Artificial Caries Lesions Research Articles

Effects of Different Bleaching Agents on the Surface Topography and the Microhardness of Artificial Carious Lesions.

Objectives The aim of this study was to evaluate the effects of in-office and at-home bleaching agent applications on the surface topography and microhardness of artificially demineralized enamel. Materials and Methods A total of 224 enamel specimens were prepared using bovine sound central incisors. 4 mm × 4 mm enamel windows were exposed on the buccal surfaces covering the remaining surface with nail varnish. Samples were immersed in a demineralizing solution for 16 hours to produce artificial caries lesions, then divided into four groups according to the bleaching agent’s type and concentration. Group I; in-office bleaching 35% hydrogen peroxide (HP) (Whiteness HP Maxx; FGM, Brazil), Group II and Group III at-home bleaching 16 and 22% carbamide peroxide CP, respectively (Whiteness Perfect). Group IV; control (not bleached). The microhardness Vickers hardness number (VHN) was measured at the baseline, after demineralization, and after bleaching consequently. The micro-surface changes of the enamel surface after demineralization and bleaching were evaluated by scanning electron microscope (SEM). Statistical Analysis Data were evaluated by the one-way analysis of variance (ANOVA) test followed by Post Hoc Tukey’s and Fisher’s least significant difference. Tow- sided p -values were considered statistically significant at p ≤ 0.05. Results A significant reduction was noticed in the enamel microhardness after demineralization p < 0.05. However, there is no statistically significant difference between the mean VHN of the demineralized and bleached enamel ( p > 0.001). SEM images showed significant changes on the surface of the demineralized enamel after bleaching (pattern type III). Conclusions The low and high concentrations of HP and CP bleaching agents increased the demineralization severity of artificial caries lesions without significantly altering their microhardness values.

Comparative Evaluation of Two Remineralizing Agents on Artificial Carious Lesion Using DIAGNOdent.

PurposeThe current in vitro study was conducted to assess the remineralization potential of CPP-ACP and a customized dentifrice (tricalcium-phosphate) on artificial carious lesions using DIAGNOdent.Materials and methodsFifty-one extracted premolars that satisfied the inclusion criteria were painted using acid-resistant nail varnish. A window of 4 × 4 mm was exposed on the center of the buccal surface of each tooth. After 20 minutes of drying, the baseline reading of enamel specimens was assessed using DIAGNOdent. The teeth were then immersed in a bath of demineralizing solution. An incubation period of 96 hours at 37°C resulted in artificial caries-like lesions on the specimen. Readings of the specimen within the window after demineralization were recorded using DIAGNOdent for all the samples. The specimens were divided into three groups randomly [group I—casein phosphopeptide-amorphous calcium phosphate (CPP-ACP), group II—customized dentifrice, group III—artificial saliva]. Samples were subjected to the daily treatment regimen for a period of 30 days. The samples were evaluated for remineralization by laser fluorescent device (DIAGNOdent) on the 15th and 30th day, respectively.ResultsThe statistical analysis was done using the Friedman test, Kruskal–Wallis test, Wilcoxon sign rank test, and Mann–Whitney test. The results showed that both CPP-ACP and customized dentifrice showed almost similar remineralization potential but CPP-ACP showed significant remineralization (p < 0.001).ConclusionThe DIAGNOdent observation conclusively proves that CPP-ACP and customized dentifrice remineralizes the demineralized tooth samples in vitro with CPP-ACP showing significant remineralization.How to cite this articleArjun DS, Bhat SS, Hegde SK, et al. Comparative Evaluation of Two Remineralizing Agents on Artificial Carious Lesion Using DIAGNOdent. Int J Clin Pediatr Dent 2021;14(2):192–195.

Remineralising dentine caries using an artificial antimicrobial peptide: An in vitro study

ObjectiveTo investigate the antibacterial and remineralising effects of a novel dual-action antimicrobial peptide, GA-KR12, on artificial dentine caries. MethodsHuman dentine blocks with artificial carious lesions were allocated to two groups – Group 1: dentine blocks treated with the novel antimicrobial peptide GA-KR12 twice daily; Group 2: dentine blocks received water as the negative control. Two groups underwent Streptococcus mutan biofilm–remineralisation cycles at 37 °C for 7 days. The morphology, viability and growth kinetics of the S. mutans biofilm were evaluated by scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM) and colony-forming unit (CFU) counting, respectively. The dentine blocks’ lesion depths and mineral loss, changes in chemical structure, dentine surface morphology and crystal characteristics were determined using micro-computed tomography, Fourier transform infrared (FTIR), SEM and X-ray diffraction (XRD), respectively. ResultsThe surface of the dentine blocks in Group 1 was partially covered by S. mutans with damaged cell structure. Group 2 showed affluent growth of S. mutans covering the dentine surface when compared to Group 1. The dead-to-live ratio of Group 1 and Group 2 were 0.78 ± 0.01 and 0.47 ± 0.08, respectively (p < 0.001). The Log CFUs of Group 1 and Group 2 were 7.14 ± 0.30 and 8.24 ± 0.20, respectively (p < 0.001). The lesion depths of Group 1 and Group 2 were 109 ± 1 µm and 135 ± 3 µm, respectively (p < 0.001). The mineral loss of Group 1 and Group 2 were 0.59 ± 0.08 gHApcm−3 and 0.81 ± 0.07 gHApcm−3, respectively (p < 0.001). FTIR showed the amide I-to-hydrogen phosphate (HPO42−) ratios of Group 1 and Group 2 were 0.25 ± 0.05 and 0.39 ± 0.05 (p < 0.001), respectively. SEM images showed Group 1 had less exposed dentine collagen fibres than Group 2. The XRD revealed that the hydroxyapatite in Group 1 was well crystalised. ConclusionThis study demonstrated that the novel antimicrobial peptide GA-KR12 inhibited the growth of S. mutans biofilm and enhanced the remineralisation of artificial dentine caries.

Evaluation of two remineralizing agents used for treatment of artificial caries lesions:

Evaluation of two remineralizing agents used for treatment of artificial caries lesions:

Resistance against Erosive Challenge of Dental Enamel Treated with 1,450-PPM Fluoride Toothpastes Containing Different Biomimetic Compounds.

Objectives This in vitro study aimed to characterize the superficial and subsurface morphology of dental enamel treated with fluoridated gels containing different biomimetic compounds after erosive challenge. Materials and Methods Bovine incisor teeth were sectioned to obtain enamel blocks (4 mm × 4 mm × 6 mm; n = 5) that were demineralized to create an artificial caries lesion and treated by pH cycling interspersed with exposure to fluoridated toothpaste slurries under agitation. During pH cycling (demineralization and remineralization for 2 and 22 hours, respectively) for 6 days, the enamel blocks were exposed to toothpaste slurries under agitation with one of the dental gels: Regenerate Enamel Science (NR-5 technology), Daily Regenerator Dental Clean (REFIX technology), and Sensodyne Repair & Protect (Novamin technology). The enamel blocks were subjected to an erosive challenge, immersed in 50% citric acid for 2 minutes, and then washed with plenty of distilled water. The surface and cross-sectional micromorphology were assessed using scanning electron microscope (SEM). The elemental analyses (weight percentage) were determined with an energy-dispersive X-ray spectroscopy (EDS). Results Enamel treated with the product containing REFIX technology presented a smoother surface morphology compared to the other treatments. The higher resistance to the erosive challenge can be attributed to a silicon-enriched mineral layer formed on the enamel induced by the REFIX-based toothpaste. This was not observed in the specimens treated with the other technology-containing toothpastes. Conclusion The REFIX technology seemed to be the most promising compared to the Novamin and NR-5 technologies. In addition to forming a surface mineralized layer, the enamel treated with REFIX technology associated with the pH cycling resisted a subsequent erosive challenge.

Comparative evaluation of the spectral-domain optical coherence tomography and microhardness for remineralization of enamel caries lesions

This study aimed to evaluate the Cirrus high-definition (HD) spectral-domain optical coherence tomography (SD-OCT) for the remineralization of artificial enamel caries and to compare it with the comparison surface microhardness (SMH) analysis. Artificial caries lesions were produced on forty human enamel samples. Then, three different remineralization agents containing casein phosphopeptide amorphous calcium phosphate; casein phosphopeptide amorphous calcium fluoride phosphate; calcium glycerophosphate, magnesium chloride, and xylitol; and remineralization solution (control) were applied with pH cycling for six days. The optical depth of backscattered light and microhardness of enamel were measured using SD-OCT and SMH. All remineralization agents were significantly efficient in reducing optical lesion depth on enamels (p1=0.001, p2=0.002, p3=0.006, p4=0.025), and in increasing the SMH of enamels (p1-3=0.005, p4=0.017). However, the optical lesion depths of the enamel showed no correlation with the SMH in the groups. In conclusion, demineralization and remineralization of artificial lesions can be assessed with both SD-OCT and SMH.

Remineralization Potential of Nanohydroxyapatite Toothpaste Compared with Tricalcium Phosphate and Fluoride Toothpaste on Artificial Carious Lesions.

Introduction Nanohydroxyapatite (nano-HA) has been utilized as an alternative agent for dental enamel remineralization. This study compared remineralization potential of nano-HA toothpaste (NHT), functionalized tricalcium phosphate toothpaste (TCPT), and fluoride toothpaste (FT) on carious lesions. Materials and Methods Sixty extracted human premolars were prepared for artificial carious lesions with synthetic polymer gel. Samples were divided into four groups according to testing agents: NHT, TCPT, FT, and one group with no treatment (NT). Each group was subjected to pH-cycling with the application of toothpaste in slurry form twice a day (2-min each) for 10 days. Surface microhardness was measured before demineralization, after demineralization, and after pH-cycling. Hardness at different periods, percentage of hardness recovery (% HR), and percentage of remineralization potential (%RP) were determined and statistically analyzed with ANOVA and Tukey comparisons (α = 0.05). Polarized light microscopy (PLM) was utilized to assess lesion depth. Results Significant remineralization of carious lesions was observed among different toothpastes compared to NT (p < 0.05). No significant difference in remineralization potential was found among NHT, TCPT, and FT (p > 0.05). No significant difference in % HR and % RP was seen among NHT, TCPT, and FT (p > 0.05). PLM indicated a greater decrease in carious depth upon using NHT compared to TCPT and FT, with minimal increase in depth for NT. Conclusions NHT has comparable capability to TCPT and FT in hardness recovery. However, decrease in carious depth was evidenced with PLM for NHT more than TCPT and FT. Thus, NHT was suggested as a potential remineralization product for treating initial carious lesions. Clinical Significance. The study showed that NHT had the potential to remineralize artificial carious lesion. It was confirmed in potential in the lesion depth reduction and forming a new enamel layer. NHT showed its capability as an alternative for dental caries therapeutic.

Comparison of microleakage between different restorative materials to restore marginal gap at crown margin.

BackgroundAn occurrence of secondary caries around the indirect restoration margin is reported to remain a leading cause of failures.ObjectiveThis study aimed to test the interfacial microleakage of conventional glass-ionomer (CGI), resin-modified glass ionomer (RMGI) and Nano-hybrid composite (CR) restorations at a full veneer margin crown.MethodsNinety human extracted molar teeth were divided into three groups (n = 30). Each group was subdivided into three subgroups (n = 10) according to the extent of the structural defects; The structural defect in G1 had a depth of 1.5 mm, width and length at 2 mm and 1 mm intrusion within the crown cervical margin. The corresponding structural defect dimension values for G2 were 2, 5, 4 and 2 mm with defects extending onto the root structure. Meanwhile, G3: structural deficiency of 2 mm depth, 3 mm width and 3 mm length and with 1.5 mm extension into the prepared teeth. These structural defects in each subgroup were restored with CGI, RMGI and CR. Artificial carious lesion formation was induced at the cervical finish line with a demineralizing solution. The artificial carious lesions were restored as per the group distribution. Subsequently, teeth samples were prepared and cemented with Nickel-chromium full coverage restorations utilizing glass-ionomer luting cement. Teeth samples were thermocycled, isolated with nail varnish, and immersed in 0.1% methylene blue for 24 h. The teeth samples were sectioned longitudinally, dye penetration was evaluated with a stereomicroscope. The data were analyzed with Kruskal–Wallis and Mann–Whitney U tests.ResultsCGI-G1 recorded the highest micro-leakage score at 1.450; while CR-G3 recorded the least score (0.350). At a cementum-restoration interface, CR-G1 (0.850) documented the lowest micro-leakage; RMGI-G3 had a greater value at 1.700.ConclusionsThe hybrid CR could be effectively used to restore the restoration of a marginal gap around crown margins.

Secondary Caries Adjacent to Bulk or Incrementally Filled Composites Placed after Selective Excavation In Vitro.

Objectives: selective caries excavation (SE) is recommended for deep carious lesions. Bulk fill composites (BF) may be considered to restore SE-cavities. We compared the susceptibility for secondary caries adjacent to BF versus incrementally filled composites (IF) in SE and non-selectively excavated teeth (NS) in vitro. Methods: in 72 extracted human premolars, artificial caries lesions were induced on pulpo-axial walls of standardized cavities. The lesions were left (SE) or removed (NS), and teeth were restored using two BF, GrandioSO x-tra/Voco (BF-Gra) and SDR/Dentsply (BF-SDR), and an IF, GrandioSO/Voco (IF-Gra) (n = 12/group for SE and NS). After thermo-mechanical cycling (5–55 °C, 8 days), teeth were submitted to a continuous-culture Lactobacillus rhamnosus biofilm model with cyclic loading for 10 days. Mineral loss (ΔZ) of enamel surface lesions (ESL), dentin surface lesions (DSL), and dentin wall lesions (DWL) was analyzed using transversal microradiography. Results: ΔZ was the highest in DSL, followed by ESL, and it was significantly lower in DWL. There were no significant differences in ΔZ between groups in DSL, ESL, and DWL (p > 0.05). Regardless of lesion location, ΔZ did not differ between SE and NS (p > 0.05). Conclusions: BF and IF both showed low risks for DWL (i.e., true secondary caries) after SE in vitro, and surface lesion risk was also not significantly different between materials. SE did not increase secondary caries risk as compared with NS. Clinical Significance: the risk of secondary caries was low after selective excavation in this study, regardless of whether bulk or incrementally filled composites were used

Remineralizing effect of calcium-sucrose-phosphate with and without fluoride on primary and permanent enamel: Microhardness and quantitative-light-induced-fluorescence™ based in vitro study

To evaluate and compare remineralization potential of commercially available calcium sucrose phosphate (CaSP) (5% EnaFix) individually and with 0.2% Sodium Fluoride (NaF) mouth-rinse (ACT Kids Anticavity Fluoride-Rinse) supplementation through Vickers Microhardness tester (VMH) and Quantitative Light Induced Florescence (QLF™) technology on artificial carious lesions on primary and permanent enamel. In present in-vitro comparative study, artificial carious lesions were created on 60 each, permanent and primary enamel samples followed by pH cycling for a period of 21 days with interventional agents (Control; Distilled water; Test; CaSP alone and CaSP + 0.2% NaF). The samples were evaluated for ΔF values of QLF at, demineralization, 7th, 14th and 21st day and VHN at, demineralization and 21st day of pH cycling. The data were analysed using paired t -test and ANOVA. Intra group comparison showed the statistically significant fluorescence gain with CaSP+0.2%NaF in permanent samples and statistically significant fluorescence gain with both CaSP and CaSP+0.2%NaF in primary samples (p = 0.001). Inter group comparison of interventional agents in both primary and permanent samples showed statistically non-significant variation between CaSP and added NaF group (p = 0.68). Within the limitations of the present study, results showed no significant difference in microhardness improvement and remineralization potential between CaSP and CaSP+0.2%NaF. However, since both showed similar efficacy CaSP looks to be a choice for primary dentition and CaSP with 0.2% NaF can be preferred for mixed dentition with primary and young permanent teeth.

Artificial Caries Lesion Characteristics after Secondary Demineralization with Theobromine-Containing Protocol.

Developing artificial caries lesions with varying characteristics is needed to adequately study caries process in vitro. The objective of this study was to investigate artificial caries lesion characteristics after secondary demineralization protocol containing theobromine and fluoride. Sixty bovine enamel slabs (4 × 3 mm) were demineralized using a Carbopol-containing protocol for 6 days. A baseline area (2 × 3 mm) was protected with acid-resistant nail varnish, after which specimens were exposed for 24 h to a secondary demineralization protocol containing acetic acid plus one of four fluoride/theobromine combinations (n = 15): theobromine (50 or 200 ppm) and fluoride (0 or 1 ppm). Specimens were sectioned and analyzed using transverse microradiography for changes in mineral content, lesion depth, and surface layer mineralization. Data was analyzed using paired t-test and analysis of variance followed by Bonferroni test at 0.05 significance level. After secondary demineralization, fluoride-containing groups had significantly deeper lesions (p = 0.002 and 0.014) compared to the group with 0 ppm fluoride and 50 ppm theobromine. Mineral content and lesion depth were significantly different compared to baseline for all groups. Theobromine did not show an added effect on mineral uptake. Theobromine-containing groups exhibited particularly deep lesions with a more uniform mineral profile in the presence of fluoride.

Silicon-enriched hydroxyapatite formed induced by REFIX-based toothpaste on the enamel surface

Objective: This in vitro study aimed at characterizing the mineral content and filler particle morphology of a fluoridatedtoothpaste containing REFIX technology and the mineral content and the morphology of the enamel surface treatedwith this product. Material and Methods: Bovine enamel blocks (n=5) were obtained (4×4×6 mm), demineralized(artificial caries lesion), and treated (pH cycling and brushing with the toothpaste). During the pH cycling, which lastedfor 7 days (demineralization and remineralization took 6 h and 18 h, respectively), the enamel was brushed for 5 minusing an electric toothbrush before being immersed in a remineralization solution. We evaluated the micromorphologyand elemental levels (wt%) of ions present in the toothpaste and on the layer formed over the enamel following thetreatment. The surface morphology was assessed using scanning electron microscopy (SEM). The elemental analyseswere performed using an energy-dispersive X-ray spectrometer (EDS). Results: Scanning electron micrographs of thetoothpaste demonstrated a uniform size distribution of regular-shaped fillers sparsely organized in nanoclusters. Elemental analysis of the toothpaste’s formulation demonstrated the presence of Si (silicon), Na (sodium), P (phosphorus), and F (fluorine), among others. We also detected a mineral layer that had formed on the treated enamel surface; the layer had a consistent uniform thickness of ~14 µm. Conclusion: Based on the results, it can be stated that REFIX technology modifies the surface and subsurface of the enamel structure, forming a Si-rich mineral layer. KEYWORDSDental enamel; Dentifrice; Scanning electron microscopy; Tooth remineralization.

Effect of xylitol varnishes on enamel remineralization of immature teeth: in vitro and in situ studies.

We evaluated the efficacy of xylitol varnishes on the remineralization of newly erupted permanent and deciduous teeth in vitro and in situ. Human enamel specimens were randomly allocated to 8 groups (n = 15/group). Artificial caries lesions were produced and enamel alterations were quantified by surface/subsurface hardness and transverse microradiography. The blocks were then treated with the following varnishes: DuraphatTM; 20 wt% xylitol (146 μm) varnish; 20 wt% milled xylitol (80 μm) varnish, and placebo varnish, and removed after 6 h of immersion in artificial saliva. The blocks were subjected to pH-cycles for 8 days. fifteen subjects wore palatal appliances containing four pre-demineralized and treated enamel specimens, for 5 days. Data were statistically analyzed by ANOVA/Tukey and Kruskal-Wallis/Tukey's test (p < 0.05). The %SHR in both studies was significantly increased by xylitol and Duraphat™ varnishes when compared to placebo. Considering subsurface remineralization, only the xylitol varnishes were able to significantly reduce the enamel lesion. Xylitol varnishes can be promising alternatives to promote enamel remineralization of newly erupted permanent and deciduous teeth.

Tara Gum as a Controlled Delivery System of Fluoride in Toothpaste: In Vitro Enamel Remineralization Study

Objective: To evaluate the remineralizing potential of a hydrocolloid-based, controlled fluoride-releasing system added to dentifrice formulas. Material and Methods: Sixty-five human enamel blocks were prepared and the surface microhardness (SH0) values were determined. The artificial caries lesions were induced and the demineralization surface microhardness (SH1) was evaluated. The blocks were randomly allocated into five groups (n = 13): (1) 100-TGF (100% NaF with Tara gum added); (2) 50-TGF (50% free NaF + 50% NaF with Tara gum added); (3) 100% TG (100% Tara gum without fluoride); (4) 100% NaF (positive control); and (5) placebo (without Tara gum and NaF). The blocks were submitted to 7 days pH cycling and treated with dentifrice slurries twice a day. Finally, surface hardness (SH2) was assessed and the percentage of surface hardness recovery (%SMHR) was calculated. Analysis of variance (ANOVA) followed by Bonferroni test was used for statistical analysis. Results: A positive %SMHR was found in the 100% NaF (5.07) and 50-TGF (0.64) groups, while the 100-TGF (-1.38), 100% TG (-3.88) and placebo (-0.52) did not undergo remineralization. Statistically significant differences were observed between 100% NaF and all the groups except for 50-TGF (p<0.05). Conclusion: The presence of hydrocolloid (Tara gum) promoted minimal remineralization when associated with NaF. In the applied model, Tara gum may have compromised remineralization, preventing free fluoride from acting effectively in the carious lesion.

Enamel remineralization and surface roughness after treatment with herbal-containing toothpastes.

BackgroundOral care products containing bioactive agents obtained from extracts of plant drugs were launched. This in vitro study investigated the effects of herbal-containing toothpastes associated or not with fluoride to remineralize the enamel after cariogenic challenge with pH cycling. The chemical and physical factors of toothpastes and the enamel surface roughness after brushing were also analyzed. Material and MethodsSixty bovine enamel blocks were obtained and divided into 3 thirds: intact (untreated), demineralized (artificial caries lesion), and treated (caries lesion, pH cycling, and brushing with toothpastes). Toothpastes containing herbal compounds contained no fluoride [Galla chinensis (GCH)], low-F concentration [D’Or (DOR); Herbal Bliss (HBL)], or a different fluoride type [Elmex Anticaries (EAC)]. The results were compared to NaF-containing toothpastes: 1450 and 5000 ppm. Enamel blocks were brushed with the toothpastes using a pH-cycling model (7 days). The Knoop hardness (25g/10s) of the surface and the longitudinal sections were then evaluated. The percentage of surface hardness recovery (%SHR) was calculated. The enamel surface roughness, pH, particle size, zeta potential, and polydispersity index of toothpaste slurries were also evaluated. Data were statistically analyzed (α=5%). ResultsNo significance was observed when %SHR was compared (p>0.05). DOR, GCH, and HBL were more effective in remineralizing the enamel subsurface. Significantly higher surface roughness was observed when treated with EAC and GCH (p<0.05). ConclusionsAll toothpastes were able to remineralize the enamel, especially the subsurface, with results equal or better than that of standard toothpastes. Key words:Enamel, hardness, roughness, toothpaste, tooth remineralization.

Development of strontium-doped nano hydroxyapatite dentifrice and compare its remineralising potential with a topical cream containing casein phosphopeptide- amorphous calcium phosphate - An In Vitro study.

To develop and evaluate the efficacy of synthesised strontium-doped nano hydroxyapatite dentifrice and compare its remineralizing potential with a topical cream containing Casein Phospho Peptide - Amorphous Calcium Phosphate, in remineralizing artificial carious lesion on enamel. Enamel specimens of 4 x 4 x 1 mm were prepared from 90 freshly extracted teeth. Specimens were divided into 3 groups of 30 samples each, based on the type of dentifrice applied that is a control group (Group I) and two experimental groups (Groups II, III). Surface topography and the calcium/phosphorous ratio of all sound specimen were evaluated using Scanning electron microscope and Energy Dispersive X-ray Analysis (SEM-EDAX). The samples in group I and each of the experimental groups were subjected to demineralisation and the calcium/phosphorous ratio of the demineralized specimen were analysed. The samples were then subjected to remineralisation using different agents in each group. Samples in the control group (Group I) were brushed with a conventional dentifrice. In the experimental groups, Group II topical cream with Casein Phosphopeptide and Amorphous Calcium phosphate (CPP-ACP) was used and in Group III laboratory synthesized Strontium-doped nanohydroxyapatite paste (Sr-nHAP), respectively for 28 consecutive days. The samples in the both the control and the two experimental groups were again subjected to SEM-EDAX analysis to analyse the calcium phosphorus ratio following remineralisation cycle. Groupwise comparison of the data was done with one way ANOVA followed by Tukeys Post hoc Test. Both experimental groups (II, III) showed statistically significant remineralisation potential after demineralisation, compared to the control group I. Intergroup comparison showed that the samples in Group III showed the higher remineralisation potential than Group II and was statistically significant. Both CPP- ACP containing tooth cream as well as Sr doped nHAp showed remineralisation potential. Sr doped nanohydroxyapatite showed better remineralisation than CPP ACP and can be considered for enamel repair in incipient carious lesions.

Antimicrobial activity of a remineralizing paste containing Strontium doped Nano hydroxyapatite (Sr-nHAp) with Non Collagenous Protein (NCP) analogue Chitosan – An in vitro study

Dental caries is an infectious multifactorial disease. Biomimetic remineralisation of non-infected carious dentine helps in retaining tissues to a maximum degree during vital pulp treatment. However micro gaps and residual bacteria below restorations lead to microleakage, degradation of tooth structure and secondary caries. Remineralizing agent with anti-bacterial efficacy would help contain secondary caries and its sequelae. The aim of the study was to evaluate the antimicrobial activity of remineralizing paste containing Strontium doped Nano hydroxyapatite (Sr-nHAp) with Non Collagenous Protein (NCP) analogue, Chitosan. In this study dentin slabs, 200 µm thick obtained from freshly extracted premolars were demineralised and inoculated with Streptococcus mutans to simulate artificial carious lesion. The specimens were divided in to six groups based on the reminerlising regimen, Group 1–10 wt%Sr-nHAp, Group 2–20 wt%Sr-nHAp, Group 3–10 wt%Sr-nHAp + Chitosan and Group 4–20 wt%Sr-nHAp + Chitosan, Group 5 Positive control – Calcium hydroxide and Group 6, negative control, no treatment. The dentin specimens were homogenised and assessment of bactericidal effects was done by counting the number of viable bacteria after 48 h of incubation. Agar well diffusion test was performed to measure the zone of inhibition. Results were tabulated and analysed statistically using, ANOVA and Post – hoc Bonferroni tests (P = 0.05). All experimental groups except Group 1, exhibited antibacterial properties observed by Zone of Inhibition and reduced colony forming units. Antibacterial efficacy of the remineralizing paste was enhanced by the addition of Chitosan and its antimicrobial efficacy was comparable to calcium hydroxide.

REMINERALIZATION OF PRIMARY MOLAR DENTINE WITH SILVER DIAMINE FLUORIDE AND SODIUM FLUORIDE : AN IN VITRO STUDY

ABSTRACT Objectives: Silver diamine fluoride (SDF) offers a minimally invasive and inexpensive alternative to traditional restorative caries treatment. Aim of this study was to evaluate the mineral density value and remineralization effect of 38% SDF solution and 5% sodium fluoride (NaF) varnish on artificial primary tooth dentin caries lesions. Materials and Methods: 54 extracted sound primary molars were demineralized and allocated into two groups: SDF and NaF groups. After pH-cycling, mineral density values (MDV) were assessed with micro computed tomography (micro-CT) and surface morphology were studied via scanning electron microscopy (SEM). Results: After remineralization agents were apllied and specimens pH-cycled, the MDVs of the Region of Interest (ROI) in lesions increased in both NaF and SDF group. The mean MDV of SDF applied specimens was found to be higher than NaF applied specimens at statistically significant level. In the SEM images, it was observed that the dentinal tubules orifices were occluded almost completely in SDF group while the orifices in NaF group were partially occluded. Conclusions: The use of 38% SDF demonstrated a great remineralization effect on primary molar dentin than 5% NaF varnish. Further clinical studies are needed to investigate the effect of 38% SDF on primary molars which remains in the mouth longer than incisors and have a great function on chewing.

Demineralization Inhibitory Effects of Highly Concentrated Fluoride Dentifrice and Fluoride Gels/Solutions on Sound Dentin and Artificial Dentin Caries Lesions in vitro

Objectives: The aim of this in vitro study was to compare the demineralization inhibitory effect of gels/solutions used in combination with either standard or highly fluoridated dentifrices on sound dentin as well as on artificial dentin caries-like lesions. Methods: Bovine dentin specimens (n = 240) with two different surfaces each (sound [ST] and artificial caries lesion [DT]) were prepared and randomly allocated to twelve groups. Weekly interventions during pH-cycling (28 days, 6 × 120 min demineralization/day) were: the application of gels/solutions containing amine fluoride/sodium fluoride (12,500 ppm F [ppm]; pH = 4.4; AmF); NaF (12,500 ppm; pH = 6.6; NaF1); NaF (12,500 ppm; pH = 6.3; NaF2); silver diamine fluoride (14,200 ppm; pH = 8.7; SDF); acidulated phosphate fluoride (12,500 ppm; pH = 3.8; APF), and no intervention (standard control; S). Furthermore, half of the specimens in each group were brushed (10 s; twice per day) with dentifrice slurries containing either 1,450 ppm (e.g., AmF₁₄₅₀) or 5,000 ppm (e.g., AmF₅₀₀₀). Differences in integrated mineral loss (ΔΔZ) and lesion depth (ΔLD) were calculated between values before and after pH-cycling using transversal microradiography. Results: After pH-cycling Ss showed significantly increased ΔZ_DT and LD_DT values, indicating further demineralization. In contrast, except for one, all groups including fluoride gels/solutions showed significantly decreased ΔZ_DT values. Additional use of most fluoride gels/solutions significantly enhanced mineral gain, mainly in the surface area; however, acidic gels/solutions seemed to have negative effects on lesion depths. Significance: Under the present pH-cycling conditions the highly fluoridated dentifrice significantly reduced caries progression and additional application of nearly all of the fluoride gels/solutions resulted in remineralization. However, there was no difference in the remineralizing capacity of fluoride gels/solutions when used in combination with either standard or highly fluoridated dentifrices.

The Effect of Topical Application of Strontium on Bond Strength in Orthodontics. (In Vitro Study)

Objective: to evaluate the effects of topical application of strontium on bond strength in orthodontics in vitro by using Instron universal testing machine . Materials and Methods: forty eight bovine enamel specimens were randomly allocated to four groups (n =12). Specimens of group I were not demineralized and were not pretreated, but served as controls. The other specimens were demineralized by using Featherstone pH cycling technique to form artificial carious lesions. Samples from group II were only demineralized. The other samples were pretreated with strontium chloride solution(Srcl2) for 5 minutes. Teeth in groups III were treated with Srcl2 solution before acid-etching. Teeth in groups IV were treated with Srcl2 after acid-etching. The brackets were then bonded .The brackets' SBS was measured and the adhesive remnant was assessed using adhesive remnant index (ARI). Analyses were done for SBS values between the four groups using One-Way ANOVA test followed by Post Hoc Tukey’s analysis between each two groups .Fisher’s exact test was used to evaluate differences in ARI scores between the groups. Results: srcl2treated group before acid etching )showed the highest mean SBS value when compared to other groups (Mean ± SD =24.7±7.4 MPa). There was insignificant difference between the four groups as regarding ARI scores (p=0.406). Conclusion: The topical application of srcl2 did not compromise the bond strength of orthodontic brackets to demineralized bovine enamel.