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Active mandibular protrusion in the rational treatment of scheletal class II malocclusion
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Hydrocaffeic and p-coumaric acids, natural phenolic compounds, inhibit UV-B damage to WKD human conjunctival cells in vitro and rabbit eye in vivo
No full textThis paper studied the effect on UV-B ocular damage of 10microM hydrocaffeic acid (HCAF) alone and as a mixture (MIX) (5 microM HCAF+5 microM p-coumaric acid). Since ocular UV-B damage is mediated by reactive oxygen species, the aim was to test if HCAF and MIX could reduce oxidation damage in human conjunctival cells (WKD) in vitro and in cornea and sclera of rabbits in vivo. After UVB irradiation (44 J/m(2)) of WKD cells, 8-oxodG levels in DNA were markedly increased and this effect was attenuated by HCAF and MIX. Rabbit eyes were treated by application of HCAF and MIX drops before UV-B exposure (79 J/m(2)). Corneal and scleral DNA oxidation damage, xanthine-oxidase (XO) activity and malondialdehyde levels (MDA) in corneal tissue and prostaglandin E(2) (PGE(2)) in the aqueous humour were reduced by HCAF alone and in combination with p-coumaric acid, showing their potential as a topical treatment against UV-B damage
Active mandibular protrusion in the rational treatment of skeletal Class II malocclusions
No full textBACKGROUND: Aim of the present study is to assess the ideal mandibular protrusion exercises, which should always be associated with functional treatment of skeletal Class II malocclusions, characterized by mandibular hypoplasia. METHODS: The study was carried out on a sample including 8 growing subjects (mean age 10.6 years +/- 0.6), similar in age and biotypology (mandibular hypoplasia; normodivergent growth pattern). The electromyography (EMG) activity of the superficial bundle of the masseter (considered as an accessory protrusive muscle) was bilaterally recorded at rest and, during voluntary contraction, at different degrees of protrusion (minimum, medium, maximum), condition dynamically analyzed at various times of contraction (initial, 5, 10, 30 seconds). The mean values of the recruitment pattern during the whole contraction, the number of turns/sec and the ratio turns/mean amplitude were evaluated. RESULTS: The data obtained by means of a precise electromyographic analysis suggest that the ideal exercise for an active mandibular protrusion should be a medium degree contraction lasting 10 seconds. These results are consistent with the linear relationship between muscle force and EMG amplitude, correlation effective only up to 60% of the exerted force, because of the muscular fatigue appearing beyond this threshold. During such a muscular fatigue, due to maximum contraction, it is possible to observe a progressive decrease in the EMG activity, owing in particular to the motor-neuron reduced discharge-frequency. CONCLUSIONS: This result suggests a small benefit of long-lasting muscular contractions, both in maximum and in medium protrusion movements, for re-educational purposes. Only during the medium-degree, 10 sec-lasting contraction it's possible to point out a turns-number variation significant of an active and constant contraction, which decreases if long-lasting (30 sec)
Neurophysiological study of active mandibular protrusion in the treatement of skeletal class II malocclusion
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