A Feasible Study On Measuring Normal Teeth Morphology Data By Panoramic Radiography X-ray And Cone Beam CT

To form the whole dentition digital model and establish a normal teeth morphology database will give a great impetus to dental clinical practice, scientific research and teaching. The use of imageology methods instead of traditional manual methods to measure normal teeth morphology data has become a trend. The imageology methods can be used to measure the human whole dentition in vivo. With the development of imageology and computer-aided design, these methods are greatly improved, for instance, some can provide the thickness of tooth enamel and clear marrow morphology images, some can reconstruct the whole dentition three-dimensional morphology by using special software and so on. All these methods have greatly improved the accuracy of the data measurements. Objective:The purpose of this study was to investigate the feasibility of measuring normal teeth morphology data by Panoramic Radiography X-ray and Cone Beam CT (CBCT) system.Methods:1. The whole dentition plaster casts of the 10 normal adults (6 males, 4 females, aged from 24 to 27) were prepared, then the dental crown widths and dental crown thicknesses were measured by vernier caliper. The measurements were taken twice at an interval of two weeks. These data were analyzed by Paired T-test in the SPSS software package in order to evaluate the accuracy and repeatability of the measurements.2. To prepare jaw pads in which metal balls with standard size were embedded. The volunteers were asked to put these jaw pads into their mouths and their whole dentition were scanned by Panoramic Radiography X-ray. The images’distortions were corrected according to the change of diameter of the metal balls in the software. Then the dental crown width and tooth length were measured. The measurements were taken twice at an interval of two weeks. These data, together with the data taken by vernier caliper were analyzed by Paired T-test in the SPSS software package in order to evaluate the repeatability and accuracy of the measurements take by Panoramic Radiography.3. The whole dentition of the volunteers were scanned by CBCT, then the dental crown width, dental crown thicknesses and tooth length were measured by the CBCT official authorized software. The measurements were taken twice at an interval of two weeks. These data, together with the data taken by vernier caliper were analyzed by Paired T-test in the SPSS software package in order to evaluate the repeatability and accuracy of the measurements take by CBCT system.Results:1. The P values of upper jaw dental crown widths ranged from 0.11 to 0.91, upper jaw dental crown thicknesses ranged from 0.09 to 0.78, lower jaw dental crown widths ranged from 0.29 to 0.83 and lower jaw dental crown thicknesses ranged from 0.12 to 0.76 between the measurements performed at two different times by vernier caliper. It showed that the results were repeatable, and the experimenter could take an accurate identification and measurement of the markers at different times.2. The P values of upper jaw dental crown widths ranged from 0.11 to 0.78, upper jaw tooth lengths ranged from 0.11 to 1.00, lower jaw dental crown widths ranged from 0.22 to 0.89 and lower jaw tooth lengths ranged from 0.23 to 0.89 between the measurements performed at two different times by Panoramic Radiography X-ray system. It showed that the results were repeatable, and the experimenter could take an accurate identification and measurement of the markers at different times.The P values of upper jaw dental crown widths ranged from 0.00 to 0.89 and lower jaw dental crown widths ranged from 0.00 to 0.79 between the means of twice measurements by Panoramic Radiography X-ray system and the means of twice measurements by vernier caliper. No significant difference was observed in 16 pairs, meanwhile, significant difference was observed in the other 12 pairs (P≤0.05). The P values of anterior teeth and premolar teeth were stabler than molar teeth.3. The P values of upper jaw dental crown widths ranged from 0.07 to 0.97, upper jaw dental crown thicknesses ranged from 0.07 to 0.83, upper jaw tooth lengths ranged from 0.06 to 0.98, lower jaw dental crown widths ranged from 0.08 to 0.97, lower jaw dental crown thicknesses ranged from 0.08 to 0.87 and lower jaw tooth lengths ranged from 0.07 to 0.98 between the measurements performed at two different times by CBCT system. It showed that the results were repeatable, and the experimenter could take an accurate identification and measurement of the markers at different times.The P values of upper jaw dental crown widths ranged from 0.06 to 0.91, upper jaw dental crown thicknesses ranged from 0.14 to 0.71, lower jaw dental crown widths ranged from 0.09 to 0.89 and lower jaw dental crown thicknesses ranged from 0.07 to 0.98 between the means of twice measurements by CBCT and the means of twice measurements by vernier caliper. No significant difference was observed between the two methods.Conclusions:1. The measurements of normal teeth morphology data by vernier caliper, Panoramic Radiography X-ray and the CBCT system are stable and repeatable.2. The data taken by Panoramic Radiography X-ray system after correcting the distortions were still different from the data taken by vernier caliper, so the system could not be used for in vivo measurement of the whole dentition dental morphological data.3. The measurement of normal teeth morphology data by the CBCT system was stable and reliable, and the system could be used for in vivo measurement of the whole dentition dental morphological data.