No abstract

The 2D ultrasonography was used to evaluate the prevalent type of swallowing in children with ULCB. Visceral type of swallowing pattern and the changed tongue function during swallowing seem to be important factors in the aetiology of ULCB.

The aim of this study was to determine whether a force applied in an antero-posterior direction would adequately reduce incisor eruption. This is needed to achieve a constant direction of force which is one of the demands for a good model for studying orthodontic tooth movement. Twenty male Wistar rats aged 11-12 weeks were divided into two equal groups: in the appliance group, a superelastic closed coil spring (25 cN) was placed between the upper left first molar and the incisors. The control group consisted of animals without an appliance. In both groups, cuts were created on the labial surfaces of the upper and lower incisors. The distance from the gingival reference point to the midpoint of the cut was measured for 10 days at 2 day intervals. Upper incisor inclination was determined as the distance from the most mesial point of the upper left first molar to the incisal edge of the ipsilateral incisor on days 0 and 10. Statistical analysis was carried out using two-way analysis of variance and a Bonferroni post- test to estimate reliability. The eruption rates of the maxillary incisors in the appliance group were significantly decreased when compared with the control group during the whole experiment. In the appliance group, the eruption rates of the mandibular incisors were decreased more than those of the maxillary incisors (P<0.01). There was no difference in incisor inclination between the appliance and control groups on day 10 (P=0.81). The applied force of 25 cN in an antero-posterior direction diminished incisor eruption to a level which enabled a constant direction of orthodontic force for 10 days.

Many chemical messengers are involved in the process of alveolar bone and periodontal ligament remodelling during orthodontic tooth movement. Among them is probably endothelin-1 (ET-1). Its role in this process has been partly explained using tezosentan, which affects endothelin A (ET(A)) and endothelin B (ET(B)) receptors. Tezosentan enhances orthodontic tooth movement. The aim of this study was to determine the possible effects of a highly selective ET(A) antagonist on orthodontic tooth movement in rats. Thirty male Wistar rats, 11-12 weeks of age, divided into three equal groups. In group I, a closed-coil spring was used and they were treated daily with 15 mg/kg body weight of TBC3214, a highly selective ET(A) antagonist. A closed-coil spring was also used in group II and the animals were treated daily with a placebo. Group III were treated daily with a placebo. The coil spring delivered a force of 25 cN and was attached between the upper left first molar and upper left incisor. The distance between the teeth was measured with a digital calliper (accuracy +/- 0.01 mm) on days 0, 7, 14, 21, 24, 32, 37, and 40. The differences in the distance between the teeth were calculated to determine the amount of tooth movement. Statistical analysis was performed using two-way analysis of variance, Bonferroni's correction, and paired t-tests. The distance between the upper left first molar and the upper left incisor decreased in groups I and II. In group I, tooth movement was significantly less on days 32 and 37 (P < 0.01) and on day 40 (P < 0.001) compared with group II. In group III, the distance between the teeth increased during the study (P < 0.001). In animals treated daily with TBC3214, tooth movement was significantly less compared with the animals treated with a placebo. It is concluded that ET-1, which is the predominant form of endothelin isopeptides, is involved in orthodontic tooth movement in rats, probably by enhancing bone resorption via ET(A) receptors.