In vitro radiographic density of dental posts measured by digital radiography

Objectives

This study evaluated the radiopacity of seven commercial root canal posts.

Methods

Digital radiographs of the seven commercial posts and of the same commercial posts and four artificial aluminum posts inserted in lower canines were obtained with a CCD-based digital sensor. The radiopacity of the posts was expressed as mm aluminum/mm material (mmAl). Subsequently, the radiographs were presented to five trained evaluators who were asked to rank their acceptability scores as not acceptable, acceptable, or excellent.

Results

Analysis of variance revealed significant differences in radiopacity among the posts (P < 0.05). The radiopacities of zirconium and titanium posts were significantly higher than those of fiber posts (P < 0.05). The minimum aluminum thickness for acceptance in the root canals was 1.2 mmAl.

Conclusions

All of the examined posts presented satisfactory radiopacity for clinical application.     

Radiopacity and Cytotoxicity of Portland Cement Containing Zirconia Doped Bismuth Oxide Radiopacifiers

Introduction

This study evaluates the radiopacity and cytotoxicity of Portland cements containing a radiopacifier of bismuth oxide (Bi₂O₃) with yttria-stabilized zirconia (YSZ) dopant.

Methods

Various radiopacifier powders of Bi₂O₃ with 0%, 15%, 30%, and 100% YSZ dopant were prepared by solid-state reaction at 700°C for 12 hours and characterized by x-ray diffraction. Portland cement/radiopacifier/calcium sulfate (75/20/5) were mixed and set by deionized water. Changes in radiopacity and in vitro cell viability of the hydrated cements were assessed. An average of 6 measured equivalent thickness of aluminum (N = 6) capable of producing similar radiographic density was recorded. The cytotoxicity of each material was determined in MC3T3 E1 cell-based methyl-thiazol-tetrazolium assay.

Results

The x-ray diffraction patterns of YSZ doped Bi₂O₃ are different from those of pure Bi₂O₃ and YSZ. The cement-containing radiopacifier of Bi₂O₃/YSZ (85/15) presented significantly greater radiopacity (P < .05) compared with pure Bi₂O₃. The mouse osteoblastic cell (MC3T3-E1) viabilities of these 2 groups were statistically similar (P < .05).

Conclusions

The radiopacifier of Bi₂O₃/YSZ (85/15) reveals higher radiopacity but similar cell viability when compared with pure Bi₂O₃. It shows potential use as an alternative radiopacifier in root-end filling materials.     

The Radiopacity and Antimicrobial Properties of Different Radiopaque Double Antibiotic Pastes Used in Regenerative Endodontics

Introduction

We evaluated the radiopacity and antibacterial properties of various concentrations of double antibiotic paste (DAP) containing barium sulfate (BaSO₄) or zirconium oxide (ZrO₂) radiopaque agents.

Radiopacity of dental restorative materials

Objectives

Radiopacity of dental materials enables clinician to radiographically diagnose secondary caries and marginal defects which are usually located on the proximal gingival margin. The aim of this study was to measure the radiopacity of 33 conventional resin composites, 16 flowable resin composites, and 7 glass ionomer cements and to compare the results with the radiopacity values declared by the manufacturers.

Materials and methods

From each restorative material, six 2-mm-thick disk-shaped specimens were fabricated and eight 2-mm-thick sections of teeth were made and used as reference. The material samples and tooth sections were digitally radiographed together with the aluminum stepwedge. Gray values were obtained from the radiographic images and radiopacity values were calculated and statistically analyzed. Post hoc Tukey’s honestly significant difference test was used to calculate significant differences in radiopacity values between materials and reference dentin and enamel values.

Results

The radiopacity values of all 56 restorative materials were above the dentin reference radiopacity value; however, 4 out of 33 conventional composites and 3 out of 16 flowable resin composites had significantly lower radiopacity than enamel (p?<?0.05). There were up to 1.53 mm eq Al differences between the measured and the manufacturers’ declared radiopacity values of some materials.

Conclusions

Majority of the materials exceed enamel radiopacity and would not hamper radiographic diagnosis of secondary caries. However, manufacturers’ data are not always reliable.

Clinical relevance

Materials with radiopacity lower than enamel might be misinterpreted as secondary enamel caries on radiographic images, especially when applied as initial increment on the proximal gingival margin.     

Bleaching effectiveness,hydrogen peroxide diffusion,and cytotoxicity of a chemically activated bleaching gel

Objectives

The objective of this study was to evaluate the bleaching effectiveness, hydrogen peroxide diffusion (H₂O₂), and cytotoxicity of a bleaching gel with 35 % H₂O₂ either associated with ferrous sulfate (FeSO₄) or not.

Materials and methods

Enamel/dentin discs adapted to artificial pulp chambers were placed in compartments containing a culture medium (Dulbecco's Modified Eagle's Medium (DMEM)) and distributed into the following groups: G1—no treatment (negative control), G2—10 % carbamide peroxide (one application for 4 h), G3—35 % H₂O₂ (three applications for 15 min), and G4—35 % H₂O₂ + 0.004 g FeSO₄ (three applications for 15 min). After treatments, the extracts (DMEM + bleaching components that diffused across enamel and dentin) were applied on human dental pulp cells (HDPCs) and odontoblast-like cells (MDPC-23). Cell viability (MTT assay, Kruskal–Wallis and Mann–Whitney, α?=?5 %), quantification of H₂O₂ diffusion, and color change of the enamel/dentin discs (Commission Internationale de I'Eclairage L*a*b* system) were assessed (analysis of variance and Tukey's tests, α?=?5 %).

Results

For both cells, a significant reduction in cell viability was observed for G3 and G4 compared with G1 and G2. No statistical difference was observed between G3 and G4. The rate of H₂O₂ diffusion was significantly higher in G3 compared with that in G2 and G4. The ΔE value for G4 was statistically higher than that of the other groups.

Conclusions

Chemical activation of H₂O₂ by FeSO₄ improves the bleaching effectiveness. However, this metal ion has no significant protective effect against pulp cell cytotoxicity.

Clinical relevance

Although the chemical activation of H₂O₂ by adding FeSO₄ to the bleaching agent improved the bleaching effectiveness, this metal ion has no significant protective effect against pulp cell cytotoxicity.     

Maxillary distraction osteogenesis at Le Fort-I level induces bone apposition at infraorbital rim

Objective

The aim of this study is to evaluate whether there is any remodeling of bone at infraorbital rim following maxillary distraction osteogenesis (DO) at Le Fort-I level.

Materials and methods

Twelve adult subjects in the age range of 17–21 years with complete unilateral cleft lip and palate underwent advancement of the maxilla by DO. The effect of maxillary DO on the infraorbital rim remodeling was evaluated from lateral cephalograms recorded prior to the DO (T₀), at the end of DO (T₁), and at least 2-years after the DO (T₂) by Walker’s analysis. The ANOVA and two-tailed t test were used and probability value (P value) 0.05 was considered as statistically significant level.

Results

There was anterior movement of maxilla by 9.22?±?3.27 mm and 7.67?±?3.99 mm at the end of immediate (T₁) and long-term (T₂) follow-up of maxillary DO, respectively. The Walker’s analysis showed 1.49?±?1.22 mm and 2.31?±?1.81 mm anterior movement of the infraorbital margin (Orbitale point) at the end of T₁ and T₂, respectively (P?Conclusion The advancement of maxilla by distraction osteogenesis at Le Fort-I level induced significant bone apposition at infraorbital rim.

Clinical relevance

Patients with mild midface hypoplasia who would otherwise may be candidates for osteotomy at Le Fort-II or Le Fort-III level may benefit from maxillary distraction at Le Fort-I level.     

Assessment of genotoxic effect of maleic acid and EDTA: a comparative in vitro experimental study

Objectives

This study aims to evaluate and compare the genotoxic and apoptotic effect of aqueous solutions of ethylenediaminetetraacetic acid (EDTA) with that of maleic acid (MA) using Chinese hamster lung fibroblast (V79) cells growing in vitro.

Materials and methods

Exponentially growing V79 cells were treated with various concentrations of EDTA or MA alone for 30 min, and genotoxic effect was analyzed by micronucleus as well as comet assays and the type of cell death by apoptotic cell measurements using microscopic and flow cytometric methods. For all the experiments, H₂O₂ was used as a positive control.

Results

Treatment of V79 cells with H₂O₂ resulted in significantly (P?<?0.001) increased micronuclei and levels of DNA damage, whereas, EDTA/MA alone treated cells did not show significant increase of MN frequencies and comet parameters even at their higher concentrations when compared with that of untreated control. V79 cells treated with EDTA/MA for 30 min showed a nonsignificant increase in the percentage of apoptotic and necrotic cells at their lower concentrations (0.025 and 0.05 % for EDTA and MA, respectively). However, at higher concentrations, i.e., >IC₅₀ (0.1 and 0.5 %) for EDTA and MA resulted in increased number of apoptotic and necrotic cells when compared with the untreated group.

Conclusions

This study clearly demonstrates that MA and EDTA are not potentially genotoxic agents and MA induced lesser apoptotic/necrotic death than that of EDTA at their clinically relevant doses.

Clinical relevance

MA may have a better clinical acceptability with comparable smear layer removal ability. Hence, the results presented here might be an additional supporting evidence for the use of MA in endodontic practice.     

Effect of nonsurgical periodontal therapy (with or without oral doxycycline delivery) on glycemic status and clinical periodontal parameters in patients with prediabetes: a short-term longitudinal randomized case–control study

Objective

The aim of the present short-term longitudinal randomized case–control study was to assess the effect of nonsurgical periodontal therapy (NSPT) (with and without oral doxycycline delivery) on glycemic status and clinical periodontal parameters in patients with prediabetes.

Material and methods

Sixty-six patients with prediabetes and periodontal disease were included. Characteristics of the study cohort (age, gender, socioeconomic status [SES] education status, duration of prediabetes, and type of treatment adopted for prediabetes management) were recorded. Patients were randomly divided into two groups (33 patients/group). In group 1, scaling and root planing (SRP) was performed, and in group-2, patients underwent SRP and oral doxycycline (100 mg) administration once daily for 15 days. In each group, the following parameters were investigated at baseline and after 3 months: (a) fasting blood glucose level (FBGL), (b) hemoglobin A1c (HbA1c), and (c) periodontal parameters (plaque index [PI], bleeding on probing [BOP], probing depth [PD], and clinical attachment loss [AL]). Statistical analysis was performed using Student’s t test.

Results

There was no significant difference in age, gender, SES, education status, and duration and treatment of prediabetes among individuals in groups 1 and 2. Three months post-NSPT, FBGL and HbA1c were significantly reduced among patients in group 1 (P?P?P?P?P?P?P?Conclusion NSPT (with and without oral doxycycline delivery) reduces hyperglycemia and periodontal inflammation in patients with prediabetes.     

Pretreatment of natural caries lesions affects penetration depth of infiltrants in vitro

Objectives

Limited evidence exists about the usefulness of ethanol or acetone application to desiccate caries lesions before resin infiltration. Therefore, this in vitro study aimed to compare the penetration depths (PD) of an infiltrant (DMG, Germany) into natural caries lesions using various pretreatments.

Material and methods

Extracted permanent human molars and premolars showing non-cavitated caries lesions were etched (90 s, 15 % HCl gel) and stored in pooled saliva (7 days). Lesions were etched again (30 s, 15 % HCl gel), washed (30 s), air-dried (30 s), and randomly allocated to one of the pretreatments: none (negative control), air-drying (incubator, 37 °C, 24 h; positive control), once ethanol (E1), twice ethanol (E2), once acetone (A1), and twice acetone (A2). Subsequently, the infiltrant was applied for 5 min and light-cured. Ground sections were prepared for analyses of lesion depths (LD) and PD using confocal microscopy.

Results

Median LD (Q25/Q75) of all lesions (n?=?91) and lesions ≥500 μm (n?=?57) were 629 (395/798) and 731 (638/876)?μm, respectively. When all lesions were analyzed, no significant differences between various pretreatments could be observed (p?>?0.05, Kruskal–Wallis). For lesions ≥500 μm, significantly deeper PP was observed in groups PC, E1, A1, and A2 compared with NC (p?<?0.05; Mann–Whitney), but not after adjustment for multiple comparison (p?>?0.05).

Conclusion

Application of either ethanol or acetone, followed by air-drying, is suitable to prepare caries lesions for resin infiltration in vitro.

Clinical relevance

This paper shows that proper drying is an important step prior to caries infiltration.     

Electromyographic activity of the masseter muscle after radiofrequency therapy in an animal model

Purpose

The purpose of this study was to examine changes in the electromyographic (EMG) activity of the masseter muscle after radiofrequency therapy (RF).

Methods

Twelve rabbits were used in this study: four in each group according to the number of RF applications. Preoperative EMG in the masseter muscle was used as the control. EMG was recorded at 1, 2, 3, and 4 weeks after RF in each rabbit. The recorded data were analyzed in terms of voltage and frequency, and changes in recorded variables were compared among the groups. The relative activity in peak voltage, root mean square of the action potential, area of voltage, and area of frequency were investigated.

Results

When compared to preoperative values, the variables at 3 or 4 weeks after RF application were significantly different in the single and quadruple therapy groups (P?<?0.05). There was no significant difference in the other groups (P?>?0.05). When the samples were regrouped as two groups like small number of application group (one or two point) and large number of application group (three or four points), the area of voltage and the area of frequency were significantly different between the groups at 4 weeks (P?<?0.05).

Conclusions

Masseter muscle activity after RF was significantly decreased compared to its preoperative state. The decreased activity was related to the number of applications and time elapsed after RF.     

Immunohistochemical characteristics of regenerated bone after surgical therapy of advanced ligature-induced peri-implantitis defects

Objectives

This study seeks to assess and compare immunohistochemical characteristics of regenerated and pristine bone areas following surgical therapy of advanced peri-implantitis.

Methods

At ligature-induced peri-implantitis defects, the intrabony component was filled with a natural bone mineral (NBM), and the supracrestal component was treated by either an equine bone block (EB) or implantoplasty. NBM and EB were soak-loaded with rhBMP-2 or sterile saline. Membrane (i.e., native collagen) protected sites were submerged for 12 weeks. Osteocalcin (OC) and transglutaminase 2 (TG2; angiogenesis) antigen reactivity was assessed within the augmented- (AA) and pristine bone (PB) areas at non-exposed sites (n?=?39 defects).

Results

In all groups investigated, mean OC (AA, 0.5?±?0.4 to 1.9?±?2.9 %/PB, 1.7?±?2.6 to 3.5?±?6.5 %) and TG2 (AA, 0.6?±?0.5 to 1.3?±?1.5 %/PB, 0.5?±?0.5 to 1.6?±?1.9 %) values within AA did not significantly differ from those values assessed within PB (P?>?0.05, respectively).

Conclusions

AA formed in different treatment groups may not be considered as qualitatively (i.e., OC and TG2) compromised bone.     

Evaluation of the long-term storage stability of saliva as a source of human DNA

Objectives

The objectives of this paper are to determine the storage stability of saliva at 37 °C over an 18-month period, and its influence on the DNA yield, purity, PCR protocols and genotyping efficacy.

Materials and methods

Of the 60 participants, blood samples were obtained from 10 and saliva from 50. Samples were subjected to different storage conditions: DNA extracted immediately; DNA extracted following storage at 37 °C for 1, 6, 12 and 18 months. Subsequently, DNA yield, OD_260/280 and OD_260/230 ratios were measured. The isolated DNA was used to amplify exons 0–7 of the RUNX2 gene and subsequently sequenced. Furthermore, 25 SNPs were genotyped.

Results

The mean DNA yield, OD_260/280 and OD_260/230 ratios obtained from blood were 67.4 ng/μl, 1.8?±?0.05 and 1.8?±?0.4 respectively. DNA yield obtained from saliva was significantly higher than blood (p?<?0.0001), ranging from 97.4 to 125.8 ng/μl while the OD_260/280 ratio ranged from 1.8?±?0.13 to 1.9?±?0.1. The success rates for the 25 SNPs ranged from 98 to 100 % for blood and 96–99 % for saliva samples with the genotype frequencies in Hardy–Weinberg equilibrium (>0.01).

Conclusions

Saliva can be stored at 37 °C for 18 months without compromising its quality and ability to endure genetic analyses.

Clinical relevance

Saliva is a viable source of human DNA to facilitate the feasibility of large-scale genetic studies.     

Two-year clinical evaluation of composite resins in non-carious cervical lesions

Objective

The purpose of this double-blind, randomised trial was to compare the clinical performance of a hybrid composite (Clearfil AP-X, Kuraray, Tokyo) and a nanocomposite (Filtek Z350, 3M ESPE, St. Paul, MN) over a period of 2 years in non-carious class V lesions using a modified US Public Health Service (USPHS) system.

Methods

Forty-six patients with at least one pair of equivalent non-carious cervical lesions under occlusion and a mean age of 44.1 years (range 27–66 years; median 45 years) were enrolled in this study. A total of 116 restorations (58 with each material) were placed according to manufacturer's instructions by two calibrated operators. The restorations were evaluated at baseline and at 6, 12 and 24 months after placement using the USPHS criteria for retention, colour match, marginal discolouration, marginal adaptation, anatomic form, surface texture and secondary caries. Statistical analysis was conducted using the Cochran and the McNemar tests at a significance level of 5 % (P?<?0.05).

Results

No surface texture changes or secondary caries were detected in association with any restorations. The retention rates for Clearfil AP-X (100 %) and for Filtek Z350 (91.38 %) did not differ significantly (P?>?0.05). Two Z350 restorations were completely lost after 2 years. No significant differences were observed in the colour match, marginal discolouration, marginal adaptation or anatomic form.

Conclusions

There were no significant differences in the clinical performances between the materials.

Clinical relevance

Both restorative materials exhibited acceptable clinical performance in class V non-carious lesions 2 years post-restoration.     

Proliferation and osteogenic differentiation of osteoblast-like cells obtained from two techniques for harvesting intraoral bone grafts

Objectives

The aims of our study were to verify the presence of viable osteoblasts in samples of bone tissue obtained by drilling or from cortico-cancellous bone blocks and to assess their growth and differentiation capacities.

Materials and methods

Bone tissue samples were processed independently and cultured in Dulbecco’s modified Eagle medium, in a CO₂ incubator at 37 °C. The proliferative capacity of osteoblasts was determined by spectrophotometry (MTT) at 24 and 48 h of culture. Cell cycle was analysed by flow cytometry. Cell differentiation was studied by red alizarin staining of nodules formed in mineralisation medium and by analysis of alkaline phosphatase activity.

Results

In comparison to bone block-derived osteoblasts, the proliferative capacity was greater at 24 and 48 h of culture (P?<?0.001) in the drilling-derived osteoblasts, which showed significantly increased G2/M (P?=?0.014) and S (P?<?0.001) phases in the cell cycle study. The number of mineralised nodules was proportional to the incubation time, with no differences between the two types of sample, which also did not significantly differ in alkaline phosphatase activity.

Conclusion

Superior autograft material is obtained by harvesting particulate bone from low-speed drilling fragments than from a cortico-cancellous bone block.

Clinical relevance

These results suggest that bone obtained from low-speed drilling is a simple and effective alternative to the classic procedure for obtaining bone tissue.     

Clinical and microbiological changes after minimally invasive therapeutic approaches in intrabony defects: a 12-month follow-up

Objectives

This 12-month randomized, controlled trial evaluated the clinical effects and microbiological changes of minimally invasive nonsurgical and surgical approaches for the therapy of intrabony defects.

Materials and methods

Twenty-nine subjects with intrabony defects in single-rooted tooth were randomly assigned to; (1) minimally invasive nonsurgical technique (MINST) or (2) minimally invasive surgical technique (MIST). Quantities of Aggregatibacter actinomycetemcomitans, Tannerella forsythia, and Porphyromonas gingivalis, determined by using real-time PCR, were evaluated at baseline, 3, 6, and 12 months after the treatments. Clinical recordings—probing depth (PD), position of the gingival margin (PGM), and relative clinical attachment level (RCAL)—were obtained at baseline and 12 months post-therapy. The primary outcome variable of the study was RCAL.

Results

Both treatment modalities resulted in an improvement in all clinical recordings, with significant PD reductions (p?<?0.05), RCAL gains (p?<?0.05), and no change in the PGM (p?>?0.05) after 12 months in both MINST and MIST groups. No clinical differences were observed between groups (p?>?0.05). Regarding the microbiological outcomes, at the re-examinations, a significant decrease was observed for T. forsythia and P. gingivalis when compared with baseline (p?<?0.05) for both treatments. The amount of A. actinomycetemcomitans did not reduced decrease throughout the study (p?>?0.05). Intergroup differences in the microbiological assay were not found at any time point (p?>?0.05).

Conclusions

Both MINST and MIST provided comparable clinical results and microbiological changes in the treatment of intrabony defects over 12 months follow-up.

Clinical relevance

This randomized, controlled, parallel trial revealed that both therapeutic modalities may promote clinical and microbiological benefits at 12 months post-therapy.     

Effect of fluoride gels supplemented with sodium trimetaphosphate in reducing demineralization

Objectives

The objective of this study was to evaluate the in vitro effect of low-fluoride (F) gels supplemented with sodium trimetaphosphate (TMP) on enamel demineralization.

Materials and methods

Bovine enamel blocks (n?=?160) were selected based on surface hardness (SH) and divided into eight treatment groups (n?=?20 per group): no F or TMP (placebo), 3 % TMP (3 %TMP), 5 % TMP (5 %TMP), 4,500 μg F/g (4,500), 4,500 μg F/g?+?3 % TMP (4,500 3 %TMP), 4,500 μg F/g?+?5 % TMP (4,500 5 %TMP), 9,000 μg F/g (9,000), and 12,300 μg F/g (acid gel). Blocks were subjected to demineralization/remineralization cycling for 5 days. Subsequently, surface hardness (SH₁) and integrated loss of subsurface hardness (ΔKHN) were assessed, and the concentrations of loosely bound (CaF₂-like) and firmly bound (FA-like) formed and retained F were determined.

Results

The 4,500 5 %TMP and acid gel groups showed similar results and had the lowest mineral loss (SH₁ and ?KHN). The acid gel group had the highest concentration of CaF₂-like F, but the formation and retention of FA-like F was greater in the 4,500 5 %TMP group than in the acid gel group (p?<?0.05).

Conclusion

It is possible to inhibit enamel demineralization with low-F gels supplementing these gels with 5 % TMP.

Clinical relevance

The low-F gel containing TMP can be regarded as a safer alternative for clinical use from a toxicological point of view since it contains half of the amount of a conventional formulation while promoting similar anticaries effect.     

Lactobacillus paracasei SD1, a novel probiotic,reduces mutans streptococci in human volunteers: a randomized placebo-controlled trial

Objectives

The present study investigates the effect of an oral Lactobacillus paracasei SD1 isolate on a number of salivary mutans streptococci, lactobacilli, and yeasts and to examine whether the strain could persist in the oral cavity after a short period of consumption. The potential side effect of the probiotic was also evaluated.

Material and methods

After informed consent, 40 healthy young adults were recruited and randomly assigned to either the test (A) or placebo (B) groups. Group A received milk powder contained L. paracasei SD1, and group B received standard milk powder once daily for 4 weeks. Salivary mutans streptococci, lactobacilli, and yeasts were enumerated using quantitative differential culture at the baseline and then once a week for 4 weeks after the administration period. The persistence of L. paracasei SD1 was also investigated using AP-PCR for the DNA fingerprinting.

Results

A statistically significant reduction in mutans streptococci counts occurred within group A compared to the baseline B (P?<?0.05) along with a non-statistically significant reduction in yeast counts. A significant increase in lactobacilli numbers occurred in group A (P?<?0.05), and the probiotic strain could be detected up to 4 weeks following cessation of dosing.

Conclusions

Our results demonstrate that short-term daily ingestion of the human-derived probiotic L. paracasei SD1 reduces the number of oral mutans streptococci.

Clinical Relevance

L. paracasei SD1 may help to decrease the risk of dental caries, and this organism may be a useful probiotic organism for dairy products.     

Chemometric analysis of the consumption of oral rinse chlorite (ClO2 −) by human salivary biomolecules

Objectives

Oral rinse formulations containing chlorite anion (ClO₂ ^?) as an active agent exert a range of valuable oral healthcare activities. However, salivary biomolecules which chemically react with this oxidant can, at least in principle, serve as potentially significant barriers to these therapeutic properties in the oral environment. Therefore, in this investigation, we have explored the extent of ClO₂ ^? consumption by biomolecules which scavenge this agent in human salivary supernatants (HSSs) in vitro.

Materials and methods

HSS samples were equilibrated with oral rinse formulations containing this active agent (30 s at 35 °C in order to mimic oral rinsing episodes). Differential spectrophotometric and ion-pair reversed-phase high-performance liquid chromatographic analyses were employed to determine residual ClO₂ ^? in these admixtures.

Results

Bioanalytical data acquired revealed the rapid consumption of ClO₂ ^? by biomolecular electron donors and/or antioxidants present in HSS samples. Mean?±?95 % confidence interval (CI) consumption levels of 7.14?±?0.69 and 5.34?±?0.69 % of the total ClO₂ ^? available were found for oral rinse products containing 0.10 and 0.40 % (w/v) ClO₂ ^?, respectively. A mixed model analysis-of-variance performed on experimental data acquired demonstrated highly-significant differences between oral rinse ClO₂ ^? contents (p?<?0.0001), trial participants (p?<?0.001) and sampling days–within-participants (p?<?0.001), and also revealed non-additive ClO₂ ^?-scavenging responses of participants’ HSSs to increases in the oral rinse content of this oxidant (p?<?0.0001). A slower, second phase of the reaction process (t _1/2?=?1.7–2.8 h) involved the oxidative consumption of salivary urate.

Conclusions

These data clearly demonstrate that for recommended 30 s oral rinsing episodes performed at physiological temperature, <10 % of the total oral rinse ClO₂ ^? available is chemically and/or reductively consumed by HSS biomolecules for both oral rinse formulations investigated.

Clinical relevance

These observations are of much clinical significance in view of the retention of these products’ active agent, i.e. <10 % of ClO₂ ^? is consumed by HSS biomolecules within recommended 30 s oral rinsing episodes, and hence, the bulk of this oxyhalogen oxidant (>90 %) may effectively exert its essential microbicidal, anti-periodontal and oral malodour-neutralising actions.     

Effects of high-fluoride dentifrice (5,000-ppm) on caries-related plaque and salivary variables

Objectives

The aim of the present study was to measure the effects of a 5,000-ppm F toothpaste on caries-related factors in dental plaque and saliva.

Materials and methods

A 6-week clinical trial was designed with a total of 34 participants, of which 26 completed the study. The participants were assessed on four visits, 2 weeks apart. Sampling of approximal fluid for fluoride analysis and approximal plaque for organic acid analysis was performed. Chair-side tests were performed to register the lactic acid production rate on the tongue using Clinpro? Cario L-Pop?, approximal plaque pH using the pH “strip method” and salivary buffer capacity and counts of cariogenic microorganisms using CRT Buffer® and CRT Bacteria®.

Results

Six weeks’ use of 5,000-ppm fluoridated (F) toothpaste significantly increased the approximal fluid F concentration (p?<?0.05). There was a significant decrease in lactic acid production rate on the tongue assessed by Clinpro? (p?<?0.05). This was accompanied by changes in interproximal plaque acidogenicity, including significant reductions in AUC_5.7, AUC_6.2 and maximum pH fall and an increase in minimum pH (p?<?0.05). A significant increase in the salivary buffer capacity and a reduction in the salivary mutans streptococci were observed (p?<?0.05).

Conclusion

The present study demonstrates the ability of 5,000-ppm F toothpaste to modify caries-related factors in dental plaque and saliva.

Clinical relevance

The 5,000-ppm F toothpaste could be regarded as a possible effective regimen against caries in the near future.