Comparison of reliability, validity, and accuracy of linear measurements made on pre- and posttreatment digital study models with conventional plaster study models

[Degree of reliability of the assessment of the Bolton analysis in three-dimensional virtual models versus plaster models. a review]

Introduction

Bolton analysis is used to determine anomalies with respect to the dental mass, for diagnosis and treatment planning purposes, the possibility of using a digital method was introduced and tested to measure the size of the mesiodistal tooth. In this way, digital dental technology has made digital study models become popular in orthodontics.

Objective

to evaluate the degree of reliability of the evaluation of the Bolton analysis in three-dimensional virtual models versus plaster models through a review of the literature.

Materials and methods

A search was carried out in the primary databases of the international scientific literature on health sciences: Medline, through PubMed, SciELO, Lilacs, and Embase. Review articles published between the year 2000 and October 2021 were included.

Results

The desktop scanner was the best option for digitizing dental models, but this does not detract from CBCT and intraoral laser scanners, which are still an option. Reasonable validity for digitizing 3D models with results within the "clinically acceptable" range was found.

Conclusions

3D digital models generated with intraoral and extraoral scanners are reliable and accurate compared to conventional impressions and save time, in most cases statistically significant differences were found, but of little clinical relevance.

Comparison between stone and digital cast measurements in mixed dentition : Validity, reliability, reproducibility, and objectivity

Purpose

To assess the validity, reliability, reproducibility, and objectivity of measurements on stone casts of patients with mixed dentitions compared to measurements on three-dimensional (3D) digital models derived from surface scans of the stone casts.

Methods

Pairs of stone casts of 30 young patients in their mixed dentition stage were included and processed into 3D digital models using an intraoral scanner (iTero Element 2; Align Technology, San Jose, CA, USA). Then an experienced and an inexperienced examiner independently performed measurements of five defined parameters, each in triplicate, both on the digital models with analysis software (OnyxCeph3™; Image Instruments, Chemnitz, Germany) and on the original casts with a vernier calliper. Paired t-tests were used for validity and interexaminer objectivity, Pearson correlation coefficients for intermethod reliability, and intraclass correlation coefficients (ICCs) for reproducibility testing.

Results

Significant (p < 0.05) intermethod differences were identified for four parameters, but only the differences for overbite and intermolar distance exceeded the threshold of clinical relevance (≥ 0.5 mm). Intermethod reliability was high and method error invariably lower for the digital measurements and for the experienced examiner. Both examiners achieved ICCs > 0.907 with both methods. Interexaminer variation involved significant differences for all parameters but one (intermolar distance) on the stone casts and for three parameters on the digital models.

Conclusion

Measurements performed on digital models of mixed dentitions can yield clinically acceptable outcomes with OnyxCeph3™ software. Both the digital and the analogue measurements were highly reproducible and reliable. Objectivity of the measurements could not be confirmed, as operator experience did make a difference.

Three dimensional changes of maxillary arch in Unilateral cleft lip and palate patients following comprehensive orthodontic treatment on digital study models

OBJECTIVE:

To compare the effects of comprehensive orthodontic treatment on palatal area, volume, inter-canine and inter-molar width in patients with Unilateral Cleft Lip and Palate (UCLP) using scanned models of the maxillary arch.

DESIGN:

Retrospective cohort study.

SETTING:

Tertiary setting.

PATIENTS:

Two hundred and ten plaster study models of 70 patients with Unilateral Cleft Lip and Palate (Study group SG) and Control Group (n = 70) were scanned using Maestro 3D Dental scanner. The study groupwas further divided into subgroups; Subgroup I: treated with orthodontic treatment only (non-surgical), Subgroup II: patientsmanaged with combined orthodontics and orthognathic surgery (either maxillary advancement or maxillary distraction), Subgroup A: age >14 years and Subgroup B: age <14 years.

INTERVENTIONS:

Comprehensive orthodontic and Orthosurgical treatment

MAIN OUTCOME MEASURES:

Pre- and post-treatment scanned maxillary models of the study group were compared for palatal area and volumeand intercanine and intermolar width. The palatal dimensions of post-treatment scanned models were also compared to that of the control group.

RESULTS:

The Palatal area and volume, intercanine and intermolar width were significantly higher in the post-treatment as compared to pre-treatment study models (P < 0.01). The measurements ofthe maxillary arch were significantly higher in the control group compared to the post-treatment measurements of the study group. The increase in palatal area and volume was greater in Subgroup I and A compared to Subgroup II and B patients, respectively.

CONCLUSION:

The 3-Dimensional palatal dimensions in UCLP group improved after orthodontic treatment but were still not comparable to the normal subjects. The patients with age >14 years showed more improvement in the maxillary arch.

Mesiodistal dimensions of teeth in Serbian orthodontic patients with hypodontia

Introduction/Objective. Hypodontia is a common dental anomaly that occurs either in a non-syndromic form or as a part of various syndromes. It is considered a multifactorial condition with genetic, epigenetic and environmental influences, the interplay of which can lead to various anomalies in tooth size and number. The aim of this study was to assess mesiodistal tooth dimensions in Serbian hypodontia orthodontic patients and compare them to healthy controls using digital study models. Methods. Fifty subjects (30 females, 20 males) divided into two groups - 25 with hypodontia (15 females, 10 males) and 25 gender-matched controls (15 females, 10 males) were included in the study. Alginate impressions were taken and plaster models poured, digitized and imported into the software where mesiodistal dimensions were obtained. Results. Intra-operator reliability was high. All teeth in the hypodontia group had smaller mesiodistal dimensions compared to controls. Statistical significance was noted for all teeth except for upper canines. No statistically significant differences were found between males and females in neither the hypodontia nor the control group, except for lower canines, which were significantly smaller in both hypodontia and control females. The most commonly missing teeth were upper lateral incisors, and lower and upper premolars. Conclusion. Hypodontia group presented with smaller mesiodistal dimensions compared to controls. The greatest difference in mesiodistal dimensions was found in upper lateral incisors and lower first molars. Lower canines were significantly larger in males compared to females in both groups.

The step further smile virtual planning: milled versus prototyped mock-ups for the evaluation of the designed smile characteristics

BACKGROUND

Mock-up based approach allows the preview of the aesthetic rehabilitation, however, it is crucial that the mock-up does not differ from the expected aesthetic outcomes. With CAD-CAM technologies, it is possible to directly create mock-ups from virtual planned smile project, with greater accuracy and efficiency compared to the conventional moulded mock-ups. In this study, we investigated the trueness of mock-ups obtained with milling and 3D printing technology and a full digital work-flow system.

METHODS

Ten adults subjects were included and digital smile design/digital wax-up were performed to enhance the aesthetic of maxillary anterior region. Ten milled mock-ups and 10 prototyped mock-ups were obtained from the original .stl file and a digital analysis of trueness was carried out by superimposing the scanned-milled mock-ups and the scanned-prototyped mock-ups to the digital wax-up, according to the surface-to-surface matching technique. Specific linear measurements were performed to investigate and compare the dimensional characteristics of the physical manufactures, the 3D project and the scanned mock-ups. All data were statistically analyzed. A clinical test was also performed to assess the fitting of the final manufacture.

RESULTS

The prototyped mock-ups showed a significant increment of the transversal measurements (p < 0.001) while the milled mock-ups showed a significant increment of all vertical and transversal measurements (p < 0.001). The prototyped mock-ups showed good fitting after clinical tests while none of the milled mock-ups showed good adaptation (no fitting or significant clinical compensation required). Deviation analysis from the original 3D project reported a greater matching percentage for the scanned-milled mock-ups (80,31% ± 2.50) compared to the scanned-prototyped mock-ups (69,17% ± 2.64) (p < 0.001). This was in contrast with the findings from linear measurements as well as from the clinical test and may have been affected by a reductive algorithmic computation after digitization of physical mock-ups.

CONCLUSION

Both prototype and milled mock-ups showed a slight dimensional increment comparing to the original 3D project, with milled-mock-ups showing less fitting after clinical tests. Caution must be taken when assessing the trueness of scanned manufacture since an intrinsic error in the system can underestimate the dimensions of the real object.

3-Dimensional prediction of pre-surgical decompensation after atypical extractions and soft tissue simulation for ortho-surgical management of skeletal Class III malocclusion: A case report

Three dimensional imaging systems whether in the form of digital models, facial scanning or dolphin software play an important role in proper diagnosis and treatment planning of the orthosurgical cases. This case report highlights importance of three-dimensional treatment planning in the ortho-surgical management of the patient with skeletal Class III malocclusion involving atypical extraction. On clinical examination, patient had concave profile, prominent chin, deficient midface, flat cheekbone contour and prominent nasal projection. He had Class III molar and canine relation bilaterally with missing 12 (previously extracted), negative overbite and overjet with discordant maxillomandibular midlines. After 3-dimensional digital model set-up for occlusion planning and dolphin simulation for soft tissue prediction, extraction of left maxillary lateral incisor was planned followed by maxillary advancement and mandibular setback surgery and finish the occlusion in Class II molar relationship. After the orthodontic and orthognathic surgical treatment, the skeletal and dental imbalance was corrected, and most of the treatment objectives were achieved and patient was extremely satisfied with his facial profile. The treatment results were stable at the 3 years follow-up.