Three-dimensional computer-assisted study model analysis of long-term oral-appliance wear. Part 1: Methodology

Does aligner refinement have the same efficiency in deep bite correction?: A retrospective study

BACKGROUND

Refinements are very common in clear aligner treatments. The aim of this study is to assess whether the predictability of deep overbite correction is similar over several refinements using clear aligners (Invisalign, Align Technology, San Jose, Calif) and examine the accuracy of vertical movement and inclination change of individual teeth.

METHODS

This retrospective study included 20 deep bite patients (7M and 13F; 32.63 ± 11.88 years old; an initial overbite of 5.09 ± 0.98 mm), consecutively treated from September 2016 and March 2023, who completed at least two sets of aligners, including refinements. The initial, predicted, and achieved models were exported from ClinCheck or OrthoCAD (Cadent Inc, Carlstadt, NJ) and superimposed via best-fit surface-based registration using SlicerCMF (version 4.9.0; cmf.slicer.org). We also examined 15 out of 20 patients who completed treatments. The overbite correction and changes in vertical movement and inclination for individual teeth were measured. Descriptive statistics and a paired t-test or Wilcoxon signed-rank test were performed. P < 0.05 was considered statistically significant.

RESULTS

The mean accuracy of overbite correction was 37.63% after 1st set, followed by 11.19%, 6.32%, and 13.80% (2nd-4th sets), respectively. There were statistically significant differences between the predicted and achieved vertical movements and inclination changes for all teeth for the 1st and 2nd sets. For the completed cases, the mean overbite correction was 38.54% compared to the initially planned overbite correction, which is similar to one of the 1st set. Still, the vertical movements and inclination changes of all teeth present statistically significant differences between the initially planned and finally achieved movements except for maxillary lateral incisor torque.

CONCLUSIONS

The most overbite correction occurs during the 1st set of aligners, and refinement treatment does not significantly improve the deep bite correction.

A consideration of factors affecting palliative oral appliance effectiveness for obstructive sleep apnea: a scoping review

STUDY OBJECTIVES

This scoping review allows physicians, researchers, and others interested in obstructive sleep apnea to consider effectiveness of oral appliances (OAs). The intent is to improve understanding of OA effectiveness by considering morphologic interaction in patients with obstructive sleep apnea.

METHODS

Morphologic and biomechanical criteria for positional alterations of the mandible assessed success rates of OA appliances. Searches of databases (Medline, PubMed, The Cochrane Library, EBSCO) using terms: OA treatment effectiveness and positive and/or negative outcome predictors. Craniofacial predictors of OAs and obstructive sleep apnea biomechanical factors of anatomical traits associated with OA effectiveness were included. Databases searched radiographic cephalometric imaging for morphology/phenotypes and apnea-hypopnea index responses. Articles were excluded if title or abstract was not relevant or a case report. If the analysis did not report mean or standard deviation for apnea-hypoxia index, it was excluded. No language, age, or sex restrictions were applied.

RESULTS

Analysis of 135 articles included in searched literature indicated alterations in musculature and pharyngeal airway structure through OA use. These alterations were individually unpredictable with wide variability 61.81% ± 12.29 (apnea-hypoxia index mean ± standard deviation). Morphologic variations as predictors were typically weak and idiosyncratic. Biomechanical factors and wide variations in the metrics of appliance application were unclear, identifying gaps in knowledge and practice of OAs.

CONCLUSIONS

An integrated basis to identify morphologic and biomechanical elements of phenotypic expressions of sleep-disordered breathing in the design and application of OAs is needed. Current knowledge is heterogeneous and shows high variability. Identification of subgroups of patients with obstructive sleep apnea responding to OAs is needed.

Three-dimensional analysis of the root canal preparation with Reciproc Blue®, WaveOne Gold® and XP EndoShaper®: a new method in vivo

Background

The purpose of this study was to evaluate the changes in canal volume after root canal preparation in vivo with 3 different single-file techniques (Reciproc-Blue®, WaveOne-Gold® and XP-EndoShaper®), with a new method using CBCT and 3D reconstruction.

Methods

In this prospective study, thirty human lower premolars from healthy patients were used, in which extraction was indicated for orthodontic reasons. All the teeth used were caries- and restoration-free with complete root development, without signs of periodontal disease or traumatic occlusion, and with only one straight canal (up to 25º curvature). Teeth were randomly divided into three different groups: Reciproc-Blue, WaveOne-Gold and XP-EndoShaper. CBCT scans before root canal preparation were used to create a 3D reconstruction with RHINOCEROS 5.0 software to assess the initial canal volume, and then compared with 3D reconstructions after canal preparation to measure the increase in canal volume. Student’s t test for paired data were used to determine statistically significant differences between the before and after canal volumes. Anova test was used to determine statistically significant differences in the percentage of canal volume increase between the groups and Tukey's post-hoc test were used to paired comparison.

Results

Reciproc-Blue showed the higher increase in canal volume, followed by WaveOne-Gold and XP-EndoShaper (p = 0.003). XP-EndoShaper did not show a statistically significant increase in canal volume after root canal preparation (p = 0.06).

Conclusion

With this model, Reciproc-Blue showed higher increase in root canal volume, followed by WaveOne-Gold, while XP-EndoShaper did not significantly increase root canal volume during preparation.

Dentoskeletal effects of oral appliance wear in obstructive sleep apnoea and snoring patients

Objectives

To evaluate the dentoskeletal changes associated with long-term and continuous mandibular advancement device (MAD) use in sleep-related breathing disorder patients.

Methods

Cephalometric measurements and three-dimensional model analysis were performed at baseline and after 3.5 ± 1.1 years in 20 snoring and obstructive sleep apnoea patients treated with the Silensor® appliance. Intra-group differences were compared using paired t-test or Wilcoxon signed-rank test. A regression analysis was performed for variables that showed a statistically significant difference between time points to evaluate the influence of treatment time and patient's initial characteristics on their variations. The statistical significance was set at P < 0.05.

Results

At cephalometric assessment, the maxilla revealed a significant decrease in horizontal position (SNA: -0.4 ± 0.72 degree, P = 0.021) and a significant retroclination of the upper incisor (-1.59 ± 1.07 degree, P < 0.001), while the mandible displayed a significant downward rotation (0.88 ± 1.28 degree, P = 0.006) and a proclination of the lower incisor (2.27 ± 1.38 degree, P < 0.001). Model analysis showed a decrease in upper total space discrepancy (-0.66 ± 0.72 mm, P < 0.002), overjet (OJ; -0.34 ± 0.47 mm, P < 0.011), and overbite (-0.4 ± 0.52 mm, P < 0.004). In the regression analysis, treatment time influenced the lower incisor inclination (Beta = -0.713, P = 0.018) and OJ (Beta = -0.218, P = 0.018); patients' initial characteristics had an effect on OJ (Beta = -0.195, P = 0.011).

Limitations

A larger sample size could increase the generalizability of the findings.

Conclusion

MAD wear after a mean of 3.5 years determines statistically significant but clinically irrelevant dentoskeletal changes. Their potential occurrence should be thoroughly discussed with patients; regular follow-up visits by a specialist experienced in dental sleep medicine are also mandatory during treatment in addition to polysomnographic examinations.

Three-Dimensional Motion Analysis of the 2nd Cervical Spinous Process at End Range Cervical Rotation in Different Scapular Positions Using 3D Digitizer

OBJECTIVE

The study used a 3D digitizer to determine three-dimensional motion analysis of the 2nd cervical (C2) spinous process at end range cervical rotation with the scapula in different positions.

METHODS

30 healthy adults participated in this study. Different scapula positions were adopted bilaterally and positioned passively at normal resting, depression, adduction, and abduction. Under each scapula position, bilateral end range cervical rotation and displacement of the C2 spinous process were analyzed by a 3D digitizer.

RESULTS

Displacement of the C2 spinous process relative to the occiput was significantly correlated with range of cervical rotation under all scapular positions (p<0.05). However, there were no significant differences between end range cervical rotation and displacement of the C2 spinous process relative to the occiput in any scapular position.

CONCLUSION

These results suggest that measurement of upper cervical mobility using the 3D digitizer is a reliable method that holds promise in the evaluation of people with cervical spine disorders.

Superimposition of 3D digital models: A case report

INTRODUCTION

Superimposition of digital models may be performed to assess tooth movement in three dimensions. Detailed analysis of changes in tooth position after treatment may be achieved by this method.

AIM

This article describes the method of superimposing digital models with a clinical case. It emphasizes the difficult procedure of superimposing 3D models in the lower arch. A methodology for superimposing mandibular models acquired with a structured light 3D scanner is discussed.

CONCLUSION

Superimposition of digital models is useful to analyse tooth movement in the three planes of space, presenting advantages over the method of cephalogram superimposition. It seems feasible to superimpose digital models in the lower arch in patients without growth by using a coordinate system based on the palatal rugae and occlusion. The described method aims to advance the difficult procedure of superimposing digital models in the mandibular arch, but further research is nonetheless required in this field.

Wear measurement of dental tissues and materials in clinical studies: A systematic review

OBJECTIVES

This study aims to systematically review the different methods used for wear measurement of dental tissues and materials in clinical studies, their relevance and reliability in terms of accuracy and precision, and the performance of the different steps of the workflow taken independently.

METHODS

An exhaustive search of clinical studies related to wear of dental tissues and materials reporting a quantitative measurement method was conducted. MedLine, Embase, Scopus, Cochrane Library and Web of Science databases were used. Prospective studies, pilot studies and case series (>10 patients), as long as they contained a description of wear measurement methodology. Only studies published after 1995 were considered.

RESULTS

After duplicates' removal, 495 studies were identified, and 41 remained for quantitative analysis. Thirty-four described wear-measurement protocols, using digital profilometry and superimposition, whereas 7 used alternative protocols. A specific form was designed to analyze the risk of bias. The methods were described in terms of material analyzed; study design; device used for surface acquisition; matching software details and settings; type of analysis (vertical height-loss measurement vs volume loss measurement); type of area investigated (entire occlusal area or selective areas); and results.

SINIFICANCE

There is a need of standardization of clinical wear measurement. Current methods exhibit accuracy, which is not sufficient to monitor wear of restorative materials and tooth tissues. Their performance could be improved, notably limiting the use of replicas, using standardized calibration procedures and positive controls, optimizing the settings of scanners and matching softwares, and taking into account unusable data.

A prospective 10-year follow-up dental cast study of patients with obstructive sleep apnoea/snoring who use a mandibular protruding device

Objectives

This 10-year prospective study aimed to measure and evaluate the teeth position and occlusion following 10-year nocturnal use of a mandibular protruding device (MPD) in subjects with obstructive sleep apnoea (OSA) or snoring.

Materials and methods

Seventy-seven consecutive patients diagnosed with OSA/snoring were treated with an MPD. Fabrication of dental casts with jaw registration indexes in the intercuspal position was carried out at baseline and at follow-up, a construction bite was made, and an MPD was fitted. At the 10-year follow-up, all subjects (n = 74) were invited to participate. The dental casts were analysed in a series of measurements.

Results

Sixty subjects were included in the follow-up examination-41 were still using the device and 19 had ceased using the MPD. The MPD users showed significant changes in all analysed variables-decrease of overjet (-1.8 mm), overbite (-1.5 mm)-except the mandibular intercanine width and the maxillary anteroposterior relationship. Subjects who had ceased using their MPD retained their initial values, with the exception of a decreased overbite. The MPD users also showed an increased number of subjects with mesio-occlusion and posterior infra-occlusion; those who had ceased using their MPD mostly retained their initial status.

Conclusions

Long-term nocturnal use of an MPD may cause both favourable and unfavourable occlusion changes, such as a decrease of the overjet and overbite or posterior infra-occlusion, and these changes may continue to develop during treatment with an MPD. Subjects with a Class III relationship may not be a suitable group for treatment with an MPD due to the mesial drift of the mandibular teeth.

Dimensional accuracy of jaw scans performed on alginate impressions or stone models: A practice-oriented study

OBJECTIVES

Digital jaw models offer more extensive possibilities for analysis than casts and make it easier to share and archive relevant information. The aim of this study was to compare the dimensional accuracy of scans performed on alginate impressions and on stone models to reference scans performed on underlying resin models.

METHODS

Precision spheres 5 mm in diameter were occlusally fitted to the sites of the first premolars and first molars on a pair of jaw models fabricated from resin. A structured-light scanner was used for digitization. Once the two reference models had been scanned, alginate impressions were taken and scanned after no later than 1 h. A third series of scans was performed on type III stone models derived from the impressions. All scans were analyzed by performing five repeated measurements to determine the distances between the various sphere centers.

RESULTS

Compared to the reference scans, the stone-model scans were larger by a mean of 73.6 µm (maxilla) or 65.2 µm (mandible). The impression scans were only larger by 7.7 µm (maxilla) or smaller by 0.7 µm (mandible). Median standard deviations over the five repeated measurements of 1.0 µm for the reference scans, 2.35 µm for the impression scans, and 2.0 µm for the stone-model scans indicate that the values measured in this study were adequately reproducible.

CONCLUSION

Alginate impressions can be suitably digitized by structured-light scanning and offer considerably better dimensional accuracy than stone models. Apparently, however, both impression scans and stone-model scans can offer adequate precision for orthodontic purposes. The main issue of impression scans (which is incomplete representation of model surfaces) is being systematically explored in a follow-up study.

Reliability of linear and angular dental measurements with the OrthoMechanics Sequential Analyzer

INTRODUCTION

The aim of this study was to evaluate the reliability of newly developed software in the assessment of orthodontic tooth movement 3 dimensionally.

METHODS

The sample consisted of pretreatment and posttreatment computed tomography scans and plaster dental models of 20 orthodontic patients treated with a hyrax palatal expander as a part of their comprehensive orthodontic treatment. Dental-arch measurements, including arch widths, tooth inclinations, and angulation parameters, were measured on the scans using InvivoDental 3D imaging software (version 5.1; Motionview, Hixson, Tenn). The plaster dental models were laser scanned and superimposed, and measurements were obtained digitally using the new software. Agreement between the digital models and the computed tomography measurements was evaluated with intraclass correlation coefficients, paired t tests, and Bland-Altman plots. A P value of ≤0.05 was considered statistically significant.

RESULTS

High agreement, a nonsignificant paired t test, and no indication of agreement discrepancies were observed for most of the measured parameters.

CONCLUSIONS

The results confirmed that the new software program offers a reliable tool for dental-arch measurements obtained from 3-dimensional laser-scanned models.

Model analysis in "8020" achievers using three-dimensional images

The purpose of this study was to clarify the effect of aging on the dentition by quantifying the dimensions of the dental arches in elderly persons aged over 80 years with 20 or more remaining teeth (8020 achievers). The study included twenty 8020 achievers (10 males and 10 females, with an average age of 82.3 years and an average of 28.3 present teeth). Their dental casts were digitized with a 3-dimensional (3-D) laser scanner, reconstructed into 3-D images, and measured with IMAGEWARE. The anterior and posterior widths of the upper and lower coronal arches and their anterior and posterior lengths together with the anterior and posterior widths of the maxillary and mandibular basal arches and their anterior and posterior lengths were measured. An unpaired t-test was performed using statistical analysis software. Dental models of 31 people with normal occlusion (16 males and 15 females, with an average age of 23.3 years) were measured with digital calipers and compared with the measurements obtained from the 8020 achievers. Several common items with significant differences were observed in the mandibular measurements. Each comparison indicated a tendency toward a decrease in size in the 8020 group: Coronal Arch P-length (p<0.05 in Male group, p<0.01 in Female group), Basal Arch A-width (p<0.05 in Male group, p<0.001 in Female group), Basal Arch A-length (p<0.001 in both group), and Basal Arch P-length (p<0.001 in both group). From these results, 3-D dental model analysis in twenty 8020 achievers revealed narrowing of the mandibular intercanine width and shortening of the mandibular anterior and posterior lengths.