A Simple Technique Using a Modified Nance Appliance as Anchorage for Maxillary Molar Distalization—Two Case Reports

Maxillary molar distalization to correct a dental Class II molar relationship and to create space to relieve crowding has been a long-lasting subject of debate in orthodontics. Generally, to distalize maxillary molars, an intra-arch distalization appliance is favored over an inter-arch appliance since it does not utilize mandibular dentition as an anchorage, so some unwanted side effects on mandibular incisors can be avoided. A variety of intra-arch appliances have been developed to distalize maxillary molars, such as the pendulum, Jones jig, first class appliance, distal jet, and modified C-palatal plate. Although they could achieve efficient molar distalization, the learning curve of proper appliance insertion and activation is relatively long. In addition, the appliances are not comfortable for the patients due to the bulky activation units, especially when the activation units are designed in the palatal area. The current manuscript describes a novel and effective maxillary intra-arch molar distalization appliance—a modified Nance appliance technique, which consists of: (1) palatally, a big acrylic button against the palatal rugae and connected to the premolars with wide mesh pads; (2) buccally, regular brackets on maxillary premolars and first molars with sectional round stainless steel archwires and open coil springs between the second premolar and first molar. Either bilateral or unilateral maxillary molar distalization can be achieved with this appliance, and the Class II elastics are not needed. It is simple to be fabricated, delivered, and activated, and it is comfortable for patients. © 2022 by the authors. Licensee MDPI, Basel, Switzerland

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. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Transverse Growth of the Maxillo-Mandibular Complex in Untreated Children: A Longitudinal Cone Beam Computed Tomography Study

The aim of this study is to evaluate the longitudinal transverse growth of the maxillo-mandibular complex in untreated children using the Cone Beam Computed Tomography (CBCT)Two sets of scans on 12 males (mean 8.75 years at T1 and 11.52 years at T2) and 18 females (mean 9.09 years at T1 and 10.80 years at T2) were analyzed using Dolphin 3D imaging. The transverse widths of various maxillary and mandibular skeletal landmarks and the dentoalveolar and dental landmarks at the level of first molars were measured. Overall, there were greater increases in the transverse dimension in the posterior than anterior portions of the maxilla and mandible. The increase in intergonial width of the mandible seems to be primarily due to the lengthening of the mandibular body. The dentoalveolar process at the first molar level increases at an equal rate corono-apically and is independent to the changes in molar inclination. When comparing maxillary dentoalveolar changes with that of the mandible, greater increases were noticed in the maxilla, which might be explained by the presence of sutural growth in the maxilla. Moreover, the first molars maintain their coordination with each other despite the differential increase in the maxillary and mandibular dentoalveolar processes. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Sagittal and Vertical Growth of the Maxillo–Mandibular Complex in Untreated Children: A Longitudinal Study on Lateral Cephalograms Derived from Cone Beam Computed Tomography

The aim of this longitudinal study was to evaluate the sagittal and vertical growth of the maxillo–mandibular complex in untreated children using orthogonal lateral cephalograms com-pressed from cone beam computed tomography (CBCT). Two sets of scans, on 12 males (mean 8.75 years at T1, and 11.52 years at T2) and 18 females (mean 9.09 years at T1, and 10.80 years at T2), were analyzed using Dolphin 3D imaging. The displacements of the landmarks and rotations of both jaws relative to the cranial base were measured using the cranial base, and the maxillary and mandibular core lines. From T1 to T2, relative to the cranial base, the nasion, orbitale, A-point, and B-point moved anteriorly and inferiorly. The porion moved posteriorly and inferiorly. The ANB and mandibular plane angle decreased. All but one subject had forward rotation in reference to the cranial base. The maxillary and mandibular superimpositions showed no sagittal change on the A-point and B-point. The U6 and U1 erupted at 0.94 and 1.01 mm/year (males) and 0.82 and 0.95 mm/year (females), respectively. The L6 and L1 erupted at 0.66 and 0.88 mm/year (males), and at 0.41 mm/year for both the L6 and the L1 (females), respectively. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

RANKL Deletion in Periodontal Ligament and Bone Lining Cells Blocks Orthodontic Tooth Movement

The bone remodeling process in response to orthodontic forces requires the activity of osteoclasts to allow teeth to move in the direction of the force applied. Receptor activator of nuclear factor-κB ligand (RANKL) is essential for this process although its cellular source in response to orthodontic forces has not been determined. Orthodontic tooth movement is considered to be an aseptic inflammatory process that is stimulated by leukocytes inclduing T and B lymphocytes which are presumed to stimulate bone resorption. We determined whether periodontal ligament and bone lining cells were an essential source of RANKL by tamoxifen induced deletion of RANKL in which Cre recombinase was driven by a 3.2 kb reporter element of the Col1α1 gene in experimental mice (Col1α1.CreERTM+.RANKLf/f) and compared results with littermate controls (Col1α1.CreERTM-.RANKLf/f). By examination of Col1α1.CreERTM+.ROSA26 reporter mice we showed tissue specificity of tamoxifen induced Cre recombinase predominantly in the periodontal ligament and bone lining cells. Surprisingly we found that most of the orthodontic tooth movement and formation of osteoclasts was blocked in the experimental mice, which also had a reduced periodontal ligament space. Thus, we demonstrate for the first time that RANKL produced by periodontal ligament and bone lining cells provide the major driving force for tooth movement and osteoclastogenesis in response to orthodontic forces

Rdzeniowy zespół twarzowo-palcowy: częsty zespół w nietypowej lokalizacji

Background and purpose Cheiro-oral syndrome (COS) is an established neurological entity characterized by a sensory impairment confined to the mouth angle and ipsilateral finger(s)/ hand. The current understanding of localization is a concomitant involvement of the spinothalamic and trigeminothalamic tract between the cortex and pons. The cervical spinal cord has not been mentioned in this situation yet, and this unusual location may heretofore increase the risk of misdiagnosis. Material and methods Six patients who presented with unilateral COS due to cervical cord disorder are reported. Results All patients were women and their age ranged between 42 and 70 years. Their neurological deficits included unilateral paraesthesiae restricted to cheiro-oral distribution, positive radicular sign, and mild change of tendon reflex. Cervical spinal stenosis at middle/lower cervical spine with variable magnitude of cord compression and intrinsic cord damage was found. A diagnostic dilemma obviously arises from the lack of tangible neurological signs or typical pattern of myelopathy, in addition to the previous concept of cerebral involvement. A benign course ensued in all reported patients. Conclusions Cheiro-oral syndrome can be an early neurological sign for cervical cord disorder; it further suggests that it is a strong neurological but weak localizing sign. A reciprocal influence of multiple factors is considered to generate COS at the cervical cord. Therefore, an absence of brain pathology should lead to a thorough examination of the cervical cord in case of COS.Wstęp i cel pracy Zespół twarzowo-palcowy (ZTP) jest znanym zespołem neurologicznym, który cechuje się niedoczulicą ograniczoną do kącika ust i palców ręki lub ręki po tej samej stronie. Bieżący stan wiedzy dotyczący lokalizacji uszkodzenia w tym zespole wskazuje na jednoczesne zajęcie dróg rdzeniowo-wzgórzowej i trójdzielno-wzgórzowej pomiędzy mostem i korą mózgową. W tym kontekście nie wymieniano dotąd uszkodzenia rdzenia kręgowego w odcinku szyjnym, a taka nietypowa lokalizacja uszkodzenia może zwiększyć ryzyko błędnego rozpoznania miejsca uszkodzenia. Materiał i metody W pracy przedstawiono dane dotyczące 6 pacjentek z jednostronnym ZTP spowodowanym występowaniem nieprawidłowości w obrębie rdzenia kręgowego. Wyniki Zakres wieku pacjentek wynosił od 42 do 70 lat. Objawy neurologiczne obejmowały jednostronne parestezje ograniczone do obszaru twarzy i ręki, objaw korzeniowy i niewielkie nieprawidłowości w zakresie odruchów głębokich. Stwierdzono występowanie zwężenia kanału kręgowego w środkowej lub dolnej części odcinka szyjnego z uciskiem rdzenia kręgowego i uszkodzeniem wewnątrz rdzenia kręgowego. Wątpliwości diagnostyczne wynikały z braku typowych objawów neurologicznych mielopatii i stwierdzenia lokalizacji zmian nieodpowiadającej wcześniejszym opiniom na temat mózgowego pochodzenia zespołu. U wszystkich opisywanych pacjentek przebieg schorzenia był łagodny. Wnioski Zespół twarzowo-palcowy może być wczesnym objawem neurologicznym nieprawidłowości w obrębie rdzenia kręgowego. Stanowi istotny objaw neurologiczny, ale jego wartość lokalizacyjna jest niewielka. Powstawanie ZTP wskutek uszkodzenia rdzenia kręgowego wynika z wzajemnych oddziaływań wielu czynników. W razie braku uchwytnej patologii mózgu należy w przypadkach ZTP przeprowadzić szczegółowe badania rdzenia kręgowego w odcinku szyjnym

Genes and Pathways Associated with Skeletal Sagittal Malocclusions: A Systematic Review

Skeletal class II and III malocclusions are craniofacial disorders that negatively impact people’s quality of life worldwide. Unfortunately, the growth patterns of skeletal malocclusions and their clinical correction prognoses are difficult to predict largely due to lack of knowledge of their precise etiology. Inspired by the strong inheritance pattern of a specific type of skeletal malocclusion, previous genome-wide association studies (GWAS) were reanalyzed, resulting in the identification of 19 skeletal class II malocclusion-associated and 53 skeletal class III malocclusion-associated genes. Functional enrichment of these genes created a signal pathway atlas in which most of the genes were associated with bone and cartilage growth and development, as expected, while some were characterized by functions related to skeletal muscle maturation and construction. Interestingly, several genes and enriched pathways are involved in both skeletal class II and III malocclusions, indicating the key regulatory effects of these genes and pathways in craniofacial development. There is no doubt that further investigation is necessary to validate these recognized genes’ and pathways’ specific function(s) related to maxillary and mandibular development. In summary, this systematic review provides initial insight on developing novel gene-based treatment strategies for skeletal malocclusions and paves the path for precision medicine where dental care providers can make an accurate prediction of the craniofacial growth of an individual patient based on his/her genetic profile. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Total Maxillary Arch Distalization by Using Headgear in an Adult Patient: Reconsidering the Traditional Strategy in Modern Orthodontics

Although headgear is rarely used in adult patients, its use in adults is mainly for anchorage control. In the current case report, a 24-year-old patient had a skeletal Class I relationship with a Class II tendency, brachyfacial pattern, significant facial asymmetry, and dental 3/4 cusp Class II molar and canine relationships on both sides. The patient declined surgery, and facial asymmetry was not his concern. The final treatment goal was to achieve a stable Class I dental relationship and normal occlusion without significantly compromising the patient\u27s profile. The patient was compliant with the use of cervical-pull headgear after he refused the options of orthodontic-orthognathic combined treatment, maxillary premolar extraction, or temporary skeletal anchorage mini-implants. A 5-mm maxillary arch distal movement was accomplished without significant distal tipping of the molar crowns. The active treatment duration was 31 months. Proper overbite and overjet, balanced occlusion, and an acceptable facial profile were achieved. The treatment results inspire reconsideration of the possibility of using headgear in dental Class II correction in adult patients. (Angle Orthod. 2021;91:267-278). © 2021 Allen Press Inc.. All rights reserved

The Reliability of Two- and Three-Dimensional Cephalometric Measurements: A CBCT Study

Cephalometry is a standard diagnostic tool in orthodontic and orthognathic surgery fields. However, built-in magnification from the cephalometric machine produces double images from left-and right-side craniofacial structures on the film, which poses difficulty for accurate cephalometric tracing and measurements. The cone-beam computed tomography (CBCT) images not only allow three-dimensional (3D) analysis, but also enable the extraction of two-dimensional (2D) images without magnification. To evaluate the most reliable cephalometric analysis method, we extracted 2D lateral cephalometric images with and without magnification from twenty full-cranium CBCT datasets; images were extracted with magnification to mimic traditional lateral cephalograms. Cephalometric tracings were performed on the two types of extracted 2D lateral cephalograms and on the reconstructed 3D full cranium images by two examiners. The intra-and inter-examiner intraclass correlation coefficients (ICC) were compared between linear and angular parameters, as well as between CBCT datasets of adults and children. Our results showed that overall, tracing on 2D cephalometric images without magnification increased intra-and inter-examiner reliability, while 3D tracing reduced inter-examiner reliability. Angular parameters and children’s images had the lowest inter-and intra-examiner ICCs compared with adult samples and linear parameters. In summary, using lateral cephalograms extracted from CBCT without magnification for tracing/analysis increased reliability. Special attention is needed when analyzing young patients’ images and measuring angular parameters. © 2021 by the authors. Licensee MDPI, Basel, Switzerland