Comparison of linear and angular changes assessed in digital dental models and cone-beam computed tomography

Measurement of orthodontic tooth movement in lower anterior teeth by means of magnetic resonance imaging- a prospective pilot study

BACKGROUND

During orthodontic treatment, the risk of gingival recession may increase, especially in the mandibular anterior region due to thin alveolar bone. This prospective pilot study aimed to develop a standardized evaluation method based on magnetic resonance imaging (MRI) for analysing tooth movements and tissue dimensions and to investigate the impact on periodontal parameters during orthodontic levelling.

MATERIALS AND METHODS

Participants aged 12 to 18 with lower jaw crowding underwent MRI scans before (T0) and five months into orthodontic treatment (T1). The following tissue dimensions were analysed: thickness of free and supracrestal gingiva (FGT, SGT), thickness of buccal alveolar bone (ABT) at three measurement levels (ABT2, ABT4, ABT8), and gingiva and alveolar bone height (GH, ABH). Additionally, tooth positions (apex position and tooth axis inclination) were determined.

RESULTS

Ten patients (60% female, 40% male) aged 14.33 ± 1.35 years were included after the exclusion of 3 datasets due to motion artefacts. MRI measurements showed significant changes in tooth inclination (2.93 ± 4.77°, p < 0.001), bucco-lingual apex position (-0.45 ± 1.03 mm, p = 0.006), SGT (-0.07 ± 0.19 mm, p = 0.020), ABT8 (0.42 ± 0.59 mm, p < 0.001), ABH (-0.29 ± 0.68 mm, p = 0.006) and GH (0.31 ± 0.9 mm, p = 0.030) between T0 and T1. Inclination changes correlated negatively with FGT (R = -0.422, p < 0.001) and positively with ABT8 (R = 0.404, p = 0.032). Furthermore, ABT8 correlated negatively with buccal apex movement (R=-0.392, p = 0.042). Intra- and interclass correlation coefficients were excellent (0.988 and 0.975).

CONCLUSION

Periodontal tissue changes correlated with tooth inclination or apex position changes due to orthodontic treatment. The pilot study has demonstrated the feasibility of dental MRI as a radiation-free alternative to cone-beam computed tomography for monitoring orthodontic treatment. However, the methodology was susceptible to motion artefacts.

TRIAL REGISTRATION

ISRCTN, ISRCTN12689212. Registered 11 April 2024 Retrospectively registered, http//www.isrctn.com/ISRCTN12689212 .

Closure of maxillary lateral incisor agenesis space in unilateral cleft lip and palate: a digital model assessment

OBJECTIVE

To compare dental positional and gingival parameters of maxillary anterior teeth in unilateral cleft lip and palate (UCLP) after orthodontic treatment with canine substitution due to lateral incisor agenesis.

METHODS

This split-mouth study comprised 57 subjects with UCLP (31 male, 26 female) and agenesis of maxillary lateral incisor at the cleft side, from a single center. Canine substitution was completed after the secondary alveolar bone graft. Dental models were taken between 2 to 6 months after debonding (mean age: 20.4 years). The following variables were measured in the maxillary anterior teeth: crown height, width, proportion, and symmetry, as well as steps between incisal edges, gingival margins, tooth mesiodistal angulation and labiolingual inclination. Paired t-tests with Bonferroni post-hoc correction was used for comparisons between cleft and non-cleft sides (p<0.05).

RESULTS

At the cleft side, canines replacing missing lateral incisors had a higher crown height (0.77mm) and an increased width (0.67mm), and first premolars showed a shorter crown height (1.39mm). Asymmetries were observed in the gingival level of central and lateral incisors, with a greater clinical crown at the cleft side (0.61 and 0.81mm, respectively). Cleft side central incisors were more upright than their contralaterals (2.12º).

CONCLUSIONS

Maxillary anterior teeth demonstrated positional, size and gingival height differences between cleft and non-cleft side after space closure of maxillary lateral incisor agenesis. Slight asymmetries in tooth position and gingival margin in the maxillary anterior teeth should be expected after orthodontic treatment in UCLP patients.

Assessment of the accuracy of laser-scanned models and 3-dimensional rendered cone-beam computed tomographic images compared to digital caliper measurements on plaster casts

Purpose

This study investigated the accuracy of laser-scanned models and 3-dimensional (3D) rendered cone-beam computed tomography (CBCT) compared to the gold standard (plaster casts) for linear measurements on dental arches.

Materials and Methods

CBCT scans and plaster models from 30 patients were retrieved. Plaster models were scanned by an Emerald laser scanner (Planmeca, Helsinki, Finland). Sixteen different measurements, encompassing the mesiodistal width of teeth and both arches' length and width, were calculated using various landmarks. Linear measurements were made on laser-scanned models using Autodesk Meshmixer software v. 3.0 (Autodesk, Mill Valley, CA, USA), on 3D-rendered CBCT models using OnDemand 3D v. 1.0 (Cybermed, Seoul, Korea) and on plaster casts by a digital caliper. Descriptive statistics, the paired t-test, and intra- and inter-class correlation coefficients were used to analyze the data.

Results

There were statistically significant differences between some measurements on plaster casts and laser-scanned or 3D-rendered CBCT models (P<0.05). Molar mesiodistal width and mandibular anterior arch width deviated significantly different from the gold standard in both methods. The largest mean differences of laser-scanned and 3D-rendered CBCT models compared to the gold standard were 0.12±0.23 mm and 0.42±0.53 mm, respectively. Most of the mean differences were not clinically significant. The intra- and inter-class correlation results were acceptable for all measurements (>0.830) and between observers (>0.801).

Conclusion

The 3D-rendered CBCT images and laser-scanned models were useful and accurate alternatives to conventional plaster models. They could be used for clinical purposes in orthodontics and prostheses.

Comparison of the effect of using panoramic and cone-beam computed tomography on the accuracy of root position in indirect digital bracket placement: A retrospective study

OBJECTIVE

The purpose of this study was to compare the root position accuracy of the use of panoramic radiography and cone-beam computed tomography (CBCT) in the indirect digital bracket placement.

METHODS

Two hundred and eighty-six maxillary and 300 mandibular teeth of 27 patients who have digital model, panoramic image and CBCT scan were included to the study. Indirect digital bonding was performed by using digital models and panoramic images in Group 1 and by superimposing the CBCT on the digital models with the OrthoAnalyzer™ 2020 (3Shape, Copenhagen, Denmark) software in Group 2. Angular measurements were calculated with 3-dimensional superimposition of the positions of the brackets placed with the Gom Inspect 2020 software. In the statistical analysis, One-way Analysis of Variance (ANOVA) and the Paired t test were used.

RESULTS

Maxillary canines had the highest angular deviation at 5.56°± 4.01° in comparison with the maxillary teeth (P < .001). Mandibular canines and second premolars had the highest angular deviation in the comparison between mandibular teeth (P < .001). Considering the groups of ranges by clinical limits of the deviations, these differences were significant in the angular dimensions with 3.57° ± 2.59° (P < .001). The amount of deviation of all teeth was found 3.57° ± 2.59°in the study.

CONCLUSIONS

Using panoramic images or CBCT in the digital bonding had clinical significantly effects on the angular deviation of bracket position. These findings may be taken into consideration when implementing bracket placement in indirect digital bonding. Despite the successful results, indirect digital bonding should not be the single reason to take the CBCT from the patients.

Dental long axes using digital dental models compared to cone-beam computed tomography

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 vs 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 (centre of the occlusal surface and centre of the furcation), canines and incisors (cusp tip and centre 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.