Effect of oral exposure on chemical, physical, mechanical, and morphologic properties of clear orthodontic aligners.

INTRODUCTION: The dental industry is heavily committed to developing more esthetic solutions for orthodontic treatments. Invisalign is a system of transparent orthodontic aligners introduced as an alternative to conventional orthodontic fittings with brackets and metal wires. This study aimed to assess the chemical, physical, mechanical and morphologic changes in these polymeric aligners after exposure to the oral environment. METHODS: Twenty-four Invisalign orthodontic aligners were equally divided into 2 groups: an in vivo aged group in which patients used aligners for 14 days and the reference group, unexposed to the oral environment. Different experimental techniques were used to study the chemical structure, the color changes and translucency, the density and subsequent volume of the aligners, mechanical properties, surface roughness, morphology and elemental composition. The data were subjected to several statistical analyses. RESULTS: Clear orthodontic aligners exhibit chemical stability but undergo a statistically significant optical change in color and translucency. There was a gradual increase in the water absorption rate and the dimensional variation of the polymer, indicating a strong correlation among these factors. The mechanical properties of the polymer showed a statistically significant decrease in its elastic modulus and hardness. There was a slight tendency toward increased surface roughness of the material, but no statistical differences were found between reference and aged groups. The surface morphology of the used aligners demonstrates microcracks, distortions and biofilm formation. CONCLUSION: Intraoral aging adversely affected the physical, mechanical, and morphologic properties of the Invisalign appliance.

Biomineralization of calcium phosphates functionalized with hydroxyapatite-binding peptide.

Functionalization of calcium phosphates with biomimetic peptides is a promising strategy to increase cellular response for bone tissue repair. In this work, biphasic calcium phosphate pellets were functionalized with the hydroxyapatite-binding peptide pVTK by dropping a suspension of the peptide on the pellet surface. The bioactivity tests were performed in vitro by using McCoy culture medium. Cytotoxicity tests were also performed to assess cell viability. The material was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy with field emission gun (FEG-SEM). The results showed that functionalization with the biomimetic peptide was most effective in inducing precipitation of bone-like apatite on the pellets surface, when compared to the control groups (two positive control groups and one negative control group). Cytotoxicity tests showed that all samples are biocompatible but the pellets with peptide showed the highest values of cell viability.

Measuring patient and carer experience related to paediatric gastrointestinal endoscopy: multicentre questionnaire study.

BACKGROUND: The Paediatric Endoscopy Global Rating Scale (P-GRS) is a quality improvement tool used in the UK. An important aspect of this includes regular surveys on the patient and/or carer's endoscopy experience. The aim of our study was to design and implement a patient/carer experience questionnaire. METHODS: This questionnaire was designed to obtain feedback on patient and/or carer satisfaction with their endoscopy experience. Question selection was based on relevant measures in the endoscopy Global Rating Scale, with input from clinical governance, Patient Advice and Liaison Service and a hospital youth forum. This was distributed to patients and/or carers in three UK paediatric endoscopy services during six surveys between 2013 and 2018. Data were then collated and analysed on Microsoft Excel for Office 365 MSO (16.0.11901.20070). RESULTS: Overall, 830 endoscopic procedures occurred during the six survey periods. 270 questionnaires were returned. Feedback from the questionnaires were mostly positive (overall satisfaction rated 'excellent' or 'good' was seen in 87% of responses) but also identified areas of improvement, such as in managing postprocedure pain and having a separate space for adolescents for preprocedure discussions. Improvements in satisfaction scores were noted in one unit over time, particularly in preprocedure preparation (from 86% to 100%), and overall satisfaction with endoscopy experience (81%-100%). CONCLUSION: All three paediatric endoscopy services found this questionnaire useful in identifying areas needing improvement and in demonstrating compliance with measures within the P-GRS quality of patient experience domain. Further work includes exploring ways to increase response rates, as well as developing age-appropriate and electronic versions.

The physical characterization of a thermoplastic polymer for endodontic obturation.

OBJECTIVE: To analyze a new endodontic sealer material commercially known as Resilon and to describe in detail the experimental techniques employed that lead to the identification of the composite material. METHODS: An extensive structural, thermal, and physical characterization was used to identify a new endodontic sealer material using the following techniques: Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) analysis, X-ray fluorescence spectrometry (XRF) technique, X-ray diffraction (XRD) measurement, thermo-gravimetric analysis (TGA) and a differential scanning calorimeter (DSC). The surface morphology was analyzed using a scanning electron microscope (SEM). RESULTS: The material was identified as a composite of polycaprolactone, which is a polymer of the polyester family and bioactive glass, which is radiopaque filler. CONCLUSIONS: The Resilon sealer material is a thermoplastic synthetic degradable polymer (polycaprolactone), it contains bioactive glass. Its properties, such as strength, modulus, shape-memory effect and biodegradability depend on the crystalline fraction, which is affected in turn by conditions of crystallization. Investigation of the crystallization kinetics of PCL is of practical significance. It is especially necessary to study its the dynamic and non-isothermal crystallization process.