Toxicology and side effects of components from dental materials

Comonomers and monomers are used as dental restorative materials. Unconverted compounds can be released from dental composites and can enter the body in humans. It was shown in vitro that dental methacrylates were released into the adjacent biophase from such materials during the first days after placement. In the following study the uptake, distribution, and excretion of radiolabelled [14C]TEGDMA (triethyleneglycoldimethacrylate) applied via gastric and intravenous administration were examined in vivo in guinea pigs. [14C]TEGDMA was taken up rapidly from the stomach and intestine after gastric administration and was widely distributed in the body following administration by each route. Most [14C] was excreted within one day as 14CO2. The peak equivalent TEGDMA levels in guinea pig tissues examined were at least one-thousand-fold less than known toxic levels. However in further studies it could be demonstrated that in the metabolism of TEGDMA, HEMA (hydroxy-ethylmethacrylate) and BisGMA (bis-phenolglycidylmethacrylate) the toxic intermediate 2,3-epoxy- methacrylate can be formed. Epoxides are regarded as mutagenic and carcinogenic compounds.

During the last decade a dramatic increase of allergies is observed in dentists, dental personnel and patients caused by methacrylic dental composite components. Methylmethacrylate (MMA), HEMA and TEGDMA have high allergic potentials and can cause respiratory diseases and contact dermatitis. MMA-concentrations up to 30 mg/m3 were found in the air of dental practices/laboratories. For an allergic risc assessment of patients it is important to know the quality and quantity of compounds eluted from dental composites.

The further study was evaluated to qualify and to quantify eluted compounds from various dental composites. Following composites were tested (producer in parentheses): Els extra low shrinkage/ELS (Saremco), Synergy Duo Shade/SDS (Coltène), Grandio (VOCO), Tetric Evo Ceram/TEC (Vivadent), Venus (Kulzer), Gradia (G.C.), and Premise (Kerr).

Polymerized composites (100 mg) were incubated in GC vials with 1 ml dest. water or 1 ml methanol, each at 37 °C for 72 hours. Aliquots were taken, and eluted compounds were analyzed with the method of gas chromatography/mass spectrometry (GC-MS) and liquid chromatography/mass spectrometry (LC-MS). From all composites 18 different compounds were found. Following comonomers were quantified (µg/ml; mean, s.d. in parentheses; n=3; n.d.= not detectable/below limit of detection):

TEGDMA (water): Premise 48(7), Gradia 123(18), Venus 197(26), TEC 57(12), Grandio 36(5), SDS 104(16), ELS n.d..

HEMA (water): n.d. in all composites.

TEGDMA (methanol): Premise 51(9), Gradia 62(2), Venus 76(7), TEC n.d., Grandio 68(12), SDS 126(23), ELS n.d.

HEMA (methanol): Premise n.d., Gradia 500(66), Venus n.d., TEC 496(77), Grandio n.d., SDS n.d., ELS n.d.

Triphenylstibane was detected in TEC (5 ± 2 µg/ml).

Following range of the eluted and detected comonomers from dental composites was found (dest. water; decreasing elution): Venus > Gradia > Synergy Duo Shade > Tetric Evo Ceram Premise > Grandio > Els Extra low shrinkage.

Conclusion:

Patients with existent allergy against (co)monomer(s) should not receive any composite which can eluate this/these comonomer(s).