Caries Incidence Is Associated with Wasting among Cambodian Children

Evidence suggests that dental caries is associated with chronic and acute malnutrition, manifested as stunting and wasting in children. However, studies have not always appropriately accounted for confounding factors or for the temporal ordering between exposure and outcome. This study examined relationships between the development of caries lesions with subsequent stunting and wasting outcomes using data from a population-based cohort in Cambodia. Caries incidence was assessed based on the presence of a new cavitated carious lesion or a new pulpally involved lesion across a 6-mo observation period. Anthropometric measurements were taken at regular intervals. Effects of carious lesions on stunting and wasting were assessed using inverse probability treatment weighting, adjusting for potential confounders, using z scores for height-for-age (HAZ) and weight-for-height (WHZ) as outcomes. In total, 894 children (mean age 20 mo at baseline) were followed over 2 y. At baseline, 350 (39.1%) were identified as having stunting malnutrition. At follow-up, 58 (6.5%) had a new pulpally involved lesion. There was no association between incidence of cavitated or pulpally involved carious lesions at follow-up and stunting (relative risk [RR] = 1.06; 95% confidence interval [CI]: 0.75, 1.50). The incidence of pulpally involved carious lesions had an effect on wasting prevalence (WHZ <-2; RR = 1.35; 95% CI: 0.70, 2.62) and WHZ scores (average treatment effect = -0.294; 95% CI: -0.538, -0.050). This study offers evidence that the development of pulpally involved carious lesions has an effect on WHZ scores. Oral health promotion and clinical prevention and management of dental caries should be explored as interventions to promote normal growth and development among preschool children, particularly in low-income settings.

Cranial Base Synchondrosis Lacks PTHrP-Expressing Column-Forming Chondrocytes

The cranial base contains a special type of growth plate termed the synchondrosis, which functions as the growth center of the skull. The synchondrosis is composed of bidirectional opposite-facing layers of resting, proliferating, and hypertrophic chondrocytes, and lacks the secondary ossification center. In long bones, the resting zone of the epiphyseal growth plate houses a population of parathyroid hormone-related protein (PTHrP)-expressing chondrocytes that contribute to the formation of columnar chondrocytes. Whether PTHrP⁺ chondrocytes in the synchondrosis possess similar functions remains undefined. Using Pthrp-mCherry knock-in mice, we found that PTHrP⁺ chondrocytes predominantly occupied the lateral wedge-shaped area of the synchondrosis, unlike those in the femoral growth plate that reside in the resting zone within the epiphysis. In vivo cell-lineage analyses using a tamoxifen-inducible Pthrp-creER line revealed that PTHrP⁺ chondrocytes failed to establish columnar chondrocytes in the synchondrosis. Therefore, PTHrP⁺ chondrocytes in the synchondrosis do not possess column-forming capabilities, unlike those in the resting zone of the long bone growth plate. These findings support the importance of the secondary ossification center within the long bone epiphysis in establishing the stem cell niche for PTHrP⁺ chondrocytes, the absence of which may explain the lack of column-forming capabilities of PTHrP⁺ chondrocytes in the cranial base synchondrosis.

Maturation of the oral microbiota during primary teeth eruption: a longitudinal, preliminary study

Introduction

Oral microbiota that established in the early years of life may influence the child’s oral health in the long term. Until now, no consensus is reached about whether the development of the oral microbiota is more related with age increase or more with teeth eruption.

Objective

To analyze the microbiota development of both saliva and supragingival plaque during the gradual eruption of primary teeth in caries-free infants and toddlers.

Methods

Saliva and plaque samples were collected at five and four dentition states, respectively, and were identified by bacterial 16S rRNA gene sequencing.

Results

During the longitudinal observation, the saliva ecosystem seemed more complex and dynamic than the plaque, with larger bacteria quantity and more significantly varied species over time. About 70% of the initial colonized OTUs in plaque persisted until the completion of the primary dentition. Transient bacteria were mostly detected in the early saliva and plaque microbiota, which came from the environment and other sites of the human body. Microbial diversity in both saliva and plaque varied greatly from pre-dentition to full eruption of eight anterior teeth, but not during the eruption of primary molars.

Conclusion

Oral bacterial development follows an ordered sequence during the primary teeth eruption. ‘Fully eruption of all primary anterior teeth’ is a critical stage in this process.

METTL3-Dependent Glycolysis Regulates Dental Pulp Stem Cell Differentiation

N⁶-methyladenosine (m⁶A) is a eukaryotic messenger RNA modification catalyzed by methyltransferase-like 3 (METTL3), which is involved in various developmental and disease processes. However, the connection between the epigenetic modification of m⁶A and glucose metabolism during osteogenesis is still unclear. Here, we show that interference with METTL3 in dental pulp stem cells (DPSCs) inhibits cell proliferation and osteogenic differentiation. Moreover, transcriptome sequencing and metabolic testing were used to explore the mechanism between glucose metabolism and m⁶A modification in METTL3-knockdown DPSCs. Methylated RNA immunoprecipitation-quantitative polymerase chain reaction and RNA stability assays were used to determine the target genes of METTL3. Mechanistically, METTL3 directly interacts with ATP citrate lyase (ACLY) and a mitochondrial citrate transporter (SLC25A1) and then further affects the glycolytic pathway. M⁶A-mediated ACLY and SLC25A1 stability depends on the m⁶A readers IGF2BP2 and IGF2BP2/3, respectively. Our experiments uncovered the potential molecular mechanism of epigenetic modification in osteogenic differentiation, providing new ideas for the clinical application of stem cells and the intervention of metabolic bone diseases.

Identifying students who are off-track academically at the start of secondary school: The role of social-emotional learning trajectories

BACKGROUND

Research shows that successfully transitioning from intermediate school to secondary school is pivotal for students to remain on track to graduate. Studies also indicate that a successful transition is a function not only of how prepared the students are academically but also whether they have the social-emotional learning (SEL) skills to succeed in a more independent secondary school environment.

AIM

Yet, little is known about whether students' SEL skills are stable over time, and if they are not, whether a student's initial level of SEL skills at the start of intermediate school or change in SEL skills over time is a better indicator of whether the student will be off track academically in 9th grade. This study begins to investigate this issue.

SAMPLE

We use four years of longitudinal SEL data from students in a large urban district with a sample size of ˜3,000 students per timepoint.

METHODS

We use several years of longitudinal SEL data to fit growth models for three constructs shown to be related to successfully transitioning to secondary school. In so doing, we examine whether a student's mean SEL score in 6th grade (status) or growth between 6th and 8th grade is more predictive of being off track academically in 9th grade.

RESULT

Results indicate that, while status is more frequently significant, growth for self-management is also predictive above and beyond status on that construct.

CONCLUSION

Findings suggest that understanding how a student develops social-emotionally can improve identification of students not on track to succeed in high school.

Third Molar Agenesis Is Associated with Facial Size

Simple Summary

Missing third molars is a common occurrence in modern humans with a prevalence of approximately 20% in the general population. The absence of those teeth, however, is not found in other human predecessors. Therefore, there is speculation whether the congenital absence of third molars is part of an evolutionary mechanism that leads to smaller jaws, smaller and fewer teeth, or if their absence is associated with more local developmental factors. In this study, we assessed the size of the cranial base, the maxilla, the mandible and the entire craniofacial complex in individuals missing one or more third molars and compared them with a group with no missing teeth. We showed that in cases with one or more missing third molars, there is a significant decrease in the size of the maxilla, the mandible as well as the entire facial configuration. Additionally, the more missing third molars, the smaller the jaws and the face were. These findings suggest that isolated third molar agenesis is part of a developmental mechanism related to craniofacial size reduction. Whether this mechanism is part of an evolutionary process in humans remains to be seen.

Abstract

Individuals with congenitally missing permanent teeth, other than third molars, present smaller craniofacial configurations compared to normal controls. However, it is not known if agenesis of third molars is part of the same mechanism. Therefore, this study assessed individuals with and without isolated third molar agenesis and tested the relation of this condition to the size of their facial configurations, using geometric morphometric methods. We show that the absence of one or more third molars is associated with a smaller maxilla, smaller mandible and a smaller overall facial configuration. The effect was larger as the number of missing third molars increased. For example, the size of the mandibular centroids in five 16-year-old females with no, one, two, three or four missing third molars showed a size reduction of approximately 2.5 mm per missing third molar. In addition, in cases with third molar agenesis in one jaw only, the effect was also evident on the opposite jaw. Our findings suggest that isolated third molar agenesis is part of a developmental mechanism resulting also in craniofacial size reduction. This might be the effect of an evolutionary process observed in humans, leading to fewer and smaller teeth, as well as smaller facial structures.

Advanced 3D Models Cultured to Investigate Mesenchymal Stromal Cells of the Human Dental Follicle

The human dental follicle (hDF) contains the developing tooth and is involved in regulating tooth maturation and eruption. To investigate the mesenchymal stromal cells of the dental follicle, 2 three-dimensional (3D) culture models were used, based on a dynamic bioreactor: the Rotary Cell Culture System (RCCS™) and the 3D culture of precursor cells isolated from follicular tissue (human dental follicle cells [hDFCs]). The hDFCs were obtained from impacted third molars of 20 patients. Two 3D culture models were tested. In the first model, intact hDF explants were cultured in 3D conditions, preserving the original tissue architecture; they were studied using histomorphological and molecular analyses. The second model involved the 3D culture of hDFCs, which were characterized to evaluate their multipotency in terms of differentiation capability. Of the biomarkers known to characterize hDFCs, hDF precursors were selected for our study. The immunophenotype and in situ immunocytochemistry were evaluated for markers CD44, CD90, CD146, CD105, CD31, CD34, and CD45 Ag. The results show that the conditions provided by the RCCS preserve the original organizational architecture of the cells. The 3D conditions of the model enhanced differentiation in response to adipogenic, osteogenic, and chondrogenic inductive growth media. The immunophenotype and the immunocytochemistry showed generally high expression of CD90, CD44, and CD105, while CD146 expression was more restricted to ∼30% of cells. No expression was observed for CD31, CD34, and CD45 Ags. Two 3D tissue- and cell-based ex vivo models of the hDF supported the long-term maintenance of hDF-specific cell phenotypes and their ability to recapitulate typical cellular differentiation states. As such, these ex vivo models could be used to study the physiopathology of human odontogenesis. In addition, in a therapeutic context, they could be used to examine the role of specific chemical signals (e.g., new therapeutic agents) in the processes of dental tissue repair and regeneration.

Vital Roles of β-catenin in Trans-differentiation of Chondrocytes to Bone Cells

A recent breakthrough showing that direct trans-differentiation of chondrocytes into bone cells commonly occurs during endochondral bone formation in the growth plate, articular cartilage, and mandibular condylar cartilage suggests that chondrogenesis and osteogenesis are likely one continuous biological process instead of two separate processes. Yet, gene regulation of this cell transformation is largely unclear. Here, we employed cartilage-specific β-catenin loss-of-function (β-catenin ^fx/fx ) and gain-of-function (β-catenin ^{fx(exon3)/ fx(exon3)} ) models in the R26R^Tomato background (for better tracing the cell fate of chondrocytes) to study the role of β-catenin in cell trans-differentiation. Using histological, immunohistochemical, and radiological methods combined with cell lineage tracing techniques, we showed that deletion of β-catenin by either Acan-Cre^ERT2 or Col10a1-Cre resulted in greatly reduced cell trans-differentiation with a significant decrease in subchondral bone volume during mandibular condylar growth. Molecular studies demonstrated severe defects in cell proliferation and differentiation in both chondrocytes and bone cells. The gain of function studies (constitutive activation of β-catenin with Acan-Cre^ERT2 at ages of postnatal day 7, 4-weeks and 6-months) led to more bone cell trans-differentiation of chondrocytes in the mandibular condyle due to increased proliferation and accelerated chondrocyte differentiation with incipient osteogenic changes within the cartilage matrix, resulting in an increased volume of poorly-formed immature subchondral bone. These results support the notion that chondrogenesis and osteogenesis are one continuous process, in which β-catenin signaling plays an essential role in the cell trans-differentiation of chondrocytes into bone cells during mandibular condylar development and growth.

Plunging ranula: surgical management of case series and the literature review

Plunging ranulas are rare; report of this condition is particularly limited in our environment. We present case series in children; with all cases having both oral and cervical components. It is important to note this type of presentation of plunging ranula and their appropriate management.

Selective Role of Discoidin Domain Receptor 2 in Murine Temporomandibular Joint Development and Aging

Temporomandibular joint (TMJ) disorders are often associated with development of osteoarthritis-like changes in the mandibular condyle. Discoidin domain receptor 2 (DDR2), a collagen receptor preferentially activated by type I and III collagen found in the TMJ and other fibrocartilages, has been associated with TMJ degeneration, but its role in normal joint development has not been previously examined. Using Ddr2 LacZ-tagged mice and immunohistochemistry, we found that DDR2 is preferentially expressed and activated in the articular zone of TMJs but not knee joints. To assess the requirement for Ddr2 in TMJ development, studies were undertaken to compare wild-type and smallie ( slie) mice, which contain a spontaneous deletion in Ddr2 to produce an effective null allele. Analysis of TMJs from newborn Ddr2^slie/slie mice revealed a developmental delay in condyle mineralization, as measured by micro-computed tomography and histologic analysis. In marked contrast, knee joints of Ddr2^slie/slie mice were normal. Analysis of older Ddr2^slie/slie mice (3 and 10 mo) revealed that the early developmental delay led to a dramatic and progressive loss of TMJ articular integrity and osteoarthritis-like changes. Mutant condyles had a rough and flattened bone surface, accompanied by a dramatic loss of bone mineral density. Mankin scores showed significantly greater degenerative changes in the TMJs of 3- and 10-mo-old Ddr2^slie/slie mice as compared with wild-type controls. No DDR2-dependent degenerative changes were seen in knees. Analysis of primary cultures of TMJ articular chondrocytes from wild-type and Ddr2^slie/slie mice showed defects in chondrocyte maturation and mineralization in the absence of Ddr2. These studies demonstrate that DDR2 is necessary for normal TMJ condyle development and homeostasis and that these DDR2 functions are restricted to TMJ fibrocartilage and not seen in the hyaline cartilage of the knee.

Ciliopathy Protein Tmem107 Plays Multiple Roles in Craniofacial Development

A broad spectrum of human diseases called ciliopathies is caused by defective primary cilia morphology or signal transduction. The primary cilium is a solitary organelle that responds to mechanical and chemical stimuli from extracellular and intracellular environments. Transmembrane protein 107 (TMEM107) is localized in the primary cilium and is enriched at the transition zone where it acts to regulate protein content of the cilium. Mutations in TMEM107 were previously connected with oral-facial-digital syndrome, Meckel-Gruber syndrome, and Joubert syndrome exhibiting a range of ciliopathic defects. Here, we analyze a role of Tmem107 in craniofacial development with special focus on palate formation, using mouse embryos with a complete knockout of Tmem107. Tmem107^-/- mice were affected by a broad spectrum of craniofacial defects, including shorter snout, expansion of the facial midline, cleft lip, extensive exencephaly, and microphthalmia or anophthalmia. External abnormalities were accompanied by defects in skeletal structures, including ossification delay in several membranous bones and enlargement of the nasal septum or defects in vomeronasal cartilage. Alteration in palatal shelves growth resulted in clefting of the secondary palate. Palatal defects were caused by increased mesenchymal proliferation leading to early overgrowth of palatal shelves followed by defects in their horizontalization. Moreover, the expression of epithelial stemness marker SOX2 was altered in the palatal shelves of Tmem107^-/- animals, and differences in mesenchymal SOX9 expression demonstrated the enhancement of neural crest migration. Detailed analysis of primary cilia revealed region-specific changes in ciliary morphology accompanied by alteration of acetylated tubulin and IFT88 expression. Moreover, Shh and Gli1 expression was increased in Tmem107^-/- animals as shown by in situ hybridization. Thus, TMEM107 is essential for proper head development, and defective TMEM107 function leads to ciliary morphology disruptions in a region-specific manner, which may explain the complex mutant phenotype.

Candidate Genes for Nonsyndromic Cleft Palate Detected by Exome Sequencing

Nonsyndromic cleft palate only (nsCPO) is a facial malformation that has a livebirth prevalence of 1 in 2,500. Research suggests that the etiology of nsCPO is multifactorial, with a clear genetic component. To date, genome-wide association studies have identified only 1 conclusive common variant for nsCPO, that is, a missense variant in the gene grainyhead-like-3 ( GRHL3). Thus, the underlying genetic causes of nsCPO remain largely unknown. The present study aimed at identifying rare variants that might contribute to nsCPO risk, via whole-exome sequencing (WES), in multiply affected Central European nsCPO pedigrees. WES was performed in 2 affected first-degree relatives from each family. Variants shared between both individuals were analyzed for their potential deleterious nature and a low frequency in the general population. Genes carrying promising variants were annotated for 1) reported associations with facial development, 2) multiple occurrence of variants, and 3) expression in mouse embryonic palatal shelves. This strategy resulted in the identification of a set of 26 candidate genes that were resequenced in 132 independent nsCPO cases and 623 independent controls of 2 different ethnicities, using molecular inversion probes. No rare loss-of-function mutation was identified in either WES or resequencing step. However, we identified 2 or more missense variants predicted to be deleterious in each of 3 genes ( ACACB, PTPRS, MIB1) in individuals from independent families. In addition, the analyses identified a novel variant in GRHL3 in 1 patient and a variant in CREBBP in 2 siblings. Both genes underlie different syndromic forms of CPO. A plausible hypothesis is that the apparently nonsyndromic clefts in these 3 patients might represent hypomorphic forms of the respective syndromes. In summary, the present study identified rare variants that might contribute to nsCPO risk and suggests candidate genes for further investigation.

Molecular and Cellular Mechanisms of Palate Development

Development of the mammalian secondary palate involves highly dynamic morphogenetic processes, including outgrowth of palatal shelves from the oral side of the embryonic maxillary prominences, elevation of the initially vertically oriented palatal shelves to the horizontal position above the embryonic tongue, and subsequently adhesion and fusion of the paired palatal shelves at the midline to separate the oral cavity from the nasal cavity. Perturbation of any of these processes could cause cleft palate, a common birth defect that significantly affects patients' quality of life even after surgical treatment. In addition to identifying a large number of genes required for palate development, recent studies have begun to unravel the extensive cross-regulation of multiple signaling pathways, including Sonic hedgehog, bone morphogenetic protein, fibroblast growth factor, transforming growth factor β, and Wnt signaling, and multiple transcription factors during palatal shelf growth and patterning. Multiple studies also provide new insights into the gene regulatory networks and/or dynamic cellular processes underlying palatal shelf elevation, adhesion, and fusion. Here we summarize major recent advances and integrate the genes and molecular pathways with the cellular and morphogenetic processes of palatal shelf growth, patterning, elevation, adhesion, and fusion.

Circulatory CNP Rescues Craniofacial Hypoplasia in Achondroplasia

Achondroplasia is the most common genetic form of human dwarfism, characterized by midfacial hypoplasia resulting in occlusal abnormality and foramen magnum stenosis, leading to serious neurologic complications and hydrocephalus. Currently, surgery is the only way to manage jaw deformity, neurologic complications, and hydrocephalus in patients with achondroplasia. We previously showed that C-type natriuretic peptide (CNP) is a potent stimulator of endochondral bone growth of long bones and vertebrae and is also a potent stimulator in the craniofacial region, which is crucial for midfacial skeletogenesis. In this study, we analyzed craniofacial morphology in a mouse model of achondroplasia, in which fibroblast growth factor receptor 3 (FGFR3) is specifically activated in cartilage ( Fgfr3^ach mice), and investigated the mechanisms of jaw deformities caused by this mutation. Furthermore, we analyzed the effect of CNP on the maxillofacial area in these animals. Fgfr3^ach mice exhibited midfacial hypoplasia, especially in the sagittal direction, caused by impaired endochondral ossification in craniofacial cartilage and by premature closure of the spheno-occipital synchondrosis, an important growth center in craniomaxillofacial skeletogenesis. We crossed Fgfr3^ach mice with transgenic mice in which CNP is expressed in the liver under the control of the human serum amyloid-P component promoter, resulting in elevated levels of circulatory CNP ( Fgfr3^ach/SAP-Nppc-Tg mice). In the progeny, midfacial hypoplasia in the sagittal direction observed in Fgfr3^ach mice was improved significantly by restoring the thickness of synchondrosis and promoting proliferation of chondrocytes in the craniofacial cartilage. In addition, the foramen magnum stenosis observed in Fgfr3^ach mice was significantly ameliorated in Fgfr3^ach/SAP-Nppc-Tg mice due to enhanced endochondral bone growth of the anterior intraoccipital synchondrosis. These results clearly demonstrate the therapeutic potential of CNP for treatment of midfacial hypoplasia and foramen magnum stenosis in achondroplasia.

Role of Primary Cilia in Odontogenesis

Primary cilium is a solitary organelle that emanates from the surface of most postmitotic mammalian cells and serves as a sensory organelle, transmitting the mechanical and chemical cues to the cell. Primary cilia are key coordinators of various signaling pathways during development and maintenance of tissue homeostasis. The emerging evidence implicates primary cilia function in tooth development. Primary cilia are located in the dental epithelium and mesenchyme at early stages of tooth development and later during cell differentiation and production of hard tissues. The cilia are present when interactions between both the epithelium and mesenchyme are required for normal morphogenesis. As the primary cilium coordinates several signaling pathways essential for odontogenesis, ciliary defects can interrupt the latter process. Genetic or experimental alterations of cilia function lead to various developmental defects, including supernumerary or missing teeth, enamel and dentin hypoplasia, or teeth crowding. Moreover, dental phenotypes are observed in ciliopathies, including Bardet-Biedl syndrome, Ellis-van Creveld syndrome, Weyers acrofacial dysostosis, cranioectodermal dysplasia, and oral-facial-digital syndrome, altogether demonstrating that primary cilia play a critical role in regulation of both the early odontogenesis and later differentiation of hard tissue-producing cells. Here, we summarize the current evidence for the localization of primary cilia in dental tissues and the impact of disrupted cilia signaling on tooth development in ciliopathies.

Thyroid Function during Early Life and Dental Development

Children with low levels of thyroid hormones (hypothyroidism) have delayed tooth eruption, enamel hypoplasia, micrognathia, and anterior open bite, whereas children with hyperthyroidism may suffer from accelerated tooth eruption, maxillary, and mandibular osteoporosis. However, it is still unknown whether thyroid function variations within the normal or subclinical range also have an impact on hard dental tissues in healthy children. The objective of this study was, therefore, to investigate the association between thyroid function from the fetal period until early childhood and dental development at school age. This study is embedded in the Generation R Study, a population-based cohort study established in Rotterdam, the Netherlands. Maternal thyroid function (thyroid-stimulating hormone [TSH], free thyroxine [FT4], and thyroid peroxidase antibody [TPOAb] concentrations) was measured during early pregnancy, and thyroid function of the offspring (TSH and FT4) was measured in cord blood at birth and in early childhood (6 y). Dental development was assessed from panoramic radiographs of children of school-going age (9 y). In total, 2,387 to 2,706 subjects were available for the multivariable linear regression analysis, depending on the point in time of thyroid function measurement. There was an inverse association between cord blood and early childhood TSH concentrations with dental development, with a -0.06 lower standard deviation (SD) per 1 mU/L of TSH (95% confidence interval [CI], -0.11 to -0.01) and a -0.06 lower SD per 1 mU/L of TSH (95% CI, -0.11 to 0.00), respectively. There was no association between the maternal thyroid function during pregnancy and the dental development score of the child. However, TPOAb-positive mothers had children with a -0.20 SD (adjusted 95% CI, -0.35 to -0.04) lower dental development score compared with TPOAb-negative mothers. The findings of this study suggest that the thyroid hormone is involved in the maturation of teeth from the early stages of life onward.

Variations in bone density across the body of the immature human mandible

During growth the mandible accommodates increases in biomechanical loading resulting from changes in the function of structures of the oral cavity. Biomechanical loads are thought to play an intricate and vital role in the modelling and remodelling of bone, with site-specific effects on bone mineral density. It is anticipated that the effects of this loading on bone mineral density are intensified during the functional transition from prenatal to postnatal stages. The aim of this study was thus to evaluate changes in bone mineral density across the body of the immature human mandible during the early stages of dental development. The study sample included 45 human mandibles, subdivided into three age groups: prenatal (30 gestational weeks to birth; n = 15); early postnatal (birth to 12 months; n = 18); and late postnatal (1-5 years; n = 12). Mandibles were scanned using X-ray micro-computed tomography. Eight landmarks were selected along the buccal/labial and lingual surfaces of each dental crypt for evaluation of the bone mineral density. Bone mineral density values were calculated using a reference standard and analysed using multivariate statistics. The bone mineral density of the lingual surface was found to be significantly higher (P ≤ 0.000) than that of the buccal/labial surface. Furthermore, bone mineral density in the alveolar region of the buccal/labial surface of the deciduous central incisor (P ≤ 0.001), the deciduous first molar (P ≤ 0.013) and lingual alveolar area of the deciduous second molar (P ≤ 0.032) were significantly greater in the early postnatal period than in the prenatal period. While changes in bone mineral density across the lingual surface were consistent with the progression of development and the biomechanical demand of the tongue as previously demonstrated, changes observed across the buccal/labial surface of the mandible appeared to accompany the advancing dental development. Thus, changes in bone mineral density across the mandible appear to be reflective of the stage of dental development and the level of biomechanical loading.

Oral Health-related Beliefs, Behaviors, and Outcomes through the Life Course

Complex associations exist among socioeconomic status (SES) in early life, beliefs about oral health care (held by individuals and their parents), and oral health-related behaviors. The pathways to poor adult oral health are difficult to model and describe, especially due to a lack of longitudinal data. The study aim was to explore possible pathways of oral health from birth to adulthood (age 38 y). We hypothesized that higher socioeconomic position in childhood would predict favorable oral health beliefs in adolescence and early adulthood, which in turn would predict favorable self-care and dental attendance behaviors; those would lead to lower dental caries experience and better self-reported oral health by age 38 y. A generalized structural equation modeling approach was used to investigate the relationship among oral health-related beliefs, behaviors in early adulthood, and dental health outcomes and quality of life in adulthood (age, 38 y), based on longitudinal data from a population-based birth cohort. The current investigation utilized prospectively collected data on early (up to 15 y) and adult (26 and 32 y) SES, oral health-related beliefs (15, 26, and 32 y), self-care behaviors (15, 28, and 32 y), oral health outcomes (e.g., number of carious and missing tooth surfaces), and oral health-related quality of life (38 y). Early SES and parental oral health-related beliefs were associated with the study members' oral health-related beliefs, which in turn predicted toothbrushing and dental service use. Toothbrushing and dental service use were associated with the number of untreated carious and missing tooth surfaces in adulthood. The number of untreated carious and missing tooth surfaces were associated with oral health-related quality of life. Oral health toward the end of the fourth decade of life is associated with intergenerational factors and various aspects of people's beliefs, SES, dental attendance, and self-care operating since the childhood years.

Molecular contribution to cleft palate production in cleft lip mice

Cleft palate following cleft lip may include a developmental disorder during palatogenesis. CL/Fr mice fetuses, which develop cleft lip and palate spontaneously, have less capability for in vivo cell proliferation in palatal mesenchyme compared with CL/Fr normal fetuses. In order to know the changes of signaling molecules contributing to cleft palate morphogenesis following cleft lip, the mRNA expression profiles were compared in palatal shelves oriented vertically (before elevation) in CL/Fr fetuses with or without cleft lip. The changes in mRNA profile of cleft palate morphogenesis were presented in a microarray analysis, and genes were restricted to lists contributing to cleft palate development in CL/Fr fetuses with cleft lip. Four candidate genes (Ywhab, Nek2, Tacc1 and Frk) were linked in a gene network that associates with cell proliferation (cell cycle, MAPK, Wnt and Tgf beta pathways). Quantitative real-time RT-PCR highlighted the candidate genes that significantly changed in CL/Fr fetuses with cleft lip (Ywhab, Nek2 and Tacc1). The results of these molecular contributions will provide useful information for a better understanding of palatogenesis in cleft palate following cleft lip. Our data indicated the genetic contribution to cleft palate morphogenesis following cleft lip.