| The bracket placement is an important step during orthodontic treatment. In order to have an accurate bracket bonding, brackets-indirect-bonding technique is widely used these days. Further, indirect bonding technique can be categorized into the traditional and digital indirect bonding technologies. The traditional indirect bonding technique requires tedious work by laboratory technicians, which significantly hampers its clinical applications. During the development of information technology, the3D digital dental model becomes more and more popular due to its accuracy and convenience for storage and measurement. To date, the technique of positioning brackets in a digital model has become a hot topic in China. With the development of digital technology, digital indirect bonding technology is gradually applied in clinical orthodontics.However, several bracket placement protocols have been proposed. Angle recommended that the ideal position to place the bracket located at the center of the tooth labial surface. Andrews developed the straight-wire appliance and proposed that the brackets should be placed at the midpoint of the facial axis (FA) point. McLaughlin and Bennett suggested that the position of bracket should be based on the distance between the incisal edge and bracket groove which varied from person to person.. Ricketts and later Kalange recommended to find the vertical position of brackets according to the marginal ridges.The Objective Grading System (OGS) developed by the American Board of Orthodontics (ABO), named as ABO-OGS, is currently considered as an objective and reliable evaluation system for the therapeutic effects of orthodontic treatment. The evaluation system is based on a plaster model and X-ray panoramic radiographs. It can evaluate the outcome of orthodontic treatment accurately and objectively. The system includes8established occlusal criteria, including tooth alignment, vertical positioning of marginal ridges, buccolingual inclination of posterior teeth, occlusal relationship, occlusal contacts, overjet, interproximal contacts and root angulation. The first seven criteria are based on orthodontic models, whereas the eighth one, root angulation, is according to a panoramic radiograph. It scored from0-2points based on the abnormal degree of each criterion. The total score is the sum of the eight criteria. The lower of the total score indicated a better treatment. ABO-OGS scoring system can evaluate three levels of a model, which is considered as a useful index to evaluate the orthodontic treatment.At present, there are very few studies about the bracket positioning through a3D digital dental model or evaluating the orthodontic treatment effect using the ABO-OGS system. The goal of this study is to establish a three-dimensional digital model of reconstructed crowns, roots and jaws using a laser scanning and CBCT technology. Here, the full-sized DamonQ self-ligating brackets were drawn by the software. In addition, we compared the therapeutic effects of two different ways in locating the brackets:1) through combining the height of DamonQ self-ligating bracket and the long axis of tooth;2) bracket positioning system. We determined the effect of virtual orthodontic treatment based on three criteria, including alignment, marginal ridge height and root angulation, according to ABO-OGS grading system. We also discussed the feasibility of digital virtual positioning braces in clinical applications. As we know, whether the virtual brackets can mimic mouth precisely mainly depends on the consistency between the virtual brace position on the software and the exact position being transferred to a patient’s mouth. In this work, we investigated the difference between virtual and real bracket positions in the computer and plaster cast, respectively. This study will provide the basis for clinical application. My dissertation includes three chapters and described as followings.1. The establishment of three dimensional visualized digital model by the integration of the data of cone beam computer tomography images and laser scanning.The purpose of this study was to reconstruct crowns, roots and jaws with laser scanning and CBCT technology and establish a three-dimensional digital model. This study will lay the foundation to obtain the accurate position of the indirect-bonding-brackets.Total15invisible orthodontic patients were selected from the department of Guangdong Provincial stomatological hospital for this study. There are9cases of Angle class I malocclusion and6cases of Angle class II malocclusion. Among these patients,3were male,12were female. The age range is from23to38years old, with an average age of27.7years old. The patients were selected based on the following criteria:permanent dentition, complete dentition (28-32teeth), no extra teeth, no deformity teeth, no root canal treatment, no labial and buccal filling teeth, no teeth with excessive wear, no metal restorations. In addition, the patients whose CBCT image is not clear were excluded. The patients were informed and signed for the consent.The patients’ teeth were impressed with silicone rubber using twoa two-step methods. The silicone rubber models were sent to the Xi’an Henghui Technology Co. ltd. The data was acquired by using3D laser scanning, and then was process to obtain3D dataimage, saved in the STL format. All patients were scanned by using NewTom3G cone beam CT. By using lying projection, the scanned original volume data is transmitted to the computer, and digital processing was completedprocessed by usingwith a software image processing equipment program (NewTom NNT), then the DICOM image data with high resolution DICOM image data was were generated. According to bone density information, teeth data were extracted obtained from the CBCT, and then a single jaw STL was generated. Herein, we used the special software was used, andto match the STL laser scanning on image of the crown part was matched., Finally, the digital three-dimensional dental model included including the roots was established.Results:In this part, we obtained the three-dimensional models comprised of the roots, crown and jaws from15patients. These models are fine and smooth, presented clear anatomical details, from which we can clearly observe3D position of the crown and root. This study is of great significance to assess the effect of orthodontic treatment. To establish the3D digital dental model including the teeth root is essential for choosing the orthodontic treatment plan and evaluating the therapeutic effect. Based on the integrated model, we can clearly observe the situation of the crown and the arrangement of root, and then fully evaluate the spatial relationship among the crown, root and jaw. This study will provide the basis for formulating the therapeutic plan, and can avoid the improper orthodontic treatment, such as poor root, bone cracking, fenestration, root exposure as well as other serious consequences. This study also provides the basic information for the accurate positioning of the subsequent indirect-bonding brackets.2. A preliminary study on positioning of Damon Q self-ligating brackets on the digital integration model.According to the3D digital dental models from15patients, the full-sized DamonQ self-ligating brackets were drawn by the software. In addition, we compared the therapeutic effects of two different ways in locating the brackets:1) bracket location with root information;2) bracket height positioning system. We evaluated the effects of virtual orthodontic treatment based on three criteria, including alignment, marginal ridge height and root angulation, according to ABO-OGS grading system. We also discussed the feasibility of digital virtual positioning braces in clinical applications.Methods:1) First, we measured the clinical crown height with maxillary central incisor and mandibular central incisor in the gypsum model of15patients. We determined the height of bracket position according the following standards:the height of upper incisor and mandibular incisor is4.5mm and3.5mm, respectively.2) We determined the position of28teeth of15cases according to bracket location with root information.3) We determined the position of28teeth of15cases according to the height position method.4) The final status was generated by the software.5) Treatment:The treatment results were assessed with ABO-OGS. We compared the models that before and after orthodontic treatment with visual method in computer software. Herein, we evaluated the effects of virtual orthodontic treatment based on three criteria according to ABO-OGS grading system, including alignment, marginal ridge height and root angulation. The measurement interval of each case is2weeks, and every case measured3times. The results are the mean value of3measurements.6) Statistical analysis:This study is about teeth alignment, marginal ridge height, root parallelism of the three measurement indicators and composite indicators, using repeated measures ANOVA. Comparing the result before treatment and two different positioning methods after treatment. Results dissatisfaction football symmetry test results using the Greenhouse-Geisser correction. Software version SPSS19.0, set the significance level of0.05bits.Results:1)We obtained the final treatment status of all the patients by using the OrthoRx software.2) For the marginal ridge height, the mean value of the deduction points of was2.80±2.01before treatment according to ABO-OGS system. When we located the brackets with the method that combining height and long axis of tooth (referred to method one), the points became0.53±0.83after the virtual orthodontic treatment. When we positioned the brackets with the height position method (referred to method two), the points became0.27±0.46after virtual orthodontic treatment. According to analysis of variance for repeated measurement design, there were significant differences in the deduction points of marginal ridge height before and after treatment with method one and method two(F=22.691, P=0.000). In conclusion, the deduction points of marginal ridge height are significantly decreased after the treatment using these two methods. However, there were no statistics significance differences between method one and method two on the deduction points of marginal ridge height (P>0.05).3)For the teeth alignment, the mean value of the deduction points was10.80±5.06before the treatment based on ABO-OGS. When we located the brackets with method one, the deduction points became0.27±0.46after the treatment. In addition, the points became1.00±0.84after treatment with method two. According to analysis of variance for repeated measurement design, there were significant differences in the deduction points of alignment before and after treatment (F=67.144,P=0.000). The deduction points of alignment are significantly decreased after the treatment using these two kinds of positioning methods In addition, there were statistics significance differences between method one and method two on the deduction points of alignment (P<0.05).4) For the root parallelism of teeth, the mean of the deduction points was0.47±1.13before the treatment according to ABO-OSG. After virtual orthodontic treatment with method one, the deduction value became0.07±0.26. After the virtual orthodontic treatment with method two, the points became1.00±1.13. According to analysis of variance for repeated measurement design, compared method one with method two, there were statistics significance differences in the deduction points of root parallelism (F=5.971, P=0.007). But, there is no improvement on the deduction points of root parallelism with both methods (P>0.05), there were no statistics significance in the deduction points of root parallelism before and after treatment using both methods.5) For the deduction points of the three scoring components (including alignment, marginal ridge height and root angulation) of ABO-OGS, the mean value of the deduction points was14.07±7.15before the treatment. After virtual orthodontic treatment with method one, the deduction value became0.87±1.19. After the virtual orthodontic treatment with method two, the points became2.27±1.58. According to analysis of variance for repeated measurement design, there were significant differences in the deduction points of3scoring components before and after treatment using these two methods (F=54.818, P=0.000).The deduction points of3scoring components are significantly decreased after the treatment using these two kinds of positioning methods. Moreover, there were statistics significance differences in the deduction points of3scoring components in two methord (P<0.05).Conclusion:1) In the reconstruction of3D digital modes, we had achieved the effective therapeutic treatment with two different brackets positioning method using OrthoRx software.2) Method one, the bracket position method combining height with long axis of tooth, is more accurate, compared to method two. The research provides the experimental basis for bracket accurately in the mouth.3. The verification of consistency of bracket location in software and the actual location by indirect bonding transfer.In this part, we investigated the difference between software and the transition of model position of all brackets, as well as the difference between software and real position of all brackets. This study will provide the basis for clinical application.Methords:1) We selected15digital models according to the bracket position method which combined the height and long axis of tooth.2)The virtual bracket bonding position in the software was transferred to the hardware model.3) The line distance between software and hardware model in each bracket was measured with specific measurement tools.4) Making indirect bonding transfer tray.5) The brackets from the transfer tray were transferred to the original plaster models.6) The line distance between software and real position in each bracket was measured with specific measurement tools.7) Statistical analysis:The data of this study were presented as mean±standard deviation (s). The SPSS19software package was used for statistical analysis. First, each data was analyzed for normality test. Then, each set of data is analyzed for single sample t test, and the test value is0.1. The data of two groups were first analyzed with correlation coefficient test, and then compared by paired samples t test. The probabilities (P)<0.05was considered to be statistics significance, and P<0.01was considered to be significantly statistics significance.Results:1)The measurement results:The distance of bracket position between software and the transition of model position are as follows:A1:t=-15.863, P=0.000,95%confidence interval for the difference of a maximum is-0.089; A2:t=-13.909, P=0.000,95%confidence interval for the difference of a maximum is-0.070; A3:t=-14.414, P=0.000,95%confidence interval for the difference of a maximum is-0.078; A4:t=-19.526, P=0.000,95%confidence interval for the difference of a maximum is-0.112; A5:t=-16.950, P=0.000,95%confidence interval for the difference of a maximum is-0.101; B1:t=-9.322, P=0.001,95%confidence interval for the difference of a maximum is-0.065; B2:t=-10.428, P=0.000,95%confidence interval for the difference of a maximum is-0.066; B3:t=-15.144, P=0.000,95%confidence interval for the difference of a maximum is-0.093; B4:t=-21.046, P=0.000,95%confidence interval for the difference of a maximum is-0.108; B5:t=-33.444, P=0.000,95%confidence interval for the difference of a maximum is -0.121; C1:t=-16.595, P=0.000,95%confidence interval for the difference of a maximum is-0.090; C2:t=-16.820, P=0.000,95%confidence interval for the difference of a maximum is-0.098; C3:t=-15.272, P=0.000,95%confidence interval for the difference of a maximum is-0.094; C4:t=-18.776, P=0.000595%confidence interval for the difference of a maximum is-0.094; C5:t=-18.403, P=0.000,95%confidence interval for the difference of a maximum is-0.101;Dl:t=-19.074, P=0.000,95%confidence interval for the difference of a maximum is-0.101; D2:t=-16.895, P=0.000,95%confidence interval for the difference of a maximum is-0.089;D3:t=-13.260, P=0.000,95%confidence interval for the difference of a maximum is-0.094;D4:t=-15.293, P=0.000,95%confidence interval for the difference of amaximum is-0.083; D5:t=-11.630, P=0.000,95%confidence interval for the difference of a maximum is-0.067. So there were significant differences between test line and the value of0.20mm, all the test values are less than0.20mm, so these can be considered a virtual bracket position is consistent with the hardware position.2) The measurement results:The distance of bracket position between software and actual position are as follows:Al:t=-7.159, P=0.000,95%confidence interval for the difference of a maximum is-0.057; A2:t=-6.702, P=0.000,95%confidence interval for the difference of a maximum is-0.045; A3:t=-8.983, P=0.000,95%confidence interval for the difference of a maximum is-0.073; A4:t=-8.582, P=0.000,95%confidence interval for the difference of a maximum is-0.069; A5:t=-9.133, P=0.000,95%confidence interval for the difference of a maximum is-0.072; B1:t=-10.582, P=0.001,95%confidence interval for the difference of a maximum is-0.075; B2:t=-12.642, P=0.000,95%confidence interval for the difference of a maximum is-0.081; B3:t=-6.327, P=0.000,95%confidence interval for the difference of a maximum is-0.043; B4:t=-10.452, P=0.000,95%confidence interval for the difference of a maximum is-0.077; B5:t=-15.792, P=0.000,95%confidence interval for the difference of a maximum is-0.087; C1:t=-8.601, P=0.000,95%confidence interval for the difference of a maximum is-0.070; C2:t=-12.166, P=0.000,95%confidence interval for the difference of a maximum is-0.082; C3:t=-7.412, P=0.000,95%confidence interval for the difference of a maximum is-0.051; C4:t=-5.405, P=0.000,95%confidence interval for the difference of a maximum is-0.038; C5:t=-8.724, P=0.000,95%confidence interval for the difference of a maximum is-0.047; D1:t=-8.680, P=0.000,95%confidence interval for the difference of a maximum is-0.075; D2:t=-9.552, P=0.000,95%confidence interval for the difference of a maximum is-0.070; D3:t=-9.970, P=0.000,95%confidence interval for the difference of a maximum is-0.068; D4:t=-7.758, P=0.000,95%confidence interval for the difference of a maximum is-0.058; D5:t=-12.393, P=0.000,95%confidence interval for the difference of a maximum is-0.084. So there were significant differences between test line and the value of0.20mm, all the test values are less than0.20mm, so these can be considered a virtual bracket position is consistent with the actual position.3) We compared the line distance between hardware and real position by paired t test. The results are as follows:Al: t=1.669, P=0.102; A2:1=1.520, P=0.136; A3:t=-0.281, P=0.780; A4:1=3.062, P=0.004; A5:1=1.499, P=0.141; B1:t=-0.736, P=0.465; B2:1=4.556, P=0.127; B3: t=3.877, P=0.000; B4:1=2.842, P=0.007; B5:1=3.593, P=0.001; C1:1=0.713, P=0.480; C2:t=1.409, P=0.166; C3:t=3.108, P=0.003; C4:t=3.569, P=0.001; C5: t=6.419, P=0.000; D1:1=1.171, P=0.248; D2:t=1.020, P=0.313; D3:1=1.152, P=0.256; D4:1=1.510, P=0.138; D5:t=4.957, P=0.057. The results showed that there was no significant difference among these teeth A1, A2, A3, A5, B1, B2, C1, C2, D1, D2, D3, D4, D5(P>0.05), which suggested that the hardware position and real position were almost consistent. However, there was significant difference among these teethA4, B3, B4, B5, C3, C4, C5(P<0.05).Conclusion:1) In the process of brackets transfered from software position to hardware position, we measured the line distance between software position and hardware position of brackets. The difference of most brackets is close to0.2mm, so software position and hardware position of brackets is considered consistently.2) In the process of brackets transfered from software position to real position, we measured the line distance between software position and real position of brackets. The difference of most brackets is close to0.2mm, so software position and actual position of brackets is considered consistently. |
PDF Full Text Request