UWCScholar :: Browsing by Author "Geerts, Greta"

Browsing by Author "Geerts, Greta"

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Aesthetic clasp design for removable partial dentures: A literature review
(South African Dental Association (SADA), 2005) Khan, Saadika; Geerts, Greta
Removable partial dentures (RPD) are an effective and affordable treatment option for partial edentulism. If the main reason for seeking treatment is the need for improved aesthetics, treatment should be geared towards achieving this goal. This article is the result of a literature study on aesthetic clasp design for the conventional RPD. In this context, the position of the clasp on the tooth, clasp types, clasp material and alternative methods of retention are reviewed. Although published in reputable journals, the authors report that many articles published on this subject are of a descriptive nature and lack scientific evidence. Therefore, clinicians are encouraged to be critical in their interpretation of literature and the application of published information in their clinical practices.
An in-vitro study of a modified bioactive orthodontic cement
(University of the Western Cape, 2017) Moodley, Tashia; Geerts, Greta
Introduction: Demineralization of the enamel surface adjacent to bonded orthodontic brackets during treatment is an ongoing drawback, especially when manifested as white spot lesions. Enamel demineralization is initiated by organic acids produced mainly by Streptococcus mutans. A favourable substitute is the development of orthodontic bonding agents with antibacterial or microbial properties. Chitosan is an interesting candidate in this respect. Thus, the rationale of this study was to incorporate chitosan into an orthodontic cement to create a novel orthodontic cement and assess whether the incorporation of chitosan to an existing orthodontic cement would affect its biological and physical properties.
Bonding of acrylic denture teeth to resin denture bases
(South African Dental Association, 2012) Geerts, Greta; Martin E.
Anterior teeth debonding from dentures is a common prob lem. This study tested the bond strength of denture teeth to two types of denture res1n, with and without grooving the ridge-lap surface. Bond strength and fracture type of three d1fferent groups were compared: 1 Teeth bonded to heat-cured polymethyl methacrylate (PMMA); 2. Teeth bonded to pour-type PMMA: 3. Grooved teeth bonded to pour-type PMMA. Specimens were manufactured following ISO standard 22112. Force values at failure were analysed using one-way analy sis of variance, us1ng the mixed procedure with confidence interval of 95%. Types of failure were Identified as adhes1ve, cohesive or combination. Indescending order, mean failure forces were 418.551\J (Group One), 367.551\J (Group Two) and 290.051\J (Group Three). There was no significant difference between the means of groups 1 and 2 (p=0.0627). Group Three differed from both other groups (p<0.001). Groups One and Two showed pre dominantly cohesive fractures within denture teeth (83% and 72% respectively): group Three showed predom1nant1y cohe sive fractures withtn the denture PMMA (75%) Wtthout ridge-tap modiftcat1on, the bond strengths of den ture teeth to pour-type and heat-cured denture res1n were Similar. Failures were predominantly of cohesive nature with1n the teeth themselves. Grooving the ridge-tap reduced fracture resistance and ted to breakages predominantly in denture PMMA.
A comparative study between thermoplastic and conventional removable partial denture designs
(University of the Western Cape, 2019) Farao, Warren Emile; Geerts, Greta
Three 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.
Comparing patient-based outcomes related to neutral zone and conventional mandibular dentures: A systematic review
(South African Dental Association, 2017) Geerts, Greta; Khan, Saadika Begum
Neutral zone mandibular dentures are considered tobe superior to conventional complete dentures.Conventional complete dentures (CD) have been the most common and only treatment modality for rehabilitation of edentulousness until the introduction of dental implants. Implant-retained or implant-supported prostheses have been proven to be superior to conventional CDs in terms of patient-based outcomes (PBOs).' However, implant therapy may be out of reach of patients due to a variety of reasons.
Complete denture occlusion: intra and inter observer analysis
(University of Western Cape, 2014) Mpungose, Sandile Khayalethu Derrick; Geerts, Greta
Aim: 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.
Conformity of removable partial denture designs to agreed principles based on materials used - A preliminary study
(South African Dental Association, 2020) Farao, Warren; Geerts, Greta
Removable partial denture (RPD) designs may differ based on types of materials used. The aim of the study was to investigate how a sample of non-metal clasp (NMC), acrylic and metal RPD designs complied with biomechanical design principles. This cross-sectional study examined 60 clinical designs of NMC, acrylic and metal RPDs at 3 commercial dental laboratories in the Cape Town Metropole, at the stage when the dentures were ready for transport to dentists.
Development of academic staff in faculties of dentistry by means of mentorship programs: Protocol for a scoping review
(JMIR Publications, 2021) Amosun, Seyi; Kimmie-Dhansay, Faheema; Geerts, Greta
Globally, the demands on dental educators continue to diversify and expand. Due to their importance and value, mentoring programs have been acknowledged as a means of recruiting, developing, and retaining academics in dental education. Objective: This protocol is for a scoping review that aims to identify the goals of mentoring programs for academic staff in dental faculties and determine how these programs were structured, delivered, and evaluated.The review will be performed in accordance with the Joanna Briggs Institute’s methodology for scoping reviews, which covers both qualitative and quantitative scientific literature as well as grey literature written in English and published between 2000 and 2020. The databases will include PubMed, Ovid, the Educational Resources Information Center database, Science Direct, Scopus, Google Scholar, Trove, Web of Science, Openthesis.org, and the website of the American Dental Education Association. A manual search will also be conducted by using the reference lists of included studies to identify additional articles. Working independently, the authors will participate iteratively in literature screening, paper selection, and data extraction. Disagreements between the reviewers will be resolved by discussion until a consensus is reached or after consultation with the research team. Key information that is relevant to the review questions will be extracted from the selected articles and imported into a Microsoft Excel file. The PRISMA-ScR (Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews) will be used to guide the reporting of this protocol.
The effect of different reinforcements on the fracture toughness of materials for interim restorations
(Elsevier, 2008) Geerts, Greta; Overturf, Jan-Hendrik; Oberholzer, Theunis
STATEMENT OF PROBLEM. Fracture of an interim fixed partial denture (FPD) may jeopardize the success of the interim prosthodontic treatment phase and cause patient discomfort. PURPOSE. The purpose of this study was to compare the fracture toughness of a polymethyl methacrylate (PMMA) resin and a bis-acryl composite (BAC) resin reinforced with stainless steel wire, glass, and polyethylene fiber. MATERIAL AND METHODS. Four groups (n=13) of each of the 2 materials were prepared for the single-edge 3-point-bending test. Three groups had the different reinforcements, and the group without reinforcement served as control. Using a universal testing machine, peak load to fracture was recorded and fracture toughness (KIC) was calculated in MNm-1.5. Median KIC values were compared by means of nonparametric ANOVA (Kruskal-Wallis test, α=.05). RESULTs. For the controls, the fracture toughness for PMMA resin (KIC=27.9) was significantly lower (P<.01) than for BAC resin (KIC=31.2). Glass fibers and stainless steel wire reinforcements produced significantly higher fracture toughness for both PMMA (KIC=34.4, P<.01, and KIC=39.0, P<.001, respectively) and BAC resin (KIC=42.3, P<.001, and KIC=44.0, P<.001, respectively), but the polyethylene fibers did not (KIC=33.1, P>.10, for BAC resin and KIC=25.8, P>.10, for PMMA resin). There was no significant difference between the fracture toughness of the wire and glass fiber reinforcements for both interim materials (P>.10 in both instances). CONCLUSIONS. Of the 3 reinforcement methods evaluated, wire and glass fiber reinforced the PMMA and BAC resin materials best.
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 Dentistry
One 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.
Fracture resistance of endodontically treated maxillary premolars restored with horizontal glass fiber post: An in vitro and finite element analysis
(University of the Western Cape, 2022) Abdulrab, Saleem; Geerts, Greta
Maxillary premolars are subjected to a combination of vertical and lateral occlusal forces. Furthermore, premolars present with an anatomical shape and unfavorable crown to root ratio, making them more prone to fractures than other posterior teeth. When endodontic treatment is combined with mesio-occluso-distal (MOD) cavities, the susceptibility to fracture increases.
The impact of new complete dentures on oral health-related quality of life
(South African Dental Association, 2007) Adam, R.Z.; Geerts, Greta; Lalloo, R.
OBJECTIVE: To investigate the relationship between complete dentures and oral health-related quality of life (OHRQol). METHOD: Seventy-six patients were conveniently selected from the waiting list for complete dentures. At the first visit (pre-treatment) the patients were interviewed using the Ora Health Impact Profile for Edentulous Patients (OHIP-EDENT). Sixty-three of these patients were interviewed telephonically 2 to 3 months after receiving their new complete dentures (post-treatment). RESULTS: Mean domain scores were significantly lower post treatment for psychological discomfort and disability, social disability and handicap. CONCLUSION:This study shows that after the provision of a new set of complete dentures the OHRQoL of patients improved significantly on four of the seven domains for the first 2 to 3 months post-insertion.
An implant-supported auricular prosthesis: a team effort between two South African tertiary institutions
(South African Dental Association, 2002) Geerts, Greta; Lombard, G.
Primary osseo-integration with cranio facial implants is so reliable that it may be considered routine. Arcu ri ef nl.' reported that the use of titan ium endosseous screw implants proved to be a successful, predictable, and quali ty-of-life-enhancing technique for prosthetic anchorage in the midface region. Nishimura el nl.' reported a 100% success rate for implants used for auric ular prosth eses.This may be part ly the resu lt of a generous thlckness of compact bone in the craruu m . The Division of Prosthodontks, School for Oral Health Sciences, Universi ty of Stellenbosch and the Department of Dental Services, Faculty of Scien ce, Peninsula Technicon collabora ted to provide a maxillofacial serv ice and to create a training opportunity for senior undergraduate s at the two tertiary institutions. This article describes the prosthodontic management of an implant-supported auricu lar prosthe sis.
The influence of horizontal glass fiber posts on fracture strength and fracture pattern of endodontically treated teeth: A systematic review and meta-analysis of in vitro studies
(Wiley, 2022) Abdulrab, Saleem; Geerts, Greta; Al-Maweri, Sadeq Ali
This systematic review and meta-analysis aimed to summarize available evi-dence regarding the effect of horizontal glass fiber posts (HGFPs) on fracture strengthand fracture pattern of endodontically treated teeth (ETT) compared to controls withoutHGFP. The review protocol was registered on the OSF registries.Literature searches were conducted in MEDLINE/PubMed, Scopus, Web ofScience, Embase, Google Scholar, and ProQuest for all relevant studies published upto February 2022. All in vitro studies that assessed the influence of HGFPs on fracturestrength and fracture pattern of ETT whether mesio-occluso-distal or mesio-occlusalor DO cavities were considered eligible. Review Manager (RevMan) was used forthe meta-analysis. Subgroup and funnel plot analyses were also performed. Qualityassessment was conducted by two independent reviewers.
The influence of mixing ratio on the fatigue behaviour of fibre reinforced polymers
(University of the Western Cape, 2013) Stuhlinger, Martin Ernst; Geerts, Greta
Statement of the problem: Fibre reinforcement of polymethyl methacrylate (PMMA) denture base material is known to improve the strength, as well as the fatigue behavior, of the material. The powder liquid (P/L) ratio of PMMA is often changed to modify the handling properties of the material. Little is known about the effect of this deviation from manufacturer’s guidelines on the fatigue behaviour of the fibre reinforced product. Purpose: This study compared the flexural strength (FS) of PMMA reinforced with glass fibre using different P/L ratios, before and after cyclic loading. Methods and materials: Three groups, with 50 glass fibre reinforced (everStick nonimpregnated fibers) heat-cured PMMA resin (Vertex Rapid Simplified) specimens each, were prepared using a custom-made template (dimensions 10x9x50mm). Each group had a different P/L ratio: the control group (100%) had the manufacturer’s recommended ratio; the 90% and 80% groups had reduced P/L ratios (by weight).Twenty five specimens from each group were subjected to a 3-point bending compression test using a universal testing machine. The remaining 25 specimens from each group were subjected to cyclic loading (104 cycles) before compression testing. The (FS) was calculated using the highest force (Fmax) before specimen failure. Flexural strength was calculated using the equation: FS=3WL/2bd2. Within each group, median FS values before and after cyclic loading were compared by means of a non-parametric analysis of variance. The Aligned Ranks Transform method was used for the analysis. Statistical significance was set at p=0.05. Results: The Fmax (N) of the control (100%), 90% and 80% groups fatigued and unfatigued were 100%: 1665 (fat), 1465 (unfat); 90%: 1679 (fat), 1548 (unfat) and 80%: 1585 (fat), 1467 (unfit) respectively. There was no significant interaction between Mix ratio and Fatigue state, and the 80% mix had a significantly higher mean than either the 90% or 100% mix (with differences of about 0.3 units for both). The Fatigued state had a higher mean than the Un- fatigued state by about 6.0 units. Using FS (MPa) it was found that the fatigued 80% mix specimens had the highest value. The FS MPa of the control (100%), 90% and 80% groups fatigued and un-fatigued were 64.3, 60.6; 66.9, 65.6 and 70.2, 69.3 respectively. The fact that fatiguing strengthened the specimens merits further research. When observing the broken specimens it was found that there was a complete debonding of the fibres and the PMMA. Conclusion and clinical relevance: a) Fibre: The benefit of using glass fibre bundles to reinforce prostheses fabricated using heat cured PMMA is questionable due to problems with bonding between the fibre bundles and the heat cured PMMA resin. b) Fatiguing: An average person chews 107 times during a 3 year period. A limited period of average masticatory forces should not have a detrimental effect on prostheses made from heat cured PMMA resin. c) Mix ratio: Within the normal parameters of laboratory techniques the mix ratio of PMMA resin had no significance on the fracture resistance of the prostheses. Due to the high cost of the fibres used for the reinforcement and the limited success and insignificant results achieved in this study, this researcher cannot recommend using Stickbond or Stick fibers for the reinforcement of dentures made with heat cured PMMA resin.
The influence of powder liquid ratio on the flexural strength of fibre reinforced acrylic resin material
(South African Dental Association, 2009) Geerts, Greta; du Rand, M.
Introduction: Often the powder liquid (P/L) ratio of polymethyl methacrylate (PMMA) resins is changed to modify the handling properties of the material. While it is known that this may influ ence the mechanical properties of unreinforced PMMA resin, little is known about its effect on fibre reinforced resin. Purpose: The purpose of this study was to determine how different P/L ratios influence the flexural strength (FS) of a glass fibre reinforced autopolymerizing PMMA resin used for fabr icating fixed partial dentures. Results: FS values of all reinforced subgroups were significant ly higher than the values of the unreinforced subgroups (pO.OS) . Within the reinforced group there was a sig nificant difference between the control group, which had a higher median FS value than the two other subgroups (p
A Randomized Crossover Trial Comparing Patient preference for Mandibular Complete Dentures Made with Two Different Techniques: A Short-Term Follow-Up
(Quintessence Publishing, 2017) Geerts, Greta
Purpose: The objective of this trial was to compare short-term patient preference for two mandibular complete denture (CD) fabrication techniques: neutral zone (NZ) and conventional (CV). Materials and Methods. A prospective, within-subject, randomized crossover trial was performed on a sample of 37 edentulous patients with CD experience. Two new sets of CDs were made for each patient, one set with a CV and one with a NZ mandibular denture. After consecutively wearing each set for at least 2 months after the last adjustment visit, patients indicated preference (CV, NZ or none). Associations and comparisons were made using the generalized linear model (GLM) and Fisher exact test between preference and sex, age, period of edentulousness, tissue quality, prosthodontic diagnostic index (PDI) and oral health-related quality of life (OHRQoL) differences of the two interventions assessed using the 20-item oral health impact profile (OHIP-20). Significance level was determined at P= .05. Results. A total of 15 (40%) patients preferred NZ, 8 (22%) preferred CV dentures and 14 (38%) had no preference. Although more women preferred NZ over CV dentures (50% versus 27%), difference in preference according to sex was not significant (P= .359). Neither was difference in preference and PDI scores significant (P= .603). Preference could not be strongly associated to period of edentulousness, age, tissue scores and differences in OHIP-20 scores (P> .05), except for OHIP-20 scores and NZ preference (P< .001). Better fit, comfort and eating were reasons why patients preferred a type of denture. These reasons were identified for both types of denture. Appearance and speech were not identified as reasons for a particular preference. Conclusions. Based on preference expressed by patients, there is no difference between NZ and CV mandibular dentures. Denture preference could not be related to patient variables over the study’s time frame.
Relationship of TMD diagnosis and self-reported biopsychosocial status of patients attending the TMD clinic
(University of the Western Cape, 2018) Ahmed, Omer Abdelrahim Sidig; Geerts, Greta
Background: This study aimed to investigate a possible relationship between the diagnosis of TMD and biographical, psychological and social status of patients. Materials and Method: All records of patients who attended the TMD clinic in the Mitchells Plain Oral Health Centre in the period from January 2015 to July 2018, and who were examined according to the DC/TMD protocol, were collected. All diagnostic observations, as well as their biographical, psychological and social data were recorded. Statistical analysis was performed by means of comparisons and association analysis among data to evaluate if there were any statistically relevant associations or differences.
The significance of sub-threshold symptoms of anxiety in the aetiology of bruxism
(South African Journal of Psychology, 2010) Basson, Reneda; Mwaba, Kelvin; Rossouw, Roelof; Geerts, Greta; van Wyk Kotze, Theuns; Stuhlinger, Martin E.
Bruxism is an oral parafunctional habit involving clenching and grinding of the teeth. It occurs mainly unconsciously, diurnally and/or nocturnally. It is considered an important contributory factor in the aetiology of myofacial pain (MFP) and temporomandibular disorders (TMD). The etiology of bruxism is considered to be multifactorial, involving physiological and psychological factors. The aim of the study was to examine the relationship between the sub-threshold symptoms of anxiety and bruxism using a spectrum model. Firstly, levels of anxiety and stress were determined using the Spielberger State Trait Anxiety Inventory (STAI) and the Kessler-10 (K-10). Secondly, a tooth wear score was determined by means of a clinical examination, intra-oral photographs and dental casts. Thirdly, bruxism was rated on an ordinal scale according to specified bruxism criteria. A dualistic trend in the relationship between sub-threshold symptoms of anxiety, stress and bruxism was observed in the results. In approximately half of the subjects with higher than average anxiety and stress scores, bruxism behaviour was found. This indicates the possibility of two groups with separate relationships. The dentist could play a role in recognizing that a patient may be experiencing stress or anxiety, expressed through bruxing behaviour and refer the patient for therapy or counselling. An understanding of the psychological factors involved in the etiology of bruxism could encourage a more holistic approach to the treatment of patients with signs of bruxism.
Temperature changes along a dental implant
(Quintessence Publishing, 2011) Geerts, Greta; Patel, Zaheed
AIMS: The aims of this in vitro study were to analyse temperature changes along the surface of a dental implant and to establish the abutment temperature that could cause the critical 47ºC/1min threshold at implant level. METHODS: Eight thermocouples were attached at 1 mm intervals to an abutment/implant configuration. The model consisted of 2 compartments in a thermostatically controlled environment. The upper compartment represented the oral cavity with the abutment, which was exposed to 20ml of hot water. The temperature at each thermocouple was logged over a period of 10 minutes. A Spearmans Rank correlation test and logistic regression model were used for the statistical analysis of the time/temperature databases and the estimation of the ‘effective dose 50’ for the abutment (95% confidence interval). RESULTS: For 53 test series, the abutment temperature ranged from 52.80ºC to 71.72ºC. There was a positive correlation between the maximum temperature at implant level and the temperature of the abutment. The 47ºC/1min threshold was reached 31 times at the most cervical implant level and decreased in frequency further away from the heat source (14, 6, 3, 1 and 1 times resp.) The ED50 was estimated at 62.3ºC. This means that for an abutment temperature of 62.3ºC there was a 50% chance that 47ºC for 1 minute at implant level would be reached. CONCLUSION: This in vitro study supports the hypothesis that abutment temperature is transmitted to an implant. Although results of in vitro studies should be interpreted with caution, clinicians should be aware of temperature changes along implants and the potential risk associated with it.

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