Biopsy-derived oral keratinocytes - A model to potentially test for oral mucosa radiation sensitivity.

Purpose: To establish stable in vitro growth of keratinocytes from very small biopsy specimens and successfully apply new test systems to determine their radiosensitivity. Materials and Methods: Oral mucosa biopsies (diameter: 1.7 mm) from 15 subjects were immobilized with custom-made cups onto culture plates. Outgrowing cells were tested for cytokeratin 5/14 and Ki67, expanded, radiated at different doses, and seeded onto circumscribed areas before being allowed to spread centrifugally. In this newly developed spreading assay, cell-covered areas were measured by image analysis. For statistical analysis, a linear mixed regression model was used; additionally, results were correlated to the radiation dose applied. Colony forming efficiency (CFE) was used to validate the results. DNA damage repair was analysed by gammaH2AX and 53BP1 foci quantification using immunofluorescence microscopy 24 h and 96 h after irradiation. Results: Stable keratinocyte growth continued for up to 7 weeks in 14 biopsies. Cells spread reliably from an initial 16.6 mm2 up to a median of 119.2 mm2 (range: 54.4-290). Radiated cells spread to only 100.7 mm2 (2 Gy; range: 55.3-266.7); 73.2 mm2 (4 Gy; 15-240.4); 47 mm2 (6 Gy; 2-111.9), and 22.7 mm2 (8 Gy; 0-80). Similarly, CFE decreased from 0.223 (0 Gy) to 0.0028 (8 Gy). Using an individual donor as a random factor, cell spread correlated with CFE, where radiation dose was the main driver (decrease by 0.50, adjusted for area). Upon irradiation with 6 Gy, radiation-induced DNA damage was increased after 24 h in all samples, and even after 96 h in 5 out of 7 samples, as detected by a higher number of gammaH2AX/53BP1 foci in irradiated cells (mean 3.7 for 24 h; mean 0.6 for 96 h). Conclusion: In vitro propagation of keratinocytes derived from a small biopsy is feasible. Radiation impairs cellular migration and proliferation, and the newly described spreading assay allows ranking for cellular radioresistance. The keratinocyte model also supports classical functional assays such as clonogenic survival and DNA double strand repair. The clinical relevance awaits upcoming investigations.

Red fluorescence of plaque in the dentition-a comparison of Quantitative Light-induced Fluorescence-Digital (QLF-D) images and conventional images of disclosed plaque.

BACKGROUND: Quantitative Light-induced Fluorescence-Digital (QLF-D) detects red fluorescence of plaque, but is almost solely used on labial anterior tooth surfaces. As distribution and formation of plaque varies distinctly within the dentition, our aim was to investigate, how red fluorescing plaque is related to disclosed plaque depending on tooth type and surface. This was done with habitual plaque and after de-novo plaque formation. METHODS: Thirty subjects were enrolled. QLF-Dimages of undisclosed plaque and conventional images of disclosed plaque were planimetrically analysed. Values were expressed as percentage of red fluorescing plaque (P%QLF-D) and of disclosed plaque (P%D) of the total tooth surface. Images were taken at baseline, after de-novo plaque formation (48 (T2) and 72 (T3) h without oral hygiene after professional tooth cleaning), and after 4-6 weeks of habitual oral hygiene (T4). RESULTS: At the tooth level, P%QLF-D was significantly lower than P%D on vestibular surfaces but reached similar levels on oral surfaces. De-novo plaque formation caused a significant increase in P%D on vestibular surfaces; this was not reflected by QLF-D. At the subject level, on vestibular surfaces and at baseline, some subjects exhibited minor but others gross differences between P%QLF-D and P%D. This was not the case at T3, but the same pattern appeared again at T4. On oral surfaces, the order of differences was more evenly scattered with no clear impact of the observation time point. CONCLUSION: Red fluorescence of dental plaque relates very differently to disclosed plaque depending on sites and maturation stages and has a significant inter-individual component.

Influence of the long-term use of oral hygiene products containing stannous ions on the salivary microbiome - a randomized controlled trial.

Oral hygiene products containing tin are suitable to prevent erosive tooth wear, yet effects on the oral microbiota are not known yet. Therefore, this study determined the salivary microbiome of 16 participants using products with stannous ions for three years (TG) compared with a control group (CG) to assess their influence on the microbiota. Participants were included in a randomized controlled clinical trial (RCT) with biannual visits. Illumina Miseq sequencing revealed as most abundant genera: Streptococcus (TG 14.3%; CG 13.0%), Veillonella (TG 11.3%; CG 10.9%), Prevotella (TG 7.0%; CG 9.8%), Haemophilus (TG 6.6%; CG 7.2%), Porphyromonas (TG 5.9%, CG 5.1%), Leptotrichia (TG 5.8%; CG 4.9%), Actinomyces (TG 4.0%; CG 4.6%) and Neisseria (TG 5.4%; CG 4.2%). Beta-Diversity was not significantly different between groups at both time points, although significant differences between groups were found for certain taxa after three years. The genus Prevotella was found in higher abundance in CG whereas Neisseria and Granulicatella, health-associated taxa, were found more abundantly in TG. Salivary microbiota after three years reflected a composition associated with oral health, hence continual use as a preventive measure for dental erosion can be considered safe and benefitting oral health for patients with a high risk of erosion.

Bond Stability of a Universal Adhesive System to Eroded/Abraded Dentin After Deproteinization.

OBJECTIVE: Erosive/abrasive challenges can potentially compromise bonding to dentin. Aiming to improve the quality and stability of bonding to this substrate, this study investigated the combined effect of erosion and toothbrush abrasion on the microtensile bond strength (µTBS) stability to dentin using a universal adhesive system in total and self-etching modes, associated or not associated with deproteinization. METHODS: Bovine dentin specimens were divided into five groups according to the organic matrix condition (n=20): control (C); erosion (E); erosion + abrasion (EA); erosion + sodium hypochlorite (EH); erosion + abrasion + sodium hypochlorite (EAH). The groups were further divided (n=10) according to the mode of application (total or self-etching) of a universal adhesive. After the bonding procedure, composite blocks were built up, and the samples were cut to obtain sticks for µTBS testing. For each specimen, one-half of the sticks was immediately tested, and the other one-half was tested after artificial aging (5000 thermocycles, 5°C and 55°C). RESULTS: Three-way analysis of variance (α=5%) showed a significant difference for the triple interaction ( p=0.0007). Higher µTBS means were obtained for the EH and EAH groups compared with the E and EA groups. The control group showed immediate µTBS values similar to that of the E and EA groups for both bond strategies. CONCLUSIONS: Erosion and erosion/abrasion did not significantly influence the immediate µTBS to dentin. Artificial aging reduced µTBS values for the groups C, E, and EA using the total-etching mode. Deproteinization maintained the bond stability to artificially aged eroded and eroded/abraded dentin.

Erosive tooth wear - a review on global prevalence and on its prevalence in risk groups.

Erosion is a common phenomenon in the general population of developed countries. However, due to variations in indices, sample sizes and general study designs, it is difficult to compare the various studies and to estimate actual global prevalence. Therefore, the aim of this present paper is to give a narrative overview on the data available on the global prevalence of erosion. Information on prevalence is not available from each country; in particular, data from Asia, Africa, South America, North America and large parts of South-Eastern Europe are unavailable. There is a large variation in global prevalence ranging between 0 and 100%. Calculating a rough mean from the data available, a mean prevalence in deciduous teeth between 30% and 50% and in permanent teeth between 20% and 45% can be estimated. There seems to be a gender difference and an increase in prevalence with age. Prevalence studies on erosion risk groups show comparable variation. Only in patients with gastro-oesophageal reflux disease (GORD) and eating disorders associated with vomiting can a clear impact on erosion prevalence be found. In people who consume acidic foods and drinks, a higher risk can be found for some specific comestibles. However, there is a lack of controlled epidemiological studies, making it difficult to generalise. There is a clear need for well-designed studies on this issue.

Tooth brushing motion patterns with manual and powered toothbrushes-a randomised video observation study.

INTRODUCTION: Systematic reviews have shown that powered toothbrushes (PTs) are more effective than manual toothbrushes (MTs), but with only minor effect sizes. Whether PTs are used adequately, however, has not been investigated so far. The aim of the present study was therefore to analyse motion habits with PT in comparison to MT toothbrushes by video observation. MATERIALS AND METHODS: One hundred subjects were enrolled in this observational trial and brushed their teeth in randomised order with a MT and PT while being video-filmed, resulting in 95 analysable sets of recordings. Parameters of interest were brushing duration (s; median (min;max)), type of brushing strokes, area of brushing, changes between areas (n; median (min;max)) and brushing sequence. RESULTS: Brushing duration was 145 s (60;354) and 135 s (48;271) for PT and MT, respectively (p ≤ 0.001). Subjects brushed vestibular surfaces completely, but reached oral surfaces to a much lesser extent, regardless of the toothbrush type. With both toothbrushes, subjects moved frequently between areas (MT 35 (14;79); PT 33 (14;85); n.s.) and brushed predominantly with circling and horizontal strokes; with the PT, 50.5% of the subjects spent only <10% of the brushing duration with passive brushing (positioning the brush head on the teeth with ≤2 movements/s). CONCLUSIONS: Intra-individual motion patterns were similar with both MT and PT, and most subjects persisted in their habitual motion patterns regardless of the toothbrush type. CLINICAL RELEVANCE: The use of PT and MT may need intensive training and supervision from oral hygiene educators in order to help subjects taking full advantage from these devices.

Toothpastes and enamel erosion/abrasion - Impact of active ingredients and the particulate fraction.

OBJECTIVES: To investigate in vitro a range of differently characterised toothpastes with respect to their efficacy in an erosion/abrasion setting with special emphasis on the role of the particulate ingredients. METHODS: Human enamel samples were erosively demineralised with citric acid (2min, 6×/day; 0.5%, pH 2.5; 10 days) and immersed in slurries (2min, 2×/day) either without or with brushing (15s, load 200g). The toothpastes were eight NaF-toothpastes, three hydroxyapatite-toothpastes (one without and two with NaF), one fluoride-free chitosan-toothpaste and three Sn-toothpastes. Negative control was erosion only, positive control was SnF2 gel. Tissue loss was quantified profilometrically. RESULTS: The SnF2 gel was most effective (reduction of tissue loss of 79%). Most of the products reduced tissue loss significantly when applied as slurries (between 28 and 66%). Brushing increased tissue loss in almost all toothpastes, only 5 formulations (all Sn-toothpastes and 2 NaF-toothpastes) reduced tissue loss significantly when compared to negative control (between 33 and 59%). There was a non-linear association between abrasiveness and amount of particles in a formulation, the particle size had no impact. CONCLUSIONS: Toothpastes had a protecting effect when applied as slurries but to a much lesser degree when applied with brushing. The particulate fraction may be a determinant for toothpaste efficacy in erosion/abrasion settings. CLINICAL SIGNIFICANCE: Toothpastes are important carriers of active agents against erosion, but physical impacts through brushing modifies efficacy distinctly. Understanding the role of the particulate fraction in toothpastes may offer perspectives for designing effective formulations for patients with erosive lesions.

In vitro Efficacy of Experimental Chitosan-Containing Solutions as Anti-Erosive Agents in Enamel.

The present study evaluated the effect of chitosans with different viscosities, dissolved in an AmF/SnCl2 solution, against erosion or erosion/abrasion. A total of 192 specimens were assigned to 2 × 6 groups (n = 16 specimens each): negative control, 4 chitosan solutions (groups Ch50, Ch500, Ch1000, and Ch2000, with viscosity of 50, 500, 1,000, or 2,000 mPas, respectively, 0.5% chitosan, 500 ppm F-, 800 ppm Sn2+, pH 4.4), and positive control (500 ppm F-, 800 ppm Sn2+, pH 4.3). One half of the groups was demineralized (experiment 1, E1; 10 days, 6 × 2 min/day, 0.5% citric acid, pH 2.8) and exposed to solutions (2 × 2 min/day); the other half was additionally brushed (15 s, 200 g) with non-fluoridated toothpaste before solution immersion (experiment 2, E2). Treatment effects were investigated by profilometry, energy-dispersive X-ray spectroscopy and scanning electron microscopy (SEM). In E1, all the chitosan-containing solutions reduced enamel loss by 77-80%, to the same extent as the positive control, except for Ch2000 (p ≤ 0.05), which completely inhibited tissue loss by the formation of precipitates. In E2, Ch50 and Ch500 showed best performance, with approximately 60% reduction of tissue loss compared to the negative control group (p ≤ 0.05 compared to other groups). SEM analysis showed differences between negative control and the other groups but only minor differences amongst the groups treated with active agents. In both E1 and E2, treatment with active agents resulted in surface enrichment of carbon and tin compared to negative control (p ≤ 0.001); brushing removed parts of carbon and tin (p ≤ 0.001). Chitosan shows different properties under erosive and erosive/abrasive conditions. Under erosive conditions high viscosity might be helpful, whereas lower viscosity seems to be more effective in cases of chemo-mechanical challenges.

Consensus report of the European Federation of Conservative Dentistry: erosive tooth wear--diagnosis and management.

OBJECTIVE: Due to an increased focus on erosive tooth wear (ETW), the European Federation of Conservative Dentistry (EFCD) considered ETW as a relevant topic for generating this consensus report. MATERIALS AND METHODS: This report is based on a compilation of the scientific literature, an expert conference, and the approval by the General Assembly of EFCD. RESULTS: ETW is a chemical-mechanical process resulting in a cumulative loss of hard dental tissue not caused by bacteria, and it is characterized by loss of the natural surface morphology and contour of the teeth. A suitable index for classification of ETW is the basic erosive wear examination (BEWE). Regarding the etiology, patient-related factors include the pre-disposition to erosion, reflux, vomiting, drinking and eating habits, as well as medications and dietary supplements. Nutritional factors relate to the composition of foods and beverages, e.g., with low pH and high buffer capacity (major risk factors), and calcium concentration (major protective factor). Occupational factors are exposition of workers to acidic liquids or vapors. Preventive management of ETW aims at reducing or stopping the progression of the lesions. Restorative management aims at reducing symptoms of pain and dentine hypersensitivity, or to restore esthetic and function, but it should only be used in conjunction with preventive strategies. CONCLUSIONS: Effective management of ETW includes screening for early signs of ETW and evaluating all etiological factors. CLINICAL RELEVANCE: ETW is a clinical condition, which calls for the increased attention of the dental community and is a challenge for the cooperation with other medical specialities.

Toothbrushing and flossing behaviour in young adults--a video observation.

OBJECTIVES: Video observation studies of habitual oral hygiene from the 1970s revealed a striking neglect of brushing oral surfaces and unsystematic brushing patterns with frequent movements between areas. These findings were not systematically followed up; furthermore, nothing is known about whether subjects are able to floss sufficiently. Therefore, the aim of this video study was to analyse the performance of habitual toothbrushing and flossing. METHODS: A random sample of 101 18-year-olds was included. Toothbrush and floss were provided; habitual brushing/flossing was videotaped in a standardised setting and analysed with the video coding software INTERACT. Parameters of interest were toothbrushing duration, type of brushing strokes, brushing patterns, flossed interproximal spaces and flossing technique. RESULTS: The mean brushing duration was 156.0 ± 71.1 s; duration differed only slightly between the upper and lower jaw as well as between the right, left and anterior areas. However, oral surfaces were brushed distinctly shorter than vestibular surfaces (27.1 ± 27.8 s versus 72.1 ± 31.8 s; p ≤ 0.001). Participants brushed different areas of the mouth with different types of strokes, predominantly with horizontal and circular strokes. Brushing movements frequently alternated between areas (45.1 ± 22.4) not randomly but accumulated within a jaw with a tendency to move from the right to the left. Half of the participants flossed, but only one performed sufficiently. CONCLUSIONS: There was a significant neglect of brushing oral surfaces and insufficient use of floss. Brushing patterns were similar to those observed in the 1970s. CLINICAL RELEVANCE: Understanding habitual oral hygiene behaviour is essential for improving oral hygiene instruction strategies.

Erosion/abrasion-preventing potential of NaF and F/Sn/chitosan toothpastes in dentine and impact of the organic matrix.

The study investigated the erosion/abrasion-preventing potential of experimental NaF (1,400 ppm F(-)) and amine fluoride (AmF)/NaF/SnCl2/chitosan (1,400 ppm F(-), 3,500 ppm Sn(2+), 0.5% chitosan) toothpastes relative to placebo and SnF2 gel (970 ppm F(-), 3,000 ppm Sn(2+)), and the impact of the demineralised dentine matrix on toothpaste effects. The study was a cyclic erosion/intervention experiment (10 days). Samples were stored in mineral salt solution either without or with collagenase (from Clostridium histolyticum type VII; 100 U/ml) for continuous removal of the organic matrix. To produce a comparable order of tissue loss, erosion was performed 6 × 30 s/day with 0.5% citric acid in the latter and 6 × 90 s/day with 1% citric acid in the former. Intervention was toothpaste slurry immersion (2 × 2 min/day); half of the samples were additionally brushed for 15 s within this time (brushing machine, load 200 g). Tissue loss was determined profilometrically (mean ± SD; µm). Tissue loss values (without/with brushing) for placebo, NaF, AmF/NaF/SnCl2/chitosan and SnF2 gel, respectively, were 11.6 ± 3.1/12.2 ± 2.5, 12.7 ± 3.1/10.7 ± 4.5, 8.7 ± 2.1/9.7 ± 2.1 and 8.8 ± 1.8/​10.9 ± 1.8 in the presence of the organic matrix and 10.7 ± 3.2/11.9 ± 2.1, 8.2 ± 4.0/10.1 ± 4.1, 8.7 ± 2.9/9.1 ± 1.8 and 8.4 ± 1.9/7.5 ± 1.5 in the absence of the organic matrix. Relative to placebo, the NaF formulation had no significant effects; the AmF/NaF/SnCl2/chitosan formulation significantly reduced tissue loss between 20 and 25% except when applied without brushing in the absence of the organic matrix. The effects of the formulations were similar both in the presence and absence of the organic matrix. Sn(2+)/F(-)-​containing formulations have the potential to reduce erosion/abrasion even in the absence of demineralised collagen; seeking for more effective formulations is desirable.

Effect of a chitosan additive to a Sn2+-containing toothpaste on its anti-erosive/anti-abrasive efficacy--a controlled randomised in situ trial.

OBJECTIVES: It is well known that Sn(2+) is a notable anti-erosive agent. There are indications that biopolymers such as chitosan can enhance the effect of Sn(2+), at least in vitro. However, little information exists about their anti-erosive/anti-abrasive in situ effects. In the present in situ study, the efficacy of Sn(2+)-containing toothpastes in the presence or absence of chitosan was tested. METHODS: Ten subjects participated in the randomised crossover study, wearing mandibular appliances with human enamel specimens. Specimens were extraorally demineralised (7 days, 0.5% citric acid, pH 2.6; 6 × 2 min/day) and intraorally exposed to toothpaste suspensions (2 × 2 min/day). Within the suspension immersion time, one half of the specimens were additionally brushed intraorally with a powered toothbrush (5 s, 2.5 N). Tested preparations were a placebo toothpaste (negative control), two experimental toothpastes (F/Sn = 1,400 ppm F(-), 3,500 ppm Sn(2+); F/Sn/chitosan = 1,400 ppm F(-), 3,500 ppm Sn(2+), 0.5 % chitosan) and an SnF2-containing gel (positive control, GelKam = 3,000 ppm Sn(2+), 1,000 ppm F(-)). Substance loss was quantified profilometrically (µm). RESULTS: In the placebo group, tissue loss was 11.2 ± 4.6 (immersion in suspension) and 17.7 ± 4.7 (immersion in suspension + brushing). Immersion in each Sn(2+)-containing suspension significantly reduced tissue loss (p ≤ 0.01); after immersion in suspension + brushing, only the treatments with GelKam (5.4 ± 5.5) and with F/Sn/chitosan (9.6 ± 5.6) significantly reduced loss [both p ≤ 0.05 compared to placebo; F/Sn 12.8 ± 6.4 (not significant)] CONCLUSION: Chitosan enhanced the efficacy of the Sn(2+)-containing toothpaste as an anti-erosive/anti-abrasive agent. CLINICAL RELEVANCE: The use of Sn(2+)- and chitosan-containing toothpaste is a good option for symptomatic therapy in patients with regular acid impacts.

Randomised in situ study on the efficacy of a tin/chitosan toothpaste on erosive-abrasive enamel loss.

Tin is a notable anti-erosive agent, and the biopolymer chitosan has also shown demineralisation-inhibiting properties. Therefore, the anti-erosive/anti-abrasive efficacy of the combination of both compounds was tested under in situ conditions. Twenty-seven volunteers were included in a randomised, double-blind, three-cell crossover in situ trial. Enamel specimens were recessed on the buccal aspects of mandibular appliances, extraorally demineralised (6 × 2 min/day) and intraorally treated with toothpaste slurries (2 × 2 min/day). Within the slurry treatment time, one-half of the specimens received additional intraoral brushing (5 s, 2.5 N). The tested toothpastes included a placebo toothpaste, an experimental NaF toothpaste (1,400 ppm F(-)) and an experimental F/Sn/chitosan toothpaste (1,400 ppm F(-), 3,500 ppm Sn(2+), 0.5% chitosan). The percentage reduction of tissue loss (slurry exposure/slurry exposure + brushing) compared to placebo was 19.0 ± 47.3/21.3 ± 22.4 after use of NaF and 52.5 ± 30.9/50.2 ± 34.3 after use of F/Sn/chitosan. F/Sn/chitosan was significantly more effective than NaF (p ≤ 0.001) and showed good efficacy against erosive and erosive-abrasive tissue loss. This study suggests that the F/Sn/chitosan toothpaste could provide good protection for patients who frequently consume acidic foodstuffs.

Efficacy of a moisture-tolerant material for fissure sealing: a prospective randomised clinical trial.

OBJECTIVES: Fissure sealings offer nearly complete protection against fissure caries, provided that they are adequately applied, for composite-based sealants with sufficient moisture control. This is not always attainable, particularly in children with low compliance. To counter this problem, a moisture-tolerant sealant has been developed. The present randomised clinical trial compared such a moisture-tolerant material (Embrace) with a conventional sealant (Helioseal). MATERIAL AND METHODS: In 55 participants (mean age, 10 ± 3 years), corresponding molar pairs were sealed with either Embrace or Helioseal. Retention, quality of sealing, and caries were clinically examined, both tactilely and visually, immediately and after 1 year. RESULTS: After 1 year, 93% of Helioseal sealings were complete, whereas 60% of Embrace sealings showed partial and 13% complete loss. The surface quality of Embrace was significantly worse than that of Helioseal. After the use of Embrace, the sealant margin was noticeable as a slight (distinct) step in 36% (15%). The visual (tactile) examination showed a rough surface in 78% (33%) in the case of Embrace. The Helioseal surfaces were shiny (smooth) in all cases (all differences between Helioseal and Embrace, p ≤ 0.001). Caries was found only after the use of Embrace (4%, n.s. compared to Helioseal). CONCLUSION: The moisture-tolerant material Embrace was distinctly inferior to Helioseal because Embrace showed weaknesses in retention and surface quality. CLINICAL RELEVANCE: Even if a moisture-tolerant sealant would be desirable in particular for children with low compliance, the tested material does not represent an alternative to the standard preparation.

Relationship between plaque score and video-monitored brushing performance after repeated instruction--a controlled, randomised clinical trial.

OBJECTIVES: Aim of this prospective, randomised, controlled clinical trial was to use the modified bass technique (MBT) and a specific brushing sequence to investigate whether two types of instruction methods lead to differences in plaque reduction and whether plaque reduction is related to technique adoption. METHODS: Ninety-eight participants were randomly assigned to three groups: (1) control, no instruction; (2) verbal instruction by means of a leaflet; and (3) verbal instruction supported by demonstration, no leaflet. Brushing performance was video monitored. Plaque score (Turesky modified QHI (T-QHI)) was measured at baseline, afterwards participants received instructions. After 2 weeks, T-QHI was measured for a second time, and participants were re-instructed. After another 2 weeks, T-QHI was measured for a third time. RESULTS: At baseline, T-QHI did not differ between groups ((1) 1.99 ± 0.51, (2) 1.90 ± 0.51, (3) 1.93 ± 0.56). The second measurement revealed an improvement of T-QHI in the instructed groups and in the non-instructed control group ((1) 1.80 ± 0.47, (2) 1.58 ± 0.58, (3) 1.64 ± 0.58; n.s. between groups); in the intervention groups, remotivation achieved no further improvement ((1) 1.72 ± 0.48, (2) 1.52 ± 0.58, (3) 1.50 ± 0.69; n.s. between groups and compared to second measurement). Improvement of T-QHI was not related to proper performance of technique or brushing sequence. Those who fully adopted the brushing technique, the sequence or both did not have lower plaque scores. CONCLUSION: Technical performance and effectiveness were not linked. CLINICAL RELEVANCE: Within the study setting, the MBT was not effective in reducing plaque scores. The general recommendation of the MBT should be re-evaluated in further studies.

Is dental erosion really a problem?

Dental erosion is the non-carious dental substance loss induced by direct impact of exogenous or endogenous acids. It results in a loss of dental hard tissue, which can be serious in some groups, such as those with eating disorders, in patients with gastroesophageal reflux disease, and also in persons consuming high amounts of acidic drinks and foodstuffs. For these persons, erosion can impair their well-being, due to changes in appearance and/or loss of function of the teeth, e.g., the occurrence of hypersensitivity of teeth if the dentin is exposed. If erosion reaches an advanced stage, time- and money-consuming therapies may be necessary. The therapy, in turn, poses a challenge for the dentist, particularly if the defects are diagnosed at an advanced stage. While initial and moderate defects can mostly be treated non- or minimally invasively, severe defects often require complex therapeutic strategies, which often entail extensive loss of dental hard tissue due to preparatory measures. A major goal should therefore be to diagnose dental erosion at an early stage, to avoid functional and esthetic impairments as well as pain sensations and to ensure longevity of the dentition.

Efficacy of the stannous ion and a biopolymer in toothpastes on enamel erosion/abrasion.

OBJECTIVES: Sn(2+) has promising erosion-inhibiting properties in solutions, but little is known about respective effects in toothpastes. In addition, biopolymers might have protecting potential. Aim of this study was to investigate the effects of Sn(2+) in toothpastes and of a biopolymer (chitosan) added to a Sn(2+) formulation on erosion/abrasion. METHODS: Enamel samples were subjected to cyclic erosion procedures (10 days; 0.50% citric acid, pH 2.5; 6× 2 min/day), and brushing (2× 15s/day, load 200 g) during immersion in slurries (2 min). The toothpastes were NaF formulations (NaF/1, NaF/2, NaF/3) and Sn(2+) formulations (NaF/SnCl(2), AmF/SnF(2), AmF/NaF/SnCl(2)) and AmF/NaF/SnCl(2)+0.5% chitosan. Declared concentrations of active ingredients in toothpastes were 1400-1450 µg/g F(-) and 3280-3500 µg/g Sn(2+). Negative controls were erosion only and placebo, positive control was a SnF(2) gel. Tissue loss was quantified profilometrically, Sn on enamel surfaces was measured by energy dispersive X-ray spectroscopy. RESULTS: Loss values (µm) for erosion only and placebo were 14.4 ± 4.5 and 20.2 ± 3.8, respectively, and 4.6 ± 1.9 for the positive control (p ≤ 0.001 each compared to erosion only). The other loss values were: NaF/1 16.5 ± 3.0, NaF/2 14.0 ± 2.7, NaF/3 12.6 ± 3.9, NaF/SnCl(2) 14.7 ± 5.1, AmF/SnF(2) 13.5 ± 4.8, AmF/NaF/SnCl(2) 12.4 ± 4.2, AmF/NaF/SnCl(2)+chitosan 6.6 ± 3.5 (except NaF/1 all p ≤ 0.01 compared to placebo). AmF/NaF/SnCl(2)/chitosan was more effective than all other toothpastes (p ≤ 0.01 each). Sn on the enamel surface ranged between 1.3 ± 0.3 and 2.8 ± 0.04 wt.% with no obvious relationship with efficacy. CONCLUSIONS: The NaF and Sn(2+) toothpastes without chitosan exhibited similar anti-erosion and abrasion-prevention effects. The experimental Sn(2+) formulation with chitosan revealed promising results similar to those of the positive control. CLINICAL SIGNIFICANCE: NaF toothpastes offer a degree of protection against erosion/abrasion, which is likely sufficient for most subjects with average acid exposures. For patients with initial erosive lesions, however, more effective toothpaste is desirable. The combination of Sn(2+) and a biopolymer appears promising in this context.

Enzyme activities in the oral fluids of patients suffering from bulimia: a controlled clinical trial.

Patients with bulimia nervosa are at high risk for dental erosion. However, not all bulimic patients suffer from erosion, irrespective of the severity of their eating disorder. It is often speculated that differences in the saliva are important, however, little is known about salivary parameters in bulimic patients, particularly directly after vomiting. The aim of the clinical trial was to compare different salivary parameters of subjects suffering from bulimia with those of healthy controls. Twenty-eight subjects participated (14 patients with bulimia nervosa, 7 of them with erosion; 14 matched healthy controls). Resting and stimulated saliva of all participants was analysed as well as saliva collected from bulimic patients directly and 30 min after vomiting. Parameters under investigation were flow rate, pH, buffering capacity and the enzyme activities of proteases in general, collagenase, pepsin, trypsin, amylase, peroxidase, and lysozyme. Regarding flow rate, pH and buffering capacity only small differences were found between groups; buffering capacity directly after vomiting was significantly lower in bulimic subjects with erosion than in subjects without erosion. Differences in enzymatic activities were more pronounced. Activities of proteases, collagenase and pepsin in resting and proteases in stimulated saliva were significantly higher in bulimic participants with erosion than in controls. Peroxidase activity was significantly decreased by regular vomiting. Proteolytic enzymes seem to be relevant for the initiation and progression of dental erosion directly after vomiting, maybe by both hydrolysis of demineralized dentine structures as well as modulation of the pellicle layer.

Conventional and anti-erosion fluoride toothpastes: effect on enamel erosion and erosion-abrasion.

New toothpastes with anti-erosion claims are marketed, but little is known about their effectiveness. This study investigates these products in comparison with various conventional NaF toothpastes and tin-containing products with respect to their erosion protection/abrasion prevention properties. In experiment 1, samples were demineralised (10 days, 6 × 2 min/day; citric acid, pH 2.4), exposed to toothpaste slurries (2 × 2 min/day) and intermittently stored in a mineral salt solution. In experiment 2, samples were additionally brushed for 15 s during the slurry immersion time. Study products were 8 conventional NaF toothpastes (1,400-1,490 ppm F), 4 formulations with anti-erosion claims (2 F toothpastes: NaF + KNO(3) and NaF + hydroxyapatite; and 2 F-free toothpastes: zinc-carbonate-hydroxyapatite, and chitosan) and 2 Sn-containing products (toothpaste: 3,436 ppm Sn, 1,450 ppm F as SnF(2)/NaF; gel: 970 ppm F, 3,030 ppm Sn as SnF(2)). A mouth rinse (500 ppm F as AmF/NaF, 800 ppm Sn as SnCl(2)) was the positive control. Tissue loss was quantified profilometrically. In experiment 1, most NaF toothpastes and 1 F-free formulation reduced tissue loss significantly (between 19 and 42%); the Sn-containing formulations were the most effective (toothpaste and gel 55 and 78% reduction, respectively). In experiment 2, only 4 NaF toothpastes revealed significant effects compared to the F-free control (reduction between 29 and 37%); the F-free special preparations and the Sn toothpaste had no significant effect. The Sn gel (reduction 75%) revealed the best result. Conventional NaF toothpastes reduced the erosive tissue loss, but had limited efficacy regarding the prevention of brushing abrasion. The special formulations were not superior, or were even less effective.

Dental erosion--an overview with emphasis on chemical and histopathological aspects.

The quality of dental care and modern achievements in dental science depend strongly on understanding the properties of teeth and the basic principles and mechanisms involved in their interaction with surrounding media. Erosion is a disorder to which such properties as structural features of tooth, physiological properties of saliva, and extrinsic and intrinsic acidic sources and habits contribute, and all must be carefully considered. The degree of saturation in the surrounding solution, which is determined by pH and calcium and phosphate concentrations, is the driving force for dissolution of dental hard tissue. In relation to caries, with the calcium and phosphate concentrations in plaque fluid, the 'critical pH' below which enamel dissolves is about 5.5. For erosion, the critical pH is lower in products (e.g. yoghurt) containing more calcium and phosphate than plaque fluid and higher when the concentrations are lower. Dental erosion starts by initial softening of the enamel surface followed by loss of volume with a softened layer persisting at the surface of the remaining tissue. Dentine erosion is not clearly understood, so further in vivo studies, including histopathological aspects, are needed. Clinical reports show that exposure to acids combined with an insufficient salivary flow rate results in enhanced dissolution. The effects of these and other interactions result in a permanent ion/substance exchange and reorganisation within the tooth material or at its interface, thus altering its strength and structure. The rate and severity of erosion are determined by the susceptibility of the dental tissues towards dissolution. Because enamel contains less soluble mineral than dentine, it tends to erode more slowly. The chemical mechanisms of erosion are also summarised in this review. Special attention is given to the microscopic and macroscopic histopathology of erosion.