Related Experiment Videos
Cuspal movement and microleakage in premolar teeth restored with resin-based filling materials cured using a
G J P Fleming1, R R Cara, W M Palin
1Materials Science Unit, Division of Oral Biosciences, Dublin Dental School & Hospital, Trinity College Dublin, Dublin 2, Ireland. garry.fleming@dental.tcd.ie
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.