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Dental Materials : Official Publication... Jun 2024Streptococcus mutans (S. mutans) is a major contributor to dental caries, with its ability to synthesize extracellular polysaccharides (EPS) and biofilms. The gcrR gene...
OBJECTIVE
Streptococcus mutans (S. mutans) is a major contributor to dental caries, with its ability to synthesize extracellular polysaccharides (EPS) and biofilms. The gcrR gene is a regulator of EPS synthesis and biofilm formation. The objectives of this study were to investigate a novel strategy of combining gcrR gene over-expression with dimethylaminohexadecyl methacrylate (DMAHDM), and to determine their in vivo efficacy in reducing caries in rats for the first time.
METHODS
Two types of S. mutans were tested: Parent S. mutans; and gcrR gene over-expressed S. mutans (gcrR OE S. mutans). Bacterial minimum inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) were measured with DMAHDM and chlorhexidine (CHX). Biofilm biomass, polysaccharide, lactic acid production, live/dead staining, colony-forming units (CFUs), and metabolic activity (MTT) were evaluated. A Sprague-Dawley rat model was used with parent S. mutans and gcrR OE S. mutans colonization to determine caries-inhibition in vivo.
RESULTS
Drug-susceptibility of gcrR OE S. mutans to DMAHDM or CHX was 2-fold higher than that of parent S. mutans. DMAHDM reduced biofilm CFU by 3-4 logs. Importantly, the combined gcrR OE S. mutans+ DMAHDM dual strategy reduced biofilm CFU by 5 logs. In the rat model, the parent S. mutans group had a higher cariogenicity in dentinal (D) and extensive dentinal (D) regions. The DMAHDM + gcrR OE group reduced the D and D caries to only 20 % and 0 %, those of parent S. mutans + PBS control group (p < 0.05). The total caries severity of gcrR OE + DMAHDM group was decreased to 51 % that of parent S. mutans control (p < 0.05).
SIGNIFICANCE
The strategy of combining S. mutans gcrR over-expression with antibacterial monomer reducing biofilm acids by 97 %, and reduced in vivo total caries in rats by 48 %. The gcrR over-expression + DMAHDM strategy is promising for a wide range of dental applications to inhibit caries and protect tooth structures.
PubMed: 38942710
DOI: 10.1016/j.dental.2024.06.018 -
International Journal of Molecular... Jun 2024Epigenetic modulation, including histone modification, alters gene expression and controls cell fate. Histone deacetylases (HDACs) are identified as important regulators...
Epigenetic modulation, including histone modification, alters gene expression and controls cell fate. Histone deacetylases (HDACs) are identified as important regulators of dental pulp cell (DPC) mineralisation processes. Currently, there is a paucity of information regarding the nature of histone modification and HDAC expression in the dentine-pulp complex during dentinogenesis. The aim of this study was to investigate post-translational histone modulation and HDAC expression during DPC mineralisation and the expression of Class I/II HDACs during tooth development and in adult teeth. HDAC expression (isoforms -1 to -6) was analysed in mineralising primary rat DPCs using qRT-PCR and Western blot with mass spectrometry being used to analyse post-translational histone modifications. Maxillary molar teeth from postnatal and adult rats were analysed using immunohistochemical (IHC) staining for HDACs (1-6). HDAC-1, -2, and -4 protein expression increased until days 7 and 11, but decreased at days 14 and 21, while other HDAC expression increased continuously for 21 days. The Class II mineralisation-associated HDAC-4 was strongly expressed in postnatal sample odontoblasts and DPCs, but weakly in adult teeth, while other Class II HDACs (-5, -6) were relatively strongly expressed in postnatal DPCs and adult odontoblasts. Among Class I HDACs, HDAC-1 showed high expression in postnatal teeth, notably in ameloblasts and odontoblasts. HDAC-2 and -3 had extremely low expression in the rat dentine-pulp complex. Significant increases in acetylation were noted during DPC mineralisation processes, while trimethylation H3K9 and H3K27 marks decreased, and the HDAC-inhibitor suberoylanilide hydroxamic acid (SAHA) enhanced H3K27me3. These results highlight a dynamic alteration in histone acetylation during mineralisation and indicate the relevance of Class II HDAC expression in tooth development and regenerative processes.
Topics: Animals; Acetylation; Rats; Histone Deacetylases; Dentinogenesis; Dentin; Dental Pulp; Protein Processing, Post-Translational; Histones; Molar; Odontoblasts; Male
PubMed: 38928274
DOI: 10.3390/ijms25126569 -
Dental Materials Journal Jun 2024This study aimed to compare the effect of silver diamine fluoride (SDF) and fluoride varnish (NaF) on the Vickers microhardness (VHN) of enamel and dentin after...
This study aimed to compare the effect of silver diamine fluoride (SDF) and fluoride varnish (NaF) on the Vickers microhardness (VHN) of enamel and dentin after radiotherapy and pH-cycling. Human premolars were cut longitudinally, embedded and serially polished. The VHN of enamel/dentin and irradiated enamel/dentin were evaluated. The irradiated specimens were treated with either NaF or SDF, subjected to pH-cycling then VHN test for 4 days. Consequently, they were subjected to energy-dispersive X-ray (EDX) analysis. Radiation adversely affect enamel VHN (p<0.05), whereas dentin VHN was not affected (p>0.05). After pH-cycling, a significant decrease in dentin VHN was observed on day 2 for all groups, whereas enamel VHN was significantly decreased in the control group on day 4. SDF-treated enamel demonstrated higher VHN than that of NaF on day 3. Caries prevention effect of SDF and NaF were observed on enamel, where SDF was proved to be superior to NaF.
PubMed: 38925978
DOI: 10.4012/dmj.2024-032 -
American Journal of Biological... Jun 2024Nitrogen isotopes (δN) are widely used to study human nursing and weaning ages. Conventional methods involve sampling 1-mm thick sections of tooth dentine-producing an...
OBJECTIVES
Nitrogen isotopes (δN) are widely used to study human nursing and weaning ages. Conventional methods involve sampling 1-mm thick sections of tooth dentine-producing an averaging effect that integrates months of formation. We introduce a novel protocol for measuring δN by multicollector secondary ion mass spectrometry (SIMS).
MATERIALS AND METHODS
We sampled dentine δN on a weekly to monthly basis along the developmental axis in two first molars of healthy children from Australia and New Zealand (n = 217 measurements). Nitrogen isotope ratios were determined from measurements of CN secondary molecular ions in ~35 μm spots. By relating spot position to enamel formation, we identified prenatal dentine, as well as sampling ages over more than 3 years. We also created calcium-normalized barium and strontium maps with laser ablation-inductively coupled plasma-mass spectrometry.
RESULTS
We found rapid postnatal δN increases of ~2‰-3‰, during which time the children were exclusively breastfed, followed by declines as the breastfeeding frequency decreased. After weaning, δN values remained stable for several months, coinciding with diets that did not include meat or cow's milk; values then varied by ~2‰ starting in the third year of life. Barium did not show an immediate postnatal increase, rising after a few months until ~1-1.5 years of age, and falling until or shortly after the cessation of suckling. Initial strontium trends varied but both individuals peaked months after weaning.
DISCUSSION
Developmentally informed SIMS measurements of δN minimize time averaging and can be precisely related to an individual's early dietary history.
PubMed: 38923412
DOI: 10.1002/ajpa.24991 -
Journal of Applied Oral Science :... 2024To evaluate the protective effect of an experimental solution containing TiF4/NaF on the development of radiation-induced dentin caries lesions.
OBJECTIVE
To evaluate the protective effect of an experimental solution containing TiF4/NaF on the development of radiation-induced dentin caries lesions.
METHODOLOGY
bovine root samples were irradiated (70Gy) and distributed as following (n=12/group): Commercial Saliva (BioXtra), NaF (500 ppm F-), TiF4 (500 ppm F), TiF4/NaF (TiF4: 300 ppm F-, NaF: 190 ppm F-), and Phosphate buffer solution (PBS, negative control). Biofilm was produced using biofilm from irradiated patients and McBain saliva (0.2% of sucrose, at 37oC and 5% CO2) for five days. The treatments were applied 1x/day. Colony-forming units (CFU) were counted and demineralization was quantified by transversal microradiography. The ANOVA/Tukey test was applied for all parameters.
RESULTS
All treatments reduced CFU for total microorganisms. TiF4 reduced Lactobacillus sp. (7.04±0.26 log10 CFU/mL) and mutans streptococci (7.18±0.28) CFU the most, when compared to PBS (7.58±0.21 and 7.75±0.17) and followed by NaF (7.12±0.31 and 7.34±0.22) and TiF4/NaF (7.16±0.35 and 7.29± 0.29). TiF4 and Commercial saliva showed the lowest integrated mineral loss (ΔZ-vol%.mm) (1977±150 and 2062±243, respectively) when compared to PBS (4540±335), followed by NaF (2403±235) and TiF4/NaF (2340±200). Commercial saliva was the only to significantly reduce mineral loss (LD-µm) (111±25) compared to PBS (153±24).Mean mineral loss (R-vol%) decreased by 35.2% for TiF4 (18.2±3.3) when compared to PBS (28.1±2.9) Conclusion: TiF4/NaF has a comparable anti-cariogenic effect to TiF4 and Commercial saliva under the model in this study.
Topics: Sodium Fluoride; Cattle; Animals; Dentin; Dental Caries; Biofilms; Fluorides; Saliva; Streptococcus mutans; Time Factors; Analysis of Variance; Microradiography; Cariostatic Agents; Reproducibility of Results; Lactobacillus; Colony Count, Microbial; Tooth Demineralization; Humans; Materials Testing; Reference Values; Treatment Outcome; Statistics, Nonparametric; Titanium
PubMed: 38922242
DOI: 10.1590/1678-7757-2024-0024 -
Brazilian Oral Research 2024This study aimed to evaluate the influence of the Er,Cr:YSGG irradiation and 980-nm diode lasers on the surface roughness (SR) and volume loss (VL) of dentin subjected...
This study aimed to evaluate the influence of the Er,Cr:YSGG irradiation and 980-nm diode lasers on the surface roughness (SR) and volume loss (VL) of dentin subjected to cariogenic challenge. Subsequently, 130 specimens of bovine dentin were divided into the following 13 groups: NT: no treatment; FG: fluoride gel; FV: fluoride varnish; Di: 980-nm diode; Di + FG; Di + FV; FG + D; FV + Di; Er: Er,Cr:YSGG; Er + FG; Er + FV; FG + Er and FV + Er. Er,Cr:YSGG laser parameters were as follows: 0.25 W; 5.0 Hz; 4.46 J/cm2 without water and 55% air. Furthermore, the 980-nm diode laser parameters were 2.0 W; 2.0 Hz; 21.41 J/cm2. The samples from each group were subjected to pH cycling. A confocal laser scanning microscope was used to evaluate SR and VL. Difference between the volume of the reference and treated areas + DES/RE was used to determine SR and VL. The mean values of the different groups were subjected to analysis of variance and Tukey's post-hoc test. The VL values were analyzed using the Kruskal-Wallis and Dunn post-hoc test (p < 0.05). The SR of the reference area did not show a statistically significant 1807-3107-bor-38-e025treatment and cariogenic challenge (p > 0.05). Moreover, VL in the FV + Di and FV + Er groups showed a statistically significant difference compared with areas submitted to different types of treatment and cariogenic challenge (p > 0.05). Er,Cr:YSGG and 980-nm diode lasers associated with fluoride varnishes decreased dentin VL in bovine teeth submitted to cariogenic challenge.
Topics: Cattle; Animals; Lasers, Semiconductor; Dentin; Lasers, Solid-State; Microscopy, Confocal; Surface Properties; Reproducibility of Results; Dental Caries; Analysis of Variance; Reference Values; Fluorides, Topical; Cariostatic Agents; Time Factors; Hydrogen-Ion Concentration
PubMed: 38922205
DOI: 10.1590/1807-3107bor-2024.vol38.0045 -
Frontiers in Dentistry 2024This study assessed the effect of chlorhexidine (CHX) and isopropyl alcohol (IA) on immediate and late pushout bond strength (PBS) of fiber posts to dentin. In this in...
This study assessed the effect of chlorhexidine (CHX) and isopropyl alcohol (IA) on immediate and late pushout bond strength (PBS) of fiber posts to dentin. In this in vitro study, 54 single-canal premolars were endodontically treated, and randomly assigned to 3 groups (N=18) for root dentin conditioning with distilled water (control), 2% CHX, and 70% IA after post space preparation. Fiber posts were cemented with TheraCem self-adhesive cement, and each group was subdivided into two subgroups (N=9) for PBS measurement immediately after bonding, and after 5000 thermal cycles (5-55°C). The roots were then sectioned, and their PBS was measured. The mode of failure was evaluated under a stereomicroscope at ×40 magnification. Data were analyzed by repeated measures ANOVA and Tukey's test (alpha=0.05). The highest PBS was noted in the IA group (21.12 MPa) after 24 hours and the lowest PBS belonged to the control group after thermocycling (7.48 MPa). The immediate and post-thermocycling PBS were significantly lower in the control group than the CHX group (P<0.05). The PBS in both the control and CHX groups was lower than that in the IA group (P<0.001). Regardless of the type of detergent, a significant reduction in PBS was observed after thermocycling (P<0.003). The PBS significantly decreased from the cervical towards the apical region in all groups (P<0.001). According to the results, application of IA before the self-adhesive cement effectively improved the immediate and late PBS, and was significantly more effective than CHX
PubMed: 38919768
DOI: 10.18502/fid.v21i13.15374 -
Cureus Jun 2024The purpose of this in vitro study was to evaluate the potential remineralization of enamel and dentine erosion lesions after the application of five different...
OBJECTIVE
The purpose of this in vitro study was to evaluate the potential remineralization of enamel and dentine erosion lesions after the application of five different toothpastes.
METHODOLOGY
A total of 104 enamel and dentine samples were prepared from maxillary third molars. Each group was divided according to the toothpaste application mode (topical = 56; brushing = 48) and the toothpaste used seven topical groups and six brushing groups (n = 8). The groups included negative control (NC), positive control (PC), Sensodyne Pronamel (SP), Regenerate (R), Regenerate with boosting serum (R+), Colgate Duraphat 5000 (CD), and tooth mousse (TM).
RESULTS
The statistical analysis showed significant surface microhardness (SMH) change. All enamel groups showed a significant decrease in SMH compared to NC for both application modes. However, no significance was recorded between test groups. Similar results were observed between dentine groups and their relevant controls for both application modes, except brushed R and R+ groups, which were insignificant to their NC. For topical groups, TM showed a significant increase in SMH. While R and R+ showed lower loss than SP and CD.
CONCLUSIONS
All tested agents offered a degree of remineralization in both enamel and dentine with no significant difference between agents in enamel groups while R, R+, and TM offered better results in dentine groups.
CLINICAL SIGNIFICANCE
For dentine groups, similar findings were observed with superior tooth surface protection with the application of TM over other agents. Tooth surface remineralization was achieved when agents were either applied topically or brushed over the surface.
PubMed: 38912082
DOI: 10.7759/cureus.62921 -
Journal of Dental Research Jun 2024Located at the interface of the dentin-pulp complex, the odontoblasts are specialized cells responsible for dentin synthesis and nociceptive signal detection in response...
Located at the interface of the dentin-pulp complex, the odontoblasts are specialized cells responsible for dentin synthesis and nociceptive signal detection in response to external stimuli. Recent studies have shown that the mechanosensitive ion channel PIEZO1 is involved in bone formation and remodeling through the influx of calcium ions, and it is abundantly expressed in odontoblasts. However, the specific role of PIEZO1 in reactionary dentinogenesis and the underlying mechanisms remain elusive. In this study, we found intense PIEZO1 expression in the plasma membrane and cytoplasm of odontoblasts in healthy human third molars, mouse mandibular molars, and human odontoblast-like cells (hOBLCs). In hOBLCs, PIEZO1 positively regulated DSPP, DMP1, and COL1A1 expression through the Ca/PI3K-Akt/SEMA3A signaling pathway. In addition, exogenous SEMA3A supplementation effectively reversed reduced mineralization capacity in -knockdown hOBLCs. In vivo, Piezo1 expression peaked at day 7 and returned to baseline at day 21 in a wild-type mice dentin injury model, with Sema3a presenting a similar expression pattern. To investigate the specific role of PIEZO1 in odontoblast-mediated reactionary dentinogenesis, mice with a conditional knockout of in odontoblasts were generated, and no significant differences in teeth phenotypes were observed between the control and conditional knockout () mice. Nevertheless, mice exhibited reduced reactionary dentin formation and decreased Sema3a and Dsp positive staining after dentin injury, indicating impaired dental pulp repair by odontoblasts. In summary, these findings suggest that PIEZO1 enhances the mineralization capacity of hOBLCs in vitro via the Ca/PI3K-Akt/SEMA3A signaling pathway and contributes to reactionary dentinogenesis in vivo.
PubMed: 38910430
DOI: 10.1177/00220345241257866 -
Journal of Dentistry Jun 2024to investigate whether baseline mineral distribution modulates the ability of silver diammine fluoride (SDF) to remineralize and stain enamel caries lesions.
OBJECTIVES
to investigate whether baseline mineral distribution modulates the ability of silver diammine fluoride (SDF) to remineralize and stain enamel caries lesions.
METHODS
This laboratory study followed a 3 [treatment: SDF/fluoride varnish (FV)/deionized water (DIW)] ×3 [lesion protocol: methylcellulose (MeC)/hydroxyethylcellulose (HEC)/Carbopol 907 (C907)] factorial design. Lesions were created in bovine enamel specimens (n = 20). Treatments were applied and lesions remineralized in artificial saliva. Digital transverse microradiography (TMR-D) was used to analyze lesions. Lesion color was monitored spectrophotometrically. The effects of lesion protocol and treatment on changes in lesion depth (ΔLD), mineral loss (ΔΔZ), maximum mineral density at the surface zone (ΔSZ), and color changes related to remineralization (ΔL*) were analyzed using two-way ANOVA.
RESULTS
The treatment×lesion protocol interaction was significant for ΔΔZ (p < 0.01) and ΔL* (p < 0.01), however not for ΔLD (p = 0.23) or ΔSZ (p = 0.91). There were no differences in ΔΔZ between treatments in HEC and C907 lesions. However, DIW resulted in more remineralization than both SDF (p < 0.01) and FV (p = 0.01) in MeC lesions. Considering changes from lesion baseline after remineralization in MeC lesions, SDF treatment resulted in the highest mineral gain in the surface zone. However, DIW revealed the highest mineral gain after remineralization in the lesion body. SDF stained lesions with the intensity increasing after remineralization in C907 lesions, whereas staining decreased in MeC and HEC lesions.
CONCLUSION
High fluoride treatments can interfere with continuous remineralization of caries lesions due to partial arrest. Baseline lesion mineral distribution affects SDF's ability to enhance remineralization and the staining caused by SDF.
CLINICAL SIGNIFICANCE
SDF is being used to arrest active caries lesions extending into dentin and to treat dentin hypersensitivity. This study shed light on SDF's effect on an isolated process in dental caries only, remineralization. It achieved this by examining enamel caries lesions with differing mineral distributions and assessing their staining properties.
PubMed: 38897540
DOI: 10.1016/j.jdent.2024.105139