Browsing by Author "Grobler, Sias"
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Item Bio-Active Nano-Diamond Designer Materials and Dentures: From Design to Application(Dentistry, 2015) Perchyonok, V. Tamara; Souza, John; Zhang, Shengmiao; Moodley, Desigar; Grobler, SiasObjective: The present study aims to design functional biomaterials and evaluate performance of nano-diamond: chitosan based bio-active containing PMMA (polymethyl methacrylate) materials towards application in treatment and prevention of denture stomatitis and associated conditions in denture wearers. Methods: The bio-active nano-diamond modified PMMA were prepared by dispersion of the corresponding component in glycerol and acetic acid with the addition of chitosan gelling agent. The release behaviors at physiological pH and also under acidic conditions and stability of the antioxidant-chitosan-nano-diamond were also evaluated. Mechanical performance such as tensile strength and compressive strength were measured as well bio-adhesive studies were investigated in order to assess the suitability of these designer materials. Results: The bio-active nano-diamond modified PMMA materials showed a high adhesive force and they only swelled slightly in the aqueous medium. Bioactive release suggested prolonged release of the therapeutic agent from the hydrogels. The hydrogels also had significant free radical defense capability. Conclusion: In this study we demonstrated that the newly prepared bio-active modified PMMA resins are suitable novel bio-active materials capable of comparable performance with the conventional PMMA materials with additional benefit of therapeutic bioactive release as well as potential antimicrobial properties to be demonstrated in vitro. Our findings might be thus a step forward towards the development of alternative non antibiotic based strategies targeting bacterial infections.Item Bond strength of metal orthodontic brackets to all ceramic crowns(University of the Western Cape, 2016) Ismail, Moosa; Shaikh, Amenah; Grobler, SiasAim: The aim of this study was to evaluate, in-vitro, the shear bond strength (SBS) and the resultant failure pattern after debonding of metal orthodontic brackets bonded with TransbondTM XT adhesive resin cement and RelyXTM Unicem 2 self-adhesive resin cement to pre-treated (35% ortho-phosphoric acid and silane coupling agent application) IPS eMax and porcelain veneered zirconia crowns. Material and methodology: A Typhodont maxillary lateral incisor was used and prepared in a conventional manner to receive a full ceramic crown. A CAD (computer aided design)/ CAM (computer aided manufacturing) machine was used to scan the prepared tooth and manufacture 40 IPS eMax crowns and 40 porcelain veneered zirconia crowns. Half the number of IPS eMax crown specimens (ie. 20) and half the number of porcelain veneered zirconia crown specimens (ie. 20) were thermocycled (ie. to mimic thermal changes which occur in the mouth), from 5 to 55o for 500 cycles as recommended by the International Organization for Standardization (ISO 6872, 2008). The remaining 20 IPS eMax crown specimens and 20 porcelain veneered zirconia crown specimens remained new and unexposed to thermal changes. The facial surfaces of all the thermocycled and non-thermocycled crown specimens were then etched. Etching of all the ceramic bonding surfaces was performed by the application of 35 per cent ortho-phosphoric acid liquid for 2 minutes, followed by a thin layer of a ceramic primer. A lateral incisor metal bracket with a bracket base area of 9mm2 (as confirmed by the manufacturer) was bonded to each of the etched and silane treated ceramic crown specimens and separated in the following manner: Group 1: (10 thermocycled, etched and silane treated IPS eMax and 10 thermocycled, etched and silane treated porcelain veneered zirconia crown specimens) RelyX™ Unicem 2 self-adhesive resin cement was used to bond the bracket to the ceramic crown specimens, Group 2: (10 thermocycled, etched and silane treated IPS eMax and 10 thermocycled, etched and silane treated porcelain veneered zirconia crown specimens) Transbond™ XT light cure adhesive primer was first applied onto the bonding surface of the crowns and then Transbond™ XT adhesive resin was used to bond the bracket to the ceramic crown specimens, Group 3: (10 non-thermocycled, etched and silane treated IPS eMax and 10 non-thermocycled, etched and silane treated porcelain veneered zirconia crown specimens) RelyX™ Unicem 2 self-adhesive resin cement was used to bond the bracket to the ceramic crown specimens, Group 4: (10 non-thermocycled, etched and silane treated IPS eMax and 10 non-thermocycled, etched and silane treated porcelain veneered zirconia crown specimens) Transbond™ XT light cure adhesive primer was first applied onto the bonding surface of the crowns and then Transbond™ XT adhesive resin cement was used to bond the bracket to the ceramic crown specimens. After bonding all samples were stored in distilled water for 24 hours before being submitted to the shear bond strength test. Debonding forces in Newtons (N) was determined by using a shear testing machine and converted into Mega Pascals (MPa). Results: The results after debonding were compared. The mean shear bond strength for RelyXTM Unicem 2 self-adhesive resin cement bonded to the all ceramic non-thermocycled crowns (Group 3) ranged from a low of 5.1 MPa (45.5 Newtons) when brackets were bonded to the IPS eMax crowns to a high of 5.8 MPa (51.9 Newtons) when brackets were bonded to the porcelain veneered zirconia crowns. The mean shear bond strength for Transbond XT adhesive resin cement bonded to the all ceramic non-thermocycled crowns (Group 4) ranged from a low of 6.4 MPa (57.3 Newtons) when brackets were bonded to the porcelain veneered zirconia crowns to a high of 8.1 MPa (72.7 Newtons) when brackets were bonded to the IPS eMax crowns. The side by side Box-and-Whisker plots of the shear bond strengths show wide and overlapping dispersions of the crown/adhesive resin combinations which consequently lessen the probability of significant differences between the crown/adhesive resin combinations in all 4 groups. According to the Kruskal-Wallis test (p < 0.05), and the Bonferroni Test the non-thermocycled crown/adhesive resin combinations do not differ significantly. Study of the mean ARI (Adhesive Remnant Index) values for the non-thermocycled crown/adhesive combinations shows that brackets bonded with Rely-XTM Unicem 2 to non-thermocycled porcelain veneered zirconia crowns failed entirely at the ceramic/adhesive interface and for all the other non-thermocycled ceramic/adhesive combinations most of the failures of the bond (70%) occurred at the bracket/adhesive interface, ie. cohesive fractures within the composite resin. No cohesive fractures of the porcelain crowns were noted. The results of the thermocycled groups (Group 1 and Group 2) show the TransbondTM XT/non-thermocycled IPS eMax crown combination yielded the highest overall mean shear bond strength of 8.1 MPa (72.7 Newtons) but dropped to a mean shear bond strength of 5.1 MPa (46.1 Newtons) (36.4% drop in shear bond strength) when the crowns were thermocycled prior to bonding. The TransbondTM XT/non-thermocycled porcelain veneerd zirconia crown combination yielded the second highest overall mean shear bond strength of 6.4 MPa (57.3 Newtons) and dropped to a mean shear bond strength of 5.1 MPa (45.8 Newtons) (19.3% drop in shear bond strength) when the crowns were thermocycled prior to bonding. The RelyXTM Unicem 2/non-thermocycled porcelain veneered zirconia crown combination yielded the third highest overall mean shear bond strength of 5.8 MPa (51.9 Newtons) but dropped significantly to a mean shear bond strength of 3.2 MPa (29.1 Newtons) (a significant 43.8% drop in shear bond strength) when the crowns were thermocycled prior to bonding. Lastly, the RelyXTM Unicem 2/non-thermocycled IPS eMax crown combination yielded the fourth highest mean shear bond strength of 5.1MPa (45.5 Newtons) but dropped to a mean shear bond strength of 4.9 MPa (44.5 Newtons) (a drop in shear bond strength of only 3%) when the crowns were thermocyled prior to bonding. Relaxing the significance level (p-value) somewhat demonstrates the negative influence of thermocycling on the shear bond strength of the crown/adhesive combinations. The non-thermocycled all ceramic crown/adhesive combinations showed mean ARI values of between 1.3 and 2.1 indicating cohesive fractures within the composite resin and efficient bonding of the adhesive material to the porcelain surface. However, all the thermocycled all ceramic crown/adhesive treatment combinations showed mean ARI values of between 0 and 0.8 indicating a bond failure between adhesive and porcelain and highlighting the negative influence of thermocycling on bond strength of both adhesive resin cements. Conclusion: Within the limitations of this study, it can be concluded that: 1.There was no significant difference in the shear bond strengths of metal orthodontic brackets bonded with RelyXTM Unicem 2 self-adhesive resin cement and metal orthodontic brackets bonded with TransbondTM XT adhesive resin cement to IPS eMax and porcelain-veneered zirconia crowns which were conditioned with 35 % phosphoric acid and a silane coupling agent. 2. Conditioning the porcelain surface with 35% phosphoric acid and a silane coupling agent (which is safer to use than Hydrofluoric acid) is sufficient for bonding metal orthodontic brackets to all ceramic crowns, and should make it simpler for clinicians to remove the remaining adhesive from the porcelain surface after debonding. 3. The negative influence of thermocycling prior to bonding can be seen on shear bond strength values. 4. Most of the failures of the bond occurred at the ceramic/adhesive interface and cohesive fractures within the composite resin. No cohesive fractures of the porcelain crowns were noted.Item Comparative bond strengths of stainless steel orthodontic brackets bonded with different bonding agents(University of the Western Cape, 2007) Hudson, Athol Peter Gilfillan.; Grobler, Sias; Harris, Angela; Faculty of DentistryThe aim of this project was to compare the shear bond strengths of three light cure orthodontic adhesive resins with three different stainless steel molar brackets.Item 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, SiasIntroduction: 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.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 A shear bond strength, microleakage and laser microscopic study of two dental compomers.(University of the Western Cape, 1999) Moodley, Desi; Grobler, SiasPurpose: 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.Item Temporomandibular Joint Dysfunctions and Bio-Materials: Design, Free Radical Defense and Mechanism In Vitro(EC Dental Science, 2015) Perchyonok, V Tamara; Souza, Tatiana; Moodley, Desigar; Basson, Nickolas; Zhang, Shengmiao; Grobler, SiasThe aim of this investigation is to evaluate the suitability and flexibility of the bio-active containing designer materials to act as an “in vitro” probe to gain insights into molecular origin of TMJ. The hydroxyapatite/chitosan containing hydrogels represent a reliable biocompatible scaffold and allowed to evaluate the defense “build in” free radical defense mechanism of the functionalized bio-scaffolds on the molecular level, compare the effectiveness of the designer materials with the earlier reported capabilities of N-acetyl cysteine and apply the newly developed materials for the evaluation of new therapeutic treatment modalities in the TMJ therapy in vitro. Materials and Methods: The hydrogels were prepared by dispersion of the corresponding component in glycerol and acetic acid with the addition of chitosan: hydroxyapatite as a molecular scaffold. The surface morphology (SEM), release behaviors (physiological pH and also in acidic conditions), stability of the antioxidant-chitosan were also evaluated. Structural investigations of the reactive surface of the hydrogel are reported. Bio-adhesive studies and mechanical properties of newly prepared materials were conducted to assess the suitability of these designer materials. Ability of the materials to release the phenolic components as potential therapeutic agents was assessed. Results: The sustained release of total phenolic component as a potential therapeutic agent confirms the added benefit of synergistic action of a functional therapeutic delivery when comparing the newly designed chitosan/HA-based hydrogel molecular scaffold. The hydrogel formulations have a uniform distribution of drug content. The bio-adhesive capacity, tensile strength, compressive strength as well as modulus of elasticity of the hydroxyapatite containing materials in the “in vitro” systems was tested and quantified. Conclusion: The added benefits of the chitosan hydroxyapatite treated hydrogels involved positive influence on the phenolic component release, sustainable bio-adhesion, tensile strength, compressive strength as well as modulus of elasticity of the hydroxyapatite containing materials in the “in vitro” systems was tested and demonstrated in vitro “build in” free radical defense mechanism.Item Towards Bio-active Restorative Materials with Copaiba Oil and Oblepicha Oil: In vitro(J Dent Oral Disord Ther, 2015) Perchyonok, V. Tamara; Moodley, Desigar; Grobler, Sias; Souza, Tatiana; Augusto de Souza, Joane; Zhang, ShengmiaoWe developed and evaluated chitosan - fucoidan bio-composites with additional bioactive components of oblepicha oil and copaiba oil for bioactive restorative material as intra-dental and wound healing applications such as bioadhesion to soft and hard tissue in vitro, dentin bond strength and free radical defense mechanism for the compounds in the oral environment.