M W Bides | PubMed Health

PubMed1995

Strain profiles in molars restored with posterior composite resins: effect of cavity size & restorative technique.

The objective of the study was to quantitatively compare peak strain in buccal & lingual aspects of human molar teeth restored with composite res in polymers as a function of: 1) cavity size, 2) restorative material, 3) restorative technique. Two composite resin materials were investigated: Herculite (sub micron filler particle) & P 50 (supra micron filler particle). Performance was compared to two different types of high copper amalgams. A total of 48 freshly extracted human molar teeth free from cracks or caries were used. MOD cavities were prepared with three different cavity sizes: 1 mm, 2.5 mm & 5 mm. Rectangular rosette strain gauges were applied centrally on the buccal & lingual surfaces of the prepared teeth. Strain measurements were recorded during subsequent cavity restoration procedures and curing cycles. A comparison of peak strains in the amalgam vs composites using bulk-pack technique showed significantly higher strain in the composite series. Highest strains were noted in the largest cavity size (5 mm). Slot preparation following restoration reduced strains in the composite materials. Subsequent re-filling of the slot increased strain, but still less than the initial value.

Analysis of Variance↗

PubMed1994

Implant-protected occlusion.

Implant-Protected Occlusion is that occlusal scheme which reduces the forces at the crestal bone/implant interface. Biomechanical principles form the basis of this concept. The direction of force, force magnification, and implant position relative to arch or location are blended together for a consistent approach to implant reconstruction. The direction of force demonstrates that angled forces increase the type of forces, alter their point of application, and reduce bone strength. Force magnifiers include cantilevers, offset loads, and monumental forces to the implant body. These magnifiers dramatically increase the among of force applied to a prosthesis. The implant position relative to arch or arch position often determines the density of bone and the amount of force. Adequate surface area of implant bodies considers width, length, and number. The surface area is a primary component in the resistance of force factors. In addition occlusal table width and occlusal contacts contribute to the force amount type and direction and may be modified to reduce crestal loads.

Bite Force↗