Research Outputs (Oral Health Sciences)

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Author: search.filters.author.Grossman, E. S.Start date: 2003

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    How well do fourth year Wits Dental Students place resin composite restorations?
    (2003) Lightfoot, J.; Clarke, F. M.; Grossman, E. S.
    OBJECTIVES:To evaluate, by means of a scanning electron microscope (SEM) the quality of resin composite restorations, placed as a first attempt by fourth-year dental students. METHODS: Ten Class IV direct composite restorations, placed in plaster-mounted extracted incisor teeth as part of pre-clinical course requirements, were selected. Specimens were evaluated and graded on a two-point scale by a staff member according to departmental clinical evaluation criteria. Five restored teeth were prepared for surface evaluation of marginal integrity, surface roughness and contour using SEM. The remaining specimens were embedded in resin and ground down transversely, parallel to the incisal edge until a dentine core was apparent. The ground surfaces were polished, prepared for SEM and assessed for etched layer, placement of bonding agent, composite adaptation and overall consistency. RESULTS: Clinical assessment and SEM surface evaluation correlated favourably for all criteria, except contour, indicating that students were reasonably competent in finishing techniques. Ground samples revealed acceptable etched enamel layers and marginal adaptation. Bonding agent thickness varied between 0 and 200 microns casting doubt on procedural accuracy. Porosities and voids were apparent within the resin composite. Internal features were the main reason for unsatisfactory grades. CONCLUSIONS: Students placed restoration satisfactorily. They would benefit if able to examine sectioned restorations to understand critical placement techniques which would contribute to resin composite restoration success. A research component can be introduced into the dental undergraduate curriculum by way of similar projects linked to didactic course-work.
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    Surface roughness values for resin based materials
    (2004) Grossman, E. S.; Rosen, M; Cleaton-Jones, P.E; et al
    INTRODUCTION: Surface roughness of dental restorative materials is most often established with the Ra value obtained using profilometry or by assessing surface topography with the scanning electron microscope (SEM). Both methods should validate each other in confirming surface roughness. AIMS AND OBJECTIVES: The purpose of this study was to compare surface roughness values obtained with a profilometer to the SEM appearance of 6 resin-based restorative materials and assess whether Ra was appropriate as a sole surface roughness measure. Methods Six 5mm diameter specimen discs of Prodigy (Pr); Z100 (Z); Compoglass F (C); Hytac Aplitip (H); Photac-Fil (Pf) and Vitremer (V) were prepared against Mylar strips and stored in distilled water for 14 days. One side of each disc was sequentially polished with Soflex discs to super fine state, the other side remained unpolished. Three surface roughness measurements were made on each surface (n=18) recording Ra, Rv, Rp and Rt values, this data was subjected to a four way ANOVA and Tukey's Studentised Range Test (p=0.05). Two unpolished and two polished discs per material were prepared for SEM, evaluated and visually grouped for surface roughness. RESULTS: Approximate ascending order of roughness was Z, Pr, H, C, V, Pf for Ra, Rv, Rp and Rt and un/polished treatment. Polishing increases surimens into a "bland" (Pr, H, Z, C) and "textured" group (Pf and V). The polished specimens gave four groups: (Pr), (Z and C), (H) and (V and Pf) of increasing surface complexity. Polishing caused surface scratching, removed the matrix, reduced or removed filler particles and exposed voids within the material. CONCLUSIONS: This study emphasises the importance of using more than one technique to assess surface roughness. Rv and Rp values should be utilised to better understand polish induced surface feature changes. Rv maximum is a better measure to identify surface defects which could affect restoration longevity.
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    Spreadability of two glass ionomer cements used in Atraumatic Restorative Treatment (ART)
    (2004) Sindhu, R.; Grossman, E. S.
    'Press finger' in atraumatic restorative treatment (ART) is used to spread a glass ionomer cement (GIC) to seal the restoration margin and adjacent pits and fissures. This study compared the spreadability of Fuji IX and Ketac-Molar to establish which was best suited for this purpose. Twenty equally spaced cavities (35 mm apart) were machine-cut in each of two Perspex slabs 200 x 100 x 20 mm. Each cavity was 3 mm deep with a 4 mm diameter. Two V-shaped grooves 1 mm deep were cut to traverse the cavities: one 0.5 mm wide, the other 0.25 mm wide. Equal amounts (0.25 ml) of GIC were dispensed, 20 cavities for Fuji IX and 20 for Ketac-Molar and condensed under light finger pressure using a 20 mm diameter cork thinly coated with petroleum jelly. This allowed the GIC to be condensed into the cavity and spread into the differently sized grooves. The samples were stored in deionised water for 24 hours whereafter the length to which the GIC had spread along each groove from the cavity edge was measured to the closest 0.01 mm. The data were analysed using ANOVA and the unpaired Student's t-test (P < 0.05). There was a statistically significant difference between the length of spread of the two GICs (t = 2.534; P = 0.013) which was confined to the 0.25 mm width groove (t = 2.83; P = 0.007) with Fuji IX spreading much further along the groove (10.25 +/- 1.17 mm) than Ketac-Molar (7.66 +/- 4.21 mm). Fuji IX appears to be the better sealant material when selecting for spreadability in ART.