THE MECHANICS OF DENTAL RETENTIVE PINS AND IMPRESSION MATERIALS.
Final rept. 1 Jun 68-31 Dec 69,
ROCKETDYNE CANOGA PARK CALIF
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Initial studies are reported of problems of a dental retentive pin installation and loading, and b deformation of dental impression materials employing photoelastic and other techniques common to mechanical investigations of materials. Pin installation and loading stresses in dentinal tissue were identified. Cracking and crazing of dentin were discovered relating to pin installation. Stress and failure phenomena were related to clinical factors in channel drilling, pin type and quality, insertion parameters, and applied loads. Mercaptan rubber impression removal stresses were determined, analyzed, and related to parameters of tray rigidity, bulk of impression, degree of undercut, and direction and rate of removal. No permanent deformations were noted. Agar-agar hydrocolloid impression material was determined to be birefringent. Author
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