Particulate matter in aerosols produced by two last generation electronic cigarettes: a comparison in a real-world environment.

The design of e-cigarettes (e-cigs) is constantly evolving and the latest models can aerosolize using high-power sub-ohm resistance and hence may produce specific particle concentrations. The aim of this study was to evaluate the aerosol characteristics generated by two different types of electronic cigarette in real-world conditions, such as a sitting room or a small office, in number of particles (particles/cm3). We compared the real time and time-integrated measurements of the aerosol generated by the e-cigarette types Just Fog and JUUL. Real time (10s average) number of particles (particles/cm3) in 8 different aerodynamic sizes was measured using an optical particle counter (OPC) model Profiler 212-2. Tests were conducted with and without a Heating, Ventilating Air Conditioning System (HVACS) in operation, in order to evaluate the efficiency of air filtration. During the vaping sessions the OPC recorded quite significant increases in number of particles/cm3. The JUUL e-cig produced significantly lower emissions than Just Fog with and without the HVACS in operation. The study demonstrates the rapid volatility or change from liquid or semi-liquid to gaseous status of the e-cig aerosols, with half-life in the order of a few seconds (min. 4.6, max 23.9), even without the HVACS in operation. The e-cig aerosol generated by the JUUL proved significantly lower than that generated by the Just Fog, but this reduction may not be sufficient to eliminate or consistently reduce the health risk for vulnerable non e-cig users exposed to it.

Comparison of observer reliability of three-dimensional cephalometric landmark identification on subject images from Galileos and i-CAT cone beam CT.

OBJECTIVES: Recently, there has been increasing interest in the use of cone beam CT (CBCT) for three-dimensional cephalometric analysis and craniofacial reconstruction in orthodontic and orthognathic surgical treatment planning. However, there is a need to redefine the cephalometric landmarks in three dimensional cephalometric analysis and to demonstrate the reproducibility of landmark identification on the type of CBCT machine being used. METHODS: CBCT images of 20 subjects aged 15-25 years were selected, ten each from Galileos(®) (Sirona Dental Systems Inc., Bensheim, Germany) and Next Generation i-CAT(®) (Imaging Sciences International, Hatfield, PA). 2 observers located 18 landmarks on each subject twice using Dolphin-3D v. 11 software (Dolphin Imaging and Management Systems, Chatsworth, CA). Inter- and intraobserver reliability was assessed using Euclidean distances and linear mixed models. RESULTS: Overall, the intra- and interobserver reliability was excellent for both machines. The landmarks Gonion, Nasion, Orbitale and Anterior Nasal Spine (ANS) showed the greatest median Euclidean distances for both intra- and interobserver measurements. There were significant observer effects in the unified models for Sella, Menton and all six dental landmarks. For Sella, the distances between the measures were significantly smaller (more closely spaced) on the i-CAT machine than on the Galileos in both intra- and interobserver measurements. CONCLUSIONS: The intra- and interobserver reliability was excellent for both machines. Some of the landmarks were not as reproducible as others. Which machine produced the highest reliability depended on the landmark considered.

Accuracy of linear measurement in the Galileos cone beam computed tomography under simulated clinical conditions.

OBJECTIVES: The aim of this study was to determine the geometric accuracy of cone beam CT (CBCT)-based linear measurements of bone height obtained with the Galileos CBCT (Sirona Dental Systems Inc., Bensheim, Hessen, Germany) in the presence of soft tissues. METHODS: Six embalmed cadaver heads were imaged with the Galileos CBCT unit subsequent to placement of radiopaque fiduciary markers over the buccal and lingual cortical plates. Electronic linear measurements of bone height were obtained using the Sirona software. Physical measurements were obtained with digital calipers at the same location. This distance was compared on all six specimens bilaterally to determine accuracy of the image measurements. RESULTS: The findings showed no statistically significant difference between the imaging and physical measurements (P > 0.05) as determined by a paired sample t-test. The intraclass correlation was used to measure the intrarater reliability of repeated measures and there was no statistically significant difference between measurements performed at the same location (P > 0.05). CONCLUSIONS: The Galileos CBCT image-based linear measurement between anatomical structures within the mandible in the presence of soft tissues is sufficiently accurate for clinical use.

The status of oral and maxillofacial radiology worldwide in 2007.

The status of oral and maxillofacial radiology in other countries is often of importance when making an application for specialty recognition. This information has not previously been readily available. This paper presents the results of a survey to determine the status of oral and maxillofacial radiology worldwide in 2007.

Real-time measurement of particulate matter deposition in the lung.

Air pollution and cigarette smoke are recognized health risks. A method was developed for the measurement of the deposition fraction (DF) of polydisperse particulate matter (PM) in human airways. Ten normal volunteers [three females, age range 18-67 years, mean age (SD) 43.9 (14)] made single breath exhalations after inhalation to total lung capacity. The exhaled breath was diverted to a multichannel laser diffraction chamber where the particulate profiler measured 0.3 - 1.0-microm particles. DF was inversely related to expiration flow-rate, 0.69 (0.02) at 4 l min-1 and 0.5 (0.01) at 13 l min-1, respectively (p<0.05), and was influenced by the inhalation flow-rate [0.70 (0.02) at 3 l min-1 and 0.59 (0.02) at 13 l min-1, respectively (p<0.05)], while no differences were found between nasal and oral inhalation (0.68 (0.05) versus 0.67 (0.06), p>0.05). Higher breath holding times were associated with elevated DF [0.74 (0.02) at 20 s, and 0.62 (0.05) without breath holding (p<0.01)]. When the expiratory flow was controlled and the breath hold time standardized, DF was reproducible (CV = 4.85%). PM can be measured in the exhaled breath and its DF can be quantified using a portable device. These methods may be useful in studies investigating the health effects of air pollution and tobacco smoke.

Spontaneous regression of a large radiolucent lesion in the mandible.

This report presents a case of a large radiolucent lesion in the left posterior area of the mandible, causing displacement and resorption in the roots of a molar and enlargement of the body and ramus. Three years later, the lesion had undergone spontaneous regression without treatment. The radiological features and differential interpretation, as well as a discussion of the possible mechanism for the spontaneous regression are presented.

Chromatic confocal microscopy with a finite pinhole size.

Chromatic confocal microscopy has the advantage of short measurement times because of its parallel depth scan. As most white-light sources have limited optical output power, light-efficient setups are necessary. Using an extended detection pinhole is one way to improve light efficiency. We have calculated the effect of extended pinholes in chromatic confocal setups. We found that, for certain pinhole sizes, the FWHM of the confocal signal is nearly constant over a large wavelength interval.

Particulate matter from tobacco versus diesel car exhaust: an educational perspective.

BACKGROUND: Air pollution is a common alibi used by adolescents taking up smoking and by smokers uncertain about quitting. However, environmental tobacco smoke (ETS) causes fine particulate matter (PM) indoor pollution exceeding outdoor limits, while new engines and fuels have reduced particulate emissions by cars. Data comparing PM emission from ETS and a recently released diesel car are presented. METHODS: A 60 m3 garage was chosen to assess PM emission from three smouldering cigarettes (lit sequentially for 30 minutes) and from a TDCi 2000cc, idling for 30 minutes. RESULTS: Particulate was measured with a portable analyser with readings every two minutes. Background PM10, PM2.5, and PM1 levels (mean (SD)) were 15 (1), 13 (0.7), and 7 (0.6) microg/m3 in the car experiment and 36 (2), 28 (1), and 14 (0.8) microg/m3 in the ETS experiment, respectively. Mean (SD) PM recorded in the first hour after starting the engine were 44 (9), 31 (5), and 13 (1) microg/m3, while mean PM in the first hour after lighting cigarettes were 343 (192), 319 (178), and 168 (92) microg/m3 for PM(10), PM2.5, and PM1, respectively (p < 0.001, background corrected). CONCLUSIONS: ETS is a major source of PM pollution, contributing to indoor PM concentrations up to 10-fold those emitted from an idling ecodiesel engine. Besides its educational usefulness, this knowledge should also be considered from an ecological perspective.

The three-dimensional microstructure of the trabecular bone in the mandible.

This study investigated the three dimensional (3D) trabecular microstructure of the alveolar and basal bone in the mandible using micro-CT and compared the morphometric values of the different sites. Ten specimens were prepared and scanned using a micro-CT system. Both the alveolar and basal trabecular bone of the premolar region in the mandible were measured for the structural analysis. Cross-sectional 1024x1024 pixel images were created. From the two-dimensional (2D) images produced, 3D structural images were reconstructed. After scanning the specimen, the volumes of interest (VOI) of the alveolar and basal bone regions were selected from the 3D reconstruction images, and the structural parameters such as bone volume fraction, bone surface density, trabecular thickness, trabecular separation, trabecular number and structural model index were analyzed. The trabecular structure showed a marked variation within the sites of the specimen, especially in the basal trabecular bone inferior to the mandibular canal. In both the alveolar and basal bone regions, a mixture of both plate-like and rod-like structures was observed. The alveolar region showed a more compact, plate-type trabecular structure than the basal regions. In parametric comparison with the basal bone, the alveolar bone generally had a higher bone volume fraction, bone trabecular thickness and trabecular number, and lower bone surface density, trabecular separation and structural model index. The alveolar bone consisted of a compact bone structure with a large amount of thick plate-type trabecular bone, which was effectively resistant to the masticatory forces. As the measurements were made closer to the basal bone, a loose structure was observed with lower bone volume and fewer, thin, rod-like trabeculae.

Indoor particulate matter measurement as a tool in the process of the implementation of smoke-free hospitals.

AIM OF THE STUDY: There are International and National standards that requires hospitals and health premises to be smoke-free. According to recent data from Italy and other European Countries, smoking is a widespread habit in hospitals. To get smoke-free hospitals in an Italian region, we have adopted the European Code for smoke-free hospitals, which sets standards and provides instruments for its implementation. According to the Code, whenever possible, each step towards a smoke-free hospital, should be shared by all staff. As a mean for achieving this goal, in our region the certification of single units as smoke-free units has been chosen. For getting the certification, besides implementing the Code, we planned to use ETS (Environmental Tobacco Smoke) monitoring, as ETS should not be present in hospitals. As a marker of ETS we have chosen Particulate Matter (PM), as it can easily be measured in real-time with a portable instrument and, when other even outdoor--sources of combustion can be ruled out, it is an accurate detector of cigarette smoke. Here the first experience of measuring PM in hospitals for monitoring ETS and certificating smoke-free health premises, is described. MATERIALS AND METHODS: PM measurements were carried out without any previous notification in different areas of two Network hospitals of the Veneto Region, during a single working day. A real time laser-operated aerosol mass analyser was used. Several classes of PM (PM1, PM2.5, PM7, PM10, TSP Total Suspended Particles) were measured. RESULTS: Outdoor PM levels were found to be repeatedly lower than the annual official limits of 65 mcg/m3 and around the 24 hour official limits of 15 mcg/m3 [15 to 20 mcg/m3, with an overall mean (+/-SD) of 17.8 (1.9)] throughout the whole day. Very good indoor air quality was found in the operating theaters and isolation department, where PM2.5 concentrations were much lower than outdoor levels [1.6 (0.9) and 5.9 (0.6) mcg/m3, respectively]. No increase in PM pollution was found in the surveyed medical offices, halls and waiting rooms where smoking was positively forbidden [PM2.5 concentrations of 14.8 (2.2) and 12.9 (1.1) mcg/m3] except in a medical office and in two coffee rooms for staff only where high PM levels were recorded [PM2.5 58.7 (29.1), 27.0 (10.6) and 107.1 (47.8) mcg/m3] and an offence of smoking restrictions could be proved. CONCLUSIONS: The measurement of PM in hospital for monitoring ETS proved to be both feasible and sensible. PM measurements with a portable instrument can be used both for controlling the compliance with rules or chosen standards and for educating staff about smoking related hazards, thus gaining consensus for the implementation of the tobacco control policy. In our experience, PM measurement can be used as an aid inside all actions designed by the European Code for smoke-free hospitals.

Signal evaluation for high-speed confocal measurements.

The confocal-detection principle is open especially for use in medical applications. For inspection systems applications for technical objects in reflection confocal setups are of growing importance. For such applications the confocal measurements need to have a very short measuring time. A fast detection system is needed and to satisfy this requirement only a small number of height levels are measured and a fast-evaluation algorithm is used. Drawbacks of the reduction of height levels are a greater influence of noise and additional systematic errors on the measured heights. Study the effects of the reduction are calculated, different evaluation algorithms are analyzed, and the optimization of the parameters is discussed.

A new device for measuring density of jaw bones.

OBJECTIVES: The purpose of this project was to develop a lightweight, simple device to evaluate alveolar process bone density using normal intraoral and extraoral imaging procedures. METHODS: A simple lightweight device was constructed using barium sulfate as the major radiopaque component. The 5 x 32 x 12 mm(3) resin block has eight segments with known densities ranging from 1.304 (g/cm(3)) to 1.982 (g/cm(3)). The device was integrated into an XCP unit for standard intraoral radiographs and placed between the jaws for computer aided tomographic imaging. The relationship between the device segment densities and the optical densities of the exposed film was plotted. RESULTS: A linear inverse relationship was found between the device segment densities and optical densities when segment densities were between 1.304 (g/cm(3)) to 1.882 (g/cm(3)). However, the relationship was non-linear for segment densities above 1.882 (g/cm(3)). CONCLUSIONS: Normal human bone density is 1.85 (g/cm(3)), and this densitometer is useful for determination of material densities from 1.304 (g/cm(3)) to 1.882 (g/cm(3)). The device may be useful for precise bone density assessment.

3D volume rendering using multislice CT for dental implants / Volume 3D que rende usando o multifatiado CT para implantes dent[arios

To determine the precision and accuracy of three-dimensional (3D) volume rendering spiral multislice computed tomography (CT)-based linear measurements of the mental foramen for dental implants, in vitro, and their precision, in vivo. Methods: Five cadaver heads were imaged by multislice spiral CT (Toshiba Aquilion) with 0.5mm thick axial slices (0.5 mm0.5 s of table feed) at 0.5 mm interval reconstructions. The image data sets were transferred to a networked computer workstation. Using computer graphics the data were analysed with a 3D volume rendering technique using Vitrea software. Two oral and maxillofacial radiologists, independently, made eletronic linear measurements from the superior border of the mental foramen to the crest of the alveolar process. The soft tissues were removed and physical measurements made using a 3 [Space POT. TM[ (Polhemus, Colchester, VT, USA) electromagnetic digitizer with a personal computer running Windows 98. The same linear measurements of 15 patients using the same imaging methodology were performed and the precision was analysed. Results: The findings showed no statistically significant inter- or intra-observer differences in vitro and in vivo, or between imaging and physical measurements in vitro (P > 0.05). Conclusions: 3D multislice spiral CT imaging allows highly accurate measurements for dental implant placement in proximity to the mental foramen. Computer graphics software, using volume rendering is suitable for implant planning

3D volume rendering using multislice CT for dental implants.

OBJECTIVES: To determine the precision and accuracy of three-dimensional (3D) volume rendering spiral multislice computed tomography (CT)-based linear measurements of the mental foramen for dental implants, in vitro, and their precision, in vivo. METHODS: Five cadaver heads were imaged by multislice spiral CT (Toshiba Aquilion) with 0.5 mm thick axial slices (0.5 mm/0.5 s of table feed) at 0.5 mm interval reconstructions. The image data sets were transferred to a networked computer workstation. Using computer graphics the data were analysed with a 3D volume rendering technique using Vitrea software. Two oral and maxillofacial radiologists, independently, made electronic linear measurements from the superior border of the mental foramen to the crest of the alveolar process. The soft tissues were removed and physical measurements made using a 3 Space (Polhemus, Colchester, VT, USA) electromagnetic digitizer with a personal computer running Windows 98. The same linear measurements of 15 patients using the same imaging methodology were performed and the precision was analysed. RESULTS: The findings showed no statistically significant inter- or intra-observer differences in vitro and in vivo, or between imaging and physical measurements in vitro (P>0.05). CONCLUSIONS: 3D multislice spiral CT imaging allows highly accurate measurements for dental implant placement in proximity to the mental foramen. Computer graphics software, using volume rendering is suitable for implant planning.

Aberration measurement from confocal axial intensity response using neural network.

We propose a high-speed, parallel system for lens aberration measurement employing a confocal optical setup. This method uses a non-interferometric, conventional confocal axial response to determine the spherical aberration coefficient of a confocal objective. The aberration coefficients are successfully calculated from the intensity axial response by employing a neural network. It is estimated that the system can find out the aberration coefficients of 10,000 microlenses in 20 seconds of measurement and 1 second of calculation time. Our experimental results also demonstrate the practicality of this system.