Distal Extension Removable Partial Dentures

According to a photoelastic study of support structures in RPD [1]: The distribution of of tension was influenced by the type of retainer, the length of the saddle and by the form of load application. In relation to the retainer, a more equal distribution of forces between the support structures was seen in the RPI retainer, followed by the T-bar and by the circumferential reatiners. As for the saddle length a more equal distribution of forces between the support structures was observed on the long saddles as the dentures with short saddles induced a greater concentration of tensions on the residual ridge. The best distribution of tensions occurred when the load was uniformly distributed, while the load localized on the last artificial tooth induced greater concentration of tensions on the residual ridges.

Reference
1. Costa MM, da Silva MAMR, Oliviera SAGO, Gomes VL, Carvalho PM Lucas BL: Photoelastic study of the support structures of distal-extension removable partial dentureJ Prosthodontics 2009;18:589-595

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Causes of Injury in Fixed Partial Denture Tooth Preparation

Causes of Injury in Fixed Partial Denture Tooth Preparation

Causes of Injury in Tooth Prep


Temperature

Considerable heat is generated by friction between a rotary instrument and the surface being prepared. Excessive pressure, higher rotational speeds, and the type, shape and condition of cutting instrument. Feather light touch and water spray should be used.

Chemical Action

The chemical action of some dental materials (bases, restorative resins, solvents and luting agents) can caused pulpal damage.

Bacterial Action

Pulpal damage under restorations has been attributed to bacteria that either were left behind or gained access to the dentin because of microleakage. Antimicrobial agent after tooth preparation and before cementation should be used.

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