Pumice Slurry Research Articles

Comparative evaluation of microleakage and penetration depth of ACP containing pit and fissure sealant and flowable composite - An in-vitro study.

The present in vitro study evaluated and compared the microleakage and penetration depth of ACP containing pit and fissure sealant with flowable composite. Sixty extracted non-carious premolars were categorized into four groups of 15 samples each. Sealant was applied after the Occlusal surfaces of the sample teeth were prophylactically treated with pumice slurry. Later, the teeth were thermocycled and immersed in methylene blue for a period of 24 hours. The samples were buccolingually sectioned and analysed under a stereomicroscope. Statistical analysis was carried out to compare the microleakage and depth of penetration. Flowable nanocomposite gave comparable results with that of the sealant in terms of microleakage. Nano-hybrid flowable composite performed better with respect to depth of penetration between tested materials with the difference being statistically significant. Flowable nanocomposite can be considered as a promising substitute for sealing fissures and thus can be endorsed to caries susceptible pediatric patients. Key words:Depth of Penetration, Sealants, Microleakage.

Knowledge, Attitude, and Practices toward the Novel Coronavirus Infection in Dental Laboratories in the Kingdom of Saudi Arabia: Cross-Sectional Study.

This study aimed to assess dental technologists/technicians knowledge, attitudes, and practice during the COVID-19 pandemic in Saudi Arabia. This cross-sectional study was conducted among workers in dental laboratories in Saudi Arabia. A validated questionnaire was developed based on previous literature and distributed online. The questionnaire assessed the study population's knowledge, attitude, and practice regarding infection control protocol for COVID-19. Descriptive statistics of categorical variables were conducted. The response rate was 58.3%, where most respondents are male at a rate of 97%. Most of the participants (82%) were aware of the various infection control measures for COVID-19 in a dental laboratory. Forty-eight participants showed a level of knowledge range between 80 and 100%, while 27 and 30 participants reported moderate and low level of knowledge, respectively. Only 67% of the participants strongly agree that dental cast and fabricated/repaired restorations should be transferred in a very close and protective package to control infection. About 70% of participants indicated they always wear protective gear/goggles and should be warned while working in the dental laboratory. As the pumice slurry was utilized frequently to clean and polish the prostheses, 66% of participants agreed that pumice slurry should be always changed regularly. Regarding COVID-19 infection control procedures, dental technologists/technicians showed good knowledge, attitude, and practice; however, considering how infectious the virus is, more measures should be taken into consideration. Effective communication and collaboration between the laboratory and the dental clinic are essential for infection control.

A Comparative Evaluation of Different Methods PF Cleaning and Preparing Occlusal Fissures, Before Placement of Pit and Fissure Sealant: A Stereomicroscopic Study

Aim and objective The study was aimed to comparatively evaluate the effect of different methods of cleaning and preparation of occlusal surfaces on microleakage of pit and fissure sealant. Materials and method: Eighty (80) sound extracted premolars served as samples and were divided into four categories according to the method of cleaning and preparation of occlusal surfaces. Prior to sealant placement. The groups were: A Dry Brush, B Pumice Slurry Air Polishing and D Prophylaxis Paste. In each group, subsequent to cleaning of occlusal surfaces with the method assigned to, pit and fissure sealant was applied. The samples were then kept in an incubator, thermocycled and then immersed in methylene blue dye. Each tooth was sectioned longitudinally into two halves and observed under stereomicroscope for microleakage using a criteria given by Cooley et al. Statistical analysis: Discrete microleakage score of groups is summarized in number (n) and percentage (%).Result: Comparing the microleakage score of four groups, χ2 test showed significantly different microleakage score among the groups (χ2 =33.96, P <0.001). Conclusion: Microleakage score showed both pumice slurry (Group B) and especially air polishing (Group C) to be significantly more superior than prophylaxis paste (Group D) and dry brush (Group A).

Evaluation of enamel colour changes with orthodontic bonding an in vitro study

Aesthetics is an integral part of orthodontics, and color is an important aspect of aesthetics. Hue, value, and chroma are the three objective variables used to describe color. The tooth color exhibits a large variation influenced by the structure of enamel and dentin. Enamel colour alterations may derive from the irreversible penetration of resin tags into the enamel structure at depths reaching 50 µm. Natural Teeth: A total of 80 extracted premolar teeth were collected and then washed thoroughly with plain water and stored in normal saline to prevent them from drying up.Eighty human premolar teeth that had been previously extracted from orthodontic patients.All the teeth selected were cleansed by using a rubber cup and pumice slurry for 20 seconds on a slow speed contra angle hand piece (10,000 rpm), rinsed thoroughly with saline for 10 seconds and air-dried with gentle jets of oil-free compressed air.In this study shows the frequency distributions of color difference ΔE at various time points in Transbond XT group. The mean difference before treatment and debonding and finishing (ΔE1) was 0.91± 0.43, mean difference before treatment and photogeing (ΔE2) was 1.49±0.85 and mean difference after debonding and finishing and photoageing (ΔE3) was 0.81±0.51. The frequency distributions of ΔE at various time points in Ormco group. The mean difference before treatment and debonding and finishing (ΔE1) was 0.72±0.24, mean difference before treatment and photogeing (ΔE2) was 1.88±0.83 and mean difference after debonding and finishing and photoageing (ΔE3) was 0.97±0.55. Ormco Enlight showed highest enamel color change of ΔE2 value 2.92 after debonding & finishing. Rely A bond showed least enamel color change of ΔE2 value 2.80. Of all the groups studied there is a significant color change in the enamel but less than the minimum threshold value of ΔE 3.7 units.

Surface roughness and marginal adaptation of stereolithography versus digital light processing three-dimensional printed resins: An in-vitro study.

The aim of this study was to assess surface roughness and marginal adaptation of Stereolithographic versus Digital Light Processed three-dimensional (3D) printed provisional resins. A 3-unit fixed partial denture (FPD) preparation was done on ideal model irrespective to 44-46. The Model was scanned and a 3-unit FPD was designed using 3-shape software. The STL file was transferred to two different 3D printers - Sprintray digital light processing (DLP) and Formlabs stereolithography (SLA). Eight samples were printed per group (total of 16 samples) using C and B temporary tooth-colored resin and cured according to the manufacturer's instructions. Marginal adaptation was checked for six surfaces per tooth for all the samples using a stereomicroscope. Surface roughness was also calculated for four samples from each group before and after polishing (pumice slurry + rouge and cotton buff) using a contact profilometer. The mean maximum marginal gap overall, was seen for the DLP group on the mesiobuccal surface of the first premolar, i.e., 178.8 ± 8.35 μm, while the minimal marginal gap was seen for the SLA group on the mesiolingual surface of first molar - 32.5 ± 7.07 μm. Furthermore, all the DLP samples showed a statistically significant higher mean marginal gap as compared to SLA samples (P < 0.005). All the samples showed surface roughness within the acceptable range. There was a statistically significant difference noted in Rz (roughness depth) before and after polishing (P < 0.05). 3D printed temporary resin FPD via SLA showed a much better marginal adaptation (49.6 μm mean marginal gap for 46 and 106.8 μm for 44) as compared to those printed via DLP (101.8 μm mean marginal gap for 46 and 157.5 μm for 44). All the samples showed an acceptable surface roughness. 3D printed temporaries have shown good marginal fit and adaptation and are a viable choice in patients where temporaries has to be given for long term before a final prosthesis can be fabricated (especially for full mouth rehabilitations).

Comparative Study of the Effectiveness of Laboratory-Formulated Polishing Pastes for Two CAD/CAM Ceramic Restorative Materials.

To evaluate the effect of different polishing pastes with different particle sizes on the surface finish of two different CAD/CAM ceramics. A total of 128 specimens were prepared of two CAD/CAM ceramics: lithium disilicate (12.4×14.5×2 mm) and monolithic zirconia (17.5 × 12.5 × 2.5 mm). They were divided randomly into 8 groups according to surface treatment (n = 8). Group 1 (control) was left as received after crystallization or sintering with no further surface treatment; Group 2 (glazed); Group 3 (positive control), where specimens were polished using standardized surface treatment (medium grit silicon carbide discs, rubber cup and pumice slurry, then rubber cup and toothpaste). For groups 4 to 8, in addition to silicon carbide and pumice slurry polishing, specimens were further polished using a diamond paste (DP), and polishing pastes of microzirconia (MZ), nanosilica (NS), nanodiamond (ND), and nanozirconia (NZ), respectively. Surface roughness (Ra ) was measured using noncontact profilometer. The mean values were compared using ANOVA and Post Hoc Tukey's test (α = 0.05). Specimens' surfaces were studied using a scanning electron microscope (SEM). Positive control group and MZ exhibited significant Ra of lithium disilicate compared to control (p ˂ 0.001), glazed (p = 0.001), DPs (p = 0.002), NS (p ˂ 0.001), ND (p ˂ 0.001), and NZ (p = 0.002). In the case of zirconia, positive control showed a significantly higher Ra compared to all other groups (p ˂ 0.001). No statistical difference was found between all other polishing techniques (positive control, glazed, DPs, NS, ND, MZ, and NZ) (p > 0.05). Polishing with ND, NZ, and NS lab-formulated pastes produced surfaces with comparable smoothness to control and glazed specimens for lithium disilicate and zirconia ceramic materials.

Assessment Of Tensile Bond Strength Of Ceramic Restoration Material Comparing Two Immediate Dentin Sealing Protocols

ABSTRACT Aim: The aim of this study was to evaluate the effect of two immediate dentin sealing protocols including sealed dentin surface refreshment with air abrasion versus sealed dentin surface refreshment with pumice on tensile bond strength of ceramic restoration material. Materials and methods: Twenty extracted human molars were used. The prepared teeth were randomly divided into two groups according to the surface refreshment method into group (C): Air abrasion using Cojet and group (P) using pumice slurry. Twenty ceramic discs were sliced into standard thickness of 2mm ceramic slices. The teeth were immediately sealed using single bond universal adhesive it was then covered using a layer of provisional filling material directly after cutting. The provisional filling was then removed and dentin was cleaned using either airborne-particle abrasion (CoJet, 3M ESPE) (Group (C) or Pumice (group (P). The specimens in each group were then thermo-cycled and tensile bond strength test was done, using Universal Testing Machine. One-way ANOVA was used to study the effect of different tested variables and their interaction. Results: Samples done using air abrasion with Cojet, showed higher tensile bond strength than those using pumice. Conclusions: Immediate dentin sealing treatment would be recommended within high tensile stresses, when surface refreshment done by air abrasion to the tooth structure.

Effect of Different Cleansing Protocols on Bond Strength of Composite Resin to Dentin Contaminated with Hemostatic Agent: An In Vitro Study.

Objectives:Inadequate removal of the hemostatic agent can adversely affect the bond strength of restorations to the tooth structure. This study aimed to assess the effect of different cleansing protocols on the shear bond strength (SBS) of an etch-and-rinse adhesive to dentin contaminated with aluminum chloride hemostatic agent.Materials and Methods:In this experimental study, the mid-coronal dentin of 96 premolars was exposed. They were contaminated with a hemostatic agent (ViscoStat Clear) and then randomly divided into 7 groups (n=12). One group served as the control. The groups underwent various cleaning methods as follows: water spray, aluminum oxide particles (27μ diameter), a slurry of pumice with water, GC dentin conditioner (GCDC), sodium hypochlorite 2% (SHC), and chlorhexidine 2% (CHX). Composite cylinders were then fabricated and bonded to the surfaces using Scotchbond Multi-Purpose etch-and-rinse bonding agent. After thermocycling (10,000 cycles), the SBS was measured using a universal testing machine. Data were analyzed using one-way analysis of variance (ANOVA) and Tukey HSD (honestly significant difference) test, and the significance level was set at 0.05.Results:The SBS of the groups was significantly different (P=0.036). The SBS was the highest in the CHX and SHC groups, and the lowest SBS was related to the control group and GCDC groups. The difference between other groups was not significant (P=0.996).Conclusion:CHX and SHC yielded the highest bond strength among the tested modalities for cleansing the ViscoStat Clear from the tooth surface.

Evaluation of Marginal Microleakage and Depth of Penetration of Different Materials Used as Pit and Fissure Sealants: An In Vitro Study.

ABSTRACTObjectiveFissure sealants hold a great significance in the preclusion of inception of caries process. The present in vitro study assesses the marginal sealing ability and penetration depth of various dental products used as pit and fissure sealants.Study designSixty freshly extracted human non-carious premolars were arbitrarily categorized into four groups of 15 samples. Prophylaxis of occlusal surfaces of sample teeth was done with pumice slurry and sealant was applied. Later, the teeth underwent thermocycling and immersion in 5% methylene blue for 24 hours. Sectioning of teeth samples was done buccolingually and they were analyzed under stereomicroscope.Statistical analysis usedNonparametric tests Kruskal–Wallis and Mann–Whitney were applied to carry out microleakage comparison. The percentage penetration depth was compared using the one-way analysis of variance (ANOVA) test. Tukey's post hoc test was applied for multiple analogies.ResultsHighest microleakage was seen in glass ionomer-based sealant followed by flowable composite and least for classical sealant. Flowable nanocomposite gave comparable results with that of the classical sealant. No statistical difference was found with respect to depth of penetration between different tested materials.ConclusionFlowable nanocomposite can be considered as a promising substitute for sealing fissures and thus can be endorsed to caries-susceptible pediatric patients.How to cite this articleButail A, Dua P, Mangla R, et al. Evaluation of Marginal Microleakage and Depth of Penetration of Different Materials Used as Pit and Fissure Sealants: An In Vitro Study. Int J Clin Pediatr Dent 2020;13(1):38–42.

Case report: A novel, fixed chairside space maintainer

Introduction: To prevent the dental arch deficiency after untimely loss of primary teeth, a space maintainer is employed. Space maintainers currently in use like band and loop are considered a non-aesthetic appliance. Light Cured Acrylic Resins LCAR are commonly utilized in dental practice. They provide the essential mechanical and physical properties with the necessary characteristics to be used in diverse functions in dentistry. Aim: To provide an aesthetic alternative space maintainer after premature extraction of second primary molar. Case Description: An eight-year-old healthy boy reported with a recently missing lower left second primary molar. A pink color sheet of LCAR Triad® VLC (Custom Tray) product was used to construct a space maintainer. After complete examination, full arch isolation was performed using rubber dam and suction. Both the abutment teeth were cleaned with pumice slurry and then etched with 35% orthophosphoric acid for 30 seconds for primary first molar and 20 seconds for the permanent first molar. The teeth were rinsed, air-dried, and wetted with an adhesive that was light-cured for 20 seconds. A thin layer of flowable composite was applied to the buccal surfaces of the abutment teeth without light-curing it. The cut length of LCAR was placed over the flowable composite extending from the buccal aspect of permanent first molar to buccal aspect of the primary second molar. The ends of the LCAR were adapted to the teeth surfaces with a plastic instrument. The composite and LCAR was light-cured for 2 minutes. for each end of LCAR.Conclusion: This case report showed that the Light Cure Acrylic Resin space maintainers can be a new alternative to the traditionally fixed space maintainers used in pediatric dentistry.

INFECTION CONTROL PRACTICES

Objectives: The aim of this study was to assess the knowledge and infection control practices among private dental laboratories in Karachi. Study Design: Cross sectional study. Setting: Private Dental Laboratories of Karachi. Period: 01st September 2017 to 01st February 2018. Materials and Methods: A pre structured questionnaire comprised of 09 questions regarding infection control was used to collect the data. A total 35 questionnaires were given to dental technicians. 29 questionnaires were obtained out of 35 distributed (response rate: 83%). Statistical Package for the Social Sciences (SPSS) version 17.0 was used for data analysis. Results: Gloves were not worn by 76% of respondents while receiving the clinical items. Protective eyeglasses and protective face shield were not worn by 38% and 13% of respondents respectively during laboratory work. Few 13% of respondents were vaccinated against the hepatitis b virus. Clinical items were disinfected by 17% of respondents if not disinfected by dental clinic. Laboratory work was not disinfected by 90% of respondents before sending to clinic. Pumice slurry and water of pressure pot were changed by 6% and 6% respectively. Regarding infection control measure impose financial burden, 83% of respondents were agreed. Conclusion: The knowledge and practices of infection control were poor and below acceptable standards in private dental laboratories.

The effect of resin cement type and cleaning method on the shear bond strength of resin cements for recementing restorations.

PURPOSEThis laboratory study assessed the effect of different dentin cleaning procedures on shear bond strength of resin cements for recementing prosthesis.MATERIALS AND METHODS4 × 4 flat surface was prepared on the labial surface of 52 maxillary central incisors. Metal frames (4 × 4 × 1.5 mm) were cast with nickel-chromium alloy. All specimens were randomly divided into 2 groups to be cemented with either Panavia F2.0 (P) or RelyX Ultimate (U) cement. The initial shear bond strength was recorded by Universal Testing Machine at a crosshead speed of 0.5 mm/min. Debonded specimens were randomly allocated into 2 subgroups (n = 13) according to the dentin cleaning procedures for recementation. The residual cement on bonded dentin surfaces was eliminated with either pumice slurry (p) or tungsten carbide bur (c). The restorations were rebonded with the same cement and were subjected to shear test. Data failed the normality test (P < .05), thus were analyzed with Mann Whitney U-test, Wilcoxon signed rank test, and two-way ANOVA after logarithmic transformation (α = .05).RESULTSThe initial shear bond strength of group P was significantly higher than group U (P = .001). Pc and Uc groups presented higher bond strength after recementation compared to the initial bond strength. However, it was significant only in Pc group (P = .034).CONCLUSIONThe specimens recemented with Panavia F2.0 provided higher bond strength than RelyX Ultimate cement. Moreover, a tungsten carbide bur was a more efficient method in removing the residual resin cement and increased the bond strength of Panavia F2.0 cement after recementation.

The Shear Bond Strengths of Composite Bonded to Dentine Following Treatment with Two Dentine Occluding Desensitizing Toothpastes

Aim: This study determined whether prior brushing with desensitizing toothpastes (Sensodyne Rapid Relief and Colgate Pro-Relief) affected the shear bond strengths of composite to dentine surfaces after appropriate use of two different dentine bonding agents (SingleBond and PQ-1). Materials and Methods: Sixty caries free molar teeth were cleaned, disinfected and embedded in individual cylinders of polymethylmethracyrlate. The occulsal surfaces were flattened to expose dentine and finished down with 600 grit silicone carbide paper. The teeth were randomly divided into six groups of 10 teeth each. Two groups served as control where dentine surfaces were brushed with pumice slurry. Of the remaining 4 groups, 2 groups were brushed with Sensodyne Rapid Relief and 2 groups brushed with Colgate Pro-Relief. The dentine surfaces were brushed to simulate 2 weeks of twice-daily toothpaste use. The specimens in each of the control groups and experimental groups were subjected to dentine bonding procedures (Single Bond or PQ-1), and application of hybrid composite resin (Z-250) according to the manufacturer’s instructions. A universal material testing machine, with a cross head speed of 0.05 mm/min was used to determine shear bond strengths. Results: Mean shear bond strengths ranged from 5.71 MPa (Colgate pretreatment, composite bonded with Single Bond) to 9.07 MPa (Sensodyne pretreatment, composite bonded with Single Bond). Results showed neither of the main effects, of toothpaste type or bonding agent were significant (p > 0.05) but their interaction was (F = 4.25, p = 0.02). Post hoc analysis showed that teeth brushed with the Sensodyne group, treated with the unfilled dentine bonding agent had a significantly higher bond strength than those treated with the filled dentine bonding agent. Conclusion: The desensitizing toothpastes that use the mechanism of occlusion of open dentinal tubules in the preliminary management of tooth sensitivity should not have an adverse effect on future restorative treatment modalities.

Effect of orthodontic debonding and adhesive removal on the enamel - current knowledge and future perspectives - a systematic review.

After orthodontic treatment, brackets are debonded and residual adhesive is removed, causing iatrogenic enamel damage. The aim of this study was to review the methods of orthodontic adhesive removal, find clear evidence, and provide a rationale for this procedure.A literature search was performed in PubMed, Dentistry and Oral Sciences, Scopus, Cochrane, Google, and Google Scholar using keywords: orthodontic adhesive removal, orthodontic debonding, orthodontic clean-up. Studies concerning human enamel roughness or loss from debonding and adhesive removal were considered. Forty-four full-text articles were analyzed and 3 were rejected after detailed reading; finally 41 papers were included.Fifteen qualitative studies, 13 studies based on indices of enamel surface, and 13 quantitative studies were found. No meta-analysis could be performed due to a lack of homogenous quantitative evidence. The most popular tools were tungsten carbide burs, which were faster and more effective than Sof-Lex discs, ultrasonic tools, hand instruments, rubbers, or composite burs. They remove a substantial layer of enamel and roughen its surface, but are less destructive than Arkansas stones, green stones, diamond burs, steel burs, and lasers. Multi-step Sof-Lex discs and pumice slurry are the most predictable enamel polishing tools.Arkansas stones, green stones, diamond burs, steel burs, and lasers should not be used for adhesive removal. The use of tungsten carbide bur requires multistep polishing. Further efforts should be made to find tools and methods for complete removal of adhesive remnants, minimizing enamel loss and achieving a smooth surface.

Microbial Contamination of Pumice Powder and Slurry in Dental Laboratories of Hamadan

Background: Using contaminated pumice in polishing process of dental prostheses may result in cross-contamination of dentists, laboratory technicians, and patients. Objectives: This study aimed to determine the presence and level of microbial contaminants in pumice powder and slurry used in dental laboratories of Hamadan city. Materials and Methods: Forty specimens, including 20 pumice powders and 20 pumice slurries were collected from 10 randomly selected dental laboratories and inoculated onto selective and non-selective media in order to count the total colony-forming units (CFU). Isolated fungi and bacteria were identified using Gram-stain and deferential diagnostic tests. Results: Results of this study showed 85% contamination rate for pumice powders and 100% for pumice slurries. Frequencies of Grampositive and Gram-negative bacteria isolated from the powders were 68% and 32% respectively. For the slurries the frequencies were 61% Gram-positive and 39% Gram-negative. Organisms detected in pumice powders composed of Staphylococcus epidermidis, E. coli, Acinetobacter, B. cereus, Enterobacter, Candida, and diphtheroids. Organisms detected in pumice slurries included Staphylococcus epidermidis, E. coli, Citrobacter, S. aureus, Enterobacter, B. cereus, B. proteus, Candida, and diphtheroids. Conclusions: According to this study, pumice powder and slurry used in dental laboratories of Hamadan are contaminated. Therefore, the Laboratory staff should be aware of the hazards posed by the presence of pathogens in dental laboratories

Microbial contamination of pumice used in dental laboratories

Dental appliances as well as sending and receiving prosthesis from laboratories are potential sources of cross-contamination for technicians, dentists, patients and can transmit different infectious agents as well. This study was conducted to determine the types of the microorganisms in pumice powder and pumice slurry used in dental laboratory in order to evaluate necessary disinfection control procedure in the dental settings. Twenty-four active dental laboratories of Khorram Abad participated in our study. Samples were randomly collected from prosthesis polishing containers in sterilized condition and were immediately sent to microbiology laboratory. Specimens were cultured on selective bacterial and fungal media in order to determine the microorganisms. Both oral and non-oral bacteria were recovered from pumice samples as follows: Staphylococcus aureus (15.4%), Streptococcus viridance (10.8%), Bacillus cereus (18.7%), Pseudomonas aeruginosa (12.8%), Diphtheriods (7.3%), Enterobacter cloace (4.3%), Escherichia coli (13.1%), Klebsiella pneumonia (5.4%), and Acinetobacter spp. (12.2%). The isolated fungi included Candida albicans (36.7%), other yeasts (17.3%), Fusarium spp. (13.8%), Aspergilus spp. (22.4%) and Penicillium spp. (9.8%). This study showed that polishing pumices in the form of powder or slurry were contaminated with different oral and non-oral bacteria and also fungi. Therefore, the chance of cross-contamination still severely exists, and measures should be conducted to prevent the contamination of predisposed people such as technicians, dentists and patients.

An in vitro investigation to compare the surface roughness of auto glazed, reglazed and chair side polished surfaces of Ivoclar and Vita feldspathic porcelain

The change in surface roughness after different surface finishing techniques has attracted the attention of several prosthodontists regarding wear of opposing teeth or restorative material and the strength; plaque retention and appearance of the restoration. However, there is considerable controversy concerning the best methods to achieve the smoothest and strongest porcelain restorations after chair side clinical adjustments. The purpose of this in vitro study was to compare the average surface roughness of a self-glazed surface, a chair side polished surface and a reglazed surface of ceramic. Two feldspathic porcelain, namely VITA VMK94 (Vita Zahnfabrik, Bad Sachingen, Germany) and IVOCLAR CLASSIC (Vivadent AG, FL-9494 Schaan, Liechtenstein) were selected to fabricate 20 specimens of each in the shape of shade guide tabs. A medium-grit diamond rotary cutting instrument was used to remove the glaze layer, and then the surface of half the specimens were re-glazed and the other half were polished using a well-defined sequence of polishing comprising of: Shofu porcelain polishing system, White gloss disc/polishing wheel, Silicone cone with diamond polishing paste and finally with small buff wheel with pumice slurry. The surface roughness (Ra) (μm) of the specimens was evaluated using a profilometer and scanning electron microscope. The data were statistically analyzed by using Student's t test. The results had shown that there is no statistically significant difference both quantitatively and qualitatively, between the surface roughness of reglazed and chair-side polished surface. In addition, both reglazed and chair-side polished surfaces are better than the autoglazed surface. Within all the groups, there is no significant difference between companies. Polishing an adjusted porcelain surface with the suggested sequence of polishing will lead to a finish similar to a re-glazed surface. Therefore chair-side polishing can be a good alternative to reglazing for finishing adjusted porcelain surface.

Comparison of six different methods of cleaning and preparing occlusal fissure surface before placement of pit and fissure sealant: An in vitro study

The purpose of this in vitro study was to evaluate and compare the microleakage of pit and fissure sealants after using six different preparation techniques: (a) brush, (b) pumice slurry application, (c) bur, (d) air polishing, (e) air abrasion, and (f) longer etching time. The study was conducted on 60 caries-free first premolars extracted for orthodontic purpose. These teeth were randomly assigned to six groups of 10 teeth each. Teeth were prepared using one of six occlusal surface treatments prior to placement of Clinpro" 3M ESPE light-cured sealant. The teeth were thermocycled for 500 cycles and stored in 0.9% normal saline. Teeth were sealed apically and coated with nail varnish 1 mm from the margin and stained in 1% methylene blue for 24 hours. Each tooth was divided buccolingually parallel to the long axis of the tooth, yielding two sections per tooth for analysis. The surfaces were scored from 0 to 2 for the extent of microleakage. Results obtained for microleakage were analyzed by using t-tests at sectional level and chi-square test and analysis of variance (ANOVA) at the group level. The results of round bur group were significantly superior when compared to all other groups. The application of air polishing and air abrasion showed better results than pumice slurry, bristle brush, and longer etching time. Round bur group was the most successful cleaning and preparing technique. Air polishing and air abrasion produced significantly less microleakage than traditional pumice slurry, bristle brush, and longer etching time.

Comparative assessment of sodium chloride, sodium bicarbonate dissolved in vinegar and hydrogen peroxide as bleaching agents to reduce intrinsic dental stains: In vitro study

Purpose : With the increasing concern for aesthetics, dentists are working hard to give their patient what is called the 'perfect smile'. Discolouration of teeth is an aesthetic problem, which requires effective treatment. Bleaching is the simplest, common most effective treatment to reduce the stains, but unfortunately which is not within the reach of all individuals. Hence an attempt has been made to evaluate the effectiveness of various indigenous agents like sodium chloride, sodium bicarbonate dissolved in vinegar containing 4% acetic acid and hydrogen peroxide, as bleaching agents to reduce intrinsic dental stains. Materials and Methods : Forty extracted premolars having mild degree of dental fluorosis were selected and thoroughly cleaned with pumice slurry. All the polished 40 teeth were randomly divided into 4 groups each containing 10 teeth. Bleaching was performed on ten teeth per group by immersing them in solutions containing either 1.5% hydrogen peroxide, 10% w/v of sodium chloride + vinegar containing 4% acetic acid, 10% w/v of sodium bicarbonate + vinegar containing 4% acetic acid or distilled water for 5 minutes each. The intrinsic colour of teeth was measured with a spectrophotometer using the standard L*a*b* colour scale and the shade was evaluated at day 0, 7, 14 and 21. Results: Compared to baseline tooth colour, hydrogen peroxide and sodium chloride dissolved in vinegar were significantly effective in removing the intrinsic tooth stain ( P Conclusions: Sodium chloride dissolved in vinegar was more effective at reducing intrinsic tooth stain than sodium bicarbonate dissolved in vinegar.

The effect of mechanical and chemical polishing techniques on the surface roughness of denture base acrylic resins

Smooth polished surface of dental prostheses is important to prevent bacterial colonization and plaque accumulation. The acrylic base of prosthodontic appliances needs to be adjusted by grinding which often alters the surface of the denture base. It is therefore important to know how different polishing techniques affect surface roughness of acrylic resin. The aim of this study was to evaluate the effect of mechanical polishing (MP) and chemical polishing (CP) on the surface roughness of heat cured (HC) and auto cured (AC) denture base acrylic resins. Sixty acrylic resin specimens (30×15×3mm) were made for each of the two types of acrylic resins. Thirty HC specimens received mechanical conventional lathe polishing using cone with pumice slurry and soft brush with chalk powder. The other thirty HC specimens received chemical polishing by immersing in methyl-methacrylate monomer heated to 75°C±1°C for 10s. The sixty AC specimens received mechanical and chemical polishing in the same manner. Surface roughness was measured using surface analyzing instrument in microns. The data were statistically analyzed by two-way analysis of variance (ANOVA) followed by post hoc Tukey's test (α=0.05). THE SURFACE ROUGHNESS MEAN IN MICRONS IN ORDER OF DECREASING VALUES WERE: CP-HC: 1.4132μm; CP-AC: 1.3494μm; MP-AC: 0.7364μm and MP-HC: 0.6333μm. Two-way ANOVA revealed that the MP-HC was significantly different from CP-HC and CP-AC (P<0.05). The MP-AC is also significantly different from CP-HC and CP-AC (P<0.05). There was no significant difference between MP and CP of HC and AC acrylic resin groups. It can be concluded that MP produced significantly smoother surfaces than CP. The surface roughness obtained by MP was not influenced by acrylic resin type where as this was not true for CP.