Search

When developing, the mandible presents great plasticity and contains condensed mesenchymal cells that develops into Meckel's cartilage, of which the anterior part forms the mandibular symphysis. Mandible human development studies focus on investigating whether the beginning of mandibular fusion in fetal period is related to symphysis ossification and the tensions imposed on it, considering that tongue movements, mouth opening, and closing can be seen in fetuses. This research analyses tissue modifications during human mandibular symphysis growth using light and scanning electron microscopy to relate them to its functional structure. The study sample consisted of 12 human fetuses distributed into two groups: Group I (GI) of 10–14 weeks old and Group II (GII) of 20–24 weeks old. Fragments of mandibular symphysis were removed en bloc together with the surrounding tissues to preserve the relation with adjacent structures. Decalcified specimens were prepared in semi‐serial coronal sections 5‐μm‐thick and stained with hematoxylin and eosin, Masson՚s trichrome, Verhoeff, and Sirius red for histological analysis with light microscopy. Collagen fibers Type I or III and elastic fibers were quantified by volume fraction (Vv). Coronal sections of the GI and GII symphyseal region were submitted to scanning electron microscopy. Comparison between groups used independent t‐test. Our study presents the different endochondral ossification stages in the anterior part of Meckel's cartilage in GI. Both groups showed abundantly vascularized mesenchymal tissue with intense cellular activity forming the mandibular symphysis, such as a source of new osteoblasts adjacent to the newly deposited bone matrix. Scanning electron microscopy analysis revealed an invasion of the bony trabecula in the transverse direction from the hemimandible, rectilinear in GI and sinuous in GII due to interdigitating bone process, promoting its ossification. In collagen Vv analysis was verified a prevalence of type I in GII and type III in GI, indicating a proportional relation between maturation and tissue arrangement. Functionally, the collagen and elastic fibers in the mandibular symphysis were arranged in a pantographic network, and the fibrillar interconnectivity clearly contributes to resilience capacity and efficiency of the force transfer. This study inferred the functional significance of the knowledge about the tissue composition of mandibular symphysis, and the importance of this tissue for surrounding structures. The mesenchymal tissue of mandibular symphysis participates in bone growth process, revealing an adaptation mechanism of mandibular symphysis in the fetal period investigated. [ABSTRACT FROM AUTHOR]

Masticatory muscle forces influence craniofacial morphology development. The antegonial notch (Notch) is a bony concavity on the inferior border of the mandible. Considering the Notch is located anteriorly to the insertion of the masseter muscle and varies among individuals, we hypothesised that these muscles influence the formation of the Notch. Therefore, this study aimed to investigate the correlation between mandible morphology and Notch formation. Sixty Japanese patients who visited the Department of Orthodontics at our university hospital were retrospectively evaluated. Morphological and morphometric analyses of the Notch and related craniofacial parameters were conducted using lateral cephalograms taken at the patients' initial visits. Standard values for the Notch area and depth were determined, and the morphology of the Notch and mandible was analysed using Spearman's rank correlation coefficient (p < 0.05). The mean Notch area and depth was 78.71 ± 36.54 mm2 and 3.11 ± 1.09 mm, respectively. The Notch area was significantly correlated with ramus inclination (p = 0.044, r = 0.261) and with the Y-axis (p = 0.039, r = 0.267). This study indicated that both the masticatory muscles and mandibular growth could contribute to the Notch formation. [ABSTRACT FROM AUTHOR]

Abstract Masticatory muscle forces influence craniofacial morphology development. The antegonial notch (Notch) is a bony concavity on the inferior border of the mandible. Considering the Notch is located anteriorly to the insertion of the masseter muscle and varies among individuals, we hypothesised that these muscles influence the formation of the Notch. Therefore, this study aimed to investigate the correlation between mandible morphology and Notch formation. Sixty Japanese patients who visited the Department of Orthodontics at our university hospital were retrospectively evaluated. Morphological and morphometric analyses of the Notch and related craniofacial parameters were conducted using lateral cephalograms taken at the patients’ initial visits. Standard values for the Notch area and depth were determined, and the morphology of the Notch and mandible was analysed using Spearman’s rank correlation coefficient (p

Copyright of Orthodontie Française is the property of John Libbey Eurotext Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objective This study aims to identify the presence, timing, and magnitude of a prepubertal mandibular growth spurt in a Class I and Class II population. Methods From the Burlington and Iowa Growth study of the AAOF Craniofacial Growth Legacy Collection, 83 Class I subjects (37 females and 46 males) and 32 Class II subjects (18 males and 14 females) were identified, as having at least seven consecutive annual lateral cephalograms taken from 5 to 11 years of age. Only subjects with a normodivergent facial pattern were considered. A customized cephalometric analysis was performed, and total mandibular length, defined as the distance between Condylion (Co) and Gnathion (Gn), was calculated. Results Overall, a significant early peak of mandibular growth was present in all the subjects analysed both in Class I (4.69 mm for males and 4.18 mm for females; P  < .05) and in Class II (5.85 mm for males and 4.05 mm for females; P  < .05). No differences between males and females were found for the timing of this peak (7 years for Class I and Class II females and 7 years for Class I and 6.5 years for Class II males). In males, a significantly larger peak was observed in Class II than Class I subjects (P  = .007). Limitations The main limitations of this study were the impossibility of using a suitable growth indicator to identify the timing of the early mandibular growth peak and the limited Class II records retrievable. Conclusion This investigation suggests that a prepubertal mandibular growth peak is consistently present in both Class I and Class II males and females of clinically significant magnitude. Despite that, chronological age confirms to be unsuitable to identify this peak. [ABSTRACT FROM AUTHOR]

Copyright of Revue d'Orthopédie Dento-Faciale is the property of Parresia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objective: To evaluate effect of growth hormone (GH) therapy in craniofacial development in children with or without growth hormone deficiency. Method: The systematic review was conducted by searching the electronic databases—PubMed, Cochrane clinical trials register, Google scholar, and EBSCO host. Randomized controlled trials and observational studies published till January 2022 were included. The risk of bias was assessed by Risk-Of-Bias VISualization (ROBVIS) tool. The risk of bias of the included studies was presented as a "traffic light" plot of individual studies and a summary diagram. Data was studied by two authors and any dispute was resolved by another reviewer. Result: A total of 964 articles were obtained through electronic database search. After eliminating the duplicates, 13 articles met inclusion criteria. Of the 13 studies, 8 studies had moderate risk of bias, 2 had serious risk of bias, and 1 had critical risk of bias as per the ROBINS-I assessment. According to the RoB 2, two studies were having high risk of bias. Conclusion: The maxillary length, the mandibular length, and the cranial base length increased post-GH therapy, causing an overall increase in the facial height. The limitation of GH therapy was in the transverse direction as maxillary and mandibular arch dimensions remained almost equal to those in the untreated subjects. Dentition had minimal influence of GH therapy. Registration: The systematic review was registered in the International Prospective Register of Systematic Reviews database under CRD42021257044. [ABSTRACT FROM AUTHOR]

The goal of this study was to create a novel machine learning (ML) model that can predict the magnitude and direction of pubertal mandibular growth in males with Class II malocclusion. Lateral cephalometric radiographs of 123 males at three time points (T1: 12; T2: 14; T3: 16 years old) were collected from an online database of longitudinal growth studies. Each radiograph was traced, and seven different ML models were trained using 38 data points obtained from 92 subjects. Thirty-one subjects were used as the test group to predict the post-pubertal mandibular length and y-axis, using input data from T1 and T2 combined (2 year prediction), and T1 alone (4 year prediction). Mean absolute errors (MAEs) were used to evaluate the accuracy of each model. For all ML methods tested using the 2 year prediction, the MAEs for post-pubertal mandibular length ranged from 2.11–6.07 mm to 0.85–2.74° for the y-axis. For all ML methods tested with 4 year prediction, the MAEs for post-pubertal mandibular length ranged from 2.32–5.28 mm to 1.25–1.72° for the y-axis. Besides its initial length, the most predictive factors for mandibular length were found to be chronological age, upper and lower face heights, upper and lower incisor positions, and inclinations. For the y-axis, the most predictive factors were found to be y-axis at earlier time points, SN-MP, SN-Pog, SNB, and SNA. Although the potential of ML techniques to accurately forecast future mandibular growth in Class II cases is promising, a requirement for more substantial sample sizes exists to further enhance the precision of these predictions. [ABSTRACT FROM AUTHOR]

Abstract Background It is difficult for orthodontists to accurately predict the growth trend of the mandible in children with anterior crossbite. This study aims to develop a deep learning model to automatically predict the mandibular growth result into normal or overdeveloped using cephalometric radiographs. Methods A deep convolutional neural network (CNN) model was constructed based on the algorithm ResNet50 and trained on the basis of 256 cephalometric radiographs. The prediction behavior of the model was tested on 40 cephalograms and visualized by equipped with Grad-CAM. The prediction performance of the CNN model was compared with that of three junior orthodontists. Results The deep-learning model showed a good prediction accuracy about 85%, much higher when compared with the 54.2% of the junior orthodontists. The sensitivity and specificity of the model was 0.95 and 0.75 respectively, higher than that of the junior orthodontists (0.62 and 0.47 respectively). The area under the curve value of the deep-learning model was 0.9775. Visual inspection showed that the model mainly focused on the characteristics of special regions including chin, lower edge of the mandible, incisor teeth, airway and condyle to conduct the prediction. Conclusions The deep-learning CNN model could predict the growth trend of the mandible in anterior crossbite children with relatively high accuracy using cephalometric images. The deep learning model made the prediction decision mainly by identifying the characteristics of the regions of chin, lower edge of the mandible, incisor teeth area, airway and condyle in cephalometric images.

Abstract Background This study aimed to compare spheno-occipital synchondrosis (SOS) maturation stages with a three-dimensional assessment of mandibular growth. Methods This is a cross-sectional study of a retrospective type, in which cone-beam computed tomography (CBCT) images of 500 patients aged 6 to 25 years (226 males and 274 females) were analyzed. The SOS was evaluated using the four-stage scoring system; completely open, partially fused, semi-fused, or completely fused. The SOS scoring and three-dimensional cephalometric measurements were analyzed by Invivo 6.0.3 software. Descriptive and analytical statistics were performed, and a P-value

Simple Summary: Facial symmetry is a crucial determinant of facial appearance; treatment of asymmetry can be challenging. When it comes to the mandible's development the muscles play a significant role in the development and growth direction of the mandible. However, it is unclear how the masticatory muscles contribute to early facial development, nor do we know to what extent they are involved in asymmetry. Our objective was to investigate the impact of masseter resection on mandibulofacial growth by reviewing the data of previously published studies on rats up to October 2022. The results of this study provide evidence that experimental masseter muscle excision in developing rats causes atrophic changes in the angular process, asymmetry in the maxilla, and overall shortening of the mandible. These changes occur as a direct outcome of the removal of the masseter muscle. Due to the mandible's posterior rotation, muscular excision did cause specific articular alterations in the temporomandibular joint. Lateral X-rays of the mandible of the rats who were part of the experimental group revealed that their mandibular plane angles were higher than those of the control group. An individual's facial appearance is heavily influenced by facial symmetry. In the asymmetric mandible, periosteal apposition and endochondral ossification in one of the condyles may stimulate asymmetric growth of the body. Our aim was to review the impact on the growth following masseter resection. Relevant studies up to October 2022 were retrieved from PubMed, Scopus, and Web of Science. The PICOS method was utilized to determine eligibility, and the SYRCLE risk of bias tool was utilized to provide an estimate of potential bias. A predetermined algorithm was used to search the databases. The results of our systematic review of seven studies indicate that the masseter muscle strongly impacts craniofacial growth and development. Resection of the masseter muscle significantly reduces the sagittal and vertical development of the jaw in rats. In addition, the masseter muscle excision influences the mandibular morphology, including the condylar area, angle, and development direction of the jaw. [ABSTRACT FROM AUTHOR]

The aim of these two case-reports is to illustrate and compare the therapeutic effects of Class II elastics in combination with F22 aligners in an adult and an adolescent patient, respectively. Two patients with a mild skeletal Class II malocclusion, associated with mild-to-moderate crowding, presented for orthodontic treatment. The first patient was 12 years old, while the second was 40 years old. In both cases, the goal was to obtain bilateral molar and canine Class I with ideal overjet and overbite, and Class II skeletal relationship improvement in the young patient as well. Both treatments were approached without extractions and using clear aligners (CAs) in combination with Class II elastics, giving the patient the opportunity to take advantage of a therapy that is both comfortable and aesthetic. Final records of both cases demonstrate how appropriate analysis and diagnosis enable CAs in conjunction with Class II elastics to be used with considerable efficiency and efficacy for Class II treatment. In the first case, the key to success was exploiting residual jaw growth, while in the second case it was careful orthodontic digital planning. In the presence of good patient compliance, CAs associated with Class II elastics provide satisfactory occlusal outcomes if biomechanics and digital set-up are carefully evaluated and executed and if diagnosis is appropriate. [ABSTRACT FROM AUTHOR]

Background: This study aimed to compare spheno-occipital synchondrosis (SOS) maturation stages with a three-dimensional assessment of mandibular growth. Methods: This is a cross-sectional study of a retrospective type, in which cone-beam computed tomography (CBCT) images of 500 patients aged 6 to 25 years (226 males and 274 females) were analyzed. The SOS was evaluated using the four-stage scoring system; completely open, partially fused, semi-fused, or completely fused. The SOS scoring and three-dimensional cephalometric measurements were analyzed by Invivo 6.0.3 software. Descriptive and analytical statistics were performed, and a P-value < 0.05 was considered statistically significant. Results: There was a statistically significant difference in mandibular measurements among SOS maturation stages in both sexes (P < 0.05). The skeletal growth increments of mandibular variables across the SOS stages had higher mean differences between SOS stages 2 and 3 than those between stages 1 and 2 and stages 3 and 4 in both sexes. The mandibular growth curves increased with chronological age (earlier in females) and SOS maturation stages (mostly in stages 1, 2, and 3 than stage 4). Conclusions: The SOS maturation stages are valid and reliable mandibular skeletal indicators as evaluated with three-dimensional cephalometric mandibular measurements. The findings of growth increments and constructed growth curves of mandibular growth might be helpful in diagnosis and treatment planning. [ABSTRACT FROM AUTHOR]

Estrogen is a steroid hormone that induces skeletal growth and affects endochondral ossification of the long tubular bone growth plate during the growth period. However, the effects of estrogen on endochondral ossification of the mandibular condylar cartilage are unclear. In this study, ovariectomized Wistar/ST rats were used to investigate the longitudinal effects of estrogen on mandibular growth. The rats were administered different doses of estrogen. Longitudinal micro-computed tomographic scanning, histological staining and ELISA on plasma growth hormone were performed to examine the effects of estrogen on mandibular growth. The results showed that mandibular growth was suppressed throughout the growth period by estrogen in a dose-dependent manner. In addition, long-term administration of a high dose of estrogen to the rats resulted in significant increase in growth hormone throughout the growth period, significant circularization of cell nuclei in the proliferative layer, intensely staining cartilage matrix in the subchondral bone, and significant suppression of estrogen receptor (ER) alpha and beta expression in the mandibular cartilage. However, regardless of estrogen concentration, in the posterior part of the mandibular cartilage, ER expression extended to both the hypertrophic and proliferative layers. These results indicate that estrogen suppresses mandibular growth throughout the growth period. Additionally, it influences endochondral ossification via its effect on ERs. [Display omitted] • Estrogen inhibits mandibular growth throughout the growth period. • Estrogen promotes cartilage matrix production during subchondral bone formation. • Estrogen receptor (ER) regulates mandibular condylar cartilage (MCC) growth. • ER expression extended to both the proliferative and prehypertrophic layers in the posterior part of the MCC. [ABSTRACT FROM AUTHOR]

Introduction: Cooperation and choice of device are not sufficient to predict the success of interceptive treatment in Class II, 1. The aim of this study was to identify specific factors of patient morphology that predict success., Material and Methods: A retrospective, prognostic, comparative, monocentric, intention-to-treat study was carried out. The criterion for therapeutic success was normalization of the ANB. The success and failure groups were statistically compared with an alpha risk of 5%., Results: 95 patients who underwent interceptive treatment close to their growth peak were included. The probability of successful treatment was a decreasing function of FMA, SNA, ANB and IMPA and an increasing function of SNB, ramus height and mandibular length. The proposed logistic equation offers a sensitivity of 82% and a specificity of 87%., Discussion: Hyperdivergence below surgical values is not a factor in mandibular response failure. Hypodivergence is a factor in success. A stocky mandible (large ascending ramus, large horizontal ramus) responds well. Rather than ramus height, mandibular length is decisive: the greater the retromandibular height, the greater the chances of success. Pre-existing mandibular incisor vestibuloversion is a factor in failure., Conclusion: The accumulation of negative predictive factors may point towards an alternative therapeutic solution or prompt the patient and family to be informed of the difficulties inherent in the treatment.

The goal of this study was to create a novel machine learning (ML) model that can predict the magnitude and direction of pubertal mandibular growth in males with Class II malocclusion. Lateral cephalometric radiographs of 123 males at three time points (T1: 12; T2: 14; T3: 16 years old) were collected from an online database of longitudinal growth studies. Each radiograph was traced, and seven different ML models were trained using 38 data points obtained from 92 subjects. Thirty-one subjects were used as the test group to predict the post-pubertal mandibular length and y-axis, using input data from T1 and T2 combined (2 year prediction), and T1 alone (4 year prediction). Mean absolute errors (MAEs) were used to evaluate the accuracy of each model. For all ML methods tested using the 2 year prediction, the MAEs for post-pubertal mandibular length ranged from 2.11–6.07 mm to 0.85–2.74° for the y-axis. For all ML methods tested with 4 year prediction, the MAEs for post-pubertal mandibular length ranged from 2.32–5.28 mm to 1.25–1.72° for the y-axis. Besides its initial length, the most predictive factors for mandibular length were found to be chronological age, upper and lower face heights, upper and lower incisor positions, and inclinations. For the y-axis, the most predictive factors were found to be y-axis at earlier time points, SN-MP, SN-Pog, SNB, and SNA. Although the potential of ML techniques to accurately forecast future mandibular growth in Class II cases is promising, a requirement for more substantial sample sizes exists to further enhance the precision of these predictions.

An individual’s facial appearance is heavily influenced by facial symmetry. In the asymmetric mandible, periosteal apposition and endochondral ossification in one of the condyles may stimulate asymmetric growth of the body. Our aim was to review the impact on the growth following masseter resection. Relevant studies up to October 2022 were retrieved from PubMed, Scopus, and Web of Science. The PICOS method was utilized to determine eligibility, and the SYRCLE risk of bias tool was utilized to provide an estimate of potential bias. A predetermined algorithm was used to search the databases. The results of our systematic review of seven studies indicate that the masseter muscle strongly impacts craniofacial growth and development. Resection of the masseter muscle significantly reduces the sagittal and vertical development of the jaw in rats. In addition, the masseter muscle excision influences the mandibular morphology, including the condylar area, angle, and development direction of the jaw.

Objectives: Dentofacial orthopaedic treatment of mandibular hypoplasia has unpredictable skeletal outcomes. Although several biomodulators including insulin‐like growth factor 1 (IGF‐1) are known to contribute to chondrocyte proliferation, their efficacy in modulating mandibular growth has not been validated. The aim of this study was to determine the effect of locally delivered IGF‐1 on mandibular growth and condylar bone quality/quantity in juvenile rats. Setting and sample population: Institutional vivarium using twenty‐four 35‐day‐old male Sprague‐Dawley rats. Methods: PBS or 40 µg/kg (low‐dose) IGF‐1 or 80 µg/kg (high‐dose) IGF‐1 was injected bilaterally into the temporomandibular joints of the rats at weekly intervals for four weeks. Cephalometric and micro‐computed tomography measurements were used to determine mandibular dimensions. Bone and tissue mineral density, volume fraction and mineral content were determined, and serum IGF‐1 concentrations assayed. Results: Intra‐articular administration of high‐dose IGF‐1 contributed to a significant 6%‐12% increase in mandibular body and condylar length compared to control and low‐dose IGF‐1‐treated animals. Additionally, IGF‐1 treatment resulted in a significant decrease in the angulation of the lower incisors to mandibular plane. Condylar bone volume, bone volume fraction, mineral content and mineral density were significantly increased with high‐dose IGF‐1 relative to control and low‐dose IGF‐1 groups. Serum IGF‐1 levels were similar between all groups confirming limited systemic exposure to the locally administered IGF‐1. Conclusion: Local administration of high‐dose 80 µg/kg IGF‐1 enhances mandibular growth and condylar bone quality and quantity in growing rats. The findings have implications for modulating mandibular growth and potentially enhancing condylar bone health and integrity. [ABSTRACT FROM AUTHOR]

Mandibular protrusion and its treatment is challenging for the orthodontist. The aim of the present research was to identify macroscopic changes in the mandible, based on three-dimensional Cone Beam Computed Tomography analysis. Seventy-two male Wistar rats were divided into two equal groups, experimental (group A) and control (group B). Each consisted of three equal subgroups of 12 rats (A1, A2, A3, B1, B2, B3). Full-cast orthodontic intraoral devices were attached to the maxillary incisors of the experimental animals, and effected functional posterior mandibular displacement. Throughout the experimental period, all animals were fed with mashed food. Animals were sacrificed at 30 days (A1, B1), 60 days (A2, B2) and 90 days (A3, B3). At the 60th day of the experiment, the orthodontic devices were removed from the remaining experimental subgroup A3. Measurements revealed significant differences in the anteroposterior dimensions between experimental and control subgroups. However, the observed changes in the vertical dimensions, Condylion/Go'–Menton and the Intercondylar distance proved insignificant. Posterior mandibular displacement of the mandible in growing rats affects the morphology of the mandible and culminates in the development of a smaller mandible at a grown age. [ABSTRACT FROM AUTHOR]

Abstract Background With the aid of implants, Björk identified two-dimensional mandibular stable structures in cephalograms during facial growth. However, we do not know what the three-dimensional stable structures are with certainty. The purpose of this study was to identify the most stable mandibular landmarks in growing patients using three-dimensional images. Methods The sample was comprised of two cone-beam computed tomography (CBCT) scans taken about 4.6 years apart in 20 growing patients between the ages of 12.5 (T1) and 17.1 years (T2). After head orientation, landmarks were located on the chin (Pog), internal symphysis (Points C, D and E), and mandibular canals, which included the mental foramina (MF and MFA) and mandibular foramina (MdF). The linear distance change between Point C and these landmarks was measured on each CBCT to test stability through time. The reliability of the suggested stable landmarks was also evaluated. Results The total distance changes between Point C and points D, E, Pog, MF, and MFA were all less than 1.0 mm from T1 to T2. The reliability measures of these landmarks, which were measured by the Cronbach alpha, were above 0.94 in all three dimensions for each landmark. From T1 to T2, the distance changes from Point C to the right and left mandibular foramina were 3.39 ± 3.29 mm and 3.03 ± 2.83 mm, respectively. Conclusions During a growth period that averaged 4.6 years, ranging from 11.2 to 19.8 years old, the structures that appeared relatively stable and could be used in mandibular regional superimpositions included Pog, landmarks on the inferior part of the internal symphysis, and the mental foramen. The centers of the mandibular foramina and the starting points of the mandibular canal underwent significant changes in the transverse and sagittal dimensions.

Objective: The effects of unilateral increased occlusal vertical dimension (iOVD) on bilateral craniofacial, mandibular and alveolar development in growing rats were investigated via cone-beam computed tomography (CBCT). The role of Wnt/β-catenin signalling in this process was examined., Materials and Methods: Forty-eight female Sprague-Dawley rats were randomly allocated into unilateral iOVD and sham groups. At 2, 4 and 8 weeks, the rats were scanned via CBCT to analyse cranial, maxillary, mandibular and dental morphology. Changes in temporomandibular joint (TMJ) cartilage histology and Wnt/β-catenin signalling were assessed by histochemical and immunohistochemical staining and qRT-PCR., Results: Dorsal cephalograms revealed that the mandible in the iOVD group tilted approximately 4° to the right. Unilateral iOVD had little effect on cranial and maxillary growth but inhibited mandibular growth (mandibular length and ramal height), especially on the deviated side (DS). Moreover, unilateral iOVD increased the length of the lower incisors and decreased the height of the molars on the DS. Unilateral iOVD induced bilateral osteoarthritis-like changes in the bilateral TMJ condylar cartilage and activated Wnt/β-catenin signalling in the condylar cartilage, especially on the contralateral side (CLS)., Conclusion: Occlusion with unilateral iOVD induced mandibular deviation, significantly inhibited mandibular growth and produced compensatory changes in the alveolar bone. In the iOVD group, the mandibular body length and ramal height were greater on the CLS than on the DS. Moreover, the greater β-catenin protein expression in the TMJ condylar cartilage on the CLS than on the DS may account for the difference in asymmetrical mandibular development., (© 2024 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Cleft palate, a common global congenital malformation, occurs due to disturbances in palatal growth, elevation, contact, and fusion during palatogenesis. The Fibroblast growth factor 9 (FGF9) mutation has been discovered in humans with cleft lip and palate. Fgf9 is expressed in both the epithelium and mesenchyme, with temporospatial diversity during palatogenesis. However, the specific role of Fgf9 in palatogenesis has not been extensively discussed. Herein, we used Ddx4-Cre mice to generate an Fgf9–/– mouse model (with an Fgf9 exon 2 deletion) that exhibited a craniofacial syndrome involving a cleft palate and deficient mandibular size with 100% penetrance. A smaller palatal shelf size, delayed palatal elevation, and contact failure were investigated to be the intrinsic causes for cleft palate. Hyaluronic acid accumulation in the extracellular matrix (ECM) sharply decreased, while the cell density correspondingly increased in Fgf9–/– mice. Additionally, significant decreases in cell proliferation were discovered in not only the palatal epithelium and mesenchyme but also among cells in Meckel’s cartilage and around the mandibular bone in Fgf9–/– mice. Serial sections of embryonic heads dissected at embryonic day 14.5 (E14.5) were subjected to craniofacial morphometric measurement. This highlighted the reduced oral volume owing to abnormal tongue size and descent, and insufficient mandibular size, which disturbed palatal elevation in Fgf9–/– mice. These results indicate that Fgf9 facilitates palatal growth and timely elevation by regulating cell proliferation and hyaluronic acid accumulation. Moreover, Fgf9 ensures that the palatal elevation process has adequate space by influencing tongue descent, tongue morphology, and mandibular growth.

To determine the additive genetic and environmental contributions to the vertical growth of craniofacial structures. The sample consisted of 64 untreated monozygotic (44 male, 20 female) and 61 untreated dizygotic twins (32 male, 29 female). Lateral cephalograms taken at 15 and 18 years of age were traced to analyze the sella-nasion–nasal line angle (SN-NL), nasal line–mandibular line angle (ML-NL), sella-nasion–mandibular line angle (SN-ML), sella-nasion–sella-gnathion angle (Y-axis), posterior face height/anterior face height (PFH/AFH), and lower anterior face height/anterior face height (LAFH/AFH). The genetic and environmental components of variance were analyzed with structural equation modeling for multilevel mixed effects. At 15 years of age, strong dominant genetic control was seen for NL-ML (81%), LAFH/AFH (73%), and Y-axis (57%), whereas strong additive genetic components were found for PFH/AFH (78%), SN-NL (58%), and SN-ML (57%). Unique environmental factors accounted for 18–42% of observed variance, with SN-NL being affected the most (42%). At 18 years of age, only LAFH/AFH (86%) was under strong dominant genetic control, whereas the remainder were under additive genetic influence. The sole exception was SN-NL, which changed from additive to unique environmental influence. Either additive or dominant genetic components were found at 15 or 18 years of age for most vertical variables. Environmental factors accounted for about 10–40%, with SN-NL being mostly affected. [ABSTRACT FROM AUTHOR]

Cleft palate, a common global congenital malformation, occurs due to disturbances in palatal growth, elevation, contact, and fusion during palatogenesis. The Fibroblast growth factor 9 (FGF9) mutation has been discovered in humans with cleft lip and palate. Fgf9 is expressed in both the epithelium and mesenchyme, with temporospatial diversity during palatogenesis. However, the specific role of Fgf9 in palatogenesis has not been extensively discussed. Herein, we used Ddx4-Cre mice to generate an Fgf9–/– mouse model (with an Fgf9 exon 2 deletion) that exhibited a craniofacial syndrome involving a cleft palate and deficient mandibular size with 100% penetrance. A smaller palatal shelf size, delayed palatal elevation, and contact failure were investigated to be the intrinsic causes for cleft palate. Hyaluronic acid accumulation in the extracellular matrix (ECM) sharply decreased, while the cell density correspondingly increased in Fgf9–/– mice. Additionally, significant decreases in cell proliferation were discovered in not only the palatal epithelium and mesenchyme but also among cells in Meckel's cartilage and around the mandibular bone in Fgf9–/– mice. Serial sections of embryonic heads dissected at embryonic day 14.5 (E14.5) were subjected to craniofacial morphometric measurement. This highlighted the reduced oral volume owing to abnormal tongue size and descent, and insufficient mandibular size, which disturbed palatal elevation in Fgf9–/– mice. These results indicate that Fgf9 facilitates palatal growth and timely elevation by regulating cell proliferation and hyaluronic acid accumulation. Moreover, Fgf9 ensures that the palatal elevation process has adequate space by influencing tongue descent, tongue morphology, and mandibular growth. [ABSTRACT FROM AUTHOR]

Aim: Two-phase treatment for children with Class II malocclusion with several functional appliances is still performed by many orthodontists, while the Activator and the Bionator appliances are two of the most popular ones. Aim of this study was to compare the skeletal and dentoalveolar effects of treatment with these two appliances., Methods: Class II children treated with Activator or Bionator in the first phase, followed by a phase of fixed appliances were included. Skeletal and dentoalveolar parameters were assessed from lateral cephalograms and analysed with linear regressions at 5%., Results: A total of 89 patients (mean age 10.0 years; 47% female) were included. During the first phase, Bionator increased less the SNB (difference in mean treatment-induced changes [MD] -0.7°; 95% confidence interval [CI] -1.3 to -0.2°; P=0.01) and decreased less the ANB angle (MD 0.6°; 95% CI 0 to 1.1°; P=0.03) compared to Activator. Activator slightly increased the facial axis and Bionator reduced it (MD -1.6°; 95% CI -2.3 to -0.8°; P<0.001). Compared to Activator, the Bionator retroclined more the upper incisors (MD -2.4°; 95% CI -4.6 to -0.2°; P=0.03) and increased more the interincisal angle (MD 2.9°; 95% CI 0.5 to 5.4°; P=0.02). After the second phase (6.2 years after baseline), the only differences were a reduced facial axis (MD -1.3°; 95% CI -2.2 to -0.3°; P=0.008) and an increased maxillary rotation (MD 0.9°; 95% CI 0 to 1.8°; P=0.04) with Bionator compared to Activator., Conclusion: Similar dentoalveolar effects were seen overall with two-phase treatment with either appliance, with Bionator being associated with more vertical increase compared to Activator., (Copyright © 2024 The Author(s). Published by Elsevier Masson SAS.. All rights reserved.)

Mandibular protrusion and its treatment is challenging for the orthodontist. The aim of the present research was to identify macroscopic changes in the mandible, based on three-dimensional Cone Beam Computed Tomography analysis. Seventy-two male Wistar rats were divided into two equal groups, experimental (group A) and control (group B). Each consisted of three equal subgroups of 12 rats (A1, A2, A3, B1, B2, B3). Full-cast orthodontic intraoral devices were attached to the maxillary incisors of the experimental animals, and effected functional posterior mandibular displacement. Throughout the experimental period, all animals were fed with mashed food. Animals were sacrificed at 30 days (A1, B1), 60 days (A2, B2) and 90 days (A3, B3). At the 60th day of the experiment, the orthodontic devices were removed from the remaining experimental subgroup A3. Measurements revealed significant differences in the anteroposterior dimensions between experimental and control subgroups. However, the observed changes in the vertical dimensions, Condylion/Go’–Menton and the Intercondylar distance proved insignificant. Posterior mandibular displacement of the mandible in growing rats affects the morphology of the mandible and culminates in the development of a smaller mandible at a grown age.

Abstract Objectives This finite element analysis was conducted to study the effects produced by a new fixed functional appliance (EFA; Elhiny functional appliance) and hence predict its clinical effectiveness. Materials/methods Under ANSYS environment, a simplified 2D finite element model was prepared for this study. The models simulated a clinical situation where the mandible was positioned forward via a new fixed functional appliance design. The models’ components were created on a commercial CAD/CAM package then imported to finite element software. Pushing load of 2 N was applied along the appliance longitudinal direction. Results The mandible showed downward and forward deformation in the X and Y directions with the highest deformation at the symphysis and lower border with a total deformation of 80 μm. There was little deformation in the maxilla. The highest strain results were at the condyle, both compressive and tensile in the X and Y directions with a total of 1520 micro strain behind the condyle. The strain in the mandibular tooth bearing area was around zero and in the maxillary tooth bearing area ranged from − 9 to 16.6 micro strain. Conclusions Within the limitations of this finite element analysis, it could be predicted that the new appliance (EFA) produces pure functional skeletal results with absolutely no dentoalveolar effects, which provides the opportunity for observing significant skeletal changes.

This study compares long-term mandibular growth between a group of Beckwith-Wiedemann Syndrome (BWS) patients who underwent glossectomy at an early age and a group of patients not operated. Cephalometric measurements were performed in BWS patients comparing the data obtained between a group of patients operated at an early age and a group of non-operated patients who declined surgery. Statistics included independent sample T-test. Twenty-four out of 78 BWS patients followed since birth completed longitudinal cephalometric x-rays at age 5, 10 and 15. Eighteen patients needed early surgery. Eleven families accepted glossectomy at 2.3 ± 1.3 years of age; seven declined surgery. No differences in mandibular growth were found between the two groups. Inclination of maxillary incisors results were statistically greater in the non-operated group (operated compared to the non-operated group: 103.58 ± 11.30 Vs 108.98 ± 12.47; p-value 0.0168 at 5; 107.06 ± 7.98 Vs 115.14 ± 7.05; p-value 0.0206 at 10; 109.80 ± 4.68 Vs 116.75 ± 5.28; p-value 0.0233 at 15). Macroglossia has no role in the post-natal mandibular overgrowth in BWS and mandibular overgrowth is part of the syndrome. Therefore, early glossectomy does not change mandibular growth and does not prevent the development of class III skeletal malocclusion in these patients. [ABSTRACT FROM AUTHOR]

Background: With the aid of implants, Björk identified two-dimensional mandibular stable structures in cephalograms during facial growth. However, we do not know what the three-dimensional stable structures are with certainty. The purpose of this study was to identify the most stable mandibular landmarks in growing patients using three-dimensional images. Methods: The sample was comprised of two cone-beam computed tomography (CBCT) scans taken about 4.6 years apart in 20 growing patients between the ages of 12.5 (T1) and 17.1 years (T2). After head orientation, landmarks were located on the chin (Pog), internal symphysis (Points C, D and E), and mandibular canals, which included the mental foramina (MF and MFA) and mandibular foramina (MdF). The linear distance change between Point C and these landmarks was measured on each CBCT to test stability through time. The reliability of the suggested stable landmarks was also evaluated. Results: The total distance changes between Point C and points D, E, Pog, MF, and MFA were all less than 1.0 mm from T1 to T2. The reliability measures of these landmarks, which were measured by the Cronbach alpha, were above 0.94 in all three dimensions for each landmark. From T1 to T2, the distance changes from Point C to the right and left mandibular foramina were 3.39 ± 3.29 mm and 3.03 ± 2.83 mm, respectively. Conclusions: During a growth period that averaged 4.6 years, ranging from 11.2 to 19.8 years old, the structures that appeared relatively stable and could be used in mandibular regional superimpositions included Pog, landmarks on the inferior part of the internal symphysis, and the mental foramen. The centers of the mandibular foramina and the starting points of the mandibular canal underwent significant changes in the transverse and sagittal dimensions. [ABSTRACT FROM AUTHOR]

Objective: The aims of this longitudinal analysis of untreated monozygotic and dizygotic twins were to investigate vertical changes of the craniofacial structures during growth, to determine the concordance between genetically twins and to assess the genetic component for the various aspects of vertical growth.Settings and Sample Population: The sample consisted of 34 pairs of untreated monozygotic twins (23 male, 11 female) and 30 untreated dizygotic siblings of multiple birth (8 male, 8 female and 14 mixed) from the Forsyth Moorrees Twin Study (1959-1975); lateral cephalograms taken from 6 to 18 years of age were analysed at 3-year intervals.Materials and Methods: Cephalograms were traced, and longitudinal changes between twins in six angular and proportional vertical cephalometric variables (SN-NL, ML-NL, SN-ML, y-axis, PFH/AFH and LAFH/AFH) were analysed with intraclass correlation coefficients and linear regression modelling.Results: The concordance between monozygotic/dizygotic twins at 18 years of age was moderate to high with intraclass correlation coefficient values between 0.51 and 0.66. Additionally, sex differences in concordance at 18 years of age were found for three variables. High heritability (66%-79%) was observed for 5 of the 6 variables (LAFH/AFH, ML-NL, y-axis, SN-ML, PFH/AFH), while SN-NL showed limited heritability (34%).Conclusions: Although monozygotic/dizygotic twins share at least part of their genetic material, differences in the vertical dimension were found. This supports the complex developmental mechanism of the human face and the varying influence of genetic and environmental factors. [ABSTRACT FROM AUTHOR]

Objectives: Here, we quantify and compare the cross‐sectional shape of the mandibular corpus between M1 and M2 during growth in Pan paniscus, Pan troglodytes, and Pongo pygmaeus. The goal is to assess the hypothesis that the shape of the corpus is influenced by the development of permanent molars in their crypts, by examining ontogenetic changes in corpus shape and investigating covariation between corpus shape and M2 and M3 molar crypt forms. Materials and Methods: Ontogenetic changes in mandibular corpus shape were assessed using landmarks and semilandmarks, and measurements of length, width, and height were used to quantify molar crypts (M2 and M3). Ontogenetic changes in corpus growth from the eruption of M1 to the eruption of M3 were evaluated for each species through generalized Procrustes analysis and principal components analysis in shape–space and form–space. The relationship between corpus shape and molar crypt form was investigated at three different developmental stages using two‐block partial least squares (2B‐PLS) analysis. Results: The results show clear differences in growth patterns among all three species and provide evidence that species‐level differences in mandibular corpus growth occur prior to the emergence of M1. The results of the 2B‐PLS analysis reveal that significant covariance between corpus shape and molar crypt form is limited to the developmental stage marked by the emergence of M1, with covariance between corpus shape and M2 crypt width. Corpora that are relatively narrower in the inferior portion of the cross section covary with relatively narrower M2 crypts. Conclusions: These results have important implications for understanding the taxonomic and phylogenetic significance of mandibular corpus shape variation in the hominoid fossil record. [ABSTRACT FROM AUTHOR]

Palatal shelf elevation is an essential morphogenetic process that results from palatal shelf movement caused by an intrinsic elevating force. The nature of the elevating force remains unclear, but the accumulation of hyaluronic acid (HA) in the extracellular matrix (ECM) of the palatal shelves may play a pivotal role in developing the elevating force. In mammals, HA is synthesized by hyaluronic acid synthases (HAS) that are encoded by three genes (Has1-3). Here, we used the Wnt1-Cre driver to conditionally disrupt hyaluronic acid synthase 2 (Has2) in cranial neural crest cell lineages. All Has2 conditional knockout (cko) mice had cleft palate due to failed shelf elevation during palate development. The HA content was significantly reduced in the craniofacial mesenchyme of Has2 cko mutants. Reduced HA content affected the ECM space and shelf expansion to result in a reduced shelf area and an increased mesenchymal cell density in the palatal shelves of Has2 cko mutants. We examined palatal shelf movement by removal of the tongue and mandible from unfixed E13.5 and early E14.5 embryonic heads. Reduced shelf expansion in Has2 cko mutants altered palatal shelf movement in the medial direction resulting in a larger gap between the palatal shelves than that of littermate controls. We further examined palatal shelf movement in the intact oral cavity by culturing explants containing the maxilla, palate, mandible and tongue (MPMT explants). The palatal shelves elevated alongside morphological changes in the tongue after 24-h culture in MPMT explants of early E14.5 wild type embryos. On the contrary, shelf elevation failed to occur in MPMT explants of age-matched Has2 cko mutants because the tongue obstructs palatal shelf movement, suggesting that reduced shelf expansion could be essential for the palatal shelves to interact with the tongue and overcome tongue obstruction during shelf elevation. Has2 cko mutants also showed micrognathia due to reduced HA content in the mandibular mesenchyme including Meckel's cartilage. Through 3D imaging and morphometric analysis, we demonstrate that mandibular growth results in a significant increase in the vertical dimension of the common oral-nasal cavity that facilitates palatal shelf movement and its interaction with the tongue during shelf elevation. • Reduced mesenchymal HA content results in cleft palate and micrognathia. • The HA accumulation promotes palatal shelf expansion and movement. • Palatal shelf elevation relies on the palatal shelf-tongue interaction. • Mandibular growth regulates the vertical dimension of the common oral-nasal cavity. [ABSTRACT FROM AUTHOR]

We introduce in this article a global philosophy in the approach to diagnosis and treatment in growing orthodontics that can be add or remove elements over time, but that aims again to inspire and thrill the orthodontist and offer a thought guide with more ambitious goals. Only time, together with a strict reassessment of long-term results, will guide us on the way. We describe the objectives, two pillars and four keys in which we base the interceptive treatment on. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study was to assess craniofacial growth pattern in children with generalized decreased skeletal age and compare it with the children having normal skeletal age. Materials and methods: Lateral cephalograms and hand wrist radiographs of 40 patients (age group 3–14 years) were taken and skeletal age assessment was done with hand wrist radiographs according to Greulich and Pyle, based on which two groups were made, Group A – Control group (normal skeletal age) and Group B – study group (decreased skeletal age). Group A had a sample size of 21 and Group B, a sample size of 19. These were further divided into subgroups according to age: subgroup (a) – 3 to 6 years, subgroup (b) – 7 to 11 years and subgroup (c) – 12 to 14 years. The skeletal and dental patterns were analyzed with Down's Cephalometric analysis. Student “t” test was used to verify comparisons in all the subgroups of patients of Group A and Group B. Results: The facial angle and Cant of occlusal plane exhibited maximum difference between the two groups which indicated that mandibular growth was affected more than other bones in diseased child patients. Conclusion: The present study led to the conclusion that craniofacial growth was retarded in children with generalized decreased skeletal age in comparison to healthy child patients.

Objectives: The purpose of the present study was to investigate the relationship of the measured distance between two mandibular points (distance M-Me) to chronological age and to find out whether the absolute values of distance M-Me could be classified age-wise into a unique range, which could be directly read for predicting the stage of mandibular growth. Methods and Materials: The study sample consists of lateral cephalometric records of 65 patients (34 females and 31 males; age range: 6–21 years). Chronological age was calculated in decimal years. Lateral cephalograms were assessed by two independent examiners. Points M and Me were located on the lateral cephalograms, and linear distance between them was measured. Results: Pearson product-moment correlation coefficients showed a high correlation between chronological age and distance M-Me (0.746 for females and 0.869 for males, p < 0.01). When the values of distance M-Me were compared with chronological age, it was possible to make four age groups (for females and males separately), where each group showed a unique range of value for distance M-Me. The values increased with increasing age. Conclusions: Increase in value of distance M-Me with age, showing reduced individual variation, depicts a well-conserved linear dimension. Values of distance M-Me can be directly read for predicting the stage of mandibular growth and can be used as a valuable adjunct or substitute to chronological age.

Purpose: Bisphosphonates are commonly used drugs in pediatric patients in the treatment of osteoporotic diseases and various types of cancers. The purpose of this study was to evaluate the effects of pamidronate administration on mandibular growth and tooth eruption in new born rats. Materials and Methods: Forty Sprague Dawley rats were included in the study and divided into four groups as; 14th day pamidronate group, 30th day pamidronate group, 14th day control group and 30th day control group. Pamidronate groups were daily injected with 1.25 μg/g pamidronate disodium subcutaneously whereas control groups were injected with sterile saline. Eruption levels of lower incisor and molar teeth were assessed macroscopically. Mandibular growth was assessed by measuring reference points in cone beam tomography. Histological and histomorphometric examinations were performed under light microscope to evaluate tooth morphology and number of osteoclasts. Results: Retardation in mandibular growth, decrease in number of osteoclasts, delay in tooth eruption, degeneration in both tooth morphology and structure were observed in the pamidronate groups compared to control groups. Conclusion: Pamidronate administration during growth and development stage may adversely affect tooth eruption and mandibular growth in new born rats.

Introduction: This study aimed to discover the genetic and environmental factors that contribute to the mandibular development of untreated monozygotic and dizygotic twins., Material and Methods: The sample, taken from the Forsyth Moorrees Twin Study, included 52 untreated monozygotic twins (36 male, 16 female) and 46 untreated dizygotic twins (23 male, 23 female). At the ages of 12 and 17, lateral cephalograms were collected and traced to assess total mandibular length, mandibular ramus length, mandibular corpus length, gonial angle, SNB, and bony chin prominence. The genetic and environmental components of variation were assessed using multilevel mixed-effects structural equation modelling., Results: At 12 years of age, high additive genetic influences were observed for total mandibular length (74%), gonial angle (76%), SNB (41%), and bony chin prominence (64%), whereas strong dominant genetic components were observed for corpus length (72%), and mandibular ramus length was under unique environment influence (54%). At 17 years of age, only total mandibular length (45%), ramus length (53%), gonial angle (76%), and bony chin prominence (68%) were under strong additive genetic control, while the remainder were under strong dominant genetic control., Conclusions: Although monozygotic and dizygotic twins share at least a portion of their DNA, additive, dominant, or environmental components were discovered during adolescence. Nonetheless, by the age of 17, the majority of the mandibular traits are under either additive or dominant genetic impact., (Copyright © 2023 The Author(s). Published by Elsevier Masson SAS.. All rights reserved.)

Knowledge of timing and duration of the adolescent growth spurt is essential to treat skeletal jaw discrepancies in the growing child. The purpose of this review of literature was to evaluate the validity and reliability of the maturational stages of the cervical vertebrae C2, C3 & C4 as seen on lateral cephalograms in the prediction of peak pubertal growth spurt. Literature review purported that cervical vertebral maturity indicators were effective in assessing the circumpubertal growth spurt. The drawbacks of this method of assessment was that it evaluated the skeletal maturity at one point of time and that it failed to pinpoint the peak in mandibular growth. It also did not specify the intensity and amount of residual growth left, factors deemed important for implementing orthopedic therapy. [ABSTRACT FROM AUTHOR]

The long-standing debate around the origin and evolutionary mode of the Neandertal lineage is connected to the understanding of the large morphological diversity found in the European Middle Pleistocene Hominin (EMPH) samples. In practical terms, this problem can be approached through two questions: How many morphs can be distinguished in EMPH and how do they relate to the origin of Neandertals? These questions are addressed in this paper by means of geometric morphometric comparative analyses in combination with principles of craniofacial biology. We use the mandible as a model system because of its relative abundance in the fossil record, the presence of diagnostic features relevant to the process under analysis, and the key role played by some specimens. Among them, three samples are central in the debate: the Mauer mandible (as the holotype of Homo heidelbergensis), and the Arago and Atapuerca-SH samples. Our comparative analyses conclude that the Mauer and Arago samples derived from a single deme, and that Neandertal derived features that represent an incipient phase of the evolutionary process. The specimen AT-950 from the Atapuerca-SH sample has a number of structural similarities with Mauer, Arago and Montmaurin, which allows linking of this latter group with the complete Atapuerca-SH hypodigm. Consequently, all of these specimens are considered members of the Neandertal lineage. The fossil record illustrates a long evolutionary Neandertal lineage going back at least 0.6 million years. Against populational-based interpretations, we favor a structuralist approach and follow Enlow's counterpart growth analysis and compensatory growth mechanisms for interpretation of the EMPH diversity. In this framework, morphometric cranio-mandibular variation in hominin samples from the European Middle Pleistonece must be contemplated within the head form vertical variation pattern (e.g. vertical dolicho- and brachyfacial form spectrum) widespread in Hominoid species. • A morphogenetic structuralist perspective is provided. • A two species model is supported for a long evolutionary Neandertal lineage. • European Middle Pleistocene hominin samples are classified as Homo heidelbergensis. • Arago II, Mauer and AT-950 mandibles share a form pattern. • A plesiomorphic facial variation pattern explains European Middle Pleistocene forms. [ABSTRACT FROM AUTHOR]

Objective: The concept of mandibular catch-up growth is often quoted in the literature regarding Pierre Robin sequence (PRS). We endeavored to perform a systematic review of whether the literature supports this concept. Design: Systematic review. Interventions: A PubMed-based systematic review of the English literature was performed of articles objectively measuring mandibular growth or position after nonoperative management of PRS. Main Outcome Measures: Rate and end point of mandibular length, ramus length, gonial angle, and maxillomandibular discrepancy. Results: The initial search delivered 607 English-language abstracts. Of these, 16 met inclusion criteria. Eight articles evaluating 143 patients followed longitudinal patient data and therefore allowed comparison of growth rates to controls. Ten articles evaluating 228 patients presented cross-sectional data and therefore could only evaluate a single time point. Two of the 8 longitudinal studies reported faster than normal growth of mandibular length in a significant portion of their cohort. Five of 8 reported equal growth rates. One of 16 studies reported that mandibular length of patients with PRS normalized compared to controls. Two of 16 studies reported no difference in maxillomandibular discrepancy between PRS and controls, whereas 10 reported a posteriorly displaced mandible relative to the maxilla in PRS. Significant differences in control groups, patients, and age existed between studies. Conclusions: While the concept of catch-up growth in PRS is often quoted, a minority of objective studies suggest increased mandibular growth rates in isolated PRS. Even fewer studies suggest that the maxillomandibular discrepancy in PRS completely resolves. [ABSTRACT FROM AUTHOR]

Highlights • Different effects between resecting articular disc and condylar cartilage on mandibular growth were compared for the first time. • Either disc or cartilage resection would interfere increase of mandibular height. • Height deficiency occurred earlier and more severely when condylar cartilage was resected. • Either disc or cartilage resection barely interfered increase of mandibular length. Abstract Objective This study was aimed to compare the effects of articular disc and condylar cartilage resection on mandibular growth in Sprague Dawley rats. Design Eighty-four male Sprague Dawley rats (age = 4 weeks) were grouped according to the following procedures: group A (n = 21), exclusive surgical exposure of articular disc and condylar cartilage; group B (n = 21), exclusive surgical resection of articular disc; group C (n = 21), exclusive surgical resection of condylar cartilage; group D (n = 21), surgical resection of both articular disc and condylar cartilage. All surgery was performed in unilateral. One rat was killed in each group immediately after the surgery. Hematoxylin and eosin (H&E) staining was used to confirm the completely removal of the disc or cartilage. Five rats in the four groups were sacrificed in 1, 3, 6, and 9 weeks post-operation. The heights and lengths of the mandibles were measured and analyzed statistically. Results The mandibular height of group D (5.01 ± 0.25 mm) was statistically lower than group A (5.59 ± 0.17 mm) at 1 week post-operation. The height of group C (5.62 ± 0.26 mm) was significantly lower than group A (6.27 ± 0.31 mm) 3 weeks after surgery. The height of group B (6.38 ± 0.36 mm) was significantly lower than group A (6.95 ± 0.10 mm) 6 weeks after surgery. At 9 weeks post-operation, the mandibular heights in groups B, C, and D were lower than group A, group D was lower than group C, and group C was lower than group B. The lengths of the mandibles were not significantly decreased until 9 weeks post-operation in group D. Conclusions The increase in mandibular height was interfered after either articular disc or condylar cartilage was resected, and mandibular height deficiency likely occurred earlier and more severely when cartilage was resected. However, the increase in mandibular length was barely interfered when either articular disc or condylar cartilage was resected. [ABSTRACT FROM AUTHOR]

The dynamic relation of the anteroposterior and rotational growth of the mandible to the transverse arch width and dental height changes must be understood before placing endosseous implants in actively growing patients. Research models demonstrate that osseointegrated implants lack the compensatory growth mechanism of the natural dentition. Remodeling associated with skeletal growth in the region of the implant placement site could cause the implant to either become unsupported by bone or submerged within it. Implants placed after age 15 in girls and 18 in boys have the most predictable prognosis. When placed in the growing patient, dental implants should be closely monitored and carefully restored with implant prostheses designed to accommodate growth and development. [ABSTRACT FROM AUTHOR]

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.