Influence of water sorption on mechanical properties of injection-molded thermoplastic denture base resins.
OBJECTIVE
This study investigated the influence of water sorption on certain mechanical properties of injection-molded thermoplastic denture base resins.


METHODS
Six thermoplastic resins (two polyamides, two polyesters, one polycarbonate, one polymethylmethacrylate) and a polymethylmethacrylate (PMMA) conventional heat-polymerized denture-based polymer, selected as a control, were tested. Specimens of each denture base material were fabricated according to ISO 1567 specifications and were either dry or water-immersed for 30 days (n = 10). The ultimate flexural strength, the flexural strength at the proportional limit and the elastic modulus of the denture base materials were calculated.


RESULTS
Water sorption significantly decreased the ultimate flexural strength, the flexural strength at the proportional limit and the elastic modulus of one of the polyamides and the PMMAs. It also significantly increased the ultimate flexural strength of the polycarbonate.


CONCLUSIONS
The mechanical properties of some injection-molded thermoplastic denture base resins changed after water sorption.
Division of Removable Prosthodontics, Fukuoka Dental College , Fukuoka , Japan.
Ippei
I
Hamanaka
Misa
M
Iwamoto
Lippo
L
Lassila
Pekka
P
Vallittu
Hiroshi
H
Shimizu
Yutaka
Y
Takahashi
D065966:Absorption, Physicochemical; D000327:Adsorption; D003764:Dental Materials / Q000737:chemistry*; D003819:Denture Bases; D055119:Elastic Modulus; D006801:Humans; D007101:Immersion; D008422:Materials Testing; D009757:Nylons / Q000737:chemistry; D018583:Pliability; D011076:Polycarboxylate Cement / Q000737:chemistry; D011091:Polyesters / Q000737:chemistry; D058105:Polymerization; D019904:Polymethyl Methacrylate / Q000737:chemistry; D012117:Resins, Synthetic / Q000737:chemistry*; D013314:Stress, Mechanical; D013997:Time Factors; D014867:Water / Q000737:chemistry*
D003764:Dental Materials; D009757:Nylons; D011076:Polycarboxylate Cement; D011091:Polyesters; D012117:Resins, Synthetic; D014867:Water; C005506:polycarbonate; D019904:Polymethyl Methacrylate
injection-molded thermoplastic denture base resin; polyamide; polycarbonate; polyethylene terephthalate copolymer; water sorption