Sellado marginal aplicando hipoclorito de sodio versus ácido fosfórico como acondicionador dental / Marginal sealing applying sodium hypochlorite versus phosphoric acid as dental conditioner

RESUMEN Introducción: La microfiltración es uno de los problemas principales de todas las obturaciones a base de resina. Muchos estudios buscan optimizar un buen sellado marginal utilizando diversos acondicionadores, como el hipoclorito de sodio, que permite que el adhesivo penetre bien, al generar desproteinización, y el ácido fosfórico que permite remover el barro dentinario, y así de esta manera formar una capa híbrida al colocar el adhesivo. Objetivo: Evaluar el grado de sellado marginal de la resina Bulk Fill aplicando gel de hipoclorito de sodio 10 por ciento comparado con el gel de ácido fosfórico al 37 por ciento en el acondicionamiento dental in vitro. Métodos: El universo fue de 72 dientes con cavidades clase I; se separaron en 4 grupos por muestra de 18 dientes cada uno; después de obturar se realizó el termociclaje a 500 ciclos entre 5 °C a 55 °C; luego se sumergieron en azul de metileno 2 por ciento, durante 12 h y 24 h a temperatura de 37 °C. Finalmente se evaluó el sellado marginal en el estereomicroscopio, según el ISO / TS 11405: 2015, con los criterios siguientes: grado 0 (sin microfiltración), grado 1 (microfiltración hasta esmalte), grado 2 (microfiltración hasta dentina) y grado 3 (microfiltración hasta piso pulpar). Resultados: El acondicionamiento con ácido fosfórico 37 por ciento a las 12 h presentó grado 0 (55,6 por ciento) y grado 1 (33,3 por ciento), y a las 24 h, grado 1 (55,6 por ciento). Con respecto al hipoclorito de sodio 10 por ciento a las 12 h, grado 0 (44.4 por ciento) y a las 24 h predominó grado 1 (55,6 por ciento). Para la contrastación de hipótesis en muestras relacionadas se obtuvo en ácido fosfórico 37 por ciento e hipoclorito de sodio al 10 por ciento a las 12 h y 24 h un p= 0,052 y p= 0,584, respectivamente. Para comparaciones entre muestras independientes a las 12 h y 24 h se obtuvo p= 0,462 y p= 0,406, respectivamente. Conclusiones: El gel de hipoclorito de sodio al 10 por ciento presenta similar eficacia en el sellado marginal respecto al gel de ácido fosfórico al 37 por ciento, al utilizarlo como acondicionador dental(AU)

ABSTRACT Introduction: Microfiltration is one of the main problems of all resin sealings. Many studies aim to optimize marginal sealing using a variety of conditioners, such as sodium hypochlorite, which allows good penetration of the adhesive by generating deproteinization, and phosphoric acid, which allows removal of the dental smear layer, thus creating a hybrid layer when the adhesive is placed. Objective: Evaluate the marginal sealing degree of Bulk Fill resin applying 10 percent sodium hypochlorite gel versus 37 percent phosphoric acid gel in in vitro dental conditioning. Methods: The study universe was 72 teeth with class I cavities, divided into four groups of 18 teeth. Upon sealing, thermal cycling was performed at 500 cycles from 5 ºC to 55 ºC. Next the teeth were submerged in 2 percent methylene blue for 12 h and 24 h at a temperature of 37 ºC. Finally marginal sealing was evaluated in the stereo microscope according to ISO / TS 11405: 2015, using the following scale: grade 0 (no microfiltration), grade 1 (microfiltration as far as the enamel), grade 2 (microfiltration as far as the dentin), and grade 3 (microfiltration as far as the pulp floor). Results: Conditioning with 37 percent phosphoric acid was grade 0 (55.6 percent) and grade 1 (33.3 percent) at 12 h, and grade 1 (55.6 percent) at 24 h, whereas conditioning with 10 percent sodium hypochlorite was grade 0 (44.4%) at 12 h, and predominantly grade 1 (55.6 percent) at 24 h. Hypothesis contrast in related samples yielded 37 percent phosphoric acid and 10 percent sodium hypochlorite at 12 h and 24 h, p= 0.052 and p= 0.584, respectively. Comparison between independent samples at 12 h and 24 h yielded p= 0.462 and p= 0.406, respectively. Conclusions: The 10 percent sodium hypochlorite gel has similar marginal sealing effectiveness as the 37 percent phosphoric acid gel when used as dental conditioners(AU)

Intracellular metabolism and potential cardiotoxicity of a ß-D-2'-C-methyl-2,6-diaminopurine ribonucleoside phosphoramidate that inhibits hepatitis C virus replication.

ß-D-2'-C-Methyl-2,6-diaminopurine ribonucleoside (2'-C-Me-DAPN) phosphoramidate prodrug (DAPN-PD) is a selective hepatitis C virus inhibitor that is metabolized intracellularly into two active metabolites: 2'-C-Methyl-DAPN triphosphate (2'-C-Me-DAPN-TP) and 2'-C-methyl-guanosine 5'-triphosphate (2'-C-Me-GTP). BMS-986094 and IDX-184 are also bioconverted to 2'-C-Me-GTP. A phase IIb clinical trial with BMS-986094 was abruptly halted due to adverse cardiac and renal effects. Herein, we developed an efficient large scale synthesis of DAPN-PD and determined intracellular pharmacology of DAPN-PD in comparison with BMS-986094 and IDX-184, versus Huh-7, HepG2 and interspecies primary hepatocytes and human cardiomyocytes. Imaging data of drug treated human cardiomyocytes was found to be most useful in determining toxicity potential as no obvious beating rate change was observed for IDX-184 up to 50 µM up at 48 h. However, with BMS-986094 and DAPN-PD at 10 µM changes to both beat rate and rhythm were noted.

Phase I Study of CTT1057, an 18F-Labeled Imaging Agent with Phosphoramidate Core Targeting Prostate-Specific Membrane Antigen in Prostate Cancer.

Agents targeting prostate-specific membrane antigen (PSMA) comprise a rapidly emerging class of radiopharmaceuticals for diagnostic imaging of prostate cancer. Unlike most other PSMA agents with a urea backbone, CTT1057 is based on a phosphoramidate scaffold that irreversibly binds to PSMA. We conducted a first-in-humans phase I study of CTT1057 in patients with localized and metastatic prostate cancer. Methods: Two patient cohorts were recruited. Cohort A patients had biopsy-proven localized prostate cancer preceding radical prostatectomy, and cohort B patients had metastatic castration-resistant prostate cancer. Cohort A patients were imaged at multiple time points after intravenous injection with 362 ± 8 MBq of CTT1057 to evaluate the kinetics of CTT1057 and estimate radiation dose profiles. Mean organ-absorbed doses and effective doses were calculated. CTT1057 uptake in the prostate gland and regional lymph nodes was correlated with pathology, PSMA staining, and the results of conventional imaging. In cohort B, patients were imaged 60-120 min after injection of CTT1057. PET images were assessed for overall image quality, and areas of abnormal uptake were contrasted with conventional imaging. Results: In cohort A (n = 5), the average total effective dose was 0.023 mSv/MBq. The kidneys exhibited the highest absorbed dose, 0.067 mGy/MBq. The absorbed dose of the salivary glands was 0.015 mGy/MBq. For cohort B (n = 15), CTT1057 PET detected 97 metastatic lesions, and 44 of 56 bone metastases detected on CTT1057 PET (78.5%) were also detectable on bone scanning. Eight of 32 lymph nodes positive on CTT1057 PET (25%) were enlarged by size criteria on CT. Conclusion: CTT1057 is a promising novel phosphoramidate PSMA-targeting 18F-labeled PET radiopharmaceutical that demonstrates similar biodistribution to urea-based PSMA-targeted agents, with lower exposure to the kidneys and salivary glands. Metastatic lesions are detected with higher sensitivity on CTT1057 imaging than on conventional imaging. Further prospective studies with CTT1057 are warranted to elucidate its role in cancer imaging.

White spot lesions: Does etching really matter?

AIM: The clinical significance of acid etching prior to orthodontic bonding is controversial. In the present study, we evaluated the effect of 15 seconds of acid etching on enamel demineralization. METHODS: Twenty-seven human molars were sectioned and assigned to two groups. Under standardized conditions, the enamel surfaces were imaged using FluoreCam to obtain baseline data. Group 1 was etched using 37% phosphoric acid for 15 seconds, rinsed with water, and then imaged again; group 2 was only rinsed with water. Water rinse was collected for calcium chemical analysis using inductively-coupled plasma auger electron spectrometry. Both groups were subjected to 9 days of pH cycling, after which final FluoreCam images were obtained. RESULTS: Group 1 showed a significant increase in lesion area (P=.012), decrease in light intensity (P=.009), and decrease in impact (P=.007) after acid etching. The amount of calcium that leached out over the 15 seconds was 14 ppm ±2.4 (0.35 mmol/L±0.06). Following pH cycling, there was no statistically-significant between-group difference in overall enamel demineralization. CONCLUSION: Initial demineralization caused by 15 seconds of acid etching does not increase enamel susceptibility to further demineralization. This suggests that acid etching does not increase the risk of developing white spot lesions during orthodontics.

Nucleotide Substrate Specificity of Anti-Hepatitis C Virus Nucleoside Analogs for Human Mitochondrial RNA Polymerase.

Nucleoside analog inhibitors (NAIs) are an important class of antiviral agents. Although highly effective, some NAIs with activity against hepatitis C virus (HCV) can cause toxicity, presumably due to off-target inhibition of host mitochondrial RNA polymerase (POLRMT). The in vitro nucleotide substrate specificity of POLRMT was studied in order to explore structure-activity relationships that can facilitate the identification of nontoxic NAIs. These findings have important implications for the development of all anti-RNA virus NAIs.

Assessment of enamel cracks at adhesive cavosurface margin using three-dimensional swept-source optical coherence tomography.

OBJECTIVES: Swept-source optical coherence tomography (SS-OCT) can construct cross-sectional images of internal biological structures. The aim of this study was to evaluate enamel cracks at the cavosurface margin of composite restorations using SS-OCT. METHODS: Bowl-shaped cavities were prepared at two locations (mid-coronal and cervical regions) on the enamel surface of 60 bovine teeth. Half of the cavities (30) were treated with phosphoric acid gel. A two-step self-etch adhesive (Clearfil SE Bond) was applied to all cavities and a flowable composite was placed in bulk. After 7days in water at 37°C, three-dimensional (3D) images of the specimens were obtained using SS-OCT, and cross-sectional views of the cavosurface margin were examined. Presence and extent of enamel cracks along the cavosurface margin circumference were evaluated using a 5-point scale. The results were statistically compared with Wilcoxon rank sum test with Bonferroni correction. RESULTS: 3D SS-OCT could detect enamel cracks at the cavosurface margin of composite restorations. Cervical regions caused more enamel cracking than mid-coronal regions. Phosphoric acid etching increased the incidence of enamel cracks compared with the preparations without etching. CONCLUSION: SS-OCT can be used to detect enamel cracks at the margins of composite restorations noninvasively. Presence and extent of enamel cracks depended on the enamel region and bonding protocol. CLINICAL SIGNIFICANCE: SS-OCT can be used to detect enamel cracks at the margins of composite restorations noninvasively. Selective phosphoric acid etching of the enamel significantly increased the incidence of marginal cracks, especially in cervical preparation.

Effect of a novel quaternary ammonium silane on dentin protease activities.

OBJECTIVES: Demineralized dentin collagen release C-terminal cross-linked telopeptide (ICTP) and C-terminal peptide (CTX) during degradation. The present study evaluated the effects of dentin pre-treatment with K21, a quaternary ammonium silane (QAS), on matrix metalloproteinase (MMP) and cathepsin K-mediated collagen degradation. METHODS: Dentin beams were demineralized with 10% H3PO4 for 24h. After baseline dry mass measurements, the beams were divided into 5 groups (N=10) according to protease inhibitors. The beams were pre-treated for 2min with 2% chlorhexidine (CHX), 2%, 5% or 10% QAS; no pre-treatment was performed for the control group. The beams were subsequently incubated in calcium- and zinc-containing medium for 3, 7 or 14days, after which changes in dry mass were measured and incubation media were examined for ICTP and CTX release. The MMP-2 and cathepsin K activities in QAS-treated dentin powder were also quantified using ELISA. RESULTS: The two factors (disinfectants and time) had a significant effect on dry mass loss, ICTP and CTX release (p<0.001). The percentage of dry mass loss increased with time and was significantly lower in all experimental groups when compared to the control at 14days (p<0.001). Conversely, the rate of ICTP and CTX release was significantly lower in the experimental groups, compared to the uninhibited control at 7 and 14days (p<0.001). Dentinal MMP-2 and cathepsin K activities were significantly reduced after demineralized dentin was pre-treated with QAS. CONCLUSION: The experimental QAS is a good inhibitor of MMP and cathepsin K activities in demineralized dentin. CLINICAL SIGNIFICANCE: The newly developed antibacterial quaternary ammonium silane increases the resistance of dentin collagen to degradation by inhibiting endogenous matrix metalloproteinases and cysteine cathepsins. The quaternary ammonium silane cavity disinfectant is promising for use as a protease inhibitor to improve durability of resin-dentin bonds.

Vibrational monitor of early demineralization in tooth enamel after in vitro exposure to phosphoridic liquid.

The Raman spectroscopic method has been applied to quantitatively assess the in vitro degree of demineralization in healthy human teeth. Based on previous evaluations of Raman selection rules (empowered by an orientation distribution function (ODF) statistical algorithm) and on a newly proposed analysis of phonon density of states (PDOS) for selected vibrational modes of the hexagonal structure of hydroxyapatite, a molecular-scale evaluation of the demineralization process upon in vitro exposure to a highly acidic beverage (i.e., CocaCola™ Classic, pH=2.5) could be obtained. The Raman method proved quite sensitive and spectroscopic features could be directly related to an increase in off-stoichiometry of the enamel surface structure since the very early stage of the demineralization process (i.e., when yet invisible to other conventional analytical techniques). The proposed Raman spectroscopic algorithm might possess some generality for caries risk assessment, allowing a prompt non-contact diagnostic practice in dentistry.

NaF Inhibits Matrix-Bound Cathepsin-Mediated Dentin Matrix Degradation.

Matrix metalloproteinases (MMPs) and cysteine cathepsins (CCs) degrade the collagen fibrils of demineralized dentin. Sodium fluoride (NaF) has previously been shown to inhibit recombinant MMP-2 and MMP-9. This study aimed to evaluate the efficacy of NaF on the inhibition of dentin-bound MMPs and CCs. Dentin beams were completely demineralized in 10% phosphoric acid. The baseline total MMP activity and dry masses were measured. Beams were assigned to test groups based on similar MMP activity and dry mass (n = 10/group), and incubated in artificial saliva (control) or artificial saliva with NaF containing 6-238 mM fluoride for 1, 7 and 21 days. The dry mass loss and MMP activities were reassessed at each time point. The proteolytic activity was screened by gelatin zymography. ICTP and CTX released to the incubation medium were analyzed as indices of MMP and cathepsin K activity, respectively. The beams were examined under scanning electron microscopy. All NaF doses reduced the dry mass loss after 21 days (p < 0.05). NaF inhibition of the total MMP activity ranged between 5 and 80%. In gelatin zymography, the bands of MMP-2 and MMP-9 became less prominent with increasing NaF levels. NaF did not decrease the released ICTP (p > 0.05). Less CTX release was detected with F ≥179 mM (p < 0.05). CaF2-like minerals were observed on the beams. High levels of NaF may slow the degradation of the dentin matrix due to the inhibition of cathepsin K. Fluoride does not seem effective in the direct inhibition of proteolysis by dentin matrix-bound MMPs.

[Increased susceptibility for white spot lesions by surplus orthodontic etching exceeding bracket base area]. / Prédisposition aux leucomes pré-carieux due à un excès de mordançage autour des attaches orthodontiques∗.

INTRODUCTION: There is a paucity of information with regard to the susceptibility of iatrogenic white spot lesion formation after inattentive, surplus orthodontic etching with 30% phosphoric acid and the subsequent provision or absence of adequate oral hygiene. METHODS: Ninety sound enamel specimens were randomly allocated to 6 trial groups (N = 15 each) for etching with 30% phosphoric acid for either 15 seconds and standardized daily enamel brushing or no brushing, etching for 30 seconds with daily brushing or no brushing, or nonetched controls with brushing or no brushing. Nutritive acidic assaults were simulated by demineralization cycles 3 times per day for 1 hour with interim storage in artificial saliva. Lesion depths in terms of percentage of fluorescence loss (delta F, delta Q) and lesion extension compared with the baseline were assessed by using quantitative light-induced fluorescence after 2, 7, 14, 21, and 42 days. Etching duration, trial time elapse, and oral hygiene, as well as the significance of factor interactions, were analyzed with 3-way analysis of variance (α=5%). RESULTS: The impact of the factors of enamel brushing, trial time elapse, and etching each had a comparably significant effect on lesion progression. The effect of surplus etching on white spot lesion formation was significantly enhanced by the simultaneous absence of enamel brushing and also the progression of trial time. The combination of 30 seconds of surplus etching with inadequate oral hygiene was especially detrimental. CONCLUSIONS: Excessive surplus orthodontic etching of the complete labial enamel surface, instead of the bracket bases only, must be avoided to prevent iatrogenic white spot lesions. Etching times not exceeding 15 seconds are favorable.

Development and characterization of chemical cochleostomy in the Guinea pig.

OBJECTIVES: Creation of an atraumatic, hearing-preservation cochleostomy is integral to the future of minimally invasive inner ear surgery. The goal of this study was to develop and characterize a novel chemical approach to cochleostomy. STUDY DESIGN: Prospective animal study. SETTING: Laboratory. METHODS: Experimental animal study in which phosphoric acid gel (PAG) was used to decalcify the otic capsule in 25 Hartley guinea pigs. Five animals in each of 5 surgical groups were studied: (1) mechanically opening the auditory bulla alone, (2) PAG thinning of the basal turn otic capsule, leaving endosteum covered by a layer of bone, (3) micro-pick manual cochleostomy, (4) PAG chemical cochleostomy, exposing the endosteum, and (5) combined PAG/micro-pick cochleostomy, with initial chemical thinning and subsequent manual removal of the last osseous layer. Preoperative and postoperative auditory brainstem responses and otoacoustic emissions were obtained at 2, 6, 10, and 16 kHz. Hematoxylin and eosin-stained paraffin sections were compared. RESULTS: Surgical and histologic findings confirmed that application of PAG provided reproducible local bone removal, and cochlear access was enabled. Statistically significant auditory threshold shifts were observed at 10 kHz (P = .048) and 16 kHz (P = .0013) following cochleostomy using PAG alone (group 4) and at 16 kHz using manual cochleostomy (group 3) (P = .028). No statistically significant, postoperative auditory threshold shifts were observed in the other groups, including PAG thinning with manual completion cochleostomy (group 5). CONCLUSION: Hearing preservation cochleostomy can be performed in an animal model using a novel technique of thinning cochlear bone with PAG and manually completing cochleostomy.

Suicide case due to phosphoric acid ingestion: case report and review of literature.

Ingesting caustic substances represents a common event which may result in serious injuries of the gastrointestinal system. Severity of injury depends on the type of ingested substance: Caustic burns are more frequently associated with acid ingestion and their severity depends on type, concentration, time of exposure, and amount of the ingested substance. We report a case of phosphoric acid ingestion leading to death in a patient with depressive disorder. While reports ingestion of other acids and organophosphates can be found in the literature, there are no reports detailing a death due to phosphoric acid ingestion. We hope that presenting the findings in this case can aid death investigators in future cases that may involve ingestion of such a substance. After autopsy pH, phosphate and calcium ions concentration in the blood were analyzed. The cause of death was due to systemic effects: metabolic acidosis, hypophosphatemia, hypocalcemia, and hyperkalemia.

Enamel prism-like tissue regeneration using enamel matrix derivative.

BACKGROUNDS: Enamel matrix derivative (EMD) has been shown to promote periodontal regeneration, but its effect on biomimetic mineralisation of enamel is not reported. OBJECTIVES: This in vitro study aimed to investigate the effect of commercially available EMD on promoting biomimetic mineralisation in demineralised enamel using an agarose hydrogel model. METHODS: Human enamel slices were demineralised with 37% phosphoric acid for 1 min. They were covered with a 2-mm-thick EMD-calcium chloride (CaCl2) agarose hydrogel. Another 2-mm-thick ion-free agarose hydrogel was added on top of the EMD-CaCl2 hydrogel. They were incubated in a phosphate solution containing fluoride at 37°C for 96 h. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD) were used to evaluate the crystals formed on the demineralised enamel surface. A nano-indenter was used to evaluate the elastic modulus and nanohardness on the surface of the enamel slices. RESULTS: SEM observed enamel prism-like crystals formed on the enamel. They had typical apatite hexagonal structures, which corroborated the enamel's microstructure. EDX revealed that the elements were predominantly calcium, phosphorus, and fluorine. XRD confirmed that they were fluorinated hydroxyapatite. The mean elastic modulus before and after remineralisation was 59.1GPa and 78.5GPa (p<0.001), respectively; the mean nanohardness was 1.1GPa and 2.2GPa, respectively (p<0.001). CONCLUSIONS: EMD promoted in vitro biomimetic mineralisation and facilitated enamel prism-like tissue formation on demineralised human enamel. CLINICAL SIGNIFICANCE: This study is the first to report on using EMD in biomimetic mineralisation, which may serve as a biomaterial for enamel repair.

Possible ways of reducing dental erosive potential of acidic beverages.

Frequent consumption of acidic beverages is related to excessive tooth wear, namely dental erosion. Preventive measures may involve reduction or elimination of acidic drink consumption. However, the success of this approach is difficult to achieve as it is highly dependent on patient compliance. Therefore, a practical way of minimizing the erosive potential of popular acidic drinks may be their chemical modification. The aim of this article was to review the different methods of modification and their shortcomings. The available literature demonstrates that the erosive potential of most acidic beverages could be reduced. To date, the effectiveness of soluble calcium salts supplementation is the best established. However, modification can reduce the sensorial quality of the drink and shorten its shelf-life. There is also a need to evaluate the lowest effective and safe dose of the additive.

Zinc induces apatite and scholzite formation during dentin remineralization.

The aim of this study was to ascertain whether zinc may improve the repair ability of demineralized dentin. Dentin disks were demineralized by phosphoric acid during 15 s and immersed in artificial saliva, remineralizing solution, a zinc chloride solution and a zinc oxide solution. Dentin specimens were analyzed after 24 h and 1 month of storage. Surface morphology was assessed by atomic force and scanning electron microscopy, mechanical properties were analyzed by nanohardness testing in a TriboIndenter, and chemical changes at the surfaces were determined by X-ray diffraction, Raman and energy-dispersive elemental analyses. After phosphoric acid application, dentin was only partially demineralized. Demineralized dentin was remineralized after 24 h of storage in any of the tested solutions (nanohardness increased and hydroxylapatite formation was detected by Raman). Remineralization was maintained up to 1 month in dentin stored in remineralizing solution, zinc chloride and zinc oxide. Zinc and phosphate were important for hydroxylapatite homeostasis. Scholzite formation was encountered in dentin stored in zinc-containing solutions. Zinc might allow to reach the balance between dentin demineralization and remineralization processes.

Early dentine remineralisation: morpho-mechanical assessment.

OBJECTIVES: The purpose of this study was to evaluate some physical-mechanical and morphological changes of demineralised dentine at early stages of dentine remineralisation. METHODS: Extracted human third molars were sectioned to obtain dentine discs. After polishing the dentine surfaces, three groups were established: (1) untreated dentine - UD, (2) 37% phosphoric acid application for 15s (partially demineralised dentine - PDD) and (3) 10% phosphoric acid for 12h, at 25°C (totally demineralised dentine - TDD). Five different remineralizing fluids were used for 30min: chlorhexidine (CHX), artificial saliva (AS), phosphated solution (PS), ZnCl2 and ZnO solutions. Atomic force microscopy (AFM) imaging/nano-indentation, surface nano-roughness and fibrils diameter were determined. X-ray diffraction (XRD), energy dispersive elemental analyses (EDX) and high resolution scanning electron microscopy analysis (HRSEM) were applied. RESULTS: PDD and TDD preserved some mineral contents. After demineralisation and immersion in all solutions, width of nanomechanical properties and fibrils was increased, and total nanoroughness was decreased. Peritubular and intertubular dentine were remineralised. CONCLUSION: Mineral exists in PA-demineralised dentine matrix and it is important since it may work as a constant site for further nucleation. The dentine surface remineralisation process may be stimulated as early as 30min in abiotic conditions, with a pH ranging from 7.0 to 7.5. CLINICAL SIGNIFICANCE: The existence of enzymes and remineralising factors within the dentine matrix may facilitate early dentine remineralisation under favourable conditions. This process should be stimulated by new reparative materials.

Oral tissues and orthodontic treatment: common side effects.

The aim of this paper was to provide a literature review about the problems that can occur during orthodontic treatment. Using the PubMed database we collected items that would provide information regarding the direct consequences of the placement of an orthodontic appliance: coming to the discussion of the following topics: candida infections, the effects on the soft tissues, the effects on periodontal tissues and effects on hard tissues. The presence of appliances in the oral cavity increases the prevalence of people with candida, specifically the species Candida Albicans is the most frequently isolated. The balance between the clearance of the microorganism, the colonization and the state of candidiasis depends both on the virulence of the fungus, and the competence of the host immune system. On soft tissues, cases of ulceration of the upper jaw by a rapid palatal expander and pyogenic granuloma due to quad helix appliance have been reported. The second one is mostly observed on vestibular gingiva. The first one was found, however, in patients suffering from diabetes mellitus type 1 because of the tissue modifications induced by this pathological condition. The more severe periodontic effects are those caused by incorrect use of orthodontic elastic separators. Finally, the White Spot Lesions are the direct consequences of a wrong conditioning of enamel when attaching the bracket. They represent a first stage of caries in the positioning area of the bracket. The orthodontist is required to intercept these issues not to affect the success of the treatment.

Multiscale characterization of partially demineralized superficial and deep dentin surfaces.

The objective of this study was to address the following question: 'Which properties are modified in partially demineralized surfaces, compared with non-demineralized dentin surfaces, following orthophosphoric acid-etching as performed in clinical procedures?'. For this purpose, the complementary techniques atomic force microscopy/spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and contact angle measurements were used to provide a multiscale characterization of the dentin substrate undergoing the acidic preconditioning designed to enhance wetting. Special attention was given to the influence of the etching pretreatment on the nanomechanical properties at different levels of dentin surfaces, in both dry and hydrated conditions. The four-sided pyramid model (extended Hertz contact model) proved to be accurate for calculating the apparent Young's modulus, offering new information on the elasticity of dentin. The modulus value notably decreased following etching and surface hydration. This study underlines that after the acid etching pretreatment the contribution of the nanomechanical, morphological, and physicochemical modifications has a strong influence on the dentin adhesion properties and thus plays a significant role in the coupling of the adhesive-resin composite build-up material at the dentin surface.