Ex vivo study of molecular changes of stained teeth following hydrogen peroxide and peroxymonosulfate treatments.

White teeth can give confidence and tend to be associated with a healthier lifestyle in modern society. Therefore, tooth-bleaching strategies have been developed, including the use of hydrogen peroxide. Recently, peroxymonosulfate has been introduced as an alternative bleaching method to hydrogen peroxide. Although both chemicals are oxidizing agents, their effects on the molecular composition of the stained teeth are yet unknown. In this study, the molecular profiles of teeth bleached with hydrogen peroxide and peroxymonosulfate were compared using Liquid Chromatography-Tandem Mass Spectrometry. Statistical analyses were used to assess the samples. In addition, reference spectral libraries and in silico tools were used to perform metabolite annotation. Overall, principal component analysis showed a strong separation between control and hydrogen peroxide and peroxymonosulfate samples (p < 0.001). The analysis of molecular changes revealed amino acids and dipeptides in stained teeth samples after hydrogen peroxide and peroxymonosulfate treatments. Noteworthy, the two bleaching methods led to distinct molecular profiles. For example, diterpenoids were more prevalent after peroxymonosulfate treatment, while a greater abundance of alkaloids was detected after hydrogen peroxide treatment. Whereas non-bleached samples (controls) showed mainly lipids. Therefore, this study shows how two different tooth-whitening peroxides could affect the molecular profiles of human teeth.

Improved mineralization of dental enamel by electrokinetic delivery of F- and Ca2+ ions.

This in vitro study evaluated the effects of the infiltration of F- and Ca2+ ions into human enamel by electrokinetic flow (EKF) on the enamel microhardness and F- content. Sound human enamel ground sections of unerupted third molars were infiltrated with de-ionized water by EKF and with F- ion by EKF respectively. All samples were submitted to two successive transverse acid-etch biopsies (etching times of 30 s and 20 min) to quantify F- ion infiltrated deep into enamel. Remarkably, sound enamel showed a large increase in microhardness (MH) after infiltration of NaF (p < 0.00001) and CaCl2 (p = 0.013) by EKF. Additionally, NaF-EKF increased the remineralization in the lesion body of artificial enamel caries lesions compared to controls (p < 0.01). With the enamel biopsy technique, at both etching times, more F- ions were found in the EKF-treated group than the control group (p << 0.05), and more fluoride was extracted from deeper biopsies in the NaF-EKF group. In conclusion, our results show that EKF treatment is superior in transporting Ca2+ and F- ions into sound enamel when compared to molecular diffusion, enhancing both the mineralization of sound enamel and the remineralization of artificial enamel caries.

Characterization of white spot lesions formed on human enamel under microcosm biofilm for different experimental periods.

The initial characteristics of white spot lesion (WSLs), such as the degree of integrated mineral loss (ΔZ), depth and pattern of mineral distribution, have an impact on further demineralization and remineralization. However, these lesion parameters have not been evaluated in WSLs produced from microcosm biofilms. OBJECTIVE: This study characterized artificial white spot lesions produced on human enamel under microcosm biofilm for different experimental periods. METHODOLOGY: In total, 100 human enamel specimens (4x4mm) were assigned to 5 distinct groups (n=20/group) differing according to the period of biofilm formation (2, 4, 6, 8 or 10 days). Microcosm biofilm was produced on the specimens from a mixture of human and McBain saliva at the first 8h. Enamel samples were then exposed to McBain saliva containing 0.2% sucrose. WSLs formed were characterized by quantitative light-induced fluorescence (QLF) and transverse microradiography (TMR). Data were analyzed by ANOVA/Tukey or Kruskal-Wallis/Dunn tests (p<0.05). RESULTS: A clear time-response pattern was observed for both analyses, but TMR was able to better discriminate among the lesions. Regarding QLF analysis, median (95%CI; %) changes in fluorescence ∆Z were -7.74(-7.74:-6.45)a, -8.52(-8.75:-8.00)ab, -9.17(-10.00:-8.71)bc, -9.58(-10.53:-8.99)bc and -10.01(-11.44:-9.72)c for 2, 4, 6, 8, and 10 days, respectively. For TMR, median (95%CI; vol%.µm) ∆Z were 1410(1299-1479)a, 2420(2327-2604)ab, 2775(2573-2899)bc, 3305(3192-3406)cd and 4330(3972-4465)d, whereas mean (SD; µm) lesion depth were 53.7(12.3)a, 71.4(12.0)a, 103.8(24.8)b, 130.5(27.2)bc, 167.2(39.3)c for 2, 4, 6, 8 and 10 days, respectively. CONCLUSION: The progression of WSLs formed on human enamel under microcosm biofilm can be characterized over 2-10 days, both by QLF and TMR analyses, although the latter provides better discrimination among the lesions.

Characterization of white spot lesions formed on human enamel under microcosm biofilm for different experimental periods

Abstract The initial characteristics of white spot lesion (WSLs), such as the degree of integrated mineral loss (ΔZ), depth and pattern of mineral distribution, have an impact on further demineralization and remineralization. However, these lesion parameters have not been evaluated in WSLs produced from microcosm biofilms. Objective: This study characterized artificial white spot lesions produced on human enamel under microcosm biofilm for different experimental periods. Methodology: In total, 100 human enamel specimens (4x4mm) were assigned to 5 distinct groups (n=20/group) differing according to the period of biofilm formation (2, 4, 6, 8 or 10 days). Microcosm biofilm was produced on the specimens from a mixture of human and McBain saliva at the first 8h. Enamel samples were then exposed to McBain saliva containing 0.2% sucrose. WSLs formed were characterized by quantitative light-induced fluorescence (QLF) and transverse microradiography (TMR). Data were analyzed by ANOVA/Tukey or Kruskal-Wallis/Dunn tests (p<0.05). Results: A clear time-response pattern was observed for both analyses, but TMR was able to better discriminate among the lesions. Regarding QLF analysis, median (95%CI; %) changes in fluorescence ∆Z were -7.74(-7.74:-6.45)a, -8.52(-8.75:-8.00)ab, -9.17(-10.00:-8.71)bc, -9.58(-10.53:-8.99)bc and -10.01(-11.44:-9.72)c for 2, 4, 6, 8, and 10 days, respectively. For TMR, median (95%CI; vol%.µm) ∆Z were 1410(1299-1479)a, 2420(2327-2604)ab, 2775(2573-2899)bc, 3305(3192-3406)cd and 4330(3972-4465)d, whereas mean (SD; µm) lesion depth were 53.7(12.3)a, 71.4(12.0)a, 103.8(24.8)b, 130.5(27.2)bc, 167.2(39.3)c for 2, 4, 6, 8 and 10 days, respectively. Conclusion: The progression of WSLs formed on human enamel under microcosm biofilm can be characterized over 2-10 days, both by QLF and TMR analyses, although the latter provides better discrimination among the lesions.

Deformation behavior of normal human enamel: A study by nanoindentation.

Tooth enamel has an important mechanical function for human dental health, yet characterizing its mechanical properties is not trivial due to its complex nanoporous structures. We examined the distribution of hardness and modulus across the lingual-buccal enamel cross-section by nanoindentation. At the occlusal surface, the hardness and modulus of enamel were found to be 5.00 ± 0.22 GPa and 97.12 ± 2.95 GPa, respectively. At the area close to the enamel-dentine-junction (EDJ), the hardness and modulus were 3.72 ± 0.35 GPa and 76.83 ± 5.71 GPa, respectively. At the middle region in between the EDJ and the outer enamel layer, the hardness and modulus were found to be 4.23 ± 0.18 GPa and 87.62 ± 2.50 GPa, respectively. The surface and area underneath the nanoindent were analyzed using the following microscopy tools: Scanning Electron Microscopy, Focused Ion Beam imaging, and Transmission Electron Microscopy. The deformation mechanisms of enamel were found to be location dependent and influenced by changes in the chemical composition within enamel. The EDJ forms the interface between enamel and dentin. The deformation behavior differed at the EDJ, due to the increased organic phase at the interface. Within the intermediate enamel region, intra-rod cracks were formed at the center of enamel rods and propagated into the neighboring inter-rod region at deviated directions along the orientation of the local crystallites. At the outer enamel layer, crack propagation was constrained by the rigid structure surrounding the indented site. Most of the cracks were formed close to the surface. A significant amount of material was also pushed upwards and delaminated from the enamel surface of the indentation area.

Enhanced teeth whitening by nanofluidic transport of hydrogen peroxide into enamel with electrokinetic flows.

Tooth whitening, a routine procedure in dentistry, is one of the examples of medical procedures that are limited by the challenge of delivering molecules into various types of nanoporous tissues. Current bleaching methods rely on simple diffusion of peroxides into enamel nano channels, therefore requires sufficient contact time with peroxides. In-office treatments often involve enamel etching or light activation which often results in patient sensitivity and potential soft tissue damage. OBJECTIVE: To demonstrate a robust method to transport hydrogen peroxide to greater depths into enamel nanopores through nanofluidic flows driven by electrokinetics, with the intention to increase efficacy while reducing treatment time. METHODS: Freshly extracted human teeth were subjected to electrokinetic flow treatment with hydrogen peroxide under different electric fields with varying operation times. Pre- and post-operative shade matching was done using a photospectrometer. RESULTS: It is demonstrated that the operation time for the same concentration of hydrogen peroxide can be shortened by 10 times. The proposed method showed significant improvements in whitening effects over control groups and thus offers promising clinically-viable chairside applications with efficacy. SIGNIFICANCE: The demonstrated nanofluidic transport of hydrogen peroxide into enamel has a potential to be applied for enhancing tooth whitening, compared to simple diffusion, without heating the hard dental tissues.

Effect of a stannous fluoride toothpaste on dentinal hypersensitivity: In vitro and clinical evaluation.

BACKGROUND: The authors conducted an in vitro and a clinical study to assess the effect of a toothpaste containing stannous fluoride to occlude dentin tubules and reduce dentinal hypersensitivity. METHODS: For the in vitro study, the authors treated the surface of human dentin specimens with test or control toothpaste slurries and then evaluated them by using various spectroscopic techniques. For the clinical study, male and female participants who met the inclusion criteria brushed their teeth twice daily for 1 minute with test or control toothpaste. The authors assessed dentinal hypersensitivity by using tactile and air blast stimuli at baseline and after 4 and 8 weeks. All statistical tests of hypotheses were 2 sided, with a significance level of α set at .05. RESULTS: Results from in vitro studies showed that the test toothpaste effectively occluded the dentinal tubules with a deposit consisting of tin, zinc, phosphate, and silicon. The test and control toothpastes occluded the tubules 82% and 35%, respectively. Clinically, at the 4- and 8-week examinations, the test toothpaste provided statistically significant (P < .001) improvements in tactile dentinal hypersensitivity scores of 27.8% and 42.0% and in air blast hypersensitivity scores of 21.4% and 32.3%, respectively, relative to the control toothpaste. CONCLUSIONS: The in vitro results indicate the toothpaste containing 0.454% stannous fluoride effectively coated dentin surfaces and occluded patent dentin tubules. Compared with the control toothpaste, the test toothpaste provided a significant reduction in dentinal hypersensitivity after 8 weeks of product use. PRACTICAL IMPLICATIONS: A multi-benefit option for patients with dentinal hypersensitivity.

Efficacy of two fluoride-free, alcohol-free mouthwashes containing 0.075% or 0.07% CPC in controlling established dental plaque and gingivitis over a 6-week period on adults in Puerto Rico.

PURPOSE: To evaluate the clinical efficacy of two commercially available, fluoride-free, alcohol-free mouthwashes containing either 0.075% or 0.07% cetylpyridinium chloride (CPC) in controlling established dental plaque and gingivitis compared to a non-antibacterial control mouthwash. METHODS: A 6-week double-blind, randomized clinical trial was conducted in Trujillo Alto, Puerto Rico. Recruited subjects were randomly assigned to one of three treatment groups: (1) a fluoride-free, alcohol-free mouthwash containing 0.075% CPC (TG); (2) a fluoride-free, alcohol-free mouthwash containing 0.07% CPC (PC); and (3) a fluoride-free, alcohol-free mouthwash without antibacterial agent (NC). Subjects were instructed to rinse with the assigned mouthwash, after tooth brushing, twice daily (morning and evening). After 4 and 6 weeks of product use, subjects were examined for gingivitis (Whole Mouth Gingival, Gingival Interproximal, Gingival Severity Indexes) and plaque (Whole Mouth Plaque, Plaque Interproximal, and Plaque Severity Indexes) parameters. ANCOVA and post hoc Tukey's pair-wise comparisons (α = 0.05) were performed for treatment group comparisons. RESULTS: A total of 132 subjects were screened; 120 were enrolled; and 116 completed the study. After 6 weeks of product use, participants who rinsed with the CPC-containing mouthwashes exhibited statistically significant (P < 0.05) reductions in all the gingivitis and plaque parameters evaluated, whereas in those using the non-antibacterial mouthwash, significant reductions were only observed in whole mouth and interproximal plaque scores. No statistically significant (P > 0.05) differences were observed, with respect to the gingival and plaque parameters, between the two CPC-containing mouthwashes.

Efficacy of CPC and essential oils mouthwashes compared to a negative control mouthwash in controlling established dental plaque and gingivitis: A 6-week, randomized clinical trial.

PURPOSE: To evaluate the clinical efficacy of a mouthwash containing 0.075% cetylpyridinium chloride (CPC) in a fluoride-free, alcohol-free base and a mouthwash containing essential oils in a fluoride-free, 21.6% alcohol base as compared to a fluoride-free, alcohol-free non-antibacterial mouthwash in controlling established dental plaque and gingivitis after 6 weeks of twice daily use. METHODS: A 6-week, parallel-group, randomized double blind clinical trial was conducted in Santo Domingo, Dominican Republic. Recruited subjects were randomly assigned to one of three treatment groups: (1) a mouthwash containing 0.075% CPC in a fluoride-free, alcohol-free base (CPC); (2) a commercially-available mouthwash containing essential oils in a fluoride-free, 21.6% alcohol base (EO); or (3) a fluoride-free, alcohol-free non-antibacterial mouthwash (NC). Subjects were instructed to rinse with the assigned mouthwash, after tooth brushing, twice daily (morning and evening). After 4 and 6 weeks of product use, subjects were examined for gingivitis (Whole Mouth Gingival, Gingival Interproximal, Gingival Severity Indexes) and plaque (Whole Mouth Plaque, Plaque Interproximal, and Plaque Severity Indexes) parameters. For treatment group comparisons, ANCOVA and post hoc Tukey's pair-wise comparisons (α = 0.05) were performed. RESULTS: 132 subjects were screened; 120 were enrolled; and 116 completed the study. After 6 weeks of product use, subjects using the CPC and EO mouthwashes exhibited statistically significant (P < 0.001) reductions of all gingival and plaque measurements compared to subjects using the NC mouthwash. Subjects using the CPC mouthwash did not exhibit a statistically significant (P > 0.05) reduction with respect to gingival severity and all plaque measures (Whole, Interproximal, and Severity) when compared to EO mouthwash. Subjects using the CPC mouthwash exhibited statistically significant (P < 0.05) reductions in Gingival Index scores of 5.1% (P = 0.005), and Gingival Interproximal Index scores of 5.5% (P = 0.016) relative to subjects using the EO mouthwash. These reductions were not considered clinically significant.

Randomized clinical trial of two oral care regimens in reducing and controlling established dental plaque and gingivitis.

PURPOSE: To evaluate the efficacy of a test regimen (TR) integrating the use of a commercially available triclosan, PVM/MA copolymer, and sodium fluoride containing toothpaste, an alcohol-free, fluoride-free cetylpyridinium chloride (CPC) mouthwash, and a manual toothbrush with cheek and tongue cleaner compared to a negative control regimen (NCR) integrating a commercially available 0.76% sodium monofluorophosphate toothpaste, a manual toothbrush and a fluoride-free and alcohol-free non-antibacterial mouthwash in the reduction and control of established plaque and gingivitis after 4 weeks of product use. METHOD: A 4-week, two-cell, double-blind, parallel-group, randomized clinical study was conducted in Cedar Knolls, New Jersey, USA. Recruited subjects were randomly assigned to two regimens: (1) a commercially available toothpaste containing triclosan, PVM/MA copolymer, and 0.243% sodium fluoride, a manual toothbrush with cheek and tongue cleaner, and commercially available mouthwash containing 0.075% CPC in a fluoride-free and alcohol-free base (TR), or (2) a commercially available 0.76% sodium monofluorophosphate toothpaste, a manual toothbrush with rounded/polished bristles, and a fluoride-free and alcohol-free non-antibacterial mouthwash (NCR). Subjects were examined for dental plaque and gingivitis. Gingival, Gingival Severity, Gingival Interproximal, Plaque, Plaque Severity and Plaque Interproximal Index scores were calculated. For regimen comparison, independent t-test and ANCOVA analyses were performed. RESULTS: 130 subjects were screened; 120 enrolled; and 115 subjects completed the randomized clinical trial (RCT). After 4 weeks of product use, subjects using TR exhibited statistically significant (P < 0.001) reductions of 22.3%, 27.8% and 20.4% in mean Gingival, Gingival Severity and Gingival Interproximal Index scores, respectively, as compared to subjects using NCR. After 4 weeks of product use, subjects using TR exhibited statistically significant (P < 0.001) reductions of 28.2%, 60.7% and 27.6% in mean Plaque, Plaque Severity and Plaque Interproximal Index scores, respectively, as compared to subjects using NCR.

An imaging-based approach to the evaluation of xerostomia.

BACKGROUND AND OBJECTIVE: Goal was to evaluate the potential of in vivo optical coherence tomography (OCT) imaging to determine the response of patients with xerostomia to a dry mouth toothpaste versus fluoride toothpaste placebo. STUDY DESIGN/MATERIALS AND METHODS: Ten subjects with xerostomia participated in this double-blind, crossover, placebo-controlled study. After examination and OCT imaging, subjects used the first product for 15 days, followed by a 7-day washout period, and then they used the second product for 15 days. Data were acquired at 5-day intervals, also before and after the washout. RESULTS: Visual examination and tongue blade adhesion test did not reflect response to the product. Two imaging-based markers were identified: (i) In OCT images, epithelial thickness increased significantly (P < 0.05) after use of the dry mouth toothpaste, but did not change significantly (P > 0.05) after the use of a fluoride toothpaste and (2) Optical backscattering data showed progressive characteristic changes from baseline with use of the active product. CONCLUSIONS: In this pilot study using in vivo OCT imaging, it was possible to detect and measure oral epithelial response to the dry mouth product versus placebo in patients with xerostomia. CLINICAL IMPLICATIONS: This approach may permit site-specific assessment of xerostomia, individualized treatment planning and monitoring, and sequential mucosal mapping in patients with dry mouth.

API-IT-MS for measuring aroma release from dentifrice products using a device to simulate tooth brushing.

A mechanical tooth brushing device coupled to an atmosphere pressure ionization ion trap mass spectrometer (API-IT-MS) combination has been developed to study the influence of time and dilution on aroma release from a model dentifrice system. API-IT-MS response to nine commonly used dentifrice flavor components was initially studied. Linear regression models were developed based on an exponential dilution method (EDA) to permit quantification of these compounds. Good linear fits were generated for the majority of compounds (R(2) > 0.92). The threshold detection limits were also calculated, and they greatly depended on the type of aroma compound. A brushing device was then coupled to the API-IT-MS and used to monitor the release profile of three aroma components from a model dentifrice system at flavor concentrations ranging from 0.1 to 20 mg g(-1). Large differences in the aroma release patterns were observed for different compounds (limonene, menthone and cinnamic aldehyde) that depended on their physicochemical characteristics (vapor pressure and log P), and on additional factors such as aroma-matrix interactions. In addition, a linear increase in API-IT-MS response with increased flavor concentration up to 1 mg g(-1) flavor was observed, while at higher concentrations, e.g. between 1 and 20 mg g(-1), a plateau in response was noticed. This suggests that at concentrations above 1 mg g(-1) a transition from a purely dissolved state to an emulsified state occurred. This fact influenced the time-dependent characteristics of the release curve (I(max) and t(max)) for the three assayed flavor compounds.

Bacterial plaque retention on oral hard materials: effect of surface roughness, surface composition, and physisorbed polycarboxylate.

Bacterial adhesion to oral hard materials is dependent on various factors, for example, surface roughness and surface composition. In this study, bacteria retention on three oral hard substrates, hydroxyapatite (HAP), enamel, and polished enamel (p-enamel) were investigated. The surface morphology and roughness of the three substrates were measured by scanning probe microscopy. HAP had the roughest surface, followed by enamel and polished enamel. For each individual substrate type, the roughness was shown to increase with scan size up to 50 microm x 50 microm. For HAP and enamel, roughness decreased considerably after formation of a pellicle, while addition of polymer coating to the pellicle layer reduced roughness much less in comparison. Bacterial surface coverage was measured at 30 min, 3 h, and 24 h on both native and surface-modified substrates, which were coated with two different polycarboxylate-based polymers, Gantrez S97 and Carbopol 940. As a result, the polymer coated surfaces had reduced bacteria coverage compared with the native surfaces over all time points and substrates measured. The reduction is the combined effect of electrostatic repulsion and sequestering of Ca(2+) ions at the surface, which plays a key role in the initial adhesion of bacteria to enamel surfaces in models of plaque formation.

In vitro efficacy of Colgate Total advanced fresh.

Generally, clinical studies using organoleptic judges, gas chromatography, or a sulfide monitor have been employed in the assessment of treatments for the control of oral malodor. However, these studies can be expensive and time consuming. Also, for agents whose safety has not been proven, these methods are not appropriate. Therefore, in vitro assessment is a critical step toward developing a new technology or implementing changes to an existing formula. The in vitro methods employed in this study combined basic microbiology methods, such as growth inhibition and zone of inhibition experiments. In addition, a newly developed, in vitro, volatile sulfur compounds (VSC) experiment that combined the essential elements of zone of inhibition, head space analysis, and dynamic flow cell techniques was also employed. The in vitro VSC method has been validated using technologies clinically proven to control oral malodor. All in vitro experiments have demonstrated that Colgate Total Advanced Fresh toothpaste has efficacy similar to that of the original Colgate Total toothpaste and that both variants showed superior efficacy to the control toothpaste. These results have been corroborated by clinical study results.

Clinical efficacy of Colgate Total Advanced Fresh and a commercially available breath-freshening dentifrice in reducing mouth-odor-causing bacteria.

The objective of this double-blind clinical study was to compare the long-lasting overnight (10- to 12-hour) and 4-hour effects of Colgate Total Advanced Fresh toothpaste to a commercial fluoridated breath-freshening dentifrice in controlling the level of mouth-odor-causing bacteria. Thirty-two adult men and women from New Jersey participated in the randomized, crossover design clinical study. After a 1-week "washout" period of brushing with a regular fluoride dentifrice, subjects refrained from dental hygiene, eating, and drinking in preparation for the morning visit. After providing a baseline salivary sample, subjects were issued a soft-bristled toothbrush and instructed to brush their teeth twice a day (once in the morning and once before bed) for 1 minute with the assigned test dentifrice. After a 7-day product use cycle, the subjects returned to the test site, having refrained from dental hygiene, eating, and drinking. Subjects provided an overnight salivary sample (10 to 12 hours postbrushing). Subjects then ate, brushed for 1 minute with the assigned dentifrice, and returned for 2- and 4-hour postbrushing evaluations. Subjects refrained from dental hygiene, eating, or drinking during the 4-hour evaluation period. To collect the oral microflora samples, subjects rinsed with 10 mL of sterile water for 10 seconds and deposited their samples into sterile tubes. Each collected sample was serially diluted in sterile phosphate-buffered saline and duplicate-plated onto lead acetate agar. When plated onto this medium, mouth-odor-causing bacteria that produce hydrogen sulfide appear as dark pigmented colonies. After 96 hours of incubation, hydrogen-sulfide-producing bacteria were counted, expressed as log colony-forming units per milliliter, and reduction from baseline was calculated. The results of this clinical study support the conclusion that Colgate Total Advanced Fresh provides a significantly greater reduction in mouth-odor-causing bacteria than a commercial fluoridated breath-freshening dentifrice (P < or = 0.05).