Department of Prosthodontics
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Browsing by Author "Geerts, Greta"
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Item A comparative study between thermoplastic and conventional removable partial denture designs(University of the Western Cape, 2019) Farao, Warren Emile; Geerts, GretaThree dental laboratories in the Cape Town Metropole that were known to fabricate “flexible” or NMCDs for dental practices were identified and were invited to participate in the study. Their participation consisted of emailing photographs of completed metal-frame, acrylic and flexible RPDs and their casts prior to sending them to the practices for delivery to patients. Specimens were collected until a total of 20 metal-frame, 20 acrylic resin and 20 flexible RPDs were received. A design was drawn for each submitted RPD. For each RPD, an “ideal” design was drawn, using the image of the cast. This was done by two observers, who are experienced members of staff in the Department of Restorative Dentistry (Prosthetics), independently. The designs from both observers were later compared for similarity. Where differences existed in the designs, these were resolved by means of discussion until agreement was reached. Each ideal design served as the control for each clinical design.The number of rests, their configuration, the type of support, number of clasps, the presence of indirect retention, cross-arch stabilization, the number of teeth whose periodontal tissues were covered by design components for each design among the different denture type groups, and corresponding control designs were identified and reported. The ratios of teeth replaced/teeth covered per denture type groups and per classification, and corresponding control designs were compared.Item Complete denture occlusion: intra and inter observer analysis(University of Western Cape, 2014) Mpungose, Sandile Khayalethu Derrick; Geerts, GretaAim: The aim of this study was to investigate the accuracy, intra- and inter-observer reliability of identifying occlusal markings made by articulating paper on complete dentures intra-orally. Methods: A series of photographs of 14 tissue borne complete dentures with occlusal markings was obtained. Articulating paper was used intra-orally at the delivery visit to make the occlusal markings. The denture sets were divided into two groups. Group 1 comprised pictures of the 14 complete lower dentures on their own, and group 2 comprised pictures of the same 14 lower dentures together with their opposing upper denture. The two groups of images were loaded into a Microsoft PowerPoint presentation as well as Keynote. Two experienced observers analysed the complete dentures independently and noted the number and distribution of the markings that they felt required adjustment. They differed, but discussed these and reached consensus. These data served as the control. Three groups of observers (10 per group) were then asked to analyse the occlusal markings of the 2 groups of denture images twice, with a two-week interval between each assessment. Before each subsequent assessment, the images were randomised by means of computer-generated random number sequence. The mean number of markings was established for each group and compared with the control mean. Intra-rater reliability was established by comparing the difference of the means of sequential observations for each rater by establishing the z-value. Inter-rater reliability within each group was established by means of analysis of variance. Results: Considering all the data, in only 17 instances (of the possible 60), did observers’ mean scores not differ from the control mean scores with good intra-rater reliability. In all other 43 instances the observers’ mean scores differed from the control mean scores and/or displayed poor intra-rater reliability. Considerable variation in inter-rater reliability was also found within every group of observers. Conclusion: The results indicate that observers are generally unable to reliably identify occlusal markings warranting occlusal adjustment, made by articulating paper on a lower complete denture. Clinical significance: Articulating paper should not be used intra-orally when delivering removable complete dentures.Item The effects of diferent reinforcements on the fracture toughness of provisional restorative materials(University of the Western Cape, 2006) Overturf, Jan Hendrik; Geerts, Greta; Dept. of Prosthodontics; Faculty of DentistryOne of the most critical aspects of successful crown and bridgework is temporary restorations. Failure of temporary restoratins often affects the patient's confidence and mau result in unscheduled appointments for repair. This study compared the the fracture toughness of two materials commonly used to fabricate provisional restorations, namely Coldpac, a polymethyl methacrylate and Protemp 3 Garant, a bis-acryl composite. It also compard the fracture toughness of the two materials when reinforced with stainless steel wire, glass fibers and polythylene fibers.