Craniofacial Morphology Research Articles

Association between craniofacial patterns and third molar agenesis in orthodontic patients.

Third molar agenesis (TMA) is the most common craniofacial anomaly and has been associated with craniofacial patterns in different populations. Therefore, the aim of this retrospective cross-sectional study was to assess apossible association between craniofacial patterns and TMA in German orthodontic patients. Patients undergoing orthodontic treatment with dental records including anamnesis, pretreatment lateral cephalograms and orthopantomograms were evaluated. Cephalometric analyses were conducted digitally and lines, angles and proportions were measured to investigate craniofacial morphology. Skeletal classes were determined by the individualised Wits appraisal and ANB angle. The TMA was identified with the help of orthopantomograms. Patients showing agenesis of at least one third molar were included in the TMA group. Statistical analysis was performed to assess the association between TMA and craniofacial patterns (αof p ≤ 0.05). Atotal of 148patients were included, 40 (27.0%) presented at least one missing tooth (TMA group) and 108 (73.0%) showed full dentition (control group). Skeletal class determined by the individualised Wits appraisal revealed statistical significance between the TMA and control groups (p = 0.022), in which TMA patients were 11times more likely to present with an individualised skeletal classIII (odds ratio 11.3, 95% confidence interval 1.7-139.5). Skeletal cephalometric analysis revealed no statistical differences between TMA and control groups for any further angular, linear and proportional parameters. Third molar agenesis was associated with skeletal classIII determined by the individualised Wits appraisal.

The biomechanics of chewing and suckling in the infant: A potential mechanism for physiologic metopic suture closure.

Craniosynostosis is a condition with neurologic and aesthetic sequelae requiring invasive surgery. Understanding its pathobiology requires familiarity with the processes underlying physiologic suture closure. Animal studies have shown that cyclical strain from chewing and suckling influences the closure of cranial vault sutures, especially the metopic, an important locus of craniosynostosis. However, there are no human data correlating strain patterns during chewing and suckling with the physiologically early closure pattern of the metopic suture. Furthermore, differences in craniofacial morphology make it challenging to directly extrapolate animal findings to humans. Eight finite-element analysis (FEA) models were built from craniofacial computer tomography (CT) scans at varying stages of metopic suture closure, including two with isolated non-syndromic metopic craniosynostosis. Muscle forces acting on the cranium during chewing and suckling were simulated using subject-specific jaw muscle cross-sectional areas. Chewing and suckling induced tension at the metopic and sagittal sutures, and compressed the coronal, lambdoid, and squamous sutures. Relative to other cranial vault sutures, the metopic suture experienced larger magnitudes of axial strain across the suture and a lower magnitude of shear strain. Strain across the metopic suture decreased during suture closure, but other sutures were unaffected. Strain patterns along the metopic suture mirrored the anterior to posterior sequence of closure: strain magnitudes were highest at the glabella and decreased posteriorly, with minima at the nasion and the anterior fontanelle. In models of physiologic suture closure, increased degree of metopic suture closure correlated with higher maximum principal strains across the frontal bone and mid-face, a strain regime not observed in models of severe metopic craniosynostosis. In summary, our work provides human evidence that bone strain patterns from chewing and suckling correlate with the physiologically early closure pattern of the metopic suture, and that deviations from physiologic strain regimes may contribute to clinically observed craniofacial dysmorphism.

Enlarged occipital spur and craniofacial morphology: a cephalometric analysis.

This cross-sectional study aimed to investigate the association between the occipital spur length and craniofacial morphology in individuals with occipital spur (OS). The study included cephalometric images from 451 individuals (196 females, 255 males, age range was 9-84years). The spur length and craniofacial characteristics were evaluated using cephalograms. Based on spur length, subjects were divided into two groups: the OS group (N = 209) and the enlarged occipital spur (EOS) group (N = 242). Descriptive statistics, Independent T-test, Mann-Whitney U test, chi-square test, Kruskal-Wallis test, and age- and sex-based stratified analyses were performed. The level of significance was set at p < 0.05. Males had significantly larger spur length than females. Spur length was shorter in individuals under 18 than the groups over 18. After adjusting for gender and age, ramus height, mandibular body length, effective length of maxilla, effective length of mandible, anterior cranial base length, posterior cranial base length, anterior facial height, posterior facial height, facial height index, and lower anterior facial height had statistically significant differences between OS group and EOS group. Males exhibit greater spur length than females. Patients under 18 had a shorter spur length than adults. Linear craniofacial measurements were found to be greater in subjects with EOS than the individuals with OS. The craniofacial growth and development of an individual might be associated with EOS. The causal relationship between EOS and craniofacial development requires further longitudinal studies.

Craniofacial Cephalometric Morphology in Caucasian Adult Patients with Cleft Palate Only (CPO).

Orofacial clefts are common birth defects that affect the morphology of the skull. Cleft palate only (CPO) has a different etiology than other types of clefts, and craniofacial morphology in CPO differs from that of UCLP and BCLP. The long-term effect of the cleft and its surgery is visible after growth cessation. However, few studies exist describing cephalometric craniofacial morphology in adults with CPO. The aim of the present study was to describe the cephalometric craniofacial morphology of adult patients with CPO compared to healthy patients. The study included analysis of cephalometric lateral headfilms of 28 adults with CPO and 28 healthy subjects. It was found that the angles of SNA, ANB, 1-:NB angle (°) and Wits appraisal were significantly smaller in CPO, whereas NL-NSL (°), 1+:NA angle (°) and 1+:NA (mm) had significantly higher values in CPO compared to the control group. It has been concluded that CPO in adult patients is characterized by a sagittal jaw discrepancy due to maxillary deficiency, with a tendency for compensatory inclination of the upper and lower incisors.

Study on the method of automatically determining maxillary complex landmarks based on non-rigid registration algorithms

Objective: To explore an automatic landmarking method for anatomical landmarks in the three-dimensional (3D) data of the maxillary complex and preliminarily evaluate its reproducibility and accuracy. Methods: From June 2021 to December 2022, spiral CT data of 31 patients with relatively normal craniofacial morphology were selected from those who visited the Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology. The sample included 15 males and 16 females, with the age of (33.3±8.3) years. The maxillary complex was reconstructed in 3D using Mimics software, and the resulting 3D data of the maxillary complex was mesh-refined using Geomagic software. Two attending physicians and one associate chief physician manually landmarked the 31 maxillary complex datasets, determining 24 anatomical landmarks. The average values of the three expert landmarking results were used as the expert-defined landmarks. One case that conformed to the average 3D morphological characteristics of healthy individuals' craniofacial bones was selected as the template data, while the remaining 30 cases were used as target data. The open-source MeshMonk program (a non-rigid registration algorithm) was used to perform an initial alignment of the template and target data based on 4 landmarks (nasion, left and right zygomatic arch prominence, and anterior nasal spine). The template data was then deformed to the shape of the target data using a non-rigid registration algorithm, resulting in the deformed template data. Based on the unchanged index property of homonymous landmarks before and after deformation of the template data, the coordinates of each landmark in the deformed template data were automatically retrieved as the automatic landmarking coordinates of the homonymous landmarks in the target data, thus completing the automatic landmarking process. The automatic landmarking process for the 30 target data was repeated three times. The root-mean-square distance (RMSD) of the dense corresponding point pairs (approximately 25 000 pairs) between the deformed template data and the target data was calculated as the deformation error of the non-rigid registration algorithm, and the intra-class correlation efficient (ICC) of the deformation error in the three repetitions was analyzed. The linear distances between the automatic landmarking results and the expert-defined landmarks for the 24 anatomical landmarks were calculated as the automatic landmarking errors, and the ICC values of the 3D coordinates in the three automatic landmarking repetitions were analyzed. Results: The average three-dimensional deviation (RMSD) between the deformed template data and the corresponding target data for the 30 cases was (0.70±0.09) mm, with an ICC value of 1.00 for the deformation error in the three repetitions of the non-rigid registration algorithm. The average automatic landmarking error for the 24 anatomical landmarks was (1.86±0.30) mm, with the smallest error at the anterior nasal spine (0.65±0.24) mm and the largest error at the left oribital (3.27±2.28) mm. The ICC values for the 3D coordinates in the three automatic landmarking repetitions were all 1.00. Conclusions: This study established an automatic landmarking method for three-dimensional data of the maxillary complex based on a non-rigid registration algorithm. The accuracy and repeatability of this method for landmarking normal maxillary complex 3D data were relatively good.

The role of the dentist and the orthodontist in early diagnosis of Gorlin-Goltz syndrome: a cephalometric and photometric study.

The aim of this study was to analyse the facial characteristics and the craniofacial morphology in GGS patients in order to enable an early diagnosis. Gorlin-Goltz syndrome (GGS) is a autosomic dominant disease, characterised by basal cell carcinoma, palmar/plantar pits, maxillary and mandibular keratocysts and dental abnormalities. Nine out of a sample of 24 GGS patients had complete cephalometric and photographic records at an average age of 8.7 years. Cephalometric and photometric analysis were carried out with standard analyses and compared with healthy patients matched for sex and age. Early diagnosis of GGS based on clinical features could be useful to identify the presence of keratocysts through x-ray examination proceeding with surgical removal at an early stage, limiting space occupying damages.

Commensal Microbiota Effects on Craniofacial Skeletal Growth and Morphology.

Microbes colonize anatomical sites in health to form commensal microbial communities (e.g., commensal gut microbiota, commensal skin microbiota, commensal oral microbiota). Commensal microbiota has indirect effects on host growth and maturation through interactions with the host immune system. The commensal microbiota was recently introduced as a novel regulator of skeletal growth and morphology at noncraniofacial sites. Further, we and others have shown that commensal gut microbes, such as segmented filamentous bacteria (SFB), contribute to noncraniofacial skeletal growth and maturation. However, commensal microbiota effects on craniofacial skeletal growth and morphology are unclear. To determine the commensal microbiota's role in craniofacial skeletal growth and morphology, we performed craniometric and bone mineral density analyses on skulls from 9-week-old female C57BL/6T germ-free (GF) mice (no microbes), excluded-flora (EF) specific-pathogen-free mice (commensal microbiota), and murine-pathogen-free (MPF) specific-pathogen-free mice (commensal microbiota with SFB). Investigations comparing EF and GF mice revealed that commensal microbiota impacted the size and shape of the craniofacial skeleton. EF versus GF mice exhibited an elongated gross skull length. Cranial bone length analyses normalized to skull length showed that EF versus GF mice had enhanced frontal bone length and reduced cranial base length. The shortened cranial base in EF mice was attributed to decreased presphenoid, basisphenoid, and basioccipital bone lengths. Investigations comparing MPF mice and EF mice demonstrated that commensal gut microbes played a role in craniofacial skeletal morphology. Cranial bone length analyses normalized to skull length showed that MPF versus EF mice had reduced frontal bone length and increased cranial base length. The elongated cranial base in MPF mice was due to enhanced presphenoid bone length. This work, which introduces the commensal microbiota as a contributor to craniofacial skeletal growth, underscores that noninvasive interventions in the gut microbiome could potentially be employed to modify craniofacial skeletal morphology. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Factors affecting obstructive sleep apnea severity depending on craniofacial morphological type

AbstractAimAs the craniofacial morphology has major effects on the occurrence of obstructive sleep apnea (OSA) in Asians, factors contributing to the severity of OSA may differ depending on craniofacial characteristics. This study investigated factors affecting OSA severity in patients according to craniofacial morphological type.MethodsStudy participants comprised 227 men examined following a diagnosis of OSA between May 2017 and October 2021. We examined cephalometric X‐rays and results of polysomnography on presentation, and classified the craniofacial morphological type of the participant as “long face type” (Group L) for facial axis (Fx) angle &lt;86° or as “short face type” (Group S) for Fx angle ≥86°. We conducted stepwise binomial logistic regression analysis with apnea‐hypopnea index (AHI) ≥ 15 events/h or AHI &lt; 15 events/h as the dependent variable and age, body mass index (BMI), and the cephalometric parameters SNA, SNB, Fx, PNS‐P, MPT, MP‐H, SPAS, MAS, and IAS as independent variables.ResultsBMI and PNS‐P in Group S and BMI and MP‐H in Group L were identified as independent predictors of AHI ≥ 15 events/h.ConclusionsFactors affecting severity of OSA differ by craniofacial morphological type, with factors of obesity and hyoid bone position for long face‐type patients and obesity and soft palate length for short face‐type patients. Optimal treatment requires consideration of craniofacial morphology and establishment of treatment policies that take causative factors into account.

Automatic landmarking identifies new loci associated with face morphology and implicates Neanderthal introgression in human nasal shape

We report a genome-wide association study of facial features in >6000 Latin Americans based on automatic landmarking of 2D portraits and testing for association with inter-landmark distances. We detected significant associations (P-value <5 × 10−8) at 42 genome regions, nine of which have been previously reported. In follow-up analyses, 26 of the 33 novel regions replicate in East Asians, Europeans, or Africans, and one mouse homologous region influences craniofacial morphology in mice. The novel region in 1q32.3 shows introgression from Neanderthals and we find that the introgressed tract increases nasal height (consistent with the differentiation between Neanderthals and modern humans). Novel regions include candidate genes and genome regulatory elements previously implicated in craniofacial development, and show preferential transcription in cranial neural crest cells. The automated approach used here should simplify the collection of large study samples from across the world, facilitating a cosmopolitan characterization of the genetics of facial features.

Effect of craniofacial morphology on gingival parameters of mandibular incisors.

To investigate the association between the width of keratinized gingiva (WKG), gingival phenotype (GP), and gingival thickness (GT) with craniofacial morphology in sagittal and vertical dimensions. WKG, GP, and GT of mandibular anterior teeth in 177 preorthodontic patients (mean age 18.38 ± 5.16 years) were assessed clinically using a periodontal probe, a Colorvue Biotype Probe, and ultrasound by a single examiner. Patients were grouped into skeletal Class I, II, and III and hyperdivergent, normodivergent, and hypodivergent based on ANB and SN-MP angles. Mandibular incisor inclination (L1-NB) was also measured. Clinical and cephalometric measurements were repeated to assess inter- and intraexaminer reproducibility. A significant association was found between thin GP and skeletal Classes I and III for the left mandibular central incisor (MCI; P = .0183). In skeletal Class III patients, L1-NB angle demonstrated a decreasing trend as phenotype thickness decreased. A significant association was found between thin phenotype and normodivergent and hypodivergent groups for MCIs (left: P = .0009, right: P = .00253). No significant association between WKG or GT and craniofacial morphology was found. Thin GP is associated with skeletal Class I and III for the left MCI. Thin GP is associated with hypodivergent and normodivergent skeletal patterns for the MCIs. There was no association between WKG and GT and craniofacial morphology in both skeletal and vertical dimensions. Dental compensations that exist due to different craniofacial morphology may influence the GP.

The LRP5 high-bone-mass mutation causes alveolar bone accrual with minor craniofacial alteration.

Mutations in low-density lipoprotein receptor-related protein 5 (LRP5) cause various bone diseases. Several mouse models were generated to study the role of LRP5 in bone development. But most of the studies were confined to the appendicular skeleton. The role of LRP5 in the axial skeleton, especially in the craniofacial skeleton, is largely unknown. The aim of this study was to investigate the craniofacial phenotype with the LRP5G171V mutation. To understand how LRP5 affects craniofacial bone properties, we analyzed LRP5 high-bone-mass mutant mice carrying the G171V missense mutation (LRP5HBM ). Quantitative microcomputed tomographic imaging and histomorphometric analyses were used to study craniofacial phenotypes and bone density. Histology, immunohistochemistry, and in vivo fluorochrome labeling were used to study molecular mechanisms. LRP5HBM mice showed overall minor changes in the craniofacial bone development but with increased bone mass in the interradicular alveolar bone, edentulous ridge, palatine bone, and premaxillary suture. Elevated osteocyte density was observed in LRP5HBM mice, along with increased Runx2 expression and unmineralized bone surrounding osteocytes. Meanwhile, LRP5HBM mice exhibited increased osteoprogenitors, but no significant changes were observed in osteoclasts. This led to a high-bone-mass phenotype, and an increased osteocyte density in the alveolar bone and edentulous ridge. LRP5HBM mice display increased bone mass in the alveolar bone with minor changes in the craniofacial morphology. Collectively, these data elucidated the important role of LRP5 in axial bone development and homeostasis and provided clues into the therapeutical potential of LRP5 signaling in treating alveolar bone loss.

3D hyoid and tongue kinematics reveal mechanism of tongue base retraction during swallowing in Didelphis virginiana

In anthropoid primates, tongue base retraction (TBR) is a key event for airway protection and bolus propulsion during swallowing. In macaques, hyoid protraction and elevation during swallowing reduce the oral volume and squeeze the tongue base to retract. This novel hyoid-powered hydraulic TBR mechanism implies that the morphology and position of the hyoid are functionally relevant for TBR performance. However, macaque’s highly derived craniofacial and hyoid morphology precludes inference on the evolutionary history and driving mechanism of TBR across mammal phylogeny at large. Here we use biplanar videoradiography and the XROMM workflow to infer TBR mechanism in Didelphis virginiana through high-resolution 3D hyolingual kinematics. Similar to macaques, Didelphis has an incomplete hyoid cornu, which would enable a large hyoid range of motion that facilitates oral volume reduction. Unlike macaques, Didelphis hyoid has a more posteriorly resting hyoid position. We predict that TBR will occur in Didelphis through a similar hyoid-powered hydraulic mechanism. We find Didelphis deploys TBR during the first opening (O1) phase (liquid) or slow-open phase (solid) of jaw cycle with retraction and elevation of midline posterior tongue markers. Minimal retraction occurs in lateral tongue markers where extrinsic lingual muscles insert. The tongue base and posterior tongue are lengthening, narrowing and increasing in height during TBR, consistent with predictions based on muscular hydrostat model. The tongue base was not isovolumetric during TBR, but the volume change was orders of magnitude smaller than that observed in macaques. Hyoid protraction and elevation occur before and continue throughout TBR, which strongly suggest concurrent reduction of oral volume as well. Our preliminary data suggest the TBR mechanism in opossums may differ in important ways from that utilized by macaques, where opossums could employ a combination of hydrostatic deformation and hydraulic mechanism to drive retraction of tongue base. We provide novel insights into the conservation of TBR across therian mammals and extend our understanding on the form-function relationships between the hyolingual apparatus and swallowing biomechanics. Hinds Fund, University of Chicago This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Analytical review of graphic methods for the study of dental arches in clinical orthodontics

The analysis of textbook and modern literature sources devoted to the graphic construction of human dental arches was carried out in order to select the optimal research methods, taking into account the individual characteristics of the craniofacial morphology. The features of the construction of dental arches according to the Hawley method are presented and the possibilities of using this technique only for some types of dental arches are shown. Information is given on the amendments to the calculations of the radius of the Hawley circle, taking into account the geometric laws of the circle. Attention is paid to the shape of the dental arch of the milky period of the bite and the possibility of using the Schwartz method in children only with optimal occlusive ratios without signs of anomalies of the dentition-jaw system is noted. Amendments to the A. Schwartz method are presented, taking into account the size of the teeth and the size of the diastem component. The method for determining the size of the dental arches by the parameters of diagnostic triangles and the dental pentagon is shown. Methods of graphic construction of predicted forms of arcs with their anomalies, as well as with defects of long length, including complete adentia, are presented. This analysis can be useful to orthopedic dentists and orthodontists when choosing methods of prosthetic and orthodontic treatment.

Automatic sex estimation using deep convolutional neural network based on orthopantomogram images

Sex estimation is very important in forensic applications as part of individual identification. Morphological sex estimation methods predominantly focus on anatomical measurements. Based on the close relationship between sex chromosome genes and facial characterization, craniofacial hard tissues morphology shows sex dimorphism. In order to establish a more labor-saving, rapid, and accurate reference for sex estimation, the study investigated a deep learning network-based artificial intelligence (AI) model using orthopantomograms (OPG) to estimate sex in northern Chinese subjects. In total, 10703 OPG images were divided into training (80%), validation (10%), and test sets (10%). At the same time, different age thresholds were selected to compare the accuracy differences between adults and minors. The accuracy of sex estimation using CNN (convolutional neural network) model was higher for adults (90.97%) compared with minors (82.64%). This work demonstrated that the proposed model trained with a large dataset could be used in automatic morphological sex-related identification with favorable performance and practical significance in forensic science for adults in northern China, while also providing a reference for minors to some extent.

Effects of short-term motor training on accuracy and precision of simple jaw and finger movements after orthodontic treatment and orthognathic surgery: A case-control study.

Orthognathic surgery has been performed with increasing frequency for the treatment of severe malocclusion, yet the postsurgical neuromuscular recovery of patients has been inadequately studied. To investigate the effect of short-term and simple jaw motor training on accuracy and precision of jaw motor control in patients following orthodontic treatment and orthognathic surgery. Twenty patients who had completed preoperative orthodontics, 20 patients who had undergone bimaxillary orthognathic surgery and 20 age-and-gender-matched healthy controls participated in the study. Participants were asked to perform 10 continuous jaw opening and finger lifting movements before and after a 30-min motor training session. The variability in the amplitude of these simple movements was expressed as percentage in relation to the target position (accuracy - Daccu ) and as coefficient of variation (precision - CVprec ) to describe the motor performance. Furthermore, the changes in amplitude before and after training were measured in percentage. Daccu and CVprec of simple jaw and finger movements significantly decreased after motor training (p ≤ .018) in all groups. The relative changes in finger movements were higher than jaw movements (p < .001) but with no differences among the groups (p ≥ .247). Both accuracy and precision of simple jaw and finger movements improved after short-term motor training in all three groups, demonstrating the inherent potential for optimization of novel motor tasks. Finger movements improved more than jaw movements but with no differences between groups, suggesting that changes in occlusion and craniofacial morphology are not associated with impaired neuroplasticity or physiological adaptability of jaw motor function.

Chicken HOXC8 and HOXC10 genes may play a role in the altered skull morphology associated with the Crest phenotype.

One of the most intriguing traits found in domestic chickens is the Crest phenotype. This trait, characterized by a tuft of elongated feathers sprouted from the head, is found in breeds such as Polish chickens and Silkie chickens. Moreover, some crested chicken breeds also exhibit a protuberance in their anterodorsal skull region. Previous studies have strived to identify the causative factors of this trait. This study aimed to elucidate the role of chicken HOXC8 and HOXC10 in the formation of the Crest phenotype. We explored the effect of ectopic expression of HOXC8 or HOXC10 on the chicken craniofacial morphology using the RCAS retrovirus transformation system. Microcomputed tomography scanning was conducted to measure the 3D structure of the cranial bone of transgenic embryos for geometric morphometric analysis. We found that the ectopic expression of HOXC8 or HOXC10 in chicken heads caused mild morphological changes in the skull compared with the GFP-transgenic control group. Geometric morphometric analysis showed that HOXC8 and HOXC10 transgenic groups expressed a mild upward shape change in the frontal region of the skull compared with the control group, which is similar to what is seen in the crested chicken breeds. In conclusion, this study supports findings in previous studies in which HOX genes play a role in the formation of the altered skull morphology related to the Crest phenotype. It also supports that mutations in HOX genes may contribute to intra- and inter-specific variation in morphological traits in vertebrates.

Age-related hypertrophy of adenoid and tonsil with its relationship with craniofacial morphology

BackgroundWhen analyzing the relationship between adenotonsillar hypertrophy and craniofacial morphology, researchers generally regarded hypertrophied adenoids and tonsils as a whole. It remains unclear whether different enlarged sites of pharyngeal lymphoid tissue would correlate with multiple craniofacial subtypes. We hypothesized there would be craniofacial subtypes correlated with different locations of hypertrophied adenoid and tonsil.MethodsLateral cephalometric radiographs were obtained from 466 children (171 boys and 295 girls, aged 12.27 ± 2.69 years). They were divided into four groups according to different sites of enlarged pharyngeal lymphoid tissue: adenoid hypertrophy group (AG, n = 126), tonsillar hypertrophy group (TG, n = 59), adenotonsillar hypertrophy group (ATG, n = 69) and control group (CG, n = 212). Five commonly used angles for cephalometric measurements were investigated: SNA (Sella-Nasion-Point A), SNB (Sella-Nasion-Point B), ANB (Point A-Nasion-Point B), mandibular plane angle (MP/SN) and Y-axis angle (SGn/FH).ResultsChildren with isolated tonsillar hypertrophy correlated with increased SNA (unstandardized regression coefficient B = 1.38, p = 0.009) and SNB (B = 1.99, p = 0.001) compared with controls. However, children with isolated adenoid hypertrophy correlated with decreased SNB (B=-0.94, p = 0.036), increased ANB (B = 0.74, p = 0.014) and increased MP/SN (B = 2.22, p < 0.001). Similarly, children with adenotonsillar hypertrophy correlated with decreased SNB (B=-1.36, p = 0.015), increased ANB (B = 1.35, p < 0.001) and increased MP/SN (B = 2.64, p = 0.001).ConclusionsIsolated adenoid hypertrophy correlated with a retrognathic mandible, an increased maxillo-mandibular sagittal discrepancy, and an increased mandibular plane angle. Isolated tonsillar hypertrophy correlated with maxillary and mandibular protrusion. Adenotonsillar hypertrophy did not show a superimposed craniofacial pattern of the above two but showed the same craniofacial pattern as isolated adenoid hypertrophy.

Precise modulation of transcription factor levels identifies features underlying dosage sensitivity

Transcriptional regulation exhibits extensive robustness, but human genetics indicates sensitivity to transcription factor (TF) dosage. Reconciling such observations requires quantitative studies of TF dosage effects at trait-relevant ranges, largely lacking so far. TFs play central roles in both normal-range and disease-associated variation in craniofacial morphology; we therefore developed an approach to precisely modulate TF levels in human facial progenitor cells and applied it to SOX9, a TF associated with craniofacial variation and disease (Pierre Robin sequence (PRS)). Most SOX9-dependent regulatory elements (REs) are buffered against small decreases in SOX9 dosage, but REs directly and primarily regulated by SOX9 show heightened sensitivity to SOX9 dosage; these RE responses partially predict gene expression responses. Sensitive REs and genes preferentially affect functional chondrogenesis and PRS-like craniofacial shape variation. We propose that such REs and genes underlie the sensitivity of specific phenotypes to TF dosage, while buffering of other genes leads to robust, nonlinear dosage-to-phenotype relationships.

Treatment Strategy of Mandibular Second Molar Impaction: A Literature Review

Purpose: This literature review aimed to investigate the treatment consideration and strategy of mandibular second molar (MM2) comprehensively, which can be of great assistance on managing and solving such a rare disturbance. Methods: Previous studies were identified in PubMed or Embase database using the keywords “orthodontic,” “molar impaction,” and “uprighting molar.” To enrich the contents of every aspect of the topic, other several related articles were also reviewed and included. Results: Forty-six articles were included and systematically discussed in this review, which were arranged according to prevalence, etiology, diagnosis, treatment strategy, and clinical methods. The incidence of MM2 impaction is 0.06%–0.3% worldwide, and it is related to genetics, craniofacial morphology, space problem, obstacles during eruption, abnormal eruption mechanism, or systemic diseases. Impacted MM2 can be diagnosed by a routine panoramic radiograph according to the definition and criteria. Decision-making depends on patient age, root stage and condition of the impacted tooth, with optimal age of 14 and incompletion root formation. Every treatment option has its indication, benefit/shortcoming, and success rate. Among the four treatment options discussed in this review article, surgical exposure and orthodontic uprighting of the impacted MM2 shows better predictability and success rate, with relatively less side effects. The key biomechanism is to provide the distalizing and uprighting force to rotate the MM2 around the center of resistance, presenting a tipback moment. With various uprighting approaches, either conventional methods or skeletal anchorage devices, to provide pushing/pulling force, tipped molars can be easily corrected. Conclusions: Mandibular second molar impaction is a challenging disturbance that requires proper clinical, radiological, biomechanical evaluation, and suitable treatment option and appliance selection for successful treatment result.

Prevalence of Sleep Disordered Breathing in Orthodontic Patients and its Effect on Quality of Life and Craniofacial Morphology

Prevalence of Sleep Disordered Breathing in Orthodontic Patients and its Effect on Quality of Life and Craniofacial Morphology