UWCScholar :: Browsing by Author "Geerts, G"

Browsing by Author "Geerts, G"

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Analyzing Complete Denture Occlusal Contacts: Accuracy and Reliability
(Quintessence Publishing, 2016-02) Mpungose, SK; Geerts, G
The aim of this study was to investigate the accuracy and reliability of interpreting occlusal markings made by articulating paper on complete dentures intraorally. Clinical teachers at a training hospital interpreted occlusal markings intended for adjustment. Their scores were compared to a control score to determine accuracy. For reliability determination, the observations were repeated. Only between 20% and 30% of observations were found to be both accurate and reliable. Unless the procedure can be standardized, this technique shouldn't be considered appropriate prosthodontics protocol for balancing the occlusion of complete dentures.
Broad Spectrum Anti-Bacterial Activity and Non-Selective Toxicity of Gum Arabic Silver Nanoparticles
(MDPI, 2022-02-04) Fadaka, AO; Meyer, S; Ahmed, O; Geerts, G; Madiehe, MA; Meyer, M; Sibuyi, NRS
Silver nanoparticles (AgNPs) are the most commercialized nanomaterials and presumed to be biocompatible based on the biological effects of the bulk material. However, their physico-chemical properties differ significantly to the bulk materials and are associated with unique biological properties. The study investigated the antimicrobial and cytotoxicity effects of AgNPs synthesized using gum arabic (GA), sodium borohydride (NaBH4), and their combination as reducing agents. The AgNPs were characterized using ultraviolet-visible spectrophotometry (UV-Vis), dynamic light scattering (DLS), transmission electron microscopy (TEM), and Fourier-transform infrared spectroscopy (FT-IR). The anti-bacterial activity was assessed using agar well diffusion and microdilution assays, and the cytotoxicity effects on Caco-2, HT-29 and KMST-6 cells using MTT assay. The GA-synthesized AgNPs (GA-AgNPs) demonstrated higher bactericidal activity against all bacteria, and non-selective cytotoxicity towards normal and cancer cells. AgNPs reduced by NaBH4 (C-AgNPs) and the combination of GA and NaBH4 (GAC-AgNPs) had insignificant anti-bacterial activity and cytotoxicity at ≥50 µg/mL. The study showed that despite the notion that AgNPs are safe and biocompatible, their toxicity cannot be overruled and that their toxicity can be channeled by using biocompatible polymers, thereby providing a therapeutic window at concentrations that are least harmful to mammalian cells but toxic to bacteria.
A comparison of the accuracy of two methods used by pre-doctoral students to measure vertical dimension
(Elsevier, 2004-01) Geerts, G; Stuhlinger, ME; Nel, DG
Statement of problem. Measuring vertical dimension is a soft-tissue measurement. Therefore, inaccuracy may occur. Purpose. The purpose of this study is to compare the accuracy of the Willis gauge method with the caliper method. Material and methods. The Willis gauge measures the distance between the septum of the nose and the chin. The caliper method measures the distance between reference points on the tip of the nose and the chin. Twenty predoctoral students applied both methods 10 times in measuring the rest vertical dimension (RVD) and the occlusal vertical dimension (OVD) of a single edentulous patient. The measurements obtained from one experienced clinician were selected as controls for the interocclusal distances (IOD) for the Willis and the caliper methods, respectively. One-sided t tests and a 1-sided nonparametric test were used to determine significant differences between the 2 methods ( .05). Results. The variances in the RVD values for the Willis gauge method were higher than for the caliper method for most students. A Wilcoxon signed rank test showed that the accuracy of the OVD measurements for the caliper method was significantly better than for the Willis gauge method (P .001). This was not the case for the RVD measurements (P .073).The average IOD for the Willis method was significantly higher than the control IOD (P .026). The average IOD for the caliper method was not significantly larger than the control (P .1303). Conclusion. This study showed that the use of the caliper method by predoctoral students was a significantly more reliable method of measuring the OVD for the patient evaluated
A comparison of the bond strengths of microwave- and water bath-cured denture material.
(Elsevier, 1993-11) Geerts, G; Jooste, CH
A comparison was made of the shear bond strengths between microwave-polymerized and conventional water bath-cured polymethyl methacrylate (PMMA) bonded to denture teeth. Four groups of 15 specimens were prepared and shear bond strengths obtained by use of standardized laboratory testing methods. The results showed that microwave-cured PMMA demonstrated significantly (p 0.0001) higher bond strengths than conventional PMMA, and priming of the denture tooth surface with monomer liquid yielded significantly higher bond strengths than other surface treatment (p 0.0001).
Comparison of the clinical abrasion resistance of six commercially available denture teeth.
(Elsevier, 1997-01) Jooste, C; Geerts, G; Adams, L
Purpose: Clinical abrasion of denture teeth has certain implications when dentures are worn in excess of the average useful lifetime. The purpose of this study was to evaluate clinical denture tooth wear over a period of 3 years. Material and methods: The wear of six commercially available denture teeth (Premierdent, Acrotone, vitapan, Rx1, Duravite, and Ivoclar Orthosit) and a seventh combination of teeth was compared. Seventy patients with complete dentures were divided into seven groups of 10 each to form the study population. Results: There were no significant differences among the commercial denture teeth. Porcelain/Vitapan teeth exhibited the highest amount of abrasion. Significant wear was also measured between the Ivoclar Orthosit and Porcelain/Vitapan teeth.
Fracture resistance of endodontically treated premolars with fibre-reinforced composite restorations.
(Dennis Barber Ltd, 2011-03) Geerts, G; Pitout, E; Visser, H
This study investigated the fracture resistance and failure mode of endodontically treated premolars restored with a glass fibre-reinforced composite resin. Endodontically treated maxillary premolars were divided in 4 groups: group O: occlusal access opening restored with direct composite; group O+: as group O but with fibre reinforcement; group MOD: occlusal access opening and mesio-distal (MOD) cavity restored with direct composite; group MOD+: as group MOD but with additional fibre reinforcement. Pairwise comparisons of the fracture force among all groups was performed (95% confidence level). Fractures were classified in 4 groups depending on the type of fracture. Group O was the strongest (452.7N) and group MOD the weakest (292.4N). Fracture resistance was significantly different among all groups, except between groups O+ and MOD+. The majority of the unreinforced teeth displayed unfavourable fractures, while the reinforced teeth displayed more favourable fractures. The incorporation of glass fibre weakened endodontically treated but otherwise intact premolars; premolars with MOD restorations were stronger if reinforced with fibres. Fibre reinforcement led to more favourable fractures.
Gelingualiseerde okklusie in die Suid-Afrikaanse konteks.
(2002) Oberholzer, TG; Geerts, G
The search for the ideal artificial tooth arrangement that maximizes denture stability, comfort, aesthetics, and function has occupied the dental literature for many years and still continues to do so. Of the many occlusal schemes that have been presented to the dental profession, that of lingualized occlusion has emerged as one of the more popular. The popularity of lingualized occlusion stems from the simplicity and flexibility of the concept and from its wide application to clinical practice (Parr & Ivanhoe, 1996). The registration of a repeatable correct centric jaw relation is not always possible. We don't know whether the patient will use centric relation during normal function. It is therefore useful to provide the patient with some freedom of movement around centric. lingualized occlusion provides freedom in centric. For many dentists the arrangement of artificial denture teeth into balanced occlusion is difficult and time consuming. As a result this task is most often performed by the dental technician. In the South African countryside dental laboratories are often far away. If dentists perform the arrangement of the denture teeth, time and costs can be saved. The mounting of denture teeth in lingualized occlusion is simple and fast. This will motivate dentists to arrange denture teeth themselves, with obvious benefits for both the patient and the dentist. The School of Oral Health Sciences of the University of Stellenbosch teaches this concept to its undergraduate students in order to improve the prosthetic service to the large edentulous population of South Africa.
Perceptions of academic staff about mentoring in a Faculty of Dentistry in a public university in South Africa
(Scielo, 2021-07) Amosun, S; Geerts, G; Basson, R
INTRODUCTION: Mentoring programs contribute to the development and retention of academics in dental education. OBJECTIVES: To describe the perceptions of academic staff of the Faculty of Dentistry, University of the Western Cape, South Africa, about a funded pilot mentoring process. DESIGN: Cross-sectional, purposive sampling qualitative design. METHODS: Twenty mentees who had engaged in the funded mentoring process were targeted for semi-structured interviews, to describe their perceptions about the ongoing mentorship process, experiences in other mentoring processes, and expectations about future formal mentoring in the faculty. Quantitative data was analysed descriptively, while content analysis of the qualitative data was performed to identify themes FINDINGS AND CONCLUSIONS: Perceptions of eight mentees, aged 37 to 59 years and spent between 3 and over 20 years in the faculty, were categorized into two themes - 'A welcome initiative' and 'Mentorship seen as a holistic experience'. The program provided the much-needed space where mentees felt they could seek guidance for their development. Expectations from a future formal program included assistance in meeting institutional and personal demands. Participants' expectations were broader than what the pilot program offered, though the benefits reported were similar to earlier studies.
Plant Extract-Synthesized Silver Nanoparticles for Application in Dental Therapy
(MDPI, 2022-02-08) Ahmed, Omnia; Sibuyi, NRS; Fadaka, AO; Madiehe, MA; Maboza, E; Meyer, M; Geerts, G
Oral diseases are the most common non-communicable diseases in the world, with dental caries and periodontitis causing major health and social problems. These diseases can progress to systematic diseases and cause disfigurement when left untreated. However, treatment of oral diseases is among the most expensive treatments and often focus on restoration of form and function. Caries prevention has traditionally relied on oral hygiene and diet control, among other preventive measures. In this paper, these measures are not disqualified but are brought into a new context through the use of nanotechnology-based materials to improve these conventional therapeutic and preventive measures. Among inorganic nanomaterials, silver nanoparticles (AgNPs) have shown promising outcomes in dental therapy, due to their unique physicochemical properties and enhanced anti-bacterial activities. As such, AgNPs may provide newer strategies for treatment and prevention of dental infections. However, numerous concerns around the chemical synthesis of nanomaterials, which are not limited to cost and use of toxic reducing agents, have been raised. This has inspired the green synthesis route, which uses natural products as reducing agents. The biogenic AgNPs were reported to be biocompatible and environmentally friendly when compared to the chemically-synthesized AgNPs. As such, plant-synthesized AgNPs can be used as antimicrobial, antifouling, and remineralizing agents for management and treatment of dental infections and diseases.
Stress patterns around distal angled implants in the all-on-four concept configuration
(Quintessence Publishing, 2009-08) Begg, T; Geerts, G; Gryzagoridis, J
Purpose: The All-on-Four concept advocates immediate loading and the placement of distal implants at an angle. The purpose of this study was to do a qualitative descriptive analysis of stress patterns around the distal angled implant of the All-on-Four concept. Materials and Methods: Four photoelastic acrylic resin models, each with four implants simulating the All-on-Four configuration, were prepared. The two central implants were placed vertically and parallel in each model, and the distal implant on each side was placed at an increasing angle (0, 15, 30, and 45 degrees) in each model. The four implants were splinted by means of a cast metal bar. The photoelastic models were placed between two parallel anvils. Pairs of abutments were systematically subjected to a load by suspending 5-, 10-, and 15-kg weights from one of the anvils. Photoelastic analysis was accomplished using a circular polariscope. The fringe patterns produced in the photoelastic resin for each implant and load were photographed with a digital camera. Fringe concentrations and the highest fringe order were recorded and described for the apical, central, and coronal regions of the distal angled implant for each load scenario. Results: For the implants placed at 15- and 30-degree angles, little difference in stress patterns was observed between the central straight implant and the distal angled implant. For every load scenario and for all angulations, the lowest fringe order was recorded at the central region of the implant. The highest fringe order for the apical region was always higher than the highest fringe order for the coronal region of the implant. Markedly increased isochromatic fringe concentrations were observed in model 4, which had the distal implants placed at a 45-degree angle. Conclusion: Periimplant bone surrounding the 45-degree-angled distal abutment may be more prone to occlusal overload than bone surrounding implants with lesser tilts.
Surgical placement of implants – experiences, practices and opinions of South African Prosthodontists
(2012-04) Geerts, G; Naidoo, S
It is generally accepted that dental implant-treatment is "restorative" driven: the virtual blueprint of a prosthesis determines the position and number of implants to be placed. Competent interdisciplinary team-work is essential for the successful completion of implant-retained restorations. The purpose of this survey was to determine the experiences, practices and opinions in terms of the surgical placement of implants among South African prosthodontists. Methods: A questionnaire was e-mailed to a sample of South African prosthodontists. Data were collated and analysed using Epilnfo. Statistical significance was set at 0.05 and strength of association was determined by means of measurement of relative risk (RR) and chi-squared test or Fisher's exact test. Results: The response rate was 49%. The majority of respondents were male. Mean age was 50 years and all treated patients with implant-supported prostheses. Most implants were placed by non-prosthodontists (surgeons/ periodontists) and the majority of prosthodontists reported that they were generally satisfied with implant placement by other specialities. Six prosthodontists reported that they surgically place implants themselves. Of those not placing implants, five reported that they would like to do so. Younger prosthodontists, those who had attended short courses and those who considered their "surgical training" to be adequate, were more likely to place implants themselves or to want to do so. Conclusion: This survey identified areas for further research into the dynamics that may cause changing habits in the management of implants in prosthodontic practices, and carries the mplication that the scope of practice of the different specialities should be continuously evaluated and adapted, to the ultimate benefit of the patient.

Browsing by Author "Geerts, G"

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