Jurassic fossil juvenile reveals prolonged life history in early mammals.

Living mammal groups exhibit rapid juvenile growth with a cessation of growth in adulthood1. Understanding the emergence of this pattern in the earliest mammaliaforms (mammals and their closest extinct relatives) is hindered by a paucity of fossils representing juvenile individuals. We report exceptionally complete juvenile and adult specimens of the Middle Jurassic docodontan Krusatodon, providing anatomical data and insights into the life history of early diverging mammaliaforms. We used synchrotron X-ray micro-computed tomography imaging of cementum growth increments in the teeth2-4 to provide evidence of pace of life in a Mesozoic mammaliaform. The adult was about 7 years and the juvenile 7 to 24 months of age at death and in the process of replacing its deciduous dentition with its final, adult generation. When analysed against a dataset of life history parameters for extant mammals5, the relative sequence of adult tooth eruption was already established in Krusatodon and in the range observed in extant mammals but this development was prolonged, taking place during a longer period as part of a significantly longer maximum lifespan than extant mammals of comparable adult body mass (156 g or less). Our findings suggest that early diverging mammaliaforms did not experience the same life histories as extant small-bodied mammals and the fundamental shift to faster growth over a shorter lifespan may not have taken place in mammaliaforms until during or after the Middle Jurassic.

Developmental origin, functional maintenance and genetic rescue of osteoclasts.

Osteoclasts are multinucleated giant cells that resorb bone, ensuring development and continuous remodelling of the skeleton and the bone marrow haematopoietic niche. Defective osteoclast activity leads to osteopetrosis and bone marrow failure1-9, whereas excess activity can contribute to bone loss and osteoporosis10. Osteopetrosis can be partially treated by bone marrow transplantation in humans and mice11-18, consistent with a haematopoietic origin of osteoclasts13,16,19 and studies that suggest that they develop by fusion of monocytic precursors derived from haematopoietic stem cells in the presence of CSF1 and RANK ligand1,20. However, the developmental origin and lifespan of osteoclasts, and the mechanisms that ensure maintenance of osteoclast function throughout life in vivo remain largely unexplored. Here we report that osteoclasts that colonize fetal ossification centres originate from embryonic erythro-myeloid progenitors21,22. These erythro-myeloid progenitor-derived osteoclasts are required for normal bone development and tooth eruption. Yet, timely transfusion of haematopoietic-stem-cell-derived monocytic cells in newborn mice is sufficient to rescue bone development in early-onset autosomal recessive osteopetrosis. We also found that the postnatal maintenance of osteoclasts, bone mass and the bone marrow cavity involve iterative fusion of circulating blood monocytic cells with long-lived osteoclast syncytia. As a consequence, parabiosis or transfusion of monocytic cells results in long-term gene transfer in osteoclasts in the absence of haematopoietic-stem-cell chimerism, and can rescue an adult-onset osteopetrotic phenotype caused by cathepsin K deficiency23,24. In sum, our results identify the developmental origin of osteoclasts and a mechanism that controls their maintenance in bones after birth. These data suggest strategies to rescue osteoclast deficiency in osteopetrosis and to modulate osteoclast activity in vivo.

Etiological Mechanisms and Genetic/Biological Modulation Related to PTH1R in Primary Failure of Tooth Eruption.

Primary failure of eruption (PFE) is a rare disorder that is characterized by the inability of a molar tooth/teeth to erupt to the occlusal plane or to normally react to orthodontic force. This condition is related to hereditary factors and has been extensively researched over many years. However, the etiological mechanisms of pathogenesis are still not fully understood. Evidence from studies on PFE cases has shown that PFE patients may carry parathyroid hormone 1 receptor (PTH1R) gene mutations, and genetic detection can be used to diagnose PFE at an early stage. PTH1R variants can lead to altered protein structure, impaired protein function, and abnormal biological activities of the cells, which may ultimately impact the behavior of teeth, as observed in PFE. Dental follicle cells play a critical role in tooth eruption and root development and are regulated by parathyroid hormone-related peptide (PTHrP)-PTH1R signaling in their differentiation and other activities. PTHrP-PTH1R signaling also regulates the activity of osteoblasts, osteoclasts and odontoclasts during tooth development and eruption. When interference occurs in the PTHrP-PTH1R signaling pathway, the normal function of dental follicles and bone remodeling are impaired. This review provides an overview of PTH1R variants and their correlation with PFE, and highlights that a disruption of PTHrP-PTH1R signaling impairs the normal process of tooth development and eruption, thus providing insight into the underlying mechanisms related to PTH1R and its role in driving PFE.

Studying eruption patterns of mandibular third molars for forensic age assessment: Introducing current reference data from a population of black South Africans.

INTRODUCTION: Evaluation of the eruption of mandibular third molars in orthopantomograms (OPGs) is a method of forensic age assessment. The objective of our study was to provide valid reference data for this trait within a population of black South Africans. The study was guided by the criteria for reference studies in age assessment. MATERIALS AND METHODS: A study population from Pretoria, South Africa comprising 670 OPGs obtained from 338 black females and 332 black males aged between 15.00 and 25.97 years was analysed. All OPGs were performed for medical indication during the period from 2011 to 2022 and were retrospectively evaluated. From the 670 OPGs, a total of 1021 mandibular third molars were evaluated. The assessment of mandibular third molars was conducted using the staging scale presented by Olze et al. in 2012. Two experienced dentists evaluated the OPGs independently of each other. If the two examiners diverged in their assessments, a consensus stage was assigned. RESULTS: As expected, the mean, median and minimal age increased with higher stages for both teeth and both sexes. The minimum age recorded for stage D, indicating complete tooth eruption, was 15.79 years in females and 16.62 years in males. CONCLUSION: As it is the case for previous reference studies in other countries, placing exclusive reliance on the evaluation of mandibular third molar eruption is inadequate for ascertaining the age of majority among Black South Africans. Future studies need to examine if our results are transferable to other countries in Sub-Saharan Africa.

Accuracy of second and third molar maturity indices, Olze, Haavikko, and Demirjian methods for 14- and 16-year-old age thresholds assessment in Croatian children and adolescents.

This study explores the reliability of four established legal age threshold estimation approaches in a Croatian sample. We applied Haavikko stages, Demirjian stages, Olze's third molar eruption stages, and second and third molar maturity indices measurement in 593 orthopantomograms of Croatian children and adolescents aged 11.00-20.99 years old. The left mandibular second and third molar were assessed. Logistic regression analysis was conducted to test the significance of predictive variables. Logistic Receiver operating characteristic (ROC) curves were performed to evaluate the classification ability of variables for estimating 14- and 16-year-old thresholds. The areas under the ROC curve (AUC), accuracy (Acc), sensitivity (Se), specificity (Sp), Positive Likelihood Ratio (LR +), Negative Likelihood Ratio (LR-), and Bayes post-test probability (Bayes PTP) were calculated to evaluate classification performance. Results suggest that the combination of I2M&I3M is the best classifier for the 14-year-old threshold (AUC = 0.879); for males alone, I2M is an even better classifier (AUC = 0.881). The highest Acc 80.1% (95%CI, 75.9%-83.9%), Bayes PTP 86.5% (95%CI, 82.8%-89.7%) and Sp 88.9% (95%CI, 83.0%-93.3%) were by I3M < 0.81 & I2M < 0.03 in total samples; the highest Acc 86.1% (80.6%- 90.6%), Bayes PTP 87.2% (95%CI, 81.7%- 91.4%) and Sp 87.8% (95%CI, 78.2%- 94.3%) were by I2M < 0.01 in males, Acc of Haavikko Ac and Demirjian H stage in second molar is very close with slightly lower Bayes PTP and Sp. I3M is a good classifier for 16-year-old threshold (AUC = 0.889). The cut-off value I3M < 0.34 can be used to classify the 16-year-old threshold with Acc of 80.6% (95%CI, 77.2%-83.7%), Sp of 83.4% (95%CI, 79.0%-87.3%), and 81.7% (95%CI, 78.4%-84.8%) Bayes PTP. In conclusion, to classify the 14-year-old threshold, a pair of cut-off values I3M < 0.81 & I2M < 0.03 can be used in Croatian females; I2M < 0.01, Demirjian H stage, Haavikko Ac stage in second molar, and the pair I3M < 0.81 & I2M < 0.03 can all be used in Croatian males. I3M < 0.34 can classify the 16-year-old threshold in Croatian populations.

Epigenetic markers of tooth eruption - DNA methylation and histone acetylation.

The present study aimed to evaluate whether epigenetic markers are expressed in the dental follicles surrounding ectopically erupting teeth. Twenty-one dental follicles were collected in 20 adolescent children through surgical exposure of ectopic teeth. The epigenetic modifications of DNA methylation and histone acetylation were evaluated by immunohistochemistry. The results showed cells positive for DNA-methyltransferase 1 (DNMT1), DNA methyltransferase 3 beta (DNMT3B), ten-eleven translocation-2 (TET2), acetyl-histone H3 (AcH3), acetyl-histone H4 (AcH4), 5-methylcytosine (5mC), and 5-hydroxymethylcytosine (5hmC) were present in all the samples. The levels of epigenetic markers representing active chromatin (5hmC, AcH3, AcH4, and TET2) were statistically significantly higher than those of markers representing inactive chromatin (5mC, DNMT3B, DNMT1). In conclusion, follicles in ectopic teeth display major epigenetic modifications. In the follicles, epigenetic markers associated with the activation of bone-related genes are more abundant than markers associated with the inactivation of bone-related genes.

Global variations in eruption chronology of permanent teeth: A systematic review and meta-analysis.

OBJECTIVES: Population-based variations have been reported in permanent teeth eruption but only sparse literature exists on the same. A systematic review and meta-analysis were performed to assess the global variations in eruption chronology of permanent teeth in children and adolescents and the role of sexes, jaws and classes of socio-economic status (SES) on timing of eruption was explored. METHODS: The protocol for the systematic review was registered in PROSPERO. An extensive search of PubMed, EMBASE, Google Scholar, EBSCO, Cochrane library, and anthropology databases was carried out until April 2023. Additionally, grey literature search and hand-searching of relevant key journals was done. RESULTS: Overall, 3797 cross-sectional and longitudinal studies were retrieved from multiple databases. A total of 939, 191 participants were included from 80 studies of which, 41 were carried out in Asia, 26 in Europe, 5 in Africa, 4 in North America, and 4 in Oceania. The mandibular first molar eruption was found to be as early as 4.09 years while the maxillary second molar erupted as late as 13.45 years. Using a random effects model, 28 forest plots were generated. Meta-regression interpreted tooth eruption to be earlier in females and in the mandible. CONCLUSIONS: The findings of this study show that the ages of permanent teeth eruption was advanced in the European population followed by Africa and Asia.

Factors Associated With Successful Surgical Exposure of Impacted Maxillary Canines.

PURPOSE: Impacted maxillary canines occur in up to 3% of the population and their eruption is of great importance in establishing, maintaining the shape, aesthetics, and function of the dental arch. Hence, surgical exposure of canines for the purpose of aligning them is a common surgical procedure. This study identifies the frequency and the statistically significant factors associated with successful surgical exposure of impacted maxillary canines and the relative risk factors for repeat surgery. METHODS: This is a retrospective cohort study of 182 patients who underwent surgical exposure of impacted maxillary canines and orthodontic alignment, over a 5-year period between 2014 and 2018. The variables recorded and analyzed included demographics (age and gender), type of surgery (closed or open exposure), grade of surgeon, and radiographic features on orthopantomogram (canine overlap of adjacent tooth root, vertical canine crown height, canine angulation to midline, position of canine root apex). Outcome data recorded were successful surgical exposure and orthodontic alignment and the need for repeat operation or surgical removal due to ankylosis. The data were analyzed to identify the statistically significant correlates of successful surgical exposure and the relative risk factors associated with repeat surgery. RESULTS: A total of 182 patients and 232 bone-impacted maxillary surgical canine exposures were analyzed, as 50 patients had bilateral impaction. Mean age was 15 years (range = 10-38 years), with 122 (67%) female to 60 (33%) male ratio. Total of 222/232 (96%) impacted maxillary canine teeth were successfully surgically exposed and 10/232 (4%) required re-exposure surgery. Correlates of successful surgical exposures were open exposure technique (P < .002) and reduced distance of vertical canine crown height from alveolar bone margin (P < .033). Relative risk factors for repeat surgery were increased age, male, closed surgical exposure, grade of surgeon, central impaction, increased overlap of adjacent root, increased vertical height, increased angulation to midline, canine apex position above second premolar and procedure done under local anesthetics. CONCLUSIONS: This is the largest impacted maxillary canine study to date which has identified the factors that result in successful surgical exposure, hence allow selection of the patients most suitable for this treatment. Secondly, patients with relative risk factors for repeat surgical intervention may be consented appropriately, triaged for a closer orthodontic follow-up and prioritized for surgery to reduce overall treatment time.

Early life stress is associated with earlier emergence of permanent molars.

Exposure to adversity can accelerate biological aging. However, existing biomarkers of early aging are either costly and difficult to collect, like epigenetic signatures, or cannot be detected until late childhood, like pubertal onset. We evaluated the hypothesis that early adversity is associated with earlier molar eruption, an easily assessed measure that has been used to track the length of childhood across primates. In a preregistered analysis (n = 117, ages 4 to 7 y), we demonstrate that lower family income and exposure to adverse childhood experiences (ACEs) are significantly associated with earlier eruption of the first permanent molars, as rated in T2-weighted magnetic resonance images (MRI). We replicate relationships between income and molar eruption in a population-representative dataset (National Health and Nutrition Examination Survey; n = 1,973). These findings suggest that the impact of stress on the pace of biological development is evident in early childhood, and detectable in the timing of molar eruption.

Clinical and radiographic assessment of gummy smile patients with altered passive eruption: a cross-sectional study in a Thai population.

OBJECTIVES: The study aimed to evaluate the clinical crown length (CCL) among patients diagnosed with altered passive eruption (APE), the causes of a gummy smile, the prevalence of APE, and the correlation between parameters. MATERIALS AND METHODS: A total of 86 gummy smile patients (516 teeth) underwent clinical examination and assessment using cone-beam computed tomography (CBCT), photography, and intraoral scanning. RESULTS: Significantly shorter CCL and distance between the cementoenamel junction and bone crest (CEJ-BC) were observed among APE-affected teeth (p < 0.05). Among the patients, 56.1% of patients were diagnosed with APE, and most of them were affected by a combination of APE and hypermobile upper lip (HUL). Based on 183 APE-affected teeth, the prevalence of APE types and subtypes was as follows: APE1A (96; 19.3%), APE1B (78; 15.9%), APE2A (8; 1.6%), and APE2B (1; 0.2%). Positive correlations were found between keratinized gingival width (KGW) and bone thickness (BT), while negative correlations were observed between gingival thickness (GT) and BT. CONCLUSION: Shorter CCL and CEJ-BC were the highlighted features of APE. APE affected approximately half of the gummy smile patients, with most of them presenting with a combination of HUL. Almost teeth affected by APE were classified as Type I, with a nearly equal distribution between subtypes A and B. CLINICAL RELEVANCE: The clinical and radiographic features of APE contribute to a better understanding of this condition and facilitate the management of patients affected by APE. Approximately half of gummy smile patients will require multidisciplinary treatment.

Primary Failure of Dental Eruption Due to Variants Parathyroid Hormone Receptor 1: Retrospective Study and Proposal of Guidelines Treatment.

OBJECTIVE: Primary failure of eruption is characterized by a nonsyndromic defect in tooth eruption in the absence of mechanical obstruction. It is correlated to rare heterozygous variants in the parathyroid hormone receptor 1 gene. The management of primary failure of eruption is complex because many therapies are ineffective. The present study aimed to compare the clinical outcomes of our patients with the findings reported in the literature, and to propose a treatment guideline based on the literature and our experience. METHODS: Retrospective study of patients affected by primary dental eruption failure in the department and analyse of the results and compare with those of the litterature. RESULTS: Twelve patients belonging to 5 families (9 males, 3 females; 13-52 y old) diagnosed and treated in the maxillofacial surgery and stomatology department of the Lille University Hospital were included. All patients showed posterior tooth involvement, and most patients showed bilateral defects. None of the affected teeth had coronal alveolar bone, whereas 6 patients showed root resorption in the affected teeth. Genetic analyses, performed on 11 patients, identified a parathyroid hormone receptor 1 disease-causing variant in 7 of them (63%). Multidisciplinary treatment was required to rehabilitate these patients. Orthodontic interventions, even at an early age, are difficult in affected teeth, which are often blocked or have internal resorption. Moreover, retention of these affected teeth during growth leads to dentoskeletal malocclusions, requiring difficult surgical management in the long term. Therefore, early extraction of these teeth is frequently recommended once the diagnosis has been confirmed. An implant-borne prosthetic rehabilitation can then be achieved at the end of growth after correction of the jaw discrepancy. In case of a late diagnosis, other surgical or noninvasive techniques may be used depending on the clinical situation. Distraction osteogenesis or segmental osteotomy could be discussed for patients with mild phenotypes. CONCLUSIONS: Early diagnosis of primary eruption defects is crucial to offer appropriate management as early as possible, and so to avoid late complicated treatments.

Assessing current clinical eruption stage of mandibular third molars by dental panoramic radiography.

OBJECTIVE: We examined whether dental panoramic radiography (PAN) can be used to identify the clinical stage of eruption of mandibular third molars at the time of radiological examination. MATERIALS AND METHODS: Cross-sectional data included records from clinical oral examination and PANs of university students. In the retrospective analysis of 345 mandibular third molars in 189 participants (20% men, 80% women; mean age 20.7 years; standard deviation [SD] ± 0.6), clinical stages of eruption were compared with their radiographic depth in bone, inclination, and root development. Statistics included χ2, Mann-Whitney U tests, and logistic regression. RESULTS: Significant (p < 0.001) predictor variables for assessing the clinical stage of eruption were radiographic depth in bone and inclination. All teeth radiologically at a depth of the cementoenamel (CE) junction of the neighbouring second molar or deeper were clinically unerupted. Above the CE junction, 80% of vertical and 97% of distoangular teeth were connected to the oral cavity, and 82% of mesioangular and 69% of horizontal teeth were clinically unerupted. CONCLUSION: All teeth below or at the CE junction are clinically unerupted. Above the CE junction, stage of eruption should be assessed together with the inclination, but horizontally inclined teeth are recommended to be verified clinically.

Radiological features and treatment of erupting maxillary canines in relation to the occurrence of dental developmental abnormalities.

OBJECTIVE: This study aimed to investigate the radiological features of the permanent canines and the treatment carried out to ensure their eruption relative to certain features involved in Dental Anomaly Patterns (DAP). MATERIAL AND METHODS: The cross-sectional part of this retrospective register--based study focused on 1,315 dental panoramic tomographs (DPTs) of children aged 8.5-10.5 years, while the longitudinal part involved information on the treatment provided for 1,269 canines after the DPTs and on their eruption into the oral cavity. RESULTS: The canines of the DAP children more often showed evidence of early treatment (p = 0.014), with girls having more frequently interceptive treatment (p = 0.004) and boys early headgear (p = 0.022). Delayed dental age was associated with early treatment (OR 3.29, 95% CI 1.08-9.99). Either no or clear overlapping of a canine with the lateral incisor occurred more often in the DAP children, whereas canine inclination did not differ between the groups. The root development stage of the canine was more often either beginning or well advanced in the DAP children. CONCLUSIONS: The children with dental developmental abnormalities more often showed evidence of early treatment for the canines. Monitoring of the erupting canines after the first mixed stage is important to enable timely early treatment.

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.

Effect of root immaturity and depth of intrusion on spontaneous re-eruption and healing complications: A retrospective analysis.

BACKGROUND/AIMS: Dental trauma resulting in tooth intrusion is a severe injury of permanent dentition, with a prevalence of 0.5%-1.9% among traumatic dental injuries. Currently, treatment guidelines for intruded permanent teeth depend on root development and the degree of intrusion. However, the categorization of tooth maturity as mature or immature simplifies a complex continuum of root development stages. This study aims to investigate the impact of various stages of root development on the success of spontaneous re-eruption (SRE) of intruded teeth. MATERIALS AND METHODS: This retrospective study analysed data from 80 children (125 teeth) aged 6-12 years who experienced dental intrusion between 2018 and 2022. Root maturation was classified based on Cvek's classification, eight were categorized as stage 1, 29 as stage 2, 44 as stage 3, 25 as stage 4, and 19 as stage 5. Intruded teeth with immature roots (Cvek's class 1-4) underwent SRE, while mature teeth (Cvek's class 5) were treated with SRE, orthodontic repositioning, or surgical repositioning based on the degree of intrusion. Primary outcome measures were successful re-eruption and secondary outcomes included observed complications during follow-up. RESULTS: Regression analysis revealed that the patient's age, degree of root maturation, and degree of intrusion significantly affected spontaneous re-eruption (p < .05). SRE was more successful in teeth with Cvek's stages 1 and 2 compared to stages 3 and 4. Complications were associated with the treatment method, degree of root immaturity, and degree of intrusion. CONCLUSION: The study demonstrates that as root maturation progresses, the likelihood of re-eruption decreases, and the risk of pulp necrosis and infection increases. Therefore, teeth in later stages of immaturity (Cvek stage 4) should be repositioned orthodontically or surgically without waiting for spontaneous re-eruption.

Unveiling deception: Characterizing false amber necklace messages on Facebook.

BACKGROUND: Messages promoting the benefits of amber necklaces for children are common on social media, despite their health risks. AIM: This study characterized Facebook posts with false content about the efficacy of amber necklaces in teething. DESIGN: A sample of 500 English-language Facebook posts was analyzed by two investigators to determine the motivations, author's profile, and sentiments of posts. Latent Dirichlet Allocation topic modeling was used to identify salient terms and topics. An intertopic distance map was created to calculate the topic similarity. These data were analyzed using descriptive analysis, the Mann-Whitney U test, Cramer's V test, and multiple logistic regression models, regarding the time since initial posting and interaction metrics. RESULTS: Most posts were made by business profiles and expressed positive sentiments, with social, psychological, and financial motivations. The posts were categorized into the topics "giveaway," "healing features," and "sales." Overperforming scores and total interaction increased with time since the initial posting. Posts with links had higher overperforming scores. CONCLUSION: The findings suggest that Facebook posts about the efficacy of amber necklaces in teething are motivated by financial interests, using psychological and social mechanisms to achieve greater interaction with their target audience.

A retrospective analysis of the patient journey for children with an unerupted maxillary central incisor.

BACKGROUND: Maxillary central incisors (MCI) are the third most impacted teeth. Timely multidisciplinary management is indicated as unerupted incisors can cause functional- and appearance-related distress. AIM: To assess the patient journey for children with unerupted MCI, including referral, clinical assessment, surgical management and follow-up treatment, and highlight areas for improvement, as well as identify factors impacting orthodontic treatment burden (OTB). DESIGN: A retrospective service evaluation of children aged 6-16 years who had surgical management of unerupted MCI under general anaesthetic (GA) between 2018 and 2021. RESULTS: Fifty-two children with 62 unerupted MCI were identified. Mean age at referral was 8.8 years. Most children (82.7%) had supernumerary teeth in the anterior maxilla. Mean time between listing for GA and surgery increased from 4.3 to 15.2 months following the COVID-19 lockdown. Mean age at surgery was 10.4 years. Supernumerary removal and incisor exposure and bond was the most common treatment (56.6%). Most patients required hospital orthodontic treatment post-surgery (65.4%). CONCLUSION: Most children referred were below 9 years (60.1%); these children had reduced OTB compared to those who had been referred at an older age. Stage of root development was also a significant predictor in OTB. An unexpected finding was that conical supernumeraries were found to prevent MCI eruption.

Spontaneous space closure after extraction of permanent first molars in children and adolescents: a systematic review and meta-analysis.

BACKGROUND: Extraction of the permanent first molars is sometimes necessitated in children and adolescents due to deep carious lesions or developmental defects. OBJECTIVE: To estimate the prevalence of spontaneous space closure after extraction of permanent first molars and identify factors associated with it. SEARCH METHODS: Unrestricted searches in five databases for human studies until February 2024. SELECTION CRITERIA: Longitudinal before-and-after (cohort) human studies assessing eruption of the permanent second molars and spontaneous space closure after extraction of the permanent first molar. DATA COLLECTION AND ANALYSIS: Study selection, data extraction, and risk of bias assessment were performed in duplicate. Random-effects meta-analyses of average spontaneous space closure prevalences and odds ratios (OR) with their 95% confidence intervals (CI) were performed, followed by meta-regression/sensitivity/reporting biases' analyses and evaluation of our confidence in effect estimates. RESULTS: Sixteen reports pertaining to 15 studies (1 prospective /14 retrospective) were included covering 1159 patients (ages 5.5-15.0 years [mean 10.0 years]; 45% male on average) and 2310 permanent second molars. The prevalence of spontaneous space closure was higher in the maxilla (nine studies; 85.3%; 95% CI = 73.7%-92.3%) than the mandible (11 studies; 48.1%; 95% CI = 34.5%-62.0%) to a significant extent (nine studies; OR = 7.77; 95% CI = 4.99-12.11; P < 0.001). For both maxillary/mandibular second molars, Demirjian category E was associated with increased space closure odds than earlier/later stages (P < 0.05). Spontaneous space closure in the mandible was seen more often for patients ages 8-10 years (compared with older patients; three studies; OR = 3.32; 95% CI = 1.73-6.36; P < 0.001) and when the mandibular permanent third molar was present (four studies; OR = 2.28; 95% CI = 1.67-3.09; P = 0.003). Additional analyses failed to find any significant modifying factors. LIMITATIONS: The quality of evidence was very low in all instances due to the inclusion of retrospective studies with methodological issues. CONCLUSIONS: Existing evidence indicates that spontaneous space closure in children and adolescents after extraction of the permanent first molar is seen more often in the maxilla than the mandible. Extraction of the permanent first molar at the Demirjian stage E of the second molar and presence of the lower permanent third molar is associated with increased odds of space closure, but uncertainty persists, due to methodological issues of existing studies. REGISTRATION: PROSPERO (CRD42023395371).

Forced eruption in impacted teeth: analysis of failed cases and outcome of re-operation.

BACKGROUND: Forced eruption of an impacted tooth usually requires surgical and orthodontic interventions to successfully bring the tooth into the dental arch. The clinical time required for a forced eruption is difficult to predict before treatment begins and success rates are affected by several factors before and after an eruption. This study was conducted to identify factors that affect the success of forced eruption, the duration of orthodontic treatment of impacted teeth, and the reasons for re-operation and forced eruption failure in a various teeth and cases. METHODS: In this retrospective study, the records regarding the forced eruption of 468 teeth in 371 patients from June 2006 to May 2020 at the Advanced General Dentistry Department of Yonsei University Dental Hospital were initially examined. The records of 214 teeth in 178 patients who completed orthodontic treatment were included in the analysis. Data on patient demographics, tooth characteristics, orthodontic treatment duration, re-operations, and failures were collected from electronic medical records. RESULTS: There was a significant difference in age between the success and failure forced eruption. Factors significantly affecting treatment duration were apex formation, position, rotation, and re-operation. Re-operation had a 96% success rate. The average orthodontic treatment duration was 29.99 ± 16.93 months, but the average orthodontic treatment duration for teeth that undergone re-operation was 20.36 ± 11.05 months, which was approximately 9 months shorter. Additionally, there was an interaction effect between rotation and re-operation on the duration of orthodontic treatment. The causes for failure of forced eruption in 6 cases were ankyloses (3 cases), incomplete alignment with the normal dental arch (2 cases), and a significant deviation in the impacted tooth's location (1 case). CONCLUSIONS: To increase the success rate of forced eruption, age should be considered as a priority, and in order to predict the treatment period, the apex formation status, position in the arch, and rotation should be considered in addition to age. When determining re-operation, considering factors such as ankylosis, root curvature, and apex formation can help in the success of orthodontic treatment.

Comparison of the mandibular retromolar space in adults with different sagittal skeletal types and eruption patterns of the mandibular third-molar: a cone-beam computed tomography study.

BACKGROUND: The mandibular retromolar space (RMS) has not been extensively studied in relation to various sagittal skeletal classes and patterns of third-molar eruption. The objective of this study was to test the null hypothesis that there is no difference in the mandibular RMS among normodivergent subjects with different skeletal classes and patterns of mandibular third-molar eruption, using cone-beam computed tomography (CBCT). METHOD: A total of 105 normodivergent patients (20-40 years) were included in this study. Participants were categorized into Class I, II and III groups based on ANB and further impacted and erupted groups based on the eruption patterns of the mandibular third molars. Measurements of the mandibular RMS were taken at four planes parallel to the occlusal plane, along the cusp line. Comparative analyses were conducted among the three sagittal groups and between the impacted and erupted groups. RESULTS: The Class II group exhibited a statistically smaller RMS (P < 0.05). RMS was found to be larger in third-molar erupted group (P < 0.05). The rates of root contact and third-molar impaction was significantly higher in Class II group. (P < 0.05) CONCLUSIONS: The null hypothesis was rejected. Patients with Skeletal Class II tend to have a smaller mandibular RMS and a higher prevalence of root contact and third-molar impaction. The presence of impacted mandibular third molars was correlated with a shorter RMS. TRIAL REGISTRATION: Retrospectively registered.