Comparing cytocompatibility of two fluoride-containing solutions and two resin-based restorative materials-a pilot study.

Background: Cytocompatibility should always be considered, especially if the surface of treated carious lesions is close to soft tissue or is accidentally exposed to the oral soft tissue by the clinician. Methods: The aim of the present study was to compare the cytocompatibility of two fluoride-containing liquids and two resin-containing restorative materials with buccal mucosa fibroblasts. The fluoride-containing materials were silver diamine fluoride and water-based silver fluoride. Results: The statistical analysis was completed by comparing the positive control growth of the buccal mucosa fibroblasts to the growth of cells exposed to various materials. The one-way ANOVA with Tukey's HSD result was completed. All the assessed materials compared to the control wells for both the 24 and 48 h time intervals indicated a significant cytocompatibility result, except for the test wells with Stela (SDI) at the 24 h time interval. There was no significant difference between the step 2 liquids and the two dental materials in cytocompatibility at the 24 h interval. All four materials indicated no significant differences between the cytocompatibility of any dental materials for 48 h. Conclusion: The cytocompatibility assessment for Riva Star and Riva Star Aqua with the direct method in a full dispensing drop is not viable for step 1 of the fluoride-containing liquids. The use of Stela Light Cure is a suitable material that will be in contact with buccal mucosa as it showed potential for increased cytocompatibility compared to Riva Light Cure. Riva Star Aqua is more cytocompatible than Riva Star.

Penetration of SDF and AgF from the infected dentine towards the unaffected tooth structure.

Background: The use of SEM-EDS line scan analysis to evaluate the movement of ions from dental materials towards the tooth structure and the concept of ion movement is well established. This analysis technique was used to determine the ion movement of two commercially available silver- and fluoride-containing products. Methods: This study aimed to compare the elemental analysis of primary molar teeth treated with silver diamine fluoride (SDF) and water-based silver fluoride (AgF) and to analyse the penetration of SDF and AgF from the infected dentine towards the healthy dentine. The teeth were cleaned from debris and contaminants off the roots and stored until use. A total of 15 primary molars with large active cavitated lesions, not extending into the pulp (specimens), were divided into three test groups: silver diamine fluoride (SDF) (n = 5), water-based silver fluoride (AgF) (n = 5), and deionised water (W) (n = 5) as the control group. The teeth were sectioned, embedded, and received SEM-EDS line scans. The line scan had a total length of 82.65 µm. The visible end of the infected dentine and the start of the more affected dentine were chosen as the starting point to ensure that the infected caries' line distribution towards the affected dentine's transition area was as standardized as possible. Therefore, the infected dentine length of the scan was 22.80 µm (8 scan points of 2.85 µm apart), and the affected dentine, including the healthy dentine, was 59.8 µm (21 scan points). The SEM-EDS line scan from each specimen determined the average fluoride, iodide, and silver weight percentage for that specimen. Results: The 15 sample SEM-EDS line scans were used to determine the average ion movement in wt%. The Kruskall-Wallis test and Tukey's HSD test were completed at a p < 0.05. SDF and AgF presented no significant fluoride movement in terms of the weight percentage. There was, however, significantly more fluoride movement from infected caries to the healthy dentine with SDF and AgF (p = 0.0010053) compared to the control specimens treated with deionised water. There was no significant difference between SDF and AgF for the movement of the iodide (p = 0.5953) and silver (p = 0.3708) from infected caries to the healthy dentine. Conclusion: SDF and AgF easily penetrated through infected caries and affected tooth structure to the healthy dentine for the line scan of 82.65 µm. There was no significant difference between SDF and AgF for the movement of ions within the infected dentine nor in the affected/healthy dentine.

Cuspal deflection of teeth restored with bulk fill flowable composite resins, with and without fiber-reinforcement and evaluated by Micro-computed Tomography.

Polymerisation shrinkage of composite resins is a clinical challenge which has been well documented in the literature. Many studies investigating polymerisation shrinkage stress measure cuspal deflection, which is a manifestation of this stress. The introduction of flowable bulk-fill composite (BFRBC) materials has streamlined the restorative process, though the shrinkage and cuspal deflection from these BFRBCs has not been compared with regards to its use with polyethylene fibers (Ribbond fibers). The authors describe a method to measure the cuspal deflection of flowable BFRBCs placed in cavities of standardised dimensions at distinct steps of the restorative process, with and without fiber-reinforcement and using x-ray micro-computed tomography. Co-ordinate points are established on the buccal and lingual aspects of scanned specimens using the Volume Graphics VG Studio max 3.2.5 (Hiedelberg, Germany 2018) software. The system allows for these landmarks to be established across each scan (of the same tooth), ensuring standardization of each specimen. Further anatomical points are used to enable analysis. Comparison of angles generated across these points determines the extent of cuspal deflection.•A method of measuring the cuspal deflection of composite resins is proposed.•Experimental procedures are provided.•Data analysis methods are outlined.

Correction: Noordien et al. In Vivo Study of Aerosol, Droplets and Splatter Reduction in Dentistry. Viruses 2021, 13, 1928.

There was an error of omission in the original publication [...].

Human examination and artificial intelligence in cephalometric landmark detection-is AI ready to take over?

OBJECTIVES: To compare the precision of two cephalometric landmark identification methods, namely a computer-assisted human examination software and an artificial intelligence program, based on South African data. METHODS: This retrospective quantitative cross-sectional analytical study utilized a data set consisting of 409 cephalograms obtained from a South African population. 19 landmarks were identified in each of the 409 cephalograms by the primary researcher using the two programs [(409 cephalograms x 19 landmarks) x 2 methods = 15,542 landmarks)]. Each landmark generated two coordinate values (x, y), making a total of 31,084 landmarks. Euclidean distances between corresponding pairs of observations was calculated. Precision was determined by using the standard deviation and standard error of the mean. RESULTS: The primary researcher acted as the gold-standard and was calibrated prior to data collection. The inter- and intrareliability tests yielded acceptable results. Variations were present in several landmarks between the two approaches; however, they were statistically insignificant. The computer-assisted examination software was very sensitive to several variables. Several incidental findings were also discovered. Attempts were made to draw valid comparisons and conclusions. CONCLUSIONS: There was no significant difference between the two programs regarding the precision of landmark detection. The present study provides a basis to: (1) support the use of automatic landmark detection to be within the range of computer-assisted examination software and (2) determine the learning data required to develop AI systems within an African context.

Prevalence of oral mucosal lesions in human immunodeficiency virus-infected children attending the Pediatric Infectious Diseases Clinic in Cape Town.

OBJECTIVE: Investigation of the prevalence of oral mucosal lesions in human immunodeficiency virus (HIV)-infected children undergoing highly active antiretroviral therapy (HAART). MATERIALS AND METHODS: Cross-sectional study of 66 HIV seropositive children, comprised of 28 (42.4%) females and 38 (57.6%) males (average age of 6 years). Study participants all required data regarding CD4+ T-helper cell counts and the viral load. All participants underwent an orofacial clinical examination by calibrated clinicians. Associations between the presence of oral mucosal lesions, CD4+ cell counts, and viral load were analyzed using Poisson regression. RESULTS: The prevalence of oral manifestations was detected in 21 children (31.8%). Oral lesions were detected in 16 children with viral load copies <50 cells/mm3 and 22 children with CD4+ counts >500 cells/mm3 . Predominant lesions identified included angular cheilitis (36.7%), candidiasis (13.3%) and atypical oral ulcers (13.3%). The presence of one lesion was the most prevalent represented by 19 children. Oral lesions in relation to the CD4+ counts >500 resulted in; 14 children with one oral lesion, 5 with two lesions and 3 with three oral mucosal lesions. The other half of this CD4+ count patient group presented with no oral mucosal lesions. Oral lesions in relation Viral load copies <50 resulted in; 9 children with one oral lesion, 3 with two oral mucosal lesions and 4 with three oral mucosal lesions. The other half of this Viral load patient group presented with no oral mucosal lesions. No significant correlations were established between the presence of oral mucosal lesions and low CD4+ counts (p = 0.715) nor with high viral load counts (p = 0.638). CONCLUSION: HIV-related oral mucosal lesions still presented in the participants despite management with HAART. Based on the results, CD4+ counts and viral load does not appear to be suitable markers of orofacial involvement in children.

The Photobiomodulation Effect of 940nm Laser Irradiation on Enterococcus faecalis in Human Root Dentin Slices of Varying Thicknesses.

Introduction: An increase in dentine thickness could result in an inadequate depth of laser energy penetration. This study aimed to evaluate the effect of a 940 nm laser on Enterococcus faecalis through varying thicknesses of human root dentin slices. Methods: Thirty-five dentin slices of root dentin with thicknesses ranging between 500 and 3000 µm were produced. Six experimental groups (500, 1000, 1500, 2000, 2500, and 3000 µm (n=5 each) were lased and the seventh, non-lased group served as the positive control with a dentine thickness of 2000 µm. The slices were inoculated with 2 µL of E. faecalis suspension of 1.5 × 108 E. faecalis cells/mL. All the lased slices were lased from the opposing side of the inoculation. A non-initiated 200 µm bare end fibre at the power of 1 W, in a continuous wave was used. Four doses of laser irradiation of 5 seconds with a side to side movement with the tip held at a 5º angle to the dentine slice were performed. The colony-forming units of E. faecalis were determined and the bacterial photobiomodulation effect analysed using one-way ANOVA with a Bonferroni and Holm post hoc test at a significance level of P > 0.05. Results: There were statistical differences between the dentin slices of 500, 1000, and 1500 µm treated with the laser compared to the positive control (P < 0.01). However, there were no statistical differences between the lased 2000 and 2500 µm slices compared to the positive control. There was significantly more photobiomodulation of the E. faecalis for the dentine slices of 3000 µm than the positive control (P < 0.01). Conclusion: Laser treatment through dentine slices of 2000 µm and thinner significantly reduced bacterial growth. The photobiomodulation effects started to occur in dentine slices thicker than 2500 µm compared to the positive control.

In Vivo Study of Aerosol, Droplets and Splatter Reduction in Dentistry.

Oral health care workers (OHCW) are exposed to pathogenic microorganisms during dental aerosol-generating procedures. Technologies aimed at the reduction of aerosol, droplets and splatter are essential. This in vivo study assessed aerosol, droplet and splatter contamination in a simulated clinical scenario. The coolant of the high-speed air turbine was colored with red concentrate. The red aerosol, droplets and splatter contamination on the wrists of the OHCW and chests of the OHCW/volunteer protective gowns, were assessed and quantified in cm2. The efficacy of various evacuation strategies was assessed: low-volume saliva ejector (LV) alone, high-volume evacuator (HV) plus LV and an extra-oral dental aerosol suction device (DASD) plus LV. The Kruskal-Wallis rank-sum test for multiple independent samples with a post-hoc test was used. No significant difference between the LV alone compared to the HV plus LV was demonstrated (p = 0.372059). The DASD combined with LV resulted in a 62% reduction of contamination of the OHCW. The HV plus LV reduced contamination by 53% compared to LV alone (p = 0.019945). The DASD demonstrated a 50% reduction in the contamination of the OHCWs wrists and a 30% reduction in chest contamination compared to HV plus LV. The DASD in conjunction with LV was more effective in reducing aerosol, droplets and splatter than HV plus LV.

A Systematic Review on the Efficacy of Vaporized Hydrogen Peroxide as a Non-Contact Decontamination System for Pathogens Associated with the Dental Environment.

Aerosol generation and a wide range of pathogens originating from the oral cavity of the patient contaminate various surfaces of the dental clinic. The aim was to determine the efficacy of vaporized hydrogen peroxide fogging on pathogens related to the dental environment and its possible application in dentistry. PICOS statement (Population, Intervention, Comparison/Control, Outcome and Study design statement) was used in the review. Six electronic databases were searched for articles published from 2010 to 2020. Articles written in English reporting vaporized hydrogen peroxide on pathogens deemed to be relevant to the dental environment were assessed. The quality of the studies was assessed using the risk-of-bias assessment tool designed for the investigation of vaporized hydrogen peroxide application in dentistry. A total of 17 studies were included in the qualitative synthesis. The most commonly reported single bacterial pathogen was Methicillin-resistant Staphylococcus aureus in five studies, and the viruses Feline calicivirus, Human norovirus, and Murine norovirus were featured in three studies. The results of the studies reporting the log kill were sufficient for all authors to conclude that vaporized hydrogen peroxide generation was effective for the assessed pathogens. The studies that assessed aerosolized hydrogen peroxide found a greater log kill with the use of vaporized hydrogen peroxide generators. The overarching conclusion was that hydrogen peroxide delivered as vaporized hydrogen peroxide was an effective method to achieve large levels of log kill on the assessed pathogens. The hydrogen peroxide vapor generators can play a role in dental bio-decontamination. The parameters must be standardized and the efficacy assessed to perform bio-decontamination for the whole clinic. For vaporized hydrogen peroxide generators to be included in the dental bio-decontamination regimen, certain criteria should be met. These include the standardization and efficacy assessment of the vaporized hydrogen peroxide generators in dental clinics.

A Call for Action to Safely Deliver Oral Health Care during and Post COVID-19 Pandemic.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak started just a couple of months ago and it grew rapidly causing several deaths and morbidities. The mechanism behind the transmission of the virus is still not completely understood despite a multitude of new specific manuscripts being published daily. This article highlights the oral cavity as a possible viral transmission route into the body via the Angiotensin converting enzyme 2 receptor. It also provides guidelines for routine protective measures in the dental office while delivering oral health care.

A Scoping Review of Respirator Literature and a Survey among Dental Professionals.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus was discovered in China in late 2019 and subsequently triggered a global pandemic. Dentists, like many other health professionals, are at an increased risk of contracting the virus as they work in close proximity to patients, especially when performing aerosol-generating procedures. Thus, in order for dentists to protect themselves and their patients, it is recommended that practitioners wear filtering facepiece 2 (FFP2) respirators. The prolonged use of these FFP2 respirators has been linked to several side effects. The aim of this paper is to assess the perceived experience associated with N95/FFP2 respirators based on the available literature and data collected through an online survey completed by Italian dental professionals. Articles were included up to May 2020 and literature searches were conducted through The National Library of Medicine, Cochrane Central Register of Controlled Trials, and Embase databases. The search terms included COVID-19, respirators, masks, and discomfort. An online survey was administered to 256 Italian dentists. The results from this survey were in agreement with the available literature. The findings concurred that the prolonged use of respirators was associated with headaches (47.5%), severe exertion and discomfort (50.8%), moderate concentration problems (54.3%), moderate breathing difficulties (63.5%), and consequently, an impaired work ability (85.5%). These findings were not influenced by the number of hours spent wearing the respirator. Despite several side effects, FFP2 respirators are fundamental in protecting dentists and their importance was acknowledged.

Determination of orthodontic bracket and tooth adaptation using an X-ray micro-computer tomography scanner.

The determination of the orthodontic brackets' adaptation to the curvatures of teeth is a difficult topic to study. The complexity arise due to the different designs of their fitting surfaces, margins and curvatures of orthodontic brackets. Teeth on the other hand have variation in their curvatures and the question remains how well an orthodontic brackets truly adapt to the teeth. Previous methods from the literature determined the curvature of teeth through the superimposition of circular templates onto dental plaster models as well as the use of acrylic arcs of various diameters. Here the authors describe a method to compare the curvatures obtained from an industrial X-ray micro-computer tomography scanner and processing software of orthodontic brackets and plaster casts of teeth. Three orthodontic brackets could be assessed by establishing co-ordinate points of proposed standardized landmarks on the orthodontic brackets. These standardized landmarks from each orthodontic bracket can be applied onto the various plaster teeth that was scanned. The adaptation of the three brackets to the various teeth can be compared by looking at their radii and angles that were determined in this method.•The analysis of orthodontic brackets and teeth curvatures have been streamlined on a virtual platform.•Analysis of X-ray micro-computer tomography of tooth curvatures provide a guide to the range of curvatures that orthodontic brackets need to fit.•X-ray micro-computer tomography of orthodontic brackets can enhance the design of the brackets to fit a large array of tooth curvatures.

Oral status of HIV-infected children aged 12 years or younger who attended a Paediatric Infectious Diseases Clinic in Cape Town.

BACKGROUND: Children continue to suffer from the impact of the human immunodeficiency virus-acquired immunodeficiency syndrome (HIV/AIDS) pandemic. In Cape Town, these children receive medical care including antiretroviral therapy from facilities like Tygerberg Hospital's Paediatric Infectious Diseases Clinic. HIV-infected children may experience an increased caries experience when compared with their healthy peers. AIM: The aim of this study was to determine the oral health status of HIV-infected children younger than 12 years receiving antiviral drugs at the Paediatric Infectious Diseases Clinic. DESIGN: A cross-sectional survey was conducted among children aged between 2 and 12 years presenting at this clinic. Caregivers were interviewed to obtain information regarding health seeking behaviour, oral hygiene practices and dietary habits. A single clinician undertook a standardized clinical intraoral examination according to the World Health Organization guidelines, with modifications. RESULTS: Sixty-six children were recruited. A high prevalence of dental caries (78.8%) and an unmet treatment need of 90.4% were recorded among the participants. Most children had never visited the dentist, and those who did had mainly received emergency dental care. CONCLUSION: The high prevalence of severe dental caries in this population highlights the need for oral health awareness and the inclusion of oral health care in the comprehensive care of children with HIV. WHY THIS PAPER IS IMPORTANT TO PAEDIATRIC DENTISTS: The study highlights the importance of collaborating with health professions outside of dentistry. Doctors and nurses are often the first health professionals to come into contact with children with special needs. They should therefore be made aware of the early signs of decay so that these patients can be referred for dental treatment timeously. Holistic management of children with special healthcare needs is essential to improve their overall well-being.

Streptococcus mutans Growth and Resultant Material Surface Roughness on Modified Glass Ionomers.

The present study investigate the optical density of Streptococcus mutans (S. mutans) at 450 nm (OD450 nm) as well as the change in surface roughness of three commercially available chitosan- and nanodiamond-modified glass ionomers. The results indicated that the optical density of S. mutans OD450 nm decreased significantly (p < 0.0001) from 0 h through 2-4 h for each of the control materials. The lowest S. mutans OD450 nm was noted for Fuji IX followed by Ketac Universal. Riva Self Cure had the largest increase in the S. mutans OD450 nm. The control materials and their chitosan/nanodiamond modifications showed significant growth at 6 h compare to the preceding time periods of 2 and 4 h. The materials Fuji IX, Fuji IX modified with 5% Nanodiamonds, Fuji IX modified with 10% Chitosan and Ketac Universal modified with 10% Chitosan performed the best with regard to the bacterial reduction. Only the chitosan modifications showed an increase in the surface roughness after 24 h of exposure to the S. mutans. The chitosan and the nanodiamond modifications provided the best disruption of the S. mutans biofilm formation.

Neutral Sodium Fluoride Gel Uptake of Newly Placed Nanodiamond-modified Glass Ionomers.

PURPOSE: Three commercial restorative glass-ionomer cements (GICs) were modified with 5% and 10 wt/wt% nanodiamond (ND) particles incorporated into the powder of the GICs. The aim of the study was to assess the percentage of surface fluoride increase on different materials, following 2% neutral sodium fluoride gel application (2% NSF). Materials and Methods: The commercial GICs were: FN, Fuji IX GP (GC); KU, Ketac Universal (3M Oral Care); and RSC: Riva Self Cure (SDI). Grade 1 (Plasmachem) nanodiamond was used. Six specimens of each material were prepared using precise powder:liquid ratios. After a 10-min setting time, the GICs were polished. The specimens were randomly divided into two groups: control (group A) and test (group B). The samples were blot dried and group B received the 2% NSF gel for 2 min. The excess was wiped off with gauze and both groups were analyzed with SEM-EDS. Results: Data analysis revealed that all the GICs and their respective ND modifications had a statistically significant surface fluoride percentage increase (p < 0.0001) on the GICs in group B. The addition of ND10% w/w to FN (p < 0.001) and RSC (p = 0.029) resulted in statistically significant increase of surface fluoride percentage. KU remained consistent with no statistically significant increase noted between ND-modified KU and KU in group A or B. Conclusion: The ability of GICs to absorb the 2% NSF gel immediately after finishing of the restoration statistically significantly increases the fluoride percentage of the surface layer.

Comparison of Aerosolized Hydrogen Peroxide Fogging with a Conventional Disinfection Product for a Dental Surgery.

AIM AND OBJECTIVE: The study aimed to determine the efficacy of adding a 12% hydrogen peroxide dry hydrogen peroxide vapor fogger system as an additional layer of infection control in a dental surgery. MATERIALS AND METHODS: A total number of agar plates from the five locations were used during the treatment of the 22 patients (n = 440). During the treatment of each patient, four agar plates (n = 4) were used per location [location 1: X-ray, location 2: the dental arm, location 3: left side desk, location 4: under the foot of the dental chair, location 5: ri ght side desk and (n = 20 for the five locations per patient)]. The control agar plates were incubated after the treatment of the patient was completed period. The test agar plate groups were sprayed with a 70% isopropanol surface disinfectant, or received exposure to an automated 12% hydrogen peroxide fog, or a 70% isopropanol surface disinfectant spray immediately followed by exposure to the automated 12% hydrogen peroxide. RESULTS: One-way ANOVA and Scheffé's method identified significant differences (p < 0.01). Between the control agar plates and the three disinfection methods used a significantly lower colony count was established for colonies recorded in the surgery assessed as a whole, the X-ray unit, and the ri ght side desk. CONCLUSION: The disinfection of dental surgery r equires sufficient time as it not only includes the working surfaces but also various inanimate objects. Surface disinfectant spray followed by hydrogen peroxide decontamination has potential for dental surgery, as the colony-forming units have been r educed further compared to spray alone and even just fog alone for all the various areas of the dental surgery that was assessed. CLINICAL SIGNIFICANCE: The infection control protocols with hydrogen peroxide vapor would ensure the maximum efficacy of the disinfection protocols.

Ion release of chitosan and nanodiamond modified glass ionomer restorative cements.

PURPOSE: Ion release from glass ionomer restorative cements (GICs) plays an important role in GICs. The ion release from chitosan and nanodiamond-modified glass ionomers was assessed. MATERIALS AND METHODS: Three GICs (Fuji IX, Ketac Universal and Riva Self Cure) were modified in the powder phase per weight by adding 5% or 10% of a commercially available chitosan powder (CH) or nanodiamond (ND) powder to the GICs. The specimens with dimensions 4 mm diameter and 6 mm height manufactured from the 15 GIC formulations were allowed to set for 1 hr and subsequently placed in neutral de-ionised water. The released ions were assessed using inductively coupled plasma-mass spectrometer (ICP-MS) to determine the elemental release. Additionally, three different disc-shaped specimens (3 mm in diameter and 1 mm thick) were constructed from each material for scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (SEM-EDS) microanalysis to establish an ion weight percentage. RESULTS: There were no significant differences in the ion release between the control materials for aluminium, silicon and strontium. The ion release from CH and most ND-modified GICs were significantly (p<0.00001) increased compared to the control materials. CH modifications significantly increased the ion release of aluminium, sodium, silicon and strontium for all three control materials (with the exception of the strontium release from Ketac Universal that was modified with 5% chitosan). CONCLUSION: Ion release can be advantageous to tooth structure due to the interaction of chitosan with the GIC chemistry and moisture during maturation. Ion release up to five times greater than the control was noted for some ions.

In Vitro Analysis of Techniques that Alter the Surface Hardness of a Glass Ionomer Restorative Material.

AIM: The aim of this in vitro study was to compare the effect of different manipulation techniques on the surface hardness of ChemFil Rock glass ionomer. MATERIALS AND METHODS: The changes in Vickers surface hardness (VH) of ChemFil Rock were evaluated after the application of five manipulation techniques and compared with one control group (n = 60). The manipulation techniques included: finger pressure set, electronic piezo producing a high frequency set, air piezo producing a low frequency set, heat-set achieved with a curing light and the last technique was a combination of electronic piezo followed by heat-set. Standard set was the control. RESULTS: The average surface hardness for the standard set was 49.5 VH. No statistical differences were demonstrated when the means were compared for finger pressure set (49.2 VH) or the air piezo set (48.49 VH) with standard set. The electronic piezo (54.21 VH) and the heat-set (57.5 VH) had an increased mean surface hardness when compared to other techniques. Heat-set had the highest surface hardness demonstrating a significant statistical difference when compared with standard set, finger pressure set, air piezo set as well as the combination of electronic piezo (p < 0.05). CONCLUSION: The surface hardness of the glass ionomer cement (GIC) material assessed in this study can be predictably improved by applying the heat-set technique. A command set can be achieved with the electronic piezo or the air piezo, however, the surface hardness will only increase with the use of the electronic piezo. CLINICAL SIGNIFICANCE: The clinical advantage of using the air piezo as well as the electronic piezo technique would lie in preventing moisture contamination and dissolution of the GIC due to the command set effect of the ultrasonic vibrations within 15 seconds. The heat technique with the LED curing light will reduce the setting time to 90 seconds.

Variation in the Dispersions of Powder Liquid Ratios in Hand-Mix Glass Ionomers.

BACKGROUND: The Powder/Liquid Ratio (PLR) influence, and the literature regarding the handling and physical properties of Glass Ionomer restorative materials (GIC) were investigated. OBJECTIVE: The objective of the study was to compare the PLR variability and magnitude in hand-mix GICs, as dispensed for clinical use. From the recorded individual powder and liquid weights, additional comparisons could be made by pairing the various "extreme" outer observations in relation to the manufacturer's PLR. STUDY DESIGN: The materials assessed were Ketac Universal Hand-mix (KUH), Riva Self Cure Hand-mix (RSCH) and Fuji IX GP Hand-mix (FIXH). Twenty scoops of powder were paired with twenty drops of liquid, as would be the case in the clinical scenario. Statistical analysis was completed with the Kruskal Wallis H test, Intraclass Correlation (ICC) and straight line regressions with One-way ANOVA and the post-hoc Tukey HSD Test (p<0.05 was considered significant). RESULTS: The powder and liquid observations indicate a lack of consistency in both the powder and liquid dispersions. The volume remained "one drop" but the weights were much lower than the manufacturer's recommended drop weight for some observations, due to air in the liquid drop. The Kruskal-Wallis H test indicated significant differences (p=0.0001) between the three materials for the paired PLRs. The One-way ANOVA and post-hoc Tukey HSD Test were used to compare the recommended PLR to the results and the significant differences (p<0.01). CONCLUSION: The recommended manufacturers' powder and liquid weights were KUH 0.150/0.05g; RSC 0.165/0.035; FIXH 0.18/0.05, respectively. KUH, FIXH and RSCH liquid had powder and liquid dispersions above the manufacturer's recommendations. FIXH had the most paired PLR observations within the ±10% range followed by KUH. Extreme powder and liquid combinations could occur in the clinical scenario and these combinations were considered.

In vitro analysis of the marginal adaptation and discrepancy of stainless steel crowns.

Aim: The purpose of the study was to assess the marginal adaptation and discrepancy of SSC's. Differences in adaptation and discrepancy between the four surfaces (mesial, lingual, distal, and buccal) were evaluated. Methods: The placement of stainless steel crowns were completed on a phantom head in accordance with the clinical technique. The ideal tooth preparation was made and this 'master tooth' duplicated to achieve a sample size of 15. The stainless steel crowns were placed, trimmed, and cemented as per the clinical technique. The cemented stainless crowns were analyzed under 100× stereomicroscope magnification. The marginal adaptation and discrepancy of each specimen was measured every 2 µm. Results: All the specimens showed marginal adaptation and discrepancy. The lingual margin had a significantly better adaptation (p < .0001) over the other surfaces. The buccal surface was the only surface that had an appropriate supra-CEJ level with a significance of p < .0001. Conclusion: The marginal discrepancies occur during the trimming procedure and assessment of the gingival approximation of the SSC margin. The inspection of stainless steel crown adaptation and discrepancy is an essential clinical step.