Variation of orthodontic treatment decision-making based on dental model type: A systematic review

Objective:To determine in which clinical scenarios digital models are valid as replacements for plaster models during orthodontic treatment decision-making process and treatment planning.Materials and Methods:An attempt to identify all pertinent published information was made. Retained articles were those where a decision-making process leading to differential orthodontic treatment plans based on either method were compared. The search was tailored for PubMed and adapted for EMBASE, MEDLINE, the Cochrane Library, LILACS, and Web of Science. A partial grey literature search was conducted through Google Scholar. References lists of the included articles were screened for potential relevant studies. The methodology of selected studies was evaluated using the Quality Assessment Tool for Diagnostic Accuracy Studies (QUADAS).Results:Only two studies were finally selected for the qualitative and quantitative synthesis. QUADAS results scores from selected studies ranged from 61% to 83% of 11 items evaluated. In one, the overall treatment plan regarding orthognathic surgery for Class II malocclusion changed in 13% to 22% of the cases. In the other one, 6% of the orthodontic treatment plans changed.Conclusion:Digital models could be used to replace plaster models in Class II malocclusion treatment planning.     

三维数字化技术在口腔正畸学中的应用

工业发展和软件的开发使三维数字化技术逐渐应用于口腔正畸学领域.牙列、气道、下颌运动等多方面都可以通过建模实现数字化,并用于协助临床诊疗.牙颌是正畸医生关注的中心,模型获取方式由传统石膏向数字化转变.通过不同方法采集数据重建模型,应用于正畸治疗的分析诊断、排牙实验、辅助设计个性化托槽和隐形矫治器.将正畸逐步发展成为数字化分析、诊断和治疗的全新模式,提高患者的治疗效果.本文就数字化在口腔正畸中的应用作一综述.     

Photographs of dental casts or digital models: rating dental arch relationships in bilateral cleft lip and palate

Yardsticks have been developed to measure dental arch relations in cleft lip and palate (CLP) patients as diagnostic proxies for the underlying skeletal relationship. Travelling with plaster casts to compare results between CLP centres is inefficient so the aim of this study was to investigate the reliability of using digital models or photographs of dental casts instead of plaster casts for rating dental arch relationships in children with complete bilateral cleft lip and palate (CBCLP). Dental casts of children with CBCLP (n=20) were included. Plaster casts, digital models and photographs of the plaster casts were available for all the children at 6, 9, and 12 years of age. All three record formats were scored using the bilateral cleft lip and palate (BCLP) yardstick by four observers in random order. No significant differences were found for the BCLP yardstick scores among the three formats. The interobserver weighted kappa scores were between 0.672 and 0.934. Comparison between the formats per observer resulted in weighted kappa scores between 0.692 and 0.885. It is concluded that digital models and photographs of dental casts can be used for rating dental arch relationships in patients with CBCLP. These formats are a reliable alternative for BCLP yardstick assessments on conventional plaster casts.     

Accuracy of three-dimensional dental resin models created by fused deposition modeling,stereolithography, and Polyjet prototype technologies: A comparative study

Objectives: The aim of this study was to assess the dimensional accuracy of fused deposition modeling (FDM)–, Polyjet-, and stereolithography (SLA)–produced models by comparing them to traditional plaster casts.Materials andMethods: A total of 12 maxillary and mandibular posttreatment orthodontic plaster casts were selected from the archives of the Orthodontic Department at the Indiana University School of Dentistry. Plaster models were scanned, saved as stereolithography files, and printed as physical models using three different three-dimensional (3D) printers: Makerbot Replicator (FDM), 3D Systems SLA 6000 (SLA), and Objet Eden500V (Polyjet). A digital caliper was used to obtain measurements on the original plaster models as well as on the printed resin models.Results: Comparison between the 3D printed models and the plaster casts showed no statistically significant differences in most of the parameters. However, FDM was significantly higher on average than were plaster casts in maxillary left mixed plane (MxL-MP) and mandibular intermolar width (Md-IMW). Polyjet was significantly higher on average than were plaster casts in maxillary intercanine width (Mx-ICW), mandibular intercanine width (Md-ICW), and mandibular left mixed plane (MdL-MP). Polyjet was significantly lower on average than were plaster casts in maxillary right vertical plane (MxR-vertical), maxillary left vertical plane (MxL-vertical), mandibular right anteroposterior plane (MdR-AP), mandibular right vertical plane (MdR-vertical), and mandibular left vertical plane (MdL-vertical). SLA was significantly higher on average than were plaster casts in MxL-MP, Md-ICW, and overbite. SLA was significantly lower on average than were plaster casts in MdR-vertical and MdL-vertical.Conclusions: Dental models reconstructed by FDM technology had the fewest dimensional measurement differences compared to plaster models.     

Validity and reliability of digital diagnostic measurements on digital three-dimensional dental models

Digital three-dimensional dental models are widely used for orthodontic diagnosis. The aim of this clinical study was to assess the validity and reliability of digital diagnostic measurements on digital three-dimensional dental models. Two types of digital three-dimensional dental models and a plaster dental model were made of 10 volunteers. Digital measurements of the tooth width were compared with the physical measurements of the plaster models. None of the digital diagnostic measurements appeared to differ significantly from the physical measurements.     

数字化效果模拟器在口腔正畸临床教学中的应用效果评估

目的评估数字化效果模拟器在口腔正畸临床教学中的应用效果。 方法选取2020—2021年于中山大学附属口腔医院正畸科就诊的安氏Ⅰ类、安氏Ⅱ类和安氏Ⅲ类错畸形病例共6个，完善问诊、临床检查和X线片检查后，提供相应的石膏模型和数字化模型。中山大学光华口腔医学院口腔正畸学专业的2018 ~ 2021级研究生28人通过分层随机抽样法分为两组（每组14人），分别进行传统的石膏模型排牙预测（A组）和数字化效果模拟器预测（B组），并完成正畸诊断和治疗计划。由具有硕士生导师资格的3位教师对其诊断和治疗计划进行评估，同时讲授其依据。两组学生分别对传统石膏排牙预测和数字化效果模拟器预测过程进行评价。 结果在"制定方案主动性"和"考虑牙移动细节"方面，B组学生得分高于A组，差异具有统计学意义（P<0.001）。相比于A组，B组中更多学生认为数字化模拟器可提高学习兴趣（A组78.57%、B组100%）、加深对诊断与治疗计划的理解（A组75.00%、B组89.28%）和考虑更多三维牙移动（A组64.28%、B组75.00%）。在教师评价中，B组在治疗计划讲授过程得分高于A组（P<0.001）。 结论数字化效果模拟器可锻炼学生的临床思维能力，提高口腔正畸诊断与治疗计划的制定的教学效果。     

Logistics in digital orthodontic models

Time has come for the replacement of traditional plaster models by digital ones. Digital technology now fulfills our diagnostic and medico-legal purposes. The American Board of Orthodontics (ABO) recognizes the value of digital models. The technology is available and affordable. The advantages of digital models surpass the advantages over plaster models. The purpose of this article is to expose the reader to the logistics of digital models and let you ask the pertinent question: is it time for me to go digital?     

A comparison of patient experience,chair-side time,accuracy of dental arch measurements and costs of acquisition of dental models

Objective:To compare patient experience, chairside time, dental arch distances, and costs of dental models derived from intraoral scans and alginate impressions in pre-orthodontic children and young adolescents.Materials and Methods:Fifty-nine children and young adolescents (9–15 years, mean: 12.70 years) had an intraoral scan and an alginate impression prior to orthodontic treatment. During the procedures, chairside time was registered in minutes and patient experience was assessed by a Visual Analogue Scale questionnaire. Four maxillary dental arch distances were measured on digital models, on plaster casts, and directly in the mouth (intraoral). The cost of each procedure was presented graphically. Differences between the two procedures were tested by paired t-test and general linear model.Results:Patient experience was statistically better during intraoral scan compared with alginate impression regarding comfort, gag reflex, breathing, smell/sound, taste/vibration, and all statements concerning anxiety (P < .05). No significant difference in chairside time between the two procedures was found. No statistically significant differences in dental arch distances between digital models and plaster casts were found, but dental arch distances measured intraorally differed significantly from both digital models and plaster casts (P < .05). Cost calculation showed that the digital procedure was 10.7 times more expensive than the conventional procedure initially and, that after 3.6 years, the two procedures were equal in cost.Conclusions:Children preferred intraoral scan rather than alginate impression. Chairside time was equal for the two procedures as were the measurements of maxillary dental arch distances. The two procedures were equal in cost at 3.6 years.     

Intra‐arch dimensional measurement validity of laser‐scanned digital dental models compared with the original plaster models: a systematic review

A systematic review was undertaken to evaluate the validity of intra‐arch dimensional measurements made from laser‐scanned digital dental models in comparison with measurements directly obtained from the original plaster casts (gold standard). Finally included articles were only those reporting studies that compared measurements from digital models produced from laser scanning against their plaster models. Measurements from the original plaster models should have been made using a manual or digital caliper (gold standard). Articles that used scans from impressions or digital photographs were discarded. Detailed individual search strategies for Cochrane, EMBASE, MEDLINE, PubMed, and LILACS were developed. The references cited in the selected articles were also checked for any references that could have been missed in the electronic database searches. A partial gray literature search was undertaken using Google Scholar. The methodology of selected studies was evaluated using the 14‐item quality assessment tool for diagnostic accuracy studies (QUADAS). Only 16 studies were finally included for the qualitative/quantitative synthesis. The selected studies consistently agree that the validity of measurements obtained after using a laser scanner from plaster models is similar to direct measurements. Any stated differences would be unlikely clinically relevant. There is consistent scientific evidence to support the validity of measurements from digital dental models in comparison with intra‐arch dimensional measurements directly obtained from them.     

Evaluation of the accuracy of digital model analysis for the American Board of Orthodontics objective grading system for dental casts.

INTRODUCTION: In 1999, after 3 years of field testing, the American Board of Orthodontics (ABO) implemented a grading system for posttreatment orthodontic models and panoramic radiographs, to make the phase III examination both fair and objective. In the ABO's objective grading system, 7 occlusal criteria (tooth alignment, vertical positioning of marginal ridges, buccolingual inclination of posterior teeth, occlusal relationship, occlusal contacts, overjet, and interproximal contacts) are measured on plaster models to assess a patient's final occlusion. To date, no study has evaluated the ABO grading system for use on digital models. The purpose of this study was to determine whether digital models can be used with reasonable accuracy and reliability for assessing patients' final occlusions. METHODS: Plaster and digital (OrthoCAD, Cadent Inc, Carlstadt, NJ) posttreatment models of 24 patients were gathered from the postgraduate orthodontic clinic at Columbia University School of Dental and Oral Surgery. The plaster models were scored by using the ABO measuring gauge and the 7 criteria of the ABO grading system. A second analysis was done on the digital models. To determine interexaminer error, a fourth-year dental student at Columbia University served as a second examiner and repeated all the analyses. RESULTS: The means of the total score and those for marginal ridges, occlusal contacts, occlusal relationships, overjet, and interproximal contacts were not significantly different between plaster and digital models. However, the means for alignment and buccolingual inclination were significantly different. In addition, the scorings of 2 examiners differed for the 2 methods. CONCLUSIONS: This finding suggests that alignment and buccolingual inclination should be reevaluated with both methods, and adequate calibration of the examiners is essential to achieve repeatability in both methods. Digital models might be acceptable for use in the ABO model examination.     

Long-term stability of the leveling of the curve of Spee.

The aim of the study was to investigate whether the orthodontic leveling of the curve of Spee is a treatment procedure with a stable result on a long-term basis. Measurements were made on the plaster casts of 149 orthodontically treated patients (57 males and 92 females). The mean age before treatment was 12.8 years (range, 8-25 years). Study casts were taken before treatment (T1), at the completion of orthodontic therapy (T2), and 6.7 years (mean) posttreatment (T3). Inclusion criteria were no extractions, all Angle classifications except Class III malocclusions, and all permanent teeth fully erupted except second and third molars. The curve of Spee and the irregularity index were measured on standardized digital photographs of the casts. Overjet and overbite were assessed with a ruler. Changes in the curve of Spee were correlated with changes in irregularity index, overjet, and overbite from T1 to T3. The following results were noted: (1) leveling of the curve of Spee is a relatively stable treatment procedure compared with a return of incisor crowding and deepening of the bite; (2) neither the initial depth of the curve of Spee nor the initial irregularity index is an indicator for the amount of relapse; (3) the amount of leveling is not correlated with the relapse of the 4 tested parameters (curve of Spee, irregularity index, overjet, and overbite); and (4) there is a mild correlation between the relapse of the curve of Spee and the relapse of the irregularity index, overjet, and overbite. According to the results of the study, leveling the curve of Spee during orthodontic treatment seems to be very stable on a long-term basis; it was weakly correlated with the other variables tested.     

Three-dimensional imaging: The caseWestern Reserve University method

The goal of this project was to create a lifelike digital record of human dentofacial morphology. Traditionally, orthodontists have relied on a lateral and sometimes a frontal cephalometric radiograph, three facial and three intraoral photographs, and upper and lower dental study casts to capture the dentofacial morphology of their patients. Creating a unified digital record of dentofacial morphology requires all records to share the same space. Therefore, to be lifelike, all records should eventually be positioned within a computer (on-screen) representation of the three-dimensional (3D) space of the patient's head. This requirement necessitated that radiographic and facial surface morphology be rendered in 3D and that 3D study casts be converted to digital format. This article describes the Case Western Reserve University method for (1) rendering the lateral and frontal biorthogonal cephalogram pairs in 3D; (2) capturing the 3D surface of the human face; (3) converting the plaster dental cast data to a 3D digital record; and (4) integrating lateral and frontal radiographs, facial surface scans, and digital study models into a single 3D patient record. In addition, the creation of standard 3D cephalometric wireframes using the Bolton Standard subjects is described. Finally, two case reports are presented to show the use of this 3D digital record to analyze craniofacial hard and soft tissue changes brought about by Le Fort I maxillary advancement surgery. In the case reports, traditional cephalometric superimpositions are compared with 3D color-coded surface superimpositions of the preoperative and postoperative facial images. The advantages and disadvantages of this digital outcomes assessment method are discussed in this presentation of a model for the future 3D orthodontic patient record.     

锥形束CT数字化牙颌模型测量的可靠性和准确性评价

目的:研究应用锥形束CT(CBCT)获取数字化牙颌模型测量的可靠性。方法:选择正畸治疗患者的石膏模型40副,采用CBCT扫描石膏牙颌模型,对其进行测量,并与手工测得的结果进行一致性相关系数(concordance correlationcoefficient,CCC)和均数差(mean difference,MD)比较。结果:所有测量项目的CCC在0.847~0.993之间,大部分测量项目的均数差小于0.25mm,但CFF6、PWF5和PWM6的均数差分别为0.34mm、0.63mm和1.49mm。结论:锥形束CT数字化牙颌模型测量的可靠性好,精确度高。牙尖测量的准确性最高,中央窝次之,腭侧龈缘最低点的测量准确性最低。     

Evaluation of the validity of tooth size and arch width measurements using conventional and three-dimensional virtual orthodontic models

Measurements and different analyses of dental casts are essential for precise diagnosis of an orthodontic case. At present, virtual computerized models, such as OrthoCAD, are available for clinicians, supplemented by dedicated software for performing needed measurements on them. The purpose of this study was to test the accuracy of measuring casts with the aid of calipers or OrthoCAD and compare these two techniques. Twenty setups using artificial teeth corresponding to various malocclusions were created. Impressions were taken of them, providing 20 plaster and 20 virtual orthodontic models. Measurements of mesiodistal tooth dimension as well as intercanine and intermolar width were made on both. Additionally, values of tooth size were calculated from the isolated artificial teeth removed from the setups and of arch width from the existing setups. The resulting values were compared by the use of nonparametric statistics, and methods' errors were also calculated. Results showed the methods being highly valid and reproducible for both tooth size and arch width. For the tested clinically applicable methods, measurement with digital calipers on plaster models showed the highest accuracy and reproducibility, closely followed by OrthoCAD. Digital calipers seem to be a more suitable instrument for scientific work. However, OrthoCAD's accuracy is clinically acceptable, and most likely, considering its present advantages and future possibilities, the examined or an equivalent 3D virtual models' procedure would become the standard for orthodontic clinical use.     

The influence of cephalometrics on orthodontic treatment planning

Since its introduction, cephalometrics, i.e. cephalometric radiography and analysis, has been used for orthodontic treatment planning. However, the effectiveness of this diagnostic method remains questionable. A randomized crossover study was designed to assess the influence of cephalometrics in orthodontic treatment planning of individual patients. Diagnostic records of 48 subjects (24 males and 24 females aged 11-14 years) were divided in two stratified groups and assigned to one of two combinations: A, dental casts only, and B, dental casts, cephalometric radiographs, and analysis. The records were presented to 10 orthodontic postgraduates and four orthodontists for formulation of orthodontic treatment plans containing a dichotomous decision regarding the use of a functional appliance (FUNC), rapid maxillary expansion (RME), and extraction (EXTR). The combination of FUNC + RME + EXTR was used as the basis of the outcome measure. Agreement on orthodontic treatment planning using all possible comparisons of diagnostic records of individual patients (AB, AA, and BB) was assessed and overall proportions of agreement (OPA) were calculated for orthodontic postgraduates and orthodontists separately. Median OPA were 0.60 (AB), 0.65 (AA), and 0.60 (BB) for orthodontic postgraduates and 0.50 (AB), 0.75 (AA), and 0.50 (BB) for orthodontists. Irrespective of the level of experience, neither consistency of orthodontic treatment planning between both combinations of diagnostic records showed a statistically significant difference (P > 0.05) using Wilcoxon signed rank test nor did consistencies and agreement of orthodontic treatment planning after the addition of cephalometrics. It appears that cephalometrics are not required for orthodontic treatment planning, as they did not influence treatment decisions.     

数字化牙模三维重建及快速制造技术研究

目的解决正畸矫治牙模的存放问题并对正畸过程进行有效指导。方法由i-CAT锥形束CT（cone beam computed tomography,CBCT）扫描获得数据,采用Mimics软件重建牙颌三维实体模型,Magics软件进行数据修补,选区激光烧结快速成型蜡质牙颌模型。结果选用优化的工艺参数,成型了良好表面质量的上下牙颌蜡质模型,整个快速成型过程用时5～6h。结论采用该技术保存CT数据,根据牙科正畸或手术的需要随时快速制造蜡模,可以省去保存石膏模型的不便和麻烦。     

Three-dimensional imaging of orthodontic models: a pilot study

Computer-based digital orthodontic models have been developed that have the potential to replace dental casts. The aim of this study was to examine the accuracy and reproducibility of measurements made on digital models. Ten sets of orthodontic study models were scanned using the Arius3D Foundation System and three-dimensional (3D) images were produced by computer software. Two examiners individually measured 11 parameters on the conventional casts and the digital models on two occasions. The parameters included mesio-distal crown diameter, intercanine and intermolar width, arch length, overjet, and incisor crown height. The measurement techniques were compared using paired t-tests, the coefficient of reliability, and by calculating mean values and the difference between methods. When comparing measurements made on digital models with those on dental casts, systematic errors were detected for five of the 11 parameters at the 10 per cent level. Random errors were a cause of concern for measurements of three parameters. The most accurate and reproducible measurements were lower intercanine width (mean difference between measurements 0.05 +/- 0.32 mm) and overjet (mean difference 0.07 +/- 0.33 mm). Most parameters on the digital models can be reliably measured, and digital models can potentially eliminate the requirement for the production and storage of dental casts, but this will depend on cost.     

A critical comparison of three methods for measuring dental models

A critical comparison of three methods for measuring distances between various fiducial points on orthodontic plaster casts is presented. The first method consisted of using a vernier caliper by which direct measurements (Dv) of the distances were recorded. The second method consisted of measuring the same casts using a reflex metrograph (Dm), where the co-ordinates of the points relative to two axes were recorded and the distances between various points were calculated. In the third method, reflection holograms of the casts were made, and the same distances were measured on the holographic images (Dh) using the reflex metrograph. The Wilcoxon sign rank test indicated no significant differences (p greater than 0.1) between measurements made by the various techniques. The means of the different distances scored varied within less than 0.5 mm (Dv-Dh), 0.5mm (Dv-Dm) and 0.2mm Dm-Dh). This study indicated that holograms can provide sufficiently accurate representations of orthodontic study models. Their retention as case records may solve the problem of the storage of orthodontic plaster casts.     

Evaluation of the use of digital study models in postgraduate orthodontic programs in the United States and Canada

Objective:To investigate the extent, experience, and trends associated with digital model use, as well as the advantages of using a particular study model type (digital or plaster) in postgraduate orthodontic programs in the United States and Canada.Materials and Methods:An electronic survey consisting of 14 questions was sent to 72 program directors or chairpersons of accredited orthodontic postgraduate programs in the United States and Canada.Results:Fifty-one responded for a 71% response rate. Sixty-five percent of the schools use plaster study models compared with 35% that use digital models. The most common advantages of plaster models were a three-dimensional feel and the ability for them to be mounted on an articulator. The most common advantages of digital models were the ease of storage and retrieval, and the residents'' exposure to new technology. About one third of the plaster model users reported that they wanted to switch to digital models in the future, with 12% planning to do so within 1 year.Conclusions:Based on our study, 35% of accredited orthodontic postgraduate programs in the United States and Canada are using digital study models in most cases treated in their programs, and the trend is for increased digital model use in the future.