[Comparison of the diagnostic validity and accuracy of the spiral tomography and spiral C.T. scan in maxillary implant assessment]

The accuracy and validity of CT scan images have been established by various investigators. However, there are controversies about the accuracy and validity of tomography techniques. The purpose of this study was to compare the accuracy and validity of diagnostic measurements made out of spiral tomography and spiral CT of human maxilla. Eight partially or fully edentulous dry human maxillae were used in this invitro investigation. A total of 50 edentulous areas were identified as potential implant sites. These locations were composed of 8 sites in midline, 14 in canine, 15 in premolar and 13 sites in molar areas. The spiral tomographies as well as spiral CTs were taken for the selected sites. The following bone parameters were measured in each maxilla: I] Vertical distance between the surface of alveolar bone and floor of nasal cavity or maxillary sinuses [Height]. II] Buccopalatal alveolar ridge distance at the mid-height section[Width]. Tomography measurements were compared with that of CT images in order to determine the measurements precision. To investigate the validity, the method of Inter-device Inter-observer and test of Intra-class Correlation Coefficient of One-Way Random Effects model was applied. Only 6 out of 100 measurements of tomography showed more than 1mm difference with CT images. The accuracy of tomograms in measuring height and width of alveolar bone was 96% and 92% respectively. This accuracy was 100% in midline, 93.3% in canine, 86.7% in premolar and 100% in molar area. The mean difference was 0.66mm between measurements of these two techniques. The reliability of tomograms was 96%. This investigation demonstrated that spiral tomography is highly accurate in cross sectional imaging of the jaw bones. The validity and reliability of spiral tomography technique is good and acceptable .Therefore, we can use tomography for jaw bones imaging in potential implant cases with high level of confidence

effect of two disinfectant solutions on dimensional changes of impression materials

The purpose of this invitro study was to investigate the effect of disinfectants on dimensional changes of Speedex impression material. Thirty impressions were taken by Speedex impression material from laboratory stainless steel model. 20 impressions were disinfected, 10 using%5.25 sodium hypochlorite and using 2% Acid glutaraldehyde for 10 minutes. And 10 impressions served as non-disinfected as control group. Impressions were then rinsed under the cold water and stored in room temperature for 20 minutes in disinfected group and 30 minutes in nondisinfected group. Casts were made using type IV gypsum. The height and diameters of dies and the distance between the dies were measured in the three groups. Statistical analysis of the data was done using ANOVA and t- test. The height of the die in the sodium hypochlorite group increased and in the glutaraldehyde group decreased vs control group. The diameter of the die in both sodium chlorite and glutaradehyde group had some increase vs control group. The distance between the dies decreased in both groups vs control group. The differences were not significant. There was no significant difference in dimensional changes between disinfected and non-desinfected