Third Molar Comparison in Class I and II Extraction and Non-extraction Orthodontic Treatment: A Retrospective Longitudinal Study

Objective

This study compared third molar angulation and eruption status in Class I and II malocclusions after orthodontic treatment with and without first premolar extractions.

Methods

The sample comprised 93 patients divided into four groups: Group 1, Class I malocclusion treated with first premolar extractions; Group 2, Class I malocclusion treated without extractions; Group 3, Class II malocclusion treated with first premolar extractions; and Group 4, Class II malocclusion treated without extractions. Panoramic radiographs were used to evaluate the third molar mesiodistal angulations at T1 (pretreatment), T2 (posttreatment), and T3 (long-term posttreatment). Third molar eruption status was assessed in dental casts. Intergroup angulations and eruption status comparisons were performed using one-way analysis of variance (ANOVA), followed by Tukey's test and Kruskal-Wallis test, respectively.

Results

Significantly greater mesial angulation and percentage of erupted right maxillary third molars were observed in the Class I extraction group. Significantly greater eruption status of the right mandibular third molars was observed in the Class I and Class II malocclusion extraction groups.

Conclusion

Class I and II malocclusion extraction treatment exhibited more favorable angulations and a greater number of erupted third molars than non-extraction treatment. The non-extraction groups exhibited a greater percentage of unerupted third molars.

TMEM119 (c.G143A, p.S48L) Mutation Is Involved in Primary Failure of Eruption by Attenuating Glycolysis-Mediated Osteogenesis

Primary failure of eruption (PFE) is a rare oral disease with an incidence rate of 0.06%. It is characterized by abnormal eruption mechanisms that disrupt tooth eruption. The underlying pathogenic genetic variant and mechanism of PFE remain largely unknown. The purpose of this study was to explore the role of a novel transmembrane protein 119 (TMEM119) mutation in two PFE patients in a Chinese family. Information collection was performed on the family with a diagnosis of PFE, and blood samples from patients and healthy family members were extracted. Whole-exome sequencing was performed. Bioinformatics analysis revealed that a heterozygous variant in the TMEM119 gene (c.G143A, p.S48L) was a disease-associated mutation in this family. Recombinant pcDNA3.1 plasmid-containing wild-type and mutant TMEM119 expression cassettes were successfully constructed and transfected into MC3T3-E1 cells, respectively. The results of in vitro analysis suggested that the subcellular distribution of the TMEM119 protein was transferred from the cell cytoplasm to the nucleus, and the ability of cells to proliferate and migrate as well as glycolytic and mineralized capacities were reduced after mutation. Furthermore, rescue assays showed that activating transcription factor 4 (ATF4) overexpression rescued the attenuated glycolysis and mineralization ability of cells. Results of in vivo analysis demonstrated that TMEM119 was mainly expressed in the alveolar bone around the mouse molar germs, and the expression level increased with tooth eruption, demonstrated using immunohistochemistry and immunofluorescence. Collectively, the novel TMEM119 mutation is potentially pathogenic in the PFE family by affecting the glucose metabolism and mineralized function of osteoblasts, including interaction with ATF4. Our findings broaden the gene mutation spectrum of PFE and further elucidate the pathogenic mechanism of PFE.

Over-eruption in marsupial carnivore teeth: compensation for a constraint

Pronounced over-eruption of the canine teeth, causing the cervical enamel margin to extend beyond the alveolar bone and exposing the root, occurs with age and growth in Australian marsupial carnivores, much more than in eco-morphologically equivalent placental carnivores. Suppression of functional tooth replacement is characteristic of marsupials, where most placentals have the primitive diphyodont pattern of two generations of incisor, canine and premolar teeth. Canine and molar tooth dimensions of four species of marsupial carnivores (thylacine Thylacinus cynocephalus, Tasmanian devil Sarcophilus harrisii and two quolls Dasyurus spp.) and canine dimensions of seven eco-morphologically equivalent placental carnivore species were measured from museum specimens. Canine dimensions were measured in a time series on live wild-living individual devils and quolls. The canine teeth and to a lesser extent the molar teeth of marsupial carnivores continue to erupt through life, resulting in a net increase in tooth height and diameter, a phenomenon not evident in placental carnivores. Potential mechanisms causing over-eruption include tooth wear and gradual release of occlusal pressure as the individual grows. Over-eruption in marsupial carnivores may be a compensatory response for tooth size limits imposed by monophyodont tooth replacement, ensuring that animal's teeth are scaled to jaw size from juvenile to adulthood.

Effects of antiresorptive medications on tooth root formation and tooth eruption in paediatric patients

Tooth eruption is a pivotal milestone for children's growth and development. This process involves with the formation of the tooth root, the periodontal ligament (PDL) and the alveolar bone, as the tooth crown penetrates the bone and gingiva to enter the oral cavity. This review aims to outline current knowledge of the adverse dental effects of antiresorptive medications. Recently, paediatric indications for antiresorptive medications, such as bisphosphonates (BPs), have emerged, and these agents are increasingly used in children and adolescents to cure pathological bone resorption associated with bone diseases and cancers. Since tooth eruption is accompanied by osteoclastic bone resorption, it is expected that the administration of antiresorptive medications during this period affects tooth development. Indeed, several articles studying human patient cohorts and animal models report the dental defects associated with the use of these antiresorptive medications. This review shows the summary of the possible factors related to tooth eruption and introduces the future research direction to understand the mechanisms underlying the dental defects caused by antiresorptive medications.

Mandibular second premolar distoangulation: a longitudinal follow-up from the mixed to the permanent dentition

OBJECTIVE

The aim of this study was to assess the frequency of mandibular second premolar (MnP2) distoangulation among orthodontic patients and the angular changes after a longitudinal follow-up.

METHODS

The sample was collected from the orthodontic records of 865 patients. The distoangulation group was composed of 42 patients (mean age 9.29 ± 1.24 years, 16 male, 26 female) with distoangulation of MnP2. The control group was composed of 32 patients (mean age 9.38 ± 1.10 years, 15 male, and 17 female) without distoangulation of MnP2. Panoramic radiographs taken in the mixed (T1) and the early permanent dentition (T2) were analyzed in both groups. Longitudinal angular changes (distal angle θ and premolar-molar angle γ), degree of root formation, second premolar depth, and prevalence of associated dental anomalies were analyzed. Intergroup comparison was performed with Mann-Whitney, t-tests, and chi-square tests (P < 0.05).

RESULTS

The prevalence of MnP2 distoangulation in the mixed dentition was 4.85%. The distoangulation group showed a smaller initial distal angle (59.34o ± 8.41) when compared to control group (79.88o ± 7.60). The spontaneous eruption of the MnP2 with distoangulation was observed in 76.57% of the sample. MnP2 distoangulation was significantly associated with agenesis of its antimere, small maxillary lateral incisors, and deciduous molar infraocclusion.

LIMITATIONS

Severe cases of MnP2 distoangulation were absent in this study.

CONCLUSIONS

The frequency of MnP2 distoangulation among orthodontic patients was 4.85%. Mild to moderate distoangulated Mnp2 spontaneously uprighted from the mixed to the permanent dentition. Small lateral incisors, second premolar agenesis, and infraocclusion of deciduous molar were frequently found in cases with MnP2 distoangulation.

Timing of Primary Tooth Eruption in Infants Observed by Their Parents

BACKGROUND

The timing of primary teeth eruption is a visible indicator of infant physical growth other than body weight or height. It also reflects neurological integrity and development as well as nutrition, socioeconomic state, or underlying diseases. Therefore, the timing of primary teeth eruption is one of the major concerns for parents in health checkups for infants and children. However, the detailed developmental timing of teeth eruption differs depending on the survey methodology, country, or generation. We hypothesized that the timing of primary teeth eruption differs between the medical checkup by dentists and the daily records by parents.

METHODS

We conducted a questionnaire survey on the date of eruption of primary teeth as an adjunct study among Miyagi Regional Center participants in the Japan Environment and Children's Study (JECS), a large-scale birth cohort study. A total of 1695 responses (3793 participants) were analyzed.

RESULTS

The median ages of eruption were 7.1 months (male) and 7.6 months (female) for mandibular primary central incisors, 8.7 months (male) and 9.2 months (female) for maxillary primary central incisors, 10.0 months (male) and 10.3 months (female) for maxillary primary lateral incisors, and 10.4 months (male) and 10.8 months (female) for mandibular primary lateral incisors, which were earlier than the reported timings based on dental check-ups. Comparing the eruption time of preterm and term infants, the eruption time was earlier in preterm infants in the corrected ages.

CONCLUSIONS

The eruption timing observed and described by the parents is earlier than that examined by dentists at regular check-ups. In addition to examining the primary teeth eruption of full-term birth children, we also examined that of preterm birth children because of the increasing number of premature births. To the best of our knowledge, this is the first report from a large cohort study to clarify the eruption time of primary teeth monitored by parents.

The role of the endocannabinoid system in tooth eruption: An ex vivo study

The aim was to characterise the endocannabinoid system (ECS) in the dental pulp of teeth at different stages of eruption. Pulp of: erupted premolars (EPM), third molars in pre-eruptive (PThM), intraosseous (IThM) and eruptive stages (EThM) (n = 12 each group) were used. Messenger RNA expression of components of the ECS as cannabinoid receptors (CBr1 and CBr2), and anandamide synthetizing (NAPE-PLD) and degradation (FAAH) enzymes were measured by RT-PCR. Data were analysed using Student's t-test for comparisons between two groups and one-way analysis of variance and Tukey's post-test for multiple comparisons (statistical significance: p < 0.05). mRNA expression of CBr2, NAPE-PLD and FAAH was similar in the studied stages, was lower in IThM than in PThM and EThM, and the lowest in EThM (p < 0.01); of note, CBr2 mRNA expression was not detected in EThM. CBr1 mRNA did not differ significantly between IThM and PThM but was lower in EThM (p < 0.01). The absence of CBr2 and presence of CBr1 in EThM suggest the involvement of the ECS via CBr1 as a mediator of tooth and bone tissue homeostasis during tooth eruption.

Effect of periostin on bone metabolic and autophagy factors during tooth eruption in mice

This study aimed to investigate the effect of periostin (PN) on the expression of receptor activator of nuclear factor-κB ligand (RANKL), osteoprotegerin (OPG), microtubule-associated protein1 light chain 3B (LC3B), and Beclin1 in mouse alveolar bone specimens and cultured osteoblasts in vitro, to preliminarily explore the role of PN and autophagy in remodeling bone metabolism during tooth eruption. Mice at 5 days of age were injected with 75 ng/mL recombinant PN protein under the periosteum for 3 consecutive days according to the standard of 1 mL/100 g/day. Then, their mandibles were removed, and the expression of bone metabolic and autophagy factors was detected by immunohistochemistry. Mouse osteoblast-like cells cultured in vitro were treated with recombinant PN at a concentration of 75 ng/mL. The changes in the aforementioned indicators were compared again by immunofluorescence and western blotting 72 h after dosing. The results of the mouse samples showed that the protein expression of RANKL, LC3B, and Beclin1 decreased, accompanied by the decrease in RANKL/OPG ratio. However, OPG protein expression increased in the dosing group. Immunofluorescence and western blotting results of osteoblasts cultured in vitro showed that the protein expression of RANKL, LC3B, Beclin1, and the RANKL/OPG ratio in the experimental group decreased, but OPG expression increased. PN may regulate alveolar bone metabolism during tooth eruption by inhibiting the RANKL/OPG ratio and autophagy, which will provide a new research perspective for further exploration of the mechanisms during tooth eruption.

Genotype-phenotype analysis of selective failure of tooth eruption-A systematic review

Tooth eruption is an important and unique biological process during craniofacial development. Both the genetic and environmental factors can interfere with this process. Here we aimed to find the failure pattern of tooth eruption among five genetic diseases. Both systematic review and meta-analysis were used to identify the genotype-phenotype associations of unerupted teeth. The meta-analysis was based on the characteristics of abnormal tooth eruption in 223 patients with the mutations in PTH1R, RUNX2, COL1A1/2, CLCN7, and FAM20A respectively. We found all the patients presented selective failure of tooth eruption (SFTE). Primary failure of eruption patients with PTH1R mutations showed primary or isolated SFTE1 in the first and second molars (59.3% and 52% respectively). RUNX2 related cleidocranial dysplasia usually had SFTE2 in canines and premolars, while COL1A1/2 related osteogenesis imperfecta mostly caused SFTE3 in the maxillary second molars (22.9%). In CLCN7 related osteopetrosis, the second molars and mandibular first molars were the most affected. While FAM20A related enamel renal syndrome most caused SFTE5 in the second molars (86.2%) and maxillary canines. In conclusion, the SFTE was the common characteristics of most genetic diseases with abnormal isolated or syndromic tooth eruption. The selective pattern of unerupted teeth was gene-dependent. Here we recommend SFTE to classify those genetic unerupted teeth and guide for precise molecular diagnosis and treatment.

Eruption of Permanent Teeth As Risk Factor for Allergic Reactions During Oral Immunotherapy

Background: Oral immunotherapy (OIT) increases the threshold of reaction in children older than 4 years with food allergy. The risk for severe allergic reactions (ARs) during OIT has been reported in several studies, often in the presence of concomitant cofactors such as physical exercise, empty stomach, medications, poorly controlled asthma, menses, and alcohol consumption. Cases Presentation: We describe a case series of 5 scholar age patients undergoing OIT who showed ARs to a known, previously tolerated dose of allergen during permanent tooth eruption, in which other known cofactors were excluded. Conclusions: Patients may be exposed to cofactors due to behavioral habits not only in the second and third decades of life, but also in the first decade of life, due to the timing of mixed dentition. More studies are needed to estimate the frequency and entity of tooth eruption as cofactor, as well as to know the correct management of children undergoing dentition during OIT.

Salivary Protein and Electrolyte Profiles during Primary Teeth Eruption: A Cross-Sectional Study

This study aimed to assess the qualitative changes in the saliva during the process of primary teeth eruption. This cross-sectional study was conducted on 147 children from 2 to 48 months, of which 49 were in group A (no erupted primary teeth), 53 were in group B (at least one active erupting primary tooth), and 45 were in group C (eruption of all 20 primary teeth was completed). Salivary proteins were evaluated by sodium dodecyl sulfate electrophoresis with polyacrylamide gel, while the concentrations of salivary sodium, potassium, chloride, and calcium ions were evaluated by ion selective electrodes. The data were analyzed using ANOVA and Bonferroni tests (alpha = 0.05). The concentration of proteins with molecular weights of 20-30 KDa was significantly higher in group A, and it gradually decreased with age. The concentration of proteins with molecular weights of 50-60 KDa in group B was significantly lower than those of groups A and C. The calcium ion concentration in group A was significantly higher than that of the other groups. The concentration of potassium ions was minimal in group C. The proteins and electrolyte profiles of the subjects' saliva changed in the process of primary tooth eruption. The highest concentrations of proteins such as statherin, histatin, P-B peptide, and cystatin and the lowest concentrations of proteins such as amylase were present in group B.

Comparison of the opinions and attitudes of medical doctors, dentists and mothers toward teething symptoms

BACKGROUND

The signs and symptoms associated with teething can be local or systemic. It remains unclear whether the disturbances are caused by the eruption of primary teeth or whether they simply coincide with tooth eruption. Parents and healthcare professionals can have different perceptions about teething symptoms, especially in different cultural or socio-economic contexts.

OBJECTIVES

The study aimed to compare the opinions and attitudes of medical doctors, dentists and mothers toward the symptoms of teething.

MATERIAL AND METHODS

Data about the signs and symptoms was collected using a researcher-made questionnaire. The questionnaire was mailed in December 2019 to 800 randomly selected medical doctors and dentists working in the Central Aegean Region of Turkey. Mothers of children aged 0-3 years who were referred to the pediatric department were selected for the study. Data from 199 medical doctors (109 family physicians, 90 pediatricians), 293 dentists (169 general dentists, 124 pediatric dentists) and 352 mothers who completed the questionnaire was included in the study. The data was analyzed using the IBM SPSS Statistics for Windows program.

RESULTS

Each participant identified at least one symptom related to teething. Statistically significant differences were found between the 3 groups in terms of symptoms except for stomach ache (p < 0.05). Gingival irritation was the most common symptom among dentists (95.6%) and mothers (70.7%), while irritability was the most common symptom among medical doctors (90.5%). Mothers believed to a greater extent than the other groups that fever, vomiting and cough were associated with teething (p < 0.05), whereas medical doctors tended to point to drooling, irritability, biting/chewing, diarrhea, and ear rubbing more often than the other groups (p < 0.05). In addition, sleep disturbance and loss of appetite were associated with teething less frequently by mothers as compared to the other groups (p < 0.05).

CONCLUSIONS

In the present study, medical doctors, dentists and mothers reported unproven and controversial associations between teething and certain local or systemic symptoms. Mothers especially were more likely to believe that systemic symptoms that can be confused with other serious diseases were associated with teething.

Novel Genetic Determinants of Dental Maturation in Children

Dental occlusion requires harmonious development of teeth, jaws, and other elements of the craniofacial complex, which are regulated by environmental and genetic factors. We performed the first genome-wide association study (GWAS) on dental development (DD) using the Demirjian radiographic method. Radiographic assessments from participants of the Generation R Study (primary study population, N1 = 2,793; mean age of 9.8 y) were correlated with ~30 million genetic variants while adjusting for age, sex, and genomic principal components (proxy for population stratification). Variants associated with DD at genome-wide significant level (P < 5 × 10-8) mapped to 16q12.2 (IRX5) (lead variant rs3922616, B = 0.16; P = 2.2 × 10-8). We used Fisher's combined probability tests weighted by sample size to perform a meta-analysis (N = 14,805) combining radiographic DD at a mean age of 9.8 y from Generation R with data from a previous GWAS (N2 = 12,012) on number of teeth (NT) in infants used as proxy of DD at a mean age of 9.8 y (including the ALSPAC and NFBC1966). This GWAS meta-analysis revealed 3 novel loci mapping to 7p15.3 (IGF2BP3: P = 3.2 × 10-8), 14q13.3 (PAX9: P = 1.9 × 10-8), and 16q12.2 (IRX5: P = 1.2 × 10-9) and validated 8 previously reported NT loci. A polygenic allele score constructed from these 11 loci was associated with radiographic DD in an independent Generation R set of children (N = 703; B = 0.05, P = 0.004). Furthermore, profiling of the identified genes across an atlas of murine and human stem cells observed expression in the cells involved in the formation of bone and/or dental tissues (>0.3 frequency per kilobase of transcript per million mapped reads), likely reflecting functional specialization. Our findings provide biological insight into the polygenic architecture of the pediatric dental maturation process.

Exposure of suckling rats to hexavalent chromium (CrVI) alters bone formation at the base of the alveolus causing a delay in tooth eruption

OBJECTIVES

Hexavalent chromium (CrVI)-exposure of suckling rats has been shown to delay tooth eruption. However, the effects of CrVI-exposure on bone formation at the base of the alveolus, which provides a motive force for tooth eruption in the early stages of the process, remain unknown. The present work sought to evaluate the effect of CrVI-exposure on bone formation at the base of the alveolus during the intraosseous stage of tooth eruption in suckling rats, using histomorphometric and immunohistochemical studies.

METHODS

Experimental animals received 12.5 mg/kg-bw/day of potassium dichromate dissolved in saline solution by gavage starting on day 4 of the experiment; controls similarly received an equivalent volume of saline. All the animals were euthanized at the age of 9 days. The base of the developing alveolus at the level of the mesial root of the first lower molar was analyzed histomorphometrically and immunohistochemically. Data were statistically analyzed using student's t-test, with statistical significance set at p <0.05.

RESULTS

CrVI-exposed animals showed lower bone volume and height at the base of the alveolus, a significant preponderance of bone rest on the surface adjacent to the dental follicle, and a significantly lower percentage of positive Runt-related transcription factor-2 (RUNX2+) osteoblasts and a significantly higher number of mesenchymal-like RUNX2+ cells at the latter site.

CONCLUSION

CrVI-exposure during lactation affects bone formation at the base of the developing alveolus, delaying tooth eruption. These findings underscore the importance of controlling drinking water levels of toxic substances since their effects can alter the growth and development of individuals exposed during early childhood.

Mechanisms during Osteogenic Differentiation in Human Dental Follicle Cells

Human dental follicle cells (DFCs) as periodontal progenitor cells are used for studies and research in regenerative medicine and not only in dentistry. Even if innovative regenerative therapies in medicine are often considered the main research area for dental stem cells, these cells are also very useful in basic research and here, for example, for the elucidation of molecular processes in the differentiation into mineralizing cells. This article summarizes the molecular mechanisms driving osteogenic differentiation of DFCs. The positive feedback loop of bone morphogenetic protein (BMP) 2 and homeobox protein DLX3 and a signaling pathway associated with protein kinase B (AKT) and protein kinase C (PKC) are presented and further insights related to other signaling pathways such as the WNT signaling pathway are explained. Subsequently, some works are presented that have investigated epigenetic modifications and non-coding ncRNAs and their connection with the osteogenic differentiation of DFCs. In addition, studies are presented that have shown the influence of extracellular matrix molecules or fundamental biological processes such as cellular senescence on osteogenic differentiation. The putative role of factors associated with inflammatory processes, such as interleukin 8, in osteogenic differentiation is also briefly discussed. This article summarizes the most important insights into the mechanisms of osteogenic differentiation in DFCs and is intended to be a small help in the direction of new research projects in this area.

Is the third molar erupting at a younger age than before?

OBJECTIVES

The aim of this study was to update the much-cited knowledge, published over half a century ago, of the age of eruption of the third molar in the Finnish population.

METHODS

The study followed a retrospective and cross-sectional protocol and included 710 digital panoramic radiographs of patients (49.3% men, 50.7% women) aged 15-23 years visiting the public oral health care services of the City of Helsinki in 2015. Age and sex of the subjects were recorded. The radiographs were examined for inclination of the third molars in both jaws and vertically located teeth were further classified into four stages of eruption: (A) in bone, (B) alveolar emergence, (C) gingival emergence, and (D) complete emergence. Statistics included chi-squared, Mann-Whitney U, and median tests.

RESULTS

Of altogether 2502 third molars, 53.0% (n = 1325) were in vertical position. The median age of gingival emergence (stage C) of the third molar varied between 19.8 and 20.8 years, and the median age of reaching the occlusal level (stage D) between 20.8 and 21.8 years depending on sex and the jaw.

CONCLUSION

The median ages for the third molar to pierce the gum were lower than reported over half a century ago.

Expanding genotypic and phenotypic spectrums of LTBP3 variants in dental anomalies and short stature syndrome

Mutations in LTBP3 are associated with Dental Anomalies and Short Stature syndrome (DASS; MIM 601216), which is characterized by hypoplastic type amelogenesis imperfecta, hypodontia, underdeveloped maxilla, short stature, brachyolmia, aneurysm and dissection of the thoracic aorta. Here we report a novel (p.Arg545ProfsTer22) and a recurrent (c.3107-2A > G) LTBP3 variants, in a Turkish family affected with DASS. The proband, who carried compound heterozygous variant c.3107-2A > G, p.Arg545ProfsTer22, was most severely affected with DASS. The proband's father, who carried the heterozygous variant c.3107-2A > G had short stature and prognathic mandible. The mother and brother of the proband carried the heterozygous variant p.Arg545ProfsTer22, but only the mother showed any DASS characteristics. The c.3107-2A > G and the p.Arg545ProfsTer22 variants are expected to result in abnormal LTPB3 protein, failure of TGFβ-LAP-LTBP3 complex formation, and subsequent disruption of TGFβ secretion and activation. This is the first report of heterozygous carriers of LTBP3 variants showing phenotypes. The new findings of DASS found in this family include taurodontism, single-rooted molars, abnormal dentin, calcified dental pulp blood vessels, prognathic mandible, failure of mandibular tooth eruption, interatrial septal aneurysm, secundum atrial septal defect, tricuspid valve prolapse, and a recurrent glenohumeral joint dislocation.

Dental Abnormalities in Immature Dogs with a History of Mandibular Fractures

This study was performed to report the dental abnormalities encountered in immature dogs with a history of mandibular fracture. Dogs were included in the study if mandibular fractures were diagnosed by means of oral examination and diagnostic imaging, they were treated with non-invasive or minimally invasive methods, and there was a follow-up examination of at least 90 days after the initial presentation with the last follow-up visit occurring at 6 months of age or older. Eleven dogs met the inclusion criteria. Dental abnormalities occurred exclusively in those dogs that had sustained fracture of the mandibular body or fracture at the transition of mandibular body and mandibular ramus. A high number of developing permanent teeth located in or near the mandibular fracture were affected (73.5%). The most common dental abnormalities were failure of eruption or partial eruption (29.0%), resorption (22.6%), abnormal shape (19.4%), and enamel hypoplasia (16.1%). The majority of deciduous teeth (64.3%) in or near the mandibular fracture exfoliated uneventfully. Ten out of 11 dogs needed a surgical procedure to treat dental abnormalities after mandibular fracture healing. The development of the tooth germs located in or near a mandibular fracture is frequently affected. Radiographic evaluation of the area of trauma is recommended until eruption and full development of the teeth are completed.

Unicystic ameloblastoma in a 9-year-old child treated with a combination of conservative surgery and orthodontic treatment: A case report

Unicystic ameloblastoma (UAM) in the pediatric population is a rare clinical entity that has not been well addressed in the literature. Radical approaches affect a growing young patient's physical and psychological development, so conservative approaches are widely used for management in children. This report describes the case of a 9-year-old girl with UAM of the mandible, which also involved the impaction of the first and second premolars. Marsupialization with orthodontic treatment was performed to shrink the lesion and upright the first premolar involved in the tumor. Ten months after marsupialization, the lesion had healed entirely. The combination of conservative surgery and orthodontic treatment effectively shrank the lesion, preserving mandibular growth, preserving the involved first and second premolars, and promoting the eruption of the teeth.

Does molar-incisor hypomineralization (MIH) affect only permanent first molars and incisors? New observations on permanent second molars

BACKGROUND

The second permanent molar plays an important role when considering extraction of first permanent molars severely affected by molar-incisor hypomineralization (MIH).

AIM

To assess the association between MIH and enamel hypomineralization of the second permanent molars in terms of presence and severity.

DESIGN

In this retrospective cross-sectional study, permanent teeth were evaluated in 453 patients between the ages of 13 and 16 at a dental clinic, using intraoral photographs. A calibrated examiner classified enamel hypomineralization using the MIH index and dental caries experience using the DMFT and DMFS indices. Statistical analyses were performed using a linear generalized model and ordinal logistic regression.

RESULTS

The most commonly affected teeth by enamel hypomineralization were permanent molars, whereas incisors, premolars, and canines were less affected. The presence of severe defects in the first permanent molars was associated with mild defects in the second permanent molars (OR = 4.01; 95% CI: 2.50-7.77). Enamel hypomineralization was associated with increased caries experience (PR = 5.54; 95% CI: 3.81-9.06).

CONCLUSION

Enamel hypomineralization mainly affects the first and second permanent molars. Mild defects in the second permanent molars tend to be more frequent in patients with severe MIH in the first permanent molars. The presence of enamel hypomineralization was associated with higher dental caries experience.

Oral manifestations of congenital Zika virus infection in children with microcephaly: 18-month follow-up case series

AIMS

To describe oral manifestations in children born with microcephaly attributed to congenital Zika virus syndrome (CZS).

METHODS

Data was collected in semiannual intervals from 2017 to 2019, by oral exams of the children and interview with caregivers at a Public Dental Center in Rio de Janeiro, Brazil. A single calibrated examiner performed clinical examinations.

RESULTS

Of 38 eligible children, 34 were followed-up from 12 to 30 months of age, 20 boys and 14 girls. The mean age of emergence of their first primary tooth was 12.4 months (SD = 2.9). By 30 months of age only 14.7% (n = 5) had complete primary dentition. Alteration in the sequence of tooth emergence was observed in 41.1% (n = 14). Radiographic examination demonstrated dental agenesis (14.7% n = 5). Dental developmental alterations (38.2%, n = 13), enamel defects (14.7%, n = 5), eruption cysts/hematoma (23.5%, n = 8), gingival bleeding (55.8%, n = 19), narrow palate, and bruxism (64.7%, n = 22) were also observed. No child had dental caries.

CONCLUSION

Children with microcephaly attributed to CZS presented oral manifestations early in life.

The Role of Wnt Signaling in Postnatal Tooth Root Development

Appropriate tooth root formation and tooth eruption are critical for achieving and maintaining good oral health and quality of life. Tooth eruption is the process through which teeth emerge from their intraosseous position to their functional position in the oral cavity. This temporospatial process occurs simultaneously with tooth root formation through a cascade of interactions between the epithelial and adjoining mesenchymal cells. Here, we will review the role of the Wnt system in postnatal tooth root development. This signaling pathway orchestrates the process of tooth root formation and tooth eruption in conjunction with several other major signaling pathways. The Wnt signaling pathway is comprised of the canonical, or Wnt/β-catenin, and the non-Canonical signaling pathway. The expression of multiple Wnt ligands and their downstream transcription factors including β-catenin is found in the cells in the epithelia and mesenchyme starting from the initiation stage of tooth development. The inhibition of canonical Wnt signaling in an early stage arrests odontogenesis. Wnt transcription factors continue to be present in dental follicle cells, the progenitor cells responsible for differentiation into cells constituting the tooth root and the periodontal tissue apparatus. This expression occurs concurrently with osteogenesis and cementogenesis. The conditional ablation of β-catenin in osteoblast and odontoblast causes the malformation of the root dentin and cementum. On the contrary, the overexpression of β-catenin led to shorter molar roots with thin and hypo-mineralized dentin, along with the failure of tooth eruption. Therefore, the proper expression of Wnt signaling during dental development is crucial for regulating the proliferation, differentiation, as well as epithelial-mesenchymal interaction essential for tooth root formation and tooth eruption.

Vitamin D deficiency is a risk factor for delayed tooth eruption associated with persistent primary tooth

OBJECTIVE

To verify the association between 25(OH)D level and polymorphisms in the vitamin D receptor gene (VDR) with the disturbance in the dental development and eruption.

DESIGN

A total of 183 children from two datasets were evaluated. The first dataset was a case-control (15:15) designed to assess if persistent primary tooth (PPT) is associate with serum 25(OH)D level and with genetic polymorphisms in VDR. The second dataset of genomic DNA samples from 54 children with delayed tooth eruption (DTE) and 99 controls were analysed to verify if genetic polymorphisms in VDR (rs2228570 and rs739837) are associated with DTE. The 25(OH)D and the genotyping/allele distribution were analysed using the T-test and chi-square test, respectively.

RESULTS

The level of 25(OH)D in the PPT group (24.9 ± 6.4 mg/mL) was significantly lower than the control (30.0 ± 7.0 mg/mL) (p=.047). Our data show that children with 25(OH)D deficiency are more likely to present PPT (OR = 2.36; 95%CI: 1.51, 3.70). The rs739837 and rs2228570 polymorphisms were not associated with DTE (OR = 1.44; 95%CI: 0.87, 2.39 and OR = 0.80; 95%CI: 0.45, 1.44, respectively).

CONCLUSIONS

Vitamin D deficiency is a risk factor for PPT.

Hexavalent chromium exposure alters bone remodeling in the developing tooth alveolus and delays tooth eruption

Although it has been demonstrated that exposure of lactating rats to CrVI delays tooth eruption, the effects of CrVI exposure on bone remodeling in the developing alveolus during tooth eruption remain unknown. Our purpose was to analyze the effect of CrVI in the alveolus of the first lower molar of rats. Thirty-two suckling Wistar rats were divided into two groups. The experimental group received 12.5 mg/kg body weight/day of potassium dichromate dissolved in saline solution by oral gavage as of day 4 of the experiment; the control group received an equal dose of saline solution. Each group was divided into two sub-sets and euthanized at the ages of 9 and 15 days, respectively. Histochemical and histomorphometric studies of the bone surfaces of the developing tooth alveolus were performed. The percentage of bone formation surfaces was lower in experimental animals than in age-matched controls. The percentage of bone resorption surfaces was significantly lower in 9-day-old experimental rats than in controls and significantly higher in 15-day-old experimental rats than in controls. Exposure to CrVI during lactation alters the sequence of bone resorption and formation in the walls of the developing alveolus, both of which are necessary for tooth eruption, thus causing a delay.

Revisiting the human dental follicle: From tooth development to its association with unerupted or impacted teeth and pathological changes

Dental follicles are involved in odontogenesis, periodontogenesis, and tooth eruption. Dental follicles are unique structures, considering that their remnants can persist within the jawbones after odontogenesis throughout life if the tooth does not erupt. Pathological changes may occur in these tissues as individuals age. The changes range from benign to life threatening. Thus, the assessment of age-related changes in dental follicles associated with unerupted teeth is of paramount importance. In this review, we summarize the physiological roles and changes in dental follicles in odontogenesis, tooth eruption, and aging, in addition to the pathological changes associated with these structures. We encourage investigators to consider this peculiar tissue as a unique model and explore its potential to clarify its importance from the viewpoints of developmental biology, tissue physiology, and pathology.

Nutritional Status is Associated with Permanent Tooth Eruption in a Group of Brazilian School Children

The present study aimed to investigate the association between nutritional status with delayed tooth eruption (DTE). Oral examination was performed in schoolchildren (8-11 years old), and DTE was defined by absence of dental gingival emergence or when primary tooth was still present in the oral cavity after the expected time. BMI z-score of each child were collected and nutritional status was defined. Chi-square test and binary logistic regression adjusted by age and gender were performed. Odds ratio (OR) and 95% Confidence Interval (95% CI) were calculated. The established alpha was 5%. Among 353 included children, 247 were classified as eutrophic, 16 as underweight, 64 as overweight, and 26 as obese. Underweight was associated as a risk factor to DTE (P = .014; OR = 3.5; 95% CI = 1.3-9.8), and underweight girls had more chance to present DTE than eutrophic girls (P = .048; OR = 4.4; 95% CI = 1.1-17.2) in chi square test. In logistic regression, underweight was associated as a risk factor to DTE (OR = 4.21; CI 95% = 1.42-12.43; P = .009). Underweight children have a higher risk of DTE in permanents.

Tooth Eruption and Early Childhood Caries: A Multisite Longitudinal Study

Purpose: The purpose of this study was to assess the relationship between the number of teeth present at 12 months and decayed, missing, or filled surfaces (dmfs) at 30 and 48 months. Methods: Data are from a longitudinal, multisite study with clinical dental examinations conducted at 12, 30, and 48 months of age. Spearman correlation and chi-square tests assessed relationships between teeth present at 12 months and dmfs at 30 (n equals 1,062) and 48 months (n equals 985). Results: Spearman correlations were weak but significant for both 30- and 48-month time points (R equals 0.066, P=0.032; R equals 0.093, P=0.004, respectively). Mantel-Haenszel chi-square analyses of categories of teeth present at 12 months (zero, one to four, five to eight, and greater than or equal to nine) and categories of dmfs at 30 and 48 months (zero, one to two, three to five, six to 15, and greater than or equal to 16) revealed nonsignificant (P=0.326) relationship with 30-month dmfs but a significant (P=0.013) relationship with 48-month dmfs. Conclusion: Results suggest that early tooth eruption is weakly associated with an occurrence of early childhood caries.

Ectopic Eruption of Maxillary First Permanent Molars: Preliminary Results of Prevalence and Dentoskeletal Characteristics in Spanish Paediatric Population

The ectopic eruption of the maxillary first permanent molar (EEM) is a local alteration of dental eruption with a multifactorial aetiology. The aims of our study were to determine the prevalence of the EEM in children and to analyse whether there is a relationship between EEM and dento-skeletal characteristics. A total of 322 children were analysed with the Ricketts cephalometric study and descriptive and analytical statistical analysis was carried out. The prevalence of EEM was 8.7%, with no statistically significant differences regarding gender or location, but a higher prevalence in the 7-year-old age group (18.8%) and bilateral EEM was more prevalent than unilateral EEM (p < 0.05). The most frequent findings were a shortened anterior cranial base, a retroposition of the maxilla and a distal position of the upper permanent first molar in relation to the pterygoid vertical in children with EEM. No statistically significant differences were found regarding the cephalometric parameters except a decreased palatal plane in the bilateral EEM group and a distal upper incisor position in the EEM group (p < 0.05). In conclusion, the prevalence of the EEM was 8.7%, more frequently bilateral, and significantly in seven-year-old patients. Children with bilateral EEM have decreased palatal plane values and a more posterior position of the upper incisor.

Evaluation of Vitamin D (25OHD), Bone Alkaline Phosphatase (BALP), Serum Calcium, Serum Phosphorus, Ionized Calcium in Patients with Mandibular Third Molar Impaction. An Observational Study

The aim of this study was to evaluate the levels of vitamin D (25OHD) and other bone biomarkers in patients with third molar impaction (TMI). Thirty males and 30 females with unilateral or bilateral impacted mandibular third molar, and 15 males and 15 females as a control group (CG) were recruited. Rx-OPT was used to evaluate dental position and Pederson index to measure the difficulty of the intervention. Bone biomarkers were measured through blood venous sample in TMI group and CG. Mann-Whitney test, Pearson’s correlation coefficient, linear regression model were used to compare the different parameters in the two groups. 25OHD showed lower values in TMI group than in CG (p < 0.05) with values significantly lower in bilateral impaction (p < 0.05). Pearson’s coefficient for 25OHD presented a negative correlation with the Pederson index (ρ = −0.75). Bone alkaline phosphatase (BALP) showed significantly lower dosage in TMI group than CG (p = 0.02), Pearson’s coefficient for BALP presented a negative correlation with the Pederson index. Serum calcium, serum phosphorus, ionized calcium levels in TMI and CG groups were similar and Mann-Whitney test did not significantly differ between TMI and CG. TMI could be a sign of vitamin D deficiency and of low BALP levels that should be investigated.

Cementocyte alterations associated with experimentally induced cellular cementum apposition in hyp mice

BACKGROUND

Cellular cementum, a mineralized tissue covering apical tooth roots, grows by apposition to maintain the tooth in its occlusal position. We hypothesized that resident cementocytes would show morphological changes in response to cementum apposition, possibly implicating a role in cementum biology.

METHODS

Mandibular first molars were induced to super-erupt (EIA) by extraction of maxillary molars, promoting rapid new cementum formation. Tissue and cell responses were analyzed at 6 and/or 21 days post-procedure (dpp).

RESULTS

High-resolution micro-computed tomography (micro-CT) and confocal laser scanning microscopy showed increased cellular cementum by 21 dpp. Transmission electron microscopy (TEM) revealed that cementocytes under EIA were 50% larger than control cells, supported by larger pore sizes detected by micro-CT. Cementocytes under EIA displayed ultrastructural changes consistent with increased activity, including increased cytoplasm and nuclear size. We applied EIA to Hyp mutant mice, where cementocytes have perilacunar hypomineralization defects, to test cell and tissue responses in an altered mechanoresponsive milieu. Hyp and WT molars displayed similar super-eruption, with Hyp molars exhibiting 28% increased cellular cementum area versus 22% in WT mice at 21 dpp. Compared to control, Hyp cementocytes featured well-defined, disperse euchromatin and a thick layer of peripherally condensed heterochromatin in nuclei, indicating cellular activity. Immunohistochemistry (IHC) for cementum markers revealed intense dentin matrix protein-1 expression and abnormal osteopontin deposition in Hyp mice. Both WT and Hyp cementocytes expressed gap junction protein, connexin 43.

CONCLUSION

This study provides new insights into the EIA model and cementocyte activity in association with new cementum formation.

Eruption of Bioengineered Teeth: A New Approach Based on a Polycaprolactone Biomembrane

Obtaining a functional tooth is the ultimate goal of tooth engineering. However, the implantation of bioengineered teeth in the jawbone of adult animals never allows for spontaneous eruption due mainly to ankylosis within the bone crypt. The objective of this study was to develop an innovative approach allowing eruption of implanted bioengineered teeth through the isolation of the germ from the bone crypt using a polycaprolactone membrane (PCL). The germs of the first lower molars were harvested on the 14th day of embryonic development, cultured in vitro, and then implanted in the recipient site drilled in the maxillary bone of adult mice. To prevent the ankylosis of the dental germ, a PCL membrane synthesized by electrospinning was placed between the germ and the bone. After 10 weeks of follow-up, microtomography, and histology of the implantation site were performed. In control mice where germs were directly placed in contact with the bone, a spontaneous eruption of bioengineered teeth was only observed in 3.3% of the cases versus 19.2% in the test group where PCL biomembrane was used as a barrier (p < 0.1). This preliminary study is the first to describe an innovative method allowing the eruption of bioengineered tooth implanted directly in the jawbone of mice. This new approach is a hope for the field of tooth regeneration, especially in children with oligodontia in whom titanium implants are not an optimal solution.

Histologic Analysis of Clinically Healthy Human Gingiva in Patients with Altered Passive Eruption

The purpose of this study was to histologically examine the clinically healthy gingiva of patients with altered passive eruption (APE). Five patients with type 1 APE were enrolled. They underwent scaling and polishing and received oral hygiene instructions. After 6 months of supervised plaque control and uninterrupted gingival clinical health (Gingival Index (GI) = 0 and no Bleeding on Probing (BoP)), upper anterior teeth were surgically treated. During the surgical procedure, the excised gingival margin was collected to be histologically examined. In four out of five patients, signs of inflammation including spongiosis and neutrophil exocytosis could be found in the epithelium of the gingival sulcus. Ulceration with exposure of the lamina propria and inflammatory granulation tissue were evident in the most severe cases. Normal density and orientation of collagen fibers could be seen within the superficial and the deep portions of connective tissue, with an increase in size and number of the deep collagen fibers and a reduced laxity of the superficial ones. In conclusion, the clinically healthy gingiva of APE patients showed features compatible with persistent inflammation, possibly due to recurrent traumatisms caused by an incisally placed gingival margin.

Is Continuous Eruption Related to Periodontal Changes? A 16-Year Follow-up

The aims of this study were to 1) determine if continuous eruption occurs in the maxillary teeth, 2) assess the magnitude of the continuous eruption, and 3) evaluate the effects of continuous eruption on the different periodontal parameters by using data from the population-based cohort of the Study of Health in Pomerania (SHIP). The jaw casts of 140 participants from the baseline (SHIP-0) and 16-y follow-up (SHIP-3) were digitized as 3-dimensional models. Robust reference points were set to match the tooth eruption stage at SHIP-0 and SHIP-3. Reference points were set on the occlusal surface of the contralateral premolar and molar teeth, the palatal fossa of an incisor, and the rugae of the hard palate. Reference points were combined to represent 3 virtual occlusal planes. Continuous eruption was measured as the mean height difference between the 3 planes and rugae fix points at SHIP-0 and SHIP-3. Probing depth, clinical attachment levels, gingiva above the cementoenamel junction (gingival height), and number of missing teeth were clinically assessed in the maxilla. Changes in periodontal variables were regressed onto changes in continuous eruption after adjustment for age, sex, number of filled teeth, and education or tooth wear. Continuous tooth eruption >1 mm over the 16 y was found in 4 of 140 adults and averaged to 0.33 mm, equaling 0.021 mm/y. In the total sample, an increase in continuous eruption was significantly associated with decreases in mean gingival height (B = -0.34; 95% CI, -0.65 to -0.03). In a subsample of participants without tooth loss, continuous eruption was negatively associated with PD. This study confirmed that continuous eruption is clearly detectable and may contribute to lower gingival heights in the maxilla.

Comparison of information provided by pediatricians regarding tooth eruption and the information available on the internet

BACKGROUND

Most parents believe that teething is associated with some symptoms and commonly use Internet to gain more information about the health of their children. Pediatricians can also serve as a source of information for health-related requirements of parents. This study aimed to compare the information provided by pediatricians regarding tooth eruption and the information available in Persian-language websites.

MATERIALS AND METHODS

This descriptive, analytical, cross-sectional study was performed in two phases. In the first phase, the questionnaire was designed by 85 pediatric pediatricians in Isfahan about children's dental eruption and internet resources. The second phase was the study of 22 Persian websites about children's tooth eruption using Google search engine and the keywords "tooth eruption," "tooth eruption symptoms." Then a checklist was prepared to evaluate the quality and completeness of the content. Data were analyzed by the Chi-square test and Fisher's exact test using SPSS (P < 0.05).

RESULTS

None of the retrieved websites had the health on the net code of conduct. The most common symptoms of teething reported by both pediatricians and websites included irritability, drooling, gingival tenderness, chewing tendency, decreased appetite and sleep disturbances. In non-pharmacological methods to control the symptoms related to tooth eruption in both groups, embracing the baby (P < 0.001), using soft tooth ring (P = 0.049) and chewing hard foods (0.016 P = significant. Use of oral pain medication (P = 0.01) and sedatives and medications (P = 0.04) were significant in the medication method.

CONCLUSION

None of the websites reviewed had a valid source code and author. Although websites cannot replace the instructions of pediatricians regarding growth and development of children and their teething, supplementary information can be acquired from high-quality websites because there seems to be no significant difference between these two information sources regarding tooth eruption symptoms and their management.

Orofacial features in children with microcephaly associated with Zika virus: A scoping review

OBJECTIVE

To analyze published scientific evidence about the most common orofacial disorders in children with microcephaly associated with ZIKV infection.

METHODS

Through a scoping review, we respond to the search question was formulated: "What are the orofacial alterations in children with microcephaly associated with ZIKV?" It was performed a search in PubMed, EMBASE, Scopus, and Health Virtual Library. It was selected papers wrote in English, Portuguese, or Spanish. An evidence quality analysis was performed using the Agency for Healthcare Research and Quality classification.

RESULTS

It was included 11 studies performed in the Brazilian Northeast region. The studies were carried out between 2018 and 2020. The main related alterations were delay in the tooth-eruption and deformation in the oral structures.

CONCLUSION

The results observed in our work show moderate scientific evidence regarding the association of ZIKV with orofacial alterations in children with microcephaly due to the classifications of the quality of evidence of each one of the included studies. The main changes reported were in the chronology of tooth eruption, alteration in teeth, and oral structures.

Validation of a novel method for canine eruption assessment in unilateral cleft lip and palate patients

Objective

The aim of this study was to propose and validate a three‐dimensional (3D) methodology for the assessment of canine eruption in patients born with unilateral cleft lip and palate (UCLP) following secondary alveolar bone graft (SABG).

Methods and Materials

A total of 10 patients (four females, six males; mean age: 8.8 years) with UCLP who underwent SABG were recruited. Pre‐ and 6‐month post‐operative cone‐beam computed tomography (CBCT) was acquired for all patients. Post‐operative data was registered onto pre‐operative data utilizing voxel‐based registration. Following superimposition, a segmentation process was applied to segment maxillary canine on both cleft and non‐cleft side. Thereafter, translational and rotational changes in canine position were assessed for both cleft and non‐cleft side by two observers.

Results

The intra‐class correlation coefficient (ICC) indicated excellent reliability (≥0.90) with inter and intra‐observer error of less than 0.05 mm. The overall ICC was found to be high for assessing both translational and rotational changes. The mean absolute inter‐ and intra‐observer difference for translational and rotational changes was found to be less than 1 mm and 3°.

Conclusion

The present method was found to be reliable proving to be clinically applicable for assessing maxillary canine eruption changes in both cleft and non‐cleft bone.

Role of Innate Inflammation in the Regulation of Tissue Remodeling during Tooth Eruption

Tooth eruption is characterized by a coordinated complex cascade of cellular and molecular events that promote tooth movement through the eruptive pathway. During tooth eruption, the stratum intermedium structurally changes to the papillary layer with tooth organ development. We previously reported intercellular adhesion molecule-1 (ICAM-1) expression on the papillary layer, which is the origin of the ICAM-1-positive junctional epithelium. ICAM-1 expression is induced by proinflammatory cytokines, including interleukin-1 and tumor necrosis factor. Inflammatory reactions induce tissue degradation. Therefore, this study aimed to examine whether inflammatory reactions are involved in tooth eruption. Reverse transcription-polymerase chain reaction (RT-PCR) analysis revealed sequential expression of hypoxia-induced factor-1α, interleukin-1β, and chemotactic factors, including keratinocyte-derived chemokine (KC) and macrophage inflammatory protein-2 (MIP-2), during tooth eruption. Consistent with the RT-PCR results, immunohistochemical analysis revealed KC and MIP-2 expression in the papillary layer cells of the enamel organ from the ameloblast maturation stage. Moreover, there was massive macrophage and neutrophil infiltration in the connective tissue between the tooth organ and oral epithelium during tooth eruption. These findings suggest that inflammatory reactions might be involved in the degradation of tissue overlying the tooth organ. Further, these reactions might be induced by hypoxia in the tissue overlying the tooth organ, which results from decreased capillaries in the tissue. Our findings indicate that bacterial infections are not associated with the eruption process. Therefore, tooth eruption might be regulated by innate inflammatory mechanisms.

IL-1α Regulates Osteogenesis and Osteoclastic Activity of Dental Follicle Cells Through JNK and p38 MAPK Pathways

Inflammatory cytokines such as interleukin-1α (IL-1α) are increased in teeth with periapical lesions. Primary teeth with periapical lesions have a propensity for accelerated eruption of the successors. In this study, we asked whether increased levels of IL-1α in the dental follicle (DF) occurring as the result of periapical lesions promote tooth eruption, possibly due to enhanced osteoclastic remodeling of DF cells (DFCs). To this end, we studied the effect and possible mechanism of IL-1α on osteogenic differentiation, osteoclastogenic activity, and matrix remodeling of DFCs. Results demonstrated that DFCs cultured with IL-1α exhibited reduced osteogenic capacity, higher osteoclastogenic activity, and stronger invasive ability. Phosphorylation of JNK and p38 was upregulated, and pretreatment with SB203580 and SP600125 reversed the effect of IL-1α on DFCs. Neonatal rats subjected to subcutaneous injection of an IL-1 receptor antagonist exhibited a reduced number in activated osteoclasts, increased expression of alkaline phosphatase and osteopontin, and delayed tooth eruption. These data support our hypothesis that increased IL-1α cytokine levels as they occur during periodontal and periapical inflammation cause osteoclastic remodeling of the alveolar socket as a requirement for tooth eruption and thus may indirectly promote the vertical eruption of teeth toward the occlusal plane.

FAM83H and Autosomal Dominant Hypocalcified Amelogenesis Imperfecta

Autosomal dominant hypocalcified amelogenesis imperfecta (ADHCAI; OMIM #130900) is a genetic disorder exhibiting severe hardness defects and reduced fracture toughness of dental enamel. While the condition is nonsyndromic, it can be associated with other craniofacial anomalies, such as malocclusions and delayed or failed tooth eruption. Truncation mutations in FAM83H (OMIM *611927) are hitherto the sole cause of ADHCAI. With human genetic studies, Fam83h knockout and mutation-knock-in mouse models indicated that FAM83H does not serve a critical physiologic function during enamel formation and suggested a neomorphic mutation mechanism causing ADHCAI. The function of FAM83H remains obscure. FAM83H has been shown to interact with various isoforms of casein kinase 1 (CK1) and keratins and to mediate organization of keratin cytoskeletons and desmosomes. By considering FAM83H a scaffold protein to anchor CK1s, further molecular characterization of the protein could gain insight into its functions. In this study, we characterized 9 kindreds with ADHCAI and identified 3 novel FAM83H truncation mutations: p.His437*, p.Gln459*, and p.Glu610*. Some affected individuals exhibited hypoplastic phenotypes, in addition to the characteristic hypocalcification enamel defects, which have never been well documented. Failed eruption of canines or second molars in affected persons was observed in 4 of the families. The p.Glu610* mutation was located in a gap area (amino acids 470 to 625) within the zone of previously reported pathogenic variants (amino acids 287 to 694). In vitro pull-down studies with overexpressed FAM83H proteins in HEK293 cells demonstrated an interaction between FAM83H and SEC16A, a protein component of the COP II complex at endoplasmic reticulum exit sites. The interaction was mediated by the middle part (amino acids 287 to 657) of mouse FAM83H protein. Results of this study significantly extended the phenotypic and genotypic spectrums of FAM83H-associated ADHCAI and suggested a role for FAM83H in endoplasmic reticulum-to-Golgi vesicle trafficking and protein secretion (dbGaP phs001491.v1.p1).

Robust age estimation of southern sea otters from multiple morphometrics

Reliable age estimation is an essential tool to assess the status of wildlife populations and inform successful management. Aging methods, however, are often limited by too few data, skewed demographic representation, and by single or uncertain morphometric relationships. In this study, we synthesize age estimates in southern sea otters Enhydra lutris nereis from 761 individuals across 34 years of study, using multiple noninvasive techniques and capturing all life stages from 0 to 17 years of age. From wild, stranded, and captive individuals, we describe tooth eruptions, tooth wear, body length, nose scarring, and pelage coloration across ontogeny and fit sex-based growth functions to the data. Dental eruption schedules provided reliable and identifiable metrics spanning 0.3-9 months. Tooth wear was the most reliable predictor of age of individuals aged 1-15 years, which when combined with total length, explained >93% of observed age. Beyond age estimation, dental attrition also indicated the maximum lifespan of adult teeth is 13‒17 years, corresponding with previous estimates of life expectancy. Von Bertalanffy growth function model simulations of length at age gave consistent estimates of asymptotic lengths (male Loo  = 126.0‒126.8 cm, female Loo  = 115.3‒115.7 cm), biologically realistic gestation periods (t 0 = 115 days, SD = 10.2), and somatic growth (male k = 1.8, SD = 0.1; female k = 2.1, SD = 0.1). Though exploratory, we describe how field radiographic imaging of epiphyseal plate development or fusions may improve aging of immature sea otters. Together, our results highlight the value of integrating information from multiple and diverse datasets to help resolve conservation problems.

Greater caries-free survival of first permanent molars: Findings from a 7-year follow-up evaluation of a community-based oral health preventive program

BACKGROUND

The occlusal surface of the first permanent molar is the most frequently affected site by dental caries.

AIM

To assess the caries-free survival of first permanent molars in children participating in a community-based oral health preventive program.

DESIGN

This was a retrospective study conducted on 426 children under 12 years of age, beneficiaries of a preventive program from 2009 to 2015, in El Cedro, Colombia. The program offered oral health care education, supervised brushing and mouth washing, and application of topical fluoride. By using parametric survival models for interval-censored data, primary and secondary caries-free survival of any first permanent molar was estimated and analyzed.

RESULTS

Before program implementation, dental caries lesions presented at an average age, adjusted by age of eruption, of 8.3 years for primary caries lesion and 9.3 years for secondary caries lesion. After 7 years of the program, the estimated average age for presenting primary dental caries lesion was delayed by 4.6 years and by 5.3 years for secondary caries.

CONCLUSION

The implementation of the oral health program led to improved caries-free survival of first permanent molars.

Emergence stages of permanent teeth in twins: A comparative study

BACKGROUND

The relative effects of genetic factors on the timing of tooth eruption can be demonstrated through twin studies; however, twin studies on the eruption time of permanent teeth were limited.

AIM

To compare the emergence stages of permanent teeth in twins and non-twin children.

DESIGN

A total of 480 patients aged from 5.0 to 13.11 years who attended to the Department of Pediatric Dentistry for any dental reason were included in the study. Twins were compared with the control group in terms of the emergence stages for all permanent teeth.

RESULTS

At the age of 5 years, girls in the control group showed statistically significant differences related to the central incisors, the first molars in the mandibular dentition and the first molars in the maxillary dentition, showing more advanced emergence stages. In the 6- to 8- and 12- to 13-year-old age groups, no gender-related differences in emergence stages were observed. Gestation age was found to have a statistically significant effect on the emergence stages of permanent teeth. There were no statistically significant differences between birthweights and tooth emergence stages in twins.

CONCLUSION

Longitudinal studies are needed to determine whether there is a strong genetic effect on emergence stages of permanent teeth in twins.

Core Matrisome Protein Signature During Periodontal Ligament Maturation From Pre-occlusal Eruption to Occlusal Function

The pre-occlusal eruption brings the molars into functional occlusion and initiates tensional strains during mastication. We hypothesized that upon establishment of occlusal contact, the periodontal ligament (PDL) undergoes cell and extracellular matrix maturation to adapt to this mechanical function. The PDL of 12 Wistar male rats were laser microdissected to observe the proteomic changes between stages of pre-occlusal eruption, initial occlusal contact and 1-week after occlusion. The proteome was screened by mass spectrometry and confirmed by immunofluorescence. The PDL underwent maturation upon establishment of occlusion. Downregulation of alpha-fetoprotein stem cell marker and protein synthesis markers indicate cell differentiation. Upregulated proteins were components of the extracellular matrix (ECM) and were characterized with the matrisome project database. In particular, periostin, a major protein of the PDL, was induced following occlusal contact and localized around collagen α-1 (III) bundles. This co-localization coincided with organization of collagen fibers in direction of the occlusal forces. Establishment of occlusion coincides with cellular differentiation and the maturation of the PDL. Co-localization of periostin and collagen with subsequent fiber organization may help counteract tensional forces and reinforce the ECM structure. This may be a key mechanism of the PDL to adapt to occlusal forces and maintain structural integrity.

[Epidemiological rationale for community-based programs of caries prevention of permanent teeth for children of Samara city]

INTRODUCTION

The global objectives of WHO in the field of oral health by 2020 include the average intensity of caries among 12-year-old children no more than 1.5 by the DMFT index. In Samara the value of the DMFT among the adolescents at age 12 is 3.5.

AIM

To identify the appropriate timing for a launching of community-based schemes of dental caries prevention of permanent teeth for children of Samara.

MATERIAL AND METHODS

In a cross-sectoral multisample research from March to May 2017, the time of eruption and intensity of caries of the first permanent molars among children in Samara were studied. A total of 405 children aged 5 to 8, attending preschool and school educational institutions were examined. The quantity and the stage of eruption of the first permanent molars were assessed; the initial and manifest forms of caries were considered during the calculation of indexes of caries intensity of teeth and surfaces.

RESULTS

One to four first permanent molars were erupted among 26.3% of children aged 5, at an average 0.6±0.14 per one surveyed, the prevalence of caries of the first permanent molars was equal to 1.3%, including 1.3% of the initial carious defeats. In 6-year-old children - 65% had the first permanent molars, at an average of 2.38±0.199, and the prevalence of caries in these teeth was 29.63%, including initial forms of caries 27.16%. The results among 7-year-old children - 87.18% and 3.12±0.156, 60.3% and 51.28%, respectively. In 8-year-old children these figures were equal: 97.26%, 3.79±0.091, 68.49% and 60.27%, respectively. The rate of eruption of the first permanent molars and the prevalence of their carious lesions among girls was significantly higher than among boys.

CONCLUSION

The optimal age of children of Samara for inclusion in the regional programs of dental caries prevention is the age of 4 years - the age of the beginning of the first permanent molar eruption.

Alterations in odontogenesis and tooth eruption resulting from exposure to hexavalent chromium in suckling animals

BACKGROUND

Heavy metals including Cr VI are present in inadequately treated effluents that contaminate drinking water. Hence, Cr VI exposure can affect children through intake of breast milk from an exposed mother or bottle-feeding formula prepared with contaminated water. To date, there are no reports on the effects of Cr VI exposure on tooth formation processes concomitant to tooth eruption.

AIM

To study the effect of Cr VI exposure on tooth tissue formation in suckling Wistar rats by assessing dental tissues at different stages of tooth eruption.

DESIGN

Experimental animals received 12.5 mg/kg body weight/day of a potassium dichromate solution by gavage; control animals were similarly administered an equivalent volume of saline solution. Each group was divided into three subsets according to age at euthanasia: 9, 15, and 23 days. Dental formation was analysed histologically and histomorphometrically.

STATISTICAL ANALYSIS

Student's t test; P < .05.

RESULTS

Cr VI-exposed animals showed a delay in mineralized crown and root tissue formation. These findings are directly associated with the observed delay in tooth eruption.

CONCLUSION

Our findings show the importance of monitoring drinking water levels of toxic substances, since exposure during early childhood can alter tooth formation, growth, and development.

Experimental gingivitis in patients with and without altered passive eruption

BACKGROUND

Individuals with altered passive eruption (APE) are assumed to be more susceptible to periodontal diseases. To date, this hypothesis has not been sufficiently supported by scientific evidence. The aim of this study, using an experimental gingivitis model, was to examine the development and resolution of gingival inflammation in patients with APE when compared to patients with normal gingival anatomy.

METHODS

A localized experimental gingivitis was induced in 9 patients with APE (test group) and 9 patients without APE (control group) in the maxillary right quadrant. After 21 days, patients were instructed to resume proper home oral hygiene procedures. At baseline (day 0) and at days 7, 14, 21, 28, 35, and 42, plaque index (PlI), gingival index (GI), and gingival crevicular fluid volume (GCF) were evaluated for teeth 6 (canine), 7 (lateral incisor) and 8 (central incisor) of test and control groups.

RESULTS

During the experimental gingivitis phase (days 0 to 21), the rate of change in gingival inflammation (GI) was dramatically different between the APE test group and the control group. On day 21, at the time of maximum plaque accumulation, the GI of the APE test group was a 109% greater than the GI of the test group (P ≤ 0.001) despite similar plaque levels (P = 0.436). During the resolution of inflammation phase (days 22 to 42), the APE test group continued to exhibit statistically higher GI scores than the control group (P = 0.029).

CONCLUSION

In the presence of similar amounts of plaque deposits and plaque accumulation rates, APE patients exhibited differences in the development and resolution of plaque-induced gingival inflammation when compared to controls.

Digital smile design for gummy smile correction

Some tools can be used as an aid to the surgical planning for gummy smile correction, such as digital smile design (DSD), which allows to determine patterns of harmony and eventual asymmetries between teeth and gums. This work aims to report a gummy smile correction using DSD as reverse planning. The clinical examination revealed the presence of gummy smile and extensive bone exostosis in the premolar region. DSD was performed in the upper arch, determining the amount of gingiva to be removed, thus providing more safety and precision to the procedure. The surgery was performed by performing using an internal bevel incisions, detachment of a full thickness flap, and osteotomy and osteoplasty. After 6 months of preservation, there was an increase in the clinical crown of the teeth, with smile harmony, less exposure of the gingiva in the smile and a high level of patient aesthetic satisfaction.

Spontaneous Eruption of a Deeply Impacted Premolar After Conservative Treatment of an Associated Dentigerous Cyst: A Case Report

Dentigerous cysts are benign odontogenic cysts that develop around the crowns of permanent teeth and are considered rare in children. This article reports a case of a 10-year-old girl with an inflammatory dentigerous cyst associated with the right mandibular premolar and deeply displacing it to the lower border of the mandible. To preserve the developing mandibular premolar and the mental nerve, marsupialization of the lesion under local anesthesia was performed. During the first month postoperatively, the impacted premolar naturally started to correct its position towards the normal path of eruption. After 13 months of follow-up, full spontaneous eruption of the impacted premolar with complete resolution of the cystic lesion, new bone formation, and closure of the root apex were observed. The use of marsupialization as a first-line approach is encouraged to treat dentigerous cysts in children, as it has been reported effective in terms of conservative management.

A three-dimensional analysis of primary failure of eruption in humans and mice

OBJECTIVES

Primary failure of eruption (PFE) is a genetic disorder exhibiting the cessation of tooth eruption. Loss-of-function mutations in parathyroid hormone (PTH)/parathyroid hormone-related peptide (PTHrP) receptor (PTH/PTHrP receptor, PPR) were reported as the underlying cause of this disorder in humans. We showed in a PFE mouse model that PTHrP-PPR signaling is responsible for normal dental follicle cell differentiation and tooth eruption. However, the mechanism underlying the eruption defect in PFE remains undefined. In this descriptive study, we aim to chronologically observe tooth eruption and root formation of mouse PFE molars through 3D microCT analyses.

SETTING AND SAMPLE POPULATION

Two individuals with PFE were recruited at Showa University. A mouse PFE model was generated by deleting PPR specifically in PTHrP-expressing dental follicle and divided into three groups, PPR^fl/fl ;R26R^tdTomato/+ (Control), PTHrP-creER;PPR^fl/+ ;R26R^tdTomato/+ (cHet), and PTHrP-creER;PRR^fl/fl ;R26R^tdTomato/+ (cKO).

MATERIALS AND METHODS

Images from human PFE subjects were acquired by CBCT. All groups of mouse samples were studied at postnatal days 14, 25, 91, and 182 after a tamoxifen pulse at P3, and superimposition of 3D microCT images among three groups was rendered.

RESULTS

Mouse and human PFE molars exhibited a similar presentation in the 3D CT analyses. The quantitative analysis in mice demonstrated a statistically significant decrease in the eruption height of cKO first and second molars compared to other groups after postnatal day 25. Additionally, cKO molars demonstrated significantly shortened roots with dilacerations associated with the reduced interradicular bone height.

CONCLUSIONS

Mouse PFE molars erupt at a much slower rate compared to normal molars, associated with shortened and dilacerated roots and defective interradicular bones.