Natural and hybrid immunity after SARS-CoV-2 infection in children and adolescents.

PURPOSE: In contrast to adults, immune protection against SARS-CoV-2 in children and adolescents with natural or hybrid immunity is still poorly understood. The aim of this study was to analyze different immune compartments in different age groups and whether humoral immune reactions correlate with a cellular immune response. METHODS: 72 children and adolescents with a preceding SARS-CoV-2 infection were recruited. 37 were vaccinated with an RNA vaccine (BNT162b2). Humoral immunity was analyzed 3-26 months (median 10 months) after infection by measuring Spike protein (S), nucleocapsid (NCP), and neutralizing antibodies (nAB). Cellular immunity was analyzed using a SARS-CoV-2-specific interferon-γ release assay (IGRA). RESULTS: All children and adolescents had S antibodies; titers were higher in those with hybrid immunity (14,900 BAU/ml vs. 2118 BAU/ml). NCP antibodies were detectable in > 90%. Neutralizing antibodies (nAB) were more frequently detected (90%) with higher titers (1914 RLU) in adolescents with hybrid immunity than in children with natural immunity (62.5%, 476 RLU). Children with natural immunity were less likely to have reactive IGRAs (43.8%) than adolescents with hybrid immunity (85%). The amount of interferon-γ released by T cells was comparable in natural and hybrid immunity. CONCLUSION: Spike antibodies are the most reliable markers to monitor an immune reaction against SARS-CoV-2. High antibody titers of spike antibodies and nAB correlated with cellular immunity, a phenomenon found only in adolescents with hybrid immunity. Hybrid immunity is associated with markedly higher antibody titers and a higher probability of a cellular immune response than a natural immunity.

Nutritional Management in Children and Adolescents with Severe Neurological Impairment-Who Cares? A Web-Based Survey Among Pediatric Specialists in Germany.

BACKGROUND: Nutritional management of children and adolescents with severe neurological impairment (SNI) is challenging. A web-based survey was distributed to identify the present situation and the knowledge of the involved medical professionals in Germany. METHODS: The survey was created with LimeSurvey, and access data were distributed by several medical societies. Eighty-three questions covered four topics: "general information," "gastro- and jejunostomy procedure," "handling of gastrostomies and feeding tubes," and "nutritional management and follow-up of children and adolescents with SNI." A descriptive analysis was performed with Microsoft Excel. RESULTS: A total of 156 participated (65 completed and 91 partially), 27% being pediatric gastroenterologists, 23% pediatric neurologists, and 10% pediatric surgeons. The most common indications for gastrostomy and tube feeding were oropharyngeal dysfunction and failure to thrive. Many patients were still underweight after some months of enteral feeding. The procedure of gastrostomy and handling recommendations varied broadly. Frequently, standard operating procedures (SOPs) and written local guidelines did not exist, and there was a considerable request for training. Only 53% of participants were aware of the European Society for Paediatric Gastroenterology, Hepatology and Nutrition position paper published in 2017, even fewer (38%) followed the guidelines. The recommended measures to assess a nutritional status were often not respected. CONCLUSION: Nutritional management of children and adolescents with SNI in Germany is still strongly deficient. Despite the international guideline of 2017, few colleagues are aware of and adhere to the recommendations. This could be improved by interdisciplinary teaching and evaluation of the reasons for noncompliance. The procedure of gastrostomy and the patients' follow-up vary widely. Therefore, modified SOPs should be developed.

[The challenges of managing thoracic pain in cystic fibrosis (CF)]. / Herausforderungen der Therapie thorakaler Schmerzen bei zystischer Fibrose (CF).

BACKGROUND: Cystic fibrosis (CF) is a rare genetic multisystemic disorder with progressive abdominal and pulmonary involvement. Pain is still an underestimated symptom in CF patients. METHODS: A comprehensive review of guidelines and scientific literature on the topic was performed and combined with findings from pain management in a young CF patient with progressive thoracic pain. RESULTS: German CF guidelines do not cover diagnosis and management of pain in these patients. Studies from Europe and the United States report interactions between intensity of pain and mortality in CF, but do not include data on the efficacy of pain management. These data and clinical observations of a CF patient with episodes of intense thoracic pain are used to illustrate the specific challenges in pain relief. CONCLUSION: Pain management in CF requires meticulous monitoring as well as an interdisciplinary approach and should be implemented in the German CF guidelines. The authors also want to suggest recommendations for the treatment of thoracic pain in CF. The range and severity of organ involvement complicates the use both of opioids and non-opioids. Especially opioid treatment carries the risk of hypoxia and opioid-induced constipation (OIC) and needs close medical supervision.

The impact of COPD on polyneuropathy: results from the German COPD cohort COSYCONET.

BACKGROUND: Peripheral neuropathy is a common comorbidity in COPD. We aimed to investigate associations between alterations commonly found in COPD and peripheral neuropathy, with particular emphasize on the distinction between direct and indirect effects. METHODS: We used visit 4 data of the COPD cohort COSYCONET, which included indicators of polyneuropathy (repeated tuning fork and monofilament testing), excluding patients with diabetes a/o increased HbA1c. These indicators were analysed for the association with COPD characteristics, including lung function, blood gases, 6-min walk distance (6-MWD), timed-up-and-go-test (TUG), exacerbation risk according to GOLD, C-reactive protein (CRP), and ankle-brachial index (ABI). Based on the results of conventional regression analyses adjusted for age, BMI, packyears and gender, we utilized structural equation modelling (SEM) to quantify the network of direct and indirect relationships between parameters. RESULTS: 606 patients were eligible for analysis. The indices of polyneuropathy were highly correlated with each other and related to base excess (BE), ABI and TUG. ABI was linked to neuropathy and 6-MWD, exacerbations depended on FEV1, 6-MWD and CRP. The associations could be summarized into a SEM comprising polyneuropathy as a latent variable (PNP) with three measured indicator variables. Importantly, PNP was directly dependent on ABI and particularly on BE. When also including patients with diabetes and/or elevated values of HbA1c (n = 742) the SEM remained virtually the same. CONCLUSION: We identified BE and ABI as major determinants of peripheral neuropathy in patients with COPD. All other associations, particularly those with lung function and physical capacity, were indirect. These findings underline the importance of alterations of the micromilieu in COPD, in particular the degree of metabolic compensation and vascular status.

[Current Practice of Pre- and Postnatal Screening and Future Developments for Evidence Based Guidelines]. / Aktueller Stand und zukünftige Entwicklung der prä- und postnatalen Vorsorge- bzw. Screeninguntersuchungen ­ Evidenz tut Not.

Objectives: In this selective review we provide an overview of the current pre- and postnatal screenings up to 18 years established in Germany to inform physicians of different medical fields (gynecologists, pediatricians, general practitioners, other medical specialists who treat children, adolescents or pregnant females). Current State: Research on screening for different types of cancer has frequently failed to show any benefit. Thus, there is a need to broaden the evidence basis related to medical screenings especially for children and adolescents. Outlook: Potential future developments of pre- and postnatal screenings are illustrated including their social impact. The lack of an early detection of mental health problems is pointed out. An interdisciplinary collaboration and research is required to accumulate evidence with regard to medical screenings and to consider health economic and ethical aspects.

[Cognitive Development in Children with Benign Rolandic Epilepsy of Childhood with Centrotemporal Spikes - Results of a Current Systematic Database Search]. / Kognitive Entwicklung von Kindern mit benigner Epilepsie des Kindesalters mit zentrotemporalen Spitzen (Rolando-Epilepsie) ­ Ergebnisse einer aktuellen systematischen Literaturrecherche.

Benign Rolandic Epilepsy (BRE) is one of the most common epilepsy syndromes in childhood. Although global intellectual performance is typically normal in BRE-patients, problems were found in specific cognitive domains. To summarize recent empirical findings concerning cognitive development in children with BRE a systematic literature search of clinical studies published between 2009 and 2015 was performed. 19 studies of relevance were found.In most recent studies children with BRE consistently showed general intellectual performance within the normal range. However, in two of the studies patients showed a significantly poorer (but still normal) performance in comparison to controls. The studies provide clear indications for a high prevalence of impairments in language (10 out of 12 studies) and academic performance (6 out of 8 studies) in children with BRE. Regarding deficits in other cognitive domains (attention, memory, visual/auditory perception, executive functions) current findings are inconsistent. In addition, no clear results are found in studies examining cognitive development after remission of BRE. Studies on the relationship between selected clinical/electroencephalographic characteristics (e. g. EEG-patterns, focus lateralization) and cognitive performance and studies on potential benefits of anti-epileptic therapy for cognitive functions also have not yielded consistent results. Studies using fMRI and evoked potentials provide evidence for functional reorganization of neural networks in BRE.Due to the developmental risks in children with BRE early cognitive assessment, early treatment and follow-up assessments are important.

Preliminary investigation into the pollution reduction performance of swales used in a stormwater treatment train.

Permeable pavements have been shown to be effective stormwater treatment devices that can greatly reduce surface runoff and significantly improve the quality of stormwater runoff in urban areas. However, the potential problems with sediment clogging and consequent maintenance requirements have been identified as the main barriers to more widespread adoption of permeable pavements in urban developments. This Australian study investigates the effectiveness of using grass swales as pre-treatment devices for permeable pavements in order to reduce clogging and extend the life span of these systems. The results of simulated runoff experiments demonstrated that between 50 and 75% of the total suspended sediment (TSS) was removed within the first 10 m of the swale length. This suggests swales of this length could potentially increase the effective life of permeable pavement systems by reducing clogging, and therefore maintenance. Nutrient removal was also tested in the study and the results indicated the tested swales were of limited effectiveness in the removal of these pollutants. However, in real runoff situations, reduction of TSS will have a direct influence on removing nutrients because a significant proportion of nutrients (and other pollutants) are attached to the sediments.

Molecular characterization of folate receptor 1 mutations delineates cerebral folate transport deficiency.

Cerebral folate transport deficiency is an inherited brain-specific folate transport defect that is caused by mutations in the folate receptor 1 gene coding for folate receptor alpha (FRα). This genetic defect gives rise to a progressive neurological disorder with late infantile onset. We screened 72 children with low 5-methyltetrahydrofolate concentrations in the cerebrospinal fluid and neurological symptoms that developed after infancy. We identified nucleotide alterations in the folate receptor 1 gene in 10 individuals who shared developmental regression, ataxia, profound cerebral hypomyelination and cerebellar atrophy. We found four novel pathogenic alleles, one splice mutation and three missense mutations. Heterologous expression of the missense mutations, including previously described mutants, revealed minor decrease in protein expression but loss of cell surface localization, mistargeting to intracellular compartments and thus absence of cellular binding of folic acid. These results explain the functional loss of folate receptor alpha for all detected folate receptor 1 mutations. Three individuals presenting a milder clinical phenotype revealed very similar biochemical and brain imaging data but partially shared pathogenic alleles with more severely affected patients. Thus, our studies suggest that different clinical severities do not necessarily correlate with residual function of folate receptor alpha mutants and indicate that additional factors contribute to the clinical phenotype in cerebral folate transport deficiency.

Characteristic retinal atrophy pattern allows differentiation between pediatric MOGAD and MS after a single optic neuritis episode.

BACKGROUND: Optic neuritis (ON) is the most prevalent manifestation of pediatric multiple sclerosis (MSped) and myelin-oligodendrocyte glycoprotein antibody-associated disease (MOGADped) in children > 6 years. In this study, we investigated retinal atrophy patterns and diagnostic accuracy of optical coherence tomography (OCT) in differentiating between both diseases after the first ON episode. METHODS: Patients were retrospectively identified in eight tertial referral centers. OCT, VEP and high/low-contrast visual acuity (HCVA/LCVA) have been investigated > 6 months after the first ON. Prevalence of pathological OCT findings was identified based on data of 144 age-matched healthy controls. RESULTS: Thirteen MOGADped (10.7 ± 4.2 years, F:M 8:5, 21 ON eyes) and 21 MSped (14.3 ± 2.4 years, F:M 19:2, 24 ON eyes) patients were recruited. We observed a significantly more profound atrophy of both peripapillary and macular retinal nerve fiber layer in MOGADped compared to MSped (pRNFL global: 68.2 ± 16.9 vs. 89.4 ± 12.3 µm, p < 0.001; mRNFL: 0.12 ± 0.01 vs. 0.14 ± 0.01 mm3, p < 0.001). Neither other macular layers nor P100 latency differed. MOGADped developed global atrophy affecting all peripapillary segments, while MSped displayed predominantly temporal thinning. Nasal pRNFL allowed differentiation between both diseases with the highest diagnostic accuracy (AUC = 0.902, cutoff < 62.5 µm, 90.5% sensitivity and 70.8% specificity for MOGADped). OCT was also substantially more sensitive compared to VEP in identification of ON eyes in MOGAD (pathological findings in 90% vs. 14%, p = 0.016). CONCLUSION: First MOGAD-ON results in a more severe global peripapillary atrophy compared to predominantly temporal thinning in MS-ON. Nasal pRNFL allows differentiation between both diseases with the highest accuracy, supporting the additional diagnostic value of OCT in children with ON.

Current application of National Institute for Health and Clinical Excellence (NICE) guidance in the management of patients with severe psoriasis: a clinical audit against NICE guidance in seven National Health Service specialist dermatology units in England.

BACKGROUND: Psoriasis affects 1-2% of the U.K. population, with 20-30% of those affected having severe psoriasis managed with systemic therapies. Biological agents are a useful option when other systemic therapies have failed. The National Institute for Health and Clinical Excellence (NICE) in the U.K. has published three sets of guidance relating to the use of biological agents. AIM: To establish whether biological agents were being used in line with NICE guidance. METHODS: The study was conducted in seven specialist dermatology units, and involved the retrospective collection of data from patients treated with biological agents since the introduction of the NICE guidance. RESULTS: In total, 176 patients with 212 episodes of treatment were included in the study. Biologics were started for appropriately severe disease in 85% of cases (n = 180) and only after failure, intolerance or contraindication to standard systemic therapies in 97% of cases (n = 206). Etanercept was discontinued appropriately in responders before week 24 in only 12% (five of 60 responders). Across all agents, 40% (72 of 178 with continuity status) were continued on treatment despite not achieving an adequate response according to NICE criteria. CONCLUSIONS: In the seven sites audited, compliance with national guidance was entirely appropriate in terms of therapy initiation; however, the requirement to discontinue etanercept in responders was rarely followed. Similarly, discontinuation of biologicals in nonresponders was not routine practice. This may indicate a reluctance of both patients and clinicians to withdraw an at least partly effective therapy from these refractory patients.

Recurrent upper motor neuron facial weakness of possible epileptic etiology: a case report.

We report on an otherwise healthy infant who presented with clusters of alternating central facial nerve paresis. At 11 months of age, the patient showed intermittent facial asymmetry compatible with right-sided upper motor neuron facial paresis and accompanying incomplete upper motor neuron hypoglossal paresis. Laboratory work-up and imaging studies did not reveal signs of infection, infarction or structural lesions, and after one week, symptoms spontaneously resolved. Similar episodes affecting alternate sides were noted at ages of 17, 27 and 49 months lasting for 4-14 days. At 49 months, EEG showed right temporo-occipital benign sharp waves with activation during drowsiness and sleep. A diagnosis of benign focal epilepsy with negative motor phenomena was made. She is now 60 months old and no further episodes have occurred without antiepileptic treatment. Ictal orofacial phenomena are the clinical hallmark of benign focal epilepsy with centro-temporal sharp waves (BECTS). As in our patient, negative epileptic motor phenomena frequently lead to a broad diagnostic work-up. In infants presenting with episodic central facial nerve paresis, the possibility of negative epileptic motor phenomena should be considered.

Safety of glucose-containing solutions during accidental hyperinfusion in piglets.

BACKGROUND: Errors in fluid management can lead to significant morbidity in children. We conducted an experimental animal study to determine the margin of safety in accidental hyperinfusion of different glucose and electrolyte containing solutions. METHODS: Fifteen piglets [bodyweight 12.1 (sd 2.0) kg] were randomly assigned to receive either 100 ml kg⁻¹ of balanced electrolyte solution with glucose 1% (BS-G1), hypotonic electrolyte solution with glucose 5% (HE-G5), or glucose 40% solution (G40) over 1 h. Blood electrolytes, glucose, and osmolality and intracranial pressure (ICP) were measured before, during, and after fluid administration. RESULTS: Hyperinfusion of BS-G1 led to moderate hyperglycaemia [baseline 3.4 (sd 1.3) mmol litre⁻¹, study end 12.6 (1.8) mmol litre⁻¹], but no other relevant pathophysiological alterations. Hyperinfusion of HE-G5 produced marked hyperglycaemia [baseline 3.9 (1.2) mmol litre⁻¹, study end 48.6 (4.3) mmol litre⁻¹, P < 0.05] and hyponatraemia [baseline 136.4 (1.3) mmol litre(-1), study end 119.6 (2.1) mmol litre⁻¹, P < 0.05], whereas osmolality remained stable during the course of the study. Hyperinfusion of G40 induced acute hyperglycaemic/hyperosmolar decompensation with an extreme decrease in serum electrolytes [e.g. sodium baseline 138 (1.1) mmol litre⁻¹, 30 min 87.8 (6.4) mmol litre⁻¹, P < 0.01], leading to cardiac arrest after infusion of 50-75 ml kg⁻¹. ICP remained within a physiological range in all groups. CONCLUSIONS: In an animal model of accidental hyperinfusion, BS-G1 showed the widest margin of safety and can therefore be expected to enhance patient safety in perioperative fluid management in children; HE-G5 proved significantly less safe; and G40 was found to be outright hazardous.

Schimke immuno-osseous dysplasia: SMARCAL1 loss-of-function and phenotypic correlation.

BACKGROUND: Schimke immuno-osseous dysplasia (SIOD) is an autosomal recessive pleiotropic disorder caused by mutations in SMARCAL1. SMARCAL1 encodes an enzyme with homology to the SNF2 chromatin remodelling proteins. METHODS: To assess the affect of SMARCAL1 mutations associated with SIOD on SMARCAL1 expression and function, we characterised the effects of various mutations on mRNA and protein expression in patient tissues and cell lines, and the ATPase activity, subcellular localisation, and chromatin binding of SMARCAL1 missense mutants. RESULTS: The SIOD associated SMARCAL1 mutations affected SMARCAL1 protein expression, stability, subcellular localisation, chromatin binding, and enzymatic activity. Further, expressing SMARCAL1 missense mutants in Drosophila melanogaster showed that disease severity was inversely proportionate to overall SMARCAL1 activity. CONCLUSION: Our results show for the first time that SMARCAL1 binds chromatin in vivo and that SIOD arises from impairment of diverse SMARCAL1 functions.

Developmental changes of oxalate excretion in enterally fed preterm infants.

To further substantiate gestational age-related changes in oxalate excretion, we studied urinary oxalate excretion in 66 preterm infants born at 23.4-34.7 weeks of gestation. Spot urine of 66 preterm infants was analysed by ion chromatography as soon as they were completely orally fed with enriched breast milk and/or special preterm milk formula (days 7 to 57 of postnatal life). Infants with evidence of renal, gastrointestinal, muscular or metabolic disease were not included. Newborns on parenteral nutrition were excluded. Oxalate/creatinine ratios (Ox/Cr) decreased with gestational age (three age groups: group 1, 23 0/7-28 0/7; group 2, 28 1/7-32 0/7; and group 3, 32 1/7-35 0/7 weeks of gestation). The mean Ox/Cr was highest in group 1 (398.2 mmol/mol +/- 116.8; n = 21). Differences between groups 1 + 3 were statistically significant; p = 0.001; those between groups 1 + 2 and between groups 2 + 3 were not. Ox/Cr correlated inversely with gestational and maturational age (r = -0.41, p = 0.001; r = -0.33, p = 0.007) and positively with postnatal age (r = 0.32, p = 0.008). It correlated inversely with birth weight as well as actual weight at sample collection (r = -0.46 and -0.44, p < 0.001). Ox/Cr was significantly linked to energy and carbohydrate intake (r = 0.3 and 0.4, p = 0.03 and 0.001). These results were independent of sex. In the present study we show that urinary oxalate excretion in preterm infants depends on gestational age.

Scheie syndrome: enzyme replacement therapy does not prevent progression of cervical myelopathy due to spinal cord compression.

Hurler-Scheie syndrome is caused by alpha-l-iduronidase deficiency. Enzyme replacement therapy (ERT) can improve physical capacity and reduces organomegaly. However, the effect on bradytrophic connective tissue is limited. As intravenously administered enzyme cannot cross the blood-brain barrier, the therapy of choice for the more severe Hurler syndrome is haematopoietic stem cell transplantation (HCT). In the more attenuated Scheie syndrome, neurological impairment is less severe; therefore, ERT may be appropriate to treat these patients. Information on long-term outcome in Scheie patients undergoing ERT is scarce. We report a 38-year-old female Scheie patient who has been on ERT for 8 years. While non-neurological symptoms improved, she developed paresthesias in her hands and feet and progressive pain in her legs. Somatosensory evoked potentials were abnormal, suggesting dysfunction of the dorsal funiculus and lemniscus medialis. After 6 years of ERT, a spinal MRI showed dural thickening at the upper cervical spine. These soft-tissue deposits are presumably due to the accumulation of mucopolysaccharides. Intramedullary hyperintensities at the level of C1/2 revealed cervical myelopathy. An MRI before the start of ERT had shown milder spinal lesions. Cystic lesions in the white matter of the centrum semiovale due to dilated Virchow-Robin spaces were essentially unchanged compared with the MRI scan before ERT. Decompression of the spinal cord resulted in clinical improvement. In an adult patient with Scheie syndrome, ERT failed to prevent progression of cervical myelopathy. Clinical significance of cerebral changes is unclear. Whether early HCT or intrathecal ERT could have prevented these lesions remains speculative.

['Cases against KiSS': a diagnostic algorithm for children with torticollis]. / 'Cases against KiSS': A Diagnostic Algorithm for Children with Torticollis.

In 1991, Biedermann coined the term "kinetic imbalance due to suboccipital strain" ("KiSS-syndrome"). He assumed a functional abnormality of the suboccipital-high cervical spine, resulting in positional preference of the infant;s head. A broad spectrum of symptoms and complaints have been attributed to "KiSS-Syndrome". Patients are advised to undergo manual therapy, with pressure applied locally in order to readjust the cervical spine. Life threatening side-effects have been published repeatedly. We present two infants with brain tumours who developed torticollis and further neurological findings such as ataxia and reflex differences. In both cases, symptoms caused by the tumour were interpreted as "KiSS-syndrome", and appropriate diagnostics and therapy were delayed for months. There is no scientific evidence for the actual existence of "KiSS-syndrome" as a clinical entity or for the positive effects of manual therapy. Approximately 12% of all infants <12 months show a positional preference of the head, about 8% present with body asymmetry. Whereas most cases are benign, there is a long list of serious differential diagnoses for torticollis in infants. We give an updated review of the literature regarding "KiSS-Syndrome" and discuss the differential diagnostics in infants with torticollis.

An infiltration approach to reducing pavement damage by street trees.

Planting of street trees in cities and other high-density urban environments can provide significant social, economic and environmental benefits. However, street trees in pavements can often lead to shallow root growth resulting in damage to pavements, kerbs, roads and buried services. This study investigated whether pavement damage by tree roots could be reduced by planting trees in a permeable pavement system with an underlying layer of 20 mm diameter gravel to direct tree roots deeper into the pavement structure. A six-year duration field experiment was conducted to compare the growth of trees and their root systems in a conventional impermeable pavement with growth in a series of permeable pavements with different depths of underlying gravel basecourse. The results demonstrated that permeable pavements with underlying gravel layers encouraged tree roots to travel deeper into the underlying subgrade soil, thereby reducing costly pavement damage. This effect was more pronounced with deeper rather than shallower basecourse layers. While permeable pavements affected tree root growth, they had no significant influence on tree height after six years' growth.

Experimental designs of field-based constructed floating wetland studies: A review.

A Constructed Floating Wetland (CFW) is a relatively recent innovation in stormwater treatment and is a hydroponic device that is designed to move up and down with changing water levels as urban runoff enters a stormwater retention pond. This floating capability is designed to improve the pollutant removal efficiency of the CFW. The CFW studies undertaken so far have produced encouraging results under a range of conditions such as system size, inflow pollutant concentrations, climatic conditions, and coverage ratio. However, these results have not yet been drawn together to better understand how the various design features of a CFW influence its performance. This paper reviews the available field investigations with the aim of helping guide and improve the experimental designs and installations of future CFW installations. This in turn will improve the knowledge and acceptance of these recently developed stormwater treatment systems. One of the findings of this review was that using a percentage coverage design approach may not be as effective as improving the design efficiency. Understanding the hydraulics of the entire pond and CFW system is also critical to effective design. The review also found that the performance evaluation of future CFW installations would be improved if consideration is given to including both baseline monitoring and experimental controls.

Smear layer and surface state affect dentin fluoride uptake.

OBJECTIVES: Polishing generates a smear layer (SL) on in vitro dentin samples that may influence fluoride uptake. We tested two hypotheses: SL increases fluoride uptake in superficial dentin (H1) and decreases fluoride uptake in deeper layers (H2) irrespectively of the amount of fluoride administered. METHODS: Polished bovine dentin with SL present and removed by four methods (5% tannic acid, 20s [TA]; 17% EDTA, 120 s; 38% phosphoric acid, 60s [PA]; and 10s air polishing) was fluoridated with 1200 or 12000 ppm F (NaF) solution (pH 4.0). RESULTS: Scanning electron microscopy (SEM) revealed that aggressiveness of SL removal varied by method from leaving SL patches behind (TA) to collagen exposure (PA). SL increased KOH-soluble and structurally bound fluoride uptake into superficial and deeper layers compared to SL free surfaces (except PA) following 1200 ppm, but not 12000 ppm fluoridation. CONCLUSION: Presence of SL and surface conditions influence dentin fluoride uptake depending on fluoride concentration administered.