Protective effect of various toothpastes and mouthwashes against erosive and abrasive challenge on eroded dentin: an in vitro study

The study aimed to compare various toothpastes and mouthwashes on permanent tooth dentin after erosive and abrasive challenges. 130 sound premolars dentin were randomly submitted to an initial erosive challenge and a cycle of erosive and abrasive challenges for five days. The five experimental groups (n = 26) were: (1) Control group (artificial saliva), (2) Elmex erosion protection toothpaste and mouthwash, (3) Vitis anticaries biorepair toothpaste and mouthwash, (4) Oral B Pro-expert toothpaste and Oral B Fluorinse mouthwash, and (5) MI Paste ONE toothpaste and Caphosol mouthwash. Microhardness, surface roughness values, and the topographical characteristics of the dentin surface were assessed. The highest percentage of recovered dentin microhardness (%RDMH) value was observed in groups 2 and 4, followed by groups 5 and 3, respectively. The %RDMH values in groups 2 and 4 did not demonstrate a significant difference (p = 0.855). The highest percentage of improvement in surface roughness was recorded in groups 2 and 4, with no significant differences (p = 0.989). The atomic force microscopy (AFM) findings were consistent with the surface roughness data. The best recovery of dentin microhardness and roughness were measured with the Elmex and Oral B toothpaste and mouthwash, followed by MI Paste ONE toothpaste and Caphosol mouthwash and Vitis anticaries biorepair toothpaste and mouthwash.

Preparation and characterization of a nanohydroxyapatite and sodium fluoride loaded chitosan-based in situ forming gel for enamel biomineralization

The development of remineralizing smart biomaterials is a contemporary approach to caries prevention. The present study aimed at formulation preparation and characterization of a thermoresponsive oral gel based on poloxamer and chitosan loaded with sodium fluoride (NaF) and nanohydroxyapatite (nHA) to treat demineralization. The chemical structure and morphology of the formulation were characterized using FTIR and FESEM-EDS tests. Hydrogel texture, rheology, and stability were also examined. The hydrogel was in a sol state at room temperature and became gel after being placed at 37 °C with no significance different in gelation time with the formulation without nHA and NaF as observed by t-test. The FTIR spectrum of nHA/NaF/chitosan-based hydrogel indicated the formation of physical crosslinking without any chemical interactions between the hydrogel components. The FESEM-EDS results demonstrated the uniform distribution of each element within the hydrogel matrix, confirming the successful incorporation of nHA and NaF in the prepared gel. The hardness, hydrogel's adhesiveness, and cohesiveness were 0.9 mJ, 1.7 mJ, and 0.37, respectively, indicating gel stability and the acceptable retention time of hydrogels. The formulation exhibited a non-Newtonian shear-thinning pseudoplastic and thixotropic behavior with absolute physical stability. Within the limitation of in vitro studies, nHA/NaF/chitosan-based in situ forming gel demonstrated favorable properties, which could be trasnsorm into a gel state in oral cavity due to poloxamer and chitosan and can prevent dental caries due to nHA and NaF. We propose this formulation as a promising dental material in tooth surface remineralization.

Evaluation of bleaching agent effects on color and microhardness change of silver diamine fluoride-treated demineralized primary tooth enamel: An in vitro study

Background

The present study aimed to assess the impact of application of fluoridated- 10% carbamide peroxide (CP) with or without potassium iodide (KI) on silver diamine fluoride (SDF)-treated enamel surface in the primary teeth.

Methods

After stained-remineralized caries lesions (s-RCLs) creation, 96 teeth were randomly allocated to four experimental groups: Group 1:SDF-treated enamel followed by 8-h/day application of 10% CP for 2 weeks; Group 2: SDF-treated enamel followed by 15-min/day application of 10% CP for 3 weeks; Group 3: SDF + KI-treated enamel followed by 8-h/day application of 10% CP for 2 weeks; and Group 4: SDF + KI-treated enamel followed by 15-min/day application of 10% CP for 3 weeks. Enamel microhardness (EMH) test (n = 12) and spectrophotometric color assessment (n = 12) was performed at four stages: baseline (intact enamel), demineralized enamel, aged remineralized-stained enamel, and after final intervention. Sixteen samples were used for SEM evaluation. Data were analyzed with the paired t-test, one-way ANOVA, and Tukey’s post-hoc test (p < 0.05).

Results

EMH values in all groups showed significant decrease after demineralization (all, p < 0.00001). All samples showed complete recovery of EMH values (%REMH) after SDF application compared to demineralization (%REMH_SDF) (p = 0.971). Bleaching caused a slight decrease in %REMH for all groups. However, the differences were not statistically significant (p = 0.979). SEM findings revealed no changes in enamel porosity after bleaching. Bleaching application ameliorated the discoloration in all groups (all, p < 0.00001). All samples in Groups 2 and 4 had significantly lighter color after 21 days as compared to 14-day exposure to the bleaching material (both, p < 0.00001).

Conclusions

SDF application on demineralized primary tooth enamel completely recovered enamel microhardness. 10% carbamide peroxide effectively bleached SDF stain without causing significant decrease in EMH values. Color improvement was more evident with the use of KI immediately after SDF application. Both 15-min and 8-h application of fluoridated CP resulted in statistically similar color enhancement in primary teeth.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-022-02371-3.

Particle Size, Mass Concentration, and Microbiota in Dental Aerosols

Many dental procedures are considered aerosol-generating procedures that may put the dental operator and patients at risk for cross-infection due to contamination from nasal secretions and saliva. This aerosol, depending on the size of the particles, may stay suspended in the air for hours. The primary objective of the study was to characterize the size and concentrations of particles emitted from 7 different dental procedures, as well as estimate the contribution of the nasal and salivary fluids of the patient to the microbiota in the emitted bioaerosol. This cross-sectional study was conducted in an open-concept dental clinic with multiple operators at the same time. Particle size characterization and mass and particle concentrations were done by using 2 direct reading instruments: Dust-Trak DRX (Model 8534) and optical particle sizer (Model 3330). Active bioaerosol sampling was done before and during procedures. Bayesian modeling (SourceTracker2) of long-reads of the 16S ribosomal DNA was used to estimate the contribution of the patients’ nasal and salivary fluids to the bioaerosol. Aerosols in most dental procedures were sub-PM₁ dominant. Orthodontic debonding and denture adjustment consistently demonstrated more particles in the PM₁, PM_2.5, PM₄, and PM₁₀ ranges. The microbiota in bioaerosol samples were significantly different from saliva and nasal samples in both membership and abundance (P < 0.05) but not different from preoperative ambient air samples. A median of 80.15% of operator exposure was attributable to sources other than the patients’ salivary or nasal fluids. Median operator’s exposure from patients’ fluids ranged from 1.45% to 2.75%. Corridor microbiota showed more patients’ nasal bioaerosols than oral bioaerosols. High-volume saliva ejector and saliva ejector were effective in reducing bioaerosol escape. Patient nasal and salivary fluids are minor contributors to the operator’s bioaerosol exposure, which has important implications for COVID-19. Control of bioaerosolization of nasal fluids warrants further investigation.

Remineralization effects of self-assembling peptide P11 -4 associated with three materials on early enamel carious lesions: An in vitro study

The aim of this study was to assess the remineralization of enamel caries lesions using the self-assembling peptide P11 -4 associated with different materials. Artificial early enamel lesions were prepared on 154 primary teeth. The samples were randomly divided into eight groups: (1) control, (2) P11 -4, (3) fluoridate toothpaste (FT), (4) P11 -4 + FT, (5) casein phosphopeptide-amorphous calcium phosphate (CPP-ACP), (6) P11 -4 + CPP-ACP, (7) fluoridate bioactive glass toothpaste (BT), and (8) P11 -4 + BT. The surface enamel microhardness (EMH) and energy-dispersive X-ray spectroscopy (EDS) of the teeth were then measured at the baseline, after demineralization, and after 28 days of remineralization. The enamel surfaces were assessed by field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). The data were analyzed with one-way analysis of variance (ANOVA) (p < .05). EMH after demineralization was significantly lower than the baseline value (p < .001). The interventions led to an enhanced percentage of EMH recovery (%REMH), which was higher in Groups 6 and 7. There was no significant difference between Groups 3 and 4. Groups 1 and 2 had the lowest %REMH. The mean calcium/phosphate weight percentage ratio of P11 -4 was significantly lower than the others (p < .001). The FESEM and AFM images revealed mineral deposition on the eroded enamel and reductions in surface roughness in Groups 5 and 7.

Adhesion of three types of fissure sealant in saliva-contaminated and noncontaminated conditions: an in vitro study

PURPOSE

To evaluate the proportion of microleakage (PM), shear bond strength (SBS), and the fissure sealant (FS) interface by scanning electron microscopy (SEM) in three kinds of FS when the enamel surfaces were contaminated with saliva.

METHODS

198 sound third molar teeth were randomly divided into three pretreatment condition groups (n = 66): dry, saliva contamination removed by cotton pellet, or saliva removed by air-drying. A resin-based FS (Clinpro™), amorphous calcium phosphate-containing FS (Aegis®), or glass ionomer-based FS (Fuji Triage®) was applied on the treated enamel, and PM and SBS were assessed. Two specimens from each group were observed with SEM. p values < 0.05 was considered statistically significant.

RESULTS

Glass ionomer-based FS showed the highest PM in all three surface conditions (p values < 0.05 were considered statistically significant). No significant difference in PM was observed between resin-based FS and amorphous calcium phosphate-containing FS (p > 0.05). Resin-based FS showed significantly greater SBS in all three surface conditions compared to glass ionomer-based FS. SEM observations showed that saliva contamination led to gaps at the enamel-sealant interface.

CONCLUSION

Neither cotton pellet-drying nor air-drying effectively removed saliva from the contaminated enamel surface. Glass ionomer-based FS showed the highest PM and the lowest SBS in contaminated and noncontaminated conditions. The highest SBS was obtained with resin-based FS.

Drug Delivery Assessment of a Novel Triple Antibiotic-Eluting Injectable Platelet-Rich Fibrin Scaffold: An In Vitro Study

BACKGROUND

Intracanal disinfection is a critical, yet challenging goal for long-term success in regenerative-based treatments. This in-vitro study aimed to assess the release profile of triple antibiotic- eluting Injectable Platelet-Rich Fibrin (I-PRF) constructs in 28 days.

METHODS

I-PRF scaffolds containing triple antibiotic mixture [Metronidazole (MET), Ciprofloxacin (CIP), and Minocycline (MINO)] by immersion (group one), I-PRF scaffolds containing triple antibiotic mixture by integration (group two), and antibiotic-free I-PRF scaffolds (group three) were fabricated. The antibiotic release from the scaffolds was measured using High-Performance Liquid Chromatography (HPLC) (the mobile phase of 0.1% formic acid and methanol (35:65 v/v), a C18 analytical column (150 × 4.6 mm, 5 μm) at a flow rate of 0.7 mL/min, at 25ºC) at days 1, 3, 7, 14, 21, and 28.

RESULTS

Retention times for MINO, CIP, and MET were achieved as 2.3, 2.6, and 3.1 min, respectively. The maximum UV absorbance values for CIP, MET, and MINO were 268 nm, 278 nm, and 350 nm, respectively. The results of the first group showed burst release within the first 24 hours followed by sustained maintenance of all three antibiotics up to 14 days. MINO and MET were still detectable in the third week. The second group could not sustainably release the antibiotics.

CONCLUSION

The developed method for the simultaneous identification and quantification of each antibiotic in I-PRF was sensitive and quick. Overall, group one could take up the antibiotics in adequate quantities and then subsequently release them over the study period.

Ion release and recharge from a fissure sealant containing amorphous calcium phosphate

To assess- the release of calcium and phosphate ions from a fissure sealant containing amorphous calcium phosphate (ACP), and to determine the re-release capacity of these ions when charged with a solution containing casein phosphopeptide-amorphous calcium phosphate (CPP-ACP). Nine blocks of ACP resin-based sealant were prepared and immersed in three solutions at different pH (4.0, 5.5, 7.0), and calcium and phosphate ion release was measured with ion chromatography at 1, 3, 5, 7, 14, 21 and 28 days after immersion. Sixty days after immersion, each block was charged with CPP-ACP solution in three 7-day cycles to investigate the re-release of these ions, which was measured on days 1, 3, and 7. No difference was observed in initial calcium ion release at pH 4.0 and pH 5.5. At both values, ion release was significantly higher than at pH 7.0 (p<0.001). Initial phosphate release was significantly different among the three pH values (p<0.001). After re-charging the specimens, calcium ion re-release was greater than phosphate ion release. Initial ion release from ACP resin-based sealant was greatest at the lowest pH. Ion release decreased with time. As the number of recharge cycles increased, ion re-release also improved. Phosphate ion re-release required more recharge cycles than calcium ion re-release.

Onset and limiting amplitude of yaw instability of a submerged three-tethered buoy

In this paper the dynamics of a submerged axi-symmetric wave energy converter are studied, through mathematical models and wave basin experiments. The device is disk-shaped and taut-moored via three inclined tethers which also act as a power take-off. We focus on parasitic yaw motion, which is excited parametrically due to coupling with heave. Assuming linear hydrodynamics throughout, but considering both linear and nonlinear tether geometry, governing equations are derived in 6 degrees of freedom (DOF). From the linearized equations, all motions, apart from yaw, are shown to be contributing to the overall power absorption. At higher orders, the yaw governing equation can be recast into a classical Mathieu equation (linear in yaw), or a nonlinear Mathieu equation with cubic damping and stiffness terms. The well-known stability diagram for the classical Mathieu equation allows prediction of onset/occurrence of yaw instability. From the nonlinear Mathieu equation, we develop an approximate analytical solution for the amplitude of the unstable motions. Comparison with regular wave experiments confirms the utility of both models for making relevant predictions. Additionally, irregular wave tests are analysed whereby yaw instability is successfully correlated to the amount of parametric excitation and linear damping. This study demonstrates the importance of considering all modes of motion in design, not just the power-producing ones. Our simplified 1 DOF yaw model provides fundamental understanding of the presence and severity of the instability. The methodology could be applied to other wave-activated devices.

Effect of hydroxyapatite nanoparticles on enamel remineralization and estimation of fissure sealant bond strength to remineralized tooth surfaces: an in vitro study

Background

The management of noncavitated caries lesions before sealant therapy is a clinical challenge when the tooth needs sealant application. Sealing noncavitated carious lesions in pits and fissures may lead to failure of the fissure sealant (FS) due to incomplete sealing. Therefore the use of remineralizing agents such as nanoparticles has been suggested. This study investigated the ability of hydroxyapatite nanoparticles (nano-HA) to remineralize enamel, and their effect on sealant microleakage and shear bond strength (SBS).

Methods

A total of 192 third molars were demineralized and pretreated with two concentrations of nano-HA with and without sodium hexametaphosphate (SHMP), followed by phosphoric acid etching and resin FS application. The study groups were 1) etching + FS, 2) etching + nano-HA 0.15% + FS, 3) etching + nano-HA 0.03% + FS, 4) etching + mixture of nano-HA 0.15% and SHMP 0.05% + FS, 5) etching + mixture of nano-HA 0.03% + SHMP 0.01% + FS. The laboratory tests included microleakage in 50 teeth, scanning electron microscopy (SEM) evaluation in 10 samples, and SBS in 100 samples. Enamel remineralization changes were evaluated in 32 teeth with energy-dispersive X-ray spectroscopy (EDS) and field emission scanning electron microscope (FESEM).

Results

Nano-HA enhanced the SBS to remineralized enamel in a large percentage of nanoparticles. Mean SBS in group 2 was significantly greater than in groups 1, 3 and 4 (all P < 0.05). SBS was related to nano-HA concentration: nano-HA 0.15% yielded greater SBS (16.8 ± 2.7) than the 0.03% concentration (14.2 ± 2.1). However, its effect on microleakage was not significant. Nano-HA with or without SHMP led to enhanced enamel remineralization; however, the Calcium (Ca)/Phosphate (P) weight percent values did not differ significantly between the groups (P > 0.05). SEM images showed that SHMP did not affect sealant penetration into the deeper parts of fissures. FESEM images showed that adding SHMP led to increased nanoparticle dispersal on the tooth surface and less cluster formation.

Conclusions

The ultraconservative approach (combining nano-HA 0.15% and SHMP) and FS may be considered a minimal intervention in dentistry to seal demineralized enamel pits and fissures.

Prediction of dental arch width increase in the early mixed dentition using craniofacial parameters

BACKGROUND

The dimensions of the dental arch have considerable impact on treatment planning. Since the dental arch development has a relationship with the craniofacial growth, we designed a cohort study to find a regression model for predicting the mandibular arch width increase using craniofacial parameters.

METHODS

A total of 148 children, all in early mixed dentition, were selected randomly from primary schools by cluster sampling. Craniofacial anthropometric parameters were measured by a caliper bow and intercanine and intermolar widths were assessed on each subject's dental casts by a digital caliper at baseline and after 12 months. Data were analyzed with SPSS v. 15. Student's t-test and linear regression test were applied separately for girls and boys.

RESULTS

Out of 153 children, 148 returned for one-year follow-up meeting the inclusion criteria. The results of regression analysis showed a significant inverse correlation between intercanine width and facial index. The bigonial dimension showed a high correlation with both the intermolar width and the intercanine width increase.

CONCLUSIONS

We found that the arch width increase in the early mixed dentition could be predicted precisely based on certain craniofacial parameters.

A comparative evaluation of APF gel, CPP/ACP paste alone and in combination with carbon dioxide laser on human enamel resistance to acid solubility using atomic absorption spectrometry: an in-vitro study

BACKGROUND

The aim of this study was to compare the effects of acidulated phosphate fluoride (APF) gel, calcium phosphopeptide-amorphous calcium phosphate (CPP/ACP) paste alone and in combination with CO2 laser on the resistance of enamel to acid solubility.

METHODS

Ninety enamel sections were obtained from 15 extracted teeth and were randomly assigned to six groups: 1) control group; 2) APF group; 3) CPP-ACP group; 4) CO2 laser group; 5) APF + CO2 group; and 6) CPP-ACP + CO2 group. The specimens were individually demineralized in 0.1 M lactic acid solution with adjusted pH of 4.8 for 24h at 37 ºC. The acid solubility was determined using atomic absorption spectrometry. Statistical analysis was done using one-way ANOVA and Tukey-Kramer post hoc test (P<0.05).

RESULTS

The average extent of calcium ion released (ppm) was estimated as follow: group 1: 6.974±1.757, group 2: 5.363±1.383, group 3: 6.962±1.489, group 4: 6.890±1.560, group 5: 4.803±1.080 and group 6: 6.789±1.218. Based on the between-group comparison results, group 2 and group 5 showed significant differences with the other groups.

CONCLUSIONS

Under the studied conditions, only, the APF group alone and in combination with CO2 laser could decrease enamel acid solubility.

Design and Fabrication of a Novel Transplant Combined with Human Bone Marrow Mesenchymal Stem Cells and Platelet-rich Fibrin: New Horizons for Periodontal Tissue Regeneration after Dental Trauma

Avulsed teeth that are replanted dried are more prone to loss. Recent tissue engineering studies focus on fabrication of various cell delivery systems to improve the overall prognosis of such teeth. To evaluate this new cell transplant method, we initially aimed at designing of PRF scaffold and determining BMMSCs viability and function on the fabricated scaffold. To test this concept in-vitro, human BMMSCs were isolated and characterized by cell surface marker, and their potential on osteogenic/adipogenic differentiation. The biological effects of PRF scaffold on human BMMSCs were then investigated by cell proliferation assay. The data were quantified for statistical analysis. It was found that PRF significantly induced BMMSCs proliferation throughout the incubation period due to its growth factor secretion. Results of MTT assay showed an increasing trend during the testing period from day 1 to day 7. The result of scanning electron microscopy showed that BMMSCs could tightly adhere to fibrin scaffold just shortly after seeding. These data suggest that the BMMSCs/PRF construct has the potential to improve the clinical prognosis of replanted avulsed teeth in future. Additional studies are needed to be performed before its clinical use.

A case-report of delayed repositioning of intruded permanent maxillary central incisors accompanied by complicated crown fractures: A 2-year follow-up

Intrusive luxation is the most severe type of dental injury with a complex healing sequence. Pulp necrosis, root resorption (surface, inflammatory and replacement resorption), and defects in marginal periodontal bone healing are the main complications. Treatment strategies can be either active, by repositioning (surgical or orthodontic extrusion), or passive, by spontaneous re-eruption based on the thorough evaluation of the case. This paper reports a case of delayed repositioning of severely intruded permanent maxillary central incisors accompanied by complicated crown fractures after 3 months. After thorough clinical and radiographic evaluations, and based on guidelines, the teeth were surgically repositioned and splinted for 6 weeks. One week after the initial intervention, the endodontic treatment for both permanent maxillary incisors were initiated using calcium hydroxide. 6 months later, the teeth were ready for MTA plug and gutta-percha root canal filling. During the follow-up period, the teeth had remained functional and esthetically acceptable. Further yearly observations are planned at least for 5 years.

Bilateral Supernumerary Deciduous Maxillary Lateral Incisors with Fusion: Report of a Rare Case

Dental anomaly in number, size and shape might be due to excessive activation of dental lamina during the morpho-differentiation stage. Fusion is one of the most unusual and rare anomalies of shape of the teeth. It frequently involves the supernumerary teeth resulting in a challenging differential diagnosis with gemination. Dental anomalies may result in different problems such as delayed eruption and crowding; thus, early diagnosis is required for effective intervention and proper in-time treatment. The case reported here is a 4-year-old girl with bilateral supernumerary primary maxillary lateral incisors associated with fusion between primary maxillary left lateral incisor and supernumerary lateral tooth.

Cloning, Expression and Characterization of Zebra Fish Ferroportin in Hek 293T Cell Line

BACKGROUND

Ferroportin (Fpn), a regulator of iron homeostasis is a conserved membrane protein that exports iron across the enterocytes, macrophages and hepatocytes into the blood circulation. Fpn has also critical influence on survival of microorganisms whose growth is dependent upon iron, thus preparation of Fpn is needed to study the role of iron in immunity and pathogenesis of micoorganisms.

METHODS

To prepare and characterize a recombinant ferroportin, total RNA was extracted from Indian zebrafish duodenum, and used to synthesize cDNA by RT-PCR. PCR product was first cloned in Topo TA vector and then subcloned into the GFP expression vector pEGFP-N1. The final resulted plasmid (pEGFP-ZFpn) was used for expression of Fpn-EGFP protein in Hek 293T cells.

RESULTS

The expression was confirmed by appearance of fluorescence in Hek 293 T cells. Recombinant Fpn was further characterized by submission of its predicted amino acid sequences to the TMHMM V2.0 prediction server (hidden Markov model), NetOGlyc 3.1 and NetNGlyc 3.1 servers. The obtained Fpn from indian zebrafish also contained eight transmembrane domains with N- and C-termini inside the cytoplasm and harboured 78 O-glycosylated amino acids.

CONCLUSION

The recombinant Fpn from Indian zebra fish was successfully expressed in Hek 293 cell line. Although the discrepancy in two amino acids was observed in our produced Fpn and resulted in an additional O-glycosylation site, but had no effect on the topology of the protein compared to other Fpn described by other researchers. Therefore this construct can be used in future iron studies.

Etiology of pediatric chronic kidney diseases in north-west of Iran

The aim of this study was to evaluate the etiology of pediatric Chronic Kidney Disease (CKD) in a tertiary care hospital in north-west of Iran. Medical records of admitted children with CKD in Children's Hospital of Tabriz from 1999 to 2009 were studied retrospectively. CKD was defined as GFR less than 60 mL min(-1) 1.73 m2 for more than 3 month. The etiology of CKD was determined by clinical, biological, radiological and histopathological examination. During 10 years 115 children including 61 boys (53%) and 54 girls (47%) were studied. The mean age of patients was 8.1 +/- 3.53 years (range: 4 months to 14 years). Urological abnormalities were the most common cause of CKD (36.5%) followed by acquired glomerular diseases (23.5%), hereditary nephropathies (21.7%), unknown etiology (9.5%) and systemic diseases (6%). The most common urologic anomaly was vesicoureteral reflux (VUR) that accounted for 24.3% of total etiologies followed by obstructive uropathies. Focal segmental glomerulosclerosis was the most frequent glomerular disease and was responsible for 13.9% of patients. Nephronophtisis, cystinosis, infantile polycystic disease and congenital nephrotic syndrome were the most frequent hereditary nephropathies in a descending order. Frequency of parental consanguinity in patients with hereditary nephropathy was significantly higher than other patients (p = 0.001). High frequency of VUR in present study compared with developed countries necessitates more efforts for improving the management and follow up of urinary tract infections.