Browsing by Author "Osman, Yusuf I."
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Item Clinical evaluation of shade improvement after in-office vital bleaching(University of the Western Cape, 2010) Salem, Yousef; Osman, Yusuf I.Tooth discoloration has increased the demand by patients to pursue aesthetic treatment options. Bleaching is considered a conservative approach in performing an aesthetic treatment for discolored teeth; however colour rebound and post-operative sensitivity are among the adverse effects associated with vital bleaching. In-office bleaching systems employ the use of high hydrogen peroxide concentrations. The effects of in-office bleaching agents on the degree of colour change and the gender differences in relation to bleaching outcomes are questionable. Post-operative sensitivity can be considered a bleaching side effect and the number of patients that experience it is unknown.Aim: The aim of this study was to assess the outcome of an in-office vital bleaching technique. Objectives: The objectives of this study were to evaluate the degree of colour change after vital tooth bleaching using a 35% hydrogen peroxide gel (Yotuel® Special, Biocosmetics Laboratories, Spain), using a spectrophotometer (CM-2600d Konica, Minolta) to measure the colour change at each intervention during the bleaching process, to assess the post-operative sensitivity during the first week of the intervention, to evaluate the patients' perception of the colour change and to compare it to the colour change (ΔE) expressed in numeric values and to investigate whether gender differences exist in relation to the outcome of the bleaching procedure. Materials and Methods: The maxillary anterior teeth of 22 patients comprising of 11 males and 11 females were bleached with a 35% hydrogen peroxide gel (Yotuel® Special, Biocosmetics Laboratories, Spain). Pre-treatment readings of the two maxillary central incisors using a spectrophotometer (CM-2600d Konica, Minolta) were obtained. Subsequent readings were obtained after scaling and polishing, before bleaching (which was used as a baseline reading), immediately after bleaching, one week and one month post-operatively. Patients were requested to complete a form regarding post-operative tooth sensitivity and their colour perception toward the bleaching treatment. Results: The quantitative effect of the bleaching material on tooth colour showed an increase in L* values and a decrease in a* and b* values, the changes were significant (p values ≤ 0.05) except for the mean value of b* one month after bleaching which was only significant between five and ten percent.The mean values of colour change measured as ΔE between baseline and after bleaching was found to be 3.4 which did not exceed the visible colour change perceptible clinically at a difference of 3.7 units according to the literature. However nine patients exceeded the visible clinical colour change immediately after bleaching. There was no gender difference in the ΔE values in the entire bleaching process. Tooth sensitivity is considered a bleaching side effect and in this study sensitivity was traced until the fifth day after bleaching. The mean value of patients' tooth sensitivity was found to be 1.73 in the first day on a 4 point visual analog scale. The mean value of patients' colour perception was found to be 2.14 immediately after bleaching on a 3 point visual analog scale. Spearman correlation tests showed a positive relationship between ΔE values immediately and one week after bleaching and a weak relationship one week and one month after bleaching. There was significant consistency in the patients‟ colour perception data immediately and one week after the bleaching process and a weak relationship between ΔE values and patients' colour perception one month after bleaching. Conclusion: Yotuel® Special, Biocosmetics Laboratories, (Spain) an in-office bleaching material consisting of 35% hydrogen peroxide was able to bleach patients' teeth with a perceptible colour change however the chalky white teeth desired were not obtained for all the patients. Tooth sensitivity was a temporary side effect.Item A comparative study to evaluate patient satisfaction with conventional dentures and implant retained overdentures(University of the Western Cape, 2006) Al-Makki, Amjad; Osman, Yusuf I.; Wilson, V.J; Dept. of Restorative Dentistry; Faculty of DentistryThe edentulous jaw is a common feature in elderly patients that had lost their teeth during life due to local reasons such as poor oral hygiene and dental caries as well as periodontal disease. Hence these patients are the victims of biological phenomenona that lead to difficulties in different aspects of patient comfort with dentures. Clinicians are always concerned to minimize these difficulties and increase patient comfort through manufacturing a proper prosthesis to substitute for the loss of the natural teeth as well as the surrounding structures for optimum satisfaction and improved quality of life of the patient. The aim of this study was to evaluate patient satisfaction regarding function and aesthetics with conventional mandibular dentures and implant retained mandibular overdentures in denture wearers.Item Comparison of occlusal rest seat preparations to cast metal rests(University of the Western Cape, 2007) Cassim, Shabir; Osman, Yusuf I.; Wilson, Vivienne; Faculty of DentistryA well designed metal-based removable partial denture (MBRPD) is a cost-effective and a conservative method of rehabilitating a partially edentulous mouth. The MBRPD demands that the abbutment tooth provides support and/or retention while the abutment tooth, in turn, expects the MBRPD to transmit the forces axially and to be passive when fully seated. For vertical forces to be transmitted axially, occlusal rest seats have to be prepared on the abutment teeth to receive a cast metal rest of the MBRPD. The objective of this study was to compare occlusal rest seat preparations for metal-based removable partial dentures (MBPRD) prepared by dental students at the UWC Oral Health centres, to the corresponding cast metal rests and to determine action taken in response to discovered discrepancies between the rest seat preparation depth and the cast metal occlusal rset thickness.Item Disinfection procedures: effects on the dimensional accuracy of Gypsum casts(University of the Western Cape, 2007) Salih, Mayson; Wilson, V.J.; Osman, Yusuf I.; Dept. of Prosthodontics; Faculty of DentistryThe aim of the study was to assess the dimensional accuracy of Gypsum models following chemical disinfection of the impressions and to compare it with the accuracy of gypsum models exposed to microwave irradiation disinfection. Results indicated that the dimensional accuracy of the gypsum models disinfected in a microwave oven did not differ significantly from models in the control group. Except for models produced from SS white (SS White group, England) impressions where models irradiated in microwave exhibit significant improvement in the dimensional accuracy when compared with control group.Item The effect of storage time on dimensional accuracy of elastomeric impression materials(University of the Western Cape, 2008) Osio, Mary A.; Osman, Yusuf I.; Faculty of DentistrySeveral factors play a role in stability of impressions made from elastomeric impression materials. These include; polymerization shrinkage, loss of by-products during condensation, thermal contraction from oral temperature to room temperature, imbibition when exposed to water, disinfectant or high humidity and incomplete recovery from deformation due to viscoelastic behavior. An ideal impression material should be dimensionally stable over time to allow for pour at the convenience of the operator. Several studies evaluated the dimensional accuracy of elastomeric impression materials based on various factors including effects of repeat pour, temperature, humidity, disinfectants, impression techniques, and filler loading amongst others. Most of the previous studies did not use the standardized method described by the ADA specification for elastomeric impression materials.Item The effect of thermal-cycling on the bond strength of a two step and single-step dentin bonding agent(University of the Western Cape, 2010) Omer, Amir Isam; Osman, Yusuf I.; Faculty of DentistryThe aim and objective of this study was to determine the bond strength of a twostep and a single-step dentin bonding agent and to determine the effect of repeated thermal-cycling from 50C and 550C on the bond strength values of these dentin bonding agents.Item The efficacy of rotary and manual instruments in root canal debridement(2009) Madlabane, Duduzile; Osman, Yusuf I.It has been shown that the use of both manual and rotary instruments result in the formation of a smear layer and debris during root canal treatment. The amount that is formed depends on the type of instrumentation used as well as the force applied. The purposes of this study were to use the scanning electron microscope to compare the cleanliness of the root canal walls following rotary and manual debridement methods, to assess the transportation of the apical part of the root canal orifice when using different instrumentation techniques. Endodontic treatment was performed on extracted maxillary central incisors following extirpation and debridement using the Protaper® nickel titanium files and K-files. The teeth were randomly divided into three groups. Endodontic therapy performed simulated the clinical procedures, in which the teeth were extirpated using a barbed broach to remove the necrotic pulp. Pre-operative periapical radiographs were used to determine the working length. Root canals were debrided using the two filing methods, with copious irrigation using Sodium hypochlorite solution in a disposable syringe with a 27 gauge needle. A follow up radiograph with a master apical file in position was used to verify complete debridement in the apical third of the anal. The teeth were then sectioned vertically using a diamond bur to create an initial groove and then split apart using a flat plastic instrument to separate the sections and to avoid contamination of the sections. These sectioned portions were then studied under a scanning electron microscope. The mear layer as well as the amount of debris was evaluated. The assessment of residual debris and smear layer formed, were assigned numbers and tabulated. All three areas of the root canal were compared against each other. The sectioned apical third of the root canal was also studied for the presence or absence of apical transportation. From the present study, it was found that both the nickel-titanium rotary files and stainless steel hand files produced some smear layer and there was some residual debris left in uninstrumented areas of the root canal. However, it was shown that there was more smear layer formation when using nickel-titanium rotary files compared to that formed using hand files. When assessed for the presence of apical transportation, it was found that both types of instrumentation resulted in some degree of transportation, however, with rotary files, the canals remained largely centralized with transportation clearly visible in hand instrumented canals.Item The in vitro effect of a tooth bleaching agent on coffee and wine stained teeth(University of the Western Cape, 2008) Malyi, Emil C.; Osman, Yusuf I.; Grobler, Sias; Dept. of Restorative Dentistry; Faculty of ScienceSummary: Aim: The aim of this laboratory study is to assess the efficacy of a tooth bleaching agent by evaluating the degree of color change with the use of a spectrophotometer and not by the usual subjective, visual methods. Methodology: Twenty specimens of human teeth will be collected, polished and divided into two groups. A baseline color measurement by the CIE L* a* b* with a spectrophotometer against a white background will be taken before one group is immersed in coffee and the other in red wine for two weeks. Bleaching of the specimens will be done according to manufacturer’s instructions for two weeks. Color readings will be taken before bleaching, weekly during bleaching and 1 and 2 weeks after the bleaching treatment. Color change (ΔE) will be calculated mathematically as Δ E = [ (Δ L*)2 + (Δ a*)2 + (Δ b*)2 ]1/2. An observation of whether the baseline color reading will be regained by the bleaching process will be made. Results: Data collected will be recorded on an Excel spreadsheet. Advice from a qualified statistician will be sought to analyze the data. Results will be discussed in comparison with the existing literature on this subject.Item An in vitro study of composite repair(2007) Mohammed, Hesham; Osman, Yusuf I.The aim of this study is to investigate the repair bond strength of composite resin following micromechanical and chemical means of retention in improving the repair of composite resin specimens.Item An in vitro study of microleakage and surface microhardness of nanocomposite restorative materials(University of the Western Cape, 2005) Majeed, Abdul; Osman, Yusuf I.; Dept. of Restorative Dentistry; Faculty of DentistryThe demand for posterior aesthetic restorations has dramatically increased in recent years. Several new materials have been developed with improved aesthetic, adhesive and mechanical properties. However, microleakage elimination, especially if the margins are on dentine or cementum, and attainment of optimum mechanical properties for posterior use, are still questionable. The aim of this study was to investigate microleakage and surface microhardness of a nanofilled, a nanohybrid and an ormocer based nano-ceramic composite restorative material.Item An in vitro study of post-restorative bleaching: effect on microleakage(University of the Western Cape, 2010) Manni, Hassan; Osman, Yusuf I.; Faculty of DentistryAim and Objectives: To assess the effect of bleaching on the marginal integrity of Class V composite resin restorations. To determine the effect of a 6% hydrogen peroxide over the counter and a 38% hydrogen peroxide in-office vital bleaching treatment products on the microleakage of Class V composite restorations.Item An in-vitro study assessing the color stability of different provisional crown and bridge restorative materials(2006) Barbara, Ndagire; Osman, Yusuf I.; Grobler, S.The aim of this study was to investigate the color stability of two provisional restorative materials used in crown and bridge cases upon exposure to different tea staining solutions and to evaluate the effectiveness of a polishing technique in removing the tea stains from the stained provisional restorative materials.Item An in-vitro study assessing the effect of smear layer on root canal microleakage(2008) Elnour, Mutasim Hassan; Osman, Yusuf I.The aim of this study was to compare the sealing ability of AH Plus sealer to the canal wall in the presence and absence of the smear layer.Item Influence of a bleaching agent on stained direct composite resins(University of the Western Cape, 2008) Wanjau, Caroline; Osman, Yusuf I.; Dept. of Restorative Dentistry; Faculty of DentistryDespite the phenomenal strides in research of dental resin composites regarding their physical and mechanical properties, discolouration, either intrinsic or extrinsic still remains a major drawback and is one of the main reasons for the replacement of these restorations. Toothbrushing and polishing procedures have been attempted to eliminate extrinsic staining without optimal results. Vital tooth bleaching has over 90% success rates in whitening discoloured teeth and this may be an alternative treatment modality for discoloured composite resins. Aim: The aim of this study was to determine whether tooth bleaching agents alter the colour of stained direct composite resins. Material and Method: 60 disc shaped specimens (9 x 2mm) of Filtek Supreme XT were prepared. They were randomly divided into 3 groups (n = 20) and exposed to either one of two experimental staining agents, tea or red wine, or artificial saliva (control) continuously over a 7-day period. They were all then bleached with Opalescence Xtra Boost, a chemically activated in-office whitening agent for 3, weekly sessions of a half hour each, broken into 2, fifteen minute cycles. Colour determinations were made using a reflectance spectrophotometer, from baseline, after each day of staining, after the bleaching treatments and after a 1 week rehydration period. The CIE Lab colour space was used and colour changes were monitored using ΔE, that was calculated during intervals between the experimental episodes using L, a and b values. A ΔE ≥ 3.3 represented colour changes that were deemed clinically noticeable. Data analysis was carried out using Microsoft excel and a non-parametric test (Wilcoxon Signed Sum Rank Test) with a significance level set at ≤ 0.05 for colour differences that are statistically significant. Results: Both staining solutions discoloured the composite resin samples, but red wine produced greater colour changes than tea. After bleaching, the specimens in the tea group reverted to baseline colour with a ΔE ≤ 3.3 but those in the red wine group did not revert to baseline values with a ΔE ≥ 3.3. Conclusion: Filtek Supreme XT, a nanocomposite, is susceptible to discolouration by chromogenic beverages. Red wine produced deeper staining than tea. Opalescence Xtra Boost was effective in removing tea stains but not red wine stains.Item Oral health and nutritional status of the children under five years, Queen Elizabeth II Hospital, Maseru, Lesotho(University of the Western Cape, 2006) Linjewile-Marealle, Navoneiwa; Strydom, C; Osman, Yusuf I.; Faculty of DentistryThe aim of this study was to compare the oral health status between well and malnourished children under five years old attending Mother and Child Health clinic in Queen Elizabeth II Hospital in Maseru, Lesotho.Item Prevalence of signs and symptoms of temporomandibular joint dysfunction in subjects with different occlusions using the Helkimo index(University of the Western Cape, 2005) Kalanzi, Dunstan; Osman, Yusuf I.; Shaikh, A; Dept. of Restorative Dentistry; Faculty of DentistryThe controversy surrounding the role of malocclusion and orthodontic treatment in temporomandibular joint (TMJ) dysfunction led to this study. The purpose of this study was to establish the prevalence and compare the status of signs and symptoms of TMJ dysfunction in four groups of adolescents and young adults. The groups consisted of 14 persons with normal occlusions, 23 with untreated malocclusions, 20 with malocclusions currently undergoing treatment, and 18 with treated malocclusions. The Helkimo index was used to collect the TMJ dysfunction data. The results showed that the untreated malocclusion group had the most number of persons with signs and symptoms of dysfunction, but the differences between the groups in the distribution of persons according to the anamnestic and clinical dysfunction indices were not statistically significant. There were also no statistically significant differences in the distribution of signs and symptoms between boys and girls. According to anamnesis, the most frequently reported symptoms were joint sounds and headaches or neckaches occurring more than twice a week. Amongst the clinical signs and symptoms, the most commonly occurring were joint sounds on auscultation and muscle tenderness on palpation. In light of the small study sample and the absence of any substantial differences between the four groups, the role of malocclusion and orthodontic treatment in the aetiology of TMJ dysfunction remains obscure.Item The retentive strength of bonded amalgam restorations(University of the Western Cape, 2005) Banna, Trinadha Rao; Osman, Yusuf I.; Dept. of Restorative Dentistry; Faculty of DentistryAmalgam bonding agents have been shown to enhance retention of amalgam restorations by mechanical means. However, recent studies showed that the use o glass ionomer cements and resin cements as lining and bonding materials to amalgam restorations will increase the retentive strength of the amalgam restorations, hence reducing the micro leakage and secondary caries. The purpose of this study was to compare the relative retentive strength of conventional amalgam restorations and bonded amalgam restorations using resin adhesive, glass ionomer cements and resin cements.Item The retentive strength of bonded amalgam restorations(2005) Banna, Rao T.; Osman, Yusuf I.The purpose of this in vitro study is to compare the relative retentive strength of conventional amalgam restorations and bonded amalgam restorations using resin adhesive, glass ionomer cements and resin cements.Item Surface hardness of different shades and types of resin composite cured with a high power led light curing unit(University of the Western Cape, 2006) Lodhi, Tariq Abbas; Strydom, C.; Osman, Yusuf I.; Dept. of Restorative Dentistry; Faculty of DentistryLight-emitting diode (LED) curing lights were introduced to the dental market promising a higher curing efficiency than halogen-based lights. The earlier generation curing lights, however, proved not to be as effective as halogen lights. As a result 3M ESPE introduced a new high-powered LED curing light, the Elipar FreeLight 2, that delivers a greater irradiance. and threfore greater energy density than its precursor. Due to these changes, the light's manufacturer claims that the FreeLight 2 can cure resin composites at half of their recommended curing time. The aim of this study was to compare the effectiveness of cure when a FreeLight 2 was used to sure composite samples at 100% and at 50% of the recommended curing time.Item The taper of clinical crown preparations done by dental students and dentists in two African countries: a comparative analysis(University of the Western Cape, 2004) Enechi, Theophilus Chukwuemeka; Osman, Yusuf I.; Dept. of Restorative Dentistry; Faculty of DentistryCrowns have been used since the 5th century AD to improve both the form and function of teeth in the mouth. A great proportion of the total expenditure on dental care is spent on the provision and replacement of crowns and bridges and the number is increasing every year. A full coverage crown is a restoration placed over a single prepared tooth or it acts as an abutment in a bridge for the restoration of a missing tooth or teeth. Crowns are considered successful only when they meet both the aesthetic and functional requirements of the patient. For these to be met, certain principles for the preparation of the abutment tooth must be adhered to; such principles include features that are incorporated in the tooth preparation that enable it to withstand the forces of dislodgement that the tooth is exposed to both at rest and function. These features are described as the retention and resistance form of the preparation and the important aspect of these is taper. The taper of a tooth preparation is inversely proportional to the retention provided by the preparation. Volumes have been written on the difficulties encountered in making crowns with an adequate taper. Training, experience and operating conditions are among the many determinants of taper obtained by clinicians. Taper values of 2º to 5º were recommended initially for successful crown restorations but over time it was realized that these values were difficult to achieve under clinical conditions without creating undercuts in the preparation. Besides it was shown that even higher taper values might provide adequate retention for crowns. In addition, extra-retentive features such as axial grooves and boxes have been shown to improve retention of crowns. Many of the new luting cements also have adhesive properties that contribute to better retention of crowns and bridges. Various studies have established the prevalent taper obtained by dental students, general practice dentists, residents and prosthodontists while some of these studies have compared the prevalent taper among the different categories of clinicians. None of the studies so far reported has shown the prevalent taper in this environment; all without exception have investigated conditions in Europe, North America and Asia. Aim: This study therefore investigated the prevalent taper obtained routinely under clinical conditions by dental students, general dental practitioners and prosthodontists in two African countries and compared them with the recommended range of 10º to 22º.Method: 432 dies of teeth prepared by students, general practice dentists, resident and practicing prosthodontists were collected and analysed for taper using the double silicone technique. This involved making silicone replicas of the dies, sectioning these at various points and using photographs of the sections to measure their taper. Comparisons of the tapers obtained were carried out between the students, general practitioners and prosthodontists as well as between taper obtained on the different tooth types. Results: Taper ranging from 2º to 100º was obtained on the various tooth types. A mean mesio-distal (MD) and bucco-lingual (BL) taper of 22.5º (SD 11.2) and 26.2º (SD 11.1) respectively and a mean overall taper of 24.3º (SD 9.2) were obtained. Prosthodontists obtained the lowest taper (MD = 20.5º (SD 10.6)), BL = 24. 5º (SD 10.1) and a mean overall taper of 22.5º (SD 8.4). Students were second with a mean MD taper of 23.8º (SD 10.1), BL taper of 26.1º (SD 10.9) and a mean overall taper of 25.0º (SD 8.4). The general practice dentists obtained a mean MD and BL taper of 24.5º (SD 12.4) and 29.1º (SD 12.1) respectively and a mean overall taper of 26.8º (SD 10.6). The lowest taper was seen on premolars while the highest was on molars. Conclusion and recommendation: Most of the preparations analysed had a taper outside the recommended range of 10º to 22º. However, these tapers were similar to those found in other studies. Routinely incorporating extra-retentive features into crown preparation designs will improve success of crown restorations and adhesive cements should be used whenever conditions that allow for adequate retention are not met. The importance of taper should be emphasized more in dental schools and tooth preparation support systems should be used for teaching wherever possible. The need for regular refresher courses for practicing dentists and prosthodontists cannot be over-emphasized.