Karl-Thomas Wrbas

Fluoride Uptake and Remineralisation of Enamel Lesions after Weekly Application of Differently Concentrated Fluoride Gels

There is only little information on the remineralising capability of regularly applied highly concentrated fluoride gels. The aim of this in situ study was to test the hypothesis that weekly application of a 1.25% fluoride gel results in a significantly higher fluoride uptake and a significantly higher mineral gain compared to a 0.5% fluoride or a placebo gel, respectively. Thirty-six subjects were included in this double-blind, three-way, crossover, placebo-controlled study and randomly assigned to a treatment scheme. Two weeks before the study, between treatment periods as well as during the study periods, subjects were instructed to abstain from any fluoride source other than the study medication. At the beginning of each of three 4-week periods specimen holders, each containing 10 bovine enamel slabs, were placed in the subjects’ mouths. During the experimental periods the volunteers brushed the specimens with placebo gel, 0.5% fluoride gel or 1.25% fluoride gel once a week. Fluoride uptake was significantly higher after treatment with the 1.25% fluoride gel than after treatment with the 0.5% fluoride gel (p = 0.007) or the placebo gel (p < 0.001). Treatment with 0.5% fluoride gel led to a significantly higher fluoride uptake compared to placebo treatment (p < 0.001). Changes in mineral gain and lesion depth were not statistically significantly different between the three groups. Under the present experimental conditions repeated application of highly concentrated fluoride gels did not promote remineralisation significantly.

Effect of photodynamic therapy (PDT) on Enterococcus faecalis biofilm in experimental primary and secondary endodontic infections

BackgroundTo determine the antibacterial effect of photodynamic Therapy on Enterococcus faecalis (E. faecalis) biofilms in experimentally infected human root canals in primary infections and endodontic retreatments.MethodsOne hundred and sixty single-rooted extracted teeth with one root canal were prepared using ProTaper instruments. Seventy specimens were left without root canal filling and autoclaved. The root canals of another 70 specimens were filled with Thermafil and AH Plus and the root canal fillings were removed after 24 hours using ProTaper D files and plasma sterilized. The specimens were infected with a clinical isolate of E. faecalis for 72 hours. Samples were taken using sterile paper points to determine the presence of E. faecalis in the root canals. The specimens were randomly divided into groups according to their treatment with 20 teeth each and a control. In the PDT group the teeth were treated using PDT, consisting of the photosensitizer toluidine blue and the PDT light source at 635 nm. In the NaOCl (sodium hypochlorite) group the root canals were rinsed with 10 mL of 3% NaOCl. In the NaOCl-PDT group the root canals were rinsed with 10 mL of 3% of sodium hypochlorite and then treated with PDT. Samples were taken after treatments using sterile paper points. Additionally, remaining root canal filling material was recovered from the root canal walls. Survival fractions of the samples were calculated by counting colony-forming units. A one-way analysis of variance (ANOVA) was applied to the data to assess the effect of different treatment techniques.ResultsAntimicrobial treatment of root canals caused a significant reduction of bacterial load in all groups. NaOCl irrigation eliminated E. faecalis most effectively. PDT alone was less effective compared to NaOCl irrigation and the combination of NaOCl irrigation and PDT. CFU levels recovered from the filling material after NaOCl irrigation of the root canals were 10fold higher compared to PDT and the combination of NaOCl irrigation and PDT.ConclusionsPhotodynamic therapy killed E. faecalis in experimental primary endodontic infections and retreated human root canals. PDT is an effective supplement in root canal disinfection, especially in endodontic retreatments.

Apical Quality and Adaptation of Resilon, EndoREZ, and Guttaflow Root Canal Fillings in Combination with a Noncompaction Technique

The objective of this study was to compare the quality of Guttaflow (Coltene/Whaledent, Langenau, Germany), Resilon/Epiphany (Jeneric/Pentron, Kusterdingen, Germany), and EndoREZ (Ultradent Products, Inc, South Jordan, UT) root canal fillings. Thirty single-rooted teeth were randomly assigned to three groups: Resilon/Epiphany, EndoREZ, and Guttaflow. After radiography of the root canal fillings, the roots were sectioned horizontally at the level of 2 mm and 4 mm from the apex. The area of voids and adaptation to canal walls and points were evaluated using light microscopy and calculated through a computer program. The radiographs showed no significant differences between the materials (p > 0.05, Mann-Whitney U test). Evaluation of cross-sections revealed sealer adaptation >99% to the root canals and >98% to the points. Resilon/Epiphany had significantly higher values at 98.8% (standard deviation [SD] = 3.9%) than EndoREZ at 98.7% (SD = 1.1%), and Guttaflow at 98.5 (SD = 2.1%) (p < 0.05, Mann-Whitney U test). The absolute difference compared with Resilon/Epiphany was at 0.84% (0.44%-1.76%) for EndoREZ and at 1.08% for Guttaflow (0.00%-2.08%) (95% confidence interval, Hodges-Lehman). This outcome indicated an effective apical obturation using any of the three materials in combination with a noncompaction technique.

Ultrasonic activation and chemical modification of photosensitizers enhances the effects of photodynamic therapy against Enterococcus faecalis root-canal isolates

BACKGROUND The aim of this study was to evaluate the effect of photodynamic therapy (PDT) on Enterococcus faecalis biofilms in artificially infected root canals using modified photosensitizers and passive ultrasonic activation. METHODS Two hundred and seventy extracted human teeth with one root canal were instrumented utilizing ProTaper files, autoclaved, infected with E. faecalis T9 for 72 h and divided into different groups: irrigation with 3% sodium hypochlorite (NaOCl), 20% ethylenediaminetetraacetic acid (EDTA), or 20% citric acid, PDT without irrigation, PDT accompanied by irrigation with NaOCl, EDTA, or citric acid, PDT using an EDTA-based photosensitizer or a citric-acid-based photosensitizer and PDT with ultrasonic activation of the photosensitizer. A 15 mg/ml toluidine blue served as the photosensitizer, activated by a 100 mW LED light source. Sterile paper points were used for sampling the root canals and dentin chips were collected to assess the remaining contamination after treatment. Samples were cultured on blood agar plates and colony forming units were quantified. RESULTS PDT alone achieved a reduction in E. faecalis counts by 92.7%, NaOCl irrigation alone and combined with PDT by 99.9%. The antibacterial effects increased by the combination of irrigation using EDTA or citric acid and PDT compared to irrigation alone. More than 99% of E. faecalis were killed using PDT with the modified photosensitizers and ultrasonic activation. CONCLUSIONS NaOCl based disinfection achieved the highest antimicrobial effect. Using PDT with an EDTA-based or citric-acid-based phozosensitizer or activating the photosensitizer with ultrasound resulted in a significantly higher reduction in E. faecalis counts compared to conventional PDT.

Antimicrobial photodynamic therapy using visible light plus water-filtered infrared-A (wIRA).

The aim of this study was to investigate the effectiveness of antimicrobial photodynamic therapy (APDT) using visible light together with water-filtered infrared-A (VIS+wIRA) to eradicate single species of planktonic bacteria and micro-organisms during initial oral bacterial colonization in situ. A broadband VIS+wIRA radiator with a water-filtered spectrum in the range 580-1400 nm was used for irradiation. Toluidine blue (TB) was utilized as a photosensitizer at concentrations of 5, 10, 25 and 50 µg ml(-1). The unweighted (absolute) irradiance was 200 mW cm(-2) and it was applied for 1 min. Planktonic cultures of Streptococcus mutans and Enterococcus faecalis were treated with APDT. Salivary bacteria harvested by centrifugation of native human saliva were also tested. In addition, initial bacterial colonization of bovine enamel slabs carried in the mouths of six healthy volunteers was treated in the same way. Up to 2 log(10) of S. mutans and E. faecalis were killed by APDT. Salivary bacteria were eliminated to a higher extent of 3.7-5 log(10). All TB concentrations tested proved to be highly effective. The killing rate of bacteria in the initial oral bacterial colonization was significant (P=0.004) at all tested TB concentrations, despite the interindividual variations found among study participants. This study has shown that APDT in combination with TB and VIS+wIRA is a promising method for killing bacteria during initial oral colonization. Taking the healing effects of wIRA on human tissue into consideration, this technique could be helpful in the treatment of peri-implantitis and periodontitis.

The Effect of Cervical Preflaring Using Different Rotary Nickel-Titanium Systems on the Accuracy of Apical File Size Determination

INTRODUCTION An exact determination of the apical root canal diameter is crucial for correct cleaning and shaping of a root canal. The aim of this study was to investigate the discrepancies of the initial apical root canal diameter and the diameter that is measured by the initial apical file (IAF) after cervical flaring using current rotary nickel-titanium systems. METHODS Mesiobuccal canals of 40 extracted mandibular molars were randomly assigned to four groups. In the first group, root canals were not flared. Root canals of the other groups were preflared using FlexMaster (VDW, Munich, Germany), ProTaper (Dentsply, Konstanz, Germany), or RaCe (FKG Dentaire, Genf, Switzerland) instruments. The tooth length was determined by inserting an ISO 06 K-file to the apical foramen. The working length (WL) was set 1 mm short of the apical foramen. File sizes were increased after binding sensation was felt at the WL. Transversal sections of the WL regions were examined under stereomicroscope, and the diameter of the root canal and the IAF at WL were assessed. RESULTS Canals preflared with RaCe instruments had the lowest discrepancy between the apical root canal diameter and the IAF diameter (15.7 ± 9.7 μm) followed by ProTaper (22.2 ± 11.0 μm) and FlexMaster (35.0 ± 17.2 μm). CONCLUSIONS Preflaring of root canals prevents underestimation of the actual apical root canal diameter. The type of instruments used for preflaring show differences on the accuracy of IAF determination. Preflaring with larger tapered instruments leads to a more accurate apical sizing, and this information is crucial concerning the appropriate final diameter for complete apical shaping.

Combination of apex locator and endodontic motor for continuous length control during root canal treatment.

AIM To compare ex vivo an experimental setup consisting of an electronic apex locator (EAL) and endodontic motor with an established product (Tri Auto ZX) for accuracy of length control during root canal treatment with three different types of files. METHODOLOGY An experimental setup consisting of porous spongy material and an electrolyte was used. Sixty anterior teeth were randomly assigned to six groups. Access cavities were prepared. During root canal treatment, constant length monitoring was performed either with the Tri Auto ZX or the Raypex5 apex locator attached to an endodontic motor (Endo IT professional) using ProTaper, M(two) or FlexMaster files. After root canal preparation the distances between file tip and major apical foramen and file tip and minor apical foramen were measured using a microscope and analysed using two-way anova to evaluate the accuracy of the two systems. RESULTS Distances between the file tip and the major apical foramen were not significantly different between the file systems and the two EALs. In cases treated with FlexMaster significantly larger distances between file tip and minor apical foramen were found compared to M(two) and ProTaper. No significant differences were observed between the two EALs. After preparation of the root canals with the Tri Auto ZX, multiple minor apical foramina were mechanically widened. CONCLUSION With the limitation of this laboratory study the combination of EAL and endodontic motor was as accurate as the Tri Auto ZX system in terms of length control during root canal preparation.