Mixed reality-based technology to visualize and facilitate treatment planning of impacted teeth: Proof of concept.

OBJECTIVE: We propose a method utilizing mixed reality (MR) goggles (HoloLens 2, Microsoft) to facilitate impacted canine alignment, as planning the traction direction and force delivery could benefit from 3D data visualization using mixed reality (MR). METHODS: Cone-beam CT scans featuring isometric resolution and low noise-to-signal ratio were semi-automatically segmented in Inobitec software. The exported 3D mesh (OBJ file) was then optimized for the HoloLens 2. Using the Unreal Engine environment, we developed an application for the HoloLens 2, implementing HoloLens SDK and UX Tools. Adjustable pointers were added for planning attachment placement, traction direction, and point of force application. The visualization was presented to participants of a course on impacted teeth treatment, followed by a 10-question survey addressing potential advantages (5-point scale: 1 = totally agree, 5 = totally disagree). RESULTS: Out of 38 respondents, 44.7% were orthodontists, 34.2% dentists, 15.8% dental students, and 5.3% dental technicians. Most respondents (44.7%) were between 35 and 44 years old, and only 1 (2.6%) respondent was 55-64 years old. Median answers for six questions were 'totally agree' (25th percentile 1, 75th percentile 2) and for four questions 'agree' (25th percentile 1, 75th percentile 2). No correlation was found between age, profession, and responses. CONCLUSION: Our method generated substantial interest among clinicians. The initial responses affirm the potential benefits, supporting the continued exploration of MR-based techniques for the treatment of impacted teeth. However, the recommendation for widespread use awaits validation through clinical trials.

Hydrodynamic disintegration of thickened excess sludge and maize silage to intensify methane production: Energy effect and impact on microbial communities.

The aim of this project was to study the combination of two methods to increase methane production: feedstock pretreatment by hydrodynamic disintegration and co-digestion of maize silage (MS) with thickened excess sludge (TES). Disintegration of TES alone resulted in a 15% increase in specific methane production from 0.192 Nml/gVS (TES + MS) to 0.220 Nml/gVS (pretreated TES + MS). The energy balance revealed additional energy (0.14 Wh) would cover only the energy expenditure for the mechanical pretreatment and would not allow for net energy profit. Identification of the methanogenic consortia by 16S rRNA gene amplicon sequencing revealed that Chloroflexi, Bacteroidota, Firmicutes, Proteobacteria and Actinobacteriota were five most abundant bacteria phyla, with Methanothrix and Methanolinea as the dominant methanogens. Principal component analysis did not show any effect of feedstock pretreatment on methanogenic consortia. Instead, the composition of inoculum was the decisive factor in shaping the microbial community structure.

Re-flocculation reduces the effectiveness of sewage sludge pretreatment through hydrodynamic disintegration prior to anaerobic digestion.

Circular economy model, based on the "make, use, reuse, remake, recycle" approach, is an alternative to progressive depletion of non-renewable fossil fuels. Sewage sludge can be a source of renewable energy obtained through the anaerobic conversion of their organic fraction into biogas. This process is mediated by highly complex microbial communities and its efficiency depends on the availability of substrates to microorganisms. Disintegration of the feedstock in the pre-treatment step may intensify the anaerobic digestion, but re-flocculation of disintegrated sludge (reassembly of the released fractions into larger agglomerates) may result in a reduced availability of the released organic compounds for microbes. Pilot-scale studies on re-flocculation of disintegrated sludge were conducted to select parameters for scaling-up the pre-treatment and intensifying the anaerobic digestion process in two large Polish wastewater treatment plants (WWTPs). Samples of thickened excess sludge from full-scale WWTPs were subjected to hydrodynamic disintegration at three energy density levels of 10 kJ/L, 35 kJ/L and 70 kJ/L. Microscopic analyses of disintegrated sludge samples were carried out twice: i) immediately after the disintegration process at a given energy density level, ii) and after 24-h incubation at 4 °C following the disintegration. Micro-photographs of 30 randomly selected fields of view were taken for each analysed sample. A method of the image analysis was developed as a tool to measure dispersion of sludge flocs to assess the re-flocculation degree. Re-flocculation of the thickened excess sludge occurred within 24 h after hydrodynamic disintegration. This was evidenced by a very high re-flocculation degree, reaching up to 86%, depending on the origin of the sludge and the energy density levels used for the hydrodynamic disintegration.

[Revision of dentistry safety guidelines during COVID-19 pandemic]. / Zasady bezpieczenstwa przy udzielaniu swiadczen stomatologicznych w trakcie pandemii COVID-19.

The ongoing pandemic of coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has completely transformed the functioning of health care facilities. These changes have also significantly affected the work of dental health professionals. Due to the high infectivity of the virus and the fact that transmission occurs primarily through respiratory droplets, both dental patients and professionals are particularly exposed to coronavirus infection. In order to reduce the risk of COVID-19 transmission, a number of medical societies have issued recommendations for the provision of health care services during the pandemic. The article is based mainly on the recommendations of the Polish Ministry of Health, since WHO recommendations underline that following updated local guidelines is of highest importance. It is impossible to outline uniform guidelines for all dental specialists in the world, as the pandemic develops at differing rates in different countries and each country requires guidelines adapted to the current local epidemiological situation. The publication features an additional review of foreign literature and guidelines proposed by individual dental societies. The article presents an overview of guidelines related to the functioning of dental offices, dental treatment procedures and recommended personal protective equipment, as well as underlines the overriding principle that both physicians and dental practitioners should first and foremost take care of their own health in order to be able to protect others. Med Pr. 2021;72(5):561-8.

How to assess the efficiency of the agro waste disintegration process.

The objective of the study was to verify whether the method of determining the efficiency of sewage sludge disintegration, i.e. the disintegration degree (DD), can also be used to assess agro-waste disintegration. The following types of agro waste were tested: remains of fruits, sugar beet pulp and sugar beet pulp in the form of pellets. It was shown that DD as used for sewage sludge can also be a useful tool in assessing the disintegration efficiency of agro waste, although it requires the following modifications: (a) a methodology of chemical hydrolysis for each type of agro waste in order to determine the total amount of soluble COD (SCOD) that can be released from the sample and (b) possible changes in the SCOD value that may occur in the sample left in ambient conditions for a time period corresponding to the duration of the disintegration process. DD of agro waste determined according to the formula adopted for sewage sludge resulted in a considerable overestimation of the value in comparison to the formula proposed by the authors, i.e. DD determined for an energy density of 35 kJ L-1 was higher by 55.9 ± 21.5%, and for an energy density of 140 kJ L-1 it was higher by as much as 73.8 ± 28.1%. Taking into account the differences in the determined disintegration degree values that result from the methodology of conducting the chemical hydrolysis, it is recommended, in order to assess the efficiency of disintegration of agro waste, to use the efficiency of organic compound release.

Effect of hydrodynamic disintegration on the solubilisation and bioavailability of thickened excess sludge.

The main objective of the study was the verification whether conducting the hydrodynamic disintegration (HD) of thickened excess sludge (TES) before the anaerobic hydrolysis (AH) can cause an increase in the efficiency of the hydrolysis process, and therefore a reduction in its duration, or allow for complete omission of the stage before the anaerobic digestion (AD). For this purpose, the HD (conducted in five levels of energy density (EL): 140, 280, 420, 560 and 700 kJ/L) of TES was carried out, and then all sludges (before and after disintegration) were subjected to the AH. The obtained results confirmed that the process of HD can be an effective method of increasing the solubilisation and bioavailability of TES. In the process of HD, the maximum increase in ΔVFA (308-428 mg VFA/L), was reported when EL was increased from 140 to 280 kJ/L (the solubilisation degree increased from approximately 2 to 8%). The obtained results also showed that the ΔSTN and ΔSTP were related to solubilisation degree. The most intensive increase in the ΔSTN was determined for solubilisation degree in a range of 15-20%. In the case of ΔSTP, constant intensity of release of the compounds to the sludge liquid was observed. The obtained results also confirmed that conducting the process of AH of disintegrated TES proved to change the SCOD value when contrasted with the value of this indicator at the start of the experiment (before hydrolysis): (i) the EL equal to 140 and 280 kJ/L allowed for a higher SCOD value; (ii) at EL higher or equal to 560 kJ/L it caused a decrease in the SCOD value.