High-speed Handpiece Research Articles

치과용 유니트 수관 물 빼기(Flushing)가 세균 오염도 감소에 미치는 영향

A wide variety of methods have been used to control Dental Unit Waterline (DUWL) contamination. Among the methods, flushing is mainly used because it is simple and easy to use. Generally, flushing of DUWL for 20 or 30 sec before using high speed handpieces or scalers is recommended. However, the appropriateness of flushing time was not investigated thoroughly. The purpose of this study was to check the effective time of flushing for decreasing bacterial contamination. Seven dental unit chairs were randomly selected in student clinical simulation laboratory for this experiment. DUWLs were continuously flushed and water samples were collected at an interval of 30 seconds for 15 minutes. From five dental unit chairs, water samples were collected every 10 seconds for 1 minute. Bacterial levels in water samples were examined by the culture method on R2A plates. After 10 second flushing of DUWLs, the number of bacteria significantly reduced and decreased continuously up to 40 seconds. However, even after the water was flushed for 15 minutes, the bacterial contamination level was not reduced below recommended bacteria level, 200 CFU/ml. In addition to flushing, the periodic chemical disinfection is required to control the DUWL water to the recommended level.

치과 의료장비의 소음 수준 평가

This research is aimed at cutting off hearing loss and other harmful factors due to noise and providing basic material for noise reduction plan. As the research method, this research assessed noise by measuring acoustic pressure level and frequency in various situation of non-treatment and treatment. As the measurement result, average noise degree of high speed handpiece of non-treatment, ultrasonic waves scaler, and low speed handpiece showed 58~66 dB(A). Average noise degree of scaling of treatment, tooth elimination, and denture adjust showed 73~81 dB(A). The result is inferior to recognized standards of noise induced hearing loss. But the result of assessing this with (noise rating) NR curve was NR-73~78, which exceeded general workplace noise standard. This level can cause hearing loss when exposed to a long time. Therefore, treatment office noise during dental treatment can cause psychological and physical damage in dental clinic employees, and it is urgently required to establish systematic and active noise reduction plan.

Influence of different Er,Cr:YSGG laser parameters on long-term dentin bond strength of self-etch adhesive

The aim of the present study was to evaluate the effects of erbium, chromium: yattrium-scandium-gallium-garnet (Er,Cr:YSGG) laser frequency on microtensile bond strength (μTBS) of a self-etch adhesive to dentin after 15-month water storage. The Er,Cr:YSGG laser can safely be used on dental hard tissue. However, no study has compared the effects of Er,Cr:YSGG laser parameters and aging by water storage on the bonding effectiveness of self-etch adhesives to dentin. Thirty-five bovine teeth were randomly assigned to the following seven groups (n = 5): group I (diamond bur with high-speed handpiece (control)), group II (Er,Cr:YSGG laser 3 W/50 Hz), group III (Er,Cr:YSGG laser 3 W/35 Hz), group IV (Er,Cr:YSGG laser 3 W/20 Hz), group V (Er,Cr:YSGG laser 6 W/50 Hz), group VI (Er,Cr:YSGG laser 6 W/35 Hz), and group VII (Er,Cr:YSGG laser 6 W/20 Hz). Clearfil SE Bond was applied to the prepared dentin, and the composites were placed and cured. Resin-dentin sticks with an approximate cross-sectional area of 0.8 mm(2) were obtained, and bond strength tests were performed at 24 h and 15 months of water storage after bonding. Data were analyzed with Kruskal-Wallis and Mann-Whitney U tests (p < 0.05). Laser irradiation resulted in significantly lower bond strengths when compared to bur treating. Fifteen-month water storage reduced bond strength for all groups. There was no significant difference among the effects of different laser frequencies on bond strength. It can be concluded that Er,Cr:YSGG laser used at the tested parameters may alter the dentin bond durability of self-etch adhesive.

Cutting efficiency of diamond burs operated with electric high-speed dental handpiece on zirconia.

Zirconia-based dental restorations are becoming used more commonly. However, limited attention has been given to the difficulties experienced, concerning cutting, in removing the restorations when needed. The aim of the present study was to compare the cutting efficiency of diamond burs, operated using an electric high-speed dental handpiece, on zirconia (Zir) with those on lithium disilicate glass-ceramic (LD) and leucite glass-ceramic (L). In addition, evaluation of the cutting efficiency of diamond burs on Zir of different thicknesses was performed. Specimens of Zir were prepared with thicknesses of 0.5, 1.0, 2.0, and 4.0mm, and specimens of LD and L were prepared with a thickness of 1.0mm. Cutting tests were performed using diamond burs with super coarse (SC) and coarse (C) grains. The handpiece was operated at 150,000rpm with a cutting force of 0.9N. The results demonstrated that cutting of Zir took about 1.5- and 7-fold longer than cutting of LD and L, respectively. The SC grains showed significantly higher cutting efficiency on Zir than the C grains. However, when the thickness of Zir increased, the cutting depth was significantly decreased. As it is suggested that cutting of zirconia is time consuming, this should be taken into consideration in advance when working with zirconia restorations.

In vitro evaluation of accuracy and precision of automated robotic tooth preparation system for porcelain laminate veneers

Statement of problemControlling tooth reduction for porcelain laminate veneers (PLVs) in fractions of millimeters is challenging. PurposeThe purpose of this study was to assess an automated robotic tooth preparation system for PLVs for accuracy and precision compared with conventional freehand tooth preparation. Material and methodsTwenty maxillary central incisor tooth models were divided into 2 groups. Ten were assigned to a veneer preparation with a robotic arm according to preoperative preparation design-specific guidelines (experimental group). Ten were assigned to conventional tooth preparation by a clinician (control group). Initially, all tooth models were scanned with a 3- dimensional (3D) laser scanner, and a tooth preparation for PLVs was designed on a 3D image. Each tooth model was attached to a typodont. For the experimental group, an electric high-speed handpiece with a 0.9-mm-diameter round diamond rotary cutting instrument was mounted on the robotic arm. The teeth were prepared automatically according to the designed image. For the control group, several diamond rotary cutting instruments were used to prepare the tooth models according to preoperative preparation design guidelines. All prepared tooth models were scanned. The preoperative preparation design image and scanned postoperative preparation images were superimposed. The dimensional difference between those 2 images was measured on the facial aspect, finish line, and incisal edge. Differences between the experimental and the control groups from the 3D design image were computed. Accuracy and precision were compared for all sites and separately for each tooth surface (facial, finish line, incisal). Statistical analyses were conducted with a permutation test for accuracy and with a modified robust Brown-Forsythe Levene-type test for precision (α=.05). ResultsFor accuracy for all sites, the mean absolute deviation was 0.112 mm in the control group and 0.133 mm in the experimental group. No significant difference was found between the 2 (P=.15). For precision of all sites, the standard deviation was 0.141 mm in the control group and 0.185 mm in the experimental group. The standard deviation in the control group was significantly lower (P=.030). In terms of accuracy for the finish line, the control group was significantly less accurate (P=.038). For precision, the standard deviation in the control group was significantly higher at the finish line (P=.034). ConclusionsFor the data from all sites, the experimental procedure was able to prepare the tooth model as accurately as the control, and the control procedure was able to prepare the tooth model with better precision. The experimental group showed better accuracy and precision at the finish line.

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

Composite bite blocks: Unraveling the mystery

Glass ionomer/composite bite blocks are used routinely for unraveling the interferences caused by occlusion/as splints. They are used during the initial phases of treatment and their removal requires the use of a diamond bur in a high-speed handpiece. Here, a technique is developed which involves easier removal of these blocks.

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.

Estudio comparativo in vitro de pulido de porcelana feldespática usando instrumentos intraorales y pastas diamantadas.

El presente estudio experimental in vitro compara mediante el uso de un rugosímetro (Surftest - III, Mitutoyo), la rugosidad superficial de porcelana feldespática abrasionada y después pulida, usando diferentes procedimientos con instrumentos intraorales como fresa diamantada grano fino, kits de pulido y pastas diamantadas de diferente granulación. Para el grupo control, las muestras fueron glaseadas y luego pulidas usando instrumentos extraorales en un laboratorio dental. Se realizaron pruebas estadísticas ANOVA y de comparación múltiple. Los resultados indican que una combinación adecuada de una fresa de diamante grano fino, las 3 gomas del kit Porcelain Polishing (Jota) y las pastas diamantadas Diamond Polish (Ultradent) de 1 pm y de 0,5 pm, usados en ese orden producen una menor rugosidad superficial en las muestras. Estos hallazgos son importantes ya que indican como alternativa, el pulido intraoral, después de abrasionar una restauración cerámica.

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.

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

Background The 'high-speed' (air turbine) handpiece is used extensively across many dental disciplines and the ability of clinicians to detect faulty handpieces is essential. Aim 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. Method 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. Results 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. Conclusion 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.

Influence of Image Filters and Variation in Horizontal Angle of Incidence of X-ray Beam in Digital Interproximal Radiographs for Diagnosis of Secondary Caries in Esthetic Restorations

Secondary or recurrent caries are located around restoration margins or under these lesions, and can lead to tooth loss. The interproximal or bite wing radiograph is the technique of choice to assist diagnosis of secondary caries. To evaluate diagnostic accuracy of secondary caries in pulpal walls artificially created in extracted human premolars, observed in digital bitewing radiographs using variations in horizontal X-ray beam angle of incidence and application of enhancement filters. The sample consisted of 20 healthy premolars, in which secondary caries lesions were simulated by means of subjecting the pulpal wall of the cavity to wear with spherical carbide drill half, fitted to a high speed handpiece, under constant cooling, focused perpendicular to the tooth surface. The orifices were filled with wax and all teeth were restored with composite resin Filtek Z350 XT(®). Later teeth were radiographed with a digital sensor complementary metal-oxide-semiconductor (CMOS) varying the horizontal angle at intervals of 2°, covering a range of -10 to +10°. The results showed that in the diagnosis of secondary caries, there was no statistically significant difference between the 2 pseudocolor filters, and negative and direct digital radiography. The pseudocolor filter no. 1 showed statistically significant differences, except at a horizontal angle of 0°, thus indicating lower efficiency in the diagnosis of secondary caries. Secondary caries with esthetic pulp wall restoration can be diagnosed irrespective of variation in the horizontal angle of incidence of the X-ray beam. The use of different radiographic enhancement filters did not result in improved diagnosis of secondary caries.

치과 진료실내의 세균오염도와 영향인자에 관한 연구

Objectives: The purpose of this study was to identify the stains causing infections in dental clinics by analyzing bacterial contamination, as well as to suggest improvements for infection control in dental clinics. Methods: In this study, a questionnaire survey of 47 dental hospitals and clinics located in Gyeonggi-do and Incheon, South Korea was administered from June 2013 to September 2013 and used to investigate the practice rates of infection control by dental hygienists and to analyze the bacterial contamination levels in dental offices. Results: In the studied institutions, the bacterial contamination levels of water lines were colony forming units (CFU)/mL for three-way syringes, for high-speed handpieces and for gargling water. The bacterial contamination levels of surfaces were in cuspidors, higher than in unit chairs () and light handles (). The mean bacterial cell count of water lines and surfaces was relatively high in all establishments founded 11 years ago or more, and the mean bacterial cell count of waterline handpieces was in establishments founded between one and five years ago, six to ten years ago and 11 years ago or more, which suggests that earlier foundation is associated with higher bacterial contamination levels with a statistical difference (p in at least 11-year-old establishments, statistically significantly higher among in one- to five-year-old () and six- to ten-year-old clinics () (p

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.

Fixed Partial Denture Treatment With Mini Dental Implants

Fixed Partial Denture Treatment With Mini Dental Implants

Magneto-aerostatic bearing for miniature air turbine

Under the circumstance of pursuing high speed and miniaturization, mini-type air turbines have been widely applied to high-speed dental handpieces in recent years. Among all the components of a mini-type air turbine, bearing is the most important part which significantly affects its efficiency. Friction, collision, and wear are the main causes to make the ball bearing unable to reach higher efficiency. Though very small sliding friction can be realized by the aerostatic bearing, its poor bearing capacity limits the application. This research combines the magnetic and aerostatic levitation principle to develop a magneto-aerostatic hybrid bearing for miniature air turbine. The aerostatic bearing undertakes the main function of the radial and the axial bearings. However, the air bearing also possesses a drawback, which is pneumatic hammer effect induced by the air compressibility. In order to eliminate the pneumatic instability, an axial passive magnetic bearing is integrated into the aerostatic bearing. With the magnetic bearing, not only the bearing capacity can be improved, but also the pneumatic hammer effect can be significantly damped. Both theoretical calculation and finite element method (FEM) are used to study the cause and elimination solution of the pneumatic instability. Through experimental testing, the performance of our developed magneto-aerostatic bearing is also verified. The magneto-aerostatic bearing suppresses the axial vibration over 57%, and also enhances its axial bearing capacity by 50%.

Crystallographic characterization of eggshells as scaffolds for bone regeneration

The aim of this work was to characterize six different eggshell types as future osseous regeneration scaffolds. The study design was cross-sectional observational. The study was conducted in the Laboratory of Materials and the chemical analysis in the Faculty of Chemistry, UNAM, Mexico. Fifty samples of fresh eggs were obtained, 10 from each species (hen, turkey, duck, dove and quail). Square-shaped pieces of about 2 x 2 cm were obtained from the eggshells by means of a high-speed handpiece with a # 701 carbide bur. From the total of eggshell pieces, the ones coming from fresh eggs were included, and the ones showing signs of fracture or spots were excluded. Their morphology was analyzed with a low vacuum scanning electron microscope (JEOL 5200), with an accelerating voltage of 20 kV. The chemical elemental analysis was performed with an EDAX energy dispersive spectrometer (EDS) and the chemical composition was determined by means of a Siemens diffractometer. All of the eggshells were constituted by calcium carbonates, and their outer structure was less porous than the inner one, sometimes with granules and cuticles firmly attached to the inner surface of the eggshell. The eggshell major chemical components were mainly: oxygen, calcium, phosphorous, magnesium, sulfur and carbon. There are no significant quantities of sulfur (S) in the turkey and quail eggshells. These kinds of eggshells have not been tested yet as a scaffold, but it is expected that they may be used soon in bone regeneration once the organic part is removed. Eggshells are largely waste material. The authors anknowledge the technical support to Chem. Rafael Ivan Puente Lee

Influence of the composition of different resin composites in the Knoop hardness and bond strength between tooth/restoration

Abstract The aim of this study was to evaluate the Knoop Hardness (KH) and bond strength (BS) among different resin composites. Three composites (Z100- 3 M/ESPE; Filtek Supreme-3 M/ESPE, Filtek Silorane-3 M/ESPE) were tested. Thirty bovine incisors (n = 10) were used. Conical cavities were prepared in the buccal surface of each tooth with a diamond bur (3131KG Sorensen, Barueri, SP, Brazil) with a high-speed water-cooled hand-piece in a standard cavity preparation appliance (2.0 x 2.0 x 1.5 mm), resulting in a C-Factor of 2.2. Two adhesive systems were used according to the manufacturer’s instructions (Single Bond 2 and Silorane System Adhesive - 3 M ESPE). The restorations were made respectively with Z100, Supreme and Silorane. The composites were inserted in a single increment and light cured with a LED unit, Freelight (3 M ESPE) for 40 s. After photo-activation the specimens were stored at 37°C in distilled water during 24 h. KH (HMV-2, Shimadzu) were performed in the top and bottom at each specimen. After that, the push-out test was performed with a universal testing machine (Model 4411, Instron). In the KH test the data were submitted to a two way ANOVA and Tukey’s test (α=5%). The mean of KHN and standard deviations were: Top - Z100 (74.1/9.0); Supreme (58.4/3.6); Silorane (42.8/6.2) and Bottom - Z100 (66.7/13.6); Supreme (61.2/3.6); Silorane (40.0/3.0). In the BS test the data were submitted to one way ANOVA and Tukey’s test (α=5%). The BS mean and standard deviations were: Z100 (12.6/5.2), Supreme (20.9/6.3), Silorane (29.7/9.0). Z100 had the highest KHN at the top and it was statistically different from the bottom. Supreme and Silorane had no differences between top and bottom. Silorane showed the highest BS mean differing statistically from the others. Differences in the composition of composite resins can to influence in the Knoop hardness and bond strength of restorations.

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.