Emerging connections between cerebellar development, behaviour and complex brain disorders.

The human cerebellum has a protracted developmental timeline compared with the neocortex, expanding the window of vulnerability to neurological disorders. As the cerebellum is critical for motor behaviour, it is not surprising that most neurodevelopmental disorders share motor deficits as a common sequela. However, evidence gathered since the late 1980s suggests that the cerebellum is involved in motor and non-motor function, including cognition and emotion. More recently, evidence indicates that major neurodevelopmental disorders such as intellectual disability, autism spectrum disorder, attention-deficit hyperactivity disorder and Down syndrome have potential links to abnormal cerebellar development. Out of recent findings from clinical and preclinical studies, the concept of the 'cerebellar connectome' has emerged that can be used as a framework to link the role of cerebellar development to human behaviour, disease states and the design of better therapeutic strategies.

Disruption of neonatal Purkinje cell function underlies injury-related learning deficits.

It is hypothesized that perinatal cerebellar injury leads to long-term functional deficits due to circuit dysmaturation. Using a novel integration of GCaMP6f fiber photometry with automated measurement of cerebellar behavior using the ErasmusLadder, we causally link cerebellar injury to altered Purkinje cell responses during maladaptive behavior. Chemogenetic inhibition of neonatal Purkinje cells is sufficient to phenocopy the effects of perinatal cerebellar injury. Our results uncover a direct link between perinatal cerebellar injury and activity-dependent maturation of cerebellar cortex.

Efficacy of clear aligners vs rapid palatal expanders on palatal volume and surface area in mixed dentition patients: A randomized controlled trial.

INTRODUCTION: This study aimed to evaluate the efficacy of Invisalign First Phase I treatment compared with tooth-borne rapid maxillary expansion (RME) in mixed dentition patients by examining changes in palatal volume, palatal surface area, and maxillary interdental transverse measurements. METHODS: In this open-label, 2-arm, parallel, randomized controlled trial, patients with a posterior transverse discrepancy ≤6 mm were allocated into the clear aligner therapy (CAT) group (Invisalign First Phase I treatment) and RME group (tooth-borne RME) according to a computer-generated randomization list immediately before the start of treatment. Digital models were obtained before the beginning of the treatment (T0) and at the end of the retention period/treatment (T1) using an intraoral scanner. Palatal volume was measured as the primary outcome, and palatal surface area and intermolar and intercanine transverse widths at the cusps and gingival level were measured as secondary outcomes. Patients and interventionists were not blinded because of the nature of the intervention. RESULTS: Out of 50 patients, 41 (19 males and 22 females; mean age, 8.12 ± 1.53 years) were enrolled and divided into 2 groups: 20 in the CAT group and 21 in the RME group. Two participants did not receive the allocated intervention for different reasons (1 patient discontinued the intervention in the CAT group, and another patient was lost to follow-up in the RME group). Thus, 19 patients (5 males and 14 females; mean age, 8.48 ± 1.42 years) were analyzed from the CAT group, and 20 patients (12 males and 8 females; mean age, 7.83 ± 1.19 years) from the RME group. Regarding intragroup comparisons, all outcome measures significantly increased from T0 to T1 in both groups. In terms of intergroup comparisons, there were no significant differences in the variation (Δ) of outcome measures between the 2 groups from T0 to T1, except for the intermolar width at the gingival level (P <0.005). The change in palatal volume was 532.01 ±540.52 mm³ for the RME group and 243.95 ± 473.24 mm³ for the CAT group (P = 0.310), with a moderate effect size (d = ∼1.136). CONCLUSIONS: RME exhibited superior results compared with the Invisalign First Phase I treatment, considering all the assessed outcome measures. The only parameter that showed statistically significant differences between the 2 groups was variation in intermolar width at the gingival level, suggesting the occurrence of buccal tipping in patients undergoing Invisalign First Phase I treatment. TRIAL REGISTRATION: The trial was registered at ClinicalTrial.gov (no. NCT04760535).

Oxidative Stress-Induced Damage to the Developing Hippocampus Is Mediated by GSK3ß.

Neonatal brain injury renders the developing brain vulnerable to oxidative stress, leading to cognitive deficit. However, oxidative stress-induced damage to hippocampal circuits and the mechanisms underlying long-term changes in memory and learning are poorly understood. We used high oxygen tension or hyperoxia (HO) in neonatal mice of both sexes to investigate the role of oxidative stress in hippocampal damage. Perinatal HO induces reactive oxygen species and cell death, together with reduced interneuron maturation, inhibitory postsynaptic currents, and dentate progenitor proliferation. Postinjury interneuron stimulation surprisingly improved inhibitory activity and memory tasks, indicating reversibility. With decreased hippocampal levels of Wnt signaling components and somatostatin, HO aberrantly activated glycogen synthase kinase 3 ß activity. Pharmacological inhibition or ablation of interneuron glycogen synthase kinase 3 ß during HO challenge restored progenitor cell proliferation, interneuron development, inhibitory/excitatory balance, as well as hippocampal-dependent behavior. Biochemical targeting of interneuron function may benefit learning deficits caused by oxidative damage.SIGNIFICANCE STATEMENT Premature infants are especially vulnerable to oxidative stress, as their antioxidant defenses are underdeveloped. Indeed, high oxygen tension is associated with poor neurologic outcomes. Because of its sustained postnatal development and role in learning and memory, the hippocampus is especially vulnerable to oxidative damage in premature infants. However, the role of oxidative stress in the developing hippocampus has yet to be explored. With ever-rising rates of neonatal brain injury and no universally viable approach to maximize functional recovery, a better understanding of the mechanisms underlying neonatal brain injury is needed. Addressing this need, this study uses perinatal hyperoxia to study cognitive deficits, pathophysiology, and molecular mechanisms of oxidative damage in the developing hippocampus.

Intrinsic and extrinsic regulators of oligodendrocyte progenitor proliferation and differentiation.

Oligodendrocytes are highly specialized glial cells, responsible for producing myelin in the central nervous system (CNS). The multi-stage process of oligodendrocyte development is tightly regulated to ensure proper lineage progression of oligodendrocyte progenitor cells (OPCs) to mature myelin producing oligodendrocytes. This developmental process involves complex interactions between several intrinsic signaling pathways that are modulated by an array of extrinsic factors. Understanding these regulatory processes is of crucial importance, as it may help to identify specific molecular targets both to enhance plasticity in the normal CNS and to promote endogenous recovery following injury or disease. This review describes two major regulators that play important functional roles in distinct phases of oligodendrocyte development: OPC proliferation and differentiation. Specifically, we highlight the roles of the extracellular astrocyte/radial glia-derived protein Endothelin-1 in OPC proliferation and the intracellular Akt/mTOR pathway in OPC differentiation. Lastly, we reflect on how recent advances in neuroscience and scientific technology will enable greater understanding into how intrinsic and extrinsic regulators interact to generate oligodendrocyte diversity.

The cortical NG2-glia response to traumatic brain injury.

Traumatic brain injury (TBI) is a significant worldwide cause of morbidity and mortality. A chronic neurologic disease bearing the moniker of "the silent epidemic," TBI currently has no targeted therapies to ameliorate cellular loss or enhance functional recovery. Compared with those of astrocytes, microglia, and peripheral immune cells, the functions and mechanisms of NG2-glia following TBI are far less understood, despite NG2-glia comprising the largest population of regenerative cells in the mature cortex. Here, we synthesize the results from multiple rodent models of TBI, with a focus on cortical NG2-glia proliferation and lineage potential, and propose future avenues for glia researchers to address this unique cell type in TBI. As the molecular mechanisms that regulate NG2-glia regenerative potential are uncovered, we posit that future therapeutic strategies may exploit cortical NG2-glia to augment local cellular recovery following TBI.

The 50 most-cited articles on clear aligner treatment: A bibliometric and visualized analysis.

INTRODUCTION: Research on clear aligner treatment (CAT) has increased in recent years. In this study, we aimed to perform a bibliometric and visualized analysis to identify and critically assess the 50 most highly cited articles on CAT. METHODS: Web of Science was selected as a data source and consulted until March 2020 to identify all articles potentially relevant to the analysis. All the eligible articles were collected until 50 manuscripts were listed. Article-based parameters, journal-based parameters, and author-based parameters were registered to perform the bibliometric analysis. Keywords were automatically harvested from the selected articles to implement the visualized analysis. RESULTS: The search identified a total of 378 articles; the total number of citations of the selected articles varied from 15 to 112. The average number of citations per year varied from 1.15 to 13.83. The predominant study design was clinical (31.7%). Over the 15 journals in which the most cited articles were published, the American Journal of Orthodontics and Dentofacial Orthopedics published the majority of those included in the list (14) and also received the greatest number of citations (671). A total of 195 authors contributed to the 50 most cited articles; a significant portion of them (26) were unaffiliated with academic institutions. A total of 184 keywords were gathered from the article list. CONCLUSIONS: The number of citations on CAT is expected to grow steadily in parallel with the rising number of research projects. The present work identifies the most influential articles on CAT and their characteristics, placing emphasis on the journals, the authors, and the topics addressed.

Intranasal epidermal growth factor treatment rescues neonatal brain injury.

There are no clinically relevant treatments available that improve function in the growing population of very preterm infants (less than 32 weeks' gestation) with neonatal brain injury. Diffuse white matter injury (DWMI) is a common finding in these children and results in chronic neurodevelopmental impairments. As shown recently, failure in oligodendrocyte progenitor cell maturation contributes to DWMI. We demonstrated previously that the epidermal growth factor receptor (EGFR) has an important role in oligodendrocyte development. Here we examine whether enhanced EGFR signalling stimulates the endogenous response of EGFR-expressing progenitor cells during a critical period after brain injury, and promotes cellular and behavioural recovery in the developing brain. Using an established mouse model of very preterm brain injury, we demonstrate that selective overexpression of human EGFR in oligodendrocyte lineage cells or the administration of intranasal heparin-binding EGF immediately after injury decreases oligodendroglia death, enhances generation of new oligodendrocytes from progenitor cells and promotes functional recovery. Furthermore, these interventions diminish ultrastructural abnormalities and alleviate behavioural deficits on white-matter-specific paradigms. Inhibition of EGFR signalling with a molecularly targeted agent used for cancer therapy demonstrates that EGFR activation is an important contributor to oligodendrocyte regeneration and functional recovery after DWMI. Thus, our study provides direct evidence that targeting EGFR in oligodendrocyte progenitor cells at a specific time after injury is clinically feasible and potentially applicable to the treatment of premature children with white matter injury.

Cerebellar contribution to locomotor behavior: A neurodevelopmental perspective.

The developmental trajectory of the formation of cerebellar circuitry has significant implications for locomotor plasticity and adaptive learning at later stages. While there is a wealth of knowledge on the development of locomotor behavior in human infants, children, and adolescents, pre-clinical animal models have fallen behind on the study of the emergence of behavioral motifs in locomotor function across postnatal development. Since cerebellar development is protracted, it is subject to higher risk of genetic or environmental disruption, potentially leading to abnormal behavioral development. This highlights the need for more sophisticated and specific functional analyses of adaptive cerebellar behavior within the context of whole-body locomotion across the entire span of postnatal development. Here we review evidence on cerebellar contribution to adaptive locomotor behavior, highlighting methodologies employed to quantify and categorize behavior at different developmental stages, with the ultimate goal of following the course of early behavioral alterations in neurodevelopmental disorders. Since experimental paradigms used to study cerebellar behavior are lacking in both specificity and applicability to locomotor contexts, we highlight the use of the Erasmus Ladder - an advanced, computerized, fully automated system to quantify adaptive cerebellar learning in conjunction with locomotor function. Finally, we emphasize the need to develop objective, quantitative, behavioral tasks which can track changes in developmental trajectories rather than endpoint measurement at the adult stage of behavior.

Controversies in preterm brain injury.

In this review, we highlight critical unresolved questions in the etiology and mechanisms causing preterm brain injury. Involvement of neurons, glia, endogenous factors and exogenous exposures is considered. The structural and functional correlates of interrupted development and injury in the premature brain are under active investigation, with the hope that the cellular and molecular mechanisms underlying developmental abnormalities in the human preterm brain can be understood, prevented or repaired.

Notch and EGFR pathway interaction regulates neural stem cell number and self-renewal.

Specialized cellular microenvironments, or 'niches', modulate stem cell properties, including cell number, self-renewal and fate decisions. In the adult brain, niches that maintain a source of neural stem cells (NSCs) and neural progenitor cells (NPCs) are the subventricular zone (SVZ) of the lateral ventricle and the dentate gyrus of the hippocampus. The size of the NSC population of the SVZ at any time is the result of several ongoing processes, including self-renewal, cell differentiation, and cell death. Maintaining the balance between NSCs and NPCs in the SVZ niche is critical to supply the brain with specific neural populations, both under normal conditions or after injury. A fundamental question relevant to both normal development and to cell-based repair strategies in the central nervous system is how the balance of different NSC and NPC populations is maintained in the niche. EGFR (epidermal growth factor receptor) and Notch signalling pathways have fundamental roles during development of multicellular organisms. In Drosophila and in Caenorhabditis elegans these pathways may have either cooperative or antagonistic functions. In the SVZ, Notch regulates NSC identity and self-renewal, whereas EGFR specifically affects NPC proliferation and migration. This suggests that interplay of these two pathways may maintain the balance between NSC and NPC numbers. Here we show that functional cell-cell interaction between NPCs and NSCs through EGFR and Notch signalling has a crucial role in maintaining the balance between these cell populations in the SVZ. Enhanced EGFR signalling in vivo results in the expansion of the NPC pool, and reduces NSC number and self-renewal. This occurs through a non-cell-autonomous mechanism involving EGFR-mediated regulation of Notch signalling. Our findings define a novel interaction between EGFR and Notch pathways in the adult SVZ, and thus provide a mechanism for NSC and NPC pool maintenance.

E2F1 coregulates cell cycle genes and chromatin components during the transition of oligodendrocyte progenitors from proliferation to differentiation.

Cell cycle exit is an obligatory step for the differentiation of oligodendrocyte progenitor cells (OPCs) into myelinating cells. A key regulator of the transition from proliferation to quiescence is the E2F/Rb pathway, whose activity is highly regulated in physiological conditions and deregulated in tumors. In this paper we report a lineage-specific decline of nuclear E2F1 during differentiation of rodent OPC into oligodendrocytes (OLs) in developing white matter tracts and in cultured cells. Using chromatin immunoprecipitation (ChIP) and deep-sequencing in mouse and rat OPCs, we identified cell cycle genes (i.e., Cdc2) and chromatin components (i.e., Hmgn1, Hmgn2), including those modulating DNA methylation (i.e., Uhrf1), as E2F1 targets. Binding of E2F1 to chromatin on the gene targets was validated and their expression assessed in developing white matter tracts and cultured OPCs. Increased expression of E2F1 gene targets was also detected in mouse gliomas (that were induced by retroviral transformation of OPCs) compared with normal brain. Together, these data identify E2F1 as a key transcription factor modulating the expression of chromatin components in OPC during the transition from proliferation to differentiation.

Transgenic overexpression of Sox17 promotes oligodendrocyte development and attenuates demyelination.

We have previously demonstrated that Sox17 regulates cell cycle exit and differentiation in oligodendrocyte progenitor cells. Here we investigated its function in white matter (WM) development and adult injury with a newly generated transgenic mouse overexpressing Sox17 in the oligodendrocyte lineage under the CNPase promoter. Sox17 overexpression in CNP-Sox17 mice sequentially promoted postnatal oligodendrogenesis, increasing NG2 progenitor cells from postnatal day (P) 15, then O4+ and CC1+ cells at P30 and P120, respectively. Total Olig2+ oligodendrocyte lineage cells first decreased between P8 and P22 through Sox17-mediated increase in apoptotic cell death, and thereafter significantly exceeded WT levels from P30 when cell death had ceased. CNP-Sox17 mice showed increased Gli2 protein levels and Gli2+ cells in WM, indicating that Sox17 promotes the generation of oligodendrocyte lineage cells through Hedgehog signaling. Sox17 overexpression prevented cell loss after lysolecithin-induced demyelination by increasing Olig2+ and CC1+ cells in response to injury. Furthermore, Sox17 overexpression abolished the injury-induced increase in TCF7L2/TCF4+ cells, and protected oligodendrocytes from apoptosis by preventing decreases in Gli2 and Bcl-2 expression that were observed in WT lesions. Our study thus reveals a biphasic effect of Sox17 overexpression on cell survival and oligodendrocyte formation in the developing WM, and that its potentiation of oligodendrocyte survival in the adult confers resistance to injury and myelin loss. This study demonstrates that overexpression of this transcription factor might be a viable protective strategy to mitigate the consequences of demyelination in the adult WM.

Neonatal hyperoxia exposure disrupts axon-oligodendrocyte integrity in the subcortical white matter.

The pathological mechanisms underlying neurological deficits observed in individuals born prematurely are not completely understood. A common form of injury in the preterm population is periventricular white matter injury (PWMI), a pathology associated with impaired brain development. To mitigate or eliminate PWMI, there is an urgent need to understand the pathological mechanism(s) involved on a neurobiological, structural, and functional level. Recent clinical data suggest that a percentage of premature infants experience relative hyperoxia. Using a hyperoxic model of premature brain injury, we have previously demonstrated that neonatal hyperoxia exposure in the mouse disrupts development of the white matter (WM) by delaying the maturation of the oligodendroglial lineage. In the present study, we address the question of how hyperoxia-induced alterations in WM development affect overall WM integrity and axonal function. We show that neonatal hyperoxia causes ultrastructural changes, including: myelination abnormalities (i.e., reduced myelin thickness and abnormal extramyelin loops) and axonopathy (i.e., altered neurofilament phosphorylation, paranodal defects, and changes in node of Ranvier number and structure). This disruption of axon-oligodendrocyte integrity results in the lasting impairment of conduction properties in the adult WM. Understanding the pathology of premature PWMI injury will allow for the development of interventional strategies to preserve WM integrity and function.

The translational biology of remyelination: past, present, and future.

Amongst neurological diseases, multiple sclerosis (MS) presents an attractive target for regenerative medicine. This is because the primary pathology, the loss of myelin-forming oligodendrocytes, can be followed by a spontaneous and efficient regenerative process called remyelination. While cell transplantation approaches have been explored as a means of replacing lost oligodendrocytes, more recently therapeutic approaches that target the endogenous regenerative process have been favored. This is in large part due to our increasing understanding of (1) the cell types within the adult brain that are able to generate new oligodendrocytes, (2) the mechanisms and pathways by which this achieved, and (3) an emerging awareness of the reasons why remyelination efficiency eventually fails. Here we review some of these advances and also highlight areas where questions remain to be answered in both the biology and translational potential of this important regenerative process.

Effects of preoperative hypoxia on white matter injury associated with cardiopulmonary bypass in a rodent hypoxic and brain slice model.

BACKGROUND: White matter (WM) injury is common after cardiopulmonary bypass or deep hypothermic circulatory arrest in neonates who have cerebral immaturity secondary to in utero hypoxia. The mechanism remains unknown. We investigated effects of preoperative hypoxia on deep hypothermic circulatory arrest-induced WM injury using a combined experimental paradigm in rodents. METHODS: Mice were exposed to hypoxia (prehypoxia). Oxygen-glucose deprivation was performed under three temperatures to simulate brain conditions of deep hypothermic circulatory arrest including ischemia-reperfusion/reoxygenation under hypothermia. RESULTS: WM injury in prenormoxia was identified after 35 °C-oxygen-glucose deprivation. In prehypoxia, injury was displayed in all groups. Among oligodendrocyte stages, the preoligodendrocyte was the most susceptible, while the oligodendrocyte progenitor was resistant to insult. When effects of prehypoxia were assessed, injury of mature oligodendrocytes and oligodendrocyte progenitors in prehypoxia significantly increased as compared with prenormoxia, indicating that mature oligodendrocytes and progenitors that had developed under hypoxia had greater vulnerability. Conversely, damage of oligodendrocyte progenitors in prehypoxia were not identified after 15 °C-oxygen-glucose deprivation, suggesting that susceptible oligodendrocytes exposed to hypoxia are protected by deep hypothermia. CONCLUSION: Developmental alterations due to hypoxia result in an increased WM susceptibility to injury. Promoting WM regeneration by oligodendrocyte progenitors after earlier surgery using deep hypothermia is the most promising approach for successful WM development in congenital heart disease patients.

Hypercapnia Causes Injury of the Cerebral Cortex and Cognitive Deficits in Newborn Piglets.

In critically ill newborns, exposure to hypercapnia (HC) is common and often accepted in neonatal intensive care units to prevent severe lung injury. However, as a "safe" range of arterial partial pressure of carbon dioxide levels in neonates has not been established, the potential impact of HC on the neurodevelopmental outcomes in these newborns remains a matter of concern. Here, in a newborn Yorkshire piglet model of either sex, we show that acute exposure to HC induced persistent cortical neuronal injury, associated cognitive and learning deficits, and long-term suppression of cortical electroencephalogram frequencies. HC induced a transient energy failure in cortical neurons, a persistent dysregulation of calcium-dependent proapoptotic signaling in the cerebral cortex, and activation of the apoptotic cascade, leading to nuclear deoxyribonucleic acid fragmentation. While neither 1 h of HC nor the rapid normalization of HC was associated with changes in cortical bioenergetics, rapid resuscitation resulted in a delayed onset of synaptosomal membrane lipid peroxidation, suggesting a dissociation between energy failure and the occurrence of synaptosomal lipid peroxidation. Even short durations of HC triggered biochemical responses at the subcellular level of the cortical neurons resulting in altered cortical activity and impaired neurobehavior. The deleterious effects of HC on the developing brain should be carefully considered as crucial elements of clinical decisions in the neonatal intensive care unit.

Oligodendrocyte regeneration after neonatal hypoxia requires FoxO1-mediated p27Kip1 expression.

Diffuse white matter injury (DWMI) caused by hypoxia is associated with permanent neurodevelopmental disabilities in preterm infants. The cellular and molecular mechanisms producing DWMI are poorly defined. Using a mouse model of neonatal hypoxia, we demonstrate a biphasic effect on oligodendrocyte development, resulting in hypomyelination. Oligodendrocyte death and oligodendrocyte progenitor cell (OPC) proliferation during the week after hypoxia were followed by delayed oligodendrocyte differentiation and abnormal myelination, as demonstrated by electron microscopy. Cdk2 activation was essential for the regenerative OPC response after hypoxia and was accompanied by reduced FoxO1-dependent p27(Kip1) expression. p27(Kip1) was also reduced in OPCs in human infant white matter lesions after hypoxia. The negative effects of hypoxia on oligodendrogenesis and myelination were more pronounced in p27(Kip1)-null mice; conversely, overexpression of FoxO1 or p27(Kip1) in OPCs after hypoxia promoted oligodendrogenesis. Our studies demonstrate for the first time that neonatal hypoxia affects the Foxo1/p27(Kip1) pathway during white matter development. We also show that molecular manipulation of this pathway enhances oligodendrocyte regeneration during a critical developmental time window after DWMI. Thus, FoxO1 and p27(Kip1) may serve as promising target molecules for promoting timely oligodendrogenesis in neonatal DWMI.

White matter protection in congenital heart surgery.

BACKGROUND: Neurodevelopmental delays in motor skills and white matter (WM) injury have been documented in congenital heart disease and after pediatric cardiac surgery. The lack of a suitable animal model has hampered our understanding of the cellular mechanisms underlying WM injury in these patients. Our aim is to identify an optimal surgical strategy for WM protection to reduce neurological injury in congenital heart disease patients. METHODS AND RESULTS: We developed a porcine cardiopulmonary bypass model that displays area-dependent WM maturation. In this model, WM injury was identified after cardiopulmonary bypass-induced ischemia-reperfusion injury. The degree of injury was inversely correlated with the maturation stage, which indicates maturation-dependent vulnerability of WM. Within different oligodendrocyte developmental stages, we show selective vulnerability of O4+ preoligodendrocytes, whereas oligodendrocyte progenitor cells were resistant to insults. This indicates that immature WM is vulnerable to cardiopulmonary bypass-induced injury but has an intrinsic potential for recovery mediated by endogenous oligodendrocyte progenitor cells. Oligodendrocyte progenitor cell number decreased with age, which suggests that earlier repair allows successful WM development. Oligodendrocyte progenitor cell proliferation was observed within a few days after cardiopulmonary bypass-induced ischemia-reperfusion injury; however, by 4 weeks, arrested oligodendrocyte maturation and delayed myelination were detected. Logistic model confirmed that maintenance of higher oxygenation and reduction of inflammation were effective in minimizing the risk of injury at immature stages of WM development. CONCLUSIONS: Primary repair in neonates and young infants potentially provides successful WM development in congenital heart disease patients. Cardiac surgery during this susceptible period should avoid ischemia-reperfusion injury and minimize inflammation to prevent long-term WM-related neurological impairment.

Temporary anchorage devices in orthodontics: a bibliometric analysis of the 50 most-cited articles from 2012 to 2022.

OBJECTIVES: To identify and analyze the 50 most cited articles on temporary anchorage devices (TADs) and investigate the achievement and development of scientific research about the topic through a bibliometric analysis. MATERIALS AND METHODS: On August 22, 2022, a computerized database search was performed to detect papers published in the scientific literature about TADs from 2012 to 2022. Metrics data were identified using the Incites Journal Citation Reports (Clarivate Analytics) data set. The Scopus database was used to obtain information on the authors' affiliations, country of origin, and h-index. Key words were automatically harvested from the selected articles to implement the visualized analysis. RESULTS: From a total of 1858 papers screened by searching the database, a list of the top 50 most cited articles was created. The total number of citations collected by the 50 most cited articles in TADs was 2380. Among the 50 most cited articles on TADs, 38 were original research papers (76.0%) and 12 were reviews (24.0%). As shown by the key word-network analysis, Orthodontic anchorage procedure was identified as the larger node. CONCLUSIONS: Findings of this bibliometric study showed an increasing number of citations for papers on TADs, accompanied by a simultaneous rise in scientific interest in this topic in the past decade. The present work identifies the most influential articles, emphasizing the journals, the authors, and the topics addressed.