How sandblasting on lingual surfaces can be carried out with minimum enamel damage: An in vitro study on human teeth.

OBJECTIVE: The aim was to assess the extent of enamel damage sandblasting might cause and to identify a combination of sandblasting durations and MicroEtcher nozzle-tooth surface distance (NTD) resulting in the least enamel damage. MATERIALS AND METHODS: Lingual surfaces of 30 human teeth were sandblasted with 2 different distances: 1, 2mm and 3 different durations: 1, 2, 3s and photographed using a light microscope. The cavity depth and diameter of the sandblasted teeth were measured on the light microscope's pictures. A pilot study was performed to minimize possible combinations of sandblasting durations and distances. To validate the measurement method, sandblasted teeth were ground cut for comparison. Inter-examiner reliability was assessed with Bland-Altman analysis. Mann-Whitney U-test was used to detect cavity and diameter changes for every sandblasting duration and NTD combination. RESULTS: From the pilot study sandblasting durations 1,2 and 3s and NTD<2mm were chosen. The cavity diameter of the sandblasted area did not change with increased sandblasting duration nor NTD (P>0.05). The cavity depth of the sandblasted area increased statistically with an increased sandblasting duration (P<0.05) but did not increase with an increase NTD (P>0.05). The 95% limits of inter-examiner agreement were narrow. CONCLUSION: All distance and duration combinations tested caused enamel damage. Sandblasting duration had greater impact on the cavity depth than the NTD. The blasting duration should, therefore, not exceed 2s and the NTD should be held at maximum 2mm to minimize the risk of unintentional spread.

New High-Translucent Cubic-Phase-Containing Zirconia: Clinical and Laboratory Considerations and the Effect of Air Abrasion on Strength.

Fabricating all-ceramic restorations with minimal or no application of a secondary phase while maintaining esthetics has been a sought-after goal of the dental profession. The objective has been development of a monolithic material with optical properties similar to the natural tooth without the need for layering porcelain. This article examines some of the newer cubic zirconia materials used in a monolithic form. The authors discuss laboratory-processing issues that affect esthetics, including evaluation of colorizing, sintering, finishing, and polishing, and assess initial translucency testing of several materials while evaluating the effect of air abrasion on flexural strength of these cubic zirconias. Lastly, the article demonstrates an anterior single-unit monolithic case with several of the newer materials.

The effect of air-abrasion and heat treatment on the fracture behavior of Y-TZP.

OBJECTIVES: This study evaluated how the flexural strength and fracture behavior of a zirconia-based ceramic (Y-TZP) were affected by pre- and post-sintering mechanical and thermal treatments. METHODS: Treatments included sandblasting with different particle size and type (30µm SiO2; 50 and 110µm Al2O3) and thermal conditioning. Two hundred bar-shaped specimens of pre-sintered Y-TZP ceramic (Lava Frame, 3M) were prepared (specimen dimensions: 25mm length×4mm width×0.7mm thickness) and divided into three groups (before sintering, after sintering and after sintering with heating treatment). The before sintering group specimens were airborne-particle abraded prior to dense sintering. Specimens from the after sintering group were airborne-particle abraded after sintering. The after sintering with heating treatment group specimens were submitted to a heating procedure after airborne-particle abrasion. The controls were the specimens that were sintered and not treated with any conditioning procedures. The specimens from all experimental conditions were analyzed by SEM, CLSM and XRD. All specimens were tested in four-point bending. Data were statistically analyzed using one-way ANOVA and Post Hoc tests (α=0.05). A Weibull analysis was used to analyze the strength reliability. RESULTS: Sandblasting pre-sintered zirconia before sintering significantly decreased the flexural strength, except when the smallest blasting particles were used (30µm SiO2). Phase transformation (t-m) was observed after sandblasting and reverse transformation (m-t) was observed after heating. SIGNIFICANCE: Sandblasting with 30µm SiO2 and 50µm Al2O3 allowed lower phase transformation. However, 30mm SiO2 presented better reliability.

The effect of sandblasting and different primers on shear bond strength between yttria-tetragonal zirconia polycrystal ceramic and a self-adhesive resin cement.

PURPOSE: To evaluate the effect of zirconia primers, air-abrasion, and tribochemical surface treatment methods on the shear bond strength between yttria-tetragonal zirconia polycrystal (Y-TZP) ceramic and self-adhesive resin cement. METHODS AND MATERIALS: Y-TZP ceramic surfaces were ground flat with 600-grit silicon carbide paper and then divided into seven groups of 10 and treated as follows: untreated (control), Monobond Plus, Z-PRIME Plus, ESPE Sil with CoJet, air-abrasion, Monobond Plus with air-abrasion, and Z-PRIME Plus with air-abrasion. Self-adhesive resin cement was placed onto the treated Y-TZP specimens for each group. All specimens were thermocycled and subjected to a shear bond strength test. Scanning electron microscope images of the fractured areas and x-ray diffraction (XRD) analysis of the surface-treated Y-TZP specimens were performed. Data were statistically analyzed using one-way analysis of variance and the Student-Newman-Keuls multiple comparison test (p<0.05). RESULTS: The Z-PRIME Plus treatment in combination with air-abrasion produced the highest bond strength (16.50±2.26 MPa), followed by air-abrasion (10.56±3.32 MPa), and then Monobond Plus combined with air-abrasion (8.93±3.13 MPa), ESPE Sil after CoJet application (8.54±3.98 MPa), and the Z-PRIME Plus group (8.27±2.79 MPa). The control (3.91±0.72 MPa) and Monobond Plus (4.86±1.77 MPa) groups indicated the lowest results (p<0.05). The XRD results showed the peaks of the monoclinic phase for the air-abrasion and CoJet treatment groups compared with the Y-TZP control. CONCLUSION: Z-PRIME Plus primer application after air-abrasion presented the best results for improving the bond strength between Y-TZP ceramic and self-adhesive resin cement.

Air abrasion before and/or after zirconia sintering: surface characterization, flexural strength, and resin cement bond strength.

The purpose of this in vitro study was to evaluate the effect of air-abrasion/zirconia sintering order on the yttria partially stabilized tetragonal zirconia polycrystal (Y-TZP) surface characterization (roughness, morphology, and phase transformation), flexural strength (FS), and shear bond strength (SBS) to a resin cement. Y-TZP specimens were air abraded with 50-µm Al2O3 particles after (AS), before (BS), or before and after zirconia sintering (BAS). For roughness (Ra), 30 block specimens (12×12×3.0 mm; n=10) had their surfaces analyzed by a profilometer. Next, on the air-abraded surfaces of these specimens, composite resin discs (n=30) were bonded with RelyX ARC. The bonded specimens were stored for 24 hours in distilled water at 37°C before shear testing. Failure mode was determined with a stereomicroscope (20×). The surface morphology (n=2) was evaluated by SEM (500×). For the four-point flexural strength test (EMIC DL2000), 39 bar-shaped specimens (20×4.0×1.2 mm; n=13) were air abraded according to the three conditions proposed, and an additional group (nonabraded) was evaluated (n=13). The quantitative analysis of phase transformation (n=1) was completed with Rietveld refinement with X-ray diffraction data. Ra (µm) and SBS (MPa) data were analyzed by one-way analysis of variance (ANOVA) and the Tukey test (α=0.05). Pearson correlation analysis was used to determine if there was a correlation between roughness and SBS. For FS (MPa) data, one-way ANOVA and the Dunnett C-test (α=0.05) were used. The air-abrasion/zirconia sintering order influenced significantly (p<0.001) Ra, SBS, and FS. The BS and AS groups presented the highest (1.3 µm) and the lowest (0.7 µm) Ra. The highest SBS (7.0 MPa) was exhibited by the BAS group, followed by the AS group (5.4 MPa) and finally by the BS group (2.6 MPa). All groups presented 100% adhesive failure. A weak correlation (r=-0.45, p<0.05) was found between roughness and SBS. The air-abrasion/zirconia sintering order provided differences in the surface morphology. The nonabraded (926.8 MPa) and BS (816.3 MPa) groups exhibited statistically similar FS values but lower values than the AS (1249.1 MPa) and BAS (1181.4 MPa) groups, with no significant difference between them. The nonabraded, AS, BS, and BAS groups exhibited, respectively, percentages of monoclinic phase of 0.0 wt%, 12.2 wt%, 0.0 wt%, and 8.6 wt%. The rougher surface provided by the air-abrasion before zirconia sintering may have impaired the bonding with the resin cement. The morphological patterns were consistent with the surface roughness. Considering the short-term SBS and FS, the BAS group exhibited the best performance. Air abrasion, regardless of its performance order, provides tetragonal to monoclinic transformation, while sintering tends to zero the monoclinic phase content.

[Subcutaneous emphysema following non-surgical peri-implantitis therapy using an air abrasive device: a case report]. / Subkutanes Emphysem nach nicht chirurgischer Periimplantitistherapie nach der Anwendung einer Air-Flow-Einheit.

Subcutaneous emphysema are rare complications in periodontology. In most cases, they resolve spontaneously. However, air might disperse into deeper facial spaces causing life-threatening complications such as compression of the tracheobronchial tree or the development of pneumomediastinum. Moreover, microorganisms might spread from the oral cavity into deeper spaces. Hence, rapid diagnosis of subcutaneous emphysema is important. Characteristic signs are both a shiftable swelling and a crepitation. In this case report, the case of a 69-year old man with a subcutaneous emphysema immediately after peri-implantitis therapy with the use of a glycine-based powder air-polishing device is described. Following therapy, air accumulated in the left side of the face. Seven days after non-surgical peri-implantitis therapy, the patient was asymptomatic with complete resolution of the emphysema.

Enamel roughness and incidence of caries after interproximal enamel reduction: a systematic review.

The aim of this study was to investigate the effect of interproximal enamel reduction (IER) on tooth surfaces regarding the level of enamel roughness after applying different IER methods and the caries risk of treated teeth. Seven electronic databases were systematically searched. Two independent reviewers rated the articles at every step according to predetermined eligibility criteria. Data on enamel roughness were pooled if the same IER method was used and arithmetic values were available. Data on occurrence of caries were suitable for the analysis if the same units for caries development were used. From 2396 citations initially identified, 18 articles met the inclusion criteria and were further considered (14 studying enamel roughness and four studying the risk of caries after IER). A meta-analysis of quantitative data regarding enamel roughness was not possible due to statistical heterogeneity; instead, the enamel roughness findings are only described. The meta-analysis of studies focusing on the incidence of caries revealed no statistical difference between treated and untreated enamel surfaces (p = NS) from 1 to 7 years after IER. Drawing reliable conclusions on enamel roughness after IER is difficult owing to the diversity of the available studies. Statistically, the occurrence of caries on surfaces previously treated with IER was the same as that on intact surfaces, indicating that IER does not increase the risk of caries on treated teeth.

The characterization of dentin defects produced by air polishing.

The objective of this study is to characterize the defects in the dentin surface after air polishing for three types of polishing powders and five different nozzle distances. Human teeth were embedded in acrylic resin and then polished until the dentin surface became exposed. The nozzle of the polisher was fixed at a specified distance (2, 3, 4, 5, or 6 mm) and orientation (45°) with respect to the dentin surface. The three powders were CLASSIC (NaHCO(3), 65 µm diameter), PERIO (glycine, 25 µm diameter), and SOFT (glycine, 65 µm diameter). With respect to nozzle distance, we find a significant difference in the mean defect depth only at 6 mm. The spray distance of 6 mm produced the shallowest defect depths. This variable had no effect on the defect volume. SOFT powder had significantly less depths and volumes of defects than the other two powders. The contact angle of the dentin increased significantly in all polishing tests, compared to an unpolished dentin surface (control). We find that spray distance of 6 mm from the nozzle of the polisher and orienting on 45° angle produced less dentin surface defects than any other distance in all powder systems used. At this distance, SOFT powder produced statistically significant smaller depth and volume defects than the other two powder groups.

The effect of air-polishing abrasives on wear of direct restoration materials and sealants.

BACKGROUND: Air-polishing devices (APDs) effectively remove supragingival staining. However, the use of APDs on restorative surfaces may result in clinically relevant surface damage and material loss. METHODS: The authors made plane specimens (N = 180) of dental restorative materials (Tetric EvoCeram [Ivoclar Vivadent, Schaan, Liechtenstein], Tetric Flow [Ivoclar Vivadent ], Grandio Flow [VOCO, Cuxhaven, Germany], Admira Seal [VOCO], Grandio Seal [VOCO]) and Ionofil Molar [VOCO]). The authors treated the specimens with standardized air abrasion, using three abrasives (Acclean Air Preventive Powder [Henry Schein, Langen, Germany], AirFlow Prophylaxis Powder [EMS, Nyon, Switzerland] and ClinPro Prophy Powder [3M ESPE, Seefeld, Germany]) for 10 seconds each. The authors used profilometric scanning to quantify defect depth and volume loss. RESULTS: The abrasive ClinPro Prophy Powder produced the smallest defect depth and volume loss. Tetric EvoCeram experienced the smallest defect depth, whereas the flowable composites showed the greatest defect depths and volume losses. Sealants showed defects comparable with those the authors found in the glass ionomer, which were significantly smaller than those found in flowable composites. CONCLUSIONS: Air polishing of sealants and restorative materials always results in substance loss and surface damage. The sealants performed better in terms of abrasion resistance than did the flowable composites tested. Among the air-polishing abrasives, ClinPro Prophy Powder caused the least abrasive damage. CLINICAL IMPLICATIONS: Clinicians should use low-abrasion powder for frequent cleaning of discolored restorations with APDs to avoid excessive abrasion of restorative materials.

O efeito do jateamento do esmalte na força de adesão na colagem de braquetes / The effect of air abrasion in enamel adhesion of orthodontic bracket

OBJETIVO: o propósito deste estudo in vitro foi avaliar o efeito do jateamento com óxido de alumínio na adesão de braquetes ortodônticos e compará-lo à tradicional técnica de condicionamento ácido do esmalte. METODOLOGIA: foram utilizados 80 dentes bovinos distribuídos aleatoriamente entre quatro grupos, sendo que a superfície do esmalte foi tratada da seguinte maneira: grupo 1 (somente jateamento com óxido de alumínio), grupo 2 (profilaxia com pedra-pomes e condicionamento com ácido), grupo 3 (jateamento com óxido de alumínio e condicionamento ácido) e grupo 4 (somente condicionamento ácido). Após, foi aplicado sistema adesivo e o braquete colado com resina. Os corpos-de-prova foram submetidos ao teste de cisalhamento e análise do IAR. Aos resultados foram aplicados o teste de variância múltipla (ANOVA) e a comparação entre pares (Tukey). Para a análise do IAR foi aplicado o teste Qui-quadrado. RESULTADOS: o grupo 1 apresentou a menor resistência ao cisalhamento (3,6MPa) e o 3 a maior (13,27MPa). A análise Qui-quadrado do IAR demonstrou que o tratamento da superfície do esmalte tem influência sobre a quantidade de remanescente de resina sobre o esmalte e os grupos 3 e 4 apresentaram a maior quantidade de resina aderida. CONCLUSÕES: o jateamento de óxido de alumínio não deve ser o único procedimento utilizado no preparo da superfície do esmalte na colagem de braquetes, porém, quando associado ao condicionamento ácido, mostrou-se eficaz no aumento da retenção entre esmalte e resina. Novos estudos são necessários visando menor dano do esmalte e adesão satisfatória.

AIM: The purpose of this study in vitro was to evaluate the effect of the air abrasion with Al-oxide in the adhesion of orthodontic brackets and compare with traditional technique of acid conditioning of the enamel. METHODS: Eighty bovine teeth distributed randomly between four groups had been used and the surface of the enamel was prepared in the following way: group 1 (only air abrasion), group 2 (enamel pumiced and acid conditioning), group 3 (air abrasion and acid conditioning) and group 4 (only acid conditioning). After, adhesive system was applied and bracket was bonded with resin. Shear bond was assessed and analysis of the IAR was performed. Test of multiple variance (ANOVA) and the comparison between pairs had been applied (Tukey) on the results. For the analysis of the IAR the Qui-square test was applied. RESULTS: Group 1 presented the lowest shear strength (3,6MPa) and 3 the greater (13,27MPa). The Qui-square analysis of the IAR demonstrated that the treatment of the enamel surface has influence on the amount of resin remainder on the enamel and groups 3 and 4 had presented the biggest amount of adhered resin. CONCLUSIONS: The air abrasion doesn't have to be the only procedure used in the preparation of the enamel surface in the brackets bonding, however, when associated to the acid conditioning it revealed efficient in adhesion increase. New studies are necessary aiming at lesser damage of the enamel and satisfactory adhesion.

Conservative aesthetic techniques for discoloured teeth: 2. Microabrasion and composite.

UNLABELLED: The first article in this series discussed the minimal intervention approach to discoloured teeth, starting with dental bleaching. This second article goes on to explain the technique of microabrasion and the use of direct composite techniques. CLINICAL RELEVANCE: Microabrasion and composite can provide minimally invasive treatments for discoloured teeth.

Microabrasion of cast metal margins--a warning.

Plastic test patterns were milled to simulate casting margins and were cast in a variety of dental alloys. The cast specimens were exposed to horizontal and vertical streams of low-pressure microabrasion with 50 microm aluminum oxide particles. Post-exposure measurements show all specimens were affected by microabrasion. Dentists and laboratory technicians who use microabrasion must be aware of the potential damage to casting margins.

Caries risk after interproximal enamel reduction.

INTRODUCTION: Air-rotor stripping (ARS) is a commonly used method to alleviate crowding in the permanent dentition. Its widespread acceptance, however, has been limited by the potential increase in caries risk of the abraded enamel surface. The aim of this study was to compare the susceptibility of ARS-treated enamel surfaces with intact surfaces in patients undergoing fixed orthodontic therapy. METHODS: Forty patients treated with ARS were examined clinically and radiographically for caries 1 to 6 years after interproximal enamel reduction. All patients were seen by their dentists for prophylaxis at 6-month intervals during active orthodontic treatment and were exposed to fluoridated water and toothpaste. Topical fluoride agents or sealants were not applied on the abraded surface after any ARS session. Caries incidence was compared between ARS-treated and unaltered surfaces within subjects. The decayed, missing, filled tooth (DMFT) and surface (DMFS) scores were used to evaluate the subjects' overall caries risk. RESULTS: Totals of 376 test and 376 control surfaces were examined. The number of interproximal lesions detected was found to be low with no statistically significant difference detected between the groups (test = 3; control = 6; P = .33]. The DMFT and DMFS scores increased significantly during the study period, indicating that these patients were clearly at risk of tooth decay (P <.001). CONCLUSIONS: The findings indicate that the risk of caries is not affected by ARS. Furthermore, our data show that the application of topical fluoride on the enamel surfaces immediately after ARS in patients exposed to fluoridated water and fluoride-containing toothpaste may not provide any additional benefit.

Bonding of resin composite luting cements to zirconium oxide by two air-particle abrasion methods.

OBJECTIVE: This study evaluated the shear bond strength of two resin composite luting cements to zirconium oxide ceramic substrate using two air-particle abrasion methods. METHODS: Two resin composite cements, RelyX Unicem (3M ESPE) and Panavia F (Kuraray), each with an acidic composition, were used in combination with a zirconium oxide (DCS Dental AG) substrate containing Al2O3 and SiO2 (Rocatec system, 3M ESPE) and two air-particle abrasion methods. The shear bond strength of the resin composite cement to the substrate was tested after the samples were either water-stored for one week or thermocycled following 24 hours of water storage. RESULTS: The RelyX Unicem resin composite cement specimens with the Rocatec treatment (20.9 +/- 4.6 Mpa and 20.1 +/- 4.2 MPa, respectively, n = 12) demonstrated the highest shear bond strength. Alternatively, the lowest values were obtained for the Panavia F resin cement samples, with Al2O3 air-particle abrasion in both storage conditions, water storage for one week (17.7 +/- 8.9MPa) or thermocycling after 24 hours of water storage (16.3 +/- 4.9 MPa). Neither storage condition or particle abrasion system significantly affected shear bond strengths (ANOVA, p > 0.05). CONCLUSION: It was concluded that two different surface conditioning methods and storage conditions did not significantly affect the bonding properties of Panavia F and RelyX Unicem resin composite luting cements to Zirconia.

Effects of surface conditioning on bond strength of metal brackets to all-ceramic surfaces.

The aim of this study was to determine the effectiveness of bonding brackets to ceramic restorations. Sixty feldspathic and 60 lithium disilicate ceramic specimens were randomly divided into six groups. Shear bond strength (SBS) and bond failure types were examined with six surface-conditioning methods: silane application to glazed surface, air particle abrasion (APA) with 25- and 50-microm aluminium trioxide (Al(2)O(3)), etching with 9.6 per cent hydrofluoric acid (HFA), and roughening with 40- and 63-microm diamond burs. Silane was applied to all roughened surfaces. Metal brackets were bonded with light cure composite, then stored in distilled water for 1 week and thermocycled (x500 at 5-55 degrees C for 30 seconds). The ceramic surfaces were examined with a stereomicroscope at a magnification of x10 to determine the amount of composite resin remaining using the adhesive remnant index. The lowest SBS values were obtained with HFA for feldspathic (5.39 MPa) and lithium disilicate (11.11 MPa) ceramics; these values were significantly different from those of the other groups. The highest SBS values were found with 63-microm diamond burs for feldspathic (26.38 MPa) and lithium disilicate (28.20 MPa) ceramics, and were not significantly different from 40-microm diamond burs for feldspathic and lithium disilicate ceramics (26.04 and 24.26 MPa, respectively). Roughening with 25- and 50-microm Al(2)O(3) particles showed modest SBS for lithium disilicate (22.60 and 26.15 MPa, respectively) and for feldspathic ceramics (17.90 and 14.66 MPa, respectively). Adhesive failures between the ceramic and composite resin were noted in all groups. Damage to the porcelain surfaces was not observed. The SBS values were above the optimal range, except for feldspathic ceramic treated with HFA and silane. With all surface-conditioning methods, lithium disilicate ceramic displayed higher SBS than feldspathic ceramic.

Effects of the Nd:YAG laser, air-abrasion, and acid-etchant on filling materials.

The purpose of this study was to determine any inadvertent effects of the neodymium: yttrium-aluminium-garnet (Nd:YAG) laser, air-abrasion, and ortho-phosphoric acid on some conventionally used dental filling materials [amalgam, composite resin, compomer, glass-ionomer cement (GIC), and ceromer], when they were used for purposes of margin etching and assessed according to standard enamel etching parameters using a total of five fillings. The surfaces of the filling materials were polished. One sample from each material group was exposed to laser (at 0.75 J, 15 pps) and air abrasion (with Al-oxide powder, 60 psi) for 2 s and to the 37% ortho-phosphoric acid for 60 s. The exposed materials were examined under Scanning Electron Microscopy (SEM). After laser treatment most specimens showed recrystallized areas, the GIC surface being the most affected. There were some pores and cavities on the amalgam surface following laser treatment. The abraded surfaces showed mechanical abrasions. The acid etchant showed the least effect. During the application of laser or air-abrasion, the adjacent tooth or filling surface must be protected or the dentist must be careful.

Análise morfológica da superfície de esmalte de dentes decíduos após a aplicação do sistema de abrasão a ar ou condicionamento ácido do esmalte. Estudo em microscopia eletrônica de varredura / Morphological analysis of enamel surface of deciduous teeth after air abrasion application or acid etching. Study using scanning electron microscopy

Foram comparadas, por meio de microscopia eletrônica de varredura, as superfícies de esmalte de dentes decíduos hígidos submetidos à abrasão a ar e ao condicionamento ácido. Os dentes foram fixados em bases de madeira com auxílio de godiva, e, após profilaxia com pedras-pomes e água, lavagem abundante e secagem, foram divididos nos seguintes grupos experimentais: GI - profilaxia com pedras-pomes e água com auxílio de escova Robinson e baixa rotação, seguidos de lavagem abundante (controle - 5 dentes), GII - aplicação do sistema de abrasão a ar utilizando 80psi de pressão, com ponta ativa em ângulo de 45° e 0,48mm de diâmetro, a 5mm de superfície dental, durante 15 segundos (10 dentes) e GIII - condicionamento do esmalte com ácido fosfórico a 37% durante 30 segundos (10 dentes). Pôde-se observar aumento na rugosidade superficial dos dentes do grupo GII, enquanto o GIII apresentou aumento significante das alterações superficiais com condicionamento definido dos centros dos prismas de esmalte (padrão tipo I). Os autores concluíram que, de acordo com as características superficiais, apenas a utilização da abrasão a ar promove pobres alterações superficiais rasas e irregulares na superfície dental, quando comparadas àquelas que receberam condicionamento ácido

Influence of air abrasion preparation on microleakage in glass ionomer cement restorations.

The aim of this study was to assess microleakage in class V cavities prepared by air abrasion or high-speed dental bur and restored with different glass ionomer cements. Sixty bovine incisors were equally divided into 6 groups: I, II and III (preparation by high-speed) and IV, V and VI (preparation by air abrasion). Groups I and IV were restored with Fuji IX; groups II and V with Ketac Molar; and groups III and VI with Vitremer. After 24 h (37 degrees C), specimens were thermocycled, isolated with nail varnish, immersed in a 0.2% Rhodamine B solution for 24 hours, sectioned longitudinally and analyzed for microleakage using an optical microscope connected to a digital camera and a computer. The images were digitized and a software allowed the quantitative evaluation of microleakage in millimeters. Data were analyzed by Wilcoxon and Kruskal-Wallis tests. It was observed that there were significant differences (p < 0.05) between incisal (enamel) and cervical (dentine/cementum) margins, mainly for Ketac Molar; there was no difference (p > 0.05) between preparation methods, except for group II (high-speed/Ketac Molar) that showed higher infiltration; regarding the materials, Ketac Molar demonstrated the highest microleakage values (p < 0.05), and only Vitremer sealed completely both margins of restorations. It was concluded that air abrasion preparation did not influence microleakage in class V restorations with the employed glass ionomer cements.

Root defects following air polishing.

AIM: Air-polishing devices (APDs) are highly effective in removing plaque and extrinsic staining. Their application on root surfaces, however, may result in clinically relevant substance removal, limiting the use in patients with periodontitis, where denuded root surfaces are frequently found. Therefore, the purpose of the study was to assess the influence of different working parameters on root damage and to identify those minimizing root damage. MATERIAL AND METHODS: Defect depth and defect volume after instrumentation of roots with an APD (Dentsply Prophy-Jet) using conventional NaHCO3 powder at instrumentation times of 5, 10 and 20 s, combinations of low, medium and high powder and water settings, distances of 2, 4 and 6 mm, and angulations of 45 degrees and 90 degrees were quantified laseroptically. A total of 297 roots were instrumented and parameter combinations were performed in triplicate. The influence of each working parameter on substance loss was determined by multiple regression analysis. RESULTS: Time had the greatest influence on defect volume and depth (beta-weights 0.6 and 0.57, respectively), when compared with powder setting (beta-weights 0.49 and 0.3) and water setting (beta-weights 0.28 and 0.3). Variations in distance affected defect depth (beta-weight 0.44), but not volume (beta-weight 0.04). No major differences were found at 45 degrees and 90 degrees. Various parameter combinations led to maximal defect depths of 473.5 +/- 26.2 micro m within 20 s. CONCLUSION: Root damage varies among combinations of working parameters. Using the APD with the assessed NaHCO3 powder, all parameter combinations led to substantial root damage. Thus, APDs using NaHCO3 may not be safely utilized on exposed root surfaces.

[Preparation of hard dental tissues by aeroabrasive method]. / Preparirovanie tverdykh tkanei zubov s pomoshch'iu vozdushno-abrazivnogo metoda.

The efficiency of aeroabrasive preparation (AAP) of teeth was evaluated by clinical methods and scanning electron microscopy. The authors conclude that the use of AAP should be confined to the treatment of surface and medium caries. Analgesia before AAP is obligatory, except cases with preparation of fissures for preventive hermetization. The use of AAP is absolutely contraindicated in cases of allergic reactions in the patient, dentist, or assistant. Methods for protection of the dentist, assistant, and patient during the use of AAP are discussed.