Assessment of condylar volume and ramus height in JIA patients with unilateral and bilateral TMJ involvement: retrospective case-control study

Positional, morphologic, and volumetric differences in TMJ in unilateral posterior crossbites and controls: A retrospective CBCT study

OBJECTIVES

The objective of this study was to evaluate if there are any morphologic, positional, and volumetric differences in the temporomandibular joint (TMJ) of patients with unilateral posterior crossbite (UPC) compared to controls. Another objective was to analyse the discrepancy in the TMJ between the crossbite versus non-crossbite side in UPC versus right and left sides in controls. Additionally, this study aimed to evaluate the differences in the bone density at the masseteric insertion site at the angle of mandible in the UPC group and control group.

MATERIAL AND METHODS

One hundred and thirty-two CBCTs were analysed with 66 patients in UPC group and 66 patients in control group (non-crossbite). Temporomandibular joint spaces - Anterior joint space (AJS), Superior joint space (SJS), Posterior joint space (PJS), Medial joint space (MJS), Middle joint space (MiJS), and Lateral joint space (LJS) were measured. Additionally, bone density at angle of mandible and volume of mandibular condyle were evaluated. The measurements were compared between the groups as well as between the crossbite and non-crossbite sides within the UPC group and between right and left sides within the control group. Furthermore, the associations between UPC and changes in TMJ regarding joint space availability, bone density, condylar head volume, and the effects of sex and age were evaluated using regression analysis.

RESULTS

It was observed that UPC group showed a greater condylar volume, than the control group. Additionally, a larger mean discrepancy was observed between the crossbite side and non-crossbite side within the UPC group concerning condylar volume than controls. Concerning age, condylar volume was observed to be larger in adults than children. Adults showed significantly greater bone density and condylar volume than adolescents. Concerning sex, it was observed that males showed a larger SJS (right), MiJS, LJS, and bone density at the mandibular angle than females.

CONCLUSION

There is a difference in the TMJ parameters particularly condylar volume in patients with UPC compared to controls.

Temporomandibular Joint Space in Mandibular Prognathism

This study compared the temporomandibular joint (TMJ) space between patients with normal and prognathic mandibles. The study included a total of 68 Korean individuals, and the TMJ space was measured using computed tomography. Patients with normal SNB values (normal mandible) were classified into Group 1. Patients with high SNB values (prognathic mandibles) were categorized into Group 2. The TMJ space was defined as the distance between the condylar process and the mandibular fossa, and it was significantly different between Groups 1 and 2 (1.94±0.07 mm versus 1.50±0.05 mm, P<0.01). This study confirmed that the TMJ space in patients with prognathic mandibles is narrower than that in patients with normal mandibles.

Suggestion of a new standard in measuring the mandible via MRI and an overview of reference values in young women

PURPOSE

Adult idiopathic condylar resorption (AICR) mainly affects young women, but generally accepted diagnostic standards are lacking. Patients often need temporomandibular joint (TMJ) surgery, and often jaw anatomy is assessed by CT as well as MRI to observe both bone and soft tissue. This study aims to establish reference values for mandible dimensions in women from MRI only and correlate them to, e.g., laboratory parameters and lifestyle, to explore new putative parameters relevant in AICR. MRI-derived reference values could reduce preoperative effort by allowing physicians to rely on only the MRI without additional CT scan.

METHODS

We analyzed MRI data from a previous study (LIFE-Adult-Study, Leipzig, Germany) of 158 female participants aged 15-40 years (as AICR typically affects young women). The MR images were segmented, and standardized measuring of the mandibles was established. We correlated morphological features of the mandible with a large variety of other parameters documented in the LIFE-Adult study.

RESULTS

We established new reference values for mandible morphology in MRI, which are consistent with previous CT-based studies. Our results allow assessment of both mandible and soft tissue without radiation exposure. Correlations with BMI, lifestyle, or laboratory parameters could not be observed. Of note, correlation between SNB angle, a parameter often used for AICR assessment, and condylar volume, was also not observed, opening up the question if these parameters behave differently in AICR patients.

CONCLUSION

These efforts constitute a first step towards establishing MRI as a viable method for condylar resorption assessment.

Volumetric analysis of normal condyles and those with disc displacement with reduction in the Indonesian population: A CBCT study

Purpose

Disc displacement can cause resorption of the head of the condyle and affect its volume. This study analysed the volume of normal condyles and those with disc displacement with reduction (DDR) in cone-beam computed tomography (CBCT) scans from the Indonesian population.

Materials and Methods

This study analysed 56 condyles (26 normal and 30 with DDR) from patients who visited the Oral and Maxillofacial Radiology Unit after being referred from the Prosthodontics Unit at Dental Hospital Universitas Padjadjaran from December 2020 to February 2021. Samples were divided into 2 groups (normal and DDR left and right-side condyles) based on the DC/TMD Axis 1 form through the clinical examination results. Both sample groups were exposed to CBCT radiation. The CBCT imaging results in the Digital Imaging and Communications in Medicine format were exported to the open-source ITK-SNAP format to determine condyle volume. Volumetric data from the cortical and trabecular areas of the right or left side condyles were arranged by sex. The independent t-test was used to determine the significance of differences with IBM SPSS version 21.0. Intra- and inter-observer reliability and validity were tested before determining the volume of the condyles.

Results

Normal condyles and DDR condyles showed significant differences in volume (P<0.05). Significant differences were also seen in cortical (P=0.0007) and trabecular (P=0.0045) volumes. There was a significant difference in condylar volume based on sex.

Conclusion

The normal condyle volume was significantly different from the DDR condyle volume in both sexes.

Short term effects of rapid maxillary expansion on breathing function assessed with spirometry: A case-control study

BACKGROUND

The aim of this work is to evaluate changes following rapid maxillary expansion (RME) on breathing function in two groups of patients: mouth breathers and nasal breathers.

MATERIALS AND METHODS

Twenty-five oral breather patients (12 male, 13 female, mean age 15.2 ± 1.3), and 25 nasal breather patients (14 male, 11 female, mean age 15.3 ± 1.6) were treated with RME. Breathing function was evaluated by computerized spirometry. Forced vital capacity (FVC), forced expiratory volume in the first second (FEV1), Tiffenau index (FEV1/ FVC ratio, IT%), forced expiratory flow at 25-75% of vital capacity (FEF 25-75%), and Tidal volume (TV) were assessed. Breathing function analysis was performed before RME and 6 and 12 months after RME during follow-up appointments. The Shapiro-Wilk test was used to assess whether data were normally distributed. As data were not normally distributed, Mann-Whitney U and Friedman tests were used to perform comparisons between treatment groups and within group comparisons, respectively.

RESULTS

Oral breathers and nasal breathers showed statistically significant differences in FVC, FEF 25-75%, and TV at T0. They did not present any statistically significant difference in FEV1 and IT% at the same time point.Statistically significant differences were noticed for all indices in the oral breather group after maxillary expansion, while the nasal breather group showed statistically significant differences only in FCV, FEF 25-75%, and TV after treatment.There were no statistically significant differences in all indices 12 months after maxillary expansion between the oral breather and nasal breather groups.

CONCLUSIONS

RME appeared to improve breathing function in both groups. Forced vital capacity (FVC), forced expiratory flow at 25-75% of vital capacity (FEF 25-75), and Tidal volume (TV) reached similar values in both groups after treatment with RME.

Impact of Cervical Spine Rehabilitation on Temporomandibular Joint Functioning in Patients with Idiopathic Neck Pain

Objective

The aim of this study was to assess the effectiveness of a 3-week rehabilitation programme focusing only on the cervical region, pain intensity, range of motion in the cervical spine, head posture, and temporomandibular joint (TMJ) functioning in subjects with idiopathic neck pain who did not report TMJ pain.

Design

A parallel group trial with follow-up.

Methods

The study included 60 participants divided into 2 groups: experimental: n = 25, 27-57 years old, experiencing idiopathic neck pain and who underwent a 3-week rehabilitation programme, and the control, n = 35, 27-47 years, who were cervical pain-free. At baseline and after 3 weeks of treatment in the experimental group and with a 3-week time interval in the control group, pain intensity, head posture in the sagittal plane, range of motion in the cervical spine, and TMJ functioning were evaluated.

Results

After 3 weeks of rehabilitation, there was a significant decrease in pain intensity, improved range of motion of the cervical spine and head posture, and improved clinical condition of TMJ in participants with idiopathic neck pain who did not report TMJ pain.

Conclusion

The study suggested that idiopathic neck pain is associated with limited range of motion in the cervical spine, incorrect head posture, and TMJ dysfunction. Our data suggests that therapy focusing only on the cervical region may improve the clinical condition of the TMJ in subjects with idiopathic neck pain who do not report TMJ pain. These observations could be helpful in physiotherapeutic treatment of neck and craniofacial area dysfunctions. This trial is registered with ISRCTN Registry ISRCTN14511735.

Three-dimensional volumetric evaluation of the different mandibular segments using CBCT in patients affected by juvenile idiopathic arthritis: a cross-sectional study

BACKGROUND

There is currently no information on how different mandibular segments are affected by juvenile idiopathic arthritis. The aim of this paper is to assess volumetric differences of different mandibular segments in subjects with unilateral and bilateral JIA and to compare them with non-JIA control volumes.

MATERIALS AND METHODS

Forty subjects with unilateral TMJ involvement and 48 with bilateral TMJ involvement were selected for the case group and 45 subjects with no known rheumatic comorbidities for the control group. The mandible of each subject was divided according to a validated method into different paired volumes (hemimandible, condyle, ramus and hemibody).

RESULTS

The ANOVA test revealed a statistically significant difference in all the groups for condylar and ramus volumes, and the pairwise comparison evidenced a statistically significant higher condylar and ramus volume in the control group (1444.47 mm³; 5715.44 mm³) than in the affected side in the unilateral JIA group (929.46 mm³; 4776.31 mm³) and the bilateral JIA group (1068.54 mm³; 5715.44 mm³). Moreover, there was also a higher condylar volume in the unaffected side in the unilateral JIA group (1419.39 mm³; 5566.24 mm³) than in the bilateral JIA group and the affected side in the unilateral JIA group.

CONCLUSIONS

The affected side of unilateral JIA patients showed statistically significant lower volumes in the hemimandible, in the condyle and in the ramus. The largest total mandibular volume was observed in the control group, followed by the unilateral JIA group and, lastly, by the bilateral JIA group.

Analysis of Earlier Temporomandibular Joint Disorders in JIA Patients: A Clinical Report

The aim of this study was to analyse the structural characteristics of the temporo-mandibular joint (TMJ) and the dysfunctional consequences induced by disease in subjects with juvenile idiopathic arthritis (JIA). The study was conducted in 25 patients with JIA (median age (IQR), 13.9 (10.9-15.3)) and 26 healthy controls (median age (IQR), 14.3 (11.6-17.2)) years. All enrolled patients were subjected to anamnestic evaluation, laboratory parameters, JIA subclass, and type of therapy for the disease. A clinical-gnathological evaluation, anamnestic and dysfunctional index (Ai and Di), and magnetic resonance imaging of TMJs were performed in all patients. The test group showed a significant reduction (p < 0.001) regarding the clinical findings such as maximal mouth opening, left and rightward laterotrusion and protrusion, and a significant difference in the reported symptoms (TMJ sounds, reduced mouth opening and pain), and Ai and Di (p < 0.001) compared to healthy patients. Correlation analysis showed a significant correlation between the median duration of disease and the maximum mouth opening and between visual analogue scale (VAS) score and maximum mouth opening, leftward laterotrusion, rightward laterotrusion, and protrusion. The results obtained in this study suggest that patients with JIA presented a cohort of symptoms in TMJs in comparison with healthy controls. Moreover, a careful TMJs evaluation and an early diagnosis of TMJs dysfunction and regular follow-ups are recommended in order to prevent and reduce functional and chewing problems in patients with JIA.

Early Treatment with a Slow Maxillary Ni–Ti Leaf Springs Expander

The aim of this brief report is to analyse the available literature on the clinical outcomes of a particular appliance for slow maxillary expansion that consists of one or more nickel–titanium springs. Materials and methods: The main medical databases (Scopus, Web of Sciences, Pubmed and Google Scholar) were scanned up to January 2020 using “slow maxillary expan*”, “slow palatal expan*”, “leaf expander” and “NiTi Palatal Expander” as keywords. Skeletal changes in the maxilla after expansion with the Leaf Expander (L.E.) or similar appliances were taken into consideration while reviewing relevant manuscripts. The review focuses on the comparison between the L.E. and conventional expanders (i.e., Haas and Hyrax) regarding the increase in both the distance between the palatal cusps of the upper first molars and the distance between the palatal cusps of the upper second deciduous molars, as well as the increment of nasal structures and pain connected to expansion procedures. Results: Bibliographic research retrieved 32 articles that were considered eligible for the present study. The limited number of articles currently available in international medical databases is allegedly partly due to the fact that these expanders are currently produced by only one patent holder company, which affects its diffusion. Conclusion: Despite the reduced number of published articles, due to the recent introduction of the L.E. device, most of the authors have found that the effects of the L.E. device are clinically and radiographically comparable to those achievable with the rapid palatal expander.

Posterior Mandibular Displacement-A Systematic Review Based on Animal Studies

Treating extreme mandibular growth is challenging. The mandible is pushed backwards to address itsprotrusion. Nevertheless, conclusions after such displacement in animals have been contradictory. The aim of the present review is to present measurable alterations of the mandible and the condyle following retractionin healthy rats or rabbits. PubMed, Scopus and Web of Science were accessed for relevant studies up to October 2020. Eligibility was determined by the PICOS process, while the risk of bias was estimated with SYRCLE's risk of bias tool. Retraction resulted in a more distal molar occlusion and the condyle rested more posteriorly. Mandibular anteroposterior bilateral growth restriction was achieved, the condylar process measured smaller and its angulation increased. The condylar neck thickened, its posterior surface flattened, the coronoid process was measured longer, and enlarged retromolar density was registered. Differences in the ramus height and the intercondylar distance were insignificant. Changes persisted for the period of study and subsequently the mandible resumed its inherited growth pattern. The timing of mandibular shaping and TMJ outcomes might depend on the properties of the applied force. Stability is of concern and well-structured, long-term studies are expected to resolve the issue and further clarify the results of posterior mandibular displacement.

SPECT/CT Correlation in the Diagnosis of Unilateral Condilar Hyperplasia

Objective: To evaluate the correlation between metabolic bone activity measured by single photon emission computed tomography (SPECT) and the anatomic condylar characteristics acquired by computed tomography (CT), in patients with unilateral condylar hyperplasia (UCH). Method and Materials/Patients: Observational, descriptive study in a group of 71 patients with clinical diagnosis of UCH and indication of SPECT/CT. Bone SPECT images obtained in a gamma-camera GE Infina and processed in a station Xeleris 3 with the program Volumetrix MI Evolution for bone. CT images acquired in a PET/CT Biograph mcT20 equipment (Siemens) processed in a station Osirix V 7.5.1 (Pixmeo, Bomex, Switzerland). Results: The sample included 24 men (33.8%) and 47 women (66.2%). Active state UCH was detected in 40 (56.3%) cases (over 55% uptake in the affected condyle) and 38 (53.5%) presented mandibular deviation to the right side. No significant differences related to sex, age, or mandibular deviation side were found. Mandibular deviation was the only morphologic feature related to active/inactive UCH (p = 0.003). The likelihood of active CH was significantly higher in patients with mandibular deviation higher than 6 mm compared with <6 mm (odds ratio (OR): 3.51, confidence interval (CI) 95%: 1.27–9.72). Conclusion: There is a significant correlation between the magnitude of mandibular deviation quantified on CT and metabolic findings obtained by SPECT in patients with UCH. The risk of active UCH is 3.5 times higher in patients with a mandibular deviation ≥6 mm.

Relationship between Tooth Loss and the Medications Used for the Treatment of Rheumatoid Arthritis in Japanese Patients with Rheumatoid Arthritis: A Cross-Sectional Study

Background: There is limited information regarding the association between tooth loss and the medications used for the treatment of rheumatoid arthritis (RA). Here, we examined the association between tooth loss, disease severity, and drug treatment regimens in RA patients. Method: This study recruited 94 Japanese patients with RA. The severity of RA was assessed using the Steinbrocker classification of class and stage. Data on RA medications were obtained from medical records. We examined the associations between tooth loss, RA severity, and drug treatment regi mens using multinomial logistic regression analyses. Results: Patients with 1–19 teeth had significantly higher odds ratios (ORs) of taking methotrexate (MTX) (OR, 8.74; 95% confidence interval (CI), 1.11–68.8) and biologic disease-modifying antirheumatic drugs (bDMARDs) (OR, 21.0; 95% CI, 1.3–339.1) compared to those with 27–28 teeth when adjusted for RA severity (class). Furthermore, patients with 1–19 teeth had significantly higher ORs of taking MTX (OR, 9.71; 95% CI, 1.22–77.1) and bDMARDs (OR, 50.2; 95% CI, 2.55–990.6) compared to those with 27–28 teeth when adjusted for RA severity (stage). Conclusion: RA patients with fewer teeth were more likely to take stronger RA therapies, independent of RA severity and other factors.

The Modern and Digital Transformation of Oral Health Care: A Mini Review

Dentistry is a part of the field of medicine which is advocated in this digital revolution. The increasing trend in dentistry digitalization has led to the advancement in computer-derived data processing and manufacturing. This progress has been exponentially supported by the Internet of medical things (IoMT), big data and analytical algorithm, internet and communication technologies (ICT) including digital social media, augmented and virtual reality (AR and VR), and artificial intelligence (AI). The interplay between these sophisticated digital aspects has dramatically changed the healthcare and biomedical sectors, especially for dentistry. This myriad of applications of technologies will not only be able to streamline oral health care, facilitate workflow, increase oral health at a fraction of the current conventional cost, relieve dentist and dental auxiliary staff from routine and laborious tasks, but also ignite participatory in personalized oral health care. This narrative article review highlights recent dentistry digitalization encompassing technological advancement, limitations, challenges, and conceptual theoretical modern approaches in oral health prevention and care, particularly in ensuring the quality, efficiency, and strategic dental care in the modern era of dentistry.

Safety and Effects of the Rapid Maxillary Expander on Temporomandibular Joint in Subjects Affected by Juvenile Idiopathic Arthritis: A Retrospective Study

BACKGROUND

In Juvenile Idiopathic Arthritis (JIA) temporo-mandibular joints are often affected causing skeletal and dental malocclusions. The most frequent condition is mandibular hypoplasia, that may be associated with maxillary hypoplasia. The aim of this retrospective case control study is to investigate the effects and the safety of rapid maxillary expansion (RME) in growing patients affected by JIA. It was evaluated whether RME could be performed without complications on TMJs of JIA patients using DC/TMD protocol, and naso-maxillary transversal parameters were compared with the ones obtained on healthy patients.

METHODS

Twenty-five patients affected by JIA that ceased to manifest TMJ (Temporo-Mandibular Joint) symptoms in the previous year were treated with RME to solve the maxillary transverse hypoplasia. Postero-anterior cephalometric tracings were collected before and after treatment; linear measurements were obtained to study maxillary and nasal cavity modifications. Data were compared to those of a similar group of twenty-five healthy patients. Paired t-test and Independent t-test were used to evaluate changes before and after treatment in each group and to perform a comparison between the groups.

RESULTS

All patients demonstrated a statistically significant increase in nasal cavity width, maxillary width and upper and lower intermolar width. No patients presented a worsening of their TMJs condition. Intragroup comparisons revealed significant changes of cephalometric measurements, but no difference was found when comparing JIA and healthy patients.

CONCLUSIONS

Growing patients with JIA that ceased to show signs of active TMJ involvement for at least one year could be safely treated with RME, expecting similar benefits to those of healthy patients. Dentists and rheumatologists should be informed of safety and potential benefits of palatal expansion in JIA patients in order to improve the outcome of orthodontic treatment and reduce the indication for more invasive procedures (i.e., Surgical Assisted Rapid Maxillary Expansion).

A User-Friendly Protocol for Mandibular Segmentation of CBCT Images for Superimposition and Internal Structure Analysis

BACKGROUND

Since cone-beam computed tomography (CBCT) technology has been widely adopted in orthodontics, multiple attempts have been made to devise techniques for mandibular segmentation and 3D superimposition. Unfortunately, as the software utilized in these methods are not specifically designed for orthodontics, complex procedures are often necessary to analyze each case. Thus, this study aimed to establish an orthodontist-friendly protocol for segmenting the mandible from CBCT images that maintains access to the internal anatomic structures.

METHODS

The "sculpting tool" in the Dolphin 3D Imaging software was used for segmentation. The segmented mandible images were saved as STL files for volume matching in the 3D Slicer to validate the repeatability of the current protocol and were exported as DICOM files for internal structure analysis and voxel-based superimposition.

RESULTS

The mandibles of all tested CBCT datasets were successfully segmented. The volume matching analysis showed high consistency between two independent segmentations for each mandible. The intraclass correlation coefficient (ICC) analysis on 20 additional CBCT mandibular segmentations further demonstrated the high consistency of the current protocol. Moreover, all of the anatomical structures for superimposition identified by the American Board of Orthodontics were found in the voxel-based superimposition, demonstrating the ability to conduct precise internal structure analyses with the segmented images.

CONCLUSION

An efficient and precise protocol to segment the mandible while retaining access to the internal structures was developed on the basis of CBCT images.

Buccal Bone Changes Around First Permanent Molars and Second Primary Molars after Maxillary Expansion with a Low Compliance Ni-Ti Leaf Spring Expander

Background: Vestibular bone thickness changes and dento-alveolar buccal tipping of second primary molars and of first molars after maxillary expansion performed with a slow maxillary expansion protocol was investigated. Methods: Twenty patients (mean age 7.3 ± 0.9 years old; 9 male and 11 female) were treated according to the Leaf Expander protocol. Buccal alveolar bone thickness (BT), buccal alveolar bone height (BH), inter-dental angle (TIP), and inter-molar width (IW) regarding first molars and second primary molars were calculated before and after expansion on cone beam computed tomography (CBCT) images. Descriptive statistics and paired t-tests were used to assess changes between the pre-treatment and post-treatment measurements. Results: Bone thickness vestibular to second primary molars and intermolar width of both teeth were the only variables that showed statistically significant changes. Conclusions: It appears that buccal bone thickness vestibular to first molars was not significantly reduced after maxillary expansion with the Leaf Expander. The clinical use of a slow maxillary expander with Ni-Ti springs appears efficient and safe in in the correction of maxillary hypoplasia during mixed dentition.

Relationship between Breastfeeding and Malocclusion: A Systematic Review of the Literature

BACKGROUND

The purpose of this systematic review was to analyze the available literature about the influence of breastfeeding in primary and mixed dentition on different types of malocclusions.

METHODS

Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols (PRISMA-P) guidelines were used to perform the present review. The following electronic databases were searched: Pubmed, Evidence-Based Medicine Reviews (EBMR), Embase, Cochrane Library, Medline, Web of Science and Ovid.

RESULTS

A primary research found a total of 279 articles. Two more papers were also considered from the gray literature. Two hundred sixty-three articles were excluded as they were deemed irrelevant on the basis of: duplicates, title, abstract, methods and/or irrelevant contents. Eighteen papers were selected and included in the qualitative analysis.

CONCLUSIONS

breastfeeding is a positive factor that seems to reduce the incidence of posterior crossbite, skeletal class II and distoclusion in primary and mixed dentition. A sort of positive relationship between months of breastfeeding and risk reduction seems to exist. More longitudinal research is needed to avoid bias in the results, with data collected prospectively on the months of exclusive breastfeeding, by means of specific questionnaires and successive clinical evaluation of the occlusal condition at the primary dentition, mixed dentition and permanent dentition stages.

Correlation between Malocclusion and Allergic Rhinitis in Pediatric Patients: A Systematic Review

BACKGROUND

Oral breathing, nasal obstruction and airway space reduction are usually reported as associated to allergic rhinitis. They have been linked to altered facial patterns and dento-skeletal changes. However, no firm correlation based on the evidence has been established. This systematic review has been undertaken to evaluate the available evidence between malocclusion and allergic rhinitis in pediatric patients.

METHODS

The research refers to Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols (PRISMA-P) guidelines, databases (Medline, Cochrane Library, Pubmed, Embase and Google Scholar) were screened, the quality was evaluated through Quality Assessment of Diagnosfic Accuracy Studies (QUADAS-2).

RESULTS

The articles selected (6 out of initial 1782) were divided on the basis of the study design: two observational randomized study, three case-control study, one descriptive cross-sectional study, and one longitudinal study. A total of 2188 patients were considered. Different results were reported as related to allergic rhinitis ranging from a higher incidence of dental malocclusion, to an increase of palatal depth, and in posterior cross-bite about anterior open-bite and to longer faces and shorter maxillas.

CONCLUSIONS

Most of the studies selected found a rise in the prevalence of both malocclusion and allergic rhinitis in children. However, the level of bias is high, impaired by a poor design and no conclusive evidence can be drawn.

3D Printing of Clear Orthodontic Aligners: Where We Are and Where We Are Going

Clear orthodontic aligners were developed at the end of the 1990s [...].

Increased Risk of Temporomandibular Joint Disorder in Patients with Rheumatoid Arthritis: A Longitudinal Follow-Up Study

We evaluated the incidence of temporomandibular disorder (TMD) in patients with rheumatoid arthritis (RA) and examined the association between TMD and RA, through longitudinal follow-up. Population data from the Korean National Health Insurance Service-Health Screening Cohort from 2002 to 2015 was used. From 514,866 subjects, 3122 with RA were matched with 12,488 controls in a 1:4 ratio. The crude and adjusted models (for obesity, smoking, alcohol consumption, blood pressure, blood glucose, total cholesterol, and Charlson Comorbidity Index scores) were calculated. Chi-square tests, Kaplan-Meier (KM) analysis, and two-tailed analyses were used for statistical analysis. Stratified Cox proportional hazard models were used to assess the hazard ratios (HR) and 95% confidence intervals (CI) for TMD in the RA group, compared to those in the control group. The adjusted HR for TMD in RA was 2.52 (95% CI = 1.70–3.74), compared to the control group. The results were consistent with the subgroup analyses, according to age and sex, except in men older than 60 years of age. KM analysis showed similar results. Hence, we found that patients with RA have a higher risk of TMD, and should be observed for symptoms of the initial stage of TMD to prevent the risk of aggravation.

Impacts of Thresholds of Gray Value for Cone-Beam Computed Tomography 3D Reconstruction on the Accuracy of Image Matching with Optical Scan

In cone-beam computed tomography (CBCT), the minimum threshold of the gray value of segmentation is set to convert the CBCT images to the 3D mesh reconstruction model. This study aimed to assess the accuracy of image registration of optical scans to 3D CBCT reconstructions created by different thresholds of grey values of segmentation in partial edentulous jaw conditions. CBCT of a dentate jaw was reconstructed to 3D mesh models using three different thresholds of gray value (-500, 500, and 1500), and three partially edentulous models with different numbers of remaining teeth (4, 8, and 12) were made from each 3D reconstruction model. To merge CBCT and optical scan data, optical scan images were registered to respective 3D reconstruction CBCT images using a point-based best-fit algorithm. The accuracy of image registration was assessed by measuring the positional deviation between the matched 3D images. The Kruskal-Wallis test and a post hoc Mann-Whitney U test with Bonferroni correction were used to compare the results between groups (α = 0.05). The correlations between the experimental factors were calculated using the two-way analysis of variance test. The positional deviations were lowest with the threshold of 500, followed by the threshold of 1500, and then -500. A significant interaction was found between the threshold of gray values and the number of remaining teeth on the registration accuracy. The most significant deviation was observed in the arch model with four teeth reconstructed with a gray-value threshold of -500. The threshold for the gray value of CBCT segmentation affects the accuracy of image registration of optical scans to the 3D reconstruction model of CBCT. The appropriate gray value that can visualize the anatomical structure should be set, especially when few teeth remain in the dental arch.

Assessment of Parents' Oral Health Literacy and Its Association with Caries Experience of Their Preschool Children

(1) Purpose: To assess the oral health literacy (OHL) of parents and its association with the caries experience of their preschool children attending the Hospital University Sains Malaysia (HUSM), Kota Bharu, Kelantan, Malaysia. (2) Materials and Methods: This is a descriptive cross-sectional study involving a systematic random sampling method, using a sample of 230 parent/preschool child dyads. Among 230 parents, 24 were males and 206 were females (mean age 31.43 ± 5.82); among 230 children, 92 were boys and 138 were girls (mean age 4.82 ± 1.04) attending the pedodontics clinic, HUSM, who participated and met the inclusion criteria. A structured, self-administered oral health literacy questionnaire including sociodemographic factors was used in this study. A child's oral examination was performed to check the dmft (decayed, missing, filled teeth) status. Statistical analysis was done using descriptive and Spearman's correlation analysis and multivariate regression analysis. (3) Results: The mean dmft score of children in relation to the OHL level of parents showed a significant difference (p < 0.00). The mean dmft score of children in relation to the OHL level of parents showed the following relationships: Inadequate (7.49 ± 4.10) followed by marginal (3.28 ± 2.67) and then adequate (0.55 ± 1.55). The incidence of caries amongst children in relation to parental employment was more associated with unemployed parents (6.11 ± 4.43) than with employed parents (2.79 ± 3.65). The caries experience amongst children in relation to education of their parents revealed a significant difference (p < 0.001), and the mean dmft score was high amongst preschool children with primary school qualified parents (10.7 ± 4.10) followed by high school (7.04 ± 3.68), vocational (5.81 ± 3.57), diploma (2.61 ± 2.81), and university (1.29 ± 2.27), respectively. The results revealed a valid significant difference (negative correlation, rs = -0.753 **) between the OHL of parents with the dmft score of their preschool children. The age and gender of parents was not significantly associated with OHL, whereas ethnicity (positive correlation, rs = 0.283 **), education (positive correlation, rs = 0.865 **), and employment (negative correlation, rs = -0.490 **) were found to be significant. Conclusion: We conclude that there is a significant association between the OHL of parents with the dmft score of their preschool children. The logistic regression showed that after adjustment for sociodemographic factors, parents' gender (OR = 0.067, 95% CI: 0.012-0.360), parents' employment status (OR = 3.247, 95% CI: 0.897-11.754), parents' OHL score (OR = 0.042, 95% CI: 0.016-0.114), and child age (OR = 2.195, 95% CI: 1.249-3.857) were significantly associated with dental caries in children. Our study concluded that parents' employment status, age, gender, OHL, and child's age were significantly associated with the caries experience of their preschool children.

Assessing mandibular body changes in growing subjects: a comparison of CBCT and reconstructed lateral cephalogram measurements

The aim of this study is to compare cone-beam computed tomography (CBCT) and bi-dimensional reconstructed lateral cephalograms (RLCs) in assessing mandibular body length and growth and to evaluate how mandibular reshaping influences the error in measuring mandibular body growth in bi-dimensional radiographs. Twenty-five patients with two CBCT scans taken at a mean distance of 2.21 ± 0.5 years were selected. The following measurements were performed: right and left mandibular body length at each point in time, mandibular growth, inter-gonial distance and mandibular symphyseal angle. From each CBCT, an RLC was obtained, and mandibular body length and growth were measured. Data analysis revealed a statistically and clinically significant difference in CBCT and RLC regarding the mandibular length of each patient at each point in time. However, mandibular growth was almost identical. A linear regression was performed to predict growth distortion between RLCs and CBCT depending on the ratio between transverse and sagittal mandibular growth. The expected maximum and minimum distortion, however, appeared not to be significant. In fact, a second linear regression model and a Bland–Altman test revealed a strong correlation between measurements of average mandibular body growth by CBCT and RLCs. As the same distortion occurs in the first and second RLCs, bi-dimensional radiographs remain the method of choice in evaluating mandibular body growth.

Efficacy of Operculectomy in the Treatment of 145 Cases with Unerupted Second Molars: A Retrospective Case-Control Study

The aim of this study is to assess whether operculectomy in patients with retained second molars eases spontaneous tooth eruption in respect to untreated controls. Two hundred and twenty-two patients with delayed eruption of at least one second molar were selected from the archives of the Department of Orthodontics, Milan, Italy. Eighty-eight patients, 40 males and 48 females (mean age 14.8 ± 1.3 years), met the inclusion criteria. Records were then divided into case and control groups. The case group consisted of patients that underwent removal of the overlaying mucosa over second molars (i.e., operculectomy) and the control group consisted of subjects who retained their operculum over an unerupted second molar and were followed for one year without performing any treatment. A total of 145 impacted second molars were considered (75 cases, 70 controls). A risk ratio with 95% confidence interval was used to compare the prevalence of eruption in the two groups. Spontaneous eruption occurred in 93.3% of cases in the operculectomy group (70/75), while in the control group, 10% teeth erupted spontaneously (7/70). Spontaneous eruption in the upper arch occurred in 95.2% of cases among treated patients (40 out of 42), while in the lower arch, spontaneous eruption occurred in 90.9% of cases (30 out of 33). Spontaneous eruption of the upper second molars in the control group occurred in 8.5% of cases (3 out of 35), while in the lower arch, it occurred in 8.5% (3 out of 35). Operculectomy can ease the spontaneous eruption of retained second molars and reduce the chances of inclusion.

Volumetric Changes in the Upper Airways after Rapid and Slow Maxillary Expansion in Growing Patients: A Case-Control Study

The aim is to evaluate changes in the volume of the upper airways before and after slow maxillary expansion (SME) obtained with the flexible properties of a nickel titanium leaf spring and rapid maxillary expansion (RME) with a conventional Hyrax appliance in growing patients. The records of 1200 orthodontic patients undergoing maxillary expansion from 2018 to 2019 were analyzed; among these pre and post treatment CBCT scans of 22 patients (mean age 8.2 ± 0.6 years old) treated by SME were compared with those obtained from 22 patients (mean age 8.1 ± 0.7 years old) treated by RME banded on the second primary molars. The following inclusion criteria were used: Maxillary transverse constriction, good general health, and no previous orthodontic treatment. Volumes of nasal cavity (NCavV), nasopharynx (NsPxV), and right and left maxillary sinuses (MSV) were calculated with ITK-SNAP. Shapiro–Wilk test revealed a normal distribution of data in each group. Paired t-test was used for within-group comparisons and independent t-test for between-group comparisons. Statistically significant increases occurred in NCavV, NsPxV, and MSVs after treatment with both appliances. No statistically significant difference between the appliances occurred in NCavV, NsPxV, and MSVs. Method error was considered negligible (mean intra-operator and inter-operator intraclass correlation coefficient were 0.928 and 0.911, respectively). It appears that both appliances produce similar effects on the different segments of the upper airway tract.

Effects on the Facial Growth of Rapid Palatal Expansion in Growing Patients Affected by Juvenile Idiopathic Arthritis with Monolateral Involvement of the Temporomandibular Joints: A Case-Control Study on Posteroanterior and Lateral Cephalograms

BACKGROUND

Juvenile idiopathic arthritis (JIA) affecting temporomandibular joints (TMJ) in growing patients results in maxillofacial deformities, especially if only one condyle has been affected by the rheumatic disease. Mandibular hypoplasia is the most common issue and it may be associated with maxillary hypoplasia. The aim of this retrospective case-control study is to evaluate the effects of rapid maxillary expansion (RME) in these patients.

METHODS

25 growing patients affected by maxillary hypoplasia, currently in a quiescent phase of JIA for at least one year and monolateral involvement of the TMJs, were treated with RME. Data gathered from posteroanterior and lateral cephalograms before and after 1 year from RME were compared to those of 25 non-JIA controls.

RESULTS

Nasal cavity width, maxillary width and upper and lower intermolar width statistically increased. Maxillary and mandibular symmetry indexes presented a statistically significant increase, so did the skeletal class. No signs or symptoms of TMJ activity of JIA occurred according to Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) criteria. No difference was found when comparing JIA and non-JIA patients apart from the better improvement of several mandibular symmetry indexes in the affected TMJ side of JIA patients. This event is allegedly due to a worse baseline asymmetry in JIA patients that underwent a bigger relative improvement after treatment.

CONCLUSIONS

Results suggest that solving maxillary hypoplasia and, therefore, premature contacts are likely to have allowed mandibular repositioning and condylar growth. RME is a safe and effective solution that can substantially improve maxillary and mandibular symmetry in growing patients affected by JIA with TMJ involvement.

Three-Dimensional Evaluation of Maxillary Sinus Changes in Growing Subjects: A Retrospective Cross-Sectional Study

This study aims to evaluate changes of maxillary sinuses in growing subjects. Cone Beam Computed Tomography (CBCT) scans of 146 patients were divided according to gender and age (6–8, 9–11, 12–14 years old). Left, right and total maxillary sinus volume (MSV-R, MSV-L, MSV-Tot) and surface (MSS-R, MSS-L, MSS-Tot), left and right linear maximum width (LMW-L, LMW-R), depth (LMD-R, LMD-L) and height (LMH-R, LMH-R) were calculated using Mimics Research 22. Kruskal–Wallis Test and showed a statistically significant increase in both genders for all variables. Pairwise comparisons in females are always statistically significant in: LMH-R, LMH-R, MSS-Tot, MSV-Tot. All other variables showed a statistical significant increase between 9–11 and 12–14, and between 6–8 and 12–14 age groups, apart from LMSW-R, LMSW-L, LMSD-R, LMSD-L between 6–8 and 12–14 age groups. Pairwise comparisons in males are always and only statistically significant between 9–11 and 12–14, and between 6–8 and 12–14 groups. Symmetrical measurements (right and left) evaluated using Wilcoxon test retrieved no statistical significant difference. Comparisons between measurements on male and female subjects using Mann–Whitney test showed a statistical significant difference in 6–8 years group in MSV-R, MSV-L and MSV-Tot, and in 12–14 age group in MSV-R, MSV-L, MSV-Tot, MSS-r, MSS-l, MSS-Tot, MSW-R, MSW-L, MSD-R, MSD-L. Intraclass Correlation Coefficient (ICC) assessing inter-operator and intra-operator concordance retrieved excellent results for all variables. It appears that maxillary sinus growth resembles the differential peak of growth in male and female subjects. Sinuses starts to develop early in female subjects. However, in the first and last age group female sinuses are statistically significantly smaller compared to male ones. In male subjects, sinus growth occurs mainly between the second and third age group whilst in female subjects it starts between the first and second age group and continues between the second and the last. Sinus has a vertical development during the peak of growth, which is the main reason for its increase in volume.