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Title: Calcium silicate cements used as a therapeutic dentine replacement : in-vitro and in-vivo studies
Author: Hashem, Danya Faisal
ISNI:       0000 0004 5368 4610
Awarding Body: King's College London
Current Institution: King's College London (University of London)
Date of Award: 2015
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Objectives: This research aims to investigate clinically and radiographically the dentine-pulp response to a calcium silicate cement (Biodentine™) compared to a glass ionomer cement (Fuji IX™ GIC) control material following indirect pulp capping in patients with signs of reversible pulpitis and to assess the integrity of the overlying resin composite restoration (N’Durance®) using USPHS and FDI criteria. This research also aims to evaluate the interface between Biodentine™ and the resin composite restoration using micro-shear mechanical testing and to investigate the possibility of reducing the radiation dose of cone beam computed tomography (CBCT) while maintaining an optimised image. Materials and methods: The randomised controlled clinical trial involved recruiting patients with signs of reversible pulpitis from Kings College Dental Institute at Guys Hospital. A CBCT and periapical radiograph (PA) were taken at baseline followed by minimally invasive (MI) treatment of the carious lesion. The definitive veneering composite restoration was placed one month later. The patients were followed up longitudinally at 6 and 12 months. Another CBCT and PA radiograph were taken at 12 months. The in-vitro study involves micro-shear testing of the bond strengths of resin composite to Biodentine™ vs. glass ionomer cement vs. resin modified glass ionomer cement using an adhesive in self-etch (SE) / total etch (TE) mode after aging the 3 substrates and the bond. Failure modes were characterised and SEM images were analysed. Reducing the CBCT radiation dose was attempted by comparing CBCT scans taken at 360° vs.180° rotation while maintaining accurate linear measurements. Accuracy of measurement was judged against the corresponding measurements taken from the porcine jaw specimens used as a reference standard. Results: 72 restorations (36 Biodentine™, 36 Fuji IX™) were placed randomly in 53 patients. Clinical success rates for Biodentine™ and Fuji IX™ GIC when used as indirect pulp capping agents were equal (83.3%). CBCT was significantly more effective in detecting periapical radiolucencies compared to PA radiographs (p < 0.05). The majority of healed CBCT lesions had received Biodentine™ while the majority that didn’t heal received Fuji IX™. With regards to the in-vitro studies, no significant differences were observed between (SE) / (TE) bonding modes (P=0.42). With material aging, a significant reduction in micro-shear bond strength occurred between early and delayed time intervals for Biodentine™ (P=0.001). Failure modes were primarily cohesive within the material (68.82%). Furthermore, no significant difference between the measurements from 180° or 360° rotations, nor any difference between the two rotations and porcine jaw specimens. Conclusions: Although no statistically significant difference was detected in the clinical efficacy of Biodentine™ / Fuji IX™ when used as therapeutic indirect pulp capping materials in patients with reversible pulpitis, CBCT showed a significant difference where the majority of healed CBCT lesions had received Biodentine™ while the majority that didn’t heal received Fuji IX™. The restorations performed well when assessed using USPHS and FDI criteria. Biodentine™ was found to be weak in its early setting phase. Placing the overlying resin composite is best delayed for at least 2 weeks to allow adequate setting/maturation of the Biodentine™ to withstand sufficiently the contraction forces of the resin composite. This would also allow sufficient time to review the tooth if Biodentine™ was placed on symptomatic pulps. A total etch or self-etch adhesive may be used. Moreover, a CBCT image sufficient to make accurate clinical measurements with a reduced radiation exposure may be obtained by using 180° rotation of the CBCT tube head.
Supervisor: Banerjee, Avijit ; Watson, Timothy F. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available