Mandibular Dentition Research Articles

Automated dentition segmentation: 3D UNet-based approach with MIScnn framework

Advancements in technology have led to the adoption of digital workflows in dentistry, which require the segmentation of regions of interest from cone-beam computed tomography (CBCT) scans. These segmentations assist in diagnosis, treatment planning, and research. However, manual segmentation is an expensive and labor-intensive process. Therefore, automated methods, such as convolutional neural networks (CNNs), provide a more efficient way to generate segmentations from CBCT scans. A three-dimensional UNet-based CNN model, utilizing the Medical Image Segmentation CNN framework, was used for training and generating predictions from CBCT scans. A dataset of 351 CBCT scans, with ground-truth labels created through manual segmentation using AI-assisted segmentation software, was prepared. Data preprocessing, augmentation, and model training were performed, and the performance of the proposed CNN model was analyzed. The CNN model achieved high accuracy in segmenting maxillary and mandibular teeth from CBCT scans, with average Dice Similarity Coefficient values of 91.83% and 91.35% for maxillary and mandibular teeth, respectively. Performance metrics, including Intersection over Union, precision, and recall, further confirmed the model's effectiveness. The study demonstrates the efficacy of the three-dimensional UNet-based CNN model within the Medical Image Segmentation CNN framework for automated segmentation of maxillary and mandibular dentition from CBCT scans. Automated segmentation using CNNs has the potential to deliver accurate and efficient results, offering a significant advantage over traditional segmentation methods.

Effect of loading angle and fabrication materials on stress distribution with periodontal splint in compromised periodontal tissues: a finite element study

Objective: To evaluate the effect of polyetheretherketone (PEEK) periodontal splints and splints made from other materials under static loading on stress distributions in periodontal tissues, cement layer, and splints themselves. Methods: A finite element model based on cone-beam CT imaging data of a 25-year-old male patient (treated at the Department of Prosthodontics, School of Stomatology, The Fourth Military Medical University in October 2021 for a cracked maxillary molar) with a healthy and intact mandibular dentition and periodontal health was constructed. The finite element model included anterior mandible dentition, mandibular bone model without bone resorption (WBR group), a periodontally compromised mandible model (control group), and three types of periodontal splints: a PEEK periodontal splint (0.7 mm thick, Young's modulus: 4.1 MPa), a fiber-reinforced resin (FRC) splint (1.0 mm thick, Young's modulus: 37.0 MPa), and a titanium splint (1.2 mm thick, Young's modulus: 110.0 MPa). The bone resorption models fixed with different periodontal splints constituted the experimental groups (PEEK group, FRC group and titanium group). Loading of 100 N was applied on the midpoint of the incisal edge of tooth 41. The direction was set at 0°, which was parallel to the long axis of the tooth and downward. The buccal to lingual and downward angles were 30°and 60°, respectively, perpendicular to the long axis of the tooth and 90° to the lingual side. The finite element analysis software was utilized to analyze the stress distribution characteristics of the periodontal tissues, adhesive layer, and the splint itself in the anterior mandibular teeth among the different group. Results: Under the different loading simulation, in the control group, the maximal von Mises stresses of periodontal ligament and bone were 15.7-50.2 MPa and 38.8-130.3 MPa, respectively, and in the WBR group, the maximal von Mises stresses of periodontal ligament and bone were 3.6-6.4 MPa and 16.5-42.7 MPa, respectively. Under the same loading conditions, the magnitude of maximal von Mises stresses in periodontal tissues in the PEEK group was 4.6-6.2 MPa, and the magnitude of stresses in the periodontal ligament of 41 teeth in the WBR group was similar to that in the PEEK group, but higher than that in the FRC and titanium groups. The maximal von Mises stresses of each group is primarily distributed in the periodontal ligament and alveolar bone at the cervical area of the tooth. The higher the elastic modulus of the splint, the higher its own maximal von Mises stresses, and the smaller the maximal principal stresses transmitted to the adhesive layer. In the PEEK group and titanium group, the stress distribution area in the adhesive layer and the splint was near the splint connection adjacent to tooth 41. Conclusions: Periodontal splints fabricated from three types of materials, are effective in distributing stress within the periodontal tissues of the abutment teeth. Compared to FRC and titanium group, the higher PEEK splint stress value was obtained, and the smaller the stress value was transmitted to its adhesive layer.

Accuracy of imaging software usable in clinical settings for 3D rendering of tooth structures.

The aim of the present study was to evaluate the segmentation accuracy of the dentition by testing four open-source semi-automatic software programs. Twenty CBCT scans were selected to perform semi-automatic segmentation of the maxillary and mandibular dentition. The software programs tested were InVesalius, ITK-SNAP, 3D Slicer, and Seg3D. In addition, each tooth model was manually segmented using Mimics software; this was set as the gold standard (GS) reference of the investigation. A specific 3D imaging technology was used to perform the superimposition between the tooth models obtained with the semi-automatic software and the GS model as well as 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 with the manual segmentation (GS). Qualitative assessments were performed using color-coded maps. All data were statistically analyzed to perform comparisons between the investigated software programs. Statistically significant differences were found in the volumetric and matching percentage data (P 0.05). InVesalius was the most accurate software program for 3D rendering of the dentition, with a volumetric bias (Mimics software) ranging from 4.59 to 85.79 mm3, while ITK-SNAP showed the highest volumetric bias, ranging from 30.22 to 319.83 mm3. The mismatched area was mainly located at the radicular tooth region. The volumetric data showed excellent inter-software reliability, with coefficient values ranging from 0.951 to 0.997. Different semi-automatic software algorithms could generate different patterns of inaccuracy error in the segmentation of teeth.

Development and eruption of human teeth in the Chinese population: a comprehensive dental atlas

AimThe first comprehensive chart on dental development was published 75 years ago based on Caucasian children and this has been used as a standard dental chart to date. Few population specific charts have been developed recently and updated dental charts on modern subjects can provide more information on dental development patterns. This study aims to construct a comprehensive dental atlas for modern Chinese children and young adults to assist in clinical, forensic, and public health applications.MethodsThe study sample comprised of 2,306 subjects, age ranging from 2 to 24 years belonging to Chinese ethnicity. Dental formation and eruption of permanent teeth and resorption of primary teeth were analyzed separately for females and males. For each age range, the number of teeth (n), and the stage of development was calculated for first (Q1), second (Q2) and third quartiles (Q3). Similar analysis was performed for the position of permanent teeth and the resorption of primary teeth. To determine the variations between the sex, Mann-Whitney U-test was conducted by comparing the median (Q2) stages.ResultsVariations in dental formation and eruption of permanent teeth and resorption of primary teeth were observed between maxillary and mandibular dentitions and between the sex, however the difference was not statistically significant (p = 0.535 to p = 1.000). The dental atlas was presented separately for Chinese females and males.ConclusionThis atlas on modern Chinese population serves as a practical tool to assist in clinical diagnosis and treatment planning, in forensic investigations as well as indicators of developments in public health.

More molar distal movement than pretreatment cone-beam computed tomography posterior space available at the root level in mandibular dentition distalization with microimplants.

To compare the mandibular posterior space available before treatment and the distance of molar distalization achieved after mandibular dentition distalization with microimplants. A total of 66 Class I or III adult patients (mean age = 24.46 ± 4.89 years) who underwent molar distalization using microimplants were retrospectively included. The posterior space available distal to the second molar before treatment and the distance of distalization achieved after treatment were measured using axial cone-beam computed tomography images (0, 2, 4, and 6 mm apical to the second molar root furcation). Changes in lingual cortical thickness and molar root length after treatment were examined. Paired t-test or Wilcoxon signed-rank test was performed to compare measurements before and after treatment. Spearman correlation analysis was performed to assess the relationship between thinning of the cortical plate and root resorption. Achieved distalization distance was significantly greater than pretreatment posterior space available by 0.8 mm at all root levels (P < .001). The difference was greater toward the root apex level and greater in the Class III group than the Class I group. Lingual cortical thickness was significantly decreased after treatment along with resorption of the second molar distal root (P < .001). In addition, a positive correlation was found between thinning of the cortical plate and distal root resorption of the molar (P < .001). Achieved distalization distance of the mandibular molar using microimplants was greater than the pretreatment posterior space available. Thinning of the lingual cortex and root resorption were observed after distalization.

Comparative histologic evaluation of teeth decalcified by conventional method versus microwave induced decalcification

Abstract Introduction: Complete demineralization of hard tissues with preservation of organic components to retain their tissue architecture and to obtain thin section for histological examination is done by a process known as “decalcification”. Tooth decalcification may be achieved by subjecting the tissue to a decalcifying chemical agent and employing heat, vacuum, or electric current to enhance the procedure. Completion of decalcification is adjudged by determination of end-point. Histological examination of hard tooth tissues and pulp is essential for diagnosis of developmental pathologies, pulp pathologies, and forensic odontology analysis as well as for research purpose. Aim: In our study, we studied the time consumed for decalcification procedure by conventional decalcification method and with the microwave-assisted decalcification method for teeth, using 5% nitric acid, 5% trichloracetic acid, and 14% EDTA (Ethylenediaminetetraacetic acid), respectively, along with morphological preservation of dentin and pulp tissue by analyzing preservation of their issue structure (pulp shrinkage, odontoblastic layer damage) and staining efficacy (patchy staining) for the three types of decalcifying agents used. Materials and Method: The sample for this study included 120 freshly extracted teeth consisting of teeth of mandibular dentition. Samples were divided into two study groups: Group I: Decalcified by Conventional method Group II: Decalcified by Microwave method. Each group consisted of, three sub-groups employing a different decalcifying agent from among the three decalcifying agents used, that is, 5% nitric acids, 5% trichloroacetic acid, and 14%EDTA respectively. Result: The difference in speed of decalcification for both groups showed significant result. In either group, decalcification was fastest using 5% nitric acid. The difference in number of decalcified teeth sections showing shrinkage of pulp was not statistically significant for both groups. Damaged odontoblastic layer was evident only in the teeth treated with 5% nitric acid by microwave method. Patchy staining was observed in a few samples of all sample groups except those decalcified with EDTA by conventional method but the results were not statistically different on intercomparison. Discussion and Conclusion: Our results are similar to those of previous studies and we found that microwave method is an option that can reduce the time of decalcification. Tooth tissue morphology also was noted to be well preserved with 5% trichloracetic acid and 14% EDTA in comparison to 5% Nitric acid.

Effect of different trimline extension of clear aligners in combination with Class II elastics on the mandibular dentition: a finite element analysis

Effect of different trimline extension of clear aligners in combination with Class II elastics on the mandibular dentition: a finite element analysis

Mandibular Overdentures When Treating Failing Dentition With Immediate Prosthetic Loading.

Patients may present with failing mandibular dentition either involving the entire arch, partial arch that currently has a partial denture to replace the prior missing teeth or wearing a full denture. Finances may limit restoration of the arch with an All-on-X concept and the patient's goals are a stable prosthesis that does not move whenconcept and the patient's goals are a stable prosthesis that does not move when eating or speaking is the patient's expressed goal. Overdentures can fulfil that goal and provide a stable restored arch at a lower treatment cost than treatment with a fixed hybrid prosthesis. Traditionally, when these type cases have been treated, the remaining dentition has been extracted, depending on availability of bone, implants are placed. Those typically were left to osseointegrate and loaded several months later with a delayed loading approach. This requires relining the denture and the patient having a loose, non-stable prosthesis during that healing phase. An alternative approach utilizes immediate activation of the implants with overdenture attachments thus, providing an immediate stable retentive full arch mandibular removable prosthesis (overdenture) by immediate activation of overdenture attachments (ie.Locators) aids the patient in their goals without delays in treatment. This article will present two case examples of mandibular arches with failing dentition related to caries and periodontal issues and their treatment with immediate implant placement and loading with Locator attachments. Long-term follow-up of 1-year 8-months in one case and 33-months in the other case demonstrate crestal bone stability with this immediate overdenture loading protocol.

Advansync in management of class II malocclusion: A systematic review

Class II malocclusions are of interest to practising orthodontists since they constitute a significant percentage of the cases they treat. In individuals with Class II malocclusions, there is an anteroposterior discrepancy between the maxillary and mandibular dentitions, which is usually accompanied by a skeletal discrepancy. In such malocclusions, a functional appliance (myofunctional or fixed functional) is chosen as a treatment method depending on the severity and need of the particular case. This systematic review aims to evaluate the dental-alveolar, skeletal and soft tissue changes with the use of Advansync™ (A Class II corrector/ fixed functional appliance) in the treatment of Class II malocclusion. A literature search was done on Pubmed, EbscoHost , Google Scholar, Science Direct. This was conducted by two reviewers independently and any conflicts in results were managed through discussion. A Risk of Bias was done for the final articles included in the study. A total of 3,099 records were identified while searching through the database based on Mesh terms and search strategies. Based on the inclusion and exclusion criteria’s the total articles which were eligible for the systematic review were six. As the study was specific in terms of age and gender there was a high risk of selection bias but low risk of reporting bias.Out of the 6 studies, 5 had a low risk of bias and based on their cumulative findings, the effectiveness of Advansync is similar to those of other Class II correctors. The advantage of Advansync over other correctors is that the appliance saves treatment time and can be incorporated from the second month of treatment thereby shortening the duration of treatment.Fixed Class II correctors are used widely in Orthodontics. The selection of the appropriate appliance for the patient is the need of the hour. Thus, this systematic review gives us an insight on the use of Advansync in Class II correction.

Three-Dimensional Evaluation of Treatment Effects and Post-Treatment Stability of Maxillary Molar Intrusion Using Temporary Anchorage Devices in Open Bite Malocclusion.

Background: We investigated treatment outcomes and post-treatment stability in 10 patients with an anterior open bite and nonsurgical orthodontics. Methods: The patients underwent maxillary molar intrusion using temporary anchorage devices (TADs) to deepen the overbite due to mandibular autorotation. Lateral cephalograms and dental cast models were obtained before treatment (T0), immediately after it (T1), and >1 year after it (T2). Skeletal and dental cephalometric changes and three-dimensional movements of the maxillary dentitions were evaluated. Results: At T0, cephalometric analysis indicated that patients had skeletal class I with tendencies for a class II jaw relationship and a skeletal open bite. During active treatment (T0 to T1), the maxillary first molar intruded by 1.6 mm, the mandibular first molar extruded by 0.3 mm, the Frankfort-mandibular plane angle decreased by 1.1°, and the overbite increased by 4.1 mm. Statistically significant changes were observed in the amount of vertical movement of the maxillary first molar, Frankfort-mandibular plane angle, and overbite. Three-dimensional (3D) dental cast analysis revealed that the maxillary first and second molars intruded, whereas the anterior teeth extruded, with the second premolar as an infection point. In addition, the maxillary molar was tipped distally by 2.9° and rotated distally by 0.91°. Statistically significant changes were observed in the amount of vertical movement of the central incisor, lateral incisor, canine and first molar, and molar angulation. From T1 to T2, no significant changes in cephalometric measurements or the 3D position of the maxillary dentition were observed. The maxillary and mandibular dentitions did not significantly change during post-treatment follow-up. Conclusions: Maxillary molar intrusion using mini-screws is an effective treatment for open bite correction, with the achieved occlusion demonstrating 3D stability at least 1 year after treatment.

Biomechanical effects of clear aligner with different shape design at extraction space area during anterior teeth retraction.

This study aimed to investigate the biomechanical effects of clear aligner (CA) with different shape designs at extraction space (CAES) area during space closing. A finite-element method (FEM) model of mandibular dentition, periodontal ligaments, attachments, and corresponding CA was established. The connecting rod design of CAES was modelled for the control group. Eight test groups with different heights of CAES from -4 mm to +4 mm were designed. Tooth displacement tendencies were calculated. The maximum principal stress in PDLs, teeth, and CAs was analysed. Both global coordinate system and local coordinate system were also used to evaluate individual tooth movements. Across all groups, stresses concentrated on the lingual outer surface of CAESs. For the lowered CAES groups, both the stress value and the stress distribution area at CAESs were increased. The lowered CAES groups showed reduced movement in anterior teeth and less tipping tendency of the canines. The shape of CAES has a biomechanical impact on anterior teeth movement and should be considered in aligner design. The results suggest that increasing the height of CAES can enhance anterior teeth retraction, while lowered CAES may facilitate controlled root movement. Changes in the shape of CAES represent a potential direction for biomechanical improvement of clear aligner in extraction cases and are worth exploring.

Management regulations for odontogenic keratocyst: a case report and review of the literature

BackgroundReconstruction of the entire dentition with odontogenic keratocyst is a very challenging quandary. Most cases of odontogenic keratocyst are often reported to be benign, resulting in severe occlusal discrepancies with the maxillary and mandibular dentition. Dental radiographs occasionally reveal an uncommon, locally aggressive developing cyst termed as odontogenic keratocyst, which is typically located in the posterior jaw. When this cyst occurs in the anterior region, it is often misdiagnosed with other periapical lesions due to its lack of response to pulp vitality tests.Case presentationThis clinical case scenario demarcates the endodontic management of a patient diagnosed with odontogenic keratocyst. A 37-year-old Indian male patient reported to the department with throbbing pain in the lower left posterior tooth requiring endodontic therapy. This patient also presented with odontogenic keratocyst in the anterior region of the jaw, for which he had undergone surgical rehabilitation. This case report highlights the clinical protocol for the endodontic therapy in patient diagnosed with ododntogenic keratocyst. Masticatory impairment was not visible after the follow-up period and the treatment outcome was successful.ConclusionThis case report details the presentation, characteristic radiographic findings, and endodontic management of a patient with an extremely rare condition of odontogenic keratocyst. The management involves multidisciplinary approach for the rehabilitation.

Treatment of Vertical Maxillary Excess in Skeletal Class II Hyperdivergent Face Using Skeletal Anchorage—An IBO Case Report

This case report was presented at the Indian Board of Orthodontics (IBO) examination under category III in September 2022. It describes the case of 13-year-old female with hyperdivergent facial pattern and class II skeletal base, treated using microimplant anchorage. Patient presented with vertical maxillary excess, increased lower facial height, gummy smile, and incompetent lips. All four first premolar extraction treatments were planned with simultaneous retraction and intrusion of maxillary and mandibular dentition. The case was treated using 022 slot MBT prescription appliance. Lip exercises were prescribed to increase the tone of lips, which would aid in attainment of lip seal. Case was completed with class I molars, normal overjet–overbite, and improved smile aesthetics. The patient exhibited competent lips and reduced anterior–posterior gingival show.

A retrospective study of occlusal reconstruction in patients with old jaw fractures and dentition defects

PurposeThis study evaluated the methods and clinical effects of multidisciplinary collaborative treatment for occlusal reconstruction in patients with old jaw fractures and dentition defects. MethodsPatients with old jaw fractures and dentition defects who underwent occlusal reconstruction at the Third Affiliated Hospital of Air Force Military Medical University from January 2018 to December 2022 were enrolled. Clinical treatment was classified into 3 phases. In phase I, techniques such as orthognathic surgery, microsurgery, and distraction osteogenesis were employed to reconstruct the correct 3-dimensional (3D) jaw position relationship. In phase II, bone augmentation and soft tissue management techniques were utilized to address insufficient alveolar bone mass and poor gingival soft tissue conditions. In phase III, implant-supported overdentures or fixed dentures were used for occlusal reconstruction. A summary of treatment methods, clinical efficacy evaluation, comparative analysis of imageological examinations, and satisfaction questionnaire survey were utilized to evaluate the therapeutic efficacy in patients with traumatic old jaw fractures and dentition defects. All data are summarized using the arithmetic mean ± standard deviation and compared using independent sample t-tests. ResultsIn 15 patients with old jaw fractures and dentition defects (an average age of 32 years, ranging from 18 to 53 years), there were 7 cases of malocclusion of single maxillary fracture, 6 of malocclusion of single mandible fracture, and 2 of malocclusion of both maxillary and mandible fractures. There were 5 patients with single maxillary dentition defects, 2 with single mandibular dentition defects, and 8 with both maxillary and mandibular dentition defects. To reconstruct the correct 3D jaw positional relationship, 5 patients underwent Le Fort I osteotomy of the maxilla, 3 underwent bilateral sagittal split ramus osteotomy of the mandible, 4 underwent open reduction and internal fixation for old jaw fractures, 3 underwent temporomandibular joint surgery, and 4 underwent distraction osteogenesis. All patients underwent jawbone augmentation, of whom 4 patients underwent a free composite vascularized bone flap (26.66%) and the remaining patients underwent local alveolar bone augmentation. Free gingival graft and connective tissue graft were the main methods for soft tissue augmentation (73.33%).The 15 patients received 81 implants, of whom 11 patients received implant-supported fixed dentures and 4 received implant-supported removable dentures. The survival rate of all implants was 93.82%. The final imageological examination of 15 patients confirmed that the malocclusion was corrected, and the clinical treatment ultimately achieved occlusal function reconstruction. The patient satisfaction questionnaire survey showed that they were satisfied with the efficacy, phonetics, aesthetics, and comfort after treatment. ConclusionOcclusal reconstruction of old jaw fractures and dentition defects requires a phased sequential comprehensive treatment, consisting of 3D spatial jaw correction, alveolar bone augmentation and soft tissue augmentation, and implant-supported occlusal reconstruction, achieving satisfactory clinical therapeutic efficacy.

The Biomechanics of Clear Aligners associated with temporary skeletal anchorage devices (TSADs)

The treatment with aligners is challenging especially because the overall accuracy of tooth movement is reported to be below 50%. Moreover, dental anchorage provided by the CA is critical due to the third law of physics, where for every force action, there is an equal opposite reaction. CA associated with temporary skeletal anchorage devices (TSAD) are an effective treatment protocol for expanding the envelope of movement in complex cases. Extra-alveolar miniscrews associated with CA, are effective for retracting the maxillary (IZC) and mandibular dentition (MBS), while interradicular miniscrews provide excellent anchorage for incisor intrusion.Objective: The objective of the paper was to discuss the current biomechanics principles related to the use of CA associated with TSAD showcasing the treatment of complex cases, such as Class II, Class III, as well as deepbite malocclusions.

Mandibulotomy Technique and Permanent Molar Injury After Mandibular Distraction Osteogenesis in Infants.

The risk that mandibular distraction osteogenesis (MDO) poses to the developing mandibular dentition is well-known; however, less is understood about how the choice of instrumentation used for mandibular osteotomy might affect the development of permanent molars. Retrospective chart review examining infants with micrognathia who underwent MDO from 2010 to 2018 at a single tertiary care children's hospital using external, multivector devices. The first and second permanent mandibular molars were radiographically examined years after surgery to determine whether osteotomy cutting techniques affect the risk of injury to the permanent dentition. Thirty-seven infants and children underwent MDO from 2010 to 2018. Follow-up dental radiographs were available for 17 patients; 6 patients were excluded based on the use of preoperative computed tomography, utilization of virtual surgical planning technology, use of buried internal distractors, or older age at the time of distraction surgery. This yielded a total of 11 patients who underwent MDO with external hardware without virtual surgical planning representing 22 osteotomies. Sixteen osteotomies were performed using a side-cutting burr and 6 with a piezoelectric saw. The median age at distraction surgery was 3 weeks. The rate of an abnormal permanent first or second mandibular molar finding per osteotomy was 88% (14/16) in the side-cutting group versus 17% (1/6) with the piezoelectric technique (P = 0.004). Mandibular distraction osteogenesis risks injury to the mandibular molars; however, this study suggests a significant risk reduction in molar injury if the piezoelectric device is utilized.

Effects of different patterns of movement for correcting a deep curve of Spee with clear aligners on the anterior teeth: a finite element analysis

ObjectiveTo analyse the anterior teeth effects of clear aligners on five different patterns of mandibular molar movement and to define the most effective configuration to be implemented with clear aligners through finite element analysis.MethodsA three-dimensional mandibular model with a deep overbite in the mandible was constructed using cone beam computerized tomography (CBCT) data. The model included the mandibular dentition, mandibular periodontal ligaments, attachments, and aligners. Five models were created: (1) configuration A: second molar distalization (0.25 mm); (2) configuration B: second molar distalization (0.25 mm), first molar extrusion (0.15 mm); (3) configuration C: second molar distalization (0.25 mmm), first and second premolar extrusion(0.15 mm); (4) configuration D: second molar distalization (0.25 mm), first molar and first/second premolar extrusion(0.15 mm); and (5) configuration E: second molar distalization (0.25 mm), first molar and first/second premolar extrusion (0.15 mm), first molar and first/second premolar expansion (0.15 mm).ResultsIn all configurations, the anterior teeth exhibited labial tipping and the mandibular central incisor of configuration E showed the highest labial tipping. Configuration E demonstrated a relatively minor impact on mandibular molars distalization compared with configuration A. Configuration A showed the highest distal displacement value, and configuration E produced the lowest displacement value. Configuration E caused the highest periodontal ligament (PDL) pressure of the central and lateral incisors. The differences in the canines between configurations C and D,were not significant, and the stress distribution differed among the five groups.ConclusionsAll patterns utilizing clear aligners facilitated mandibular molar distalization. Extruding the premolars and second molar distalization at the same time had little impact on second molar distalization; When expansion and extrusion were simultaneously performed during the distalization of mandibular molars, our prime consideration was the alveolar bone on the labial side of the anterior teeth to prevent the occurrence of gingival recession, dehiscence, and fenestration. Due to the lack of consideration for periodontal tissues in this study, clinical protocols should be designed based on the periodontal status of the mandibular anterior teeth.

TADS assisted camouflage orthodontic treatment of class ii malocclusion in a non-growing patient- A case report

In individuals with Class II malocclusions, there is an anteroposterior discrepancy between the maxillary and mandibular dentitions, which may or may not be accompanied with a skeletal discrepancy, the most effective treatment option to eliminate is by modified three-piece base arch combined with TADS for simultaneous deep bite correction and en masse retraction.The present case report showcases the treatment results and biomechanics involved for en masse retraction and intrusion of anterior teeth using three-piece intrusion arch and temporary anchorage device.The modified three-piece base arch combined with TADS is effective in controlled translation and intrusion of anteriors and would be a preferable mechanotherapy in low angle case with deep bite, proclined anteriors and Class II malocclusion.

Comparison of posttreatment stability after total mandibular arch distalization with mini-implants and mandibular setback surgery.

To compare posttreatment stability in skeletal Class III patients between those treated by total mandibular arch distalization (TMAD) with buccal mini-implants and those by mandibular setback surgery (MSS). The samples included 40 Class III adults, 20 treated by TMAD using buccal interradicular mini-implants and 20 treated with MSS. Lateral cephalograms were taken at pretreatment, posttreatment, and at least 1-year follow-up, and 24 variables were compared using statistical analysis. Mandibular first molars moved distally 1.9 mm with intrusion of 1.1 mm after treatment in the TMAD group. The mandibular incisors moved distally by 2.3 mm. The MSS group exhibited a significant skeletal change of the mandible, whereas the TMAD group did not. During retention, there were no skeletal or dental changes other than 0.6 mm labial movement of the mandibular incisors (P < .05) in the MSS group. There was 1.4° of mesial tipping (P < .01) and 0.4 mm of mesial movement of the mandibular molars and 1.9° of labial tipping (P < .001) and 0.8 mm of mesial movement of the mandibular incisors in the TMAD group. These dental changes were not significantly different between the two groups. The TMAD group showed a slightly decreased overjet with labial tipping of the mandibular incisors and mesial tipping of the first molars during retention. Posttreatment stability of the mandibular dentition was not significantly different between the groups. It can be useful to plan camouflage treatment by TMAD with mini-implants in mild-to-moderate Class III patients.

The Root Complex in Posterior Teeth: A Direct Digital Analysis.

The aim of this morphometric study was to precisely determine the 3D characteristics of the root complex of the posterior dentition. Extracted and well-preserved permanent posterior teeth were included in this analysis and grouped based on tooth type and arch location. All teeth were digitally scanned. Morphologic and dimensional features of the root complex were assessed, including length and surface area of the root trunk and individual roots, width of root concavities (RC), and furcation entrance, when present. A total of 240 posterior teeth comprised the study sample. The root complex of multirooted maxillary first premolars presented with a long root trunk (10.49 mm), representing 65.52% of the surface area, and two short roots comprising the remaining 34.8% of the surface area. Root trunks of mandibular molars were an average of 0.8 mm shorter than their maxillary counterparts. Class III furcation involvement is expected in all maxillary and mandibular molars, as well as multirooted maxillary first premolars, after 4.80 mm and 10.49 mm of clinical attachment loss, respectively. RCs were a common finding among the evaluated dentitions. The root complex morphology varies among the maxillary and mandibular posterior dentition. RCs are highly prevalent in both maxillary and mandibular dentition. The findings derived from this study can be utilized in daily clinical practice for the adequate management of posterior dentition and serve as a reference for future investigations in dental anatomy and digital technology. Also, these findings can guide the industry into creating and redefining tools that adequately adapt to the anatomical characteristics and variations of the specific tooth type.