UWCScholar :: Browsing by Author "Mulder, Riaan"

Browsing by Author "Mulder, Riaan"

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Accuracy and reliability of traditional measurement techniques for tooth widths and arch perimeter compared to CAD/CAM
(University of the Western Cape, 2018) Elmubarak, Mona; Hudson, Athol; Mulder, Riaan
Background: Plaster models form an integral part of the traditional orthodontic records. They are necessary for diagnosis and treatment planning, case presentations as well as for the evaluation of treatment progress. The accuracy of the measurements taken for space assessment is crucial prior to treatment planning. The introduction of digital models overcomes some problems experienced with plaster models. Digital models have shown to be an acceptable alternative for plaster models. Aim: The aim of the study was to determine the accuracy of traditional measurement techniques when compared to the CAD/ CAM measurements in the assessment of tooth widths and arch perimeter from plaster models. Method: The mesio-distal tooth widths and arch perimeter of thirty archived plaster models were measured using a digital caliper to the nearest 0.01 mm and divider to the nearest 0.1 mm. Corresponding digital models were produced by scanning them with a CAD/CAM (InEos X5) and space analysis completed by measurements using InEos Blue software. Measurements were repeated after 1 week from the initial measurement. The methods were compared using descriptive analysis (mean difference and standard deviation). Results: The operator reliability was high for digital models as well as the plaster models when the measurement tool was the digital caliper (analyzed using the Pearson correlation coefficient in the paired t-test). The mean values of tooth widths measurements of CAD/CAM, digital caliper and divider were 6.82 (±0.04), 6.94 (± 0.04) and 7.11 (± 0.04). There was a significant difference between the measurements made by the CAD/CAM and the divider. Additionally significant differences between the measurements by digital caliper and divider measurements (p < 0.05) were observed. No significant difference was found when comparing CAD/CAM to digital caliper. Positive correlation was displayed between CAD/CAM, digital caliper and the divider, but the measurements completed with the digital caliper had the highest correlation with the CAD/CAM. The difference was not significant between the aforementioned measurement tools (p > 0.05). Arch perimeter measurements showed no statistical significant difference between CAD/CAM, digital caliper and divider (p < 0.05). Conclusion: Archived plaster models stored as records can be converted to digital models as it will have the same accuracy of measurements. The value of doing a space analysis with the CAD/CAM system can be performed with similar reliability on the digital models as a caliper on plaster models.
Adapting an undergraduate dental objectively structured clinical examination (OSCE) during COVID‑19
(Health and Medical Publishing Group, 2021) Maart, Ronel; Ahmed, Rukshana; Mulder, Riaan
In the 5-year dentistry curriculum at the University of the Western Cape, South Africa (SA), prosthetic dentistry is presented as modules, starting in the 2nd year and culminating in the final module in the 5th year. Students are taught theory, and laboratory and clinical skills of removable (complete or partial) prostheses. Thus, acquiring psychomotor, clinical and problem-solving skills are an essential part of dental students’ education and training.[1] For trainee dentists, assessments include providing treatment for ‘real patients’, allowing them to demonstrate how theoretical knowledge of clinical procedures may be integrated with clinical skills in the clinical setting.[1] Teaching of clinical skills was completely interrupted during SA’s initial response to the COVID-19 pandemic, although theoretical teaching continued on various virtual platforms. Educators uploaded clinical cases, and narrated and scaffolded clinical procedures aligned with module outcomes to provide continued training for students, even though the impact in terms of clinical competence was limited.
Application of lasers in orthodontics
(South African Dental Association, 2017) Mulder, Riaan; Melman, Geoffrey; Karic, Vesna
Laser is the acronym for Light Amplification by Stimulated Emission of Radiation, a usage that dates back to approximately 50 years ago. In 1960, the first functioning laser was built by the American physicist Maiman at the Hughes Research Laboratories by using a synthetic ruby crystal made of aluminum oxide and chromium oxide. In general, lasers are composed of the three principal parts: an energy source, an active medium and a set of two or more mirrors that form a resonator. Properties such as wavelength are determined primarily by the active medium, which can be a gas, crystal or a solid-state conductor.
Are fissure sealants still relevant as a caries preventive measure?
(South African Dental Association, 2016) Mulder, Riaan
The groundwork for fissure sealants was completed in 1955 and lead to the introduction in 1971 of the Nuva-Seal Fissure Sealant by L.D Caulk. Since caries predominantly affects the pits and fissures of the teeth of children, these sealants have been shown to be a valuable preventive procedure. FS are cost effective and provide an ideal preventive measure for children who have restricted access to dental services. However the advent of dental lasers, caries detection systems, fluoride varnishes and novel adhesive systems may have displaced FS as a preventive measure of choice. The aim of this investigation was to establish whether FS remain a relevant preventive measure for the anatomically vulnerable fissure system.
Bio-active restorative materials as alternative pit and fissure sealants in pediatric and preventative dentistry: In vitro investigation
(MedCrave, 2017) Perchyonok, Tamara; Mulder, Riaan
BACKGROUND: It has been more than 40 years since the pit and fissure sealants were first used clinically. During this time, pit and fissure sealants have been shown to be effective in reducing the risk of occlusal caries. AIM: The aim of the investigation is to further develop and evaluate a versatile designed chitosan based bio-active materials on for use as bonding free fissure sealant/fissure protectors on permanent dentition and evaluate remineralization/demineralization capacity of the materials through pH cycling, as well as shear bond strength etch and no etch prototype as well as measurement of Vickers hardness of the newly designed materials and compare the property with the commercially available standard. RESULTS: In general there was an increase in bond strength of the enamel treated with the modified Premise containing nanodiamond: chitosan materials compared to the bond strength of the conventionally bonded teeth. It is seen that release of phosphorus into the dematerializing solution (i.e. loss of phosphorus from the samples) showed larger amplitude (from 600.2mg to 101.3 mg) than the uptake of phosphorus by the samples from the re-mineralizing solution (from 125.2 mg to 66.1 mg). Therefore, the treatment with chitosan seems to act more on the demineralization of tooth enamel with little effect on the remineralization process. Regarding the net phosphorus loss (net P loss), it can be seen that net demineralization occurs in all cases. However, the net amount of phosphorous released by the control group samples was significantly higher than those groups treated with chitosan. The net P loss for the control group was 475 mg of P, whereas the groups containing chitosan had a net P loss in the range of 30-182 mg. When a 1mm layer is assessed all the materials including the Premise control indicated a conversion of above 96%, which is the upper limit of the conventional fissure sealant material which makes the newly designed bioactive materials suitable for the application as fissure sealant materials. The important aspect of any newly designed/ developed restorative material is cytotoxicity as Grobler et. al [1] investigated the cytotoxic effect of nanodiamonds and also the effect of the incorporation in a dental material (Premise), who found a higher shear bond strength (p < 5%) after 3 months of Premise treated with nanodiamonds, chitosan, cyclodextrin (CD) and combinations thereof than for the control Premise. The sequence for the Vickers hardness was: CD (32.5) < nano (34.8) < CD Nano (38.8) < Premise (39) < Chitosan Nano (42.2). Nanodiamonds (92%) and the combination of chitosan + nanodiamonds (93%) showed little cytotoxicity. The shrinkage was lower for all the additions than for Premise alone. CONCLUSION: All modified Flowable bio-active materials can be further developed in effective fissure sealant material based on the acceptable in vitro results and cytotoxicity data.
Biomaterials and designer functional applications in oral cavity
(Nova Science Publishers, 2016-05-10) Perchyonok, Tamara; Mulder, Riaan
Dental biomaterials and natural products represent two growing research fields, revealing that plant¬derived compounds may play a role not only as nutraceuticals in affecting oral health but also in improving physicochemical properties of biomaterials used in dentistry. Recently, the role of free radicals in healthcare has attracted tremendous interest in the field of medicine, dentistry and molecular biology. Free radicals can be either harmful or helpful to the human body. When there is an imbalance between input and output of free radicals, a condition called “oxidative stress” develops. To counteract oxidative stress, the body has protective antioxidant mechanisms, which aid in lowering the incidence of various human morbidities and mortalities.
A call for action to safely deliver oral health care during and post COVID-19 pandemic
(MPDI, 2020) Mulder, Riaan; Farronato, Marco; Tadakamadla, Santosh Kumar
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak started just a couple of months ago and it grew rapidly causing several deaths and morbidities. The mechanism behind the transmission of the virus is still not completely understood despite a multitude of new specific manuscripts being published daily. This article highlights the oral cavity as a possible viral transmission route into the body via the Angiotensin converting enzyme 2 receptor. It also provides guidelines for routine protective measures in the dental office while delivering oral health care.
Cavity preparation using hard tissue lasers in operative dentistry
(South African Dental Association, 2017) Karic, Vesna; Mulder, Riaan; Melman, Geoffrey
A laser is a device that delivers coherent, monochromatic and collimated light as a form of energy. Most dental laser devices emit invisible light in the infrared portion of the electromagnetic spectrum. On May 7, 1997, the Food and Drug Administration (FDA) cleared for marketing in the United States the first erbium: yttrium - aluminum -garnet, or Er: YAG, laser for use in preparing cavities in the teeth of living human subjects.
Comparative in vitro study of selected physical properties of activa, cention n and vitremer
(University of the Western Cape, 2021) Mohammed Khair, Ro'aa Mohammed Jafar Mohammed; Mulder, Riaan
This study aimed to determine the association between dimensional change and surface roughness (Ra) of Vitremer, Activa and Cention N after immersing them into two different media: acidic and artificial saliva media for the period of a year. Measurements were made at 10 time intervals during the observation period.
A comparative study to determine the shock absorption ability of two popular mouth guards available on the South African market
(Electronic Doctor (E-Doc) Publishers & SADA, 2017) Mohamed, Nadia; Grobler, Sias Renier; Basson, N. J.; Osman, Yusuf Ismail; Mulder, Riaan
It is expected that most mouth guards will provide some level of protection to teeth. In this study a device was developed to measure the relative impact absorption of two different mouth guards (Proform, Type III vacuum-formed and Max, Type IV pressure laminate). Seven of each of the two types of mouth guards were made and each batch was exposed to between six and 10 impact trials.
Comparing cytocompatibility of two fluoride-containing solutions and two resin-based restorative materials—a pilot study
(Frontiers Media SA, 2024) Mulder, Riaan; Noordien, Naeemah; Potgieter, Nicoline
Background: Cytocompatibility should always be considered, especially if the surface of treated carious lesions is close to soft tissue or is accidentally exposed to the oral soft tissue by the clinician. Methods: The aim of the present study was to compare the cytocompatibility of two fluoride-containing liquids and two resin-containing restorative materials with buccal mucosa fibroblasts. The fluoride-containing materials were silver diamine fluoride and water-based silver fluoride. Results: The statistical analysis was completed by comparing the positive control growth of the buccal mucosa fibroblasts to the growth of cells exposed to various materials. The one-way ANOVA with Tukey’s HSD result was completed. All the assessed materials compared to the control wells for both the 24 and 48 h time intervals indicated a significant cytocompatibility result, except for the test wells with Stela (SDI) at the 24 h time interval. There was no significant difference between the step 2 liquids and the two dental materials in cytocompatibility at the 24 h interval. All four materials indicated no significant differences between the cytocompatibility of any dental materials for 48 h. Conclusion: The cytocompatibility assessment for Riva Star and Riva Star Aqua with the direct method in a full dispensing drop is not viable for step 1 of the fluoride-containing liquids. The use of Stela Light Cure is a suitable material that will be in contact with buccal mucosa as it showed potential for increased cytocompatibility compared to Riva Light Cure. Riva Star Aqua is more cytocompatible than Riva Star.
Comparing the curvature of orthodontic brackets to the buccal lnclination of the second maxillary premolar
(University of the Western Cape, 2019) Fakir, Yaseen; Mulder, Riaan
Background: The relationship between the curvature of the tooth and the curvature on the corresponding bracket is of vital importance. The closer the curvature of the base to that of the tooth, the closer adaptation it will assume. It will consequently have better adhesion, retention and distribute the forces on the tooth more efficiently in all dimensions. However, there is a lack of literature relating the buccal curvature of the tooth to the curvature of the corresponding orthodontic bracket. This dissertation investigated this relationship with the help of a novel methodology using Micro- Computed Tomography (Micro-CT). Aim: The aim of the study was to compare the buccal curvatures of the maxillary second premolars with the curvatures of three orthodontic bracket brands using a Micro-CT scanner. Methodology: The study sample included 33 randomly selected maxillary second premolars from archived orthodontic diagnostic models and corresponding orthodontic brackets from three manufacturers: Bioquick (Forestadent), Innovation (GAC) and Victory Series (3M Unitek). The sample was scanned using a Nikon Metrology XTH 225 ST X-ray micro-computer tomography scanner (Yokohama, Japan) at 100kV with a beam current of 200μA with an exposure of 1fps. The images were analysed on Volume graphics VG Studio max 3.2.5. The curvatures of the brackets at the mesial and gingival margin were isolated and the central angle of these curvatures were recorded in degrees. The corresponding curvature angles on the teeth were also recorded of each bracket. The angles of the brackets and the angles on the teeth were analysed to determine which bracket had the lowest angular difference. The angular differences were compared using a two-way ANOVA and a Bonferroni Pairwise Comparison. Results: The results of the study showed there to be no standardisation between angulations of the 3 bracket brands. It also confirmed the results in the literature which states the existence of a great variation in curvature between maxillary second premolars. A statistically significant interaction was found between the angles of the 3 brackets and the angles on the teeth p < 0.0001. The lowest angular difference for the joint 3 and 4 mm prescriptions at the mesial margin of the brackets was that of Victory Series -1.623 (±5.920) and Bioquick had the lowest angular difference for the joint prescriptions at the gingival margin 5.836 (±13.580). The difference at the mesial margin between the Victory series and Innovation was -4.494 (SE±1.681); p = 1 and between Victory series and Bioquick was -5.145 (SE±1.681); p = 1. Both were statistically insignificant. The difference between Bioquick and Innovation at the gingival bracket margin was 0.811(SE±1.681); p = 0, the difference between Bioquick and Victory series was 11.908 (SE±1.681); p = 0, both were statistically significant. Conclusion: The results indicated the best performing bracket at the mesial margin to be that of Victory series. This result was followed by Innovation and Bioquick who were closely matched with no significant difference. The best performing bracket at the gingival margin was Bioquick followed by Victory series and Innovation. The curvature of Innovation greatly underestimated the tooth curvature. The best overall angular difference was that of Victory series.
comparison of aerosolized hydrogen peroxide fogging with a conventional disinfection product for a dental surgery
(PMID, 2020) Sher, Marc; Mulder, Riaan
The study aimed to determine the efficacy of adding a 12% hydrogen peroxide dry hydrogen peroxide vapor fogger system as an additional layer of infection control in a dental surgery.
COVID-19 in dentistry - Ethical considerations
(South African Dental Journal, 2020) Maart, Ronel; Mulder, Riaan; Saadika, Khan
The reach of Coronavirus Disease - 2019 (COVID-19) has even reached the ethical guidelines for good practice from the Health Professions Council of South Africa (HPCSA).1 The health care worker should carefully consider the guidance outlined in several of the booklets as patient treatment has multiple dimensions where COVID-19 had impacted on clinical practice. Due to the nature of dentistry and aerosol generation, special care must be taken when treating healthy patients and patients that are carriers but do not realise that they are COVID-19 positive. COVID-19 transmission and aerosol dissemination may expose the practice team to hazards of infection. The risk is elevated when implementing aerosol generating procedures without any protective equipment. The oral health care worker (OHCW) and staff thus require the appropriate personal protective equipment (PPE) as suggested by country-specific guidelines, for example, The South African Dental Association (SADA).2 To this extent, practicing dentistry in the 21st century is complex3 and amidst the current COVID-19 pandemic the OHCW is presented with more pitfalls. As the pandemic is showing no sign of abating in SA, this has presented the OHCW with a range of additional ethical considerations. These dilemmas may be resolved in a variety of ways following an understanding of the basic knowledge of core ethical values and standards for good practice outlined by the HPCSA guidelines
COVID-19: Focus on masks and respirators – Implications for oral health-care workers
(2020) Mulder, Riaan; Layloo, Nazreen; Mulder van Staden, Sune
The emergence of the novel human coronavirus (Severe acute respiratory syndrome coronavirus 2; abbreviated as: SARS-CoV-2) generally known as COVID-19 is a global health concern.1 On 11 February 2020, the World Health Organization (WHO) named the novel viral pneumonia as “Corona Virus Disease” (COVID-19). The International Committee on Taxonomy of Viruses (ICTV) suggested this novel coronavirus be named “SARS-CoV-2” due to the phylogenetic and taxonomic analysis of this virus.2 Thus, both terms are utilised interchangeably in the literature. Undoubtedly, COVID-19 will change the way we practice dentistry with vast implications for Oral health-care workers (OHCW) and practice staff. Additionally, if rigorous safety protocols are not implemented based on a risk assessment outlined by the CDC, the dental practice can potentially become a nexus for disease transmission due to the high volume of aerosol production on a daily basis. Personal protective equipment (PPE), staff training and practice disinfection protocols have now especially become important in the light of the current pandemic. This is not a fight that one profession can fight alone, it requires joint efforts, it requires all stakeholders, it requires foresight and it requires us to put the health of the communities above all else.
COVID-19: The invisible risk to oral healthcare workers in dentistry
(José Frantz, 2021) Mulder, Riaan
Oral healthcare workers (OHCW) include any professional who can work in a dental practice setting, for example dentists, dental hygienists, dental therapists, dental assistants and denturists. Dentistry, as a profession, faces an overall elevated risk of exposure to a wide variety of infectious diseases originating from viruses and bacteria. There are numerous pathways of potential exposure to these micro-organisms. Additionally, OHCW carry a very high risk of Covid-19 transmission as a result of face-to-face communication and close proximity during dental procedures with patients, as the oral cavity and the respiratory tract can contain and transmit Covid-19.
Determination of orthodontic bracket and tooth adaptation using an X-ray micro-computer tomography scanner
(Elsevier, 2020) Fakir, Yaseen; Keanly, Colm; Mulder, Riaan
The determination of the orthodontic brackets’ adaptation to the curvatures of teeth is a difficult topic to study. The complexity arise due to the different designs of their fitting surfaces, margins and curvatures of orthodontic brackets. Teeth on the other hand have variation in their curvatures and the question remains how well an orthodontic brackets truly adapt to the teeth. Previous methods from the literature determined the curvature of teeth through the superimposition of circular templates onto dental plaster models as well as the use of acrylic arcs of various diameters.
Extra-oral suction
(MDPI, 2023) Noordien, Naeemah; Mulder-van Staden, Suné; Mulder, Riaan
Oral health care workers (OHCW) are exposed to pathogenic microorganisms during dental aerosol-generating procedures. Technologies aimed at the reduction of aerosol, droplets and splatter are essential. This in vivo study assessed aerosol, droplet and splatter contamination in a simulated clinical scenario. The coolant of the high-speed air turbine was colored with red concentrate. The red aerosol, droplets and splatter contamination on the wrists of the OHCW and chests of the OHCW/volunteer protective gowns, were assessed and quantified in cm2 . The efficacy of various evacuation strategies was assessed: low-volume saliva ejector (LV) alone, high-volume evacuator (HV) plus LV and an extra-oral dental aerosol suction device (DASD) plus LV. The Kruskal– Wallis rank-sum test for multiple independent samples with a post-hoc test was used. No significant difference between the LV alone compared to the HV plus LV was demonstrated (p = 0.372059). The DASD combined with LV resulted in a 62% reduction of contamination of the OHCW. The HV plus LV reduced contamination by 53% compared to LV alone (p = 0.019945). The DASD demonstrated a 50% reduction in the contamination of the OHCWs wrists and a 30% reduction in chest contamination compared to HV plus LV. The DASD in conjunction with LV was more effective in reducing aerosol, droplets and splatter than HV plus LV.
In vitro analysis of techniques that alter the surface hardness of a glass ionomer restorative material
(Jaypee Brothers Medical Publishers, 2019) Mulder, Riaan; Noordien, Naeemah; Rossouw, Shaun
Ab s t r A c t Aim: The aim of this in vitro study was to compare the eect of dierent manipulation techniques on the surface hardness of ChemFil Rock glass ionomer.Materials and methods: The changes in Vickers surface hardness ( VH) of ChemFil Rock were evaluated after the application of ve manipulation techniques and compared with one control group (n = 60). The manipulation techniques included: nger pressure set, electronic piezo producing a high frequency set, air piezo producing a low frequency set, heat-set achieved with a curing light and the last technique was a combination of electronic piezo followed by heat-set. Standard set was the control.Results: The average surface hardness for the standard set was 49.5 VH. No statistical dierences were demonstrated when the means were compared for nger pressure set (49.2 VH) or the air piezo set (48.49 VH) with standard set. The electronic piezo (54.21 VH) and the heat-set (57.5 VH) had an increased mean surface hardness when compared to other techniques. Heat-set had the highest surface hardness demonstrating a signicant statistical dierence when compared with standard set, nger pressure set, air piezo set as well as the combination of electronic piezo (p < 0.05).Conclusion: The surface hardness of the glass ionomer cement (GIC) material assessed in this study can be predictably improved by applying the heat-set technique. A command set can be achieved with the electronic piezo or the air piezo, however, the surface hardness will only increase with the use of the electronic piezo.
In vitro analysis of techniques that alter the surface hardness of a glass ionomer restorative material
(Original research, 2019) Mulder, Riaan
Glass ionomer cement as restorative materials are advantageous in pediatric restorative dentistry. The main advantages of GIC include fluoride release up to 50 μg/cm and a chemical adhesion to the tooth structure

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