[Three-dimensional imaging for quantitative evaluation of facial profile of edentulous patients before and after complete dentures restoration].

OBJECTIVE: To collect and analyze the Three-dimensional (3D) facial profile variation of edentulous patients restored by complete denture. METHODS: The 3D facial images of 20 Atwood Class II edentulous patients were taken by DSC-2 3D facial imaging system before and after restoration of complete denture. Then, the two 3D facial images of each patient before and after restoration were registered in the same coordinate system by partial structure overlap. The differences between these two 3D facial images were statistically analyzed. RESULTS: The major facial profile variation of Atwood Class II edentulous patients restored by complete denture focused in the area around the upper lip and the corner of the mouth. The change of lower lip and chin area was not obvious. The shift in the sagittal direction was significantly more evident than that in the vertical direction, while the shift in the horizontal direction was the least one. CONCLUSION: The pattern of facial profile variation of edentulous patients restored by complete denture based on 3D imaging may provide reliable data support for prediction and communication in clinical practice.

[The effect of simulate intraoral sandblasting on the band strength between enamel and composite resin].

OBJECTIVE: To study whether the bond strength between enamel and composite resin could be enhanced by intraoral sand abrasive. METHODS: Ten human maxillary first incisior teeth were divided into 2 groups The experimental group was sandblasted with 30 microm Al2O3 (CoJet-Sand, pressure 300 kPa) from a distance of 5 mm for 5 seconds, and the control group were not sandblasted. The Herculite composite resin composite cylinders were bonded with Coltene system. Bonded specimens were stored in 37 degrees C distilled water for 24 h, then were subjected to shear force in a testing machine. Stress at failure was calculated in Mpa, and mode of failure was recorded. The Student t test was applied to the data. RESULTS: The shear bond strength of experimental groups was (33.0+/-1.8) MPa, and that of control groups was (26.7+/-5.2) MPa,there was significant difference between these two groups. All the adhesive failures happened at the enamel composite resin interface, except that cohesive failure happened in one sandblasted specimen. CONCLUSION: Intraoral sandblasting could significantly enhance the shear bond strength between enamel and composite resin.