PubMed · 15612349
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
Adrian Becker. 2004. An interview with Adrian Becker.. https://pubmed.ncbi.nlm.nih.gov/15612349/
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
OBJECTIVES: To investigate the effect of polymerisation shrinkage strain of four posterior filling materials on cuspal movement, degree of conversion (DC) and cervical gingival microleakage of mesio-occlusal-distal (MOD) restorations placed incrementally in maxillary premolar teeth using a 'soft-start' polymerisation protocol. METHODS: Forty sound extracted upper premolar teeth were subjected to standardised preparation of a large MOD cavity before restoration. A 'soft-start' polymerisation curing regimen was used and each posterior filling material was placed in eight increments with the appropriate bonding system. A twin channel deflection measuring gauge allowed a measurement of individual cusp deflections at each stage of polymerisation. Restored teeth were thermocycled before immersion in a 0.2% basic fuchsin dye for 24h. After sagittal sectioning of the restored teeth in a mesio-distal plane, the sectioned restorations were examined to assess cervical microleakage. The DC was also assessed using a diffuse-reflectance accessory on a Fourier transform infra-red spectrophotometer. RESULTS: A significant increase in cuspal movement recorded for Z100 (20.06+/-4.71) compared with Filtek Z250 (16.52+/-3.26), P60 (14.23+/-3.71) and Admira (11.11+/-2.47). No significant reduction in cuspal movement was identified when compared with a previous study [6] where a full-intensity standard polymerisation protocol was employed. No significant differences were also identified between the materials when the cervical gingival microleakage scores or DC were examined for the 'soft-start' compared with the standard polymerisation protocol. CONCLUSIONS: Although material type remained a significant factor, the use of a 'soft-start' polymerization compared with a standard curing regime did not offer any significant reduction in associated cuspal movement, DC or gingival microleakage at the cervical dentine cavosurface margin of the cavities restored with the resin-based filling materials.
OBJECTIVES: To investigate the polymerisation shrinkage strain, associated cuspal movement, degree of conversion (DC) and cervical gingival microleakage of mesio-occlusal-distal (MOD) cavities restored with four resin-based composite (RBC) filling materials placed incrementally using a light emitting diode (LED) light curing unit (LCU). METHODS: Standardised extensive MOD cavity preparations on extracted teeth were performed on 40 sound upper premolar teeth. Restoration of the teeth involved the placement of RBCs in eight increments with the appropriate bonding system before irradiation using an LED LCU. Buccal and palatal cusp deflections at each stage of polymerisation were recorded using a twin channel deflection measuring gauge. Following restoration, the teeth were thermocycled, immersed in a 0.2% basic fuchsin dye for 24 h, sagittally sectioned and examined for cervical microleakage. The DC was determined using a Fourier transform infra-red (FT-IR) spectrometer. RESULTS: No significantly difference (P=0.677) in cuspal movement was recorded for Z100 (13.1+/-3.2 microm) compared with Filtek Z250 (8.4+/-3.5 microm), P60 (7.3+/-3.8 microm) and Admira (6.7+/-2.7 microm). The LED LCU deflections were compared with a halogen LCU used in a conventional (Fleming GJP, Hall D, Shorthall ACC, Burke FJT. Cuspal movement and microleakage in premolar teeth restored with posterior filling materials of varying reported volumetric shrinkage values. Journal of Dentistry, 2005;33:139-146) and soft-start mode (Fleming GJP, Cara RR, Palin WM, Burke FJT. Cuspal movement and microleakage in premolar teeth restored with posterior filling materials cured using 'soft-start' polymerization. Dental Materials, 2006, , in press) and a significant reduction in cuspal movement was identified for curing type and material type (P<0.001 and P=0.002, respectively). No significant differences were noted between the four RBC materials investigated when the DC or microleakage scores were examined for the LED LCU. SIGNIFICANCE: It would appear that irradiation of RBCs using the LED LCU offered a significant reduction in associated cuspal movement in large MOD cavities. However, the microleakage scores following polymerisation were significantly increased with dye penetration into the pulp chamber from the axial wall evident in teeth restored with the LED LCU.
OBJECTIVES: The aims of this investigation were to clarify the effects of 24h water-storage and finishing time on mechanical properties and marginal adaptation to a Class V cavity of eight modern flowable resin-composites. METHODS: Eight flowable composites, plus two controls (one microfilled and one hybrid composite), were investigated with specimen sub-groups (n = 10) for each property measured. The principal series of experiments was conducted in model Class V cavities with interfacial polishing either immediately (3 min) after setting or after 24 h water-storage. After the finishing procedure, each tooth was sectioned in a buccolingual direction through the center of the restoration, and the presence or absence of marginal-gaps was measured (and then summed for each cavity) at 14 points (each 0.5 mm apart) along the cavity restoration interface (n = 10 per group; total points measured = 140). The shear bond-strengths to enamel and to dentin, and flexural strengths and moduli data were also measured at 3 min and after 24 h water-storage. RESULTS: For all flowable composites, polished immediately after setting, 14-30 summed gaps were observed (controls: 64 and 42). For specimens polished after 24 h, a significantly (p < 0.05) reduced number of 8-17 summed gaps occurred for only 3 flowable composites; whereas for 5 flowable composites there were non-significantly-different (p > 0.05) numbers (11-17) of summed gaps (controls: 28 and 22). After 24h storage, shear bond-strengths to enamel and to dentin, flexural strengths and moduli increased highly significantly (p < 0.001) for all materials, except Silux Plus. SIGNIFICANCE: A post-cure interval of 24 h resulted in enhanced mechanical and adhesive properties of flowable dental composites. In a minority of cases there was also a reduced incidence of marginal-gap formation. However the latter effect may be partly attributed to 24 h delayed polishing, even though such a delay is not usual clinical practice.