Fig 3 - uploaded by Ernest Lam
Content may be subject to copyright.
Source publication
The purposes of this study were to examine the effect of potentially common patient positioning errors in panoramic radiography on imaged mesiodistal tooth angulations and to compare these results with the imaged mesiodistal tooth angulations present at an idealized head position. A human skull served as the matrix into which a constructed typodont...
Contexts in source publication
Context 1
... coordinate-measuring machine (CMM; HGC Model; Starrett Corp, Gardner, Mass) was used with custom-designed software (Mechanical Engineering, University of Alberta) to determine the true mesiodistal angulation of each typodont tooth relative to the reference archwire (Fig 3). The CMM provided X, Y, and Z coordinate values for each digitized point from an established origin. ...
Context 2
... maxillary and mandibular study typodonts were then digitized separately with varying orientations of the machine's external probes (Fig 3). The typodont was attached to a surveyor table to prevent its movement and permit access to the occlusal/apical steel reference balls and reference archwire. ...
Similar publications
The objective of this study was to develop a new practical method to reconstruct a high-quality panoramic image in which radiographers would be free from the onerous task of correctly locating the patient's jaws within the image layer of the panoramic unit. In addition, dentists would be able to freely select any panoramic plane to be reconstructed...
Citations
... The most appropriate angle of the occlusal line in a panoramic X-ray image has not been defined, and thoroughly evaluating and comparing the quality of these images is difficult. In addition, these radiographs are often acquired in series for a patient and compared over time; therefore, image reproducibility is essential [14,15]. Therefore, we evaluated the effect of slight positioning errors on the image quality using a phantom and crosscorrelation coefficients of the occlusal plane profile, left/ right angle difference, PSNR, and vector displacement of the images [5,12]. ...
Background
A panoramic X-ray image is generally considered optimal when the occlusal plane is slightly arched, presenting with a gentle curve. However, the ideal angle of the occlusal plane has not been determined. This study provides a simple evaluation index for panoramic X-ray image quality, built using various image and cluster analyzes, which can be used as a training tool for radiological technologists and as a reference for image quality improvement.
Results
A reference panoramic X-ray image was acquired using a phantom with the Frankfurt plane positioned horizontally, centered in the middle, and frontal plane centered on the canine teeth. Other images with positioning errors were acquired with anteroposterior shifts, vertical rotations of the Frankfurt plane, and horizontal left/right rotations. The reference and positioning-error images were evaluated with the cross-correlation coefficients for the occlusal plane profile, left/right angle difference, peak signal-to-noise ratio (PSNR), and deformation vector fields (DVF). The results of the image analyzes were scored for positioning-error images using K-means clustering analysis. Next, we analyzed the correlations between the total score, cross-correlation analysis of the occlusal plane curves, left/right angle difference, PSNR, and DVF. In the scoring, the positioning-error images with the highest quality were the ones with posterior shifts of 1 mm. In the analysis of the correlations between each pair of results, the strongest correlations ( r = 0.7–0.9) were between all combinations of PSNR, DVF, and total score.
Conclusions
The scoring of positioning-error images using K-means clustering analysis is a valid evaluation indicator of correct patient positioning for technologists in training.
... In a survey of US orthodontists conducted by the Journal of Clinical Orthodontics, 68% of clinicians reported that they took progress panoramic radiographs, and 76% of participants reported that they took post-treatment panoramic radiographs to evaluate final root position [17]. On the other hand, some studies have indicated that panoramic radiographs are not enough accurate to detect root position, especially in the canine and first premolar areas; therefore, this method could be misleading [18][19][20]. To get optimal positioning of dental roots, a three-dimensional pre-treatment representation of all the teeth would be required. ...
... Therefore, accurate bracket positioning is necessary. Currently, root position is primarily evaluated according to panoramic radiographs but, however, these often contain distortions [18][19][20]. Although the introduction of CBCT has been helpful in orthodontics by enabling 3D positioning of the roots even with a reduced quantity of X-rays [35,36], based on the ALARA (As Low As Reasonably Achievable) principle the root position should not be replaced by CBCT [31,32]. ...
Introduction:
This study aimed to obtain information on the relationship between crown and root in terms of morphology - dimensions and crown-root angles -to be used for orthodontic set-ups without the use of radiological examinations.
Material and methods:
All the good quality CBCTs of patients obeying the eligibility criteria, from 2000 to 2015, were analysed. All teeth were analysed except for third molars. Six variables were evaluated: crown (CL) and root length (RL), crown width (CW), root width (RW), crown-root angles in both the frontal (CR-frontal) and sagittal plane (CR-sagittal). All teeth were divided into 3 groups according to number of root (single, two, three-rooted). The measurements were assessed with the Invivo professional software and then, subjected to correlation matrices and linear regression statistical analysis in order to find any significant correlations between crown and root measurements (α≤0.05).
Results:
Seventy-three out of 247 good quality CBCTs were assessed. Correlation matrices statistical analysis showed linear correlations for some variables investigated, especially for CW/RW pairing in all subgroups (r=0.81, r=0.70 and r=0.58 respectively for single-, two- and three-rooted) and CL/RL in the single-rooted subgroup (r=0.29). Subsequent linear regression analysis allowed to obtain information about roots starting from crown measurements by means of equations [RW=0.76+(0.73×CW) and RL=10.94+(0.25×CL) for single-rooted teeth; RL=1.11+(0.73×CW) and RW=0.99+(0.76×CW), respectively for single- and two-rooted teeth]. No linear correlation was found between crown measurements and C-R angular values.
Conclusion:
It is possible to obtain root information starting from some crown measurements but these do not fulfil the need of minimal information to guarantee a perfect root position starting from that of crown.
... Especially vertical head rotations (5° up and 5° down) influence the angulation of maxillary teeth. 31 Interpretation of the angular measurements must therefore be done with the greatest care. These problems can be solved by using three-dimensional radiographs, but the routine use of cone-beam computed tomography (CBCT) for screening of impacted M3 is not justified taken into account the ALARA principle. ...
Objectives:
To prospectively follow up a previously reported sample, analyzing (1) changes in third molar (M3) position after completion of 2 different types of orthodontic treatment: (2) non-extraction treatment with (HG) vs without cervical headgear (non-HG) and (3) first or second premolar extractions (PM1-2) compared to a non-extraction group (NE).
Methods:
A total of 474 patients were prospectively followed up. Panoramic radiographs were taken pre- (T1), post-treatment (T2) and at follow-up (T3). T3 records (a mean of three years after treatment) were available for 135 (HG vs non-HG) and 134 patients (PM1-2 vs NE), respectively. Angulation, vertical position, relation with the mandibular canal and mineralization status of M3 at T2 and T3 were statistically compared.
Results:
The HG group presented more M3 with ideal vertical orientation at T3. In NE-cases, further improvement in angulation and orientation can be expected after debonding, as well as a deterioration in the relationship with the mandibular canal. Extractions accelerated upper M3 vertical eruption and PM2 extractions led to long-term larger lower retromolar spaces.
Conclusions:
The use of cervical headgear increased upper M3 uprighting three years after debonding, while little changes in M3 position were found after orthodontic treatment with extractions. However, PM2 extractions led to larger retromolar spaces and better M3 angulation in the long term.
... Panoramic radiographs, which are an important part of orthodontic diagnosis and treatment planning, are not entirely excellent diagnostic records [7]. It has been reported that their poor quality and/or distorted images may be due to various factors ranging from errors in imaging technique to incorrect head positioning [8,9]. However, Hardy et al. [10] reported that panoramic radiographs guide the placement of orthodontic brackets; hence, are an important mainstay for the assessment of the mesiodistal axial inclination of teeth. ...
i) Objective: Changes in the mesiodistal axial angulations of teeth with orthodontic treatment have been a topic of interest in orthodontics for many years, although it has not been clarified enough yet. Therefore, this present study aimed to compare mesiodistal axial angulations of canine and first molar teeth by measuring from pre-and post-treatment panoramic radiographs in different types of orthodontic malocclusions. (ii) Materials and Methods: In the study, the mesiodistal axial angulation angles of the lower-upper canines (teeth numbered 13, 23, 33, and 43) and first molars (teeth numbered 16, 26, 36, and 46) were compared on panoramic radiographs taken pre-(T0) and post-(T1) orthodontic treatment of 353 patients: 237 female (mean age 14.74 ± 2.96) and 116 male (mean age 14.44 ± 2.50), who had not received any prior orthodontic treatment. The groups were formed according to pre-/post-treatment, gender, angle classification, skeletal classification, bilaterally first premolar extraction/non-extraction, and the use/non-use of miniscrews in the extraction cases. The mesiodistal angulations between the long axes of both the lower and upper canines and first molars and the interorbital plane were measured separately and recorded. The reliability analysis between the repeated measurements was evaluated using the intraclass correlation coefficient (ICC). For statistical analysis, a paired sample t-test and Wilcoxon test were used for the normally and non-normally distributed data, respectively. For the between-groups comparison, independent sample t-test and one-way ANOVA were used for normally distributed data, while the Mann-Whitney U and Kruskal-Wallis tests were used for non-normally distributed data. A value of p < 0.05 was considered statistically significant. (iii) Results: ICCs showed excellent reliability, ranging from 0.804 to 0.913 in other teeth, yet were good in tooth 43 (ICC = 0.712). Regardless of the groups, statistically significant differences were found between the T0 and T1 angulations for all teeth, except teeth 13 and 16. In all groups, the increase in the angulations of teeth 33 and 43 and the decrease in the angulations of teeth 36 and 46 (except skeletal class 3) were found to be statistically significant. The T0 and T1 angulation changes in the miniscrews in the used and non-used groups in extraction cases were similar to the differences found in all teeth, regardless of the groups. There was no significant difference between gender, skeletal classes, and angle classes in the amounts of change in the mesiodistal angulations. (iv) Conclusion: It was concluded that orthodontic treatment caused significant changes in the mesiodistal axial angulation of the canine and the first molar teeth. Furthermore, the fact that the angulations tended to increase in the lower canine teeth and decrease in the lower first molar teeth revealed the importance of tooth movement control, especially in orthodontic mechanics in the mandibula.
... To reduce variations in technique and operator, all OPGs were recorded by a single radiographic technician. 34 That is, the OPG is suitable for assessing the angles and distances related to M3. ...
Objectives:
The early or delayed surgical removal of an asymptomatic lower third molar (M3) in orthodontic patients remains controversial. This study aimed to determine the changes in the impacted level of M3 such as angulation, vertical position, and eruption space, after orthodontic treatment in 3 groups, namely non-extraction (NE), first premolar (P1) extraction, and second premolar (P2) extraction.
Methods:
Relevant angles and distances related to 334 M3s from 180 orthodontic patients were assessed pre- and posttreatment. Angle between lower second molar (M2) and M3 (M3-M2) was used for evaluating M3 angulation. For M3 vertical position, distances from occlusal plane to the highest cuspid (Cus-OP) and fissure (Fis-OP) of M3 were used. Distances from the distal surface of M2 to anterior border (J-DM2) and centre (Xi-DM2) of the ramus were used for assessing M3 eruption space. Pre- and posttreatment values of the angle and distance in each group were compared using a paired-sample t test. Measurements of the 3 groups were compared using analysis of variance. Hence, multiple linear regression (MLR) analysis was used to determine significant factors that impacted changes in M3s' related measurements. Independent factors used for MLR analysis included sex, treatment starting age, pretreatment respective angle/distance, and premolar extraction (NE/P1/P2).
Results:
M3 angulation, vertical position, and eruption space at posttreatment were significantly different from those at pretreatment in all 3 groups. MLR analysis showed that P2 extraction significantly improved M3 vertical position (P < .05) and eruption space (P < .001). P1 extraction significantly decreased Cus-OP (P = .014) and eruption space (P < .001). Treatment starting age was significant factor that affected Cus-OP (P = .001) and M3 eruption space (P < .001).
Conclusions:
After orthodontic treatment, M3 angulation, vertical position, and eruption space changed in favour of the impacted level. These changes in the 3 groups were clearer in order: NE, P1, and P2, respectively.
... Thus, a better tool may be needed to check it more accurately. [8][9][10][11][12] Treatment simulation is essential for orthodontic treatment with the extraction of permanent teeth. Conventional orthodontic setup only uses crowns. ...
Objective:
The purpose of the present study was to compare the root positions in virtual tooth setups using only crowns in a simulated treatment with those achieved in the actual treatment.
Methods:
Pre- and post-treatment intraoral and corresponding cone beam computed tomography (CBCT) scans were obtained from 15 patients who underwent orthodontic treatment with premolar extraction. A conventional virtual tooth setup was used for the treatment simulation. Pre- and post-treatment three-dimensional digital tooth models were fabricated by integrating the patients' intraoral and CBCT scans. The simulated root positions in the virtual setup were obtained by merging the crown in the virtual setup and root in the pre-treatment tooth model. The root positions of the simulated and actual post-treatment tooth models were compared.
Results:
Differences in root positions between the simulated and actual models were > 1 mm in all teeth, and statistically significant differences were observed (p < 0.05), except for the maxillary lateral incisors. The differences in the inter-root angulation were > 1° in all teeth, and statistically significant differences were observed in the maxillary and mandibular canines.
Conclusions:
The virtual tooth setup using only crown data showed errors over the clinical limits. The clinical application of a virtual setup using crowns and roots is necessary for accurate and precise treatment simulation, particularly in extraction treatment.
... Based on the literature review, the clinical significance for angular measurements was set at 2.5 . 29,[40][41][42][43] The percent accuracy was determined by following the protocol and equation used by the previous studies 29, 30 : (2) and (3) are shown in aqua. The same points were then placed for each tooth (consistently at the same location across models); B, Presurgical DDM (yellow); C, ClinCheck model (blue). ...
Introduction
Orthodontists, surgeons, and patients have taken an interest in using clear aligners in combination with orthognathic surgery. This study aimed to evaluate the accuracy of tooth movements with clear aligners during presurgical orthodontics using novel 3-dimensional superimposition techniques.
Methods
The study sample consisted of 20 patients who have completed presurgical orthodontics using Invisalign clear aligners. Initial (pretreatment) digital dental models, presurgical digital dental models, and ClinCheck prediction models were obtained. Presurgical models were superimposed onto initial ones using stable anatomic landmarks; ClinCheck models were superimposed onto presurgical models using surface best-fit superimposition. Five hundred forty-five teeth were measured for 3 angular movements (buccolingual torque, mesiodistal tip, and rotation) and 4 linear movements (buccolingual, mesiodistal, vertical, and total scalar displacement). The predicted tooth movement was compared with the achieved amount for each movement and tooth, using both percentage accuracy and numerical difference.
Results
Average percentage accuracy (63.4% ± 11.5%) was higher than in previously reported literature. The most accurate tooth movements were buccal torque and mesial displacement compared with lingual torque and distal displacement, particularly for mandibular posterior teeth. Clinically significant inaccuracies were found for the buccal displacement of maxillary second molars, lingual displacement of all molars, intrusion of mandibular second molars, the distal tip of molars, second premolars, and mandibular first premolars, buccal torque of maxillary central and lateral incisors, and lingual torque of premolars and molars.
Conclusions
Superimposition techniques used in this study lay the groundwork for future studies to analyze advanced clear aligner patients. Invisalign is a treatment modality that can be considered for presurgical orthodontics—tooth movements involved in arch leveling and decompensation are highly accurate when comparing the simulated and the clinically achieved movements.
... 6 Nonetheless, panoramic x-rays have inherent image distortions from incorrect focal trough size and shape, projection effects from non-orthogonal x-rays beams directed at teeth, and errors in head positioning. [7][8][9] Buccolingual inclination of incisors 10 and molars can be evaluated using, respectively, lateral and posteroanterior cephalograms, but 2D cephalometric measurements are subject to tracing and landmark identification errors, 11 structural superimpositions, inconsistencies with radiographic equipment, patient positioning and/or distortion due to patient movement. 12 In contrast, cone-beam computed tomography (CBCT) scans accurately evaluate root positions, dental buccolingual and mesiodistal angulations and dentofacial structures. ...
... Current commercial software such as OrthoAnalyzer ® (3Shape A/S), 31 iTero ® (Align Technology, Inc) 32 The present study considered the percentages of measures between a range of 2.5° and between 5° ( to 73% of root angulations falling outside this clinically acceptable range when measured. 8,9 In the study of Lee at al, 17 the average of 5 times repeated measurements was used to compare post-treatment setups to post-treatment CBCTs, with a 2.5° clinically acceptable range. ...
... 6 Nonetheless, panoramic x-rays have inherent image distortions from incorrect focal trough size and shape, projection effects from non-orthogonal x-rays beams directed at teeth, and errors in head positioning. [7][8][9] Buccolingual inclination of incisors 10 and molars can be evaluated using, respectively, lateral and posteroanterior cephalograms, but 2D cephalometric measurements are subject to tracing and landmark identification errors, 11 structural superimpositions, inconsistencies with radiographic equipment, patient positioning and/or distortion due to patient movement. 12 In contrast, cone-beam computed tomography (CBCT) scans accurately evaluate root positions, dental buccolingual and mesiodistal angulations and dentofacial structures. ...
... Current commercial software such as OrthoAnalyzer ® (3Shape A/S), 31 iTero ® (Align Technology, Inc) 32 The present study considered the percentages of measures between a range of 2.5° and between 5° ( to 73% of root angulations falling outside this clinically acceptable range when measured. 8,9 In the study of Lee at al, 17 the average of 5 times repeated measurements was used to compare post-treatment setups to post-treatment CBCTs, with a 2.5° clinically acceptable range. ...
Objective
Standard methods of evaluating tooth long axes are not comparable (digital dental models [DDMs], panoramic and cephalometric radiographs) or expose patients to more radiation (cone‐beam computed tomography [CBCT]). This study aimed to compare angular changes in tooth long axes using DDMs versus using CBCTs.
Settings and sample population
Secondary data analysis of DDMs and CBCTs, taken before and after orthodontic treatment with piezocision of 24 patients.
Methods
Angular changes in tooth long axes were evaluated using landmarks on first molars (center of the occlusal surface and center of the furcation), canines and incisors (cusp tip and center of the root at the cementoenamel junction). Wilcoxon test, intraclass correlation coefficient (ICC) and Bland‐Altman plots were used to test intra‐ and inter‐rater agreement and compare DDM and CBCT measurements.
Results
The mesiodistal angulation and buccolingual inclination DDM measurements were reproducible. Overall mean differences between DDM and CBCT measurements of mesiodistal angulation, 1.9°±1.5°, and buccolingual inclination, 2.2±2.2°, were not significant for all teeth. ICC between DDM and CBCT measurements ranged from good (0.85 molars) to excellent (0.94 canines; 0.96 incisors). The percentages of measurements outside the range of ±5 were 17.4% for molars, 13.8% for canines, and 4.5% for incisors.
Conclusions
DDM assessment of changes in tooth long axes has good reproducibility and yields comparable measurements to those obtained from CBCT within a 5° range. These findings lay the groundwork for machine learning approaches that synthesize crown and root canal information towards planning tooth movement without the need for ionizing radiation scans.
... Significant inaccuracies in mesiodistal tooth angulations found in PAN were described by previous investigators. PAN inaccuracies have been reported to include variable vertical and horizontal magnification factors, projection geometry, focal trough depth and geometry, and positioning errors of the patient [23][24][25][26]. ...
Backgound
This study aimed to compare panoramic radiography (PAN) and cone beam computed tomography (CBCT) determinations of implant-to-root dimensions (IRD) in anterior and posterior maxillary regions, and to help determine in which instances increased radiation exposure from CBCT scans may be justified.
Methods
IRD measured by PAN (PAN-D) from implant-to-root sites (central incisor, lateral incisor, canine, first premolar, and second premolar) was collected from 418 implant sites in 110 adults. The CBCT technique was used as the reference method for the estimation of IRD. The PAN analysis equations were developed using stepwise multiple regression analysis and the Bland–Altman approach was applied to assess the agreement between PAN and CBCT methods.
Results
The odds ratio that an implant at the canine-to-first premolar (9.7:1) (P = 0.000) or at the first premolar-to-second premolar region (4.5:1) (P = 0.000) belongs to the underestimation group was strong and highly significant. The root mean square error (RMSE) and pure error (PE) were highest for the canine-to-first premolar (RMSE = 0.886 mm, PE = 0.45 mm) and the first premolar-to-second premolar region (4.5:1) (RMSE = 0.944 mm, PE = 0.38 mm).
Conclusions
This study provides evidence of site-specific underestimations of available horizontal bone dimensions for implants when assessed by PAN. These data suggest that the canines and first and second premolars may have to be excluded when assessing root angulations via PAN.
