The Effect of Food-Simulating Agents on the Bond Strength of Hard Chairside Reline Materials to Denture Base Resin.

PURPOSE: To investigate the influence of food-simulating agents on the shear bond strength between direct hard liners and denture base acrylic resin. In addition, mode of failure was evaluated. MATERIALS AND METHODS: One hundred fifty cylindrical columns of denture base resin were fabricated and bonded to three types of hard reline materials (Hard GC Reline, Tokuyama Rebase II Fast, TDV Cold Liner Rebase). Specimens of each reline material were divided into five groups (n = 10) to undergo 12-day immersion in distilled water, 0.02 N citric acid aqueous solution, heptane, and 40% ethanol/water solution at 37°C. The control group was not immersed in any solution. The shear bond strength test was performed, and the failure mode was determined. Statistics were analyzed with two-way ANOVA and chi-square test (α = 0.05). RESULTS: Significant interaction was found between the hard liners and food simulating agents (p < 0.001). The shear bond strength of Tokuyama in 40% ethanol and TDV in heptane decreased significantly (p = 0.001, p < 0.001 respectively); however, none of the solutions could significantly affect the shear bond strength of Hard GC Reline (p = 0.208). The mixed failure mode occurred more frequently in Hard GC Reline compared with the other liners (p < 0.001) and was predominant in specimens with higher bond strength values (p = 0.012). CONCLUSIONS: Food simulating agents did not adversely affect the shear bond strength of Hard GC Reline; however, ethanol and heptane decreased the bond strength of Tokuyama and TDV, respectively. These findings may provide support to dentists to recommend restricted consumption of some foods and beverages for patients who have to use dentures relined with certain hard liners.

Four experimental stimulants found in sports and weight loss supplements: 2-amino-6-methylheptane (octodrine), 1,4-dimethylamylamine (1,4-DMAA), 1,3-dimethylamylamine (1,3-DMAA) and 1,3-dimethylbutylamine (1,3-DMBA).

BACKGROUND: The United States Food and Drug Administration banned the stimulant 1,3-dimethylamylamine (1,3-DMAA) from dietary supplements and warned consumers that the stimulant can pose cardiovascular risks ranging from high blood pressure to heart attacks. OBJECTIVES: We designed our study to determine if a new stimulant similar in structure to 1,3-DMAA has been introduced as an ingredient in supplements sold in the United States (US). METHODS: We analyzed six brands of supplements that listed an ingredient on the label (e.g., Aconitum kusnezoffii, DMHA or 2-amino-isoheptane) that might refer to an analog of 1,3-DMAA. Supplements were analyzed by two separate laboratories using ultra-high-performance liquid chromatography mass spectrometry and reference standards. RESULTS: Two previously unidentified 1,3-DMAA analogs (2-amino-6-methylheptane [octodrine] and 1,4-dimethylamylamine [1,4-DMAA]) and two banned stimulants (1,3-DMAA and 1,3-dimethylbutylamine [1,3-DMBA]) were identified. Octodrine was found at a dose (±95% CI) of 72 ± 7.5 mg per serving. In Europe, octodrine was previously sold as a pharmaceutical in multi-ingredient medications at dosages from 8 to 33 mg. The quantity of octodrine found in our study was more than twice the largest pharmaceutical dose. The other new stimulant, 1,4-DMAA, has not previously been approved for human consumption, and its safety in humans is unknown. 1,4-DMAA was found at dosages between 21 ± 11 mg to 94 ± 48 mg per serving. In addition, two banned stimulants - 1,3-DMAA and 1,3-DMBA - were also identified: 24 ± 7.6 mg to 35 ± 11 mg of 1,3-DMAA and 51 ± 16 mg of 1,3-DMBA. In one product, 24 ± 7.6 mg of 1,3-DMAA was combined with 21 ± 11 mg of 1,4-DMAA. 1,3-DMAA has been investigated as potentially contributing to hemorrhagic strokes and sudden death, whereas the safety of 1,3-DMBA in humans is unknown. CONCLUSION: Two banned stimulants (1,3-DMAA and 1,3-DMBA) and two previously unidentified stimulants (1,4-DMAA and octodrine) were identified in supplements sold in the United States.

Pulmonary toxicity following exposure to an aerosolized leather protector.

BACKGROUND: An aerosol spray for leather protection was reformulated to remove trichloroethane. The new formulation contained isobutane, n-heptane, ethyl acetate and fluoroaliphatics. RETROSPECTIVE REVIEW: Thirty-nine patients reported symptoms to the regional poison center. Respiratory symptoms developed within hours of exposure. Most symptoms resolved within two days. Abnormal pulmonary function tests, including obstructive disease or diminished diffusing capacity, were demonstrated in three of the four tested patients. CONCLUSIONS: The mechanism for the pulmonary toxicity has not been determined.

[Exposure to glues containing technical heptane: a clinical and electrophysiological study]. / Esposizione a collanti contenenti eptano tecnico: studio clinico ed elettroneurofisiologico.

Polyneuropathy caused by n-hexane contained in glues was, until recently, the typical occupational disease of shoemakers. Glues no longer contain large concentrations of this solvent, and in some cases, it as been completely replaced by other hydrocarbons. The authors investigated the health status in a group of shoemakers using glues containing 35% technical heptane. The same glue, not containing n-hexane, was used by a shoemaker who worked at home; she developed an otherwise unexplainable peripheral polyneuropathy. For each of the 16 subjects, the following procedures were carried out: environmental sampling, biological monitoring for Mek and heptane metabolites, a neurological and electromyographic examination. No neurological abnormalities were found in the workers that could be attributable to occupational exposure, probably due to the low level environmental contamination (< 100 mg/m3 n-heptane) found in the 7 factories and workshops studied where acceptable hygiene conditions existed. The time course and ratio of urinary metabolites of heptane were also studied, the latter showing a predominance of 2- and 3- heptanol in the initial phase and 2-5 heptandione at the end of the work week; probably, the presence of other solvents, such as Mek, can modify the ratio of metabolites and consequently the formation of neurotoxic compounds could result.

Does n-heptane cause peripheral neurotoxicity? A case report in a shoemaker.

Subjective and electrophysiological signs relating to the central and peripheral nervous systems developed in a shoemaker, a few months after beginning work at home. Signs of central nervous system involvement rapidly disappeared after the end of the exposure, whereas those of mild peripheral neuropathy lasted for several months. The glue used contained a variety of solvents including ethylacetate, cyclohexane, methylcyclohexane, methylethylketone and others; n-hexane was not detected, whereas, unusually, n-heptane was. This exposure was reproduced experimentally in the same work room and the solvent air level did not exceed the American Conference of Governmental Industrial Hygienists threshold values. A tentative conclusion is that the toxic effects on the peripheral nerve are likely to be due to n-heptane.

[Peripheral neuropathy due to N-hexane in a drug addict (author's transl)]. / Neuropathie périphérique au N-hexane chez une toxicomane.

After voluntary inhalation of a domestic solvent containing N-Hexane and N-Heptane for three months, a 23-year-old woman developed motor deficit of the lower limbs, sensory symptoms and areflexia. Clinical disorders continued to progress after discontinuation of the intoxication, with a parallel aggravation of the E.M.G. disturbances. A nerve biopsy with ultrastructural study showed axon dilatation with accumulation of neurofilaments. The clinical, electrophysiological and pathological features of neuropathies induced by hexacarbon solvents are reviewed and their pathogenesis is discussed.