PMID- 15707433
OWN - NLM
STAT- MEDLINE
DCOM- 20050614
LR  - 20061115
IS  - 0305-182X (Print)
IS  - 0305-182X (Linking)
VI  - 32
IP  - 3
DP  - 2005 Mar
TI  - Effect of curing environment on mechanical properties and polymerizing behaviour 
      of methyl-methacrylate autopolymerizing resin.
PG  - 221-6
AB  - Methyl-methacrylate autopolymerizing resin is used for multiple applications. 
      Therefore, the mechanical properties of autopolymerizing resin should be assessed 
      comprehensively including strength, stiffness and hardness. Any methods that 
      effectively improve these mechanical properties are desirable. The objective of 
      this study is to examine the effects of the curing environment: air or water 
      with/without pressure, and air or water temperature during polymerization, on the 
      strength, stiffness and hardness of autopolymerizing resin. In addition, we 
      examined the polymerizing behaviour associated with the mechanical properties. 
      Autopolymerizing methyl-methacrylate resin (Unifast II) was polymerized under the 
      following conditions: in air and water with/without pressure at 10, 23, 30, 40, 
      60 and 80 degrees C. The resin specimens were subjected to a transverse test 
      (three-point flexural test) and micro-Brinell surface hardness test. Fractured 
      surfaces of the specimens after the transverse test were examined using a 
      scanning electron microscope (SEM). The transverse strength and transverse 
      modulus increased with increasing curing temperature in both wet and dry 
      conditions. Pressured wet conditions increased transverse strength and transverse 
      modulus over non-pressured wet and dry conditions. The resin polymerized in dry 
      conditions showed higher surface hardness than the one polymerized in wet 
      conditions at matching temperature. The SEM images of fractured surfaces cured at 
      lower temperature exhibited porosity within the polymer base and cracks between 
      the base and poly-methyl-methacrylate (PMMA) particulates. Surfaces of the resin 
      polymerized in wet conditions were characterized with PMMA particulates having 
      rougher surfaces suggestive of water incorporation. Raising temperature and 
      pressuring during polymerization increase strength and stiffness of 
      autopolymerizing resin. However, wet condition reduces surface hardness of resin 
      compared with dry condition. These altered mechanical properties are associated 
      with polymerization behaviour of the resin.
FAU - Ogawa, T
AU  - Ogawa T
AD  - The Jane and Jerry Weintraub Center for Reconstructive Biotechnology, Division of 
      Advanced Prosthodontics, Biomaterials and Hospital Dentistry, UCLA, Los Angeles, 
      CA 90095-1668, USA. tack@dent.ucla.edu
FAU - Hasegawa, A
AU  - Hasegawa A
LA  - eng
PT  - Comparative Study
PT  - Journal Article
PL  - England
TA  - J Oral Rehabil
JT  - Journal of oral rehabilitation
JID - 0433604
RN  - 0 (Acrylic Resins)
RN  - 0 (Composite Resins)
RN  - 0 (unifast II)
SB  - IM
MH  - *Acrylic Resins
MH  - *Composite Resins
MH  - Hardness
MH  - Humans
MH  - Materials Testing
MH  - Microscopy, Electron, Scanning
MH  - Temperature
EDAT- 2005/02/15 09:00
MHDA- 2005/06/15 09:00
CRDT- 2005/02/15 09:00
PHST- 2005/02/15 09:00 [pubmed]
PHST- 2005/06/15 09:00 [medline]
PHST- 2005/02/15 09:00 [entrez]
AID - JOR1406 [pii]
AID - 10.1111/j.1365-2842.2004.01406.x [doi]
PST - ppublish
SO  - J Oral Rehabil. 2005 Mar;32(3):221-6. doi: 10.1111/j.1365-2842.2004.01406.x.