Air-water Spray Research Articles

Desirability function based optimization of experimental data for air-water spray impingement cooling

Desirability function based optimization of experimental data for air-water spray impingement cooling

Effect of various chemical agents used in gingival retraction systems on smear layer: Scanning electron microscope study.

Background:Chemical agents used for gingival retraction affects the smear layer.Aim:To determine the effect of three different chemical agents used for gingival retraction systems on smear layer.Materials and Methods:Four human premolars were prepared using air-rotor with air-water spray to receive full crown restoration. Three of them were treated with 21.3% aluminum chloride for 10 min, 0.05% oxymetazoline hydrochloride for 10 min, and expasyl for 2 min, respectively. One sample was left untreated. Then, the tooth specimens were rinsed with tap water to remove any residue of test materials. All the samples (treated and untreated) were processed by scanning electron microscope (SEM). Processed samples were examined under SEM at ×2400 to evaluate the effect of chemical agents on smear layer.Results:SEM examination revealed that 0.05% oxymetazoline hydrochloride for 10 min produced no alteration to smear layer followed by minimum alteration by expasyl for 2 min and complete removal of smear layer with etching of dentin with 21.3% aluminum chloride for 10 min.Conclusion:0.05% oxymetazoline hydrochloride and expasyl are kind to smear layer.

Determination of heat transfer coefficients for complex spray cooling arrangements

Numerical simulation of quenching by air-water spray cooling requires an accurate knowledge of the spray heat transfer coefficients (HTCs). In this work, a novel method of heat transfer determination is presented that takes lacking aspects of prior determination methods into account. The temperature trends during cooling of a thin-walled tube are used in an optimisation calculation based on a numerical model of the setup to determine the HTCs. It is shown that higher inlet pressures lead to higher heat transfers and that the heat transfer between two spray nozzles increases with decreasing nozzle to nozzle distance. However, for some cases, adjacent sprays can lead to decreasing HTCs. The amount of nozzles in circumferential direction had an overproportioned effect on the heat transfer in the film boiling regime. Verifications generally show a good agreement of measured with computed temperature trends based on the calculated HTCs.

Laser all-ceramic crown removal and pulpal temperature--a laboratory proof-of-principle study.

The objective of this proof-of-principle laboratory pilot study was to evaluate the temperature increase in the pulp chamber in a worst case scenario during Er:YAG laser debonding of all-ceramic crowns. Twenty extracted molars were prepared to receive all-ceramic IPS E.max CAD full contour crowns. The crowns were bonded to the teeth with Ivoclar Multilink Automix. Times for laser debonding and temperature rise in the pulp chamber using micro-thermocouples were measured. The Er:YAG was used with 560mJ/pulse. The irradiation was applied at a distance of 5mm from the crown surface. Additional air-water spray for cooling was utilized. Each all-ceramic crown was successfully laser debonded with an average debonding time of 135 ± 35s. No crown fractured, and no damage to the underlying dentin was detected. The bonding cement deteriorated, but no carbonization at the dentin/cement interface occurred. The temperature rise in the pulp chamber averaged 5.4° ± 2.2°C. During 8 out of the 20 crown removals, the temperature rise exceeded 5.5°C, lasting 5 to 43s (average 18.8 ± 11.6s). A temperature rise of 11.5°C occurred only once, while seven times the temperature rise was limited to 6.8 ± 0.5°C. Temperature rises above 5.5°C occurred only when the laser was applied from one side and additional cooling from the side opposite the irradiation. Er:YAG laser energy can successfully be used to efficiently debond all-ceramic crowns from natural teeth. Temperature rises exceeding 5.5°C only occur when an additional air/water cooling from a dental syringe is inaccurately directed. To avoid possible thermal damage and to allow further heat diffusion, clinically temperature-reduced water might be applied.

A Comparison of Shear Bond Strength of Orthodontic Brackets Bonded with Four Flowable Composites Bonded under Contamination: An Ex-Vivo Study

Objective: To evaluate the shear bond strength of the brackets bonded with adhesive and flowable composites under contamination by human blood and human saliva& to evaluate enamel damage post debonding using ARI index. Material and Methods: 100 human premolars extracted for orthodontic reasons were used & shear bond strengths of 4 flowable composites and one conventional composite were evaluated under 2 bonding conditions: (1) contamination with saliva (2) contamination with blood. Contamination was done after the application of primer in all the groups and before bonding the brackets, decontamination was done by using the air water spray for 5 seconds and air drying the surface. Shear bond strengths were measured with universal testing machine after placing the bonded specimen in deionized water and incubator at 37˚C for 72 hours to permit adequate water absorption and equilibration. After debonding, each specimen was examined under a stereoscopic zoom microscope (10X) to identify the location of the bond failure. The residual composite remaining on the premolar was assessed by using the remnant index (ARI), where each specimen was scored according to the amount of material remaining on the enamel surface. Results: conventional composite showed the highest bond strength in both blood and salivary contaminations. Among the flowable composites, each behaved differently. Blood contamination showed reduced bond strengths in all the groups. Decontamination with air water spray and air drying the surface before bonding the brackets seems to be satisfactory. Conclusion: with use of a primer, flowable composites can be used to bond the orthodontic brackets under contamination and decontamination with air water spray for 5 seconds and air drying the surface before bonding seems to be satisfactory if contamination occurs after the application of the primer.

Direct measurement of time-dependent anesthetized in vivo human pulp temperature

ObjectivesHuman intrapupal tooth temperature is considered to be similar to that of the body (≈37°C), although the actual temperature has never been measured. This study evaluated the in vivo, human, basal, coronal intrapulpal temperature of anesthetized upper first premolars. MethodsAfter approval of the local Ethics Committee was obtained (protocol no. 255,945), upper right and left first premolars requiring extraction for orthodontic reasons from 8 volunteers, ranging from 12 to 30 years old, received infiltrative and intraligamental anesthesia. The teeth (n=15) were isolated using rubber dam and a small, occlusal preparation was made using high-speed handpiece, under constant air–water spray, until a minute pulp exposure was attained. The sterile probe from a wireless, NIST-traceable, temperature acquisition system (Thermes WFI) was inserted directly into the coronal pulp. Once the probe was properly positioned and stable, real-time temperature data were continuously acquired for approximately 25min. Data (°C) were subjected to 2-tailed, paired t-test (α=0.05), and the 95% confidence intervals for the initial and 25-min mean temperatures were also determined. ResultsThe initial pulp temperature value (31.8±1.5°C) was significantly lower than after 25-min (35.3±0.7°C) (p<0.05). The 95% confidence interval for the initial temperature ranged from 31.0 to 32.6°C and from 35.0 to 35.7°C after 25min. A slow, gradual temperature increase was observed after probe insertion until the pulp temperature reached a plateau, usually after 15min. SignificanceConsistent coronal, human, in vivo temperature values were observed and were slightly, but significantly below that of body core temperature.

Pulsed Light-Emitting Diode Photography for Coarse Water Characterization

An optical photography probe employing pulsed light-emitting diode (LED) illumination has been developed for application to coarse water measurement in wet steam. High image resolution (1.38 μm/pixel) and low exposure time (100 ns) photographs capture details of microdynamic flow features with reduced motion blur. Camera and lens are held inside a 50 mm O.D. cylindrical tube, with a custom designed titanium probe head allowing purging air to clear the front optical surface of stagnant liquid. Double exposure images are analyzed using standard image processing techniques to extract the size and velocity of liquid droplets. The accuracy and repeatability of the measurement probe has been verified on air–water sprays with direct comparison to phase-Doppler anemometry (PDA) measurements, which show good agreement.

Laser all-ceramic crown removal-a laboratory proof-of-principle study-phase 2 crown debonding time.

The removal of all-ceramic crowns is a time consuming procedure in the dental office. Little research has been done in alternative removal techniques for all-ceramic crowns. The objective of the second phase of this proof-of-principle laboratory pilot study was to evaluate whether Ivoclar Vivadent all-ceramic crowns can be efficiently removed from natural teeth without damage to the underlying tooth structure using an Erbium laser. The ceramic materials used were IPS E.max CAD Lithium-disilicate (LS2 ) (E.max CAD) and IPS E.max ZirCAD Zirconium-oxide (ZrO2 ) (ZirCAD) (Ivoclar, Vivadent, Liechtenstein). Molars, either as stand-alone teeth or placed in an artificial row of teeth, were prepared to receive all-ceramic crowns. Copings and full contour crowns with either featheredge or regular margins were produced. The all-ceramic crowns were bonded to the teeth with Ivoclar Multilink Automix. The time for Er:YAG laser debonding of each crown was then measured. The Er:YAG (LiteTouch, Syneron, Yokneam, Israel) was used with an 1,100 µm diameter fiber tip with energies up to 600 mJ per pulse (wavelength 2,940 nm, 10 Hz repetition rate, pulse duration 100 µs at 126 mJ/pulse, and 400 µs at 590 mJ/pulse). The irradiation was applied at a distance of 10 mm from the crown surface following a defined pattern. Air-water spray was applied to the crowns at a rate of 67 ml/minute. All of the all-ceramic crowns were successfully debonded with the laser. On average, an all-ceramic E.max CAD crown was debonded in 190 ± 92 seconds (average ± SD). The debonding time for ZirCAD featheredge crowns was 226 ± 105 seconds and for ZirCAD crowns with regular margins it was 312 ± 102 seconds. No crowns fractured and no damage to the underlying dentin was detected. The bonding cement deteriorated due to the Er:YAG irradiation. Additionally, no carbonization at the dentin/cement interface was observed. Er:YAG laser energy can successfully be used to efficiently debond all-ceramic full contour crowns from natural teeth without damage to the underlying tooth structure. Lasers Surg. Med. 46:636-643, 2014. © 2014 Wiley Periodicals, Inc.

A Comparative Evaluation of Microleakage of Glass Ionomer Restoration with Different Surface Protectors - an In-Vitro Study

Abstract Aim: All the restorative material whatsoever introduced till-date have an inherent disadvantage of micro-leakage measurable different grades. The present study comparatively evaluates the micro-leakage of glass ionomer restoration with different surface protection methods. Methodology: 36 premolars were obtained without any cracks or restorations for the study. Teeth were stored in distilled water containing thymol crystals till the beginning of the study. The teeth were randomly divided into 3 groups based on surface protectors used. Group I is GC Fuji Varnish, Group II is vaseline and Group III is G-Coat plus along with GIC restoration. Class V cavities were prepared of dimensions mesio-distal width of 3 mm, occluso-gingival length of 2 mm, and a depth of 1.5 mm on buccal and lingual surfaces with a high-speed hand-piece with air-water spray. Results: Kruskal- Wallis test was applied and Vaseline group showed significantly less micro-leakage compared to G-Coat plus i.e. G-Coat plus exhibited significantly higher microleakage compared to other groups. Conclusion: Evaluation of micro-leakage of glass ionomer cements using various surface protecting agents, Vaseline was considered the best surface protecting agent maintaining the water balance and showing no micro-leakage.

Effect of Different Base Materials and Techniques on Microleakage in Class II Composite Open Sandwich Restorations: An in vitro Study

ABSTRACT Aims This study was performed to compare microleakage in class II composite restorations with flowable composites and dual cure composite resin as intermediate material and also to evaluate the effect of delayed light polymerization of dual cure composite base on microleakage. Materials and methods Class II box cavities were made with air water spray and divided into four groups. Group 1 was restored without base, group II with flowable composite base, group III with a dual cure composite base which was immediately cured and group IV with 60 seconds delayed cure, dual cure composite base. Remaining cavity was restored with composite resin Specimens were immersed in methylene blue dye after thermocycling and sectioned through mesiodistal center of tooth and observed for leakage pattern. Microleakage was evaluated using dye penetration with methylene blue. Microleakage pattern was observed under a stereomicroscope. Kruskal-Wallis test and Mann-Whitney test were used for statistical analysis. Results Results of the study showed that application of a composite resin base below a class II composite restoration significantly decreased microleakage as compared to restorations without a base. The least and comparable microleakage scores were seen in groups with flowable composite and dual cure composite (delayed cure) as a base, followed by dual cure composite which was immediately cured. How to cite this article Bhanwal U, Nadig RR, Jagdish K, Pai V, Yashwanth. Effect of Different Base Materials and Techniques on Microleakage in Class II Composite Open Sandwich Restorations: An in vitro Study. World J Dent 2014;5(2):87-91.

Minimally invasive treatment of dental caries in primary teeth using an Er:YAG Laser.

Maintaining deciduous teeth as long as possible represents a goal in pediatric dentistry and avoids a plethora of health problems. Er:YAG carious decay treatment may help for prevention as well as during the curative processes. An Er:YAG laser was used to ablate 30 carious lesions on primary teeth. Diagnosis being conventionally dressed, treatment was conducted in respect of the following parameters: Er:YAG laser (Lite Touch, Syneron): output power from 300 mJ (enamel) to 200 mJ (dentine), frequency 20 Hz, sapphire tip (diameter 1.3 mm), air water spray ratio 8 (39 ml/min), pulse duration 50 µsec., theoretical fluence ranging from 15.08 J/cm(2) for dentin to 22.61 J/cm(2) for enamel. Then cavity depth was controlled (observation + probe). Glass-ionomer cement (GC Fuji Triage capsule) or flowable composite resin or compomer were used to fill the cavities. Children's acceptance to Er-YAG laser treatment was evaluated. According to predefined criteria, each case was followed up for one month after treatment and then with further monthly follow-ups for one year. Clinical cases illustrate the validity of this clinical approach. The benefit of laser dental treatment has been shown to be the greatest in children. However, the lack of studies evaluating laser ablation capability in primary teeth restrains the adoption of this technology. The interaction between the Er:YAG laser and primary enamel and dentin depends on the composition of the tissues - a higher presence of water and lower presence of minerals- comparative to the permanent enamel and dentin. Thus, photoablation of primary enamel and dentin requires lower energy. This study shows that the laser parameters used (300 mJ/20 Hz for enamel and 200 mJ/20 Hz for dentin) are efficient enough for the ablation of tissues of deciduous teeth and moreover demonstrates to be well accepted by young patients.

Research on On-Line Pre-Hardening Process of 718H Die Steel

New on-line pre-hardening (OPH) equipment for quenching die steel has been developed by University of Science and Technology Beijing and Dongbei Special Steel Group in Dalian Special Steel Co., LTD. OPH consists of strong cooling water jet, medium cooling water jet, weak cooling water jet, air-water spray and side water jet and has flexible cooling and control ability. Based on the equipment, online quenching process of 718H die steel was performed by numerical simulation and production experiment. The result of temperature field by numerical simulation agrees well with experiment result, which can prove that numerical simulation can be a very good guidance for production experiment. Experimental tempering metallographic structure of the whole 718H plate is tempered troostite and sorbite and the tempering hardness difference of 718H die steel can be controlled within 2 HRC in the whole plate under on-line pre-hardening process by numerical simulation. The prediction technology of numerical simulation can meet the different cooling rate control and make quenching process comply with preset quenching route to guarantee material microstructure and performance.

A report on the use of Er:YAG laser for pilot hole drilling prior to miniscrew insertion

The aim of the present in vitro study was to investigate the required time period of the Er:YAG laser that is used for drilling through cortical bone when pilot hole drilling is needed before miniscrew insertion. Even though Er:YAG laser is used in various in vivo and in vitro studies, there is no accepted procedure of laser for depth control during drilling through cortical bone. The study sample consisted of 120 cortical bone segments having 1.5 and 2.0mm of cortical bone thickness. An Er:YAG laser, with a spot size of 1.3mm and an air-water spray of 40-50ml/min, was used. The laser was held 2mm away from and perpendicular to the bone surface with different laser settings. Twelve specimens were prepared for each subgroup. As the cortical bone thickness increased, the time needed to drill through the bone increased. Frequency increase directly caused a decrease in irradiation duration. When three different frequency, three different energy, and four different power values were tested for both the 1.5- and 2-mm cortical bone thicknesses, the shortest duration needed to drill through cortical bone was seen in the 3.6-W (300mJ-12Hz) setting. When pilot holes are drilled prior to miniscrew placement in 1.5 to 2mm of cortical bone using Er:YAG laser, the most appropriate value is found with the 3.6-W (300mJ-12Hz) setting.

Numerical Simulation and Experiment on Quenching Process of P20 Die Steel with New Online Pre-Hardening Equipment

A new online pre-hardening (OPH) equipment for quenching die steel has been developed by University of Science and Technology Beijing (USTB) and Dongbei Special Steel Group in Dalian Special Steel Co., LTD. OPH equipment consists of strong cooling water jet, medium cooling water jet, weak cooling water jet, air-water spray, and side water jet and has flexible cooling and control ability. Based on the equipment, online quenching process of AISI P20 (3Cr2Mo) die steel was performed by numerical simulation and production experiment. The result of temperature field by numerical simulation agrees well with experiment result, which can prove that numerical simulation can be a very good guidance for production experiment. Experimental tempering metallographic structure of the whole P20 plate is tempered troostite and the tempering hardness difference of P20 die steel can be controlled within 3 HRC in the whole plate under quenching process by numerical simulation. The prediction technology of numerical simulation can meet the different cooling rate control and make quenching process comply with preset quenching route to guarantee material microstructure and performance.

Clinical evaluation of conventional and laser tooth preparation using visual analogue scale

Context: Use of lasers in painless contemporary restorative dentistry. Aims: To assess the extent of painless perception using lasers for tooth preparation based on visual analogue scale (VAS). To compare conventional and laser tooth preparation using VAS scale. Settings and Design: Adult patients reporting to the Department of Conservative Dentistry were selected. Fotona fidelis make for ER:YAG laser was used at preset laser settings for enamel and dentin removal with combination of air-water spray. Materials and Methods: Standardized class I tooth preparation for composite restorations were selected for individuals requiring treatment for teeth with similar enamel/dentinal configuration, that is, contralateral in the same individual. Carbide burs-SS White #245 were used for all preparations. Identical tooth preparations were carried out by the same operator for both the teeth using conventional high speed on one side and ER:YAG laser at noncontact mode on the other side. Fotona fidelis make was used at preset laser settings for enamel and dentin removal with combination of air-water spray. The patient was required to provide score according to the VAS scale. Statistical Analysis Used: Kruskal-Wallis test. Results: The median of pain while preparing tooth by conventional method is the highest in patient (8) and the smallest in ER:YAG laser (1). The P value is very small (less than the common alpha-level of 0.05), the test is significant. Thus, it is concluded that the method of tooth preparation does affect the pain perception. Conclusions: The statistical analysis of these findings comprehensively prove that laser tooth preparation is much more painless, hence comfortable for the patient, only the economics prove to be a deterrent in its widespread usage.

Testing Dust Control Preparation with Respect to Mine Employee Exposure to Inhalling Chemical Agents

Abstract This paper presents the results of tests used in dust hazard prevention for air-water spraying devices in collieries. The purpose of the tests was to evaluate mine employees’ exposure to inhalling chemical agents when the ZWILKOP ZW-10 preparation is used. The paper presents the results of the measurements of concentration, in a mine atmosphere, of the following chemical agents: hazardous substances 2-(2-butoxyethoxy)ethanol and 2-ethylhexan-1-ol, constituting ingredients of the preparation at mine employees’ workstations. The tests were performed during work related to the mining of coal in inclined drift C31, seam 415/1-2 on the premises of “Borynia-Zofiowka-Jastrzebie” Hard Coal Mine, Jastrzebie-Zdroj, Poland, using the TELESTO mist systems. Using aqueous solutions for the preparation at concentrations of 15 and 20‰ causes no exceedance of the allowable mine air concentrations for the chemical agents tested.

Morphological Changes of Human Dentin after Erbium-Doped Yttrium Aluminum Garnet (Er:YAG) and Carbon Dioxide (CO2) Laser Irradiation and Acid-etch Technique: An Scanning Electron Microscopic (SEM) Evaluation.

The aim of this study was to investigate the morphological changes of human dentin after Erbium-Doped Yttrium Aluminum Garnet (Er:YAG), Carbon Dioxide(CO2) laser-irradiation and acid-etching by means of scanning electron microscopic (SEM) Methods: 9 extracted human third molars were used in this study. The teeth were divided in three groups: first group, CO2 laser with power of 1.5 w and frequency of 80 Hz; second group, Er:YAG laser with output power of 1.5 W frequency of 10 Hz, very short pulse with water and air spray was applied; and third group, samples were prepared by acid-etching 37% for 15 sec and rinsed with air-water spray for 20 sec. Then, the samples were prepared for SEM examination. Melting and cracks can be observed in CO2 laser but in Er:YAG laser cleanedablated surfaces and exposed dentinal tubules, without smear layer was seen. It can be concluded that Er:YAG laser can be an alternative technique for surface treatment and can be considered as safe as the conventional methods. But CO2 laser has some thermal side effects which make this device unsuitable for this purpose.

Does the ultrasonic cleaning medium affect the adhesion of resin cement to feldspathic ceramic

To evaluate the effect of different cleaning media on the adhesion of resin cement to feldspathic ceramic after etching. The cementation surfaces of ceramic blocks (N = 20, n = 5 per group) were etched with 10% hydrofluoric acid (HF) gel for 20 s and rinsed for 60 s. They were then randomly assigned to 4 groups: G1: air-water spray+drying (control); G2: ultrasonic cleaning in distilled water for 4 min+drying; G3: ultrasonic cleaning in 99.5% acetone for 4 min+drying; G4: ultrasonic cleaning in 70% alcohol for 4 min+drying. The ceramic blocks were silanized and cemented (RelyX ARC) to the composite blocks. Subsequently, the microtensile bond strength test (µTBS) was performed. In addition, EDS analysis was made to assess the elemental composition of the conditioned and cleaned ceramic surfaces. A significantly higher mean µTBS was obtained when specimens had been ultrasonically cleaned in distilled water (G2: 18.8 ± 0.4 MPa) (p < 0.05) compared to other groups (G1: 16.6 ± 0.5; G3: 16.1 ± 0.9; G4: 15.8 ± 1.4) (one-way ANOVA). EDS analysis indicated the presence of F- only in G1. Dissolved precipitates after HF etching were removed by ultrasonic cleaning. Cleaning the HF-etched ceramic surface ultrasonically in distilled water is recommended, instead of rinsing it with air-water spray only.

Dust Control with Use of Air-Water Spraying System / Redukcja Zapylenia Powietrza Z Wykorzystaniem Zraszania Powietrzno-Wodnego

Abstract Results from testing the dust control efficiency, when using air-water spraying system in comparison to the typical water spraying system are presented in the paper. The tests were carried out in conditions of longwall mining and at the places of run-of-mine transportation. Also the results of stand tests of different types of nozzles both for air-water and for water spaying systems carried out at KOMAG’s laboratory and in real conditions are presented. The benefits resulting from air-water spraying system have been determined.

Numerical Simulation and Experiment on Quenching Process of 718 Mould Steel with New Online Hardening Equipment

A new type online hardening equipment for quenching has been developed by University of Science and Technology Beijing and Dongbei Special Steel Group in Dalian Special Steel Co., LTD., which consists of strong water jet, medium water jet, weak water jet, air-water spray and side water jet and has flexible cooling and control ability. Based on the equipment, the online quenching process of 718 mould steel is performed by numerical simulation and field experiment. The result of temperature field by numerical simulation agrees well with that of experiment, which can prove that numerical simulation can be very good guidance for field experiment. Experimental tempering hardness difference of 718 mould steel can be controlled within 2 HRC in the whole plate according to numerical simulation. Prediction technology can meet the different cooling rate control and make quenching process comply with preset quenching route to guarantee material microstructure and performance.