N-acetyl cysteine alleviates inflammatory reaction of oral epithelial cells to poly (methyl methacrylate) extract.
OBJECTIVE
The purpose of this in vitro study was to determine whether the cytotoxicity of self-curing polymethyl methacrylate (PMMA) dental resin to oral epithelial cells was eliminated by mixing the antioxidant amino acid derivative, N-acetyl cysteine (NAC) with the material.


METHODS
Rat and human oral epithelial cells cultured on polystyrene were incubated in culture medium with or without extract from self-curing PMMA dental resin, with or without pre-mixing with NAC. On day 1, the cultures were evaluated for cellular damage, intracellular formaldehyde invasion, cellular redox status and pro-inflammatory cytokine production. Formaldehyde content and the amount of released NAC in the extract were evaluated.


RESULTS
Rat epithelial cells cultured with PMMA extract showed marked increases in lactate dehydrogenase (LDH) release, intracellular formaldehyde and lysosomal levels and reductions in attached cell number and the amount of E-cadherin compared with those in the culture without the extract; these adverse biological effects were alleviated or prevented by pre-mixing the resin with NAC. In human oral epithelial cells cultured with PMMA extract, the addition of NAC into the resin prevented the intracellular elevation of reactive oxygen species and the reduction in cellular glutathione levels. Human cell cultures with the extract produced higher levels of various pro-inflammatory cytokines than cultures without the extract; this was prevented by mixing the resin with NAC. The extract from PMMA pre-mixed with NAC contained a lower concentration of formaldehyde and a substantial amount of antioxidants.


CONCLUSIONS
The cytotoxicity of self-curing PMMA dental resin to oral epithelial cells was eliminated by mixing the resin with NAC.
Department of Removable Prosthodontics and Gerodontology, Tokyo Dental College , Tokyo , Japan.
Hiroko
H
Nishimiya
Masahiro
M
Yamada
Takayuki
T
Ueda
Kaoru
K
Sakurai
D000111:Acetylcysteine / Q000737:chemistry / Q000494:pharmacology*; D000818:Animals; D000975:Antioxidants / Q000032:analysis; D015820:Cadherins / Q000032:analysis; D002448:Cell Adhesion / Q000187:drug effects; D002452:Cell Count; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D016207:Cytokines / Q000032:analysis; D004847:Epithelial Cells / Q000187:drug effects / Q000276:immunology; D005557:Formaldehyde / Q000032:analysis; D005978:Glutathione / Q000032:analysis; D006801:Humans; D018836:Inflammation Mediators / Q000032:analysis; D007770:L-Lactate Dehydrogenase / Q000032:analysis; D008247:Lysosomes / Q000187:drug effects; D008297:Male; D009061:Mouth Mucosa / Q000166:cytology / Q000187:drug effects* / Q000276:immunology; D010084:Oxidation-Reduction; D019904:Polymethyl Methacrylate / Q000737:chemistry / Q000633:toxicity*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000032:analysis; D013997:Time Factors
D000975:Antioxidants; D015820:Cadherins; D016207:Cytokines; D018836:Inflammation Mediators; D017382:Reactive Oxygen Species; D005557:Formaldehyde; D019904:Polymethyl Methacrylate; D007770:L-Lactate Dehydrogenase; D005978:Glutathione; D000111:Acetylcysteine
Acrylic resin; mucositis; oxidative stress; pro-inflammatory cytokine; prosthesis