The variability of the curvature of the labial surface of the upper anterior teeth along the facial axis of the clinical crown

Influence of repositioning guides' color and usage on precision in tooth color measurement with a clinical spectrophotometer

BACKGROUND

Repositioning guides are commonly employed in clinical studies to ensure consistent tooth color measurements. Yet, their influence on measured color remains uncertain.

OBJECTIVE

This study evaluated the impact of repositioning guides' color and usage on tooth color measurement using a clinical spectrophotometer.

METHODOLOGY

In total, 18 volunteers participated in this study, in which the color of their upper left central incisor and upper left canine was measured with or without repositioning guides (control). The guides were made from pink, blue, or translucent silicone, as well as an acetate-based bleaching tray. Tooth color was measured in triplicates using a clinical spectrophotometer based on the CIELAB system. The standard deviations of these readings were used to estimate reproducibility, and color differences (ΔE00) between the measurements with guides and the control were calculated.

RESULTS

Repositioning guides had a minimal effect on L* values and no effect on b* values. The use of pink silicone increased a* values, whereas blue or translucent silicone reduced them. Irrespective of the evaluated tooth, the lowest ΔE00 values were observed for the translucent silicone and bleaching tray. The usage of guides only affected data variability for the L* color coordinate.

CONCLUSION

Using repositioning guides can significantly impact the precision of tooth color measurement with a clinical spectrophotometer.

Evaluation of effectiveness and efficiency of fixed orthodontic treatment comparing standard and computer-aided design and manufacturing conventional bracket systems using indirect bonding for both: A retrospective study

BACKGROUND

To compare the effectiveness and efficiency of orthodontic treatment (OT) with standard versus computer-aided design and computer-aided manufacturing (CAD/CAM) indirect bonding of conventional brackets.

METHODS

This retrospective study examined two groups: standard indirect bonding group (12 males, 13 females; mean age 12.21 ± 0.52 years), and digital indirect bonding group (11 males, 14 females; mean age 12.76 ± 1.32 years), treated via a CAD/CAM indirect bonding system. Conventional brackets were used in both groups. Pretreatment and post-treatment records were acquired for all subjects. Weighted Peer Assessment Rating (W-PAR) index was used to assess the effectiveness of OT, in conjunction with five angular cephalometric measurements (ANB°, Sn-GoGn°, U1-PP°, IMPA° and FMA°) and comparatively analyzed using generalized mixed-effects models and post hoc test. Treatment efficiency was assessed in terms of the numbers of bracket repositionings, archwire bends, accidental bracket debondings, appointments and treatment months. Comparative analysis of efficiency was performed using the asymptotic Wilcoxon-Mann-Witney test. Statistical significance was set at 5%.

RESULTS

Total W-PAR and W-PAR component scores decreased significantly during treatment for both groups and in a similar way. Cephalometric measures ANB° and IMPA° significantly decreased and increased, respectively. Significantly fewer bracket repositionings, number of appointments and treatment months were recorded in group digital indirect bonding.

CONCLUSIONS

Although both methods investigated were effective to achieve good outcomes, CAD/CAM indirect bonding method increased the efficiency of OT, when conventional brackets are used.

Augmented reality in orthodontics for bracket placement using conventional mobile devices: Technical note

BACKGROUND

Improving bracket placement accuracy through computer-aided design and a bracket navigation set supported by augmented reality (AR).

METHODS

A technical workflow was developed for implementing AR-assisted orthodontic bracket positioning through a smartphone application. This innovative approach eliminates the need for three-dimensional radiation imaging or physical guides, making it a safe and convenient option for clinical use by overlapping the digitally planned bracket position over the patient clinical crown for a precise recommendation of bracket positioning.

RESULTS

It was found that it is achievable and can be easily recognized from all view angles, and this proves that new techniques with new opportunities could be considered.

CONCLUSIONS

AR smartphone applications can potentially be used for the accurate placement of dental brackets; thus, such applications show promise for use in the field of orthodontics.

Accuracy of indirect bracket placement with medium-soft, transparent, broad-coverage transfer trays fabricated using computer-aided design and manufacturing: An in-vivo study

INTRODUCTION

The objective of this study was to test the precision of in-vivo indirect bracket placement via medium-soft, transparent, broad-coverage, computer-aided designed and manufactured transfer trays using an automated digital method.

METHODS

Seventeen patients requiring vestibular fixed appliances were consecutively recruited, and bonding accuracy was measured at each bracket, evaluating 3 linear (mesiodistal, buccolingual, and vertical) and 3 angular measurements (torque, tip, and rotation) with an automated method involving digital superimposition of individual teeth. Mean and standard deviation values were calculated for both arches, single arch, and tooth type, and the percentages of single deviations over the thresholds of 0.25 mm and 1° were calculated, as well as maximum and minimum values for each deviation and directional bias. Correlations between each variable (arch, tooth type, and single tooth) and deviations were investigated through classification and regression trees (CART) predictive models.

RESULTS

Neither mean nor single linear deviations ever exceeded the set cutoff value of 0.25 mm. Mean angular deviations never exceeded 1°, but some individual angular deviations did, specifically 8.31% of torque, 13.16% of tip, and 7.16% of rotation deviations. The highest percentage of deviation was recorded for rotation of the maxillary incisors (18.11%). No evident trend in directional deviation bias was found. Tooth type appears to influence mesiodistal and torque deviations, whereas the single tooth variable influenced the percentage of rotation deviations exceeding 1° (P <0.05).

CONCLUSIONS

This computer-aided designed and manufactured medium-soft, transparent transfer tray provides accurate bracket placement and could be recommended for routine fixed appliance treatment.

Analysis of tooth anatomy in adults with ideal occlusion: A preliminary study

INTRODUCTION

The aim of this study was to investigate the vestibular anatomy of teeth in samples of adult Italian and Mozambican subjects in ideal occlusion and permanent dentition and identify any anatomic characteristics that may influence bonding in the straight-wire technique.

METHODS

Linear measurements and coordinates of each curve representing the clinical crown height and width of each tooth were acquired from digital models of each subject categorized to 1 of 2 groups: Italian (18 males, 22 females; mean age, 29.6 ± 5.7 years) or Mozambican (14 males, 15 females; mean age, 23.4 ± 5.9 years). All subjects had normal dentition and no previous orthodontic treatment, fillings, or prostheses. Method error and systematic error were calculated according to the Dahlberg formula (S² = ∑ d²/2n) and dependent Student t test (P <0.05), respectively. Tooth symmetry was investigated through a paired-samples t test (P <0.05) and sex difference via an independent-samples t test (P <0.05). After neither asymmetry nor sexual dimorphism was found, all data were pooled, inverting the signs of the X coordinates and then mirroring data. Subsequently, a 2-samples t test (P <0.05) and a multivariate cluster analysis were performed on the mirrored data to compare the 2 groups and to identify any within-group diversity for number of clusters for each tooth. Means of all linear measurements and coordinates (crown height and width) calculated for each cluster were reported and compared using a standard 2-samples t test (P <0.05).

RESULTS

Two clusters were identified for the maxillary second premolars and molars in Italian subjects, whereas in the Mozambican subjects, there were 2 clusters for the maxillary first premolars and lateral incisors and 3 clusters for the maxillary canines and central incisors. The mandibular arch was remarkably homogeneous, with only 1 cluster per tooth in each group. In the mandibular arch, statistical differences were recorded between ethnic groups in crown height at the central incisors and second molars and in crown width in the sector from the second premolar to the second molar.

CONCLUSIONS

There were considerable differences both between and within racial groups in crown height, crown width, and numbers of clusters, which should be taken into account during bonding. Although single-bracket placement guides specific for ethnicity may be feasible for the mandibular arch, the significant diversity in number of clusters in the maxillary arch indicates that more accurate bracket placement guides that take into account such heterogeneity are required.

Correlation between Dental Vestibular-Palatal Inclination and Alveolar Bone Remodeling after Orthodontic Treatment: A CBCT Analysis

The aim of this study was to evaluate the correlation between dental vestibular-palatal inclination changes and the cortical bone remodeling after fixed orthodontic treatment using cone beam computed tomography (CBCT). Twenty-two patients with Angle Class I malocclusion, permanent dentition, and mild to moderate dental crowding were included in the present three-dimensional (3D) analysis. Bone dimensions were evaluated by CBCT scans obtained before and after orthodontic treatment, whereas the torque values were calculated by means of digital models using the 3D VistaDent software. A paired t-test was used to compare the changes between the pretreatment and post-treatment measurements. The correlations between variables were analyzed with linear regression analysis. A significant correlation between torque variations and bone thickness changes was observed for the apical buccal level of the anterior side (P < 0.05). Limited and not significant alveolar bone resorption for the apical thickness of anterior teeth occurred at ± 5 degrees of torque variation, while for tooth inclination exceeding +5 or -5 degrees, the bone remodeling was more evident. The present study demonstrated that anterior region was the most affected area by bone remodeling and that torque variation was highly related to apical bone thickness adaptation for maxillary and mandibular incisors and maxillary canines.

Evaluation of crown inclination and angulation after orthodontic treatment using digital models : Comparison to the prescription of the brackets used

PURPOSE

To compare crown inclination and angulation results obtained after orthodontic treatment to the Roth prescription.

METHODS

The study design was based on files and documents obtained from a database of 26 patients who had undergone orthodontic treatment using the straight-wire technique and the Roth prescription. The crown inclination and angulation were measured using a three-dimensional (3D) cephalometric module (VistaDent, Dentsply, New York, NY, USA) by an orthodontist. A coordinate system (x, y, z) was developed for each tooth that used the Andrews plane as a para-axial reference. Descriptive statistical analysis provided the mean and standard deviation (SD) of crown inclination and angulation obtained after orthodontic treatment, which were compared to the Roth prescription.

RESULTS

Method reproducibility is an important test to investigate the margin of error and to verify the reliability of results. The results at time 1 (1.6° ± 1.1°) and time 2 (1.7° ± 1.2°) of the pilot study were not statistically different (p = 0.99). Maxillary lateral and central incisors presented significant differences in crown angulation (p < 0.05) compared to the Roth prescription. The crown angulation of maxillary second premolars with regard to the occlusal plane presented a similar value to the Roth prescription.

CONCLUSION

Crown inclination and angulation found at the end of orthodontic treatment did not match the prescription of the brackets for most teeth, as measured using digital models.

A three-dimensional comparison of torque achieved with a preadjusted edgewise appliance using a Roth or MBT prescription

OBJECTIVE

To investigate if there are any significant differences in the final inclination of the upper and lower anterior teeth of patients treated with a Roth or an MBT bracket prescription.

MATERIALS AND METHODS

Forty sets of posttreatment study models from patients treated using a preadjusted edgewise appliance (20 Roth and 20 MBT) were selected using predetermined inclusion and exclusion criteria. The models were masked and laser-scanned, and the final crown inclinations of UL1, UR3, and LR1 were assessed from the digital images. A two-way analysis of variance was undertaken with the dependent variable of final crown inclination and independent variables of bracket prescription (Roth or MBT) and tooth type.

RESULTS

There were no statistically significant differences in terms of the final inclination of the anterior teeth between the two bracket prescriptions (P  =  .132). Statistically significant differences were found between the final inclinations of different tooth types investigated (P < .001).

CONCLUSION

In this group of selected patient records, the differences in torque values between the two bracket prescriptions did not lead to any real clinically detectable differences in the final inclination of teeth.

Assessment of clinical outcomes of Roth and MBT bracket prescription using the American Board of Orthodontics Objective Grading System

Background:

There is always a need to assess whether small changes in bracket prescription can lead to visually detectable differences in tooth positions. However, with little clinical evidence to show advantages of any of the popularly used bracket systems, orthodontists are forced to make clinical decisions with little scientific guidance.

Aim:

To compare the orthodontic cases finished with Roth and MBT prescription using American Board of Orthodontics-Objective Grading System (ABO-OGS).

Settings and Design:

Department of Orthodontics, Post-graduate dental college, retrospective cross-sectional study.

Materials and Methods:

Forty patients selected were divided into two groups of 20 patients each finished with straight wire appliance using Roth and MBT prescription, respectively. The examiner ability was assessed and calibrated by one of the ABO certified clinician to grade cases using the OGS.

Statistical Analysis:

Unpaired student t-test was used and P < 0.05 was accepted as significant.

Results and Conclusions:

MBT bracket group had a lower score of 2.60 points in buccolingual inclination and lower score of 1.10 points in occlusal contact category that was statistically significant when compared with Roth group. The difference in total ABO-OGS score was 2.65 points showing that the outcome for the MBT prescription was better than that of the Roth prescription, which is statistically significant, but with little or no clinical significance. It can be concluded that use of either one of the Roth and MBT bracket prescriptions have no impact to the overall clinical outcome and quality of treatment entirely depends on clinician judgment and experience.

Roth versus MBT: does bracket prescription have an effect on the subjective outcome of pre-adjusted edgewise treatment?

The aim was to determine if bracket prescription has any effect on the subjective outcome of pre-adjusted edgewise treatment as judged by professionals. This retrospective observational assessment study was undertaken in the Orthodontic Department of the Charles Clifford Dental Hospital, Sheffield, UK. Forty sets of post-treatment study models from patients treated using a pre-adjusted edgewise appliance (20 Roth and 20 MBT) were selected. The models were masked and shown in a random order to nine experienced orthodontic clinicians, who were asked to assess the quality of the outcome, using a pre-piloted questionnaire. The principal outcome measure was the Incisor and Canine Aesthetic Torque and Tip (ICATT) score for each of the 40 post-treatment models carried out by the nine judges. A two-way analysis of variance was undertaken with the dependent variable, total ICATT score and independent variables, Bracket prescription (Roth or MBT) and Assessor. There were statistically significant differences between the subjective assessments of the nine judges (P<0.001), but there was no statistically significant difference between the two bracket prescriptions (P = 0.900). The best agreement between a clinician's judgment of prescription used and the actual prescription was fair (kappa statistic 0.25; CI -0.05 to 0.55). The ability to determine which bracket prescription was used was no better than chance for the majority of clinicians. Bracket prescription had no effect on the subjective aesthetic judgments of post-treatment study models made by nine experienced orthodontists.

Three-dimensional analysis of the tooth movement and arch dimension changes in Class I malocclusions treated with first premolar extractions: a guideline for virtual treatment planning

INTRODUCTION

Our objective was to analyze patterns of tooth movement and changes of arch dimension by superimposing 3-dimensional (3D) virtual models.

METHODS

The sample consisted of 24 Korean adults with Class I malocclusion and minimal crowding, treated by first premolar extractions, sliding mechanics (0.022-in MBT brackets [3M Unitek, Monrovia, Calif] with 0.019 × 0.025-in stainless steel wire) and moderate anchorage. The 3D virtual maxillary casts at pretreatment and posttreatment were superimposed with the best-fit method. Linear and angular variables were measured with 3Txer program (Orapix, Seoul, Korea). Wilcoxon signed rank and Mann-Whitney tests were used for statistical analysis.

RESULTS

There was no significant difference in the individual tooth movement between the right and left sides (P > 0.05). For the movement of each tooth, the maxillary central incisors (U1), lateral incisors (U2), and canines (U3) were significantly inclined lingually, extruded, and moved posteriorly and laterally. The maxillary second premolar (U5), first molar (U6), and second molar (U7) had significant mesial inward rotation, anterior movement, and contracted toward the midsagittal plane. The ratio of anteroposterior movement between the maxillary anterior and posterior teeth was 5:1. The amounts of contraction in U5, U6, and U7 were 1.4, 1.3, and 1.2 mm, respectively. When the amount of change between the adjacent teeth were compared, the linguoversion in U1 was significantly greater than that of U2. U3 and U5 showed significant opposite movements in all variables. There were differences only in angulation and vertical displacement between U6 and U7.

CONCLUSIONS

Superimposition of 3D virtual models could be a guideline for precise virtual treatment planning.