Air Turbine Handpiece Research Articles

Assessing the cutting efficiency of different burs on zirconia substrate.

Cutting dental zirconia for endodontic access preparation is difficult. Therefore, this study aimed to determine cutting efficiency of various burs when cutting this material. An air turbine handpiece was used in a customised test rig to cut sintered zirconia specimens, using a conventional blue band diamond, two different zirconia-cutting diamond and a zirconia-cutting tungsten carbide bur. Position and speed of the bur were continuously determined using wireless data acquisition over two successive five-minute runs. Differences in cutting efficiency were statistically analysed. Burs were examined using light and scanning electron microscopy (SEM). All diamond burs cut zirconia more efficiently than the tungsten carbide bur. Overall, all burs showed decreasing cutting efficiency over time. SEM images showed discernible wear and damage to the cutting portion of each bur head. It is concluded that zirconia-cutting burs are advantageous regarding durability, and carbide burs are rather ineffective against carbide substrate.

Psychoacoustic evaluation of noise emitted by dental air-turbine handpieces

Psychoacoustic evaluation of noise emitted by dental air-turbine handpieces

The effect of surface treatments on dental zirconia: An analysis of biaxial flexural strength, surface roughness and phase transformation

This study investigates the effect of selected surface finishing techniques on the biaxial flexural strength, surface roughness and phase transformation of a zirconia dental restorative material. Fully-sintered zirconia discs (⌀19.5 mm × 0.85 mm) were treated on one side with a single or a combination of the following treatments: diamond and/or tungsten-carbide burs without water coolant in an air-turbine handpiece, air-particle abrasion, rubber-point polishing in a contra-angle handpiece, or no treatment (control). Biaxial flexural strength (BFS) (eleven groups, n = 10) was determined using a universal testing machine and surface roughness (thirteen groups, n = 6) was assessed using a profilometer. Results were analysed using one-way ANOVA and Student-Newman-Keuls Post-hoc test (α = 0.05) with Bonferroni correction. Specimens were observed under scanning electron microscopy (SEM) and x-ray diffraction (XRD) for their microstructure and crystalline phases respectively. Grinding with diamond burs did not weaken zirconia (p > 0.0045) but produced rougher surfaces than the control group (p < 0.0038). Tungsten-carbide burs smoothened diamond ground specimens (p < 0.0038) for both grits of diamond. Specimens ground by tungsten-carbide burs have significantly reduced mean BFS (p < 0.0045) by up to two-thirds and SEM revealed fine surface cracks. Air-particle abrasion restored the mean BFS of tungsten-carbide ground specimens to control levels (p > 0.0045) and surface cracks were not observed. Phase transformation was not detected by XRD. Dental zirconia ground dry with tungsten-carbide burs has a significantly reduced BFS and a smooth but defective surface. These defects may be removed and BFS restored by air-particle abrasion. The use of tungsten-carbide burs for grinding dental zirconia should be cautioned. Diamond grinding does not weaken zirconia but requires further polishing.

歯科用エアー・タービン・ハンドピースの開発に関する基礎的研究 第1報 歯科用エアー・タービン・ハンドピースの騒音の解析

歯科用エアー・タービン・ハンドピースの開発に関する基礎的研究 第1報 歯科用エアー・タービン・ハンドピースの騒音の解析

The effects of dry and wet grinding on the strength of dental zirconia

Abstract The purpose of this study was to evaluate the effect of different dry and wet surface finishing on the mechanical strength and surface characters of a dental yttria-stablized zirconia ceramic (Y-TZP). Surface grinding treatments with a dental air turbine handpiece were performed with: coarse diamond (DC) and fine diamond (DF), tungsten carbide (Tc) and fine tungsten carbide (TcF) burs with or without water coolant. Air particle abrasion with 50 µm alumina (APA), combination of burs treatments or burs-abrasion, i.e. DC-TcF and DC-APA, were also performed with non-treatment group as control (C). Statistical analyses (α = 0.05) on results revealed that all surface treatments significantly increased the surface roughness (Ra) than control (p i.e. grain sizes in these specimens were smaller than the control (60 nm for C). This study outcome suggested that tungsten carbide burs should be avoided for grinding Y-TZP because of significant reduction in the BFS. Water cooling during grinding did not consistently reduce the potential heat damaging effects expected with dry grinding.

The effect of Er:YAG laser and bulk filled composite type on marginal adaptation of class II cavities: an SEM analysis study

Purpose: To evaluate the effect of cavity preparation method (Er:YAG laser or diamond bur) and bulk-filled composite material type on marginal adaptation mesial occlusal (MO) class II cavities. Materials and Methods: Two-surface box cavities (4-mm proximal depth and 5-mm occlusal width) were prepared on 60 human mandibular molar teeth. Cavities were prepared using Er:YAG laser or diamond burs in an air-turbine hand-piece. All cavities were applied Single Bond Universal dentin bonding agent. The cavities were further subdivided into three subgroups according to the restorative material used; two bulk-filled composites [Filtek Bulk Fill Posterior (3M ESPE) and SonicFill 2 (Kerr)] and one traditional composite material Filtek Ultimate Universal Restorative (3M ESPE). Restorations were evaluated using scanning electron microscopy at ×200 magnification for their adaptation to the approximal margins of the tooth. Results were analyzed using the two-way ANOVA and Tukey Post Hoc Test (p < 0.05). Results: A total of 900 SEM figures were obtained from all groups. Filtek Bulk Fill Posterior, SonicFill 2, and Filtek Ultimate Universal Restorative exhibited statistically similar gapped margins. However, the lowest scores of gapped margins were observed with SonicFill 2 (4.22%). Conclusions: Completely gap-free margins were not obtained with any of the tested materials. Bulk-fill composite materials showed similar marginal adapatation compared with standard composite. Marginal adaptation of Er:YAG laser prepared cavities was more irregular and had more gaps, but was statistically similar to diamond bur-prepared cavities.

The effect of abrading and cutting instruments on machinability of dental ceramics.

The aim was to investigate the effect of machining instruments on machinability of dental ceramics. Four dental ceramics, including two zirconia ceramics were machined by three types (SiC, diamond vitrified, and diamond sintered) of wheels with a hand-piece engine and two types (diamond and carbide) of burs with a high-speed air turbine. The machining conditions used were abrading speeds of 10,000 and 15,000 r.p.m. with abrading force of 100 gf for the hand-piece engine, and a pressure of 200 kPa and a cutting force of 80 gf for the air-turbine hand-piece. The machinability efficiency was evaluated by volume losses after machining the ceramics. A high-abrading speed had high-abrading efficiency (high-volume loss) compared to low-abrading speed in all abrading instruments used. The diamond vitrified wheels demonstrated higher volume loss for two zirconia ceramics than those of SiC and diamond sintered wheels. When the high-speed air-turbine instruments were used, the diamond points showed higher volume losses compared to the carbide burs for one ceramic and two zirconia ceramics with high-mechanical properties. The results of this study indicated that the machinability of dental ceramics depends on the mechanical and physical properties of dental ceramics and machining instruments. The abrading wheels show autogenous action of abrasive grains, in which ground abrasive grains drop out from the binder during abrasion, then the binder follow to wear out, subsequently new abrasive grains come out onto the instrument surface (autogenous action) and increase the grinding amount (volume loss) of grinding materials.

Spread of infection to skull base via infratemporal fossa after dental extraction related to the use of a high‐speed hand piece: a case report

AbstractInfection is a recognized complication of surgical extractions. However, with incorrect technique and use of inappropriate dental equipment, the chance of post‐operative complications increases. This is a case report that describes the extensive spread of infection to the skull base after a surgical extraction of a lower right wisdom tooth. The improper use of the high‐speed air turbine hand piece was likely to have contributed to the progression and extent of the life‐threatening infection.

Performance and Internal Flow of a Dental Air Turbine Handpiece

An air turbine handpiece is a dental abrasive device that rotates at high speed and uses compressed air as the driving force. It is characterized by its small size, light weight, and painless abrading due to its high-speed rotation, but its torque is small and noise level is high. Thus, to improve the performance of the air turbine handpiece, we conducted a performance test of an actual handpiece and a numerical analysis that modeled the whole handpiece; we also analyzed the internal flow of the handpiece. Results show that experimental and calculated values were consistent for a constant speed load method with the descending speed of 1 mm/min for torque and turbine output. When the tip of the blade was at the center of the nozzle, the torque was at its highest. This is likely because the jet from the nozzle entered the tip of the blade from a close distance that would not reduce the speed and exited along the blade.

A Numerical Study on Performance of Dental Air Turbine Handpieces

In the present work, the original dental air turbine handpieces were disassembled and their parts were modeled using reverse engineering. Then, simulation of dental cartridge was performed and the effect of different parameters was investigated. In dental air turbines, the flow channel and blade shape have major influence on the torque, rotating speed, and power performance. This research is focused on the turbine impeller and flow channel diameter. For this aim, three types of dental cartridges with different blades, nozzle diameter and the gap size between air turbine and casing were analyzed. The effect of air inlet pressure on torque, total force, air density and temperature distribution were investigated using computational fluid dynamic (CFD) simulation and related graphs were extracted. The results showed the turbine impeller designs including impeller diameter and blade shape can have major impacts on the torque and performance.DOI: http://dx.doi.org/10.5755/j01.mech.23.5.15477

Designing high-speed dental air-turbine handpiece by using a computational approach

The high-speed dental air-turbine handpieces are widely used in the dentistry as a tool for cutting and drilling a tooth. The impeller of the air-turbine handpiece rotates a cutting bur through the compressed-air. Two dental handpieces which have standard type head (Model 1) and torque type head (Model 2) were designed using computational analysis. The advanced existing high-speed dental air-turbine handpieces were investigated to compare with the designed dental handpieces. The computational domain of the air-turbine was investigated using ANSYS CFX software. The impeller blade type which has high torque value was selected to design the air-turbine impeller. The performance of the designed handpieces was verified through the measurements and the pre-clinical tests. The results showed that the newly designed handpieces had excellent performance which is compatible with existing advanced handpieces.

Study on Internal Flow and Performance of a Dental Air Turbine Handpiece

Study on Internal Flow and Performance of a Dental Air Turbine Handpiece

Effect of various grit burs on marginal integrity of resin composite restorations.

The purpose of this study was to evaluate the generation of enamel cracks and gaps at the cavosurface margin of resin composite restorations using various burs. Saucer-shaped cavities with a bevel were prepared on mid-coronal buccal or lingual surfaces of extracted human molars using a regular-grit round diamond bur, a fine-grit diamond bur, a superfine-grit diamond bur or a six-bladed tungsten carbide bur with an air turbine handpiece. The enamel margin of the cavity in each group was observed by a light microscope. Cavities were restored with a self-etching adhesive and a light-cured composite resin. After thermocycling, enamel cracks and gaps at the cavosurface margins were observed and scored. Specimens were sectioned longitudinally in two halves, and the resin-cavity interface was observed by means of a light microscope. In cavity preparation, the regular-grid diamond bur and the tungsten carbide bur caused more cracks in the marginal enamel than other groups. From the surface and sectioned surface observation of restored teeth, the superfine-grit diamond bur generated fewer cracks and gaps than the other burs.

Statistical Analysis for Subjective and Objective Evaluations of Dental Drill Sounds.

The sound produced by a dental air turbine handpiece (dental drill) can markedly influence the sound environment in a dental clinic. Indeed, many patients report that the sound of a dental drill elicits an unpleasant feeling. Although several manufacturers have attempted to reduce the sound pressure levels produced by dental drills during idling based on ISO 14457, the sound emitted by such drills under active drilling conditions may negatively influence the dental clinic sound environment. The physical metrics related to the unpleasant impressions associated with dental drill sounds have not been determined. In the present study, psychological measurements of dental drill sounds were conducted with the aim of facilitating improvement of the sound environment at dental clinics. Specifically, we examined the impressions elicited by the sounds of 12 types of dental drills in idling and drilling conditions using a semantic differential. The analysis revealed that the impressions of dental drill sounds varied considerably between idling and drilling conditions and among the examined drills. This finding suggests that measuring the sound of a dental drill in idling conditions alone may be insufficient for evaluating the effects of the sound. We related the results of the psychological evaluations to those of measurements of the physical metrics of equivalent continuous A-weighted sound pressure levels (LAeq) and sharpness. Factor analysis indicated that impressions of the dental drill sounds consisted of two factors: “metallic and unpleasant” and “powerful”. LAeq had a strong relationship with “powerful impression”, calculated sharpness was positively related to “metallic impression”, and “unpleasant impression” was predicted by the combination of both LAeq and calculated sharpness. The present analyses indicate that, in addition to a reduction in sound pressure level, refining the frequency components of dental drill sounds is important for creating a comfortable sound environment in dental clinics.

Multivariate evaluation of the cutting performance of rotary instruments with electric and air-turbine handpieces

Laboratory studies of tooth preparation often involve single values for all variables other than the one being tested. In contrast, in clinical settings, not all variables can be adequately controlled. For example, a new dental rotary cutting instrument may be tested in the laboratory by making a specific cut with a fixed force, but, in clinical practice, the instrument must make different cuts with individual dentists applying different forces. Therefore, the broad applicability of laboratory results to diverse clinical conditions is uncertain and the comparison of effects across studies difficult. The purpose of this invitro study was to examine the effects of 9 process variables on the dental cutting of rotary cutting instruments used with an electric handpiece and compare them with those of a previous study that used an air-turbine handpiece. The effects of 9 key process variables on the efficiency of a simulated dental cutting operation were measured. A fractional factorial experiment was conducted by using an electric handpiece in a computer-controlled, dedicated testing apparatus to simulate dental cutting procedures with Macor blocks as the cutting substrate. Analysis of variance (ANOVA) was used to assess the statistical significance (α=.05). Four variables (targeted applied load, cut length, diamond grit size, and cut type) consistently produced large, statistically significant effects, whereas 5 variables (rotation per minute, number of cooling ports, rotary cutting instrument diameter, disposability, and water flow rate) produced relatively small, statistically insignificant effects. These results are generally similar to those previously found for an air-turbine handpiece. Regardless of whether an electric or air-turbine handpiece was used, the control exerted by the dentist, simulated in this study by targeting a specific level of applied force, was the single most important factor affecting cutting efficiency. Cutting efficiency was also significantly affected by factors simulating patient/clinical circumstances and hardware choices. These results highlight the greater importance of local clinical conditions (procedure, dentist) in understanding dental cutting as opposed to other hardware-related factors.

The ultrastructure of subgingival dental plaque, revealed by high-resolution field emission scanning electron microscopy

Objectives/Aims:To explore the ultrastructure of subgingival dental plaque using high-resolution field emission scanning electron microscopy (FE-SEM) and to investigate whether extracellular DNA (eDNA) could be visualised in ex vivo samples.Materials and Methods:Ten patients were recruited who fulfilled the inclusion criteria (teeth requiring extraction with radiographic horizontal bone loss of over 50% and grade II/III mobility). In total, 12 teeth were extracted using a minimally traumatic technique. Roots were sectioned using a dental air turbine handpiece, under water cooling to produce 21 samples. Standard fixation and dehydration protocols were followed. For some samples, gold-labelled anti-DNA antibodies were applied before visualising biofilms by FE-SEM.Results:High-resolution FE-SEMs of subgingival biofilm were obtained in 90% of the samples. The sectioning technique left dental plaque biofilms undisturbed. Copious amounts of extracellular material were observed in the plaque, which may have been eDNA as they had a similar appearance to labelled eDNA from in vitro studies. There was also evidence of membrane vesicles and open-ended tubular structures. Efforts to label eDNA with immune-gold antibodies were unsuccessful and eDNA was not clearly labelled.Conclusions:High-resolution FE-SEM images were obtained of undisturbed subgingival ex vivo dental plaque biofilms. Important structural features were observed including extracellular polymeric material, vesicles and unusual open tubule structures that may be remnants of lysed cells. The application of an eDNA immune-gold-labelling technique, previously used successfully in in vitro samples, did not clearly identify eDNA in ex vivo samples. Further studies are needed to characterise the molecular composition of the observed extracellular matrix material.

Can you identify faults in a high-speed handpiece?

Holliday R, Venugopal S, Howell A, Keys W (2015) Operator's ability at assessing a high-speed (air turbine) handpiece before use: an audit. Br Dent J 218: doi: 10.1038/sj.bdj.2015.40

A testing methodology for suck-back behavior of high-speed air-turbine dental handpiece

치과용 고속 에어터빈 핸드피스는 압축공기를 이용하여 핸드피스 헤드 내부의 임펠러를 구동시키는 치아절삭에 사용되는 치과용 의료기기이다. 압축공기의 유동특성에 따른 압력 변화로 인하여 고속 치과용 에어터빈 핸드피스는 사용 중 기체 흡입 현상이 발생하는데 이런 현상을 에어터빈 핸드피스의 suck-back 현상이라고 한다. Suck-back 현상 때문에 치료 시 환자 구강 내의 혈액, 박테리아 등 유해물질이 핸드피스의 내부로 흡입되는데 치과용 에어티빈 핸드피스는 일회용 의료기기가 아니므로 여러 환자들한테 사용될 때 설령 소독하더라도 교차감염(cross-infection)의 위험이 발생하게 된다. 하지만 suck-back 현상에 대해 평가하는 연구가 아직 많이 부족한 상태이다. 연구에서는 suck-back을 방지할 수 있는 기능으로 설계된 상용화 된 5개 제품의 핸드피스에 대해 특별히 제작된 측정 장치를 이용하여 suck-back 성능을 평가하였다. 실험은 측정하려는 5사 제품의 구동 시 최대 압력, 정지 순간의 최소 압력을 측정하고 suck-back 현상이 지속되는 시간을 측정하였다. 실험 결과 A사 제품은 최소 압력이 0 bar로써 suck-back 현상이 발생하지 않았다. 반면 기타 4사의 제품은 suck-back 현상이 발생하였는데 그 중 B사 제품은 평균값 -0.00bar(-0.01bar부터 0bar 사이의 값), E사 제품은 -0.01(0)bar, C사 제품은 -0.019(0.003)bar, D사 제품은 -0.04(0)bar의 결과를 보였다. 또한 suck-back 현상의 지속 시간은 B사 제품이 1.83초로 가장 오래 유지되었으며 그 다음으로 D사 제품이 1.82초, E사 제품은 1.56초, C사 제품은 1.30초, 그리고 A사 제품은 0초로 가장 짧았다. 실험 결과 본 연구에서 고안한 에어터빈 핸드피스의 suck-back 현상 시험 방법은 정량적으로 측정할 수 있을 것으로 사료되었다.

Effects of handpiece speed on the performance of undergraduate dental students in preclinical training

Abstract Objective Low-speed high-torque handpieces are popular for the pre-clinical training of dental students. However, in clinical practice, high-speed air turbine handpieces are commonly used. This dissimilarity creates a gap between pre-clinical and clinical training skills. The current study sought to evaluate the effects of the use of high-speed and low-speed handpieces by dental students during their pre-clinical training. Methods Twenty-one undergraduate dental students at the College of Dentistry of Taibah University participated in this study. Each student was asked to prepare class I cavities using high-speed air turbine and low-speed/high-torque handpieces. The time required for cavity preparation was recorded by the authors. The prepared cavities were evaluated for quality and skill using a six-point scale. The data were statistically analysed with paired t and Mann–Whitney tests. Results There was no significant difference in cavity preparation time between the low-speed and high-speed handpieces (538.29 and 483.76 s, respectively). The evaluations of the cavities revealed no difference in the quality of preparations between the low- and high-speed handpieces. Additionally, no significant difference in the surface roughness of the preparations was observed. Conclusions The type of handpiece did not influence the learning capabilities of the undergraduate dental students in the preparation of preparing class I cavities. This study did not observe any significant differences between the cavities that were prepared by our students using either high-speed or low-speed handpieces.

Operator's ability at assessing a high-speed (air turbine) handpiece before use: an audit.

The 'high-speed' (air turbine) handpiece is used extensively across many dental disciplines and the ability of clinicians to detect faulty handpieces is essential. The primary aim of this audit was to determine the proportion of participants who could correctly identify unsafe handpieces. Secondary aims were to determine the proportion that had previous training on the topic and determine whether an educational video could improve scores. Eighty participants completed the first round of audit. They were asked to inspect seven handpieces, five of which were faulty, with three being classed as unsafe. After the intervention (educational sessions and distribution of a video) a second round of audit was completed on 69 participants. The ability to detect the three unsafe handpieces increased from 10% to 44% over the two rounds of audit. In the second round the highest score obtained was by those who had received the intervention, 77%. The lowest score, 14%, was by those who had not received the intervention. Nine percent of participants in the first round stated they had previously had training on handpiece inspection and none of these participants identified the three unsafe handpieces. This audit has highlighted that there is a knowledge deficiency with regards to air turbine handpiece safety and inspection. We have shown that introduction of a simple education video can have an impact on dentists and students abilities to detect unsafe faults. We have already introduced this into the undergraduate curriculum in our school and we aim to also raise awareness within the dental community.