Influence of Layer Thickness and Shade on the Transmission of Light through Contemporary Resin Composites.

BACKGROUND: Material-dependent parameters have an important impact on the efficiency of light polymerization. The present in vitro study aimed to investigate the influence of the increment thickness and shade of nano- and nanohybrid resin composites on the transmission of curing light. METHODS: Three contemporary resin composites were evaluated: Tetric EvoCeram® (TEC); Venus Diamond® (VD); and Filtek Supreme XTE® (FS XTE). Light transmission (LT) was recorded in accordance with the sample thickness (0.5 to 2.7 mm) and the shade. Polymerized samples were irradiated for 10 s each using the high-power LED curing light Celalux 2 (1900 mW/cm2). LT was simultaneously recorded using the MARC Patient Simulator (MARC-PS). RESULTS: LT was strongly influenced by the composite layer thickness. For 0.5 mm-thick samples, a mean power density of 735 mW/cm2 was recorded at the bottom side. For the 2.7 mm samples, a mean power density of 107 mW/cm2 was measured. Only LT was markedly reduced in the case of darker shades. From A1 to A4, LT decreased by 39.3% for FS XTE and 50.8% for TEC. Dentin shades of FS XTE and TEC (A2, A4) showed the lowest LT. CONCLUSIONS: The thickness and shade of resin composite increments strongly influences the transmission of curing light. More precise information about these parameters should be included in the manufacture manual.

Influence of the orthodontic bonding procedure on biofilm formation.

INTRODUCTION: In orthodontics, white spot lesions are a persistent and widespread problem caused by the demineralization of buccal tooth surfaces around bonded brackets. The remaining adhesive around the brackets leads to surface roughness, which might contribute to demineralization. The present in vitro study aimed to compare a conventional and a modern adhesive system (APC Flash-Free technology) for orthodontic brackets with regard to the adhesion of Streptococcus sobrinus, a leading caries pathogen. METHODS: This in vitro study included 20 premolar teeth and compared 10 APC Flash-Free adhesive-coated ceramic brackets (FF)with 10 conventionally bonded (CB) ceramic clarity brackets. Specimens were incubated in an S. sobrinus suspension for 3 h. To evaluate the bacterial formation, samples were analysed with a scanning electron microscope (SEM). Imaging software was used to quantify and statistically compare percentage values of colonization (PVC) in both groups' adhesion and transition areas. RESULTS: We found a significant difference in biofilm formation between the groups for the adhesive and transition areas. PVC in the adhesive area was approximately 10.3-fold greater for the CB group compared with the FF group (median: 3.2 vs 0.31; P < 0.0001). For the transition area, median PVC was approximately 2.4-fold greater for the CB group compared with the FF group (median: 53.17 vs 22.11; P < 0.01). CONCLUSIONS: There was a significantly lower level of S. sobrinus formation around the FF bracket system than there was surrounding the conventionally bonded group. This study suggests that the FF adhesive bracket system can help reduce the occurrence of bacterial growth around orthodontic brackets.

Photodynamic Suppression of Enterococcus Faecalis in Infected Root Canals with Indocyanine Green, TroloxTM and Near-Infrared Light.

Recently, our group showed that additional supplementation of Trolox™ (vitamin E analogue) can significantly enhance the antimicrobial photodynamic effect of the photosensitizer Indocyanine green (ICG). Up to now, the combined effect has not yet been investigated on Enterococcus faecalis in dental root canals. In the present in vitro study, eighty human root canals were inoculated with E. faecalis and subsequently subjected to antimicrobial Photodynamic Therapy (aPDT) using ICG (250, 500, 1000 µg/mL) and near-infrared laser light (NIR, 808 nm, 100 Jcm-2). Trolox™ at concentrations of 6 mM was additionally applied. As a positive control, irrigation with 3% NaOCl was used. After aPDT, root canals were manually enlarged and the collected dentin debris was subjected to microbial culture analysis. Bacterial invasion into the dentinal tubules was verified for a distance of 300 µm. aPDT caused significant suppression of E. faecalis up to a maximum of 2.9 log counts (ICG 250 µg/mL). Additional application of TroloxTM resulted in increased antibacterial activity for aPDT with ICG 500 µg/mL. The efficiency of aPDT was comparable to NaOCl-irrigation inside the dentinal tubules. In conclusion, ICG significantly suppressed E. faecalis. Additional application of TroloxTM showed only minor enhancement. Future studies should also address the effects of TroloxTM on other photodynamic systems.

Salivary Pellicle Formed on Dental Composites Evaluated by Mass Spectrometry-An In Situ Study.

(1) Background: In the oral environment, sound enamel and dental restorative materials are immediately covered by a pellicle layer, which enables bacteria to attach. For the development of new materials with repellent surface functions, information on the formation and maturation of salivary pellicles is crucial. Therefore, the present in situ study aimed to investigate the proteomic profile of salivary pellicles formed on different dental composites. (2) Methods: Light-cured composite and bovine enamel samples (controls) were exposed to the oral cavity for 30, 90, and 120 min. All samples were subjected to optical and mechanical profilometry, as well as SEM surface evaluation. Acquired pellicles and unstimulated whole saliva samples were analyzed by SELDI-TOF-MS. The significance was determined by the generalized estimation equation and the post-hoc bonferroni adjustment. (3) Results: SEM revealed the formation of homogeneous pellicles on all test and control surfaces. Profilometry showed that composite surfaces tend to be of higher roughness compared to enamel. SELDI-TOF-MS detected up to 102 different proteins in the saliva samples and up to 46 proteins in the pellicle. Significant differences among 14 pellicle proteins were found between the composite materials and the controls. (4) Conclusions: Pellicle formation was material- and time-dependent. Proteins differed among the composites and to the control.

Osseointegration of photodynamic active biomaterials for bone regeneration in an animal bone model over a period of 12 months.

OBJECTIVES: Previous efforts led to the development of two different polymeric biomaterials for periodontal regeneration with antibacterial photodynamic surface activity. The present study aimed to investigate osseointegration and bone formation of both materials in an ovine model. METHODS: Both biomaterials: 1) urethane dimethacrylate-based Biomaterial 1 (BioM1) and 2) tri-armed oligoester-urethane methacrylate-based Biomaterial 2 (BioM2) are enriched with beta-tri-calcium phosphate and the photosensitizer meso-tetra(hydroxyphenyl)chlorin (mTHPC). These materials were implanted in non-critical size bone defects in the sheep femur (n = 16) and tibia (n = 8). Empty defects served as controls (n = 16). Polyfluorochrome sequential bone labeling was carried out at baseline and after 3, 6, and 12 months. Animals were sacrificed after 12 months. Bone specimens (n = 40) were fixed and subjected to microtomographic analysis (µCT) for the evaluation of the bone-volume-fraction (BV/TV), trabecular number and trabecular thickness. Subsequently, histological sections were arranged and polyfluorochrome sequential bone labeling was analyzed by confocal laser scanning microscopy (cLSM). RESULTS: cLSM analysis revealed that highest remodeling and bone formation activity occurred during the second half of the study period (6-12 months). Bone formation in the tibia was significantly lower for the control (2.71 ± 1.26%) as compared to BioM1 (6.01 ± 2.99%) and BioM2 (6.45 ± 2.12%); (p = 0.006, p = 0004). Micro-computed tomography revealed a BV/TV volume fraction of 44.72 ± 9.01% in femur defects filled with BioM1 which was significantly higher compared to the control (32.27 ± 7.02%; p = 0.01). Bone architecture (trabecular number, trabecular thickness) did not significantly differ from the self-healed defects. SIGNIFICANCE: Both biomaterials, especially BioM1 showed good osseointegration and bone formation characteristics and can be recommended for further examination in periodontal regeneration studies.

Immunometabolic capacities of nutritional fatty acids in regulation of inflammatory bone cell interaction and systemic impact of periodontal infection.

Introduction: Novel preventive strategies in periodontal disease target the bacterial-induced inflammatory host response to reduce associated tissue destruction. Strategies focus on the modulation of tissue-destroying inflammatory host response, particularly the reduction of inflammation and promotion of resolution. Thereby, nutrition is a potent immunometabolic non-pharmacological intervention. Human studies have demonstrated the benefit of olive oil-containing Mediterranean-style diets (MDs), the main component of which being mono-unsaturated fatty acid (FA) oleic acid (OA (C18:1)). Hence, nutritional OA strengthened the microarchitecture of alveolar trabecular bone and increased circulating pro-resolving lipid mediators following bacterial inoculation with periodontal pathogen Porphyromonas gingivalis, contrary to saturated FA palmitic acid (PA (C16:0)), which is abundant in Western-style diets. Additionally, the generalized distribution of inflammatory pathway mediators can occur in response to bacterial infection and compromise systemic tissue metabolism and bone homeostasis distant from the side of infection. Whether specific FA-enriched nutrition and periodontal inoculation are factors in systemic pathology that can be immune-modulatory targeted through dietary substitution is unknown and of clinical relevance. Methods: Normal-weight C57BL/6-mice received OA-or PA-enriched diets (PA-ED, OA-ED, PA/OA-ED) or a normal-standard diet (n=12/group) for 16 weeks and were orally infected with P. gingivalis/placebo to induce periodontal disease. Using histomorphometry and LC-MS/MS, systemic bone morphology, incorporated immunometabolic FA-species, serological markers of bone metabolism, and stress response were determined in addition to bone cell inflammation and interaction in vitro. Results: In contrast to OA-ED, PA-ED reduced systemic bone microarchitecture paralleled by increased lipotoxic PA-containing metabolite accumulation in bone. Substitution with OA reversed the bone-destructive impact of PA, which was accompanied by reduced diacylglycerols (DAG) and saturated ceramide levels. Further, PA-associated reduction in mineralization activity and concomitant pro-inflammatory activation of primary osteoblasts were diminished in cultures where PA was replaced with OA, which impacted cellular interaction with osteoclasts. Additionally, PA-ED increased osteoclast numbers in femurs in response to oral P. gingivalis infection, whereas OA-ED reduced osteoclast occurrence, which was paralleled by serologically increased levels of the stress-reducing lipokine PI(18:1/18:1). Conclusion: OA substitution reverses the bone-destructive and pro-inflammatory effects of PA and eliminates incorporated lipotoxic PA metabolites. This supports Mediterranean-style OA-based diets as a preventive intervention to target the accumulation of PA-associated lipotoxic metabolites and thereby supports systemic bone tissue resilience after oral bacterial P. gingivalis infection.

Influence of Different Bracket Adhesive Systems on Enamel Demineralization-An In Vitro Study.

BACKGROUND: enamel demineralization is a common side effect of orthodontic therapy with fixed braces. The aim of the present in vitro study was to compare a conventional adhesive system and a modern adhesive system (APC Flash-Free [FF] technology) with regard to the demineralization of enamel by Streptococcus sobrinus (S. sobrinus). METHODS: this in vitro study included premolar teeth and compared APC FF adhesive brackets (Group A, n = 15) with conventional adhesive brackets (Group B, n = 15) from the same company. Specimens were incubated with a positive control group (PCG, n = 5) and a negative control group (NCG, n = 5) in an S. sobrinus suspension for three weeks. To evaluate the grade of enamel demineralization, the samples were analyzed using a polarizing microscope. RESULTS: the test specimens of group B with conventionally bonded bracket adhesive showed significantly greater (+10.8 µm) demineralization with regard to the penetration depth of the demineralization than the PCG (p = 0.012). Thus, there was a difference from group A with the new bracket adhesive of the FF brackets (+7.29 µm). Significantly, demineralization was more pronounced cervically than coronally in both groups, and it occurred cervically more frequently than grade 3 demineralization (p = 0.001). CONCLUSIONS: it seems plausible that new orthodontic bracket adhesives and the modern FF adhesive system positively contribute to the reduction in enamel demineralization during orthodontic treatment.

Histological and Histomorphometric Evaluation of Implanted Photodynamic Active Biomaterials for Periodontal Bone Regeneration in an Animal Study.

Recently, our group developed two different polymeric biomaterials with photodynamic antimicrobial surface activity for periodontal bone regeneration. The aim of the present study was to analyze the biocompatibility and osseointegration of these materials in vivo. Two biomaterials based on urethane dimethacrylate (BioM1) and tri-armed oligoester-urethane methacrylate (BioM2) that additionally contained ß-tricalcium phosphate and the photosensitizer mTHPC (meso-tetra(hydroxyphenyl)chlorin) were implanted in non-critical size bone defects in the femur (n = 16) and tibia (n = 8) of eight female domestic sheep. Bone specimens were harvested and histomorphometrically analyzed after 12 months. BioM1 degraded to a lower extent which resulted in a mean remnant square size of 17.4 mm², while 12.2 mm² was estimated for BioM2 (p = 0.007). For BioM1, a total percentage of new formed bone by 30.3% was found which was significant higher compared to BioM2 (8.4%, p < 0.001). Furthermore, BioM1 was afflicted by significant lower soft tissue formation (3.3%) as compared to BioM2 (29.5%). Additionally, a bone-to-biomaterial ratio of 81.9% was detected for BioM1, while 8.5% was recorded for BioM2. Implantation of BioM2 caused accumulation of inflammatory cells and led to fibrous encapsulation. BioM1 (photosensitizer-armed urethane dimethacrylate) showed favorable regenerative characteristics and can be recommended for further studies.

Effects of reducing excess dental adhesive on bacterial adhesion in the bracket periphery.

OBJECTIVES: White spot lesions are one of the most common side effects of orthodontic therapy with a multibracket appliance and may indicate a preliminary stage of caries, also known as initial caries. Several approaches may be utilized to prevent these lesions, such as reducing bacterial adhesion in the area surrounding the bracket. This bacterial colonization can be adversely affected by a number of local characteristics. In this context, the effects of excess dental adhesive in the bracket periphery were investigated by comparing a conventional bracket system with the APC flash-free bracket system. MATERIALS AND METHODS: Both bracket systems were applied to 24 extracted human premolars, and bacterial adhesion with Streptoccocus sobrinus (S. sobrinus) was performed for 24 h, 48 h, 7 d, and 14 d. After incubation, bacterial colonization was examined in specific areas by electron microscopy. RESULTS: Overall, significantly fewer bacterial colonies were found in the adhesive area around the APC flash-free brackets (n = 507 ± 13 bacteria) than the conventionally bonded bracket systems (n = 850 ± 56 bacteria). This is a significant difference (**p = 0.004). However, APC flash-free brackets tend to create marginal gaps with more bacterial adhesion in this area than conventional bracket systems (n = 265 ± 31 bacteria). This bacterial accumulation in the marginal-gap area is also significant (*p = 0.029). CONCLUSION: A smooth adhesive surface with minimal adhesive excess is beneficial for reducing bacterial adhesion but also poses a risk of marginal gap formation with subsequent bacterial colonization, which can potentially trigger carious lesions. CLINICAL RELEVANCE: To reduce bacterial adhesion, the APC flash-free bracket adhesive system with low adhesive excess might be beneficial. APC flash-free brackets reduce the bacterial colonization in the bracket environment. A lower number of bacteria can minimize white spot lesions in the bracket environment. APC flash-free brackets tend to form marginal gaps between the bracket adhesive and the tooth.

Coaxial electrospun nanofibers as drug delivery system for local treatment of periodontitis.

OBJECTIVES: The aim of the present study was to prepare resorbable polylactide fibers for periodontitis treatment using coaxial electrospinning to optimize the release of metronidazole (MNA) by reducing the initial burst effect. METHODS: Poly(L-lactide-co-D,L-lactide) (PLA) fibers mats with different distributions of metronidazole (MNA) were manufactured by coaxial electrospinning (COAX). By COAX spinning the central core of the fiber was enriched with 40% MNA (m/m), while the sheath of the fiber consisted of PLA only (test group). In contrast, fibers of the control group were prepared by conventional electrospinning with the same amount of MNA but with a homogenous drug distribution (HDD - homogenously distributed drug). The release of MNA was determined by analyzing aliquots from the fiber mats using UV-VIS spectroscopy. Agar diffusion tests were carried out to determine the antibacterial effect on periodontopathogenic bacteria. Biocompatibility was tested in direct contact to human gingival fibroblasts (HGF) for two days. RESULTS: The COAX mats showed a retarded drug release compared to the conventional HDD fibers. After 24 h, 64% of total MNA was released cumulatively from the COAX fibers while 90% of the MNA was released from the HDD fibers (controls). The antibacterial effect of COAX fibers was significantly higher after 24 h compared to the HDD fibers. Cell cultivation revealed significant higher numbers of vital cells among the COAX mats. SIGNIFICANCE: COAX fibers showed improved sustained MNA release compared to conventional fibers and can be seen as potential drug delivery systems in local periodontitis treatment.

Mediterranean diet component oleic acid increases protective lipid mediators and improves trabecular bone in a Porphyromonas gingivalis inoculation model.

AIM: Therapeutic modulation of bacterial-induced inflammatory host response is being investigated in gingival inflammation and periodontal disease pathology. Therefore, dietary intake of the monounsaturated fatty acid (FA) oleic acid (OA (C18:1)), which is the main component of Mediterranean-style diets, and saturated FA palmitic acid (PA (C16:0)), which is a component of Western-style diets, was investigated for their modifying potential in an oral inoculation model of Porphyromonas gingivalis. MATERIALS AND METHODS: Normal-weight C57BL/6-mice received OA- or PA-enriched diets (PA-ED, OA-ED, PA/OA-ED) or normal standard diet for 16 weeks and were inoculated with P. gingivalis/placebo (n = 12/group). Gingival inflammation, alveolar bone structure, circulating lipid mediators, and in vitro cellular response were determined. RESULTS: FA treatment of P. gingivalis-lipopolysaccharide-incubated gingival fibroblasts (GFbs) modified inflammatory activation, which only PA exacerbated with concomitant TNF-α stimulation. Mice exhibited no signs of acute inflammation in gingiva or serum and no inoculation- or nutrition-associated changes of the crestal alveolar bone. However, following P. gingivalis inoculation, OA-ED improved oral trabecular bone micro-architecture and enhanced circulating pro-resolving mediators resolvin D4 (RvD4) and 4-hydroxydocosahexaenoic acid (4-HDHA), whereas PA-ED did not. In vitro experiments demonstrated significantly improved differentiation in RvD4- and 4-HDHA-treated primary osteoblast cultures and reduced the expression of osteoclastogenic factors in GF. Further, P. gingivalis infection of OA-ED animals led to a serum composition that suppressed osteoclastic differentiation in vitro. CONCLUSIONS: Our results underline the preventive impact of Mediterranean-style OA-EDs by indicating their pro-resolving nature beyond anti-inflammatory properties.

Remineralization of Artificially Demineralized Human Enamel and Dentin Samples by Zinc-Carbonate Hydroxyapatite Nanocrystals.

(1) Background: Decalcified enamel and dentin surfaces can be regenerated with non-fluoride-containing biomimetic systems. This study aimed to investigate the effect of a zinc carbonate-hydroxyapatite-containing dentifrice on artificially demineralized enamel and dentin surfaces. (2) Methods: Human enamel and dentin discs were prepared and subjected to surface demineralization with 30% orthophosphoric acid for 60 s. Subsequently, in the test group (n = 20), the discs were treated three times a day for 3 min with a zinc carbonate-hydroxyapatite-containing toothpaste (biorepair®). Afterwards, all samples were gently rinsed with PBS (5 s) and stored in artificial saliva until next use. Samples from the control group (n = 20) received no dentifrice-treatment and were stored in artificial saliva, exclusively. After 15 days of daily treatment, specimens were subjected to Raman spectroscopy, energy-dispersive X-ray micro-analysis (EDX), white-light interferometry, and profilometry. (3) Results: Raman spectroscopy and white-light interferometry revealed no significant differences compared to the untreated controls. EDX analysis showed calcium phosphate and silicon dioxide precipitations on treated dentin samples. In addition, treated dentin surfaces showed significant reduced roughness values. (4) Conclusions: Treatment with biorepair® did not affect enamel surfaces as proposed. Minor mineral precipitation and a reduction in surface roughness were detected among dentin surfaces only.

Clinical effects of laser-based cavity preparation on class V resin-composite fillings.

The aim of the present clinically controlled two-year study was to investigate the influence of laser-based cavity preparation on the long-term performance of Class V resin-composite fillings. Class V non-carious lesions (n = 75) were randomly assigned to two test and one control group. Cavities in both test groups were prepared using an Er,Cr:YSGG laser (Waterlase MD, Biolase, Irvine, California, USA). The device was operated at 3 W (150 mJ, 30 J/cm2), 50% water, 60% air, 30 Hz in H mode. Subsequently, laser-prepared tooth surfaces in test group I (n = 21) were additionally conditioned by acid etching (etch-and-rinse). Laser-prepared cavities of test group II (n = 21) received no additional acid conditioning. After application of an adhesive, all cavities were restored using the resin-composite Venus®. For cavities in the control group (n = 33) conventional diamond burs were used for preparation which was followed by an etch-and-rinse step, too. The fillings were evaluated immediately (baseline) and after 6, 12 and 24 months of wear according to the C-criteria of the USPHS-compatible CPM-index. The results showed that after 24 month of wear, laser-preparation was associated with fillings of high clinical acceptability. Compared to conventional bur-based treatment, laser-based cavity preparation resulted in fillings with high marginal integrity and superior marginal ledge configurations (p = 0.003). Furthermore, laser-preparation combined with additional acid-conditioning (test group I) resulted in fillings with the best marginal integrity and the lowest number in marginal discoloration, especially at the enamel-composite margins (p = 0.044). In addition, total loss of fillings was also less frequently observed in both laser groups as compared to the control. The results clearly demonstrate that laser-based cavity preparation will benefit the clinical long-time performance of Class V resin-composite fillings. Furthermore, additional acid-conditioning after laser preparation is of advantage.

Effectiveness of Casein Phosphopeptide-Amorphous Calcium Phosphate (CPP-ACP) Compared to Fluoride Products in an In-Vitro Demineralization Model.

The goal of this study was to evaluate the effectiveness of the toothpaste Tooth Mousse compared to conventional fluoride-based versions in the prevention of enamel and dentin demineralization. Human enamel and dentin samples (n = 120 each) were exposed to artificial demineralization at pH 4.92. During the demineralization process, the samples in the test groups were periodically treated with Tooth Mousse (TM) containing casein-phosphopeptide -amorphous-calcium-phosphate (CPP-ACP) and Tooth Mousse Plus (TMP) containing amorphous-calcium-fluoride-phosphate (CPP-ACPF) to evaluate their protective properties. Fluoride toothpastes containing 1400 ppm amine fluoride (AmF) and 1450 ppm sodium fluoride (NaF) were applied in the positive control groups. Treatment with distilled water (group C-W) or demineralization without treatment (group C-D) served as negative controls. After the demineralization and treatment process, all samples were cut longitudinally and lesion depths were determined at six locations using polarized light microscopy. In TM/TMP groups (enamel: 80/86 µm, dentin: 153/156 µm) lesion depths were significantly smaller compared to the negative control groups C-W/C-D (enamel: 99/111 µm, dentin: 163/166 µm). However, TM and TMP compared to the positive controls AmF/NaF (enamel: 58/63 µm, dentin: 87/109 µm) showed higher lesion depths. The application of TM/TMP (89%/78%) during demineralization led to a reduced number of severe lesions compared to the negative controls C-W/C-D (100%/95%). In this study we demonstrate that Tooth Mousse is less effective regarding prevention of enamel and dentin demineralization compared to fluoride containing toothpastes.

Critical parameters in cultivation of experimental biofilms using the example of Pseudomonas fluorescens.

Formation and treatment of biofilms present a great challenge for health care and industry. About 80% of human infections are associated with biofilms including biomaterial centered infections, like infections of prosthetic heart valves, central venous catheters, or urinary catheters. Additionally, biofilms can cause food and drinking water contamination. Biofilm research focusses on application of experimental biofilm models to study initial adherence processes, to optimize physico-chemical properties of medical materials for reducing interactions between materials and bacteria, and to investigate biofilm treatment under controlled conditions. Exploring new antimicrobial strategies plays a key role in a variety of scientific disciplines, like medical material research, anti-infectious research, plant engineering, or wastewater treatment. Although a variety of biofilm models exist, there is a lack of standardization for experimental protocols, and designing experimental setups remains a challenge. In this study, a number of experimental parameters critical for material research have been tested that influence formation and stability of an experimental biofilm using the non-pathogenic model strain of Pseudomonas fluorescens. These parameters include experimental time frame, nutrient supply, inoculum concentration, static and dynamic cultivation conditions, material properties, and sample treatment during staining for visualization of the biofilm. It was shown, that all tested parameters critically influence the experimental biofilm formation process. The results obtained in this study shall support material researchers in designing experimental biofilm setups.

Antibacterial Effect of Endodontic Disinfections on Enterococcus Faecalis in Dental Root Canals-An In-Vitro Model Study.

Enterococcus faecalis (E. faecalis) is rather unsusceptible to many root canal disinfections which often cause a therapeutic problem. Therefore, the present in vitro study observed the efficiency of different endodontic antiseptics in their capability to suppress E. faecalis, especially inside dentinal tubules. Prior to any testing, root canals of extracted third human molars were inoculated with E. faecalis for 48 h. Antiseptic dressings with chloramine-T or calcium hydroxide (CaOH) for 24 h or irrigations with 1.3% sodium hypochlorite (NaOCl) were applied with n = 10 in each group. As control irrigation with normal saline was used. All treated canals were manually enlarged from size ISO 50 to 110 and the ablated dentin debris was subjected to microbial culture analysis. Bacterial colonization of the dentinal tubules up to 300 µm was verified by scanning electron microscopy and histological sample preparation. Application of crystalline chloramine-T caused total bacterial suppression inside the dentinal tubules. Dressings with CaOH showed only minor effects. Irrigation with NaOCl caused total eradication of bacteria adhering to the root canal walls, but also failed to completely suppress E. faecalis inside the dentinal tubules. The study showed that chloramine-T is of strong antiseptic activity and also efficient in suppressing E. faecalis inside dentinal tubules.

Antimicrobial Effect of Natural Berry Juices on Common Oral Pathogenic Bacteria.

(1) Background: Antimicrobial agents such as chlorhexidine (CHX) are commonly used in oral plaque control. However, sometimes those agents lack antimicrobial efficiency or cause undesired side effects. To identify alternative anti-infective agents, the present study investigated the antibacterial activity of all-fruit juices derived from blackcurrant, redcurrant, cranberry and raspberry on common oral pathogenic gram-positive and gram-negative bacteria (Streptococcus mutans, Streptococcus gordonii, Streptococcus sobrinus, Actinomyces naeslundii, Fusobacterium nucleatum, Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Enterococcus faecalis). (2) Methods: Antibacterial efficiency was evaluated by agar diffusion assay and in direct contact with bacteria in planktonic culture. Furthermore, cytotoxicity on human gingival fibroblasts was determined. (3) Results: Blackcurrant juice was most efficient at suppressing bacteria; followed by the activity of redcurrant and cranberry juice. Raspberry juice only suppressed P. gingivalis significantly. Only high-concentrated blackcurrant juice showed minimal cytotoxic effects which were significantly less compared to the action of CHX. (4) Conclusion: Extracts from natural berry juices might be used for safe and efficient suppression of oral pathogenic bacterial species.

Effect of biomimetic mineralization on enamel and dentin: A Raman and EDX analysis.

OBJECTIVE: To investigate the effect of an experimental biomimetic mineralization kit (BIMIN) on the chemical composition and crystallinity of caries-free enamel and dentin samples in vitro. METHODS: Enamel and dentin samples from 20 human teeth (10 for enamel; 10 for dentin) were divided into a control group without treatment and test samples with BIMIN treatment. Quantitative analysis of tissue penetration of fluoride, phosphate, and calcium was performed using energy-dispersive X-ray spectroscopy (EDX). Mineralization depth was measured by Raman spectroscopy probing the symmetric valence vibration near 960cm-1 as a marker for crystallinity. EDX data was statistically analyzed using a paired t-test and Raman data was analyzed using the Student's t-test. RESULTS: EDX analysis demonstrated a penetration depth of fluoride of 4.10±3.32µm in enamel and 4.31±2.67µm in dentin. Calcium infiltrated into enamel 2.65±0.64µm and into dentin 5.58±1.63µm, while the penetration depths for phosphate were 4.83±2.81µm for enamel and 6.75±3.25µm for dentin. Further, up to 25µm of a newly mineralized enamel-like layer was observed on the surface of the samples. Raman concentration curves demonstrated an increased degree of mineralization up to 5-10µm into the dentin and enamel samples. SIGNIFICANCE: Biomimetic mineralization of enamel and dentin samples resulted in an increase of mineralization and a penetration of fluoride into enamel and dentin.

Bactericidal and Biocompatible Properties of Plasma Chemical Oxidized Titanium (TiOB®) with Antimicrobial Surface Functionalization.

Coating of plasma chemical oxidized titanium (TiOB®) with gentamicin-tannic acid (TiOB® gta) has proven to be efficient in preventing bacterial colonization of implants. However, in times of increasing antibiotic resistance, the development of alternative antimicrobial functionalization strategies is of major interest. Therefore, the aim of the present study is to evaluate the antibacterial and biocompatible properties of TiOB® functionalized with silver nanoparticles (TiOB® SiOx Ag) and ionic zinc (TiOB® Zn). Antibacterial efficiency was determined by agar diffusion and proliferation test on Staphylocuccus aureus. Cytocompatibility was analyzed by direct cultivation of MC3T3-E1 cells on top of the functionalized surfaces for 2 and 4 d. All functionalized surfaces showed significant bactericidal effects expressed by extended lag phases (TiOB® gta for 5 h, TiOB® SiOx Ag for 8 h, TiOB® Zn for 10 h). While TiOB® gta (positive control) and TiOB® Zn remained bactericidal for 48 h, TiOB® SiOx Ag was active for only 4 h. After direct cultivation for 4 d, viable MC3T3-E1 cells were found on all surfaces tested with the highest biocompatibility recorded for TiOB® SiOx Ag. The present study revealed that functionalization of TiOB® with ionic zinc shows bactericidal properties that are comparable to those of a gentamicin-containing coating.

Critical physiological factors influencing the outcome of antimicrobial testing according to ISO 22196 / JIS Z 2801.

Bactericidal materials gained interest in the health care sector as they are capable of preventing material surfaces from microbial colonization and subsequent spread of infections. However, commercialization of antimicrobial materials requires proof of their efficacy, which is usually done using in vitro methods. The ISO 22196 standard (Japanese test method JIS Z 2801) is a method for measuring the antibacterial activity of daily goods. As it was found reliable for testing the biocidal activity of antimicrobially active materials and surface coatings most of the laboratories participating in this study used this protocol. Therefore, a round robin test for evaluating antimicrobially active biomaterials had to be established. To our knowledge, this is the first report on inaugurating a round robin test for the ISO 22196 / JIS Z 2801. The first round of testing showed that analyses in the different laboratories yielded different results, especially for materials with intermediate antibacterial effects distinctly different efficacies were noted. Scrutinizing the protocols used by the different participants and identifying the factors influencing the test outcomes the approach was unified. Four critical factors influencing the outcome of antibacterial testing were identified in a series of experiments: (1) incubation time, (2) bacteria starting concentration, (3) physiological state of bacteria (stationary or exponential phase of growth), and (4) nutrient concentration. To our knowledge, this is the first time these parameters have been analyzed for their effect on the outcome of testing according to ISO 22196 / JIS Z 2801. In conclusion, to enable assessment of the results obtained it is necessary to evaluate these single parameters in the test protocol carefully. Furthermore, uniform and robust definitions of the terms antibacterial efficacy / activity, bacteriostatic effects, and bactericidal action need to be agreed upon to simplify communication of results and also regulate expectations regarding antimicrobial tests, outcomes, and materials.