School of Oral Health Sciences
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Item 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.Item 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.Item Surface roughness of aesthetic restorative materials: an in vitro comparison(2001) Rosen, M.; Grossman, E. S.; Cleaton-Jones, P. E.The purpose of this study was to compare the surface roughness of three types of aesthetic restorative material. Six standard samples of two brands of each type of material were prepared namely: hybrid composites (Prodigy, Z100), compomers (Compoglass F, Hytac Aplitip) and glass ionomer cements (Photac-Fil, Vitremer) in a perspex mould (N = 36). Upper and lower surfaces were covered with Mylar strips which, in turn, were covered with glass slides and compressed to express excess material. After light curing, specimens were stored in distilled water for 14 days. Thereafter, one side of each specimen was polished sequentially with medium, fine and super fine Soflex discs (treatment). Untreated surfaces served as controls. All surfaces were examined with Talysurf and the surface roughness (Ra) of each specimen was recorded. Three measurements were made of each specimen. A 4-way ANOVA and Tukey's Studentised range test were used to analyse the data. Statistically significant effects were found for both type of material (P = 0.0001) and for treatment process (P = 0.0065). Among unpolished specimens: Compoglass F is significantly rougher than Vitremer, Z100, Prodigy and Hytac Aplitip, and compomers are significantly rougher than hybrids. Among polished specimens: Photac-Fil is significantly rougher than Z100 but does not differ from Compoglass F, Vitremer, Prodigy and Hytac Aplitip, and glass ionomers are also significantly rougher than hybrids. The smoothest surface is obtained when curing materials against a Mylar strip.Item Microscope observations of ART excavated cavities and restorations(2002) Grossman, E. S.; Mickenautsch, S.This in vitro light and scanning electron microscope study examined 39 extracted tooth specimens, hand excavated and restored according to atraumatic restorative treatment (ART), using 'press finger', by 'skilled' and 'novice' operators. Surface features of five excavated cavities, 12 restoration surfaces and the tooth restoration relationships of 22 bisected restored tooth crowns were examined to better understand the clinical effect of the technique. Hand-excavated cavity surfaces were rough with a complex surface arrangement of grooves, crevices, ridges, furrows and overhangs. Enamel and dentine were covered with debris except where surface fractures exposed enamel prisms and occluded dentinal tubules. Ten of the 22 bisected restored specimens had large voids (1-3 mm in length) within the glass-ionomer cement (GIC) restoration or at the tooth-restoration interface. Smaller bubbles (< 50 microns) and irregular shaped inclusions were common in all restorations. Adaptation of the GIC to the cavity margin was extremely variable and easily distinguished from the effects of dehydration shrinkage. It is thought that cavity surface irregularities could cause placement problems making it difficult to adapt the GIC to cavity peripheries. While 'press finger' enabled excellent penetration of GIC into fissures, the technique left restoration surfaces rough. At low magnification, surfaces were irregular; at magnifications higher than X500 scratches, pits, porosities, chipping and voids were evident. However, the 'press finger' technique was able to merge the GIC to a fine edge on the occlusal surface so that the restoration margin was not obvious. No apparent difference was found between the restorations placed by the 'skilled' and 'novice' operators. Tooth-restoration relationships in the ART approach are entirely different to those of traditional restorative techniques. The ART approach requires skill, diligence and comprehension to be undertaken correctly.