Theses and Dissertations (Odontology)

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    An in vitro, SEM and micro-CT comparison of dentinal tubule penetration and void formation by four bioceramic sealers in premolars
    (University of Pretoria, 2023) Arnold, Samantha; Buchanan, Glynn Dale; lotive.shabalala@up.ac.za; Shabalala, Lotive
    Introduction: Bioceramic sealers are receiving substantial attention because of their favourable physicobiological properties. Studies have shown that the use of materials containing calcium-silicates results in the formation of a crystalline structure similar to tooth and bone apatite, which is favourable in the healing of endodontic lesions. Aim: The aim of this study was to compare the sealing ability of four bioceramic sealer materials, available commercially in South Africa, by measuring the formation of voids at three levels (coronal, middle and apical). Materials and Methods: In this study, four different bioceramic sealers (BioRoot RCS, CeraSeal, TotalFill, and AH Plus Bioceramic [BC]) were compared. Single rooted premolars were included. Coronectomies were performed on each tooth and the root canals were prepared using reciprocating instruments. The canal was then obturated using a single gutta-percha point and one of the four specified root canal sealers. The sealers were allowed to set, after which the obturations were analysed and compared using microcomputed tomography (micro-CT) to evaluate void formation. Results: For the overall average of all three positions (coronal, middle, and apical), the mean surface area of voids of the four sealers did not differ significantly (p>0.05). The overall median surface area of voids for AH Plus BC and BioRoot differed significantly (p=0.049). Conclusion: None of the four tested bioceramic sealers demonstrated void-free fillings and voids were found in all samples to varying degrees.
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    Comparing obturation quality and preparation times of different pulpectomy preparation techniques in primary molars – an In vitro study
    (University of Pretoria, 2023) Vorster, Martin; Van der Vyver, Petrus Jacobus; ilana.middleton@up.ac.za; Middleton, Ilana
    The purpose of this in vitro study was to evaluate and compare obturation quality and preparation times after root canal shaping between manual, rotary and reciprocating files during pulpectomy treatment in primary molars. Sixty extracted, human, primary mandibular second molars were randomly divided into three experimental instrumentation groups, Group 1: Manual stainless steel (ss) K-files (ISO size 20-35), Group 2: Rotary ProTaper Gold SX file and Group 3: Reciprocating WaveOne Gold Medium file. The mesiobuccal root canals of all the teeth were prepared and obturated with an iodine paste, Vitapex. The obturation quality was assessed using post-operative radiographs and a scoring criteria classified as “Good”, “Average”, “Poor” or “Failed”. Preparation times were recorded in seconds with a digital stopwatch and compared between different preparation groups. The quality of obturation results showed superior obturation quality in the ProTaper Gold SX and WaveOne Gold Medium groups. Although the ProTaper Gold SX group performed the best, no statistically significant difference was observed between the ProTaper Gold SX and WaveOne Gold Medium groups. The ss K-file group resulted in the most “Poor” and “Average” outcomes. The results of the preparation times showed the mean preparation time values within the ss K-file group to be significantly higher (186.4 s) than preparation time values within both the ProTaper Gold SX (29.6 s) and WaveOne Gold Medium groups (30.5 s). The preparation times of samples in the ProTaper Gold SX group and the WaveOne Gold Medium group did not differ significantly. Within the limitations of this study, it can be concluded that the preparation times with the ProTaper Gold SX and WaveOne Gold Medium groups were statistically significantly faster than the manual ss K-file group. Rotary and reciprocating file instruments are also effective alternatives to conventional manual preparation with ss K-files. Rotary and reciprocating file instruments resulted in better obturation quality during pulpectomy treatment in primary molars compared to manual instrumentation. Thus, it can be concluded that the rotary and reciprocating file systems results in the fastest preparation time as well as superior obturation quality.
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    Root and canal configurations of mandibular molars using CBCT, with an emphasis on middle mesial canals
    (University of Pretoria, 2020) Warren, Nichola; Buchanan, Glynn Dale; shereetredoux@gmail.com; Tredoux, Sheree
    Introduction: An extensive knowledge of dental root and canal anatomy is essential to clinicians performing endodontic treatment. It is well-known that dental anatomy may be complex and display significant variation. Aim: The aim of the present study was to classify the root number and the root canal configurations of human mandibular first and second molars in a South African sub-population using CBCT. Materials and methods: The study design was a retrospective cross-sectional descriptive study. The sample size included 753 molars. The CBCT images of each individual mandibular first and second molar were evaluated in coronal, sagittal and axial views. Classification of the canal configurations of each root was made using the Vertucci classification system, including the additions proposed by Sert and Bayirli. Classification of root number was described as one, two, three, or four-roots. Results: Root anatomy: Two-rooted configurations were demonstrated in the majority of first and second molars (98.7% and 94%). One- and three-rooted molars were rare with a prevalence ranging from 0.3% to 2.9%. Half of all three-rooted molars presented with two distinct mesial roots. Four-rooted molars were found in second molars only (0.5%). Canal anatomy: The most common canal type in the mesial roots of mandibular first and second molars was Type IV (50% and 38%) followed by Type II (21% and 24%). The most common canal configuration in the distal roots of the first and second molars was Type I (50% and 81%) followed by Type V (20% and 10%). More than two mesial canals in mandibular first and second molars were present in 21% and 17% of the sample. More than two distal canals were demonstrated in first and second molars in 7% and 2% of the sample. C-shaped canal systems were found in 0.5% of first molars and 7.7% of second molars. Sex and age had no correlation to root or canal configurations. Conclusion: More than two mesial canals were found in about one-fifth of the sample. It is important for clinicians to be aware that a number of mandibular molars may present with more intricate anatomy than expected during endodontic treatment and that this may affect treatment outcomes.
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    Evaluation of Root Canal Transportation Centering Ratio and Remaining Dentine Thickness in Curved Root Canals Prepared with WaveOne Gold in Combination with Different Glide Path Techniques
    (University of Pretoria, 2017) Van der Vyver, Petrus Jacobus; martin.vorster@up.ac.za; Vorster, Martin
    The aim of this in vitro study was to investigate various glide path preparation instruments followed by root canal preparation with the reciprocating Primary WaveOne Gold instrument in curved mesial root canals of extracted human mandibular molars. Micro Computed Tomography (micro-CT) was used. Canal transportation, centering ability and effect on remaining dentine thickness were evaluated over the apical, midroot and coronal levels (3 mm, 5 mm and 7 mm from the root apex). In addition, preparation times for glide path preparation and final canal preparation with the Primary WaveOne Gold instrument were also recorded and compared. Sixty curved mesio-buccal root canals were randomly divided into four groups. These groups were Group 1: no further glide path preparation (n=15); Group 2: glide path enlarged with the use of pre-curved size 10,15 and 20 stainless steel K-files (n=15); Group 3: manual glide path enlargement with a size 10 K-file and further preparation with rotary PathFiles no.1-3 (n=15); and Group 4: manual glide path enlargement with a size 10 K-file and further preparation with the reciprocating WaveOne Gold Glider (n=15). Micro-CT was used to scan teeth before and after glide path preparation. The final canal preparation was done with the Primary WaveOne Gold instrument after which all 60 specimens were scanned again by means of micro-CT. The three-dimensional images obtained before instrumentation, after glide path preparation and again after final canal preparation with the Primary WaveOne Gold instrument were reconstructed and interpreted. Centering ratio values, canal transportation, remaining dentine thickness as well as glide path and final canal preparation times were recorded and compared between the four glide path groups with the use of a one-way analysis of variance (ANOVA) for parametric and Kruskal-Wallis H test for non-parametric comparisons. Statistical significance was set at p< 0.05. PathFiles performed most favourably when mean centering ratios were compared over all three levels from the root apex. However, no statistically significant difference in the mean centering ratios was found after glide path preparation when K-files, PathFiles and the WaveOne Gold Glider were compared. Mean combined transportation over the apical, midroot and coronal levels after glide path preparation was statistically significantly higher in the K-file preparation groups compared to the PathFile and WaveOne Gold Glider groups. There was no statistically significant difference in the mean combined centering ratios or transportation values of the various glide path groups in combination with the Primary WaveOne Gold instrument over the apical, midroot and coronal levels. Although not statistically significant, the highest mean transportation values were seen in the group where no glide path was prepared prior to final canal preparation with the Primary WaveOne Gold Instrument. All glide path groups performed similarly in evaluation of preservation of dentine when they were used in combination with the Primary WaveOne Gold instrument. Not having a prior glide path resulted in the most dentine thickness reduction after final canal instrumentation with the Primary WaveOne Gold instrument. Glide path preparation was statistically significantly fastest with the use of the WaveOne Gold Glider (p<0.0001). Having no prior glide path preparation resulted in statistically slower final canal preparation in combination with the Primary WaveOne Gold instrument compared to the other three glide path preparation groups (K-files, PathFiles and WaveOne Gold Glider) (p<0.0001).
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    Decontamination and use of endodontic hand files in dental practice in Pretoria
    (University of Pretoria, 2017) Warren, Nichola; u26031206@tuks.co.za; Buchanan, Glynn Dale
    The risk of cross-contamination validated the need to assess the adequacy of cleanliness of dental instruments following decontamination procedures. Neither the extent of single-use nor the efficacy of decontamination of endodontic hand files following routine cleaning and sterilisation procedures in South Africa was known. The first aim of this study was to determine the amount of visible debris left on endodontic hand files collected from dental practice in Pretoria, South Africa, following the application of routine decontamination procedures. Secondly, the study aimed to determine the prevalence and attitudes regarding the single-use of these instruments. Twenty-seven dental practices voluntarily took part in this study. Each participant was requested to submit 15 previously used and decontaminated endodontic hand files. A short questionnaire regarding the single-use of endodontic files was completed by participants. A coding system was used to guarantee the anonymity of the participants. Files were examined for the presence or absence of remnant debris using a stereomicroscope at ten and 40 times magnification. A novel scoring system was used to rate the position of the debris. Statistical evaluation of the data estimated the frequency and proportions of debris on the endodontic hand files, in each scoring position. Cohen’s Kappa statistic was used to assess the repeatability of the scoring system. Four hundred and one endodontic hand files were collected from 27 participants. It was found that 94% of the samples were contaminated with debris. Examiner agreement was found to be fair to moderate over the entire dataset. No participants reported practising the single-use of endodontic hand files. Great variation existed in the way that endodontic hand files were decontaminated. The primary reason provided by participants for the re-use of endodontic hand files was financial concerns regarding single-use protocols.
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    The effect of different polishing systems on the surface roughness of a nanocomposite and a microhybrid composite
    (University of Pretoria, 2015) Brandt, Paul Dieter; dorette.kritzinger@up.ac.za; Kritzinger, Dorette
    Objectives: To evaluate the surface roughness of a nanocomposite and a microhybrid composite after polishing the composites with different polishing systems. Key words: Polishing, surface roughness, microhybrid composite, nanocomposite, Sof-Lex XT, Spiral Wheels, Enhance, Intensiv UniglossCellbrush, Zircon-Brite, Dura-White stones, Mylar strips Methods: The composites used in this study were Filtek Supreme XTE (3M ESPE, St Paul, USA) and Z100 (3M ESPE, St Paul, USA). Thirty-five composite samples were made from each of the two composites. Uncured composite was placed into an aluminium ring mould, 10mm X 2mm. Both the upper and lower surfaces of the composite were covered with Mylar strips and glass plates, before the specimens were cured for 40 seconds from both sides. Samples were randomly divided into seven groups. The groups were: 1. Mylar polyester strip (control) 2. Sof-Lex XT finishing and polishing discs (3M ESPE, St Paul, USA) 3. Sof-Lex Spiral Wheels (3M ESPE, St Paul, USA) 4. Dura-White stones (Shofu Inc, Kyoto, Japan) 5. Intensiv UniglossCellbrush (Intensiv SA, Montagnola, Switzerland) 6. Enhance finishing and polishing system (Dentsply, Milford, USA) 7. Sof-Lex Spiral Wheels combined with Zircon-Brite (Dental Ventures of America, Corona, USA) The polishing of the specimens was performed by a single operator according to manufacturer s instructions. The mean surface roughness of each specimen was determined using a profilometer (Surftest SJ 210, Mitutoyo, Tokyo, Japan). Three readings were collected from each specimen. Data was statistically analysed using ANOVA. Scanning Electron Microscope (JEOL JSM-5800 LV, Tokyo, Japan) photos were taken of the representative samples. Results: Statistically significant differences in surface roughness were observed between the following groups: Z100 and Filtek Supreme XTE with the polishing systems combined (p=0.005); Control group vs all the polishing systems; Sof-Lex XT finishing and polishing discs vs Dura-White stones, Intensiv UniglossCellbrush, Enhance finishing and polishing system (p < 0.0001); Sof-Lex Spiral Wheels vs Dura-White stones, Intensiv Unigloss Cellbrush, Enhance finishing and polishing system (p <0.0001); Dura-White stones vs Intensiv UniglossCellbrush, Enhance finishing and polishing system, Sof-Lex Spiral Wheels/Zircon-Brite (p <0.0001); Intensiv UniglossCellbrush vs. Spiral Wheels/Zircon-Brite (p<0.0001); Enhance finishing and polishing system vs. Spiral Wheels/Zircon-Brite (p <0.0001). Conclusion: Filtek Supreme XTE displayed significantly better polishability and lower surface roughness values after polishing than Z100. The composite samples cured against the Mylar polyester strip produced significantly smoother surface roughness values than all the polishing systems tested in this study. The following polishing systems led to the smoothest surfaces after polishing: Sof-lex Spiral Wheels in combination with Zircon-Brite, as well as the Sof-Lex Spiral Wheels and Sof-Lex finishing and polishing discs. These systems were significantly smoother than the Enhance system used in combination with Prisma Gloss polishing paste, and also the one-step polishing system Intensiv UniglossCellbrush. There was no statistically significant difference between Sof-Lex Spiral Wheels in combination with Zircon-Brite, the Sof-Lex Spiral Wheels and the Sof-Lex finishing and polishing discs.
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    Fracture strength and fracture behaviour patterns of cusp-replacing fibre reinforced composite restorations.
    (University of Pretoria, 2015) Brandt, Paul Dieter; De Wet, Francois A.; landas@lando.co.za; Visser, Jacobus
    Objectives: This in vitro study investigated and compared the fracture strength and behaviour patterns of a conventional posterior composite resin, a composite resin reinforced with nano-scale electrospun glass-fibres and a conventional composite resin placed on a fibre substructure, all used in cusp-replacing posterior composite resin restorations. Methods: Seventy-five extracted, lower, left, first and second molars were prepared to accept standardized restorations replacing the mesio-lingual cusp. The specimens were randomly divided into 3 groups of 25 each: Group A (control) was restored with a conventional posterior composite resin, Group B was restored with the composite resin reinforced with nano-scale electrospun glass fibres and Group C was restored with a conventional posterior composite resin reinforced with a fibre substructure. All restored specimens were thermocycled for 500 cycles between 5° C and 55° C with a dwell time of 30 seconds, then imbedded in plastic cylinders in acrylic resin. The specimens were loaded at a 30° angle to the long axis of the tooth, using a jig mounted in a universal testing machine until fracture occurred. Fracture strength was recorded and specimens were then stained to highlight fracture patterns and subsequently studied under a microscope. Fractures were classified as restorable/non-restorable. Sub-classification included adhesive and cohesive failures. Results: Compared to Group A both techniques of fibre inclusion significantly strengthened the cusp-replacing composite restoration (ANOVA p = 0.05) Compared to Groups A and B the group of restorations placed on a fibre sub-structure (Group C) exhibited significantly more fractures that were classed as restorable. Compared to Group A and C the group restored with the composite resin reinforced with nano scale electrospun glass fibres (Group B) displayed significantly more fractures that were classed as non-restorable (Fisher s Exact Test p = 0.05). Conclusion: Both fibre inclusion techniques significantly strengthened cuspreplacing posterior composite restorations. Fracture behaviour patterns differed significantly between the two fibre-strengthening techniques.
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    Comparison of canal transportation and centering ability of K-files the ProGlider file and G-file : a micro-computed tomography study of curved canals
    (University of Pretoria, 2015) Van der Vyver, Petrus Jacobus; farzanapaleker@gmail.com; Paleker, Farzana
    The aim of this in vitro study was to investigate the canal centering ability and apical root canal transportation of pre-curved stainless steel K-files, the ProGlider file and GFiles after glide path enlargement in curved root canals of extracted human mandibular molars using micro-CT scanning. The working times for the different glide path enlargement methods were also recorded. Ninety untreated curved root canals from extracted molars were randomly divided into three groups (n = 30). Group 1: manual glide path preparation with size 0.10 Kfile and enlargement with size 0.15 and 0.20 hand K-files; Group 2: manual glide path preparation with size 0.10 K-file and enlargement with NiTi rotary G-Files; and Group 3: manual glide path preparation with size 0.10 K-file and enlargement with the NiTi rotary ProGlider file (ISO tip size 16). Micro-computed tomography was used to scan the teeth before and after glide path enlargement. Three-dimensional images were reconstructed from the pre- and post-instrumentation scans to enable a comparison of the centring ability at three selected levels: 1 mm from the apical foramen (D1), at the point of maximum root curvature (Dmc) and 7 mm from the apical foramen (D7). Canal transportation was assessed at 1 mm from the apical foramen in eight directions (MB, B, DB, D, DL, L, ML, M). The time it took to enlarge the glide paths for each group was also calculated. One-way Analysis of Variance was performed to assess if significant differences existed between the three groups for the variables being compared (p<0.05). A Bonferroni adjusted p value of 0.016 was used for pairwise comparisons of centring ability. K-files displayed statistically significantly higher centering ratios than G-Files at D1. At all levels the ProGlider file exhibited statistically significantly lower centering ratios than K-files. At Dmc, the ProGlider file demonstrated statistically significantly lower centering ratios than G-Files. Ratios were significantly similar between K-files and GFiles at D7 as well as between G-Files and the ProGlider file at D7 (p<0.016). Apical canal transportation for K-files was significantly more than G-Files in five directions and the ProGlider file in six directions (p<0.05). Glide path enlargement time for Kfiles was significantly slower (74.92 s ± 2.60 s) than G-Files (41.87 s ± 20.19 s) and the ProGlider file (27.95 s ± 8.55 s)(p<0.05). There was no statistically significant difference between glide path enlargement times of G-Files and the ProGlider file. Findings suggest that NiTi rotary glide path files are suitable for safe glide path enlargement because they cause less apical canal transportation than stainless steel hand K-files. Of the two NiTi rotary glide path file groups, the ProGlider file showed an overall significantly better centering ability around the entirety of the original canals, particularly at the point of maximum curvature. Glide path enlargement with the NiTi rotary glide path file groups was significantly faster than Kfiles (p<0.05).
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    An In Vitro comparison of three different techniques to create a glide path prior to nickel titanium rotary instrumentation
    (University of Pretoria, 2013) Van der Vyver, Petrus Jacobus; ijcassim@worldonline.co.za; Cassim, Imran
    The preparation of a glide path prior to the use of rotary nickel titanium instrumentation reduces torsional stress and the risk of rotary nickel titanium instrument separation. The objective of this in vitro study was to evaluate 3 different glide path preparation techniques in respect of:  Percentage change of curvature from original canal anatomy; and  The occurrence of aberrations in canal anatomy (ledging, zipping and elbows). One hundred and twenty S-shaped Endo-Training-Blocks were selected. The canals were injected with India ink dye. The blocks were indexed with 3 bur marks and placed into a template before pre-instrumentation images were acquired digitally. The blocks were randomly divided into four groups of thirty each. Glide paths were prepared by a single operator with stainless steel hand K-files only, up to ISO size 20 (group 1, control), stainless steel hand K-files in the M4 reciprocating hand-piece up to ISO size 20 (group 2), hand K-files to ISO size 10 then NiTi rotary PathFiles (group 3) and hand K-files to ISO size 10 then NiTi rotary X-Plorer files (group 4). After glide path preparation the blocks were replaced into the template and post-instrumentation images were digitally acquired. Percentage change of curvature from original canal anatomy: Pre-instrumentation and post-instrumentation images were imported into Rhinoceros software to determine the end points of the canal curves and calculate the percentage change of canal curvature for the radii of apical and coronal curves. The data was collected and tabulated. Differences in canal curvature modification were statistically analysed with respect to logarithmic transformed change from baseline using ANCOVA (p<0.001) with logarithmic transformed pre-instrumentation values as covariate. After establishing preparation differences, both for change from baseline (pre-instrumentation) for apical and coronal curves, specific differences were tested using Fisher’s LSD for pairwise comparisons. Prepared groups differed significantly (p<0.001) and in particular, group 1 (Hand K-files) (control) and group 2 xiii (Hand K-files in M4 Safety reciprocating hand piece) differed significantly from all the other groups while group 3 (Hand K-files and PathFiles) and group 4 (Hand K-files and X-Plorer files) did not differ significantly. Group 3 (Hand K-files and PathFiles) and group4 (Hand K-files and X-Plorer files) were also superior to group1 (Hand K-files) (control) and group2 (Hand K-files in M4 Safety reciprocating hand piece). The occurrence of aberrations in canal anatomy (ledging, zipping and elbows): Pre-instrumentation and post-instrumentation images were superimposed using Adobe Photoshop software. The images were imported into a PowerPoint presentation and examined by three different blinded clinicians independently, for the presence of aberrations. There were no differences between the examiners in their assessment of the images. The data was collected and tabulated. The incidence of canal aberrations was analysed using Fisher’s exact test (p<0.05). The groups differed significantly regarding the number of aberrations (p=0.005). In particular, group 1 (control) (Hand K-files) and group 2 (Hand K-files in the M4 reciprocating hand piece) did not differ statistically (p=0.254; 20% and 6.67%). However group 2 (hand K-files in the M4 reciprocating hand piece) also did not differ significantly from group 3 (Hand K-files and PathFiles) and Group 4 (Hand K-files and X-Plorer files) (p=0.326). There were no aberrations detected in the rotary NiTi groups (group 3 and group 4).
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    The influence of glide path preparation on the failure rate of nickel-titanium reciprocating instruments
    (University of Pretoria, 2013) Van der Vyver, Petrus Jacobus; casper.jonker@up.ac.za; Jonker, Casper Hendrik
    Introduction: The aim of this in vitro study was to determine the influence of two glide path preparation methods on the fracture rate of the Primary 25/08 WaveOne reciprocating instrument. The number of simulator Endo-Training-Blocks in each group were calculated at the time of instrument fracture and compared to determine the influence of glide path preparation on the failure rate of the Primary 25/08 WaveOne reciprocating instrument. Preparation times for different glide path methods and total time for root canal preparation, with or without glide path, was also calculated. Materials and Methods: Simulator Endo-Training-Blocks (n = 300) were selected and randomly divided into 3 groups (n = 100). The 3 groups were then sub-divided into 5 smaller groups (n = 20). Root canal preparation was done with new primary 25/08 WaveOne instruments allocated to each group (5 in total for each group, 1 for each sub-group) following different methods for glide path preparation. Group 1: no glide path (control); Group 2: glide path preparation with stainless-steel hand files (size 10 K-File followed by size 15 K-File and finally size 20 K-File until loose fitting); and Group 3: glide path preparation with rotary PathFiles (size 10 K-File until loose fitting followed by PathFile no.1 (ISO 13 tip), PathFile no.2 (ISO 16 tip) and finally PathFile no. 3 (ISO 19 tip)). The Primary 25/08 WaveOne reciprocating instrument was used with the WaveOne endodontic motor in “WaveOne All “mode with a brushing motion on the outstroke. Simulated root canals were irrigated with sterile water and Glyde was used as lubricating agent. The outcome was measured by recording how many simulators could be prepared with one instrument before instrument breakage occurred. The preparation protocol was repeated 5 times. The time it took to prepare the glide path and the total preparation time was also calculated. The data of the different parts of the project were collected and statistically analysed using the ANOVA / Bonferroni test. Results: Glide path preparation with PathFiles was significantly faster (13.3 s ± 2.60 s) than with hand files (25.1 s ± 1.70 s) (P < 0.001). The highest number of simulators could be prepared after glide path preparation was performed with PathFiles (19.2 ± 0.84) (P < 0.001). Pairwise comparisons at the Bonferroni adjusted significance level of 0.017 demonstrated that there were statistical significant differences (P < 0.001) when PathFiles (19.2 ± 0.84) and hand files (17.6 ±1.14) were compared to the no glide path group (7.4 ± 0.89). There was no statistical significant difference between PathFiles and hand files groups. Total Preparation time was significantly shorter (P < 0.001) when an initial glide path was prepared with PathFiles (12.7 ± 0.22 s). The longest preparation time (P < 0.001) was calculated in group 1 where no glide path (21.2 ± 0.20 s) was present and the Endo-Training-Blocks were left undisturbed. Conclusion: Initial glide path preparation with PathFiles resulted in shorter preparation time (glide path and total preparation) and allowed a higher number of simulators prepared before failure of the WaveOne instrument.
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    In vitro Infection and Disinfection of Dentinal Tubules in Human Teeth
    (University of Pretoria, 2013) Botha, Francien Susanna; Van der Vyver, Petrus Jacobus; nichola.warren@up.ac.za; Warren, Nichola
    Introduction: Bacteria are the most common pathogens responsible for pulpal necrosis and periapical disease conditions. The importance of eradicating bacteria and their endotoxic by-products has been highlighted in numerous studies. Aim: The aim of this in vitro study was to establish the efficacy of six endodontic disinfection protocols in eradicating Enterococcus faecalis from single root canals of human teeth. Materials and Methods: Endodontic access cavities were prepared on 86, extracted, single rooted, human teeth. Root canal preparation was done using nickel titanium rotary files. Each tooth was sterilised, inoculated with E. faecalis and randomly allocated to one of seven groups (n = 12). The six disinfection protocols were 3% sodium hypochlorite solution (NaOCl), 2% chlorhexidine digluconate solution (CHX), Chlor-XTRA, 3% NaOCl combined with 2% CHX, 3% NaOCl followed by photo-activated disinfection (PAD) and PAD alone. The seventh group was irrigated with sterile water (control). The roots were fractured longitudinally. Dentine samples from coronal, middle and apical sections of one half of each root were plated onto brain heart infusion (BHI) plates. These were incubated anaerobically at 37⁰C for five days. The colony-forming units (cfu) were counted. The second half of each root was prepared for Scanning Electron Microscopy. The Pairwise Wilcoxon Rank Sum test and the Kruskal-Wallis test were used to compare the cfu counts of the seven groups to one another. Results: Two per cent CHX, Chlor-XTRA, combination of 3% NaOCl and 2% CHX and irrigation with 3% NaOCl followed by PAD were able to eradicate E. faecalis from the coronal levels of the root canals. A combination of 3% NaOCl and 2% CHX and irrigation with 3% NaOCl followed by PAD were able to eradicate E. faecalis from the middle levels of the root canals. None of the disinfection protocols were able to eradicate E. faecalis from the apical levels of all root canals. The regimen of 3% NaOCl followed by 2% CHX was slightly more efficient in eradicating E. faecalis from the root canals than the other disinfection regimens. Dentine erosion and precipitate formation were two incidental observations in some of the samples upon SEM examination.
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    Shear bond strength, microleakage and anti-bacterial properties of self-etching bonding systems
    (University of Pretoria, 2010-03-01) De Wet, Francois A.; pbrandt@medic.up.ac.za; Brandt, Paul Dieter
    Self-etching dentine bonding agents are a recent addition to the choice of bonding agents which a clinician has available to bond resin restorations to tooth structure. The so-called ‘traditional’, total-etch fourth and fifth generation dentine bonding agents have proven their clinical abilities and the question now remains whether these ‘new’ self-etching dentine bonding agents will clinically perform as well as the ‘proven’ total-etch dentine bonding agents. For the purpose of this dissertation the author completed three research projects which were performed to evaluate the efficacy of a selection of dentine bonding agents and then used the results to compare some properties (shear bond strength, microleakage, and anti-bacterial properties) of total-etch dentine bonding agents with some self-etching dentine bonding agents. All discussions will focus on the three dentine bonding agent properties evaluated by the three research projects performed. The three specific aims of this study were:
    • To compare the dentine shear bond strength of a selection of self-etching dentine bonding agents with that of a total-etch dentine bonding agent control.
    • To compare dentine and enamel microleakage values of a selection of self-etching bonding agents with that of a total-etch dentine bonding agent control.
    • To evaluate the possible anti-bacterial properties of a selection of dentine bonding agents, with focus placed on the self-etching dentine bonding agent ABFb (Clearfil Protect Bond).
    The studies performed by the author achieved comparative/similar results to some studies described in the literature but it is clear from the literature that some studies provide conflicting results, especially leakage of enamel margins when using self-etching bonding agents. Taking into consideration the limitations of the three studies performed, it can be concluded that as far as the three evaluated properties of self-etching dentine bonding agents are concerned, they should prove to be acceptable clinical alternatives for use in place of total-etch dentine bonding agents. Copyright
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    Microleakage and marginal adaptation of ultrasonically cured glass-ionomer sandwich restorations
    (University of Pretoria, 2008) Dannheimer, M.; jeanine.fourie@up.ac.za; Fourie, Jeanine
    Resin based composite is currently one of the most popular dental restoratives. Used as a direct restorative material, it displays many beneficial properties such as excellent micromechanical bonding to enamel, polishability and aesthetics. Despite many advances in dentine bonding agents, dentine bonding remains problematic with microleakage and recurrent caries, being frequent clinical sequelae. The open sandwich technique was developed to overcome two problems: deficient bonding of resin composites to dentine, and inadequate strength and fracture toughness of conventional glass-ionomers (GI). GI displayed excellent cavity sealing abilities by virtue of their chemical adhesion to tooth structure. Resin-modified glass-ionomers (RMGI) were developed to improve on the weaknesses of conventional GI during early setting i.e. setting rate, water sensitivity and strength. Recently literature has reported the use of ultrasonic activation to set conventional GI, opening the possibility of improving the initial properties of the material and suitability for use in the open sandwich technique. The aim of this study was to compare microleakage of Ketac Molar, Ketac Molar set by ultrasound (US), Vitremer and Ketac N100 used in the open sandwich technique, with the control of a resin based composite, Filtek Z250. Two hundred Class II cavities were prepared in a hundred caries free, human, molar teeth, with half of the cervical margins placed apical and the rest coronal to the cemento-enamel junction. For each material, twenty restorations were placed for each cervical position. The sandwich materials were placed to fill the interproximal box level with the pulpal floor, and a final two layers of resin composite was then placed to complete the restoration. Restored teeth were stored in a laboratory oven for 7 days at 37 °C; margins were then finished initially with a medium grit Sof-Lex disc and finally with a fine diamond drill. Material groups were separated into two halfs to commence microleakage testing or thermocycling. Thermocycling was conducted for 500 cycles between 5 °C and 55 °C, with a dwell time of 30 seconds. Restored teeth were then covered with nail varnish around the restoration margins, and immersed in 0.5% basic fuchsin solution for 24 hours. They were then cleaned, embedded in clear self-curing acrylic and sectioned 3 times with an Accutom-2 precision saw, at 2 mm intervals. Sections were evaluated using a light microscope under 4 time’s magnification and microleakage scores given as: 0 = no leakage; 1 = < ½; 2 = > ½ distance to the axial wall/pulpal floor; 3 = leakage up to axial wall/pulpal floor. Statistical analysis was undertaken using Analysis of Variance (ANOVA) for the cervical and occlusal microleakage scores; p-values <0.05 were considered significant. The cervical microleakage results of cavity margins in dentine showed that Ketac Molar (US) performed better than Ketac Molar, and Ketac N100 performed better than Vitremer. Results in enamel showed no significant differences. The use of the open sandwich technique effectively reduced microleakage of cervical cavity margins placed in dentine but failed to reduce occlusal microleakage of Filtek Z250. Copyright
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    In vitro evaluation of root canals obturated with four different techniques
    (University of Pretoria, 2009) Van der Vyver, Petrus Jacobus; Botha, Francien Susanna; evdm@lantic.net; Van der Merwe, Carel
    After cleaning and shaping of the root canal the final objective of the endodontic procedure is to obtain a three-dimensional obturation of the root canal space with a fluid-tight seal at the apical foramen. The objective of this in vitro study was to evaluate four different obturation techniques in respect of: • the radiographic quality of root canal obturation, • apical leakage and • the potential of these techniques to obdurate lateral canals One hundred and sixty canals were prepared by using RaCe nickel titanium rotary files to a size 30 with 6% taper. During preparation irrigation was done with TopClear Solution (17% EDTA and 0.2% cetremide) and ChlorXTRA (6% sodium hypochlorite). The canals were divided in four groups of forty canals each and were obturated using the Hybrid Root SEAL technique, the EndoREZ technique, the System B/Obtura technique and the Thermafil technique. The Radiographic Quality of Root Canal Obturation: Digital radiographs were taken of the four groups of obturated canals from a buccolingual and a mesiodistal direction. The quality of obturation was determined for the coronal and apical halves of each canal and scored according to radiographic appearances. The data was tabulated and statistically analyzed using the Mann- Whitney U test. The Hybrid Root SEAL technique demonstrated a statistically significant higher number of radiographic defects in the coronal aspects of the root canals when compared to the System B/Obtura and Thermafil techniques (p<0.05). There was no statistically significant difference between the radiographic defects in the coronal aspects of the root canals between Hybrid Root SEAL and EndoREZ techniques (p>0.05). The Hybrid Root SEAL technique demonstrated a statistically significantly higher number of radiographic defects in the apical aspects of the root canals compared to all the other groups (p<0.05). Apical Leakage: Twenty obturated canals of each of the four groups were processed for evaluation of apical leakage. The root surfaces were coated with nail varnish and sticky wax, leaving 4.0 mm around the apical foramen exposed. Specimens were immersed in 2% methylene blue dye for 48 hours, rinsed in distilled water and embedded in clear acrylic resin. Specimens were sectioned horizontally in 1 mm increments and the extent of dye penetration was measured to the nearest millimeter using a stereomicroscope. The data was tabulated and statistically analyzed using the Man-Whitney U test. The specimens that were obturated with the EndoREZ technique demonstrated the least apical leakage compared to all the other groups tested in this study. However, there was only a statistically significant difference when the EndoREZ technique was compared to the Hybrid Root SEAL and System B/Obtura techniques (p<0.05). The specimens that were obturated with the System B/Obtura technique demonstrated the most apical leakage compared to all the other groups tested in this study. However, there was only a statistically significant difference when the System B/Obtura technique was compared to the EndoREZ and Thermafil techniques (p<0.05). The Potential to Seal Lateral Canals: Twenty obturated canals of each of the four groups were processed for evaluation of the potential to seal lateral canals. The specimens were subjected to a clearing technique and a morphological analysis was performed using a stereomicroscope. Lateral canals were counted and graded within the coronal, middle and apical thirds of the roots. The data was tabulated and statistically analyzed using the Man-Whitney U test. The Thermafil technique demonstrated the greatest number of filled lateral canals. However, there was no statistically significant difference between the Thermafil technique and all the other techniques (p<0.05).