Browsing by Author "Patel, Naren"

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    An in-vitro evaluation of the physical properties of a new bulk-fill composite
    (University of the Western Cape, 2017) Eltayeb, Aziz; Patel, Naren
    Dental composite is a synthetic resin that is used as a tooth coloured restorative material in dentistry. It became the material of choice in the dental field due to its superiority in strength and aesthetics (Garcia et al., 2006). Composite resin has favourable physical properties such as high wear resistance and shade stability. The main disadvantages are as follows: polymerization shrinkage which leads to marginal leakage; discoloration of the filling; postoperative sensitivity; and recurrent caries (Garcia et al., 2006). In order to decrease the application time of incremental layering techniques in conventional resin composite restorations, bulk-fill composites were introduced to the dental market with modifications in physical and mechanical properties. BulkFill composite can be applied in a single one-step increment layer of 4 - 5mm, saving considerable time during the clinical procedure when compared to the conventional composite layering technique of 2 mm (Leprince et al., 2014).
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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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    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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    The interaction between physical sign, and chronic pain depression and nonspecific physical symptoms, in patients with temporomandibular
    (University of the Western Cape, 1997) Patel, Naren; Wilding, R.J.C.
    There are both physical and emotional components which are associated with the chronic pain of TMD patients. One of the difficuhies in making an accurate assessment of each component, is the lack of objective criteria for quantitative measurement of the emotional component. This need, lead to the development of Research Diagnostic Criteria (RDC) by Dworkin and LeResche (1992). The aim of this study was to use RDC criteria to record the prevalence, and associations between Axis I (physical) and AXIS TI(emotional) factors in a sample of 100 patients attending a TMD Clinic. Patients were examined using the RDC guidelines and the diagnosis classified as either, myogenic, disc displacement or arthritis. Patients completed a self-administered personal history questiotmaire which analyzed emotional factors including, chronic graded pain, depression and nonspecific physical symptoms such as headaches, faintness and lower back pain.
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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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    Management of necrotic pulp of immature permanent incisor tooth: A regenerative endodontic treatment protocol: case report
    (SADA, 2017) Moodley, Desigar S.; Peck, Craig; Moodley, Tashia; Patel, Naren
    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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    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.