Mandibular Retrognathism Research Articles

Biomechanical effects of functional clear aligners on the stomatognathic system in teens with class II malocclusion: a new model through finite element analysis

ObjectivesThe Functional Clear Aligner (FCA) is a novel orthodontic appliance designed for the treatment of Class II malocclusion with mandibular retrognathia in adolescents. The aim of this study was to investigate the biomechanical characteristics of the masticatory muscles, jawbone, and temporomandibular joint (TMJ) during mandibular advancement using either FCA or Class II elastics combined with clear aligner (Class II elastics) through finite element analysis.Materials and methodsA 3D finite element model of the ‘muscle-jawbone-TMJ-appliance’ system was constructed based on CBCT and MRI images of a boy with skeletal Class II malocclusion. Masticatory muscles included masseter, temporal, medial pterygoid, and lateral pterygoid muscles. The TMJ consists of the temporal bone’s glenoid fossa, disc, and mandibular condyle. To observe the biomechanical characteristics of the muscles and TMJ during orthodontic appliance wearing and the retention phase, two different protocols were used: Model 1: The mandibular advancement using FCA; Model 2: The mandibular advancement using Class II elastics.ResultsThe FCA group produced greater and more coordinated masticatory muscle forces compared to the Class II elastics group. Temporal and masseter muscles exhibited the most pronounced variation in muscle strength during mandibular advancement. The FCA group exhibited greater TMJ region stress compared to the Class II elastics group. Interestingly, the stress on the articular discs in both models decreased over time. Tensile stresses were observed in both the condyle and the posterior region of the articular fossa.ConclusionDuring skeletal Class II malocclusion treatment, masticatory muscle forces and stress on the TMJ were higher in the FCA group compared to the Class II elastics group. In both models, stress cushioning was provided by the articular disc.

Effect of exercise versus mandibular advancement device in moderate obstructive sleep apnea patients with mandibular retrognathia: A randomized clinical trial

ABSTRACT Objective The aim of this study was to investigate the effects of exercise and mandibular advancement device (MAD) on severity of Obstructive sleep apnea syndrome (OSAS) with mandibular retrognathia. Methods Patients were randomly allocated into either exercise group or MAD group. All patients underwent blood tests, polysomnography studies and questionnaires studies at enrollment and at the 12-week’s follow-up. Results Our study showed MAD was superior to exercise in improving polysomnographic outcomes and Snore Scale (SS) score. No significant difference was observed between the two treatments in terms of Epworth Sleepiness Scale (ESS) score. Moreover, in the exercise group, improvements were also observed in total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C). Conclusion MAD was more effective than exercise in improving sleep efficiency. Exercise can improve daytime sleepiness and lipid metabolism, independent of the effects on BMI. Trial registration ChiCTR2000034188

Postoperative maxillary stability after Le Fort I osteotomy using a u-HA/PLLA system: three-dimensional analysis by surface superimposition based on virtual Le Fort I osteotomy

The postoperative stability achieved with Le Fort I osteotomy (LFI) using bioabsorbable systems remains controversial. A new method – multipoint measurement method – was devised for detailed three-dimensional examination of postoperative stability following LFI, and the stability after LFI when using SuperFIXSORB-MX made of u-HA/PLLA was investigated. Thirty-one patients who underwent LFI using SuperFIXSORB-MX were evaluated retrospectively. The patients were divided into four malocclusion types: open bite, mandibular retrognathia, mandibular protrusion, and facial asymmetry. Seven maxillary reference points were measured three-dimensionally using computed tomography scans obtained preoperatively (T0), 4 days post-surgery (T1), and 1 year post-surgery (T2). Surgical changes (T1–T0) and the postoperative discrepancy (T2–T1) of the maxilla were analysed to evaluate postoperative stability by surface superimposition of the virtual LFI segments. Postoperative discrepancy was the largest for the facial asymmetry type, ranging from 0.75 ± 0.45 mm to 0.98 ± 0.52 mm in three-dimensional distance (minimum to maximum mean ± standard deviation values for the individual reference points). The relapse at U1 was 16% in the transverse axis, and the anterior nasal spine moved further upward by 17% of the amount of movement of the maxilla. Fixation with SuperFIXSORB-MX was considered to be within clinically acceptable limits.

New Solution in the Treatment of Children with Class II Malocclusion: Biblock Appliance.

A new design, the Biblock appliance, was developed for the functional treatment of Class II malocclusions. To compare the effects of Biblock appliance (BA) and Activator appliance (AA) on the skeleton, dentoalveolar, and soft tissue in Class II malocclusions. Thirty-five patients with mandibular retrognathia caused by skeletal Class II malocclusion and normodivergent growth pattern were included in this study. After selecting the BA group (n = 17, 8 boys and 9 girls, mean age = 12.08 ± 0.37 years), we selected the active control group treated with AA (n = 18, 9 boys and 9 girls, mean age = 12.3 ± 0.27 years), which matched the BA group's development and gender. All patients were between PP2 = DP3u periods according to hand-wrist maturation. Cephalometric variables related to the skeletal, dentoalveolar, and soft tissue were measured. Treatment duration was 18.17 ± 1.45 months with BA and 16.92 ± 1.09 months with AA. Skeletal Class II malocclusion improved significantly in both groups. In the compared groups, the increase in ANS-Me was significantly higher in the AA group (P < 0.05). The Cd⊥SN and S-Cd increase in the compared groups was significantly higher in the BA group (P < 0.05). There was no significant difference in measurements between the groups in skeletal, dentoalveolar, and soft tissue measurements (P > 0.05). The effects of AA, an appliance accepted by the orthodontic community, and BA, a new design, on the skeletal, dentoalveolar, and soft tissue were similar.

TREATMENT OF PATIENTS WITH PIERRE ROBIN SYNDROME THROUGH OSTEOGENIC DISTRACTION SURGERY

The Pierre Robin sequence is defined as a congenital anomaly characterized by the presence of glossoptosis, micrognathia, and airway obstruction, leading to various complications. Mandibular distraction osteogenesis (MDO) emerges as a surgical treatment option that has been yielding positive results for individuals with Pierre Robin sequence (PRS), directly addressing craniofacial correction, aiming for improved respiratory quality, and enabling adequate mandibular elongation. This study aims to evaluate mandibular distraction osteogenesis and its efficacy in patients with PRS. The literature search encompassed PubMed, Medical Literature Analysis and Retrieval System Online, Latin American and Caribbean Health Sciences Literature, and the Scientific Electronic Library Online, using the DeCS descriptors: "Pierre Robin Syndrome" AND "Distraction Osteogenesis" AND "Micrognathism". Studies have demonstrated the efficacy of MDO as a therapeutic approach to correcting respiratory and feeding problems, with the FEMOD protocol showing promise in improving upper airways and correcting micrognathia. Although studies point to MDO as a good solution for treating mandibular retrognathia in PRS patients, further research is still needed to validate results, compare different treatment approaches, assess long-term surgery effects, and identify potential late complications. This underscores the importance of a multidisciplinary approach to treating these patients.

Current Status of the Management of Idiopathic Condylar Resorption/Progressive Condylar Resorption-A Scoping Review.

The temporomandibular joint (TMJ) is a complex synovial joint shrouded in mystery, as the etiology of many TMJ disorders are unsolved. Idiopathic/progressive condylar resorption (ICR/PCR) is one such TMJ disorder characterized by a gradually deteriorating mandibular condylar mass, resulting in severe mandibular retrognathia, which often accompanied by clockwise rotation of mandible and an anterior open bite. Since the etiology of the ICR/PCR remains unclear, no definitive prevention or management options have been established. To date, various symptomatic non-surgical, surgical, and salvage management options have been developed and reported. To understand the current status of the ICR/PCR management options, this article provides an overview of the options presently reported in the literature to reduce its TMJ symptoms and improve mandibular function and form.

Prevalence of sleep-disordered breathing in children and adolescents with large horizontal maxillary overjet due to mandibular retrognathia: a case control study.

The aim of the study was to examine the prevalence of sleep-disordered breathing (SDB) in children and adolescents with large overjet due to mandibular retrognathia compared to a control group. In this case-control study children with large overjet ≥ 6 mm due to mandibular retrognathia (study group) were compared to a group with neutral occlusion (controls). All participants underwent respiratory polygraphy (PG) and questionnaires regarding sleepiness and snoring. Differences across groups were tested by: Chi-square, general linear model adjusted for age, sex, and body mass index (BMI), and Mann-Whitney test. Differences in results of PG were also tested by general linear model adjusted for age, sex, and BMI according to severity of mandibular retrognathia. Thirty-seven (19 male;18 female, median age 12.3 years) participants were included in the study group and 32 (16 male;16 female, median age 12.2 years) in the control group. No significant difference in SDB assessed by PG or questionnaires between the groups was found even though the snore index was higher in the study group (p=0.051). The snore index was higher than the parent-reported snoring. Respiration rate was significantly reduced in the study group (p=0.043), and estimated sleep time efficiency was significantly reduced in males compared to females (p<0.001). No significant differences in SDB were found between the groups even though the snore index was higher in the study group. The snore index of the PG was higher than the parent-reported snoring. Estimated sleep time efficiency was reduced in males. The study improves the understanding of risk of SDB in non-obese children with large overjet due to mandibular retrognathia and may contribute to an interdisciplinary approach of risk assessment of SDB in children with malocclusion. NCT04964830.

Evaluation of the Changes in Condylion-Gonion-Menton Angle and Dentoalveolar Heights After Treatment of Skeletal Class II Division I Malocclusions with Removable Functional Appliances

Objectives: Condylion-Gonion-Menton (CoGoMe) angle and dentoalveolar heights are important parameters that provide information about maxillomandibular growth and development. This study aimed to examine the changes in the CoGoMe angle and dentoalveolar heights after functional treatment and to analyze whether they are related to each other. Materials and Methods: A total of 60 patients, 38 females (mean age 11.7 ± 0.6) and 22 males (mean age 12.6 ± 0.5), with skeletal class II division I malocclusion caused by mandibular retrognathia in the peak period were included. Linear measurements of skeletal angular and dentoalveolar heights were made on lateral cephalograms taken pre- (T0) and post-functional treatment (T1). Paired sample t test, Wilcoxon test and Spearman’s rho correlation coefficient were used for statistical analyses. Statistical significance was accepted as p

Prevalence of obstructive sleep apnea and its associated factors in primary health care in Morocco.

Obstructive sleep apnea is a common respiratory disorder that is still underdiagnosed in Morocco. This study aims to determine the prevalence of obstructive sleep apnea and its associated factors in primary healthcare. In this cross-sectional study, 815 adults aged 18 years and older consulting in the primary health care services in Marrakech, Morocco, were included. We evaluated the risk of obstructive sleep apnea syndrome using the modified STOP-BANG questionnaire. The prevalence of the high risk of obstructive sleep apnea in our sample is 24.8% (CI 95%: 21.7 - 27.6%). The variables independently associated with the high suspicion of obstructive sleep apnea were: gender male (p = 0.001), age ≥ 45 years (p = 0.001), high blood pressure (p = 0.005), hyperlipidemia (p = 0.042), daytime sleepiness (p = 0.003), snoring (p = 0.001), tiredness (p = 0.001) and mandibular retrognathia (p = 0.025). This survey revealed a significant prevalence of obstructive sleep apnea in Morocco. Therefore, we propose to generalize the screening of obstructive sleep apnea in hypertensive patients who report symptoms including daytime sleepiness, snoring, nocturnal choking, and tiredness that are unexplained by other known factors.

Evaluation of hard palate and cleft morphology in neonates with Pierre Robin Sequence and Cleft Palate Only.

This study aimed to establish a fully digital measurement protocol for standardizing the description of hard palate and cleft morphology in neonates with an isolated cleft palate (CPO) and Pierre Robin sequence (PRS). A total of 20 digitized plaster models of neonates with CPO and 20 digitized plaster models of neonates with PRS were retrospectively investigated. For the control group, the hard palate was segmented from 21 pre-existing 1.5 T MRI datasets of neonates and exported as an STL file. The digital models were marked with predefined reference points by three raters. Distance, angular, and area measurements were performed using Blender and MeshLab. Neonates with CPO (20.20 ± 2.33 mm) and PRS (21.41 ± 1.81 mm) had a significantly shorter hard palate than the control group (23.44 ± 2.24 mm) (CPO vs. control: P < .001; PRS vs. control: P = .014). Notably, neonates with PRS (33.05 ± 1.95 mm) demonstrated a significantly wider intertuberosity distance than those with CPO (30.52 ± 2.28 mm) (P = .012). Furthermore, there were also significant differences measured between the cleft and control groups (25.22 ± 2.50 mm) (P < .001). The data from this study demonstrate the feasibility of using MRI datasets to generate digital models of the hard palate. The presence of a cleft palate leads to pronounced adaptations of the total palatal surface area, dorsal width, and length of the hard palate. Mandibular retrognathia and altered tongue position in PRS, as opposed to CPO, might further impact palatal morphology and intertuberosity distance.

Transforming Adolescent Smiles: Correcting Skeletal Mandibular Retrusion and Bimaxillary Protrusion with Clear Aligners.

Maxillary protrusion combined with mandibular retraction is a highly prevalent but extremely complex maxillofacial deformity that can have a serious negative impact on patients' facial aesthetics and mental health. The traditional orthodontic treatment strategy often involves extracting 4 first premolars and conventional fixed techniques, combined with mini-implant screws, to retract the anterior teeth and improve facial protrusion. In recent years, an invisible orthodontic technique, without brackets, has become increasingly popular. However, while an invisible aligner has been used in some cases with reasonable results, there remain significant challenges in achieving a perfect outcome. This case report presents an adolescent patient with bimaxillary protrusion and mandibular retrognathia. Based on the characteristics of the invisible aligners and the growth characteristics of the adolescent's teeth and jawbone, we designed precise three-dimensional tooth movement and corresponding resistance/over-correction for each tooth, while utilizing the patient's jawbone growth potential to promote rapid development of the mandible, accurately and efficiently correcting bimaxillary protrusion and skeletal mandibular retrognathia. The patient's facial aesthetics, especially the lateral morphology, have been greatly improved, and various aesthetic indicators have also shown significant changes, and to the patient's great benefit, invasive mini-implant screws were not used during the treatment. This case highlights the advantages of using invisible aligners in adolescent maxillary protrusion combined with mandibular retraction patients. Furthermore, comprehensive and accurate design combined with good application of growth potential can also enable invisible orthodontic technology to achieve perfect treatment effects in tooth extractions, providing clinical guidance for orthodontists.

Non - extraction treatment of class ii division 2 malocclusion with forsus fatigue-resistant device – 2 case report

Class II malocclusion is one of the most frequent problems encountered in orthodontic. The most common characteristic of Class II malocclusion is mandibular retrognathia rather than maxillary protrusion according to McNamara. Non-growing patients with Class II mandibular retrusion are mostly treated with fixed functional appliances. This article represents two case reports of Class II division 2 malocclusion cases treated with Forsus Fatigue Resistant Appliance after initial levelling and alignment. Forsus Fatigue Resistant appliance in particular when used in conjunction with full bonded fixed appliance facilitate the correction of Class II Div 2 malocclusion by skeletal and dental changes.

Functional therapy and adenotonsillectomy clinical trial for class II malocclusion (FACT-II): protocol for a randomised controlled trial

IntroductionClass II malocclusion with mandibular retrognathia is a common complication of paediatric obstructive sleep apnoea (OSA), often accompanied by transverse maxillary deficiency. In early orthodontic treatment, a twin block (TB)...

ORTHODONTIC MANAGEMENT OF THALASSEMIA INTERMEDIA – A CASE REPORT

Background: Beta Thalasssemia (βT) is a genetic disorder causing various orofacial manifestations. It presents clinically in the form of maxillary prognathism and mandibular retrognathism with steep mandibular plane angles. Case Description: This case report presents 9.5 yrs male patient with β Thalasssemia and clinically a developing Class II malocclusion with vertical maxillary excess causing a gummy and unpleasant smile. Orthodontic treatment aimed at restricting the growth of maxilla with use of headgear followed by correcting the dental malocclusion with the help of fixed orthodontic. 3M forsus resistance device was given for mandibular advancement and Class II correction. Conclusions: Early intervention, proper diagnosis and ideal treatment strategy of the case helped achieving good occlusion for the patient and controlled the Class II growing tendency typically seen in thalassemia patients if not addressed at an early age.

ORTHODONTIC MANAGEMENT OF THALASSEMIA INTERMEDIA – A CASE REPORT

clinically in the form of maxillary prognathism and mandibular retrognathism with steep mandibular plane angles. Case Description: This case report presents 9.5 yrs male patient with β Thalasssemia and clinically a developing Class II malocclusion with vertical maxillary excess causing a gummy and unpleasant smile. Orthodontic treatment aimed at restricting the growth of maxilla with use of headgear followed by correcting the dental malocclusion with the help of fixed orthodontic. 3M forsus resistance device was given for mandibular advancement and Class II correction Conclusions: Early intervention, proper diagnosis and ideal treatment strategy of the case helped achieving good occlusion for the patient and controlled the Class II growing tendency typically seen in thalassemia patients if not addressed at an early age.

Mandibular Endochondral Growth Is Specifically Augmented by Nutritional Supplementation with Myo-Inositol Even in Rabbits.

Mandibular retrognathism occurs by insufficient mandibular growth and causes several issues, such as respiratory difficulty and diminished masticatory function. At present, functional orthodontic appliances are used for stimulating mandibular growth in pediatric cases. However, the effectiveness of functional appliances is not always stable in daily practices. A more effective, reliable, and safer therapeutic method for mandibular growth promotion would be helpful for growing mandibular retrognathism patients. As we previously discovered that nutritional supplementation of myo-inositol in growing mice specifically increases mandibular endochondral growth, we performed preclinical animal experiments in rabbits in this study. Briefly, six-week-old male Japanese white rabbits were fed with or without myo-inositol supplementation in laboratory chow until 25 weeks old, and 3D image analysis using micro CT data and histological examinations was done. Myo-inositol had no systemic effect, such as femur length, though myo-inositol specifically augmented the mandibular growth. Myo-inositol increased the thickness of mandibular condylar cartilage. We discovered that the nutritional supplementation of myo-inositol during the growth period specifically augmented mandibular growth without any systemic influence, even in rabbits. Our results suggest the possibility of clinical use of myo-inositol for augmentation of the mandibular growth in growing mandibular retrognathism patients in the future.

Forced Esthetic Position: A Diagnostic Strategy for Anteroposterior Repositioning in Orthognathic Surgeries.

Considering the esthetic goals involved in orthognathic surgeries, one of the challenges is to define the horizontal projection of the jaws. Most of the cephalometric analyses are focused on the position of the upper incisor and upper lip. Planning the correction of a mandibular retrognathism can be simplified by clinical simulation asking the patient to project their mandible. A forced esthetic position protocol is presented as a starting point for the planning in orthognathic cases.

Role of the Growth Hormone Receptor (GHR) Gene in Skeletal Class II Malocclusion and Its Significant Influence on the Skeletal Facial Profile in Both the Sagittal and Vertical Dimensions: A Systematic Review.

This systematic review aims to determine the role of the growth hormone receptor (GHR) gene in skeletal malocclusion and its significant influence on the growth of the maxilla and the mandible in both sagittal and vertical dimensions. A search of the electronic databases of PubMed, Google Scholar, and Cochrane up to and including the year 2023 was made. In addition to this, a hand search of orthodontic and dentofacial orthopaedic journals was carried out. This search included randomized control trials. The Mesh terms used were "skeletal class II malocclusion", "mandibular retrognathism", "sagittal malocclusion", "genetic expression", "genetic factors", "genetic study", "genetic polymorphism", and "single nucleotide polymorphism". The inclusion criteria included studies such as clinical trials and orthopaedic appliances in the presurgical phase. The exclusion criteria for the study were studies not in the English language, case reports, case series, and studies with irrelevant data. It has been cited in various literature that polymorphic variations of the GHR gene could cause variations in mandibular morphogenesis affecting both the mandibular body length and ramal height. However, its effects are quite variable and are based on different population groups. Polymorphism of the GHR gene can be considered a reliable indicator predicting variations in affecting the growth of the mandible with greater significance in affecting the vertical ramal height compared to the body length of the mandible. Its effects on the maxillary skeletal base are rather limited comparatively.

New insights into the genetics of mandibular retrognathism: novel candidate genes.

Mandibular retrognathism (MR) is acommon skeletal malocclusion in humans with astrong genetic component. Single nucleotide polymorphisms (SNPs) in genes encoding epidermal growth factor (EGF) and EGF receptor (EGFR) could be involved in the etiology of mandibular retrognathism. Therefore, in this study, we investigated whether SNPs in the genes encoding for EGF and EGFR are associated with MR in German teenagers. This nested case-control study evaluated German orthodontic patients, aged 10-18years. DNA, which was isolated from buccal epithelial cells using two cytobrushes, was used for genotyping analysis and digital pretreatment lateral cephalograms were examined to calculate SNB and ANB. Patients with aretrognathic mandible (SNB < 78°) were included as cases, while patients with an orthognathic mandible (SNB = 78-82°) were included as controls. Four SNPs in the genes encoding for EGF and EGFR were chosen and genotyped using real-time PCR. Allele, genotype, and haplotype frequency were compared across groups (α = 5%). Finally, 119 patients were included in this study (45orthognathic mandible, 74retrognathic mandible). The minor alleleG in rs4444903 (EGF) was statistically more frequent in individuals with an orthognathic mandible (p = 0.008). The haplotype formed by the mutant alleles for rs4444903|rs2237051 (EGF; G|A) was statistically more frequent in the orthognathic mandible group (p = 0.007). The SNPs rs4444903 and rs2237051 in EGF, and rs2227983 in EGFR were statistically associated with adecreasing risk of developing aretrognathic mandible according to univariate and multivariate statistical analysis (p < 0.05). SNPs in EGF (rs4444903 and rs2237051) and EGFR (rs2227983) were associated with MR in our German sample and could be genetic biomarkers for early and individualized diagnostic identification of retrognathic mandibular development by means of genetic screening tests.

A finite element study comparing Advansync® and Twin Block in mandibular anterior repositioning.

This study aims to utilize the finite element method (FEM) to compare the dentoalveolar and mandibular effects associated with anterior mandibular repositioning using AdvanSync® (ADV) and Twin Block (TB). A patient with Class II skeletal malocclusion and mandibular retrognathism was selected. A TB appliance was subsequently applied. Computed Tomography (CT) scans were acquired at the beginning of treatment (T1) and 8 months later (T2). Concurrently, a numerical TB model was validated through FEM simulations, which were compared with the T2 results. The ADV appliance was virtually simulated to evaluate stress and deformation on the condyle, symphysis, first lower molar and lower central incisors. Both simulations demonstrated significant mandibular advancement. However, ADV led to less incisor proclination and more molar intrusion compared to TB. ADV exhibited increased stress in the lower molar area, while TB had higher stress in the lower incisor region. Stress and deformations in the condyle and mandibular symphysis were similar in both simulations, with the highest stress observed at the condylar neck and the lowest at the upper pole of the condylar head. Both appliances achieved similar levels of mandibular advancement, with greater proclination of the lower central incisors and more widespread distribution of stress and molar intrusion when using ADV compared to TB.