In a curved tube, the amount of airflow appears to be influenced by the amount of curvature. The purpose of this study was to investigate changes in obstructive sleep apnoea (OSA) severity and awake velopharyngeal curvature in response to an anteriorly titrated mandibular position in 20 male OSA patients.Baseline supine cephalometry was obtained before the initial insertion of a titratable oral appliance and follow-up supine cephalometry was undertaken after titration of the mandibular position with the appliance in place.The mean apnoea/hypopnea index (AHI) before treatment (31.6¡13.0 events?h -1 ) was significantly reduced (9.8¡7.4 events?h -1 ) after titration of the mandibular position in all 20 patients. There was a significant increase in the anteroposterior calibre and the radius of the curvature of the anterior wall of the velopharynx in 14 good responders who exhibited an AHI reduction to f15. Similar observations were not found in six poor responders.To conclude, an anteriorly titrated mandibular position reduced obstructive sleep apnoea severity, enlarged the velopharynx and diminished the curvature of the anterior velopharyngeal wall in good responders. It is proposed that this change in the upper airway curvature associated with mandibular advancement may effect obstructive sleep apnoea severity through its effect on airflow dynamics. The fluid flow through curved tubes in human organs such as the aortic arch and the coronal arteries are of interest physiologically in the study of cardiovascular systems, since an increase in the curvature induces pressure losses as well as higher resistance in the same region [1,2]. The upper airway (UA) has characteristics similar to those of the curved vessels in the cardiovascular system in that the airstream is curved from the nasal cavity to the hypopharynx at the level of the velopharynx. Nevertheless, an interaction between the curvature of the velopharynx and the pathogenesis of obstructive sleep apnoea (OSA) remains unknown.Recent developments in mandibular advancement oral appliances (OAs) have provided a better quality of life not only for patients with snoring and mild-to-moderate OSA, but also for severe OSA patients who could not tolerate nasal continuous positive airway pressure (nCPAP) [3,4]. An anterior titration of the mandibular position using OAs has been reported to increase the anteroposterior diameter [5] and cross-sectional area [6] of the velopharynx, resulting in a reduction of OSA severity. In addition to such anatomical changes, it was reported that advancement of the mandible decreased nasal resistance and facilitated nasal breathing [7,8]. These reports indicate a close relationship between morphological alteration and improvement of airflow dynamics in response to mandibular protrusion. If the anterior titration of the mandibular position decreased the curvature of the velopharynx, it may assist in improving airflow dynamics.It was hypothesised that an anteriorly titrated mandibular position would diminish the curvature of t...

The purpose of this study was to duplicate the shapes of complete dentures by using a computeraided design/manufacturing (CAD/CAM) system. Theshapesof the complete dentures of an edentulous patient were measured using a non-contact type shape measurement system and morphological data at the interval of 0-25 mm were obtained in the X-axis and Y-axis directions. Measurement was performed from the occtusat surface and mucosal surface sides. Based on the three-dimensional morphological data, cutter paths for cutting were generated. For cutting, the three-step method consisting of rough cutting. finish cutting, and partial finish cutting was used and for duplicating the dentures the modelling wax was cut using a computerized numerical control (CNC) processor and ball-end mills with diameters of 6 mm and I mm. The method for the controlling of three axes (X, Y, and Z) of CNC machine was used, and cutting was performed only from two directions. Although further improvements are needed in the measurement and cutting in acute slope areas, the duplication of complete dentures appears to be possible using the CAD/CAM system.

Complete dentures change the soft-tissue profile, although the exact relationship remains unclear. This study examined the relationship between the presence and degree of lip support provided by dentures and the lateral views of the facial appearance of edentulous patients. The subjects were five edentulous patients (three men and two women). Their facial appearances with experimental record blocks, with and without their complete dentures, were measured using a three-dimensional laser measuring system. The experimental record block for each subject had different conditions in the anteroposterior direction anteriorly but the same vertical dimensions posteriorly. The lateral digital facial images were displayed on a computer monitor, and the linear and angular measurements were analysed using image analysis software. The nasolabial angle was smaller and the labial points projected more with excessive lip support versus with deficient support. Moreover, the counter of the nose was affected by the labial flange of the record base, particularly in the facial appearance of one subject with highly atrophic residual ridges. The lip support affected the lower facial soft-tissue profile, including the lower part of the nose; the nasolabial angle and positional relationship between the lips and Ricketts's esthetic plane (E plane) are useful indexes for examining lip support.

A method of measuring the elastic modulus of oral soft tissue was developed and used to determining the elastic moduli of oral soft tissue in two patients and of two elastomeric impression materials. The elastic modulus of oral soft tissue varied considerably according to positions measured and became slightly higher, compared with that of elastomeric impression materials. These results suggest that the accuracy of dental impression is affected by the viscoelastic properties of oral soft tissue. The developed instrument was also found to be appropriate for the comparative assessment of rheological properties of oral soft tissue and impression material.

The purpose of this study was to duplicate the shapes of complete dentures by using a computer-aided design/manufacturing (CAD/CAM) system. The shapes of the complete dentures of an edentulous patient were measured using a non-contact type shape measurement system and morphological data at the interval of 0.25 mm were obtained in the X-axis and Y-axis directions. Measurement was performed from the occlusal surface and mucosal surface sides. Based on the three-dimensional morphological data, cutter paths for cutting were generated. For cutting, the three-step method consisting of rough cutting, finish cutting, and partial finish cutting was used and for duplicating the dentures the modelling wax was cut using a computerized numerical control (CNC) processor and ball-end mills with diameters of 6 mm and 1 mm. The method for the controlling of three axes (X, Y, and Z) of CNC machine was used, and cutting was performed only from two directions. Although further improvements are needed in the measurement and cutting in acute slope areas, the duplication of complete dentures appears to be possible using the CAD/CAM system.