RESUMO
Deep curve of Spee is a very common problem among Class II malocclusion patients associated with mandibular deficiency. The curve of Spee is maintained and leveled following surgical mandibular advancement. The same surgical splint which is used to guide the mandibular advancement can also be used for the leveling of deep curve of Spee. This case report highlights the leveling of deep curve of Spee by the same surgical splint used during the surgical mandibular advancement. Thus, it helps to increase the lower facial height and also improves the overall facial appearance.
RESUMO
In this study, the effect of the grain boundary density on the transport properties of the Re-substituted higher manganese silicide Mn30.4Re6Si63.6 has been investigated. The efficiency of electrical energy conversion from waste heat, mainly in thermoelectric generators, depends on how the thermal conduction is reduced, while the charge-carrier electrons/holes contribute to possess a large magnitude of both the electrical conductivity σ and Seebeck coefficient S. In this work, we tried to obtain such a condition with a novel approach of merging the energy-filtering effect at the grain boundaries to improve the power factor (PF) = S2σ. The nanostructuring and heavy-element substitution were also employed to greatly scatter the phonon conduction. As a result, enhancement of the PF was observed in the diffused nanostructure of annealed ribbon samples, and the enhancement was correlated with the formation of Schottky barriers at the grain boundary interface. Together with a reduction of the thermal conductivity to very low magnitude 1.27 W m-1 K-1, we obtained a maximum ZT = 1.15 at 873 K for the annealed ribbon samples.
RESUMO
BACKGROUND: The use of functional appliances for the correction of retrognathic mandible is very common in orthodontics. Similar appliances known as oral appliances are also frequently used in adults for the treatment of mild to moderate obstructive sleep apnea (OSA). Many studies have reported improvement of pharyngeal airway passage (PAP) dimensions following functional appliance therapy in children and oral appliance therapy in adults. There is only one study in the literature that discussed the effect of oral appliance therapy on posterior pharyngeal wall thickness (PPWT) among subjects with OSA. The effect of functional appliance therapy on PPWT has never been investigated. Thus the present study was conducted to evaluate the effects of twin-block appliance on pharyngeal airway passage (PAP) dimensions and posterior pharyngeal wall thickness (PPWT) in class II malocclusion subjects with retrognathic mandibles. METHODS: Thirty-eight class II malocclusion subjects in the age range of 8 to 14 years with mandibular retrusion were divided into a treatment (n = 20) and control (n = 18) group. Mandibular retrusion in the treatment group subjects was corrected by twin-block appliance. The effect of twin-block appliance on PAP and PPWT dimensions were evaluated from lateral cephalograms recorded prior-to and after 6 months of appliance therapy in the treatment group subjects and the changes were compared with the changes in the control group subjects. Student's t-test was used for statistical analysis; P-value of 0.05 was considered a statistically significant level. RESULTS: The depth of the oropharynx was increased significantly in the treatment group subjects (P < 0.001) as compared to the control group subjects (P < 0.05). The depth of the hypopharynx increased significantly in treatment group subjects (P < 0.01). The PPWT at the level of the nasopharynx, oropharynx, and hypopharynx were maintained in the treatment group subjects; whereas in control group subjects, the PPWT was further reduced although the changes were not statistically significant. CONCLUSIONS: Correction of mandibular retrusion by twin-block appliance in class II malocclusion subjects increased the PAP dimensions and maintained the pre-treatment thickness of posterior pharyngeal wall.
