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Background Synthetic particulate hydroxyapatite (HAP; Ca5(PO4)3(OH)) is used as ingredient in oral care products but its effects on cariogenic biofilms are not clear yet. The primary mode of action of HAP may be acting as a calcium phosphate reservoir when deposited in oral biofilms and release Ca2+ and (hydrogen) phosphate ions upon bacterial acid challenge. The aim of this in vitro study was to test this hypothesis by investigating release of Ca2+ ions and potential buffering effects from HAP upon bacterial acid challenge in planktonic cultures and biofilms of Streptococcus mutans. Methods Planktonic cultures of S. mutans were grown in BHI broth with 1% sucrose or with additional 5% HAP or 5% silica for up to 48 h. Separately, biofilms of S. mutans were grown in BHI for 72 h in total. After 24 h of this biofilm culture, either BHI alone or BHI with additional 0.5% HAP or 0.5% silica was added. After 48 h, BHI with 1% sucrose was added to allow bacterial acid formation. Ca2+ release was determined colorimetrically and pH measurements were performed using a pH electrode. For statistical analysis, non-parametrical procedures were applied (n ≥ 10; Mann-Whitney U test; α = 0.05). Results Relevant release of Ca2+ was only evident in planktonic cultures or biofilms with HAP but not in both other groups (p ≤ 0.001). In suspended biofilms with HAP, median pH was 4.77 after 72 h and about 0.5 pH units higher as compared to both other groups (4.28 or 4.32, respectively; p ≤ 0.001). Conclusions Under the tested conditions, synthetic HAP releases Ca2+ ions upon bacterial acid challenge and may also show some buffering capacity but further studies are needed to investigate whether the concentrations tested here can also be reached clinically in dental biofilms.

Objectives To evaluate the clinical performance of two flowable composites for restoring Class-V non-carious cervical lesions (NCCLs), one with novel (ND; N’Durance ® Dimer Flow, Septodont) and one with modified conventional matrix composition (FS; Filtek™ Supreme XTE Flow, 3M-ESPE). The null hypothesis was that both flowable composites perform equally regarding clinical quality and survival. Methods 50 patients received one ND and one FS restoration of NCCLs in premolars using Clearfil Protect Bond (Kuraray) as an adhesive. Restorations were evaluated by two examiners at baseline (BL), 18 and 36 months employing FDI criteria. Non-parametric statistical analyses and χ 2 tests were applied ( α = 0.05). Results 48 patients with both restorations under risk participated in the 36-mo recall. One patient terminated participation after the 18-mo recall. One ND restoration failed at the 18-mo recall (fracture). One FS restoration failed during clinical examination at the 36-mo recall (debonding). 95.8% of restorations each were rated clinically acceptable at 36-mo. No significant differences for all selected FDI criteria were recorded between ND and FS at each examination time point except for the criteria surface staining at 36-mo and marginal staining at 18-mo and 36-mo, where FS showed significantly better results. For each material, no significant differences over time were detected, except for loss of surface lustre for FS (BL to 18 months). Significance Within the limitations of the study, the null hypothesis that materials perform equally could not be rejected. Both flowable composites performed equally regarding survival and similarly regarding clinical performance.

OBJECTIVES To investigate the additional influence of either antimicrobial photodynamic therapy (aPDT; Helbo® Photodynamic Systems) or local application of minocycline microspheres (MC; Arestin, OraPharma) on clinical and microbiological healing results in deep periodontal pockets (PPD ≥6 mm) following non-surgical periodontal therapy (SRP). MATERIALS AND METHODS Forty-five patients with chronic periodontitis were evaluated: test group aPDT + SRP (n = 15), positive control group MC + SRP (n = 15), and negative control group SRP-alone (n = 15). Clinical and microbiological healing parameters were recorded in every patient for four experimental teeth at baseline, 6 weeks, and 3, 6, and 12 months. Wilcoxon signed-rank test and Mann-Whitney U test were used for statistical analysis (α = 0.05). RESULTS Significant improvements in clinical and microbiological parameters were found for all groups after 6 weeks and 3, 6, and 12 months. Differences between groups were not statistically significant. Changes after 12 months [median (25/75%)] are as follows: reduction in PPD [mm]: aPDT + SRP 2 (1/3), MC + SRP 3 (1/4), SRP-alone 2 (1/3); percentage of residual BOP positive teeth [%]: aPDT + SRP 75 (25/100), MC + SRP 33.3 (0/50), SRP-alone 66.7 (25/75). CONCLUSIONS Within the limitations of this study, neither the applied aPDT system nor MC showed a significant additional influence on clinical and microbiological healing outcomes in deep periodontal pockets compared to SRP alone. CLINICAL RELEVANCE In deep periodontal defects, the efficacy of non-surgical periodontal treatment seems not to be improved by adjunctive use of antimicrobial photodynamic therapy or minocycline microspheres.

For caries‐active patients, antimicrobial measures may be useful in addition to mechanical biofilm removal. The aim of this study was to investigate the antimicrobial efficacy of alternative compounds for use in oral care from two main categories (i.e., preservatives and natural compounds) toward biofilms from caries‐associated bacteria as compared to oral care gold‐standards chlorhexidine digluconate (CHX), cetylpyridinium chloride (CPC), and zinc. Compounds were screened in initial Streptococcus mutans biofilms. Then, the most effective compounds were further investigated in mature S. mutans and polymicrobial biofilms comprising Actinomyces naeslundii, Actinomyces odontolyticus, and S. mutans. Here, distinct treatment periods and concentrations were evaluated. Biofilms were visualized by scanning electron microscopy and bacterial membrane damage was evaluated by means of flow cytometry and staining with SYBR Green and propidium iodide. Citrus extract was the only compound exhibiting similar antimicrobial efficacy in initial S. mutans biofilms (>5 log10) as compared to CHX and CPC, but its effect was clearly inferior in mature S. mutans and polymicrobial biofilms. Flow cytometric data suggested that the mechanism of antimicrobial action of citrus extract may be based on damage of bacterial membranes similar to CHX and CPC. From all alternative compounds investigated in this study, citrus extract exhibited the highest antimicrobial efficacy toward in vitro biofilms from caries‐associated bacteria, but still was less effective than oral care gold‐standard antiseptics CHX and CPC. Nevertheless, citrus extract may be a valuable antimicrobial compound for use in oral care for caries‐active patients.

AIM To investigate the clinical long-term outcomes 13 years following guided tissue regeneration (GTR) in deep intra-bony defects with and without additional application of autogenous platelet concentrate (APC). METHODS In 25 patients, two deep contra-lateral intra-bony defects were treated according to GTR using β-TCP and bio-resorbable membranes. In test defects, APC was applied additionally. After 13 years, clinical healing results were assessed and compared to results at baseline and after 1 year. Furthermore, a tooth survival analysis was carried out. RESULTS After 13 years, 22 patients were available for tooth survival analysis showing 81.8% of test and 86.4% of control teeth still in situ. Based on the 15 patients still available for split-mouth analysis, median CAL was 10.0 mm in test and 12.0 mm in control sites at baseline. After 1 year, both groups revealed significant CAL gains of 5.0 mm, followed by a new CAL loss of 1.0 mm in the following 12 years. There were no significant differences between test and control sites. CONCLUSION Within the limits of this study, the data show that most of the CAL gain following GTR can be maintained over 13 years. The additional use of APC had no positive influence on the long-term stability.

Antimicrobial photodynamic therapy (aPDT) may be useful as a supportive antimicrobial measure for caries-active subjects. In this study, the antimicrobial efficacy of aPDT with a phenalen-1-one photosensitizer was evaluated in a novel in vitro biofilm model comprising Actinomyces naeslundii, Actinomyces odontolyticus, and Streptococcus mutans and was compared to chlorhexidine. The proposed biofilm model allows high-throughput screening for antimicrobial efficacy while exhibiting a differentiated response to different antimicrobial approaches. While chlorhexidine 0.2% showed a reduction of ≈4 log10 for all species, aPDT led to a more pronounced reduction of S. mutans (2.8 log10) than of Actinomyces spp. (1.2 or 1.3 log10). A similar effect was also observed in monospecies biofilms. Therefore, aPDT may be more effective against S. mutans than against Actinomyces spp. when in biofilms, and this antimicrobial approach merits further investigations.

Aim: Five photoactive compounds with variable elongated alkyl-substituents in a phenalen-1-one structure were examined in view of structural similarity to the antimicrobial agent benzalkonium chloride (BAC). Methods: All phenalen-1-ones and BAC were evaluated for their antimicrobial properties against Staphylococcus aureus, methicillin-resistant S. aureus, Escherichia coli, Pseudomonas aeruginosa and for their eukaryotic toxicity against normal human epidermal keratinocyte (NHEK) cells to narrow down the BAC-like effect and the photodynamic effect depending on the chemical structure. All compounds were investigated for effective concentration ranges, where a bacterial reduction of 5 log10 is achieved, while an NHEK survival of 80% is ensured. Results: Effective concentration ranges were found for four out of five photoactive compounds, but not for BAC and the compound with BAC-like alkyl chain length. Conclusion: Chain length size and polar area of the respective head-groups of phenalen-1-one compounds or BAC showed an influence on the incorporation inside lipid membranes and thus, head-groups may have an impact on the toxicity of antimicrobials.

Aim: Resistances to antibiotics employed for treatment of infectious diseases have increased to alarming numbers making it more and more difficult to treat diseases caused by microorganisms resistant to common antibiotics. Consequently, novel methods for successful inactivation of pathogens are required. In this instance, one alternative could be application of light for treatment of topical infections. Antimicrobial properties of UV light are well documented, but due to its DNA-damaging properties use for medical purposes is limited. In contrast, irradiation with visible light may be more promising. Methods: Literature was systematically screened for research concerning inactivation of main oral bacterial species by means of visible light. Results: Inactivation of bacterial species, especially pigmented ones, in planktonic state showed promising results. There is a lack of research examining the situation when organized as biofilms. Conclusion: More research concerning situation in a biofilm state is required.

Objectives To evaluate the clinical performance of two flowable composites for restoration of Class-V non-carious cervical lesions (NCCLs), one with novel (N’Durance® Dimer Flow, Septodont; ND) and one with modified conventional matrix composition (Filtek™ Supreme XTE Flow, 3M-ESPE; FS). The null hypothesis was that both flowable composite materials perform equally regarding clinical quality and survival. Methods 50 patients received one ND and one FS restoration of NCCLs in premolars using Clearfil Protect Bond (Kuraray) as an adhesive without additional selective enamel etching. Restorations were evaluated at baseline (BL), after 30 and 60 months employing selected original FDI criteria and refined FDI criteria by separate evaluation of enamel and dentine margins. Non-parametric statistical analyses and χ2 tests were applied (α = 0.05). Results 38 patients with both restorations under risk were available for the 60-mo recall (recall rate: 76%). At 60-mo, 94.7% of ND and 84.2% of FS restorations were rated clinically acceptable. No significant differences for all selected FDI criteria were recorded between ND and FS at each examination time point except for the criteria surface lustre at 60-mo, where FS showed significantly better results. No significant differences over time could be detected for both materials. There was a trend for more deterioration along the enamel margins than along the dentine margins (criteria marginal staining and marginal adaptation). Significance Within the limitations of the study, the null hypothesis that materials perform equally could not be rejected. Both flowable composites performed similarly regarding clinical performance.

Increasing antibiotic resistances in microorganisms create serious problems in public health. This demands alternative approaches for killing pathogens to supplement standard treatment methods. Photodynamic inactivation of bacteria (PIB) uses light activated photosensitizers (PS) to generate reactive oxygen species immediately upon illumination, inducing lethal phototoxicity. Positively charged phenalen-1-one derivatives are a new generation of PS for light-mediated killing of pathogens with outstanding singlet oxygen quantum yield ΦΔ of97%. Upon irradiation with a standard photopolymerizer light (bluephase C8, 1260 ± 50 mW/cm(2)) the PS showed high activity against the oral key pathogens Enterococcus faecalis, Actinomyces naeslundii, Streptococcus mutans, and Aggregatibacter actinomycetemcomitans. At a concentration of 10 μM, a maximum efficacy of more than 6 log10 steps (≥ 99.9999%) of bacteria killing is reached in less than 1 min (light dose 50 J/cm(2)) after one single treatment. The pyridinium substituent as positively charged moiety is especially advantageous for antimicrobial action.

Prevention and control of biofilm-growing microorganisms are serious problems in public health due to increasing resistances of some pathogens against antimicrobial drugs and the potential of these microorganisms to cause severe infections in patients. Therefore, alternative approaches that are capable of killing pathogens are needed to supplement standard treatment modalities. One alternative is the photodynamic inactivation of bacteria (PIB). The lethal effect of PIB is based on the principle that visible light activates a photosensitizer, leading to the formation of reactive oxygen species, e.g., singlet oxygen, which induces phototoxicity immediately during illumination. SAPYR is a new generation of photosensitizers. Based on a 7-perinaphthenone structure, it shows a singlet oxygen quantum yield ΦΔ of 99% and is water soluble and photostable. Moreover, it contains a positive charge for good adherence to cell walls of pathogens. In this study, the PIB properties of SAPYR were investigated against monospecies and polyspecies biofilms formed in vitro by oral key pathogens. SAPYR showed a dual mechanism of action against biofilms: (I) it disrupts the structure of the biofilm even without illumination; (II) when irradiated, it inactivates bacteria in a polymicrobial biofilm after one single treatment with an efficacy of ≥99.99%. These results encourage further investigation on the potential of PIB using SAPYR for the treatment of localized infectious diseases.

Light-mediated killing of pathogens by cationic photosensitizers (PS) is a promising antimicrobial approach avoiding resistance as being present upon the use of antibiotics. In this study we focused on the impact of the substituents in phenalen-1-one PS. Photodynamic efficacy depending on positively charged moieties including a primary aliphatic, quaternary aliphatic, aromatic ammonium and a guanidinium cation was investigated against Gram-positive and Gram-negative pathogens. Considering the altered steric demand and lipophilicity of these functional groups we deduced a structure–activity relationship. SAGUA was the most potent PS in this series reaching a maximum efficacy of ≥6log10 steps of bacteria killing at a concentration of 10 μM upon irradiation with blue light (20 mW cm−2) for 60 s (1.2 J cm−2) without exhibiting inherent dark toxicity. Its guanidinium moiety may be able to form strong bidentate and directional hydrogen bonds to carboxylate groups of bacterial surfaces in addition to ionic charge attraction. This may supplement fast and effective antimicrobial activity.

Due to increasing resistance of pathogens toward standard antimicrobial procedures, alternative approaches that are capable of inactivating pathogens are necessary in support of regular modalities. In this instance, the photodynamic inactivation of bacteria (PIB) may be a promising alternative. For clinical application of PIB it is essential to ensure appropriate comparison of given photosensitizer (PS)-light source systems, which is complicated by distinct absorption and emission characteristics of given PS and their corresponding light sources, respectively. Consequently, in the present study two strategies for adjustment of irradiation parameters were evaluated: (i) matching energy doses applied by respective light sources (common practice) and (ii) by development and application of a formula for adjusting the numbers of photons absorbed by PS upon irradiation by their corresponding light sources. Since according to the photodynamic principle one PS molecule is excited by the absorption of one photon, this formula allows comparison of photodynamic efficacy of distinct PS per excited molecule. In light of this, the antimicrobial photodynamic efficacy of recently developed PS SAPYR was compared to that of clinical standard PS Methylene Blue (MB) regarding inactivation of monospecies biofilms formed by Enterococcus faecalis and Actinomyces naeslundii whereby evaluating both adjustment strategies. PIB with SAPYR exhibited CFU-reductions of 5.1 log10 and 6.5 log10 against E. faecalis and A. naeslundii, respectively, which is declared as a disinfectant efficacy. In contrast, the effect of PIB with MB was smaller when the applied energy dose was adjusted compared to SAPYR (CFU-reductions of 3.4 log10 and 4.2 log10 against E. faecalis and A. naeslundii), or there was even no effect at all when the number of absorbed photons was adjusted compared to SAPYR. Since adjusting the numbers of absorbed photons is the more precise and adequate method from a photophysical point of view, this strategy should be considered in further studies when antimicrobial efficacy rates of distinct PS-light source systems are compared.

Objectives To investigate the influence of autogenous platelet concentrate (APC) on the long-term regeneration outcome 7 years after guided tissue regeneration (GTR) in deep intrabony periodontal defects. Material and methods In 25 patients, two deep contra-lateral intrabony defects were treated according to GTR (randomized split-mouth-design). In the test defects, APC was additionally applied. After 7 years, healing results were assessed clinically by a blinded examiner and compared to baseline and 12-months results. Furthermore, a tooth survival analysis was performed. Results After 7 years, 23 patients were available for survival analysis and 16 patients for split-mouth analysis; 84% of the test and control teeth were still in situ. In both groups, the median attachment level of 10.5 mm [(25/75%): test 9.0/13.0, control 10.0/12.0] at baseline was significantly (p ≤ 0.05) reduced to 6.0 mm [test 4.0/6.8, control 5.0/7.0] after 1 year. Six years later, it had increased again to 7.0 mm in test sites [5.3/10.0] (p ≤ 0.05) and had remained stable in control sites [5.0/7.8] (p > 0.05). Bleeding on Probing (BOP) had increased in both groups. During the last 6 years, only 26% of the patients received a structured supportive periodontal therapy in the clinic. Conclusion Within its limitations, the present study indicates that the clinical outcome of GTR therapy can be maintained over 7 years. However, the additional use of APC may even have a possibly negative influence on the long-term stability.