School of Oral Health Sciences

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Start date: 2001End date: 2009

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    Zinc oxide-eugenol and calcium hydroxide pulpectomies in baboon primary molars: histological responses
    (2004) Cleaton-Jones, P.; Duggal, M.; Parak, R.; et al
    AIM: To compare histological responses to zinc oxide-eugenol (ZOE) and calcium hydroxide (CH) pulpectomies in primary molar teeth with inflamed pulps. STUDY DESIGN:This was an experimental study in 17 juvenile baboons (Papio ursinus). METHODS: Pulpitis was induced with fresh human carious dentine or Streptococcus mutans placed into occlusal cavities in 78 primary molars; after 14 days a pulpectomy was performed on the same primary molars with the two root fillings randomly allocated. The root canal openings were then covered with IRM and the cavity filled with amalgam. After 90 days specimens were harvested and examined under the light microscope with the examiner blind to the treatment. RESULTS:Reaction frequencies in the ZOE-treated versus CH-treated teeth were: no recognisable pulp 89% and 82%, internal root resorption 0% and 1%, external root resorption 11% and 24%, presence of bacteria 5% and 18%, periapical abscesses 24% and 52%. STATISTICS:Fisher's exact probability test showed a statistically significant higher prevalence of periapical abscesses in the CH-treated group (P=0.03, relative risk 2.2). CONCLUSIONS: ZOE pulpectomy is preferred to CH for the treatment of infected pulps in primary molars
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    Ferric sulphate and formocresol pulpotomies in baboon primary molars: histological responses
    (2002) Cleaton-Jones, P.; Duggal, M.; Parak, R.; Et al
    Aim: To compare pulpal reactions to ferric sulphate and formocresol pulpotomies in primary molar teeth with inflamed pulps. Study design: An experimental study in 15 juvenile baboons (Papio ursinus). Materials and methods: Pulpitis was induced with fresh human carious dentine or Streptococcus mutans placed into occlusal cavities in 57 primary molars; after 14 days a pulpotomy was performed on the same primary molars with the two pulp medicaments randomly allocated; the pulp was covered with IRM and the cavity filled with amalgam. After 90 days specimens were harvested and examined under the light microscope with the examiner blind to the treatment. Results: Reaction frequencies in the ferric sulphate-treated and formocresol-treated teeth were: recognisable pulp 52% and 50%, dentine bridges 16% and 12%, internal root resorption 12% and 4%, external resorption 28% and 31%, bacteria 12% and 23%, peri-apical abscesses 32% and 38%. Statistics: Fisher’s exact probability test showed no statistically significant differences between reaction frequencies in the two treatment groups. Conclusion: A pulpotomy in a primary tooth may be clinically successful in the presence of adverse histological reactions.
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    Airway status in civilian maxillofacial gunshot injuries in Johannesburg, South Africa
    (2002) Tsakiris, P.; Cleaton-Jones, P. E.; Lownie, M. A.
    BACKGROUND: Airway management of the maxillofacial gunshot injury constitutes a critical decision and an area that requires review in the context of civilian injuries. Most of our knowledge is extrapolated from military experience, which constitutes a different trauma patient group. This paper reports a retrospective survey of airway status in relation to maxillofacial gunshot injuries. The objective is to correlate clinical findings with treatment decisions. METHODS: A survey was done of 11,622 archived maxillofacial surgery records (1987-1992) in the three academic hospitals in Johannesburg. RESULTS: There were 211 maxillofacial gunshot injuries, for which 92 patient records had sufficient detail for inclusion in the analysis. The typical patient was a black male aged 20-29 years, shot with a low-velocity bullet of 0.38 calibre, admitted to hospital the day of the injury, operated on within 4 days, and discharged 4 days later. The airway was threatened in 20/92 cases at admission; 12/20 cases were treated with oro-or nasotracheal intubation, and 9/12 later had elective tracheostomies; 8/20 needed immediate surgical airways, 5 tracheostomies and 3 cricothyroldotomies (all later converted to tracheostomies). Three of thirty-seven patients with normal airways on admission later required emergency tracheostomy. CONCLUSIONS: An abnormal airway was significantly more likely after a high-velocity injury, and when the tongue, floor of mouth, midline or bilateral facial skeletal bones were involved.
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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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    Clinical, histological and microbiological study of hand-excavated carious dentine in extracted permanent teeth
    (2003) Bönecker, M.; Grossman, E.; Cleaton-Jones, P. E.; et al
    Changes in cultivable flora in dentine samples collected before and after hand excavation were examined in association with clinical status of the cavity surface, light microscopy and scanning electron microscopy (SEM). Thirty-five extracted permanent molar teeth with an occlusal caries lesion were excavated with hand instruments according to the atraumatic restorative treatment (ART) approach. Excavation pressure, dentine colour and consistency were recorded at the dentine-enamel junction (DEJ) prior to carious dentine removal and at the cavity floor after the final excavation; a microbiological sample of dentine was taken at both stages. Twelve restored teeth; six with positive and six with negative bacterial growth on the second sample, were selected for light microscopy and SEM. The hand-excavation removed tooth structure was soft, irreversibly damaged, dark and highly infected. Hand excavation reached dentine of increased hardness with a more normal colour to provide a sound structural base for restoration. Light and SEM examination of the cavity floor showed infected dentinal tubules in all 12 teeth examined. Linear logistic analysis showed a statistical association between light-yellow dentine on the cavity floor and an absence of bacterial growth (P = 0.006). This short-term in vitro study showed that caries-producing bacteria remained in dentine close to the cavity floor in 26/35 teeth despite clinical observations that indicated a suitably prepared cavity floor.
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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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    Long in the tooth
    (2002) Volchansky, A.
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    To splint or not to splint, that is the question
    (2001) Volchansky, A.; Gavron, G.
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