Novel vinegar solution for denture-cleansing agent.

PURPOSE: To study the antimicrobial effects of a novel vinegar-based denture cleansing agent on oral Streptococci and Candida species and the inhibitory effects on pre-formed bacterial and Candida biofilms on denture base. METHODS: The microorganisms used in this study were Streptococcus mutans (S. mutans), Streptococcus sobrinus (S. sobrinus), Streptococcus sanguinis (S. sanguinis), Candida albicans (C. albicans), and Candida glabrata (C. glabrata). The antimicrobial activity of novel vinegar solution was evaluated by time kill assay and biofilm grown on denture base. RESULTS: Time kill assay showed that vinegar exhibited the highest antibacterial effect on S. sobrinus, S. sanguinis, and S. mutans after 15 min of treatment. A 99.9% reduction in C. glabrata and C. albicans required more than 4 and 6 h of treatment, respectively. Vinegar significantly inhibited streptococcal biofilm, with an approximately 6 log-reduction at 30 min of treatment. The results demonstrated that viable Candida cells in biofilm reduced in excess of 6-log CFU/mL after 3 h treatment with vinegar. Moreover, the vinegar-based denture cleanser inhibited bacterial and Candida biofilm formation compared to the control group without treatment with statistical significance. CONCLUSION: A novel vinegar-based denture cleansing agent showed moderate antibacterial properties, but required a slightly longer immersion time to attain anticandidal effects compared to Polident and 0.2% CHX.

Influence of Mouthwash Rinsing on the Mechanical Properties of Polymeric Ligature Ties Used for Dental Applications.

Mouthwashes are used during dental treatments to mitigate the complications caused by poor oral hygiene. However, these solutions also affect the properties of dental appliances, including those used in orthodontics. This point has been investigated in this study focusing on the changes in mechanical properties of polymeric orthodontic ligature ties. Commercial ties from four brands were characterized in terms of their maximum forces and displacement, delivery forces, molecular structures, and microscopic morphology. These properties were compared against the ties, which were rinsed with commercial mouthwashes from three manufacturers. The results showed that mouthwash rinsing significantly reduced the maximum bearable forces of ligature ties by up to 73.1%, whereas the reduction in their maximum displacement was up to 74.5% across all tested brands. Significant changes in microscopic morphology of ligature ties were observed after mouthwash rinsing, but not their molecular structure. Furthermore, mouthwash rinsing also reduced the delivery forces from ligature ties by between 20.9 and 32.9% at their first deformation cycle. It can be concluded from this study that mouthwashes have significant impact on the mechanical properties of polymeric orthodontic ligature ties and could also potentially affect the overall efficacy of orthodontic and other dental treatments.

Buffering capacity and antibacterial properties among bioactive glass-containing orthodontic adhesives.

This study was to evaluate the acid-buffering capacity and antibacterial properties of orthodontic adhesives containing bioactive glasses (BAGs) (45S5, 45S5F, S53P4), Hydroxyapatite, beta-tricalcium phosphate, and Canasite. Fillers comprising 15 wt% bioactive glasses, HAp, ß-TCP, and Canasite incorporated with 55 wt% silanated glass were added to a mixture of UDMA/TEGDMA. Acid-buffering capacity was tested by exposing disc-shaped samples of each adhesive to medium of bacteria-produced acids, and pH changes were recorded at 24 and 48 h. Antibacterial properties were assessed by indirect testing by exposing polymerized adhesive samples to a medium and direct testing by immersing the specimens in solutions containing S. mutans and S. sanguinis. A significant buffering capacity was shown by the 45S5, 45S5F and S53P4 BAG adhesives. The antibacterial properties were not significant in all experimental adhesives. Therefore, the experimental orthodontic adhesives containing BAGs demonstrated a significant buffering capacity but did not show significant antibacterial properties against S. mutans and S. sanguinis.

Effect of surface chemistry-modified polycaprolactone scaffolds on osteogenic differentiation of stem cells from human exfoliated deciduous teeth.

The aim of this study was to investigate the effect of surface modification of a polycaprolactone scaffold on promoting osteogenic differentiation of stem cells from human exfoliated deciduous teeth. Four different polycaprolactone scaffold were evaluated: untreated; coated with hyaluronic acid; coated with gelatin; and coated with hyaluronic acid and then with gelatin. The resulting scaffolds were characterized using scanning electron microscopy and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). Human stem cells were cultured on the modified scaffolds placed in osteogenic differentiation medium. During culture, the osteogenic potential of the stem cells was examined by evaluating alkaline phosphatase activity and staining intensity, expression of osteoblastic-specific genes, and matrix mineralization. Scanning electron microscopy and ATR-FTIR confirmed productive biomacromolecular surface treatment of the polycaprolactone scaffold. All scaffolds permitted differentiation of stem cells into osteoblastic cells, but the gelatin-coated polycaprolactone scaffold facilitated osteogenesis of a larger number of stem cells than the untreated and the hyaluronic acid-coated scaffolds. We demonstrate that gelatin is an appropriate macromolecule for modifying the surface of an electrospun polycaprolactone fibre scaffold that is used subsequently in bone tissue engineering applications.

Optimization of poly (lactic-co-glycolic acid)-bioactive glass composite scaffold for bone tissue engineering using stem cells from human exfoliated deciduous teeth.

OBJECTIVE: The aim of this study was to develop a composite scaffold with the optimal poly(lactic-co-glycolic acid) (PLGA) and bioactive glass proportions to provide an environment for bone tissue regeneration and repair. DESIGN: PLGA-bioactive glass composite scaffolds were prepared using a salt-leaching technique with different percentages of bioactive glass (0%, 10 %, and 15 % [w/w]) with PLGA. The resulting scaffolds were characterized using scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDS), and water contact angle, dynamic mechanical, and pH analysis. The scaffold biocompatibility was investigated using stem cells from human exfoliated deciduous teeth (SHED) and rat experiments. RESULTS: SEM-EDS confirmed the successful fabrication of three-dimensional PLGA-bioactive glass scaffolds. The results showed that 10 % bioactive glass with PLGA exhibited favorable properties including increased pore size, hydrophilicity, and mechanical properties. The growth medium pH was increased for scaffolds containing bioactive glass. All scaffolds were biocompatible, and 10 % bioactive glass composite scaffolding showed better attachment, growth, and proliferation of SHED compared to the other scaffolds. Moreover, it enhanced osteogenic differentiation of SHED in vitro and in vivo. CONCLUSIONS: Salt-leaching-derived PLGA-bioactive glass composite scaffolds were successfully established. PLGA with 10 % bioactive glass had adequate physical properties and bioactivity, and it could be considered as a composite for bone tissue engineering applications.

Impact of household vinegar on calculus removal and mechanical properties of orthodontic resin.

PURPOSE: This study evaluated calculus removal efficacy of household vinegar and its effect on autopolymerizing orthodontic resin following repeated immersion. METHODS: A total of 72 sectioned specimens of orthodontic retainers with calculus deposits following cleaning with the help of immersion in vinegar of different dilutions between 12.5% and 100%, tap water, effervescent tablets, and mechanical debridement were digitally analyzed. Changes in Ca and Fe ions in vinegar were assessed by atomic emission spectroscopy (AES). For mechanical testing, autopolymerizing polymethyl methacrylate (PMMA) samples were similarly grouped and immersed for 78 cycles and their flexural strength and hardness measured. Fourier-transform infrared spectroscopy (FTIR) was performed to evaluate changes in their chemical composition. One-way analysis of variance (ANOVA) and Tukey's test were used to analyze the differences in the mean flexural strength and hardness between the groups (p ≤ 0.05). RESULTS: A minimum immersion of 2 h in 25% vinegar solution combined with brushing attained efficiency of 74.13 ± 22% calculus removal. Whereas, tap water and effervescent tablets had 15% and 49% efficiency, respectively. AES results showed diffusion of Ca ions from calculus into the vinegar solution as a plausible mechanism for its structural weakening and removal. Results of mechanical testing showed that undiluted vinegar solution affected the flexural strength of PMMA and this effect was significantly different from that of the effervescent tablets and the remaining vinegar concentrations. There was no significant difference in hardness between the groups. The FTIR showed no changes in the chemical composition of PMMA samples following repeated immersions. CONCLUSION: Vinegar can be useful in the removal of calculus from dental appliances but should be used in diluted forms to minimize side effects.

Optimal Xeno-free Culture Condition for Clinical Grade Stem Cells from Human Exfoliated Deciduous Teeth.

BACKGROUND AND OBJECTIVES: Stem cells from human exfoliated deciduous teeth (SHED) are a promising clinical resource for various tissue defects, including lumbar spondylosis, neural compression, and cleft palate. Use of media containing animal-derived serum carries potential risk of infectious diseases and unwanted immunogenicity. To increase the potential utility of SHED for clinical application, SHED was adapted to xeno-free conditions. METHODS: Define xeno-free culture media were compared with the conventional serum containing media in the culture of SHED. Cultured SHED in different media were further characterized through proliferative capacities, cellular phenotype, and differentiation potential. RESULTS: Selected xeno-free media were capable of supporting the growth of SHED. MSCGM-CD Bulletkit medium greatly increased the number and proliferate capacity of colony-forming unit-fibroblast than SHED cultured in other media. In addition, the characteristic surface markers expression and multipotent differentiation potential of SHED in the MSCGM-CD Bulletkit medium were comparable to those observed with serum-containing medium. CONCLUSIONS: The xeno-free medium described herein has the potential to be further used for the safe expansion and to determine efficient way to produce clinical grade dental stem cells for therapeutic applications.

Dental arch changes in postretention in Class II division 1 extraction cases.

OBJECTIVE: The purpose of this study is to evaluate the postretention stability of the dental arches in Class II division 1 patients treated with four bicuspid extractions and the edgewise technique. MATERIALS AND METHODS: A digital caliper was used to analyze the dental casts from 29 Class II division 1 malocclusion patients with skeletal type II (14 males, 15 females; ages ranging from 10.2-18.0 years), treated with four bicuspid extractions and the edgewise technique. Intercanine width, intermolar width, arch length, irregularity index, overjet and overbite were evaluated at three times: pretreatment (T1), posttreatment (T2) and postretention (T3) (mean: 4.15 years). Student's t-tests were used to compare the pretreatment-posttreatment, posttreatment-postretention and pretreatment-postretention. Significance was determined at P<0.05. RESULTS: The results of the study are listed as: (1) The upper and lower intercanine widths significantly increased (P<0.05) between T1-T2 and decreased between T2-T3. However, no significant changes were observed between T1-T3; (2) The upper and lower intermolar widths significantly decreased (P<0.05) between T1-T2, between T2-T3 and between T1-T3, except for the upper intermolar width between T2-T3 which showed no significant change; (3) The upper and lower arch lengths significantly decreased (P<0.05) at posttreatment and postretention due to the closure of extraction spaces. Both the upper and lower arch lengths significantly decreased between T1-T2, T2-T3, and T1-T3, except for the upper arch length between T2-T3, which showed no significant change; (4) The irregularity index was significantly improved after treatment. However, there was a slight increase in incisor irregularity at postretention. At postretention, 75.86% of the patients had mild crowding, 20.68% had moderate crowding, 3.48% had severe crowding; (5) The overjet and overbite significantly decreased (P<0.05) between T1-T2 and increased between T2-T3. CONCLUSION: The changes in the dental arches were small at postretention with a tendency to return towards their original position. The overall stability of Class II division 1 extraction cases is relatively good.

Influence of the cross-linking agent on mechanical properties of PMMA powder with compromised particle morphology.

OBJECTIVE: To investigate the effect of a cross-linking agent on the mechanical properties of self-cured orthodontic acrylic resin using PMMA powder (CPM-PMMA) with a compromised microstructure. MATERIALS AND METHODS: The mechanical properties of three sample groups were investigated in this study: CPM-PMMA, orthocryl and orthoplast. CPM-PMMA powder was prepared by suspension polymerization. It was mixed with a commercially available liquid (orthocryl) to yield a test specimen and to compare its flexural properties and Vicker hardness with the two commercial products. Molecular weight and particle size distribution of all groups were examined. Particle morphology was observed using scanning electron microscopy (SEM) and optical microscopy (OM). RESULTS: The average molecular weight of the CPM-PMMA powder was similar to that of the industrial products. Its particle size distribution was narrow and limited to large sizes (91.1-149µm). SEM and OM presented the compromise particle morphology. However, the flexural properties and Vicker hardness of CPM-PMMA powder mixed with orthocryl liquid showed no significant difference compared with orthocryl sample group. In addition, the CPM-PMMA had higher flexural properties than the orthoplast samples. CONCLUSIONS: Although the CPM-PMMA powder presented a compromised particle morphology and narrow particle size distribution, when mixed with orthocryl liquid, the cured resin produced acceptable mechanical properties due to the large amount of cross-linking agent. This result could indicate that the mechanical properties of self-cured acrylic resins are mainly dependent on the amount of cross-linking agent in the liquid component.

Comparison of friction forces between stainless orthodontic steel brackets and TiNi wires in wet and dry conditions.

In sliding mechanics, frictional force is an important counter-balancing element to orthodontic tooth movement, which must be controlled in order to allow application of light continuous forces. The purpose of this study was to compare the frictional forces between a stainless steel bracket and five different wire alloys under dry and wet (artificial saliva) conditions. TiNi, TiNiCu, TiNiCo, commercial wires A and commercial wires B with equal dimensions of 0.016×0.022'' were tested in this experiment. The stainless steel bracket was chosen with a slot dimension of 0.022''. Micro-hardness of the wires was measured by the Vickers micro-hardness test. Surface topography of wires was measured by an optical microscope and quantified using surface roughness testing. Static and kinetic friction forces were measured using a custom-designed apparatus, with a 3-mm stretch of wire alloy at a crosshead speed of 1mm/min. The static and dynamic frictions in the wet condition tended to decrease more slowly than those in the dry condition. Therefore, the friction of TiNiCu and commercial wires B would increase. Moreover, these results were associated with scarred surfaces, i.e. the increase in friction would result in a larger bracket microfracture. From the results, it is seen that copper addition resulted in an increase in friction under both wet and dry conditions. However, the friction in the wet condition was less than that in dry condition due to the lubricating effect of artificial saliva.

Improvement of mechanical and biological properties of TiNi alloys by addition of Cu and Co to orthodontic archwires.

The purpose of this study was to investigate improved performances of TiNi in order to promote tooth movement. Special attention was paid to the effect on the clinical properties of TiNi of adding Cu and Co to this alloy. Ti49.4Ni50.6, Ti49Ni46Cu5 and Ti50Ni47Co3 (at %) alloys were prepared. Specimens were cold-rolled at 30% reduction and heat-treated at 400°C for 60min. Then, the test results were compared with two types of commercial archwires. The findings showed that superelasticity properties were confirmed in the manufactured commercial alloys at mouth temperature. The difference of stress plateau in TiNi, TiNiCo and commercial wires B at 25°C changed significantly at various testing temperatures due to the combination of martensite and austenite phases. At certain temperatures the alloys exhibited zero recovery stress at 2% strain and consequently produced zero activation force for moving teeth. The corrosion test showed that the addition of Cu and Co to TiNi alloys generates an increase in corrosion potential (Ecorr) and corrosion current densities (Icorr). Finally, we observed that addition of Cu and Co improved cell viability. We conclude that addition of an appropriate amount of a third alloying element can help enhance the performances of TiNi orthodontic archwires.

Antimicrobial effects of silver zeolite, silver zirconium phosphate silicate and silver zirconium phosphate against oral microorganisms.

OBJECTIVE: To evaluate the antimicrobial activities of silver inorganic materials, including silver zeolite (AgZ), silver zirconium phosphate silicate (AgZrPSi) and silver zirconium phosphate (AgZrP), against oral microorganisms. In line with this objective, the morphology and structure of each type of silver based powders were also investigated. METHODS: The antimicrobial activities of AgZ, AgZrPSi and AgZrP were tested against Streptococcus mutans, Lactobacillus casei, Candida albicans and Staphylococcus aureus using disk diffusion assay as a screening test. The minimum inhibitory concentration (MIC) and minimum lethal concentration (MLC) were determined using the modified membrane method. Scanning electron microscope and X-ray diffraction were used to investigate the morphology and structure of these silver materials. RESULTS: All forms of silver inorganic materials could inhibit the growth of all test microorganisms. The MIC of AgZ, AgZrPSi and AgZrP was 10.0 g/L whereas MLC ranged between 10.0-60.0 g/L. In terms of morphology and structure, AgZrPSi and AgZrP had smaller sized particles (1.5-3.0 µm) and more uniformly shaped than AgZ. CONCLUSIONS: Silver inorganic materials in the form of AgZ, AgZrPSi and AgZrP had antimicrobial effects against all test oral microorganisms and those activities may be influenced by the crystal structure of carriers. These results suggest that these silver materials may be useful metals applied to oral hygiene products to provide antimicrobial activity against oral infection.

Plaque pH response to snack foods in children with different levels of mutans streptococci.

This study aimed to investigate the effects of some snack foods on plaque pH in children with different levels of mutans streptococci (MS). Six children, aged 9-12 years, with low (<10(4)) and 6 children, aged 10-12 years, with high (>106) numbers of MS/ml saliva participated in the study. Dental plaque pH changes, after the consumption of milk chocolate, sweet biscuit, instant noodle, sticky rice with banana and a 10% sucrose positive control were measured using pH-electrode. The measurements of plaque pH were made on forty-eight-hour accumulated plaque, at baseline to determine the resting pH of the fasted plaque and at time intervals of 2, 5, 10, 20 and 30 minutes after food consumption. The plaque pH curves, delta pH values and area under curve for pH 6.0 for each test food were determined. Plaque acidogenicity was more pronounced for the high-MS group at almost all test periods compared to the low-MS group with all test foods. The test foods were ranked according to maximum pH drop in about the same order in both groups as follows: 10% sucrose > milk chocolate > sweet biscuit > sticky rice with banana > instant noodle. The plaque pH also stayed below pH 6.00 for a longer period in the high-MS group with sweet biscuit, milk chocolate, and sticky rice with banana. Findings suggest that pH responses were more acidic in high-MS group than low-MS group.

Antimicrobial activity of Cratoxylum formosum on Streptococcus mutans.

The gum of Cratoxylum formosum, commonly known as mempat, is a natural agent that has been used extensively for caries prevention by hill tribe people residing in Thailand. The objective of this study was to investigate the antimicrobial activity of Cratoxylum formosum gum on Streptococcus mutans (S. mutans) in vitro. The gum extracted from stem bark of Cratoxylum formosum was investigated for antimicrobial activity against different strains of S. mutans, including S. mutans KPSK2 and 2 clinical isolates. Inhibition of growth was primarily tested by agar diffusion method. A two-fold broth dilution method was then used to determine the minimum inhibitory concentration (MIC) of the extract. The extract of Cratoxylum formosum was effective against S. mutans with the inhibition zones ranging from 9.5 to 11.5 mm and MIC values between 48 microg/ml and 97 microg/ml. The gum of Cratoxylum formosum has high antimicrobial activity against S. mutans and may become a promising herbal varnish against caries.

Relationships between dental calcification stages and skeletal maturity indicators in Thai individuals.

The purpose of this study was to investigate the relationship between the stages of calcification of various teeth and skeletal maturity stages among Thai individuals. The study subjects consisted 139 male subjects and 222 female subjects ranging in age from 7 years to 19 years. A total of 361 hand-wrist and panoramic radiographs were obtained and analyzed. The tooth development of the mandibular canines, first and second premolars, and second and third molars were assessed according to the Demirjian's system. Skeletal age and skeletal maturity stages were determined from hand-wrist radiographs by using the method outlined in the atlas of Greulich and Pyle and the Fishman's system, respectively. The Spearman rank order correlation coefficient revealed significant relationships (r = 0.31-0.69, P < .01) between dental calcification stages and skeletal maturity stages. The second premolar was the tooth showing the highest correlation (r = 0.66 in male subjects, r = 0.69 female subjects). The third molar demonstrated the poorest correlation (r = 0.47 in male subjects, r = 0.31 in female subjects). The canine stage F for both sexes (63.2% for female subjects, 54.1% for male subjects) coincided with the MP3 stage. The second molar stage E for female subjects (51.4%) and stage G for male subjects (66.7%) were related to the S stage and the MP(3cap) stage, respectively. This suggests that tooth calcification stages from panoramic radiographs might be clinically useful as a maturity indicator of the pubertal growth period. However, further study is recommended in a larger sample size, and future studies should address development of the canines and second molars.