Local factors relating to mandibular canine impaction: A retrospective study.

INTRODUCTION: This study aimed to investigate the characteristics of impacted and transmigrated mandibular canines and the association existing between them and some local factors, such as degrees of axial inclination of mandibular incisors, skeletal Class, and mandibular symphysis width. METHODS: A retrospective observational study was performed on the medical records and radiographic examination (panoramic radiographs and lateral cephalograms) of 102 orthodontic patients divided into a study group, with at least 1 impacted mandibular canine (51 subjects) and a control group, without mandibular impaction (51 subjects). A chi-square test, t test, and analysis of variance test analysis were used to analyze the data. RESULTS: Unilateral and buccal impaction and the presence of the deciduous canine were the more prevalent characteristics of impacted canines, whereas 39.2% presented transmigration. Furthermore, the persistence of the deciduous canine on the impaction side (P <0.0001) and the mesial axial inclination of the impacted canine (P <0.0001) were found to be statistically significant characteristics. A statistically significant association was found between the impaction of the mandibular canine and mandibular incisor to the mandibular plane angle (IMPA) (IMPA, 95.8°; P = 0.009). An additional statistically significant association was found with transmigrated canines (IMPA, 96.8°; P = 0.024). CONCLUSIONS: The mesialization of the canine cusp and the persistence of the mandibular deciduous canine are characteristics frequently found in the impaction of the mandibular canine. An accentuated vestibular inclination of the mandibular incisors is significantly associated with mandibular canine impaction.

Accuracy Of Imaging Software for 3d Rendering of Tooth Structures, Usable in Clinical Settings.

AIM: The aim of this study was to evaluate the segmentation accuracy of dentition testing four free-source semi-automatic software. MATERIALS AND METHODS: A total of 20 cone-beam computed tomography (CBCT) were selected to perform semi-automatic segmentation of maxillary and mandibular dentition. The software tested were Invesalius, ITK-Snap, 3D Slicer and Seg3D. Each tooth model was also manually segmented (Mimics software) and set as the gold standard (GS) reference of the investigation. A specific 3D imaging technology was used to perform the superimposition between the teeth models obtained with semi-automatic software and the GS model, and to perform the surface-to-surface matching analysis. The accuracy of semi-automatic segmentation was evaluated calculating the volumetric mean differences (mean bias and limits of agreement) and the percentage of matching of the tooth models compared to the manual segmentation (GS). Qualitative assessments were performed using color-coded maps. All data were statistically analysed to perform software comparisons. RESULT: Statistically significant differences were found in the volumetric and matching percentage data (p < 0,05). Invesalius was the most accurate software for 3D rendering of the dentition with a volumetric bias (Mimics) ranging from 4,59 mm3 to 85,79 mm3; instead, ITK-SNAP showed the higher volumetric bias, ranging from 30,22 mm3 to 319,83 mm3. The dis-matched area was mainly located at the radicular region of the teeth. Volumetric data showed excellent inter-software reliability with coefficient values ranging from 0,951 to 0,997. CONCLUSIO: Different semi-automatic software algorithms could generate different patterns of inaccuracy error in the segmentation of teeth.

Periodontal results of different therapeutic approaches (open vs. closed technique) and timing evaluation (< 2 year vs. > 2 year) of palatal impacted canines: a systematic review.

BACKGROUND: This review evaluates, as a primary outcome, which surgical technique (open vs. closed) and which type of material used for the auxiliaries (elastic vs. metallic) were preferable in terms of periodontal results during the treatment of palatal-impacted canines. The timing of the evaluation of the results was also assessed as a secondary outcome. METHODS: An electronic search of the literature up to March 2021 was performed on Pubmed, MEDLINE (via Pubmed), EMBASE (via Ovid), Cochrane Reviews and Cochrane Register of Controlled Trials (RCTs) (CENTRAL). The risk of bias evaluation was performed using version 2 of the Cochrane risk of bias tool (RoB 2) for RCTs and the ACROBAT NRSI tool of Cochrane for non-RCTs. RESULTS: 11 articles met the inclusion criteria. Only one RCT was assessed as having a low risk of bias and all the non-RCTs were assessed as having a serious risk of bias. This review revealed better periodontal results for the closed technique and metallic auxiliaries. In addition, it revealed that the timing of the evaluation of the results affects the periodontal results with better results obtained 2 years after the end of treatment. CONCLUSION: In the treatment of a palatal-impacted canine, the closed technique and metallic auxiliaries should be preferred in terms of better periodontal results. The timing of the evaluation of the results affects the periodontal results.

Computer-guided palatal canine disimpaction: a technical note.

AIM: To present a minimally invasive approach to solve the impaction of palatal canines using computer-guided orthodontic miniscrews. MATERIALS AND METHODS: Miniscrew-supported appliances for palatal canine disimpaction are performed with CAD/CAM technology. With adequate software, it is possible to match the STL files of the dental arch with the DICOM images of the maxilla, previously transformed into STL files. The ideal points for miniscrew insertion can be identified on the STL 3D model file on the basis of the width and thickness of the palatal vault. A software application allows for the design of the surgical guide, which is printed using a 3D printer. The virtual position of the planned miniscrews is transferred onto a printed dental cast on which the orthodontic device is realized. On the day of surgery, both the surgical guide and the orthodontic appliance are ready for use. RESULTS: Miniscrew insertion and palatal canine disimpaction can be achieved in one surgical procedure. CONCLUSION: The use of computer-guided skeletal anchorage allows for both the reduction of the biomechanical side effects typical of conventional treatment and the risk of damaging adjacent anatomical structures, increasing the effectiveness of treatment. Controlled clinical trials are necessary to evaluate more fully any advantages of this minimally invasive technique.

Orthodontic-Orthopedic-Surgical Treatment of Syndromic Third Class: Proposal of a New Craniofacial Cephalometric Method.

The management of patients suffering from class III due to syndromic craniosynostosis requires a multidisciplinary team to prevent and correct the complex clinical features related to the syndrome. Among the main clinical features, the midface hypoplasia requires surgical advancement with a rigid external distraction device. The comparison of pre- and postdistraction lateral cephalometries is often difficult in these patients, because the craniofacial advancement mobilizes the landmarks routinely used in cephalometry. Aim of this study is to evaluate occlusal, maxillary, and facial changes obtained after the midface osteodistraction using as reference the PM plane, that does not undergo postsurgical spatial modifications.The before and after surgery lateral X-rays of 12 patients were compared to test the cephalometric protocol: 10 angles and 11 linear distances were evaluated.The cephalometric comparison before and after osteodistractions of syndromic class III, using as reference the Enlow's PM plane, has confirmed the data present in current literature, consisting in forward and downward movements of facial middle 3rd, with clockwise rotation of the splanchnocranium and increase of the facial heights. The use of the PM plane as reference could be the solution to problems that have been an obstacle for the study of occlusal and facial changes in patients affected by craniofacial dysostosis.

Three-dimensional evaluations of the digital casts of morphologic maxillary teeth symmetry in patients with unilateral palatally displaced canines.

INTRODUCTION: The goal of this study was to compare the size and morphologic symmetry of the maxillary teeth in subjects with and without unilateral palatally displaced canines (PDCs). METHODS: Plaster casts of 38 subjects (mean age 14.75 ± 0.95 y) with unilateral PDCs were selected (study group [SG]) and compared with casts from an age- and sex-matched control group (CG). Then dental casts of both groups were scanned into 3-dimensional (3D) models. Tooth sizes (mesiodistal [MD] and buccolingual [BL] widths and volumes) for SG and CG were measured. Afterward, 3D deviation analysis was carried out with the use of Geomagic Control X software. All of the data were normally distributed according to parametric tests. RESULTS: All of the maxillary tooth diameters were smaller in SG than in CG. Statistically significant differences (P ≤ 0.001) were obtained when comparing the widths and volumes of the PDC quadrant and the unaffected quadrant of the same patient. Morphologic tooth symmetry by surface-to-surface matching for SG (PDC side vs non-PDC side) and CG (right vs left quadrant) demonstrated significant (P ≤ 0.001) but small differences, except for the lateral upper incisors (71.27%). CONCLUSIONS: Unlike control subjects, PDC patients showed high mismatching of lateral incisor crowns of ∼30%.

Epidemiology of Malocclusion in 3,491 Subjects Attending Public Dental Service in Rome (Italy): Evaluation of the Orthodontic Treatment Need Index.

AIM: The objective of this epidemiological survey is to investigate the dental-skeletal features of subjects attending the Public Dental Service in Unità Operativa Complessa (UOC) (Orthodontic Department of "La Sapienza University of Rome") and compare them with the existing body of evidence obtained from other surveys. Accordingly, the Index of Orthodontic Treatment Need (IOTN) was employed, in order to achieve a common framework to allow the shaping of public health prevention practices. MATERIALS AND METHODS: A sample of 3,491 subjects in the Orthodontic Department of "La Sapienza-University of Rome" (UOC) was evaluated with the adoption of IOTN to define malocclusion severity. RESULTS: In the result analysis, it was observed that class II malocclusion was more frequent in the sample (40%), and a large part of the examined population also presented mandibular dental crowding (43%), increased overjet (41%), and increased overbite (38%). Only 26.44% (20.17% IOTN 4; 6.27% IOTN 5) had strong need for orthodontic treatment. CONCLUSION: The realization of epidemiological investigations to establish priority for treatment need is, therefore, particularly useful, not only to estimate the prevalence of some clinical conditions in the observed population, but also to plan targeted interventions, such as interceptive and corrective therapies in growing children. CLINICAL SIGNIFICANCE: These interventions could solve specific clinical situations and/or prevent their escalation. Only in this way, it is possible to avoid fragmentation of the limited resources available, using them for patients with an objective need.

Three-dimensional evaluation on digital casts of maxillary palatal size and morphology in patients with functional posterior crossbite.

Background and objectives: Some authors have recently postulated the possibility of a unilateral contraction of the palate in patients with crossbite. This study aimed to investigate palatal dimension size and morphology in subjects with functional posterior crossbite and to localize location of the contraction through a 3D analysis procedure. Materials and methods: A study sample (SS) of 35 subjects (mean age 9.2 ± 0.8 years), diagnosed with functional crossbite, and a control sample (CS) of 35 subjects (mean age 9.4 ± 0.9 years) without crossbite were selected for this study. The digital models of each patient were analysed to assess palatal dimension size and symmetry by measuring linear distances between primary canines (D1) and fist molars (D2) to the median palatine plane and by performing and analysing the 3D deviation between the two specular models of the palatal vault for each patient. Results: Our findings demonstrate a significantly narrower dimension of D2 for the crossbite side than at the non-crossbite side. The 3D deviation analysis demonstrates a lower matching percentage of the palatal vault models in the SS (83.36%) compared with the CS (92.82%) and a location of that the palatal contraction is at the alveolar bone level. Conclusions: It can be assumed that there is a bilateral symmetrical contraction of the palatal vault and an asymmetric contraction of the alveolar process, but further studies are needed to corroborate this hypothesis.

Alveolar bone changes after rapid maxillary expansion with tooth-born appliances: a systematic review.

Background: During rapid maxillary expansion (RME), heavy forces are transmitted to the maxilla by the anchored teeth causing buccal inclination and buccal bone loss of posterior teeth. Objective: To systematically review the literature in order to investigate whether RME causes periodontal sequelae, assessed by cone-beam computed tomography (CBCT). Search methods: Fifteen electronic databases and reference lists of studies were searched up to March 2017. Selection criteria: To be included in the systematic review, articles must be human studies on growing subjects, with transversal maxillary deficiency treated with RME and with assessment of buccal bone loss by CBCT images. Only randomized and non-randomized trials were included. Data collection and analysis: Two authors independently performed study selection, data extraction, and risk of bias assessment. Study characteristics (study design, sample size, age, sex, skeletal maturity, type of appliance, daily activation, evaluated linear measurements, observation period, CBCT settings), and study outcomes (loss of buccal bone thickness and marginal bone) were reported according to the PRISMA statement. Results: On the basis of the applied inclusion criteria, only six articles, three randomized clinical trials and three controlled clinical trials were included. An individual analysis of the selected articles was undertaken. The risks of bias of the six trials were scored as medium to low. Limitations: The results of the present systematic review are based on a limited number of studies and only one study included a control group. Conclusions and implications: In all considered studies, significant loss of buccal bone thickness and marginal bone level were observed in anchored teeth, following RME. Further prospective studies correlating the radiological data of bone loss to the periodontal soft tissues reaction after RME are required. A preliminary evaluation of the patient-related risk factors for RR may be advisable when considering to administering RME. Registration: This systematic review was registered in the National Institute of Health Research database with an appropriate protocol number (http://www.crd.york.ac.uk/PROSPERO Protocol: CRD42017062645). Funding: The present study has not received any contributions from private or public funding agencies.

The Use of CAD/CAM Technology in Mandibular Canine Disimpaction: A Case Report.

This case report of an 11-year-old subject shows the digital workflow for the management of an impacted mandibular canine using Computer-Aided Design/Computer-Aided Manufacturing (CAD/CAM) technology along with Temporary Anchorage Devices (TADs). The miniscrew insertion site was planned using software, and a surgical guide was digitally designed and 3D printed. Orthodontic traction was performed using a 3D-designed and -printed device. In a single sitting, the miniscrew was inserted and the disimpaction device was also delivered. The primary objective of recovery and the repositioning of the impacted mandibular canine in the axis with its eruptive path was achieved. The space available and the subject's early stage of mixed dentition was considered favourable to a spontaneous eruption. This case report shows how CAD/CAM digital technology, combined with 3D printing, enables the creation of a surgical guide to position the miniscrew and the customized devices used for mandibular canine disimpaction. CAD/CAM surgical guides can help clinicians to position TADs with more accuracy and predictability, ensuring high quality bone support offering primary stability. Although orthodontic traction is the most complex therapeutic choice to implement, with the aid of CAD/CAM technology it is possible to proceed with accurate and minimally invasive orthodontic traction in order to recover a mandibular canine.

Impaction of permanent mandibular second molar: a retrospective study.

OBJECTIVE: To determine the prevalence of impacted mandibular second molar (MM2) and the association between MM2 impaction and crowding. The clinical significance of the angle between first and second mandibular molar and of the space between the first mandibular molar (MM1) and the anterior margin of mandibular ramus in MM2 impaction were also evaluated. MATERIAL AND METHODS: In this retrospective study , from the dental records of 2,945 caucasian young orthodontics patients , 40 subjects with MM2 impaction were included in a study group (SG) and compared with a control group (CG) of 200 subjects without MM2 impactions. The crowding , the angle of inclination of MM2, the distance between MM1 and mandibular ramus, the canine and molar relationships, and the lower centre line discrepancy were measured. For the statistical analysis , descriptive statistics and t-Student for independent sample groups were used. RESULTS: The prevalence of impacted MM2 was 1.36%. The independent-Samples t-Test between SG and CG showed: the presence of crowding (P ≤ 0.001), an higher angle values of MM2 inclination (P ≤ 0.001) and a smaller distance between MM1 and the anterior margin of mandibular ramus (P ≤ 0.001) in the SG. CONCLUSION: The impaction of MM2 is a relatively rare occurrence in orthodontic caucasian populations. The crowding, a higher angle values of MM2 inclination and a reduced distance between MM1 and the anterior margin of mandibular ramus, at the time of one third of MM2 root formation (T1), characterize MM2 impaction.

Skeletal features in patient affected by maxillary canine impaction.

OBJECTIVE: To analyze the skeletal features of patients with maxillary canine impaction. MATERIAL AND METHODS: The complete pre-treatment records of 1674 orthodontic patients were examined. From the subjects with maxillary impacted canine 12 patients were excluded , remaining 108. The subjects with maxillary impacted canine were divided into two study groups: a palatally displaced canine group (PDCG) (77 patients) and a buccally displaced canine group (BDCG) (31 patients). The values of the skeletal features measured on the lateral cephalometric radiograph were compared with a control group (CG) of 121 subjects randomly selected from the initial sample without maxillary canine impaction. The statistical analysis of the difference between the study groups and the CG was tested using χ(2) test and Fisher's exact test. The level of significance was set at P ≤ 0.05. RESULTS: The CG was characterized by increased values of sella- nasion- A point angle (ANB) and by a retro-positioned or smaller lower jaw. PDCG patients showed normal skeletal features compared to the CG, presenting mainly I class and lower rank of II and III sagittal skeletal features. PDCG subjects presented also normal values of the Steiner vertical skeletal relationship angles with normal facial divergence compared to the CG. PDCG cases were also characterized by horizontal and prognathic growth. BDCG did not present significant differences in skeletal features compared to the CG, except for an increased ANB. CONCLUSIONS: Palatally displaced canine (PDC) was frequently the only orthodontic problem of patients and was not associated whit altered skeletal features. The frequent absence of malocclusion in PDC patients explains the delayed identification of this problem. BDCG patients did not present significant differences in skeletal features with respect to the orthodontic population (CG). The presence of both buccally displaced canine (BDC) and malocclusion makes the patient with BDC both aware of the need for, and motivated to undergo, orthodontic treatment.

Can computer-guided surgery help orthodontics in miniscrew insertion and corticotomies? A narrative review.

Orthodontics has considerably increased the use of technology combined with surgery as a tool to improve dental movements in terms of predictability, acceleration of movement, and fewer side effects. To achieve these goals miniscrews and corticotomy were introduced. The digital workflow permits an increase in the accuracy of surgical and orthodontic setups. The tool that transfers the information is the CAD/CAM (Computer-Aided Design/ Computer-Aided Manufacturing) template. The aim of this review is to illustrate the use of computer-guided surgery in orthodontics regarding miniscrews and piezocision. The search strategy was a combination of Medical Subject Headings (Mesh) and free text words for PubMed. A total of 27 articles were included in this review: 16 concerned miniscrews and 11 concerned corticotomy. The current need for faster treatments, the improved systems of anchorage, and the evolution of imaging technologies require operators to be knowledgeable of the digital workflow. CAD/CAM templates allow greater precision and predictability of miniscrew insertion even if in the hands of less experienced clinicians and permit a better orientation and depth of the cortical incision. In conclusion, digital planning makes surgery faster and easier and allows for the identification and correction of any potential problem before the procedure.

Dental and skeletal features in subjects with missing maxillary lateral incisors: a case control retrospective study.

BACKGROUND: The aim of this study was to investigate the relationship between missing maxillary lateral incisors and the mesio-distal (MD) diameters of the teeth. Occlusal and skeletal characteristics of the patients have been analyzed. METHODS: Seventy-nine patients were included in the study (permanent dentition, mean age: 13.7): 30 subjects with uni- or bilateral maxillary lateral incisors agenesis (study group, SG) and 49 patients with no maxillary lateral incisors agenesis (control group, CG). Orthopanoramics, plaster models and cephalometric analysis were used to perform the evaluations. RESULTS: Compared to the CG, in the SG, most of the teeth had smaller MD diameter. In the bilateral agenesis subgroup, the average differences between teeth diameters were lower than those found by comparing them to the unilateral agenesis subgroup and to the SG. Overjet was reduced on average in the SG. In the SG were found less cases of cross-bite and scissor-bite, less frequency of impaction of at least one tooth and agenesis of other teeth, crowding only in the lower arch, square or ovoid arch shape in the upper arch and square in the lower arch, increased interincisal angle and decreased SN^GoMe. CONCLUSIONS: Upper lateral incisors agenesis, especially in cases of unilateral agenesis, is associated with MD teeth reduction. The agenesis of the upper lateral incisors is associated with a greater probability of agenesis affecting other teeth, molar and canine class II, reduced overjet and overbite, square or ovoid upper arch shapes, increased interincisal angle and reduced total divergence.

Enamel Analysis by 3D Scanning after Three Orthodontic Clean-Up Procedures: An In-Vitro Test of a New Piezoelectric Tool.

(1) Background: To assess the clinical safety and efficacy of a new piezoelectric instrument for orthodontic clean-up; (2) Methods: An in-vitro comparative study on 75 teeth extracted for orthodontic reasons compared the tested method (Treatment 1) with two other procedures: One step finisher and polisher (Inverted cone One gloss Shofu Dental, Kyoto, Japan) (Treatment 2) and twelve-fluted tungsten carbide bur (123-603-00, Dentaurum, Pforzheim, Germany) and Sof-Lex discs Pop-On XT Kit (3M ESPE) (Treatment 3), with n:25 samples in each group. Clinical safety (enamel volume loss) and effectiveness (residual adhesive volume) were assessed using the structured light 3D scanner Atos Compact Scan (GOM GmbH) together with the support of Atos Professional software. The surfaces were scanned three times to assess: (i) the volume of the residual adhesive (RAV) after bracket removal; (ii) the volume of the relative residual adhesive (dAV) after the clean-up procedure; (iii) volume of the enamel loss (EVL); (3) Results: The mean RAV (mm3) was 0.239 ± 0.337; 0.069 ± 0.124, 0.120 ± 0.193 and the mean EVL (mm3) was 0.1870 ± 0.177, 0.187 ± 0.299 and 0.290 ± 0.205, for treatment 1, 2 and 3, respectively. The distribution was asymmetrical between groups in both cases; (4) Conclusions: The tested instrument proved to be effective and safe for post-orthodontic clean-up. With the increasing use of invisible aligners, the possibility of using an ergonomic and fast instrument is of benefit to both patient and practitioner.

Factors affecting duration of post-surgical orthodontics in the Surgery First/Early Approach: A retrospective study.

BACKGROUND: Surgery First Approach (SFA) and Surgery Early (SE) are considered promising alternatives, compared to the conventional three-stages orthodontic-surgical approach, for treatment of dento-maxillofacial deformities. However, many features need further study, like the role of the orthodontist. Aim of the study was to analyse the clinical characteristics of patients who underwent SFA and SE, and if differences in duration of orthodontics could be influenced by clinical features. METHODS: A retrospective research was performed on patients who met the inclusion criteria for SFA (31) and SE (12), of the total of patients affected by dento-facial deformities in our Unit (191) in the period 2012-2017. After collection of clinical data, duration of orthodontics, age, pre-treatment PAR Index, ANB angle, amount of the curve of Spee were compared. A regression analysis evaluated if these clinical parameters, together with type of bracket and type of intervention, could influence the duration of post-surgical orthodontics. RESULTS: All patients who performed the SFA/SE were affected by class III, II and active Unilateral Condylar Hyperplasia (22% of total population). Pre-treatment mean differences of age (p = 0.0518), PAR Index (p = 0.0916), curve of Spee (p = 0.1006) between groups were not statistically significant. A statically significant difference was found for the overall duration of therapy, for the significant shorter duration of pre-surgical orthodontics, while the difference of post-surgical orthodontics duration was not significant (p = 0.4753). Type of bracket (rho=-0.19039, p = 0.266) and intervention performed (rho=-0.11522, p = 0.5034) were not correlated with duration of post-surgical orthodontics, as well as pre-treatment PAR Index, ANB angle and depth of the curve of Spee. CONCLUSIONS: Surgery First/Early Approach is a therapeutic choice that could be performed only in patients affected by specific malocclusions and who exactly meet indications. Protocol and post-surgical occlusal stability are factors that should influence the duration of therapy more than clinical characteristics.

Efficacy and Accuracy of Maxillary Arch Expansion with Clear Aligner Treatment.

The aim of this work was to evaluate the efficacy and accuracy of maxillary arch transverse expansion using the Invisalign® clear aligner system without auxiliaries other than Invisalign attachments. Knowing the accuracy of a movement through a clear aligner system allows the clinician to plan the treatment with greater precision and to achieve the expected result faster. The study group included 28 patients with a mean age of 17 ± 3.2 years. The treatment protocol for all the selected patients included the application of the Invisalign® clear aligner system without auxiliaries, except for the Invisalign® attachments; in no case were tooth extraction or interproximal enamel reduction (IPR) performed. Linear measurements of the expansion were assessed before treatment (T0), at the end of treatment (T1), and on final virtual models by ClinCheck® (TC). A paired t-test was used to compare T0-T1 and T1-TC differences. A paired t-test was applied, and one normality was validated with the Shapiro-Wilks test. If normality was not met, the nonparametric test (Mann-Whitney U test) was applied. The level of significance was set at 5%. Statistically significant differences were found for all measurements at T0-T1. The results showed an average accuracy of efficacy of 70.88%. The differences in predictability between the various vestibular measurements (intercanine, inter-premolar, and intermolar) were not statistically significant, while they were for gingival measurements. The overall accuracy of the expansion treatment was 70%, regardless of tooth type.

Evaluation of nasal airway resistance in a cohort of children with primary snoring and maxillary deficiency.

BACKGROUND: The aim of this study was to test whether rapid palatal expansion is effective to improve nasal airway patency in a sample of pediatric patients with primary snoring. METHODS: A group of 21 subjects, 11 girls (52%) and 10 boys (48%), with a mean age of 7.1 years (SD=1.3; range 4-9 years) were treated with a rapid maxillary expansion (RME) device. Nasal airway resistance was assessed via rhinomanometric exam before (pre-) and 6 months after (post-) the rapid palatal expansion treatment. RESULTS: Data analysis showed a statistically significant increase in the mean scores of the results of the rhinomanometric exam between the pre- and post-measurements with a significant reduction in total inspiratory and expiratory air resistance values after rapid palatal expansion. CONCLUSIONS: Our results show that RME treatment is associated with an improvement in nasal airway resistance due to a substantial reduction in nasal resistance associated with the orthopedic action of the orthodontic device.

Accuracy of orthodontic models prototyped for clear aligners therapy: A 3D imaging analysis comparing different market segments 3D printing protocols.

OBJECTIVES: This study aimed to evaluate the accuracy of orthodontic models for the production of clear aligners generated with four 3D printers featuring different technologies and belonging to different market segments. MATERIALS AND METHODS: Eighty identical dental models were generated from two master digital files (.stl), respectively with aligned (AM group) and crowded dentition (CM group), and prototyped via four different 3D printers, i.e., Asiga Pro 4K65 (DLP technology, high-professional segment), Elegoo Mars Pro (LCD technology, entry-level segment), Form 3B (SLA technology, medium-professional segment) and Vector 3SP (SLA technology, industrial segment). Each 3D printed model was scanned and superimposed with the master file, and deviation analysis was used to evaluate trueness and precision (root mean square values). All data were statistically analyzed (p < 0.05). RESULTS: The trueness error was lower in models prototyped with SLA printers compared to the LCD/DLP printers (p < 0.001); models prototyped with Elegoo Mars Pro-showed higher precision error compared to the other printers (P < 0.001). The models in the CM group showed higher trueness error compared to AM group when prototyped with LCD/DLP printers (p < 0.001). Accuracy error values were within the accepted clinical error for producing clear aligners (< 0.25 mm), with the entry-level 3D printer almost reaching this value. CONCLUSION: The accuracy of orthodontic models generated for clear aligners can be influenced by different technologies/market segments of the 3D printers used. CLINICAL RELEVANCE: Caution should be taken with entry-level 3D printers for producing clear aligners.