Saudi Cultural Missions Theses & Dissertations
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Item Restricted The effect of surface treatment on the adhesive strength of chairside hard liners to dental polymers used for the conventional, additive, and subtractive fabrication of complete dentures(The Ohio State University, 2022) Aldosari, Abdullah Mohammed A; Azer, Shereen S.; Schricker, Scott R.; Lee, Damian J.Objectives: The aim of this in vitro study was to evaluate the tensile bond strength of two hard denture relining materials on denture bases fabricated from conventional, subtractive, and additive polymers. In addition, this study assessed the effect of a polymer to resin primer on the tensile bond strength of hard denture liners to different denture bases. Methods: A total of 120 hard relined denture base samples were fabricated, 40 per denture base group (Lucitone 199, Ivo Base CAD, and NextDent Denture 3D+). For each denture base group 20 samples were hard relined with one of two chair side hard denture liner (GC Reline, MucoHard). Among the hard reline groups, 10 of each group was primed with a composite to PMMA primer (Visio.link). All samples underwent thermocycling. The adhesive strength was evaluated through tensile testing. The surface contact angle was measured on each denture group sample to evaluate the wettability of the material. The data was analyzed using Inverse-variance weighted linear regression. Results: In this study overall the denture bases relined with MucoHard denture liner had significantly higherbond strength than the GC reline groups (P<0.016). The highest tensile bond strength was achieved by combining MucoHard denture liner and primed 3D printed denture base, followed by the non-primed conventional denture base, and non-primed milled denture base to MucoHard denture liner. The surface primer used in this study (Visio.Link primer, Bredent UK Ltd. Chesterfield, UK.) had a significant effect on the tensile bond strength of all tested groups (P<0.0003). However, the primer only positively influenced the bond strength of the 3D printed denture base to MucoHard denture liner, while the other groups were inversely affected. Conclusion: There was no significant difference in the tensile bond strength of chairside denture liners to denture bases fabricated using additive, subtractive, and conventional methods (P>0.05). The highest bond strength was achieved with the combination of MucoHard denture liner and primed 3D printed denture bases. MucoHard denture liner has overall significantly higher tensile bond strength in comparison to GC reline. (P<0.016) The primer only positively influenced the bond strength of MucoHard to 3D printed denture bases. The primer significantly alters the wettability of the denture bases.53 0Item Restricted Comparison of an experimental single application two-step 25600 ppm Ammonium Fluoride / 34100 - 48600 ppm Nano-Calcium Fluoride solution vs. a one-step 7700 ppm Ammonium Fluoride varnish for Preventing Enamel Loss from Erosion and Attrition in vitro(King’s College London, 2024) Almejrad, Lamya; Austin, Rupert; Bartlett, DavidIntroduction: The potential for high-fluoride treatments to prevent progression of erosion and attrition is not fully understood. This thesis investigated the effect of an experimental two-step ammonium fluoride/nano-calcium fluoride formulation (25600 ppm NH4F plus 34100 - 48600 ppm CaF2) versus a single-application one-step 7700 ppm ammonium fluoride (NH4F) varnish on step height loss (μm) of polished and natural human enamel undergoing erosion and attrition in vitro. Material and methods: Three restorative dental materials and human enamel (Occlusal vs. Buccal) samples were used to validate the attrition simulation method. Samples were subjected to attritional wear using leucite-reinforced CAD/CAM ceramic antagonists in an electrodynamic wear simulator (200 cycles, 80 N load, 0.7 mm horizontal slide). Following validation, polished and natural (unpolished) enamel samples were pre-treated with either deionized water (DIW negative control), NH4F varnish (positive control) or a two-step NH4F/CaF2 solution. After surface wiping, samples were subjected to erosion (0.3% citric acid solution immersion, pH 3.8, for 5, 10, 15, 20 and 60 minutes) and attrition (200 strokes). Enamel wear was measured using non-contact laser profilometry (NCLP). Enamel surface and sub-surface mechanical testing was conducted using micro- and nanoindentation. Enamel surface and sub-surface qualitative examination was conducted using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Results: The attrition method revealed that the glass ionomer material experienced the most wear, measuring 177.8 μm (±16.9). This was significantly more than the fine particle composite, which showed 22.2 μm (±1.3) of wear, and the micro-filled composite, which had the least wear at 13.6 μm (±1.02) (P < 0.001). Enamel samples from buccal vs. occlusal sources experienced non-significantly different step height enamel wear (P<0.05). The attrition wear generation was consistent with co-efficient of variation <10%. Polished enamel samples treated with surface fluoride treatments showed significantly reduced step height enamel loss vs. control (p<0.001): Mean (SD) enamel loss for DIW treatment was 1.97 μm (±0.14) after erosion and 36.55 μm (±1.79) after erosion/attrition. NH4F treatment reduced loss to 0.58 μm (±0.08) after erosion and 32.71 μm (±2.63) after erosion/attrition (p<0.001). NH4F/CaF2 treatment further reduced loss to 0.41 μm (±0.06) after erosion and 24.08 μm (±3.15) after erosion/attrition (p<0.001). This was supported by the microhardness data: fluoride-treated enamel experienced reduced hardness changes following both erosion and erosion/attrition vs. non-fluoride treated enamel (p<0.001). For natural enamel, the experimental NH4F/CaF2 solution significantly reduced enamel loss after all erosion durations (5, 20, 60 minutes) and after 200 strokes of attrition. After 5 minutes of erosion, enamel loss compared to DIW was significantly reduced (p<0.001). Mean (SD) enamel loss in the NH4F/CaF2 treated group was reduced to 0.21 μm (±0.13) after erosion and 9.82 μm (±1.46) after erosion/attrition in comparison with DIW treated groups which was 0.79 μm (±0.32) after erosion and 15.58 μm (±2.49) after erosion/attrition. The surface and sub-surface SEM and EDS data supported these findings. Conclusion: The two-step ammonium fluoride solution (NH4F/CaF2) reduced step height enamel loss and hardness changes occurring in polished and natural enamel during simulated erosion and attrition in vitro.16 0Item Restricted Evaluation of the Fit and Accuracy of Conventional and CAD/CAM Removable Partial Denture Frameworks Using Different Manufacturing Techniques and Materials(2023) Ghazal, Iraqi; Mathew, Kattadiyil; Montry, Suprono; Roberto, SavignanoStatement of problem. The use of computer-aided design and computer aided manufacturing (CAD/CAM) technology continues to increase in removable partial denture fabrication. To date, few studies have evaluated the fit and accuracy of conventional and CAD/CAM removable partial dentures (RPDs) using different manufacturing techniques and materials. Purpose. The purpose of this in vitro study was to compare the fit and accuracy of conventional versus CAD/CAM fabricated RPD frameworks using cast cobalt-chromium (Co-Cr) alloy, SLM cobalt-chromium (Co-Cr) alloy, milled aryl ketone polymer (AKP), and milled modified polyetheretherketone (PEEK). Materials and Methods. A total of 4 groups of 10 samples in each group were included in this study, for a total of 40 samples (n=40). Fit and accuracy of conventional and CAD/CAM fabricated RPD frameworks using different materials including cobalt-chromium (Co-Cr) alloy, aryl ketone polymer (AKP), and modified polyetheretherketone (PEEK) were evaluated using digital superimposition. Analysis of variance (Kruskall-Wallis) was conducted with a significance level of α=0.05 to determine whether the differences between each processing methods were statistically significant. Scheffe post-hoc test was used to compare the overall accuracy and fit among the different groups. Results. Color mapping revealed statistically significant differences between the conventionally cast Co-Cr framework group versus the SLM Co-Cr framework, milled AKP framework, and 2 milled PEEK framework groups with less overall gap with the conventional cast Co-Cr framework group. The most significant gap (0.63mm ± 0.08mm) was observed with the Anterior strap of the major connector. Conclusion. Within the limitation of the present study, the cast cobalt-chromium (Co-Cr) RPD framework revealed better fit when compared with SLM cobalt-chromium (Co-Cr), milled aryl ketone polymer (AKP), and milled modified polyetheretherketone (PEEK) frameworks. Milled Aryl Ketone Polymer and milled modified polyetheretherketone RPD frameworks revealed better fit when compared with SLM cobalt-chromium (Co-Cr) RPD framework. Retentive arms and the rest showed better fit when compared with anterior and the posterior strap of the major connector, the reciprocal arm, and the guiding plates among all tested groups. Anterior strap of the major connector had the greatest discrepancy among all tested groups. Clinical Implications. The overall fit and accuracy of both conventional and CAD/CAM removable partial dentures (RPDs) using different manufacturing techniques and materials were clinically acceptable.20 0Item Restricted Effect of Finishing and Polishing Techniques on the Fit Accuracy and Dimensions of Conventional and CAD-CAM Removable Partial Denture Frameworks(2023-07-13) Altoman, Majed; Kattadiyil, MathewRapid advancements in computer-aided design and computer-aided manufacturing (CAD- CAM) in removable dental prosthodontics have offered new modalities for fabrication of removable partial denture frameworks. The standard tessellation language (STL) files of the scans are used to digitally design the removable partial denture (RPD) framework, which are then printed in cobalt-chromium (Co-Cr) alloy and finished and polished according to manufacturers’ recommendations. There are few studies compare the fit accuracy of the cast DPD framework versus the CAD CAM RPD frameworks which found that CAD-RP frameworks exhibited the highest discrepancies, using different methods of evaluation. Good fit between the denture base and the supporting tissue, the intimate contacts between the teeth and framework components improve support, stability and retention and are critical to the satisfactory outcome for the RPD patient. Currently, no study has evaluated the fit accuracy of 3D printed removable partial dentures (RPD) after finishing and polishing techniques based on the manufacturer’s protocol. Purpose: The purpose of this study was to: 1) Compare the effects of finishing and polishing techniques on the overall fit accuracy and dimension of conventional versus CAD-CAM fabricated RPD frameworks. 2) Evaluate the loss of metal from various components of the RPD framework after finishing and polishing. Material and methods: A maxillary arch 3D printed model with a Kennedy class III modification I situation was fabricated as a master cast. The master model was scanned and used to compare the fit and accuracy of the RPD frameworks. The master cast were made and divided into 4 groups based on fabrication method: group I, lost-wax technique (conventional technique), group II, CAD-printing, group III, CAD-printing from stone cast, and group IV, lost-wax technique from resin-printed model. RPD frameworks were fabricated in cobalt-chromium alloy. The finishing and polishing techniques of the RPD frameworks using different methods were performed based on manufacturers’ recommendation. All RPD frameworks were scanned, and accuracy of fitting and metal thickness loss of various components of the RPD framework were evaluated. All RPD frameworks were evaluated the surface roughness based on SEM analysis. Results: All RPD frameworks were evaluated before and after finishing and polishing techniques based on manufacturers’ recommendation. Color mapping revealed state statistically significant between cast RPD framework versus 3D printed frameworks major connectors, reciprocal and retentive arms among the groups after finishing and polishing techniques based on manufacture’s recommendation (P < 0.05). There was statistically significant difference between the conventionally cast framework groups (LWT versus LWTR) compared to the 3D-printed framework groups (CAD-RP versus CAD-RPS) (P < 0.001). The biggest gap (0.33 mm ± 0.20 mm) was observed with the guide plates with the printed frameworks (groups II and III). The overall metal loss after using different finishing and polishing techniques revealed statistically significant differences in metal loss between the conventional polishing and finishing technique of cast RPD frameworks (P < 0.001) compared to the D-Lyte polishing and finishing technique of 3D printed frameworks particularly in the occlusal rest and the junction with the proximal plate. The conventional finishing and polishing technique showed more surface roughness than D- lyte finishing and polishing technique based on scanning electron microscope (SEM) analysis. Conclusion: Within the limitations of the present study, although both conventional cast RPD and 3D printed frameworks were found to be clinically acceptable, the conventionally processed RPD groups revealed better overall fit and accuracy after finishing and polishing. The conventional cast RPD frameworks showed more metal loss than 3D printed RPD frameworks after finishing and polishing technique and more surface roughness based on SEM analysis.32 0Item Restricted Physico-mechanical characterisation of polymeric CAD/CAM materials for aesthetic and prosthetic applications(2023-06-28) Babaier, Rua; Silikas, Nick; Watts, DavidPolymer-based CAD/CAM blocks have been suggested as a viable metal-free alternative to meet the needs of aesthetics, biomimetics, and minimally invasive dentistry. Therefore, this research characterised various optical, surface, and mechanical aspects of new reinforced polymeric CAD/CAM materials, subdivided based on their clinical applications into aesthetic (Part I) and prosthetic (Part II) sections. The blocks investigated for Part I were three resin composites, one polymer-infiltrated ceramic network (PICN), and one feldspathic ceramic; for Part II, three high-performance polymer (HPP) composites, which included two fibre-reinforced composites (TRINIA, TR, and CarboCAD 3D Dream Frame, CC), and one ceramic-filled polyetherether ketone (DentoKeep, PK). For Part I, firstly, thickness-dependent apparent radiopacity and material composition were investigated for five aesthetic blocks versus that of direct resin-based substrates. PICN appeared relatively radiolucent even at 2.5 mm thickness, posing challenges for its identification from tooth structure and other substrate materials, such as luting cements. Secondly, material- and thickness-dependent translucency, blue-light transmittance, and its consequences on polymerising two IvocerinTM-containing luting cements (light-cured, LC, and dual-cured, DC) were investigated after 1 h of irradiation through four CAD/CAM substrates. PICN showed the least favourable optical features, resulting in significantly lower hardness of the underlying DC cements. Overall, LC cement exhibited greater early hardness compared to DC, irrespective of the substrate thickness. For Part II, the surface and mechanical stability of HPP composites were examined after 1 and 7 days of ageing in three food-simulating solvents (water, 70% ethanol/water, and MEK). Significant material variations in terms of microstructural composition have reflected on the properties investigated, such as roughness, hardness, flexural strength, and fracture toughness. In comparison to TR and CC, PK demonstrated relative stability after accelerated aging. CC and TR were sufficiently strong at sections as thin as 1 mm. However, their increased deterioration in FSLs requires full protection with a veneer material. This research concludes that although initial results were promising, more material enhancement and a review of the currently proposed clinical applications are necessary.11 0Item Restricted Survival of Endocrowns Restoring Extensively Damaged Endodontically Treated Premolars(2023) Quqandi, Rufaida; Joshi, NiranjanMethods: Twenty-seven extracted premolars were assigned randomly into three different groups; Control Group1 (G1): Prefabricated glass fiber posts with 2-mm ferrule, Group2 (G2): Prefabricated glass fiber posts with no ferrule, and Group3 (G3): Endocrown with no ferrule. All groups received endodontic treatment followed by Lithium Disilicate restoration that was adhesively luted using 10-Methacryloyloxydecyl dihydrogen phosphate (10-MDP) containing resin cement. Each group underwent thermocycling of 10,000 cycles at 5oC and 55oC for 30 seconds in each bath. Specimens were subjected to a cyclic fatigue test for 840,000 cycles while being immersed in distilled water. Specimens that survived the mechanical fatigue testing were loaded-to-failure and failure mode was analyzed. Results: All samples survived the mechanical cyclic fatigue testing without any evident failure. The one-way ANOVA showed statistical significance between the fracture resistance of the groups (p = < 0.05). Tukey’s pairwise comparison test revealed a statistically significant difference between the fracture resistance of the control group (G1) in comparison to (G2) and (G3) (p < 0.05) and no statistical significance between (G2) and (G3) (P < 0.862). All groups showed the highest rate of favorable failure modes. Conclusion: Endocrowns displayed reliability as an alternative restorative treatment option for patients with severely compromised endodontically treated premolars as they are a fast, reliable, minimally invasive, and cost-effective treatment option compared to conventional treatment of post, core, and crown.17 0