Synthesis and Characterization of a Ring-Opening Oxaspiro Comonomer by a Novel Catalytic Method for Denture Base Resins.

Background: 3,9-Dimethylene-1,5,7,11-tetraoxaspiro[5,5]undecane (DMTOSU) is a double ring-opening monomer that exhibits expansion upon polymerization and may be used as a denture base resin's comonomer to offset or minimize polymerization shrinkage. It's synthesis by transesterification reaction (TE) catalyzed by distannoxane is not reported in the literature. The synthesis became the prime concern because this monomer is hardly available commercially.

Influence of Cortical Layer and Surgical Techniques on the Primary Implant Stability in Low-density Bone: An Study.

Aim: This study aimed at evaluating the influence of cortical layer and surgical techniques on the primary stability of implants in low-density bone.

Materials And Methods: Two solid rigid polyurethane blocks with a density equivalent to 0.32 g/cm simulating cancellous bone were used.