[A preliminary study on accuracy of implant digital impression].

PURPOSE: To evaluate the accuracy of implant digital impression，in order to provide guidance in digital implant prosthesis. METHODS: According to the requirements, 115 patients undergoing implantation were randomly selected. The implantation impression cap was placed and scanned with CBCT after esteosenesis. Oral cavity was scanned to make the 3D digital implantation model. The model data were obtained by scanning the digital resin implantation models. Based on the remaining teeth, the model data and CBCT data were matched in Nobel Clinicion software. RESULTS: The implantation impression cap in the patient's CBCT was completely matched and overlapped with the digital model in all of the occlusal, coronal and sagittal planes,which meant that the position, direction and angle of the implantation in the oral cavity were exactly the same as those in the digital model made by oral scanning. CONCLUSIONS: 3D digital resin model of oral scanning printing is completely accurate and can be popularized and applied in clinic.

[Study of angle between maxillary incisor and alveolar bone using cone-beam CT].

PURPOSE: To measure the angle between maxillary incisor and alveolar bone by the use of cone-beam CT (CBCT), in order to assess preoperative risks and provide guidance in anterior dental implantation. METHODS: A total of 374 patients were included and divided into 3 age groups: group 1 (18-34 years), group 2 (35-59 years) and group 3(above 60 years). All patients underwent CBCT preoperatively, the angle between maxillary incisor and alveolar bone was measured though Kavo eXam Vision software. The data were analyzed with SPSS16.0 software package for Student's t test. RESULTS: In group 1, 2 and 3, the angle between maxillary incisor and alveolar bone was (13.81±4.37)°, In group 2, the ankle between maxillary incisor and alveolar bone was (15.19±5.23)°, (18.51±6.62)°, respectively; there was no significant difference between male and female in each group, but there was significant difference between every 2 age groups in the angle between maxillary incisor and alveolar bone. CONCLUSIONS: The angle between maxillary incisor and alveolar bone is increasing with the increase of age, but no significant difference between male and female is detected. For patients with dental implantation in anterior area, CBCT should be taken to measure the angle between maxillary incisor and alveolar bone for aesthetic assessment, especially for old patients.

[Establishment and management of electronic appointment library for dental implant patients].

PURPOSE: To design an excel form which can prompt dental implant patient appointment through color change, which can scientifically manage implant EMR library through appropriate interlinkage and number. METHODS: An excel form based on operating system Windows XP was designed and software 2003 Microsoft excel was used, which was configured to change color with the passage of time by the use of command "conditional format". RESULTS: An excel form was designed. The color turned to red automatically on the day the patient underwent implant surgery. It turned to yellow when the patient recalled 2 weeks after the first operation, to green when the patient underwent secondary operation. It was designed to be gray when all the procedures of implant restoration was finished. In addition, we could know patients' main implant situation through directly opening his EMR when clicking on his name or number. CONCLUSIONS: Dentists can remind the implant patient appointment schedule through color change of an excel form, and can consult the implant patient EMR directly through interlinkage or number.

[Clinical assessment of acceptability of shade mismatch of infiltrated alumina ceramic crowns].

PURPOSE: To measure and evaluate the acceptability of shade mismatch of infiltrated alumina ceramic crowns directly in clinic. METHODS: Ten cases with restoration of hot casting alumina ceramic crown were collected in clinic. L*, a*, b*, C, H, ΔE values of hot casting alumina ceramic crowns and corresponding natural teeth in natural light were surveyed and calculated, then analyzed with CIE1976L*a*b* color system, digital photography and Photoshop CS2. All statistical analyses and calculations were completed in paired t test with SAS6.12 software package. RESULTS: In cervical 1/3 region, significant statistical difference in lightness, a*, hue angle parameter value between alumina all-ceramic crown and natural tooth (P<0.01) was found; in middle 1/3 region, significant difference in a*, b*, saturation parameter value (P<0.01) existed; in incisory 1/3 region, the parameters had no significant difference (P>0.05). To parameter ΔE, there was significant difference in every region, but it was in the acceptable range. CONCLUSIONS: The acceptability of shade mismatch is about 6 ΔE units, we can analyse the color difference between the restoration and natural teeth directly in clinic through symmetry of central incisor.

[3-D reconstruction of the maxillary central incisor by digital camera].

PURPOSE: To evaluate the role of digital camera in reconstruction of 3-D solid model of the maxillary central incisor. METHODS: Photographs of each section of the maxillary central incisor were taken with digital camera, then the 3-D model was reconstructed with photoshop software and 3DMAX software. RESULTS: The precise 3-D solid model of the maxillary central incisor was successfully reconstructed. CONCLUSIONS: 3-D reconstruction of the maxillary central incisor can be completely accomplished by dentists themselves.

[Non-invasive detection of metal casting defects using dental X ray machine].

PURPOSE: The purpose of this in vitro study is to find the best parameters in detecting the casting defects made of titanium, nickel-chromium and chromium-cobalt using dental X ray machine. METHODS: Casting sheets in different thickness (1.0 mm, 0.6 mm, 0.3 mm)were fabricated using of Ti, Ni-Cr and Cr-Co.Small pores on the surfaces were made with laser welder to simulate the internal porosity of the castings. Parameters of the dental X ray machine were adjusted to take films. The data were analyzed using SPSS12 software package for group t test. RESULTS: The thickness of Ti had no significant effect on the setting of the parameters of the dental X ray machine in detecting the defects of titanium castings (P>0.05), while the thickness of Ni-Cr and Cr-Co had significant effect on the setting of the parameters (P<0.05). CONCLUSION: Dental X ray machine can be used in detecting the defects of titanium casting sheets.