Browsing by Author "Moodley, Desi"

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    Comparison of colour components between maxillary central incisors - an in vivo study
    (South African Dental Association, 2015) Moodley, Desi; Grobler, Sias Renier; Osman, Yusuf Ismail; Kotze, T.J.v.W.
    Objectives: The purpose of this study was to determine the relationship of colour in the CIE L a b scale between the maxillary central incisors. Methods: The colour of the maxillary central incisors of 83 patients was measured (in vivo) using a spectrophotometer. Three measurements (6 mm diameter) at the centre of the crown of each of the maxillary central incisors were performed. Results: The total colour difference (?E ab) showed wide variability with the average ?E ab = 1.79. The Wilcoxon Signed Rank Test showed statistically significant differences (p < 0.05) between maxillary right (11) and left central incisors (21) in both the L and b colour components. In the a scale no significant difference was noted. Conclusion: Small colour differences exist between the maxillary central incisors in the same individual when evaluated with a spectrophotometer. Clinical significance: As there is often a difference between the colours of the two central incisors in the same patient, the colour of both the central incisors should be taken into consideration when shade matching anterior teeth.
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    Cytotoxicity testing of various dentine bonding agents using human pulp fibroblast cell lines and a 3T3 mouse fibroblast cell line.
    (University of the Western Cape, 2007) Moodley, Desi; Grobler, Sias
    Introduction: Biocompatibility of all kinds of dental materials is of paramount importance In order to prevent/limit irritation or degeneration of the surrounding tissues where it is applied. Some researchers suggested that dentine bonding agents may be used for pulpal protection, while pulpal inflammation and inhibition of pulpal repair following the use of dentine bonding agents were also reported. Objectives: The first part of this study compared the cytotoxicity of human pulp cell lines to a mouse 3T3 cell line to cytotoxic challenges from dentine bonding agents. The second part of the study compared the cytotoxicity of recent dentine bonding agents namely, Scotchbond 1, Prime & Bond NTand Xeno III through artificial membranes as well as thin dentine discs (after its reaction with apatite) and Clearfil Protect Bond (CPB)as such, as well as the primer part of CPBand the bond part of CPB separately. Methods and Materials: Near confluent human pulp cells and 3T3 cells were exposed to culture medium (DMEM)extractions from the various polymerized agents mentioned above and the cell viability (survival rate) was measured using the standard MTTassay and related to the non-exposed controls. Results: Two human pulp cells lines were more sensitive to 3T3 cell lines while the other human cell line was less sensitive to the 3T3 cell line. All bonding agents as such were found to be cytotoxic towards the 3T3 cells with Xeno III (25%survival rate) and CPB (35%)the most cytotoxic. Of the two parts from CPB the bond part was the least toxic (91% survival rate), but the primer part (containing the anti-bacterial pyridinium molecule) was very toxic (30% survival rate). ScotchBond 1 (59% survival rate) and Prime & Bond NT (62% survival rate) were not statistically different (Kruskal-Wallis Test, p>0.05). However,the survival rate of Xeno III (25% through membrane as well as dentine discs) and Clearfil Protect Bond (35%) were significantly lower than that of the other two bonding agents, with Xeno III significantly the most toxic (p<0.05 ) Conclusion: In general, all 4 dentine bonding agents were cytotoxic of which Xeno III was the most toxic even after its reaction with apatite (through dentine discs). The most toxic part of CPB was found to be the primer part containing the pyridinium linked molecule. If human pulp fibroblasts are used for cytotoxicity testing of dentine bonding agents many cell lines must be used.
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    An in-vitro evaluation of repair protocols applied to composite resin
    (University of the Western Cape, 2016) Irari, Ken W.; Moodley, Desi; Patel, Naren
    The shift towards minimally invasive dentistry has meant that dental practitioners are now undertaking procedures that are conservative and preserve as much of the existing tooth structure as possible. Repairing composite is a more conservative way of managing damaged restorations when compared to their replacement. A number of different protocols for repairing composite restorations exist but there is little information as to which is the most effective method. Aim: The aim of this study was to evaluate the effect the following treatment procedures have on the shear bond strength of repaired composite: i. Five different repair protocols, ii. Two different types of repair composite materials and iii. Aging in artificial saliva prior to repairing. Materials and methods: Two hundred and forty composite cylinders of 5mm diameter and 5mm height made from Filtek Supreme XTE (3M ESPE, St. Paul, MN, USA) were prepared with the aid of a silicon matrix. They were then divided into two groups: a hundred and twenty of these cylinders were aged in a solution of artificial saliva for 28 days and the remaining samples were left unchanged with no aging. All the aged and non-aged composite cylinders were then randomly allocated to six groups of twenty each corresponding to the repair protocol applied. The first group from both of the aged and non-aged samples was treated by roughening the top surface with a diamond bur followed by an application of Scotchbond 1XT (3M ESPE, St. Paul, MN, USA). The second group received a surface roughening with a diamond bur,etching with 35% phosphoric acid and application of Scotchbond 1XT. The third group received an application of Scotchbond Universal (3M ESPE, St. Paul, MN, USA) and the fourth one had a single application of Tetric N-Bond Universal (Ivoclar Vivadent AG, Schaan, Liechtenstein) on its top surface. The fifth group was treated by blasting with COJET Sand (3M ESPE, St. Paul, MN, USA) particles together with an application of Scotchbond Universal. The final group was used as the control where no surface treatment was done. After the surface treatments, each of the composite samples was repaired by the addition of fresh composite in the shape of cylinders measuring 3mm in diameter and 4mm in height. This was done with the aid of a silicon matrix. Within each treatment sub-group (n=20), 10 cylinders were repaired using either Filtek Supreme XTE or Tetric N-Ceram. All two hundred and forty repaired samples were then subjected to shear bond strength testing on a Universal testing machine. Data analysis: The results of the shear bond strength tests expressed in megapascals (MPa) were recorded and analysed for the effect of three different factors under consideration. The effectiveness of the repair protocols, type of composite and aging in artificial saliva were compared using the analysis of variance. Differences within the groups were identified using a post hoc analysis. Results: The mean highest repair shear bond strength was observed when COJET Sand in conjunction with Scotchbond Universal was used to repair the aged composite blocks. There were no significant differences in the shear bond strength observed when either Filtek Supreme XTE or Tetric N-Ceram was used as the repair composites. Aging in artificial saliva led to a mean reduction of 18.08% in the repair bond strength across the six treatment groups. Conclusions: The application of a surface treatment and intermediate adhesive is crucial in improving bond strength in the composite repair interface. Repair with Filtek Supreme XTE and Tetric N-Ceram was equally effective. Aging in artificial saliva produced significantly reduced bond strength.
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    An in-vitro evaluation of the efficacy of oral devices to remove dental biofilm from three prosthodontic materials
    (University of the Western Cape, 2019) Ahmed, Omnia Abdelmoneim Khidir; Moodley, Desi
    Introduction: The evolution of Dentistry witnessed an increase in fixed prostheses as opposed to removable ones. Zirconia (ZrO2) and Lithium disilicate (LDS) are becoming the material of choice in implant or tooth retained prostheses. Polyetheretherketone (PEEK) is a recent alternative as it is lighter and causes less wear of opposing retained teeth. Biofilm formation is a permanent daily struggle for patients as it can be found in nearly all surfaces exposed to the natural environment. Therefore, the interest in a new device capable of removing or reducing oral biofilm from fixed prostheses is increasing. Aquaflosser (AQ) and Waterpik (WP) are examples of these oral irrigating devices that were introduced to the dental market recently. They can be effective in removing dental biofilm from different surfaces. Purpose of study: The purpose of this study is to evaluate biofilm formation on three fixed dental substructures and to evaluate the efficacy of two oral irrigating devices on biofilm removal from these three substructures.
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    Influence of variations in ceramic thickness and bonding substrate on the fracture resistance of lithium disilicate restorations
    (University of the Western Cape, 2017) van Lierop, Jean; Moodley, Desi
    Restorative dentistry aims to replace lost or damaged tooth structure with durable and life-like alternatives. To accommodate the inherent limitations and weakness of the restorative materials, preparation techniques often require the sacrifice of healthy tooth structure to create enough restorative space. This can lead to weakening of the remaining tooth structure, with subsequent damage or catastrophic failure. When using indirect restoratives, the development of adhesive luting agents (adhesive cements) and stronger allporcelain restorations (lithium disilicate) has contributed to the development of “minimally invasive” preparation techniques and concepts such as cavity design optimization (CDO) and bio-substitution. With these techniques, resin materials are combined with ceramic restoratives in an attempt to not only produce strong restorations, but also increase the longevity of the remaining tooth. The clinician needs to therefore find the ideal preparation design that combine such materials to produces a clinically performing restoration while increasing the strength and longevity of the underlying tooth.
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    Insights into a comparison of three different cements on the push-out bond strength of a glass-fibre post
    (SADA, 2017) Grobler, Sias Renier; Patel, Naren; Fortuin, A.; Moodley, Desi
    One of the main causes of failure of fibre posts is debonding of the post in the prepared post space. The adhesive properties of total etch adhesive cements were assessed by comparing the performance of cements using self-etching adhesive resins, to verify which system provided the best retentive capabilities with a double tapered post system. Extracted maxillary central incisors were endodontically treated and randomly divided into three groups: the Calibra (Dentsply), RelyX Ultimate (3M ESPE) and Panavia F2.0 (Kuraray) groups. RelyX Ultimate produced significantly the highest de-bond stress values (p<0.05) in the overall performance, as well as in the coronal, middle and apical sections of the tooth. Thus RelyX Ultimate with self-etching adhesive reliably can be used for post cementation with a double tapered post system in endodontically treated anterior teeth.
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    Local anaesthetics in dentistry - Part 2: Choice of local anaesthetic agent
    (SADA, 2017) Moodley, Desi
    Currently, in general dentistry the most commonly used local anaesthetic agents are 2% lignocaine (Xylotox, Adcock Ingram; Xylesthesin, 3M) with 1:80000 adrenaline content, 3% mepivicaine (Carbocaine) without a vasoconstrictor and 4% articaine (Ubistesin 3M) with either 1:100000 or 1:200000 adrenaline concentration.
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    Local anaesthetics in dentistry - Part 3: Vasoconstrictors in local anaesthetics
    (SADA, 2017) Moodley, Desi
    Vasoconstrictors like adrenaline in local anaesthetics are associated with more drug interactions than any other drug in Dentistry1 with an incidence of adverse reactions ranging from 2.5%-11%.2 Therefore, understanding the physiological and pharmacological effects, interactions with other drugs, and dosages are important in day to day dental practice.
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    Local anaesthetics in dentistry: A series
    (SADA, 2017) Moodley, Desi
    Failure in local anaesthesia in dentistry is not uncommon with failure rates ranging approximately between 15% and 30%, especially for the inferior alveolar nerve block (IANB). In fact of all the nerve blocks which may be administered in the human body the IANB has the highest failure rate (Malamed, 2012). Therefore, the aim of this series of articles is the discuss some of the causes of failure in local anaesthesia and make recommendations so as to minimize the experience. Current trends like computer controlled local anaesthetic delivery, reversal of soft tissue anaesthesia for patient comfort and “needle free” anaesthesia will be discussed.
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    Management of necrotic pulp of immature permanent incisor tooth: A regenerative endodontic treatment protocol: case report
    (South African Dental Association, 2017) Moodley, Desi; Patel, Naren; Peck, Craig; Moodley, Tashia
    It is possible that a paradigm shift may be in the offing in the approach to treatment of immature teeth with necrotic pulp, away from traditional apexification procedures and to a biologically-based endodontic protocol intended to produce regeneration, based on the deliberate introduction of bleeding into the canal space to provide a scaffold and allow the ingress of stem cells. METHODS: A patient presented with a maxillary right central incisor tooth with an open apex and periapical radiolucency. The tooth was irrigated with sodium hypochlorite and then dressed with tri-antibiotic paste consisting of ciprofloxacin, metronidazole and amoxicillin. At a subsequent visit a blood clot was produced in the canal by irritating periapical tissues and the canal then sealed with mineral trioxide aggregate and glass ionomer cement. RESULTS: The patient was pain free, the draining sinus was resolved in two weeks, root maturation continued and apical closure occurred after two months. The tooth became responsive to cold pulp vitality testing. CONCLUSIONS: Continued root growth invoked by regenerative endodontics may reduce the risks of fracture and premature tooth loss otherwise associated with traditional CaOH2 apexification procedures. Randomised, prospective clinical trials and long term studies are required before the technique becomes standard practice.
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    Micro-hardness and depth of cure of dental bulk-fill composites
    (University of the Western Cape, 2015) Abughufa, Hajer; Moodley, Desi; Patel, Naren
    Resin composite is one of the most commonly used materials in restorative dentistry. However, it has undergone continuous developments like changes in the fillers and initiators. One such improvement is the new bulk-fill composites which are materials intended for bulk placement up to 4mm. However, an optimum polymerization to the full depth of the restoration i.e. complete depth of cure is of utmost importance in order to obtain proper mechanical and physical properties of resin composites. Aim: The aim of this study was to measure the surface hardness of the top and bottom surfaces of the composites and to determine the depth of cure of bulk-fill composites using two different types of light curing units. Material and methods: A total of 160 specimens were used in this study: four bulk-fill composite were used of which two were conventional viscosity bulk-fill composites namely, Tetric N Ceram (Ivoclar Vivadent) and SureFil bulk-fill composite (Densply Caulk) and two were low viscosity flowable bulk-fill composites namely, SDR flowable (Densply Caulk) and Filtek bulk-fill flowable restorative (3M ESPE). Two different curing light were used namely, LED (Elipar Freelight, 3M ESPE) at 1500mW/cm2 and a Quartz Tungsten Halogen (QTH) curing unit (Megalux CS, Megadenta, Germany) at 600 mW/cm2. To evaluate micro-hardness, Vickers hardness at top and bottom of each sample was measured immediately after light curing and after 24 hours post curing using a Zwick micro-hardness machine load 300g/15 seconds. The mean hardness values obtained from the top and the bottom surface of each material were used to compare the micro-hardness of the various materials. The mean values obtained from the bottom surface were compared to the respective values of the top surface of each material (bottom/top ratio) and used to calculate the depth of cure. Results: The micro-hardness test showed a significant difference between the four materials (ANOVA, p<0.05) immediately after curing and after 24 hours post curing. The material with the greatest micro-hardness was SureFil followed by Tetric N Ceram, Filtek bulk-fill flowable and SDR flowable respectively. The material with the greatest depth of cure was Filtek bulk-fill flowable followed by SDR flowable, Tetric N Ceram and SureFil. When the curing lights were compared the Light Emitting Diode Curing Unit (LED) obtained significantly better depth of cure compared to Quartz Tungsten Halogen Light Curing Units. The LED curing light showed greater micro-hardness values than the QTH curing light except for Tetric N Ceram where the QTH curing showed more hardness values than the LED curing light. For all materials, the surface hardness and depth of cure values increased when tested 24hrs after light curing. Conclusion: There was a difference in the micro-hardness values between the four materials where the conventional viscosity materials showed greater surface hardness values than the low viscosity materials but the depth of cure compared to the bulk-fill flowable LED curing lights showed higher hardness values than QTH curing light except for Tetric N Ceram. Depth of cure ratios were found to be lower than 0.80 for all composite types, however the flowable bulk-fill materials showed higher depth of cure than the conventional viscosity bulk-fills. In general LED curing light produced better hardness and depth of cure values than QTH curing light. The low micro-hardness values for the bulk-fill flowable composites and the inadequate polymerization raises a concern regarding placing these materials in bulk. In such cases, the flowable bulk-fills should be protected with a conventional composite "covering or capping" especially in posterior teeth and in deeper cavities. Furthermore, bulk-fill composites should be used in layering incremental technique to ensure sufficient depth of cure.
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    A shear bond strength, microleakage and laser microscopic study of two dental compomers.
    (University of the Western Cape, 1999) Moodley, Desi; Grobler, Sias
    Purpose: To evaluate and compare the in-vitro shear bond strength and micro leakage of two compomers with their adhesive systems and to examine the dentine-restorative interface under confocal scanning laser microscopy (CSLM). Matoiats and Methods: For shear bond strength (SBS) testing thirty non-carious human molars were used of which fifteen molars were restored with Dyract AP using Non-Rinse Conditioner (NRC) and Prime&Bond NT (PBNT) and fifteen were restored with F2000 and Scotchbond Multi-Purpose Plus (SBMP). For the microleakage evaluation cavity preparations were made on the facial surfaces of thirty non-carious premolars. These were then restored with the respective compomer system. The specimens were thermocycled, sectioned and examined for dye penetration. The dentine-restorative interface was examined through a confocal scanning laser microscope. The primers of the bonding agents were labelled with rhodamine B and the adhesive resins were labelled with fluorescein and examined under CSLM in fluorescent mode. Results: The mean SBS for PBNT and SBMP were 12.8 and 18.1 MPa, respectively. The microleakage scores showed Dyract with PBNT leaked on the dentine side in 13 of the 15 specimens examined. On the enamel side 2 of the 15 specimens showed microleakage. With F2000 and SBMP no micro leakage was observed on either enamel or dentine sides. The CSLM images show clear resin tag and hybrid layer formation for both the materials examined, although SBMP showed deeper penetration into the dentine with longer resin tags. The length of the resin tags and thickness of the hybrid layer for PBNT was found to be approximately 10 um and 2 um respectively. SBMP showed resin tags measuring about 100 um while the hybrid layer measured about 5 um. Conclusion: This study demonstrates that the acid-etch technique ofSBMP with F2000 produces higher bond strength and no micro leakage when compared to the self-etching/self-priming "non-rinse technique" of NRC with PBNT and Dyract.
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    Towards bioactive dental restorative materials with chitosan and nanodiamonds: evaluation and application
    (SciDoc Publishers, 2015) Mulder, Riaan; Grobler, Sias Renier; Moodley, Desi; Perchyonok, Tamara
    BACKGROUND/PURPOSES: Recently various articles showed beneficial effects of the addition of different the beneficial effect (bond strength and longevity) of the addition of different bioactive compounds towards dental materials. compounds towards dental materials. Therefore, the aim of this work was to evaluate the effect of the addition of bioactive materials and combination thereof (chitosan/nanodiamond or cyclodextrin/nanodiamond) to a dental composite. MATERIALS AND METHODS: The flowable composite Premise by Kerr was used as the standard control dental material. Premisewas also modified to contain: 10% nanodiamonds/Premise, 10% chitosan/nanodiamonds/Premise, 10% cyclodextrin/ nanodiamonds/Premise and 10% cyclodextrin/Premise and tested for their dentin bond strength, volumetric shrinkage, Vickers hardness and cytotoxicity. RESULTS AND CONCLUSION: Beneficial effects of the addition of different bioactive compounds towards dental materials were proved. A higher shear bond strength (p < 5%) was found after 3 months of Premise treated with nanodiamonds, chitosan, cyclodextrin (CD) and combinations thereof than the control Premise. The sequence for the Vickers hardness was: CD (32.5) < nano (34.8) < CD Nano (38.8) < Premise (39) < Chitosan Nano (42.2). Chitosan was found to increase the mouse 3T3 fibroblast cell survival rate (113%), while nanodiamonds (92%) and the combination of chitosan + nanodiamonds (93%) showed little cytotoxicity. The shrinkage was lower for all the additions than for Premise alone. Nanodiamonds and the combination chitosan + nanodiamonds showed little cytotoxicity towards mouse 3T3 fibroblast cells.
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    Use of antibacterial nanoparticles in Endodontics
    (South African Dental Association (SADA), 2017) Ibrahim, A. I. O.; Moodley, Desi; Petrik, Leslie; Patel, Naren
    Several root canal irrigants and medicaments are available to combat endodontic pathogens. However, evidence of complete elimination of these pathogens by the use of these solutions is not recorded in the literature. The possible development of resistant bacterial species is one of the problems related to the efficacy of the currently available irrigants and medicaments. In addition, the complex anatomy of the root canal system allows endodontic pathogens to be hidden in areas inaccessible to the action of the irrigating preparations. This is further enhanced by the protective layer that is formed by the remnants of pulp tissue, dentin powder and dead cells which inhibit the antibacterial activity of the root canal irrigants and medicaments. Antimicrobial nanoparticles show promising effect against resistant pathogens in pharmaceutical science as a result of their unique physio-chemical properties. Unlike traditionally used antimicrobial agents, these nanoparticles destroy bacterial cells through multiple mechanisms. The concept of using nanoparticles in endodontics as a new treatment modality was developed recently and their antibacterial efficacy against endodontic pathogens was evaluated by several researchers in many in vitro studies. This article reviews some of the currently available literature on laboratory studies that evaluated the efficacy of nanoparticles against endodontic pathogens.
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    Water sorption and solubility of resin filled composites
    (University of the Western Cape, 2015) Omar, Hana Ali Alharari; Moodley, Desi; Patel, Naren
    Resin filled dental composite materials has been introduced into dental practice since mid-1960s as an aesthetic restorative material for anterior teeth (Bowen, 1962 cited in Peutzfeldt, 1997). Since then, they have undergone several developments in order to enhance the longevity and performance of these materials. Resin filled dental composites consist of three main components namely, organic resin matrix which consists of a monomer, an initiator system and a stabilizer system, inorganic filler such as quartz, silica, etc. and coupling agent such as organo-silane coupling agent that chemically bonds the inorganic fillers to the organic resin matrix (Phillips, 1973). The properties and the performance of the resin filled dental composites are basically dependent upon the components of the materials. Some properties are related to the resin matrix, whereas others are related to the inorganic fillers and coupling agent. Furthermore, properties such as polymerization shrinkage and water sorption are dependent on both the inorganic fillers and the organic resin matrix (Asmussen, 1975; Hashinger and Fairhust, 1984; Munksgaard et al., 1987). Aim and objectives: The aim and the objectives of this study was to compare the water sorption and solubility of four bulk-fill dental resin composite materials namely, two conventional viscosity bulk-fill (Surefil bulk fill composite and Tetric N Ceram Bulk Fill) and two low viscosity bulk-fill flowable dental composite materials (Filtek Bulk Fill flowable restorative and Surefil SDR Flow). Materials and methods: Four types of bulk-fill composite restorative materials (2 bulk-fill conventional viscosity (Surefil bulk fill composite and Tetric N Ceram Bulk Fill) and 2 bulk-fill flowable low viscosity (Filtek Bulk Fill flowable restorative and Surefil SDR Flow) were used to analyse the water sorption and solubility for each resin composite type. Thirty specimens for each type of material were prepared, giving the total number of specimens to be 120 (n=120). To standardize this study Vita shade A2 was used for all the material types. All specimens were prepared in a Teflon mould with internal diameter of 15±1mm and thickness of 1±0.1mm in accordance with ISO 4049. The light curing unit used for all specimens was Elipar™ S10, (3M ESPE, Germany) at an output of 1200 mW/cm2 and used according to the manufacturer’s instructions. Prior to curing, the intensity of the light was checked using Cure Rite visible curing light meter (Caulk, USA) to ensure light output consistency between specimens and was found to be 1200 mW/cm2 . All the specimens were first removed from the Teflon mould as prepared and described previously and placed in an oven at 37 ºC until their weights were constant and these weights were recorded as m1 by using an analytic balance (OHAUS, TS400D, USA). Ten specimens of each type of resin filled composite were then immersed individually in glass containers filled with 10 ml distilled water and placed in the oven at 37±1 ºC for 24 hours, 7 days, 14 days respectively. The specimens were removed; surface water was blotted with tissue paper until free from visible moisture and weighed using the analytic balance (OHAUS, TS400D, USA). The resultant weights were recorded as m2. The specimens were then placed in a desiccator containing silica gel (Associated Chemical Enterprises, ZA) and freshly dried for two hours in an oven at 58 ºC and then weighted to obtain m3. According to Oysaed and Ruyter formula (Oysaed and Ruyter, 1986), the water sorption and solubility was calculated using the following equation: i.Water sorption (SP) = m2 -m3 / v., ii.Water solubility (SI) = m1 -m3 / v - where v is the volume of the specimen. For monomer leakage high performance liquid chromatography (HPLC) was used to identify monomers. The water that contained stored specimens was transferred to a refrigerator immediately after the specimens were removed until HPLC analysis was carried out to determine the amount of monomers that leached out of the cured composite specimens. Results: A significant difference between the materials (p<0.05, ANOVA Analysis of Variance) showed that Surefil SDR Flow composite had the lowest overall mean water sorption values (10.191) over the three time intervals (24 hrs, 7 days and 14 days) which was significantly smaller than the other means, followed by Filtek Bulk Fill flowable restorative composite (11.135) and Tetric N Ceram Bulk Fill composite (16.419). The highest water sorption mean value was recorded for Surefil bulk fill composite (21.515). The overall means of water solubility for the two bulk-fill flowables i.e. Filtek Bulk Fill flowable restorative and Surefil SDR Flow were smaller than bulk-fill conventional viscosity Surefil bulk fill and Tetric N Ceram Bulk Fill. However, all the test materials displayed no statistically significant increase in water solubility over the time period (p > 0.05 two way ANOVA test). The amounts of eluted monomers from bulk-fill conventional viscosity materials (Surefil bulk fill and Tetric N Ceram Bulk Fill) were higher than bulk-fill flowable materials (Surefil SDR Flow and Filtek Bulk Fill flowable restorative). Of all the monomers tested UDMA eluted more than Bis-GMA and TEGDMA. Overall UDMA monomer eluted the most, followed by Bis-GMA and the TEGDMA. Conclusion: Within the limitation of this study, the results of this study did not support the null hypothesis that there is no significant difference in the water sorption. The bulk-fill low viscosity flowables showed lower water sorption than the conventional viscosity bulk-fills. Surefil SDR Flow was significantly lower than the other materials followed by Filtek Bulk Fill flowable restorative and Tetric N-Ceram Bulk Fill and the highest overall means were recorded for Surefil bulk fill. For water solubility the overall means for the flowables of Filtek and SDR were smaller than Surefil and Tetric N-Ceram. For monomer elution three monomers were detected of which UDMA monomer eluted the most, followed by Bis-GMA and the TEGDMA. With regards to the elution of monomers, it was found that 3 monomers named UDMA eluted more than Bis-GMA and TEGDMA.
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    The whitening effect of four different commercial denture cleansers on stained acrylic resin
    (South African Dental Journal, 2016) Maart, Ronel Deidre; Kruijsse, H.; Osman, Yusuf Ismail; Moodley, Desi; Patel, Naren; Grobler, Sias Renier
    Denture hygiene and denture cleansers are very important for their antimicrobial effect and also in removing stain from the dentures. The purpose of this study was to determine the effectiveness of Steradent, Corega, Dentalmate and Fitty Dent in improving the colour of stained, polished-and unpolished, acrylic specimens and to determine which colour component should be the visual impression factor. Samples of stained acrylic specimens were severally exposed once to one or other of the denture cleansers. The colour components (L*, a* and b*) of the specimens were measured with a spectrophotometer before and after exposure to one of the four products. In general there was only a slight non-significant improvement (p>0.05) in the yellowness (a*) and redness (b*) of the acrylic samples as a result of a single treatment with any of the four stain removal products. However, the L* value was mainly negatively influenced. The differences (ΔE*ab; ΔL*; Δa* and Δb*) between before and after treatment for any one of the four products were also not statistically significant on a 5% level (Kruskal Wallis nonparametric test). Conclusion: A small improvement of the yellowness and redness could be seen even after a single treatment. This was found for all four commercially available denture cleansers on polished and on non-polished specimens. From the relative magnitudes of L*, a* and b* which contribute to the overall colour value (ΔE*ab) it was statistically confirmed that the brightness/lightness component (L*) should be the visual impression factor.