Immobilization of controlled Pu:Am ratio on actinide-specific affinity monolith support developed in capillary and coupled to inductively coupled plasma mass spectrometry.

The objective of this work was to develop an actinide-specific monolithic support in capillary designed to immobilize precise Pu:Am ratios and its coupling to inductively coupled plasma mass spectrometry (ICP-MS) for immobilized metal affinity chromatography applications. This format offers many advantages, such as reducing the sample amount and waste production, which are of prime importance when dealing with highly active radioelements. Four organic phosphorylated-based monoliths were synthesized in situ through UV photo-polymerization in capillary and characterized. The capillary coupling to ICP-MS was set up in conventional laboratory using Th and Sm as chemical analogues of Pu and Am. A dedicated method was developed to quantify online Th and Sm amounts immobilized on the monolithic capillaries, allowing to select the best monolith candidate poly(BMEP-co-EDMA)adp. By precisely adjusting the elemental composition in the loading solutions and applying the developed quantification method, the controlled immobilization of several Th:Sm molar ratios onto the monolith was successful. Finally, the capillary ICP-MS coupling was transposed in a glove box and by applying the strategy developed to design the monolithic support using Th and Sm, the immobilization of a 10.5 ± 0.2 (RSD = 2.3%, n = 3) Pu:Am molar ratio reflecting Pu ageing over 48 years was achieved in a controlled manner on poly(BMEP-co-EDMA)adp. Hence, the new affinity capillary monolithic support was validated, with only hundred nanograms or less of engaged radioelements and can be further exploited to precisely determine differential interactions of Pu and Am with targeted biomolecules in order to better anticipate the effect of Am on Pu biodistribution.

Analysis of the Effect of Exams on Perceived Stress and Temporomandibular Joint Status in Physiotherapy Students: A Pilot Study.

Background and Objectives: Temporomandibular disorders or dysfunction (TMDs) encompass a range of complex conditions that impact the temporomandibular joint (TMJ), chewing muscles, teeth, and/or their supporting tissues. Stress is one of the most associated factors studied as a TMD predictor. The aim is to figure out the influence of stress on TMJ status and salivary cortisol in university students during and before exams. Materials and Methods: The study was non-experimental, employing a longitudinal, analytical, observational cohort design. The study population consisted of students enrolled in the physiotherapy degree program at the Alfonso X El Sabio University (Madrid, Spain). Data were collected during two distinct academic periods: the first period was characterized by low academic stress and no exams, and the second period coincided with the high academic stress of final course exams. The collected results included sociodemographic data, assessment of TMJ status (Fonseca Index), evaluation of muscle evaluation (masseter, upper trapezius, and sternocleidomastoid) using a MOXY Monitor (muscle oxygenation) and Neurotrac® (surface EMG, sEMG), assessment of perceived stress (PSS-14), and measurement of salivary cortisol (enzyme immunoassay with Elisa). The statistical analysis was conducted with a confidence level of 95% (p ≤ 0.05) and asymptotic or bilateral significance. Results: 70 students were analyzed during two different measurement periods. According to the Fonseca Index, initially, 37.14% of the analyzed students showed mild TMDs, 17.14% moderate TMDs, and 45.72% showed no TMDs. In general terms, stress increased with age and is related to female sex, maximum mouth opening decreased with age, oxygen saturation decreased with age and academic stress, and myoglobin concentration was related to age. Furthermore, muscle contraction decreased during higher academic stress and increased with age. For women, age was a risk factor for suffering from TMDs, and stress worsened the transition from having TMDs to having no TMDs in both sexes. Conclusions: Academic stress influences TMJ status and muscle outcomes such as oxygen saturation, myoglobin concentration, and muscle contraction, although more research is needed.

Determining the selectivity of a tetra-phosphorylated biomimetic peptide towards uranium in the presence of competing cations through the simultaneous coupling of HILIC to ESI-MS and ICP-MS.

A cyclic tetra-phosphorylated biomimetic peptide (pS1368) has been proposed as a promising starting structure to design a decorporating agent of uranyl (UO22+) due to its affinity being similar to that of osteopontin (OPN), a target UO22+ protein in vivo. The determination of this peptide's selectivity towards UO22+ in the presence of competing endogenous elements is also crucial to validate this hypothesis. In this context, the selectivity of pS1368 towards UO22+ in the presence of Ca2+, Cu2+ and Zn2+ was determined by applying the simultaneous coupling of hydrophilic interaction chromatography (HILIC) to electrospray ionization (ESI-MS) and inductively coupled plasma (ICP-MS) mass spectrometry. Sr2+ was used as Ca2+ simulant, providing less challenging ICP-MS measurements. The separation of the complexes by HILIC was first set up. The selectivity of pS1368 towards UO22+ was determined in the presence of Sr2+, by adding several proportions of the latter to UO2(pS1368). UO22+ was not displaced from UO2(pS1368) even in the presence of a ten-fold excess of Sr2+. The same approach has been undertaken to demonstrate the selectivity of pS1368 towards UO22+ in the presence of Cu2+, Zn2+ and Sr2+ as competing endogenous cations. Hence, we showed that pS1368 was selective towards UO22+ in the presence of Sr2+, but also in the presence of Cu2+ and Zn2+. This study highlights the performance of HILIC-ESI-MS/ICP-MS simultaneous coupling to assess the potential of molecules as decorporating agents of UO22+.

Access to early-phase clinical trials for children with relapsed and refractory neuroblastoma: A multicentre international study.

OBJECTIVES: Neuroblastoma is the most common extracranial tumour in children, and prognosis for refractory and relapsed disease is still poor. Early-phase clinical trials play a pivotal role in the development of novel drugs. Ensuring adequate recruitment is crucial. The primary aim was to determine the rate of participation trials for children with refractory/relapsed neuroblastoma in two of the largest drug development European institutions. METHODS: Data from patients diagnosed with refractory/relapsed neuroblastoma between January 2012 and December 2018 at the two institutions were collected and analysed. RESULTS: Overall, 48 patients were included. A total of 31 (65%) refractory/relapsed cases were enrolled in early-phase trials. The main reasons for not participating in clinical trials included not fulfilling eligibility criteria prior to consent (12/17, 70%) and screening failure (2/17, 12%). Median time on trial was 4.3 months (range 0.6-13.4). Most common cause for trial discontinuation was disease progression (67.7%). Median overall survival was longer in refractory (28 months, 95% CI: 20.9-40.2) than in relapsed patients (14 months, 95% CI: 8.1-20.1) (p = .034). CONCLUSIONS: Although two thirds of children with refractory/relapsed neuroblastoma were enrolled in early-phase trials, recruitment rates can still be improved. The main cause for not participating on trials was not fulfilling eligibility criteria prior to consent, mainly due to performance status and short life expectancy. This study highlights the hurdles to access to innovative therapies for children with relapsed/refractory neuroblastomas, and identifies key areas of development to improve recruitment to early-phase trials.

Association between dental agenesis and delay in dental development: a preliminary study in a Spanish paediatric population in relation with Dental Anomaly Pattern (DAP).

BACKGROUND: The association between dental anomalies has been studied, giving rise to the concept of Dental Anomaly Pattern (DAP). Tooth agenesis has been associated with alterations such as molar infracclusion, taurodontism and delayed dental development. The aim of this study was to evaluate the dental development pattern in patients with non-syndromic dental agenesis, in comparison with a control group. METHODS: Dental and chronological age was analysed in a sample size of 204 orthopantomographs divided into a study group (n = 104) and a control group (n = 100) with the Demirjian Method. Intra and intergroup differences in chronological and dental age, and the correlation between them were calculated by statistical analysis with a 95% confidence level (p < 0.05). RESULTS: Dental age exceeded chronological age both in the control group and in the study group. Statistically significant differences (p = 0.004) were found when comparing the difference between chronological and dental age in the study (-0.16 ± 1.12) and control group (-0.58 ± 0.90). Regarding sex and age intergroup differences, the results were only statistically significant in the girls' group (p = 0.017), and the age over 8 years old (p < 0.05). There were no significant differences in tooth development depending on the number of missing teeth or the affected tooth group, but there was a delay in the development of the homologous tooth contralateral to the absent one in 14.9% of patients. CONCLUSIONS: The difference between chronological and dental age in permanent dentition is significantly lower in Spanish children with non-syndromic agenesis compared to a control group, presenting a lower dental age than chronological age than children without non-syndromic agenesis.

How Does Iron Storage Protein Ferritin Interact with Plutonium (and Thorium)?

The impact of the contamination of living organisms by actinide elements has been a constant subject of attention since the 1950s. But to date still little is understood. Ferritin is the major storage and regulation protein of iron in many organisms, it consists of a protein ring and a ferrihydric core at the center. This work sheds light on the interactions of early actinides (Th, Pu) at oxidation state +IV with ferritin and its ability to store those elements at physiological pH compared to Fe. The ferritin-thorium load curve suggests that ThIV saturates the protein (2840 Th atoms per ferritin) in a similar way that Fe does on the protein ring. Complementary spectroscopic techniques (spectrophotometry, infrared spectroscopy, and X-ray absorption spectroscopy) were combined with molecular dynamics to provide a structural model of the interaction of ThIV and PuIV with ferritin. Comparison of spectroscopic data together with MD calculations suggests that ThIV and PuIV are complexed mainly on the protein ring and not on the ferrihydric core. Indeed from XAS data, there is no evidence of Fe neighbors in the Th and Pu environments. On the other hand, carboxylates from amino acids of the protein ring and a possible additional carbonate anion are shaping the cation coordination spheres. This thorough description from a molecular view point of ThIV and PuIV interaction with ferritin, an essential iron storage protein, is a cornerstone in comprehensive nuclear toxicology.

Accuracy assessment of dental age estimation with the Willems, Demirjian and Nolla methods in Spanish children: Comparative cross-sectional study.

BACKGROUND: The objective of this study was to evaluate and compare the validity and accuracy of the Willems, Demirjian and Nolla methods in predicting chronological age in a Spanish ethnicity population. METHODS: A sample of 604 orthopantomographs of Spanish children aged 4 to 13 years was evaluated by two independent evaluators. Descriptive statistics were applied to calculate the chronological age and dental age, presenting the mean and standard deviation. The difference between dental age and chronological age was calculated for each method. A positive result indicated an overestimation and a negative figure indicated an underestimation. The Wilcoxon test for paired data and Spearman's correlation coefficient were applied by age groups and sex to compare the chronological age and dental age of each method (that of Willems, Demirjian and Nolla). Statistical tests were performed at a 95% confidence level. RESULTS: The interexaminer agreement was 0.98 (p = 0.00), and the intraexaminer agreement was 0.99 (p = 0.00). The Willems method significantly overestimated the age of boys (0.35 years (0.93)) and girls (0.17 years (0.88)). The Demirjian method significantly overestimated the age of boys (0.68 years (0.95)) and girls (0.73 years (0.94)). The Nolla method significantly underestimated age in boys (0.44 years (0.93)) and girls (0.82 years (0.98)). CONCLUSIONS: In the Spanish population, the use of the Demirjian method for legal and medical purposes is frequent. This study reveals that the Willems method is more appropriate due to its greater precision in estimating dental age.

Which technique is better to place a manoeuvrable vacuum extractor cup on the flexion point? Vacca vs. Bird technique.

Objectives The purpose of this study is to compare the vacuum extractor cup application technique described by Bird vs. the technique described by Vacca on a simulation model. Methods Six obstetricians participated in the study. Each obstetrician performed eight vacuum assisted deliveries using the Bird technique and eight vacuum assisted deliveries using the Vacca 5-Steps technique. Results A total of 96 vacuum assisted deliveries were performed. The mean distance from the centre of the cup to the flexion point was 1.78±0.96 cm for the Bird technique and 1.05±0.60 cm for the Vacca technique (p<0.001). The lateral distance (over the parietal bone) was 1.16±0.69 cm for the Bird technique and 0.66±0.52 cm for the Vacca technique (p<0.001). The vertical distance (towards the frontal or occipital bone) was 1.12±1.02 cm for the Bird technique and 0.67±0.55 cm for the Vacca technique (p=0.009). In occipito anterior positions, there were no significant differences between both techniques. Conclusions The Vacca technique was better in transverse and posterior positions.

Capping of Mn-Doped ZnS Quantum Dots with DHLA for Their Stabilization in Aqueous Media: Determination of the Nanoparticle Number Concentration and Surface Ligand Density.

Colloidal Mn2+-doped ZnS quantum dots (QDs) were synthesized, surface modified, and thoroughly characterized using a pool of complementary techniques. Cap exchange of the native l-cysteine coating of the QDs with dihydrolipoic acid (DHLA) ligands is proposed as a strategy to produce nanocrystals with a strong phosphorescent-type emission and improved aqueous stability. Moreover, such a stable DHLA coating can facilitate further bioconjugation of these QDs to biomolecules using established reagents such as cross-linker molecules. First, a structural and morphological characterization of the l-cysteine QD core was performed by resorting to complementary techniques, including X-ray powder diffraction (XRD) and microscopy tools. XRD patterns provided information about the local structure of ions within the nanocrystal structure and the number of metal atoms constituting the core of a QD. The judicious combination of the data obtained from these complementary characterization tools with the analysis of the QDs using inductively coupled plasma-mass spectrometry (ICP-MS) allowed us to assess the number concentration of nanoparticles in an aqueous sample, a key parameter when such materials are going to be used in bioanalytical or toxicological studies. Asymmetric flow field-flow fractionation (AF4) coupled online to ICP-MS detection proved to be an invaluable tool to compute the number of DHLA molecules attached to the surface of a single QD, a key feature that is difficult to estimate in nanoparticles and that critically affects the behavior of nanoparticles when entering the biological media (e.g., cellular uptake, biodistribution, or protein corona formation). This hybrid technique also allowed us to demonstrate that the elemental composition of the nanoparticle core remains unaffected after the ligand exchange process. Finally, the photostability and robustness of the DHLA-capped QDs, critical parameters for bioanalytical applications, were assessed by molecular luminescence spectroscopy.

Which type of forceps is better for nonrotational operative births? A simulation study comparing Thierry spatulas and Simpson-Braun and Kielland forceps.

OBJECTIVE: Obstetric forceps play an important role in safe childbirth, yet there is a lack of distinction between various forceps types in clinical practice. This study aimed to evaluate and compare perineal pressure and forces on the baby during nonrotational forceps-assisted births using Simpson-Braun forceps, Kielland forceps, and Thierry spatulas on a simulation model. METHODS: This experimental study involved six obstetricians conducting 108 forceps-assisted births on a simulation model. Instruments were assessed for their impact on perineal pressure, traction force, and operator-assessed difficulty. RESULTS: Thierry's spatulas exerted the lowest force on the baby, while Kielland forceps exhibited the lowest perineal pressure, though not statistically significant. An experienced obstetrician demonstrated less perineal pressure with Simpson forceps. Notably, no significant differences in difficulty were observed between instruments. CONCLUSION: This study highlights distinctions in forceps performance, with Thierry spatulas applying the least force on the fetal head, while an experienced obstetrician fared better with Simpson forceps in terms of perineal pressure. Kielland forceps remain a viable alternative for nonrotational forceps births, showing comparable outcomes.

Comparative Analysis of the Comfort of Children and Adolescents in Digital and Conventional Full-Arch Impression Methods: A Crossover Randomized Trial.

The aim of this study was to evaluate the comfort of children and adolescents with conventional full-arch dental impression methods compared to two intraoral scanners (iTeroTM and PrimescanTM). METHODS: A monocentric, analytical, controlled crossover study was designed to compare conventional impression and digital impression with two intraoral scanners (iTeroTM and PrimescanTM) in children and teenagers. Patient comfort was evaluated using a 100 mm VAS scale adapted to Spanish and for children. A descriptive and analytical statistical method was conducted with a confidence level of 95% (p ≤ 0.05) and asymptotic or bilateral significance. RESULTS: A total of 51 subjects were enrolled in the study (mean age = 12.35 years). Although the group of 10-14-year-olds was the most numerous, gender was equally distributed among the age groups. None of the variables on the VAS scale showed differences between the gender categories (p > 0.05). There were differences (p < 0.05) with respect to the age categories, as the middle adolescent group showed the worst general perception and total comfort during the conventional impression. Statistically significant differences were found between all VAS scale items and the three impression methods (p < 0.05). CONCLUSIONS: The digital impression technique is superior in terms of total comfort to the conventional alginate impression in children and adolescents.

Determination of the affinity of biomimetic peptides for uranium through the simultaneous coupling of HILIC to ESI-MS and ICP-MS.

Several proteins have been identified in the past decades as targets of uranyl (UO22+) in vivo. However, the molecular interactions responsible for this affinity are still poorly known which requires the identification of the UO22+ coordination sites in these proteins. Biomimetic peptides are efficient chemical tools to characterize these sites. In this work, we developed a dedicated analytical method to determine the affinity of biomimetic, synthetic, multi-phosphorylated peptides for UO22+ and evaluate the effect of several structural parameters of these peptides on this affinity at physiological pH. The analytical strategy was based on the implementation of the simultaneous coupling of hydrophilic interaction chromatography (HILIC) with electrospray ionization mass spectrometry (ESI-MS) and inductively coupled plasma mass spectrometry (ICP-MS). An essential step had been devoted to the definition of the best separation conditions of UO22+ complexes formed with di-phosphorylated peptide isomers and also with peptides of different structure and degrees of phosphorylation. We performed the first separations of several sets of UO22+ complexes by HILIC ever reported in the literature. A dedicated method had then been developed for identifying the separated peptide complexes online by ESI-MS and simultaneously quantifying them by ICP-MS, based on uranium quantification using external calibration. Thus, the affinity of the peptides for UO22+ was determined and made it possible to demonstrate that (i) the increasing number of phosphorylated residues (pSer) promotes the affinity of the peptides for UO22+, (ii) the position of the pSer in the peptide backbone has very low impact on this affinity (iii) and finally the cyclic structure of the peptide favors the UO22+ complexation in comparison with the linear structure. These results are in agreement with those previously obtained by spectroscopic techniques, which allowed to validate the method. Through this approach, we obtained essential information to better understand the mechanisms of toxicity of UO22+ at the molecular level and to further develop selective decorporating agents by chelation.

Vacuum-assisted birth in maternal lateral posture versus lithotomy. A simulation study.

OBJECTIVE: Maternal lateral postures provide advantages during childbirth. This study aims to investigate the feasibility of assisting vacuum births in maternal lateral postures in a simulation model. STUDY DESIGN: In a simulation model, four obstetricians and four medical students were randomly allocated to perform vacuum-assisted births first in maternal lateral posture or lithotomy. A modification of Aldo Vacca's 5-step technique was developed to assist vacuum-assisted births in lateral posture. The lateral distance, vertical distance, and distance from the cup center to the flexion point were measured for every placement of the cup. RESULTS AND CONCLUSIONS: A total of 128 vacuum-assisted births were performed. The mean distance to the flexion point was 1.15 ± 0.71 cm for the lithotomy posture and 1.31 ± 0.82 cm for the lateral posture (P = 0.127). There were no statistically significant differences in vacuum extractor cup placement accuracy based on maternal posture. Performing vacuum-assisted births in maternal lateral posture is feasible in a simulation model. The technique is easy to learn, and the differences in cup placement between the lateral and lithotomy postures are small.

Intraoral scanners in children: evaluation of the patient perception, reliability and reproducibility, and chairside time-A systematic review.

Purpose: The aim of this systematic review is to evaluate the perception of the patient, the chairside time, and the reliability and/or reproducibility of intraoral scanners for full arch in pediatric patients. Methods: A data search was performed in four databases (Medline-Pubmed, Scopus, ProQuest and Web of Science) in accordance with the PRISMA 2020 statements. Studies were classified in three categories (patient perception, scanning or impression time and reliability and/or reproducibility). The resources, the data extraction and the quality assessment were carried out independently by two operators. The variables recorded were population characteristics, material and methods aspects and included country, study design and main conclusion. A quality assessment of the selected studies was performed with QUADAS-2 tool, and Kappa-Cohen Index was calculated to analyze examiner agreement. Results: The initial search obtained 681 publications, and finally four studies matching inclusion criteria were selected. The distribution of the studies in the categories was three for the analysis of the patient's perception and scanning or impression time; and two items to assess the reliability and/or reproducibility of intraoral scans. All included studies have a repeated measures-transversal design. The sample size ranged between 26 and 59 children with a mean age. The intraoral scanners evaluated were Lava C.O.S, Cerec Omnicam, TRIOS Classic, TRIOS 3-Cart and TRIOS Ortho. The quality assessment of the studies using QUADAS-2 tool revealed a low risk of bias while evaluating patient perception, but an unclear risk of bias in the analysis of accuracy or chairside time. In relation to the applicability concerns, the patient selection was of high risk of bias. All studies agreed that the patient perception and comfort is better with intraoral scanners in comparison with the conventional method. The accuracy or reliability of the digital procedure is not clear, being clinically acceptable. In relation with the chairside time, it depends on the intraoral scanner, with contradictory data in the different analyzed studies. Conclusion: The use of intraoral scanners in children is a favorable option, finding a significantly higher patient perception and comfort with intraoral scanners compared to the conventional impression method. The evidence for reliability or reproducibility is not strong to date, however, the differences between the intraoral measurements and the digital models would be clinically acceptable.

"Own doctor" presence in a web-based lifestyle intervention for adults with obesity and hypertension: A randomized controlled trial.

Introduction: Online interventions have long been shown to be an effective means to promote a healthy lifestyle, thereby helping to control body weight and blood pressure figures. Likewise, using video modeling is also considered an effective way to guide patients through behavioral interventions. Nonetheless, to the best of our knowledge, this study is the first to analyze how the presence of patients' "own doctor" in the audiovisual content of a web-based lifestyle program ("Living Better") aimed at promoting regular physical exercise and healthy eating behavior, compared with an "unknown doctor," influences the outcomes of adults with obesity and hypertension. Materials and methods: A total of 132 patients were randomly assigned either to the experimental (n = 70) or control (n = 62) group ("own doctor" or "unknown doctor", respectively). The body mass index, systolic and diastolic blood pressure, number of antihypertensive drugs used, physical activity level, and quality of life was assessed and compared at baseline and post-intervention (12 weeks). Results: The intention-to-treat analysis showed intragroup significant improvements in both groups in terms of the body mass index (control group: mean difference -0.3, 95% CI [-0.5, -0.1], p = 0.002; experimental group: -0.4 [-0.6, -0.2], p < 0.001) and systolic blood pressure (control group: -2.3 [-4.4, -0.2], p = 0.029; experimental group: -3.6 [-5.5, -1.6], p< 0.001). In addition, there were also significant improvements in the experimental group for the diastolic blood pressure (-2.5 [-3.7, -1.2], p < 0.001), physical activity (479 [9, 949], p = 0.046), and quality of life (5.2 [2.3, 8.2], p = 0.001). However, when comparing the experimental with the control group, no between-group significant differences were found in these variables. Conclusions: This study suggests that the presence of patients' "own doctor" in the audiovisual content of a web-based intervention, aimed at promoting a healthy lifestyle among adults with obesity and hypertension, do not show significant additional benefits over the efficacy of e-counseling. Trial registration: ClinicalTrials.gov NCT04426877. First Posted: 11/06/2020. https://clinicaltrials.gov/ct2/show/NCT04426877.

How the Presence of a Doctor Known to Patients Impacts a Web-Based Intervention to Promote Physical Activity and Healthy Eating Behaviour in Individuals with an Overweight/Obesity-Hypertension Phenotype: A Randomised Clinical Trial.

(1) Background: The 'Living Better' web-based programme has shown short- and long-term benefits for body composition and psychological variables in obese patients with hypertension by promoting a healthier lifestyle. To further explore the potential of this programme, in this work we aimed to explore the possible effect of the patient's 'own doctor' appearing in the video content of the Living Better intervention. (2) Methods: A total of 132 patients were randomly assigned either to the experimental (EG, n = 70) or control (CG, n = 62) group (with a doctor the patient knew as 'their own' or an 'unknown doctor', respectively). The body mass index (BMI), motivation towards physical activity (PA), PA levels, motivation to change one's eating habits, adherence to the Mediterranean diet, and eating behaviour were all assessed and compared at baseline and post-intervention (12 weeks). (3) Results: The results of this study confirmed the positive effects of the Living Better programme on BMI and external eating style, with significant improvements in these variables in both groups. In addition, in the EG there was higher intrinsic motivation to change eating behaviour (mean difference of 0.9, 95% CI [0.1, 1.6], p = 0.032) and lower amotivation (mean difference of -0.6, 95% CI [-1.2, -0.1], p = 0.027) compared to the CG. (4) Conclusions: This study suggests that the presence of the patients' own doctor in the audiovisual content of the Living Better intervention did not have significant additional benefits in terms of BMI or external eating style. However, their presence did improve intrinsic motivation and amotivation related to eating habits.

In vitro analysis of the influence of the thermocycling and the applied force on orthodontic clear aligners.

The mechanical properties of polyurethane dental aligners have been studied in an oral environment at 37°C and subjected to thermal cycling between 5°C and 55°C for long periods of time at different mechanical stresses. The aim is to determine the efficacy of the orthodontic aligner at different stress levels, the effect of thermal cycling with therapy time on tooth position correction. Sixty aligners with the same design were studied applying tensions of 0, 3 and 30 N and determining the deformation at different times from 1 to 760 h. Half of these aligners were subjected to stresses submerged in artificial saliva at 37°C and the other half were subjected to thermal cycles between 2°C and 55°C in salivary medium. Deformation was determined using a high-resolution stereo magnifier and ImageJ image analysis software. Water adsorption by the polyurethane was determined at the different test times. The results showed that in the unloaded aligners there is no appreciable deformation, but with thermal cycling there is a light shrinkage of the aligner due to the semi-crystallization process (ordering of polymeric chains) of the polyurethane. When applying loads of 3 and 30 N, creep curves with constant deformation transition zones can be seen. The transition zones decrease as the applied mechanical load increases. In addition, the significant effect of thermal cycling on the reduction of the transition zone of the aligners has been demonstrated. The transition zones are optimal for dental correction as constant stresses are exerted for tooth movement. The effect of thermal cycling shortens the constant deformation zone and reduces tooth alignment time. It was observed that the absorption of water in the aligner is constant after 1 h of immersion and does not exceed 0.4% by weight of absorbed water.

Bone Quantification Around Chitosan-Coated Titanium Dental Implants: A Preliminary Study by Micro-CT Analysis in Jaw of a Canine Model.

Surface treatments of Ti in the dental implant industry are performed with the aim of in-creasing its bioactivity and osseointegration capacity. Chitosan (Cht) is a polysaccharide that has been proposed as a promising biomaterial in tissue engineering and bone regeneration, due to its ability to stimulate the recruitment and adhesion of osteogenic progenitor cells. The aim of our preliminary study was to evaluate, by micro-computed tomography (micro-CT), the osseointegration and bone formation around Cht-coated implants and to compare them with conventional surface-etched implants (SLA type). Four im-plants (8.5 mm length × 3.5 mm Ø) per hemiarch, were inserted into the jaws of five dogs, divided into two groups: chitosan-coated implant group (ChtG) and control group (CG). Twelve weeks after surgery, euthanasia was performed, and sectioned bone blocks were obtained and scanned by micro-CT and two bone parameters were measured: bone in contact with the implant surface (BCIS) and peri-implant bone area (PIBA). For BCIS and PIBA statistically significant values were obtained for the ChtG group with respect to CG (p = 0.005; p = 0.014 and p < 0.001 and p = 0.002, respectively). The results, despite the limitations, demonstrated the usefulness of chitosan coatings. However, studies with larger sample sizes and adequate experimental models would be necessary to confirm the results.

Evaluation of the Relationship between the Weight and Height Percentiles and the Sequence and Chronology of Eruption in Permanent Dentition.

The standard eruption of the permanent dentition in growing patients is influenced by multiple environmental factors. The objective of this research was to study the relationship between height and weight percentiles and the eruption of the permanent dentition. The design of the study was transversal based on the review of the clinical history, visual dental inspection, weight and height indicators, and their respective percentiles in patients in the mixed and definitive dentition stage. The descriptive and comparative analysis of the data was carried out with the statistical software R version 4.1.1. The sample size was 725 participants. The mean age of eruption of the first tooth was 8.0. The eruption sequence in the upper arch was first molar, central and lateral incisor, first premolar, canine, second premolar, and second molar. In the lower arch, the eruption sequence was: central incisor, first molar, lateral incisor, canine, first and second premolar, and second molar. The most frequent weight percentile was P50-97 (50.34%) and height P3-50 (53.38%). Weight (0.0129; 0.0426; 0.0495; 0.000166) and height (0.00768; 0.00473; 0.00927; 10-5) variables significantly influenced dental eruption. The factor that most influences the eruption of the permanent dentition is the height percentile.

Evaluation of the Relationship between the BMI and the Sequence and Chronology of Eruption in Permanent Dentition in Spanish Population.

The aim was to analyze the relationship between BMI (body mass index) and the sequence and chronology of the eruption of permanent teeth in a sample of Spanish children. Methods: The study design was descriptive, cross-sectional, observational, and epidemiological. Patients of pediatric age were included. Emerged teeth, and patient's age, race, and sex were recorded. The nutritional status of the child was assessed by calculating the BMI, according to the WHO parameters. Statistical analysis was carried out with a confidence interval of 95%. A prediction model with logistic regression models was obtained. Results: A total of 725 pediatric patients between 4 and 14 years old were analyzed. BMI acts as a predictor variable for eruption symmetry, as it was most frequent in overweight children (p < 0.001). The probability of symmetry in dental eruption increases for South American children, for an extra month of age, and each meter of height. BMI had an influence in the first tooth to appear only in the fourth quadrant. BMI did not seem to influence present teeth, and the sequence of permanent dental eruption was not influenced by the BMI category. Conclusions: Age, weight, height, and BMI act as significant predictors for eruption symmetry. BMI does not produce alterations in the eruption sequence of the permanent dentition.