Craniofacial Skeletal Morphology Research Articles

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.

An orthodontic perspective on Larsen syndrome

BackgroundLarsen syndrome (LS) is a rare disorder of osteochondrodysplasia. In addition to large-joint dislocations, craniofacial anomalies are typical characteristics. In this report, we performed orthodontic analyses, including skeletal and occlusal evaluations, to examine whether the craniofacial skeletal morphology leads to the craniofacial anomalies in LS.Case presentationA 5 year old Japanese girl who was clinically diagnosed with LS was referred to the orthodontic clinic in the Fukuoka Dental College Medical and Dental Hospital because of a malocclusion. Clinical findings at birth were knee-joint dislocations, equinovarus foot deformities, and cleft soft palate. The patient showed craniofacial anomalies with hypertelorism, prominent forehead, depressed nasal bridge, and flattened midface. To evaluate the craniofacial skeletal morphology, cephalometric analysis was performed. In the frontal cephalometric analysis, the larger widths between bilateral points of the orbitale were related to hypertelorism. The lateral cephalometric analysis revealed the midface hypoplasia and the retrognathic mandible. These findings were responsible for the flattened appearance of the patient’s face, even if the anteroposterior position of the nasion was normal. Her forehead looked prominent in relation to the face probably because of the retrognathic maxilla and mandible. Both the study model and the frontal cephalometric analysis indicated constriction of the upper and lower dental arches. The posterior crossbite facilitated by the premature contacts had developed in association with the constriction of the upper dental arch.ConclusionsThis patient had some craniofacial anomalies with characteristic appearances in LS. It was evident that the underlying skeletal morphology led to the craniofacial dysmorphism.

Geometric morphometric investigation of craniofacial morphological change in domesticated silver foxes

To test the effects of domestication on craniofacial skeletal morphology, we used three-dimensional geometric morphometrics (GM) along with linear and endocranial measurements to compare selected (domesticated) and unselected foxes from the Russian Farm-Fox Experiment to wild foxes from the progenitor population from which the farmed foxes are derived. Contrary to previous findings, we find that domesticated and unselected foxes show minimal differences in craniofacial shape and size compared to the more substantial differences between the wild foxes and both populations of farmed foxes. GM analyses and linear measurements demonstrate that wild foxes differ from farmed foxes largely in terms of less cranial base flexion, relatively expanded cranial vaults, and increased endocranial volumes. These results challenge the assumption that the unselected population of foxes kept as part of the Russian Farm-Fox experiment are an appropriate proxy for ‘wild’ foxes in terms of craniofacial morphology and highlight the need to include wild populations in further studies of domestication syndrome to disentangle the phenotypic effects of multiple selection pressures. These findings also suggest that marked increases in docility cannot be reliably diagnosed from shape differences in craniofacial skeletal morphology.

Evaluation of the morphometric covariation between palatal and craniofacial skeletal morphology in class III malocclusion growing subjects

BackgroundTo study the covariation between palatal and craniofacial skeletal morphology in Class III growing patients through geometric morphometric analysis (GMM).MethodsIn this retrospective study, 54 Class III subjects (24F,30M;7.6 ± 0.8yy) were enrolled following these inclusion criteria: European ancestry, Class III skeletal and dental relationship, early mixed dentition, prepubertal skeletal maturation, familiarity for Class III malocclusion, no pseudo Class III malocclusion. Each patient provided upper digital cast and cephalogram before starting the therapy. Landmarks and semilandmarks were digitized (239 on the casts;121 on the lateral radiographs) and GMM was used. Procrustes analysis and principal component analysis (PCA) were applied to show the principal components of palatal and craniofacial skeletal shape variation. Two-block partial least squares analysis (PLS) was used to assess pattern of covariation between palatal and craniofacial morphology.ResultsRegarding palatal shape variation, PC with largest variance (PC1) described morphological changes in the three space dimensions, while, concerning the craniofacial complex components, PC1 revealed morphological differences along the vertical plane. A significant covariation was found between palatal and craniofacial shape. PLS1 accounted for more than 61,7% of the whole covariation, correlating the craniofacial divergence to palatal height and width.ConclusionsIn Class III subjects increments of angle divergence are related to a narrow and high palate.

Development and Validation of Novel Three-Dimensional Craniofacial Landmarks on Cone-Beam Computed Tomography Scans.

As cone-beam computed tomography (CBCT) scans become increasingly common, it is vital to have reliable 3-dimensional (3D) landmarks for quantitative analysis of craniofacial skeletal morphology. While some studies have developed and used 3D landmarks, these landmark sets are generally small and derived primarily from previous 2-dimensional (2D) cephalometric landmarks. These derived landmarks lack information in parts of the skull such as the cranial base, which is an important feature for cranial growth and development. The authors see a real need for development and validation of 3D landmarks, particularly bilateral landmarks, across the skull for improved cephalometric analysis. The primary objective of this study is to develop and validate a set of 61 3D anatomical landmarks on the face, cranial base, mandible, and teeth for use in clinical and research studies involving CBCT imaging. Each landmark was placed 3 times by 3 separate trained observers on a set of 10 anonymized CBCT patient scans. Intra-rater and inter-rater estimates of consistency and agreement were calculated using the intraclass correlation coefficient. Measurement error was calculated per landmark and per X, Y, and Z landmark coordinate. The authors had high ICC estimates within rates, indicating high consistency, and high ICC estimates among raters, indicate good agreement across raters. Overall measurement error for each landmark and each X, Y, and Z coordinate was low. Our results confirm the accuracy of novel 3D landmarks including several on the cranial base that will serve researchers and clinicians for use in future studies involving 3D CBCT imaging and craniofacial development.

Tooth agenesis-related GLI2 and GLI3 genes may contribute to craniofacial skeletal morphology in humans

ObjectiveThe present cross-sectional, multi-centre, genetic study aimed to determine, whether single nucleotide polymorphisms (SNPs) in tooth agenesis (TA)-associated GLI2 and GLI3 genes contribute to the development of craniofacial skeletal morphology in humans. DesignOrthodontic patients from an ethnically heterogeneous population were selected for the present study (n = 594). The presence or absence of TA was determined by analysis of panoramic radiography and dental records. The subjects were classified according to their skeletal malocclusion and facial growth pattern by means of digital cephalometric analysis. Genomic DNA was extracted from squamous epithelial cells of the buccal mucosa and SNPs in GLI2 (rs3738880, rs2278741) and GLI3 (rs929387, rs846266) were analysed by polymerase chain reaction using TaqMan chemistry and end-point analysis. ResultsClass II skeletal malocclusion presented a significantly lower frequency of TA (P < 0.05). Subjects without TA showed significantly higher ANB angles (P < 0.05). Genotype and/or allele distributions of the SNPs in GLI2 (rs3738880, rs2278741) and GLI3 (rs846266) were associated with the presence of TA (P < 0.05). The SNPs rs3738880, rs2278741 and rs929387 were also associated with some type of skeletal malocclusion (P < 0.05), but not with the facial growth pattern (P > 0.05). The G allele for TA-related GLI2 rs3738880 was strongly linked to the presence of Class III skeletal malocclusion (OR = 2.03; 95% CI = 1.37–3.03; P<3125 × 10−6). GLI2 rs2278741 C allele was overrepresented in individuals without TA, suggesting it as a protective factor for this dental phenotype (OR = 0.43; 95% CI = 0.24−0.78; P<625 × 10−5). ConclusionThe present study suggests that SNPs in TA-associated GLI2 and GLI3 genes may also play a role in the development of skeletal malocclusions. rs3738880 and rs2278741 in GLI2 seems to contribute to the genetic background for skeletal Class III and TA, respectively. TA could be an additional predictor of craniofacial morphology in some cases. Further research replicating the reported associations should be performed.

Effects of Craniofacial Morphology on Nasal Respiratory Function and Upper Airway Morphology.

Craniofacial skeletal patterns change after orthognathic surgery. The present study aimed to investigate the effects of different craniofacial patterns on nasal respiratory function and the upper airway. Forty-seven healthy subjects were selected and divided into 3 groups according to their mandibular position. Sixteen were in the skeletal Class I group, 15 were in the skeletal Class II group, and 16 were in the skeletal Class III group. Cone beam computed tomography was performed, and nasal airflow and nasal resistance were measured. Differences in nasal respiratory functions and upper airway were compared among the groups. A correlation analysis was conducted for nasal respiratory function, upper airway, and skeletal patterns. There were significant differences among the 3 groups regarding dominant-side nasal inspiratory capacity (P = 0.001), bilateral nasal inspiratory capacity (P = 0.005), nasal partitioning ratio-inspiration (P = 0.007), and velopharyngeal minimum cross-sectional area (P = 0.029). The values were significantly higher for the skeletal Class III group than the skeletal Class I and II groups. A correlation analysis showed that the nasal partitioning ratio and nasal airway resistance were mostly negatively correlated with SNA, but the upper airway volume and cross-sectional area were positively correlated with SNB and negatively correlated with ANB. The dominant-side nasal expiratory capacity was mainly negatively correlated with the mean velopharyngeal cross-sectional area (r = -0.324, P = 0.026), mean glossopharyngeal cross-sectional area (Glosso-A mean) (r = -0.293, P = 0.046), and mean total airway cross-sectional area (Total-A mean) (r = -0.307, P = 0.036). Craniofacial skeletal morphology may affect nasal respiratory function and the upper airway.

An orthodontic–orthognathic conceptual approach to OSAS surgery: our experience and results

Introduction It is well recognised that obstructive sleep apnea syndrome is linked with upper airway obstruction during sleep. The psychomotor sequelae of OSAS, including excessive daytime sleepiness, cefalea, daytime fatigue, increased cardiovascular morbidity and mortality and poor sleep quality with performance impairment due to sleep fragmentation, are also well described. In 1983 Powell and coauthors described the first mandibular advancement (MMA) to treat OSAS and subsequently they advocated simultaneous maxillary and mandibular advancement in an attempt to improve results. Materials and methods Nowadays, the surgical techniques, borrowed from orthognathic surgery are used with great success in surgical OSAS treatment. Long-term success with MMA is valuable in 90–100% of cases. This surgical approach has been shown repeatedly to be a highly effective treatment modality for OSAS in patients with maxillo-mandibular deficiency, but also in OSAS patients without maxillo-mandibular deficiency with equally successful outcomes. The aesthetic appearance of a patient, who exhibits normal craniofacial skeletal morphology, will get worse after surgical procedure leading to a biprotrusion profile. When planning the surgery, the surgeon has to consider the aesthetic deterioration degree in order to obtain the maximum enlargement of the upper airway whilst maintaining an acceptable aesthetic. Concerning the efforts to minimize the aesthetic impairment, pre-surgical orthodontic treatment and, subsequent, orthognathic surgery may improve the aesthetic and functional treatment results. Results The authors describe their approach to OSAS presenting a 10 patients series composed of very different kinds of maxillo-mandibular conditions related to OSAS. We reached a 100% success for AHI Conclusion MMA as described in the literature concerned with the forward reposition of maxillo-mandibular complex preserving the personal dental occlusion.Using the CPAP support during presurgical orthodontic preparation we can spend some time to normalize dental arches form and compensation in order to obtain at surgery the best skeletal position and dental occlusion. Even the eumorphic patients can take advantage of presurgical orthodontic treatment, the orthodontist may plan the best occlusion according to the MMA. It entails a more stable dental occlusion which itself fights against the deterioration tendency of the surgical result. Pre-surgical orthodontic treatment qualifies as orthognathic surgery even in OSAS patients.

Craniofacial skeletal architecture and obstructive sleep apnoea syndrome severity

Obstructive sleep apnoea syndrome (OSAS) is a sleep related breathing disorder caused by pharynx obstruction that often terminates in abrupt arousals and is capable of disrupting physiological sleep profile. Its' severity has been associated, among others, with craniofacial skeletal morphology. To investigate this relationship and elucidate craniofacial skeleton patterns in individuals without obvious maxillofacial abnormalities, 171 OSAS patients were studied with nocturnal polysomnographic record and chephalometric X-ray (24 variables). Chephalometric variables were compared between three apnoea/hypopnoea index (AHI) groups (AHI ≤ 15; 15 < AHI < 30; AHI ≥ 30) and uni/multivariate analysis between chephalometric variables and AHI were performed.The patients were predominantly men (83%), with a mean age of 48.1 years. Mean BMI and AHI were 28.4 kg/m2 and 26.2, respectively. Most chephalometric variables differed among the three AHI groups. Fifteen chephalometric variables showed a correlation with AHI. Five chephalometric variables and BMI were independent AHI predictors. Chephalometric variables were better AHI predictors in normal weight patients.Significant evidence of craniofacial skeleton influence was found on OSAS severity, caudalization of the hyoid and lower sagittal facial projection being the most important patterns. From the chephalometric variables analysed, the hypopharynx calibre demonstrated a higher predictive value for AHI, independently of BMI.

In vivo bone strain and finite-element modeling of the craniofacial haft in catarrhine primates

Hypotheses regarding patterns of stress, strain and deformation in the craniofacial skeleton are central to adaptive explanations for the evolution of primate craniofacial form. The complexity of craniofacial skeletal morphology makes it difficult to evaluate these hypotheses with in vivo bone strain data. In this paper, new in vivo bone strain data from the intraorbital surfaces of the supraorbital torus, postorbital bar and postorbital septum, the anterior surface of the postorbital bar, and the anterior root of the zygoma are combined with published data from the supraorbital region and zygomatic arch to evaluate the validity of a finite-element model (FEM) of a macaque cranium during mastication. The behavior of this model is then used to test hypotheses regarding the overall deformation regime in the craniofacial haft of macaques. This FEM constitutes a hypothesis regarding deformation of the facial skeleton during mastication. A simplified verbal description of the deformation regime in the macaque FEM is as follows. Inferior bending and twisting of the zygomatic arches about a rostrocaudal axis exerts inferolaterally directed tensile forces on the lateral orbital wall, bending the wall and the supraorbital torus in frontal planes and bending and shearing the infraorbital region and anterior zygoma root in frontal planes. Similar deformation regimes also characterize the crania of Homo and Gorilla under in vitro loading conditions and may be shared among extant catarrhines. Relatively high strain magnitudes in the anterior root of the zygoma suggest that the morphology of this region may be important for resisting forces generated during feeding.

13 顔面頭蓋骨格の形態分析における超音波画像の応用(第506回 大阪歯科学会例会)

13 顔面頭蓋骨格の形態分析における超音波画像の応用(第506回 大阪歯科学会例会)

Predisposing Factors to Formation of Cleft Lip and Palate: Inherited Craniofacial Skeletal Morphology

To identify inherited craniofacial morphologic features in individuals at high risk for cleft of the lip, cleft palate, or both. Twins without cleft from 33 pairs of monozygotic twins discordant for cleft lip, cleft palate, or both were studied. There were 17 males and 16 females of Caucasian origin, ranging from 3 to 18 years (15 with cleft lip and palate [CLP], 10 with cleft lip [CL], and 8 with cleft palate [CP]), collected from five craniofacial centers (United States and Canada). The twin without cleft (noncleft) from each set was compared with an age- and sex-matched control individual from the Burlington Growth Centre, Toronto, Ontario. Posteroanterior and lateral cephalograms were traced and digitized using a computer custom analysis. Descriptive statistics, Student's t tests, and analysis of variance were used to test 40 variables in a pilot study comparing the noncleft twin groups with the controls. Preliminary analysis permitted pooling of the CLP and CL groups (n = 25). To minimize false-positive significance, only 14 variables (from the maxillofacial area) were tested. Using the raw probabilities, eight variables showed significant differences between the pooled noncleft CLP and CL (CL[P]) twin group and the controls. However, when the level of significance was adjusted, only four (nasal width [p < .01], cranial base length [p < .05], cranial base width/length ratio [p < .001], and maxillary width/length ratio [p < .05]) were significantly different. No significant differences were confirmed between the noncleft CP twin group and the controls. The noncleft member of a discordant monozygotic pair has a number of facial characteristics that differ from the general population. These may predispose to the formation of a cleft lip or palate and may result from a deficiency or distortion of the mesenchyme that forms the craniofacial structures.