Influence of the Relative Enamel Abrasivity (REA) of Toothpastes on the Uptake of KOH-soluble and Structurally Bound Fluoride.

PURPOSE: To determine the influence of the relative enamel abrasivity (REA) of fluoridated toothpaste on the uptake of KOH-soluble and structurally bound fluoride into enamel. MATERIALS AND METHODS: Bovine enamel samples were randomly allocated to 6 groups (n=36 per group). Groups A to C were treated with sodium fluoride (NaF) toothpastes and groups D to F with amine fluoride (AmF) toothpastes (1500 ppm F each). The REA in groups A and D was 2, in groups B and E it was 6 and in groups C and F it was 9. Twice a day, 18 samples of each group were immersed for 2 min in a slurry (toothpaste:artificial saliva=1:3), while the remaining samples were brushed with the respective slurry (2.5 N force; 60 strokes/min; 2 min). All samples were stored at 37°C and 100% humidity. After five days, the amount of KOH-soluble and structurally bound fluoride was determined and statistically compared by Scheffe's post-hoc tests. RESULTS: REA value and mode of application (immersion or brushing) had no significant influence on the amount of either kind of fluoride from NaF toothpastes. Only for the NaF toothpaste with REA 6 was the amount of KOH-soluble fluoride significantly higher after brushing. With AmF toothpastes, KOH-soluble and structurally bound fluoride concentrations were significantly higher when the samples were brushed. Furthermore, in the REA-2 group, the amounts of KOH-soluble fluoride (brushed or immersed) and structurally bound fluoride (brushed) were significantly higher than in the other groups. CONCLUSION: The REA dependency of KOH-soluble and structurally bound fluoride was found only for the AmF toothpastes. Using AmF toothpaste, the mode of application influenced the uptake of KOH-soluble and structurally bound fluoride into enamel.

Effect of direct current on surface structure and cytocompatibility of titanium dental implants.

PURPOSE: A low direct current can be used to disinfect dental titanium implants in simulated physiologic environments. The aim of this study was to determine whether this treatment affects implant surface structure and cytocompatibility. MATERIALS AND METHODS: Titanium test disks with a sandblasted, acid-etched, large-grit (SLA) surface were placed as anodes in an electrolytic bath with physiologic saline and treated with 15 mA of current for 15 minutes. Surfaces were analyzed by light and electron microscopy and contact angle measurement. Depth profile analyses of SLA disks were run at subsurface levels from 0 to 1,000 nm. The proliferation and viability of preosteoblastic cells and human foreskin fibroblasts on implant surfaces were assessed. Alkaline phosphatase (ALP) activity was determined with and without exposure to bone morphogenetic protein-2 (BMP-2). Mineralization was determined after 4 weeks. RESULTS: A blue discoloration was observed after treating the SLA disks, but no damage was recognized microscopically. An oxidation layer formed on the surface and the wettability of the disks increased significantly. Cell proliferation and initial maturation were not affected by the treatment. Mineralization and ALP activity of BMP-exposed cells, however, were slightly but significantly reduced on test disks. CONCLUSIONS: The current study showed that the alterations in implant color after electrochemical treatment did not reflect significant surface changes, which would preclude cell adhesion and growth or have a major impact on osteoblastic differentiation or maturation.

Povidone-iodine gel and solution as adjunct to ultrasonic debridement in nonsurgical periodontitis treatment: an RCT pilot study.

OBJECTIVES: Polyvinylpyrrolidone-iodine (PVP-iodine or povidone- iodine) enhances the treatment outcomes of initial periodontal treatment but the degree of benefit varies in the literature. A main reason might be the concentration of the dosage form and its contact time with the periodontal tissues. In this randomized pilot study the effect of repeated subgingival application of PVP-iodine during scaling and root planing (SRP) was assessed. Changes of clinical parameters and microbiotic taxa after 3 months were analyzed. METHOD AND MATERIALS: In a split-mouth design 12 patients with generalized, severe periodontitis were treated with SRP combined with subgingival application of either PVP-iodine or water. Test and control sides were isolated with a special rubber dam technique. Irrigations were reapplied during SRP. Periodontal probing depth (PD) and recessions were documented before treatment and after 3 months. Samples of subgingival bacteria before SRP and after 1 week, 1 month, and 3 months were analyzed. RESULTS: Three months after SRP, changes for PD and recession in deep pockets were significantly higher in the PVP-iodine group (P = .012 and .044 respectively). The number of these pockets was reduced from 73 at baseline to 8 in the test and 19 in the control group. In both groups, bacterial taxa were reduced after 1 week. One month after SRP only taxa of Porphyromonas gingivalis in the PVP-iodine group were lower than at baseline. After 3 months, all taxa regained baseline values. CONCLUSION: PVP-iodine reapplied frequently during SRP might enhance pocket depth reduction in initially deep pockets.

Effect of low direct current on anaerobic multispecies biofilm adhering to a titanium implant surface.

PURPOSE: Peri-implantitis is caused by biofilm adhering to the implant. It has been shown that bactericidal electrolysis products are generated when a low direct current is applied to a titanium implant used as the anode. The hypothesis of this study was that low-current electrolysis would eradicate viable bacteria in a simulated subgingival multispecies biofilm adhering to a titanium implant surface. MATERIAL AND METHODS: Biofilms consisting of eight anaerobic species were grown on pellicle-coated titanium discs with sand-blasted, acid-etched, large-grit (SLA; Straumann, Basel, Switzerland) surface. After 40.5 hours of growth, discs were treated with 10 mA for 10 minutes in an electrolytical setup with physiological saline and gelatin. RESULTS: Low direct current at discs used as the cathode caused a reduction of three to four orders of magnitude in viable counts, while no viable bacteria were recovered from anode discs (Mann-Whitney U-test, p < .01). Confocal laser scanning microscopy in combination with a live/dead stain showed biofilm detachment at the cathode and reduced viability at the anode. CONCLUSION: Electrochemical treatment of diseased implants appears to be promising and well worth investigating further.

The prevalence of approximal caries in patients after fixed orthodontic treatment and in untreated subjects: a retrospective, cross-sectional study on bitewing radiographs.

OBJECTIVE: The aim of this retrospective, cross-sectional study was to investigate the prevalence of approximal carious lesions in patients after fixed multibracket therapy and in subjects without orthodontics on bitewing radiographs. MATERIAL AND METHODS: Bitewing radiographs of 104 orthodontically treated patients with fixed multibracket appliances were compared to those of 111 untreated subjects. The individuals in both groups were between 15 and 16.25 years of age when radiographs were taken. The test group with orthodontics was recruited from the archive of the Department of Orthodontics at the University of Zürich. The untreated control group was selected randomly from 16 communities in the Canton of Zürich. The approximal surfaces of the permanent premolars and molars of all subjects were assessed by two calibrated investigators. RESULTS: The average number of enamel lesions in the test group after fixed orthodontic treatment was lower than in the control group (0.57 vs. 1.85, p < 0.001). The same was found for dentin lesions (0.06 vs. 0.49, p < 0.001). The distribution of lesions was similar in both groups. CONCLUSION: Fewer approximal carious lesions were detected in the test group after fixed multibracket appliances than in the age-matched control group without orthodontic treatment.

Peri-implantitis prevalence and treatment in implant-oriented private practices: a cross-sectional postal and Internet survey.

This survey aimed to estimate the subjective prevalence of peri-implantitis and its management in the private with and without board certified specialization. For this purpose, a cross-sectional postal and internet survey of 521 dentists, representing all members of the Swiss Society of Oral Implantology (SGI) was conducted (year 2010). The questionnaire consisted of four sections assessing 1) general information regarding the practice setting and education, 2) general questions regarding implantation profile and 3) specific questions regarding the prevalence and experience with the management of peri-implantitis. In the fourth section, therapy options of three exemplary cases were assessed. The data were separately evaluated and compared for specialists (S) and n₋specialists (N-S). A total of 253 questionnaires could be included in the present study. The results revealed that specialists placed significantly more implants than non-specialists. The subjective prevalence of cases with peri₋implantitis was 5-6 and 7-9% after 5 and 10 years, respectively. The polled dentists perceived periodontitis (N-S: 72%; S: 80%), smoking (N-S: 71; S: 77%) and bad compliance (S: 53; N-S: 61%) as the most important risk factors for peri-implantitis. Chlorhexidine was the most frequently used antiseptic agent for disinfection. A surgical approach to treat peri-implantitis was reported by more than 80% of all dentists. Specialists used significantly more resective or regenerative approaches than non-specialists.

Coupling plowing of cartilage explants with gene expression in models for synovial joints.

Articular cartilage undergoes complex loading modalities generally including sliding, rolling and plowing (i.e. the compression by a condyle normally to the tissue surface under simultaneously tangential displacement, thus generating a tractional force due to tissue deformation). Although in in vivo studies it was shown that excessive plowing can lead to osteoarthritis, little quantitative experimental work on this loading modality and its mechanobiological effects is available in the literature. Therefore, a rolling/plowing explant test system has been developed to study the effect on pristine cartilage of plowing at different perpendicular forces. Cartilage strips harvested from bovine nasal septa of 12-months-old calves were subjected for 2h to a plowing-regime with indenter normal force of 50 or 100 N and a sliding speed of 10 mm s(-1). 50 N produced a tractional force of 1.2±0.3N, whereas 100 N generated a tractional force of 8.0±1.4N. Furthermore, quantitative-real-time polymerase chain reaction experiments showed that TIMP-1 was 2.5x up-regulated after 50 N plowing and 2x after 100 N plowing, indicating an ongoing remodeling process. The expression of collagen type-I was not affected after 50 N plowing but it was up-regulated (6.6x) after 100 N plowing, suggesting a possible progression to an injury stage of the cartilage, as previously reported in cartilage of osteoarthritic patients. We conclude that plowing as performed by our mimetic system at the chosen experimental parameters induces changes in gene expression depending on the tractional force, which, in turn, relates to the applied normal force.

Caries risks and appropriate intervals between bitewing x-ray examinations in schoolchildren.

Short intervals between bitewing examinations favor the timely detection of lesions on approximal surfaces. Long intervals reduce the exposure to radiation. Thus, the question arises which intervals between bite-wing examinations are appropriate. The length of intervals between bitewing examinations should be adapted to the caries risk on approximal surfaces of molars and premolars. In order to estimate the caries risk in the Swiss school population, longitudinal data of 591 schoolchildren from the Canton (County) of Zurich were analyzed. These schoolchildren had been examined at 4-year intervals. The proportion of 7-year-olds with caries increment on approximal surfaces within 4 years was 7.1%, i.e., the caries risk in the population was 7.1%. In the 11-year-olds, the caries risk was 17.60%. Seven-year-olds without caries experience on selected approximal surfaces had a low caries risk of 2.2%. However, 7-year-olds with caries experience on selected approximal surfaces had a high risk of 24.2%. The same applied to 11-year-olds: those without caries experience had a low risk (7.5%), and those with caries experience had a high risk (38.5%). For the 7-year-old schoolchildren without any caries experience, an x-ray interval of 8 years is proposed. For the 7-year-old schoolchildren with caries experience, an x-ray interval of 1 year is proposed.

Electrochemical disinfection of dental implants--a proof of concept.

BACKGROUND: Peri-implantitis has gained significant clinical attention in recent years. This disease is an inflammatory reaction to microorganisms around dental implants. Due to the limited accessibility, non-invasive antimicrobial strategies are of high interest. An unexpected approach to implant disinfection may evolve from electrolysis. Given the electrical conductivity of titanium implants, alkalinity or active oxidants can be generated in body fluids. We investigated the use of dental titanium implants as electrodes for the local generation of disinfectants. Our hypothesis was that electrolysis can reduce viable counts of adhering bacteria, and that this reduction should be greater if active oxidative species are generated. METHODOLOGY/PRINCIPAL FINDINGS: As model systems, dental implants, covered with a mono-species biofilm of Escherichia coli C43, were placed in photographic gelatin prepared with physiological saline. Implants were treated by a continuous current of 0-10 mA for 15 minutes. The reduction of viable counts was investigated on cathodes and anodes. In separate experiments, the local change in pH was visualized using color indicators embedded in the gelatin. Oxidative species were qualitatively detected by potassium iodide-starch paper. The in situ generated alkaline environment around cathodic implants caused a reduction of up to 2 orders of magnitude in viable E. coli counts. On anodic implants, in contrast to cathodic counterparts, oxidative species were detected. Here, a current of merely 7.5 mA caused complete kill of the bacteria. CONCLUSIONS/SIGNIFICANCE: This laboratory study shows that electrochemical treatment may provide access to a new way to decontaminate dental implants in situ.

Further caries decline in Swiss recruits from 1996 to 2006.

Previous investigations showed a steady decline of the caries experience. The purpose of this study was to determine the caries experience of Swiss recruits in 2006 and to compare it to that of 1985 and 1996. The results of a parallel investigation which dealt with the periodontal health of the same recruits have already been published (Röthlisberger et al. 2007). Investigations on recruits in 1970 (Curilovic et al. 1972) and 1974 (Curilovic et al. 1980) used another methodology. Therefore, they were not included here for comparison.

In vitro tooth cleaning efficacy of electric toothbrushes around brackets.

This in vitro study assessed the cleaning efficacy of different electric toothbrushes around upper incisor brackets. Standard and Mini Diamond brackets were fixed on black-stained teeth. The teeth were coated with white titanium oxide and brushed in a machine twice for 1 minute each. Twelve different brush heads with either a wiping or an oscillating-rotating action were tested. After brushing, the teeth were scanned, the black surfaces were assessed planimetrically and a modified plaque index for orthodontic patients (PIOP) was introduced. Tooth areas, which were black again after brushing indicated tooth surface contact of the filaments and were expressed as a percentage of total area. The remaining white areas around the brackets indicated 'plaque-retentive' niches. Analysis of variance was used for individual comparison of the brush types. Bonferroni/Dunn adjustment was applied for multiple testing. The Sonicare toothbrush handle with the brush head 'Compact ProResults' (81.7 per cent) and the brush head 'Standard ProResults' (80.8 per cent), as well as the sonic Waterpik toothbrush SR 800E with the standard brush head (78.2 per cent), showed statistically significantly better cleaning efficacy than all others. The poorest cleaning efficacy was observed for the oscillating-rotating Braun Oral-B Professional Care with the brush head 'Ortho' (less than 50 per cent). The planimetric findings were in correspondence with the results of the PIOP assessment. Cleaning efficacy of electric toothbrushes around brackets on upper incisors was different between the tested brushes. The PIOP was practicable, effective, and easy to use, although it has to be verified in a clinical study.

Assessment of dental fluorosis prevalence in Swiss populations.

In 1996 and 2006, recruits of the Swiss army participated in a dental survey. Similarly in 1995/96 and 2004/05, randomly selected schoolchildren from 16 rural communities of the Canton of Zurich participated in a dental survey. As part of these surveys, color slides were taken of the incisor teeth of all recruits, as well as of third and fourth grade schoolchildren. The slides (N = 2049) were examined for the presence of fluoride-associated enamel opacities (FOP), using the Thyl-strup-Fejerskov (TF) index. Two examiners (A and B) assessed all slides. The examiners were blind as to the year of survey. Examiner A recorded prevalences of FOP between 18% and 27% depending on population; examiner B recorded prevalences between 7% and 12%. The examiners' influence on the estimation of the prevalence was obvious. The prevalences reported should, therefore, be considered as rough estimates. FOP of TF score 2 were only observed in approximately 1% of the participants. One examiner recorded a TF score 3 in a single individual. FOP therefore are not a cosmetic problem and certainly not a public health concern. The prevalence of FOP decreased slightly during observation period I (recruits born 1975-77 vs 1985-87) and period II (school children born 1985-87 vs 1994-96). However, the decline was statistically supported in only one instance (Period I, Examiner B).

Changes in dental caries in Zurich school-children over a period of 45 years.

In 16 rural communities of the Canton of Zurich, school-children of all age groups participated in dental examinations conducted at intervals of 4 years since 1963/64. The same standardised method was used throughout the entire period. This study documents the caries experience over a period of 45 years. From 1964 to 2009, the DM*FT per 14-year-old child fell from 12.50 to 1.31, corresponding to a caries reduction of 90%. The caries experience in 8-, 10- and 12-year-olds decreased by 90% to 92%. From 1964 to 2009, the "Significant Caries Index" (the mean DM*FT in the third of 12-year-olds with the highest DM*FT values) fell from 13.09 to 2.20, corresponding to a caries reduction of 83%. The observed caries decline was unexpectedly high. The effect of fluorides may explain a caries reduction of roughly 50%. A large part of the decline, however, remains unexplained. Possible causes are discussed in this paper.

The impact of the stone age diet on gingival conditions in the absence of oral hygiene.

BACKGROUND: The objective of this study was to assess the oral microbiota and clinical data in subjects without access to traditional oral hygiene methods and who ate a diet available in the Stone Age. METHODS: Ten subjects living in an environment replicating the Stone Age for 4 weeks were enrolled in this study. Bleeding on probing (BOP), gingival and plaque indices, and probing depth (PD) were assessed at baseline and at 4 weeks. Microbiologic samples were collected at the mesio-buccal subgingival aspects of all teeth and from the dorsum of the tongue and were processed by checkerboard DNA-DNA hybridization methods. RESULTS: No subject had periodontitis. Mean BOP decreased from 34.8% to 12.6% (P <0.001). Mean gingival index scores changed from 0.38 to 0.43 (not statistically significant) and mean plaque scores increased from 0.68 to 1.47 (P <0.001). PD at sites of subgingival sampling decreased (mean difference: 0.2 mm; P <0.001). At week 4, the total bacterial count was higher (P <0.001) for 24 of 74 species, including Bacteroides ureolyticus, Eikenella corrodens, Lactobacillus acidophilus, Capnocytophaga ochracea, Escherichia coli, Fusobacterium nucleatum naviforme, Haemophilus influenzae, Helicobacter pylori, Porphyromonas endodontalis, Staphylococcus aureus (two strains), Streptococcus agalactiae, Streptococcus anginosis, and Streptococcus mitis. Bacterial counts from tongue samples were higher at baseline (P <0.001) for 20 species, including Tannerella forsythia (previously T. forsythensis), Aggregatibacter actinomycetemcomitans (previously Actinobacillus actinomycetemcomitans; serotype a), and Streptococcus spp. CONCLUSIONS: The experimental gingivitis protocol is not applicable if the diet (e.g., Stone Age) does not include refined sugars. Although plaque levels increased, BOP and PD decreased. Subgingival bacterial counts increased for several species not linked to periodontitis, whereas tongue bacterial samples decreased during the study period.

Cannabis and caries--does regular cannabis use increase the risk of caries in cigarette smokers?

The use of cannabis by adolescents in Switzerland has almost doubled in the past decade. Empirical observations in private dental practices indicate that cannabis users have more carious lesions than those who do not use cannabis. The aim of this study was to investigate the hypothesis that regular cannabis use increases the risk of caries because of hyposalivation or lifestyle. Forty-three regular cannabis users were enrolled in the test group and 42 tobacco smokers were used as a negative control group. All subjects were 18-25 years old. Data were obtained using a standardized questionnaire and a clinical examination. There was no significant difference between groups in decayed and filled surfaces (DFS), saliva flow rate and plaque and gingival indices. The cannabis group had, however, significantly higher DS (decayed surface) values (p = 0.0001) and significantly lower frequencies of daily tooth brushing and dental control visits (p < 0.0001) than the control group. Additionally, the cannabis group reported a significantly higher consumption of sugar-containing beverages than the control group (p = 0.0078). To obtain more objective data relations, the DS values of male cannabis users were also compared with those of Swiss military recruits found in another study. The cannabis users had more caries on smooth surfaces than the military recruits. Although comparison with epidemiological data suggested that the prevalence of caries on smooth surfaces is elevated in cannabis users, DFS data indicated that cannabis users do not have an increased risk of caries. Lifestyle combined with short-term hyposalivation after delta-9-tetrahydrocannabinol consumption is the most probable cause of the high prevalence of caries on smooth surfaces in cannabis users. Further studies are needed to investigate the effects of cannabis use on oral health.

In vitro tooth cleaning efficacy of manual toothbrushes around brackets.

The purpose of this laboratory study was to assess the potential cleaning efficacy of nine different toothbrushes around brackets in vitro. Standard and Mini Diamond brackets were fixed on coloured teeth in a special model, coated with white titanium oxide, brushed in a machine with different manual toothbrushes (three different types: planar, staged, and v-shaped bristle field), and tested with a horizontal motion for 1 minute. After brushing, the teeth were scanned and the black surfaces were planimetrically assessed using a grey scale. Tooth areas which were black again after brushing indicated tooth surface contact of the filaments. The remaining white tooth areas around the brackets indicated 'plaque-retentive' niches. Statistical analysis was carried out using the Kruskal-Wallis one-way test of variance for individual comparison. Bonferroni adjustment was used for multiple testing, and comparison of bracket size with Wilcoxon signed rank test. In the most critical area of 2 mm around the brackets, there was no statistically significant difference between the different toothbrushes evaluated. The untouched area ranged from 11 to 26 per cent of the initially whitened tooth surface. By pooling the toothbrushes according to their design, the median cleaning efficacy of the v-shaped (73.1 per cent) and staged (75.6 per cent) toothbrushes resulted in significantly superior cleaning efficacy than planar toothbrushes (60.7 per cent) for standard brackets. For mini bracket type, staged toothbrushes showed a significantly better mean cleaning efficacy (77.8 per cent) than planar (65 per cent) and v-shaped (72.4 per cent) toothbrushes. Staged and v-shaped brush designs resulted in superior cleaning efficacy of teeth with fixed orthodontic attachments than toothbrushes with a planar bristle field. None of the tested toothbrushes showed a consistent, significantly higher cleaning efficacy than the others in this in vitro experiment.

Impact of toothpaste slurry abrasivity and toothbrush filament stiffness on abrasion of eroded enamel - an in vitro study.

OBJECTIVE: Toothbrush abrasion is significant in the development of tooth wear, particularly when combined with erosion. This in vitro study aimed to evaluate the impact of toothpaste slurry abrasivity and toothbrush filament stiffness on abrasion of eroded enamel. MATERIAL AND METHODS: Eroded enamel samples (hydrochloric acid, pH: 2.6, 15 s) were brushed with 40 strokes in an automatic brushing machine using manual toothbrushes with different filament stiffness (filament diameter: 0.15, 0.20, or 0.25 mm). A paste-free control slurry (relative enamel abrasion (REA) value 2) and toothpaste slurries with different abrasivity (REA values 6 or 9) were used for brushing. Erosion and abrasion were followed by storing the enamel samples in artificial saliva for 3 h. After each 4th cycle, the samples were stored in artificial saliva for 15 h. After 60 cycles, enamel loss was measured by profilometry and statistically analyzed by two-way and one-way ANOVA and Bonferroni/Dunn post-hoc tests. RESULTS: Loss of enamel (mean, microm) was influenced mainly by the abrasivity of the slurry and increased along with REA value (REA 2: 0.0-0.2, REA 6: 2.1-3.3, REA 9: 2.9-3.7). Abrasion of eroded enamel was also affected by filament stiffness of the toothbrush, but only groups brushed with toothpaste slurry of REA 6 showed any significant difference between the different toothbrushes. Thereby, toothbrushes with 0.2 mm filament diameter caused higher enamel loss than 0.15 and 0.25 mm filaments. CONCLUSIONS: Toothbrush abrasion of eroded enamel is influenced mainly by the abrasivity of the toothpaste slurry, but is also modified by toothbrush filament stiffness.

[Nutrition, diet and dental health--de- and remineralisation of teeth]. / Ernährung, Nahrungsmittel und Zahngesundheit-- De- und Remineralisation der Zähne.

There is little if any evidence that nutrition during the time of tooth formation has any clinically significant effect on caries susceptibility of erupted teeth in man. Caries, erosion and demastication are not nutritional diseases. They are, however, diet-related diseases because erupted teeth are subject to local chemical and mechanical effects of the diet contacting the teeth. Caries is the result of a chronic undermining demineralisation of the teeth by organic acids that are produced by the bacteria of the dental biofilm while fermenting carbohydrates from the human diet. Dental erosion is the result of a chronic localised loss of dental hard tissue etched away from the surface by acids derived from the diet or from gastric reflux. The physicochemical grounds of de- and remineralisation of teeth are explained using detailed diagrams. Initial caries lesions without cavitation of the surface can remineralise (heal) under conditions of low cariogenic diet and good oral hygiene. However, once the surface has broken and cavitation occurred, there is no alternative to restorative dental therapy because remineralisation is no more possible.