach of pathologic alteration of tooth germ; orthodontic issues meet appropriate indication for a delayed removal. Conclusions: Given the best evidence-based information regarding patients’ medical condition, we highlight the need to provide an ethical-based comprehensive approach in the diagnostic workflow and the assessment of treatment outcome.
1 October 2018 in British Journal of Oral and Maxillofacial Surgery
The applications of computer-guided technologies for three-dimensional image analysis provide a unique opportunity to quantify the morphological dimensional changes of the face in a practical and convenient way. Symmetry of the nasolabial area is one of the main factors of facial attractiveness as well as being the main objective of the treatment of cleft lip and palate (CLP). Technological advances in computer-guided visualization modes and their applications to three-dimensional stereophotogrammetry provide more practical opportunities and alternatives for facial analysis. Each study, however, uses different protocols for the acquisition and analysis of three-dimensional images. In addition, each study identifies different anthropometric points and calculates linear and angular measurements with overlapping protocols. Therefore, it is appropriate to define a standardization of the three-dimensional analysis of CLP patients to compare the studies of different research centers. The aim of this report is to propose a protocol to standardize the acquisition and analysis of three-dimensional images to evaluate the three-dimensional changes in the nasolabial area in cleft lip and palate patients undergoing pre-surgical nasoalveolar molding (PNAM).