Markus Jörg Altenburger

Cleanliness of dentinal tubules following gutta-percha removal with and without solvents: a scanning electron microscopic study.

AIM To determine the influence of solvents on gutta-percha and sealer remaining on root canal walls and in dentinal tubules. METHODOLOGY The root canals of 70 teeth were prepared chemomechanically to apical size 40. In group 1 (n = 10; control group), the canals remained unfilled. In groups 2-4 (n = 20 each), the canals were filled using lateral compaction with gutta-percha and sealer. Removal of root fillings was undertaken after 2 weeks using Gates Glidden burs and hand files without solvent (group 2), with eucalyptol (60 microL; group 3) and with chloroform (60 microL; group 4) to size 50. After further irrigation using sodium hypochlorite and ethylenediaminetetraacetic acid, the roots were split, photographed and scanning electron microscopy (SEM) was performed. The number of filled dentinal tubules (SEM) and the surface covered by root filling remnants (photographs) were evaluated for the coronal, middle and apical third of each root half. Statistical analysis was performed via mixed model for clustered data followed by Tukeys test. RESULTS After pooling the results of all thirds of the canal, open tubules were more prevalent in the control group, followed by the nonsolvent group, the eucalyptol group and the chloroform group (P < 0.05 between all groups). Less surface was covered by root filling remnants in the nonsolvent group than in the eucalyptol group and the chloroform group (P < 0.05); again, fewer remnants were found in the control group than in all other groups (P < 0.05). CONCLUSIONS Solvents led to more gutta-percha and sealer remnants on root canal walls and inside dentinal tubules.

New Bacterial Composition in Primary and Persistent/Secondary Endodontic Infections with Respect to Clinical and Radiographic Findings

INTRODUCTION The aim of the present study was to analyze the microbiota of primary and secondary/persistent endodontic infections of patients undergoing endodontic treatment with respect to clinical and radiographic findings. METHODS Samples from the root canals of 21 German patients were taken using 3 sequential sterile paper points. In the case of a root canal filling, gutta-percha was removed with sterile files, and samples were taken using sterile paper points. The samples were plated, and microorganisms were then isolated and identified morphologically by biochemical analysis and sequencing the 16S rRNA genes of isolated microorganisms. RESULTS In 12 of 21 root canals, 33 different species could be isolated. Six (50%) of the cases with isolated microorganisms were primary, and 6 (50%) cases were endodontic infections associated with root-filled teeth. Twelve of the isolated species were facultative anaerobic and 21 obligate anaerobic. Monomicrobial infections were found for Enterococcus faecalis and Actinomyces viscosus. E. faecalis was most frequently isolated in secondary endodontic infections (33%). Moraxella osloensis was isolated from a secondary endodontic infection that had an insufficient root canal filling accompanied by a mild sensation of pain. A new bacterial composition compromising Atopobium rimae, Anaerococcus prevotii, Pseudoramibacter alactolyticus, Dialister invisus, and Fusobacterium nucleatum was recovered from teeth with chronic apical abscesses. CONCLUSIONS New bacterial combinations were found and correlated to clinical and radiographic findings, particularly to chronic apical abscesses. M. osloensis was detected in root canals for the second time and only in German patients.

Effects of various forms of calcium added to chewing gum on initial enamel carious lesions in situ.

The purpose of this randomized, cross-over in situ study was to determine the effects of 4 chewing gums on artificial caries-like subsurface lesions. Two chewing gums (1 with zinc citrate and 1 without) contained dicalcium phosphate (3.9%), calcium gluconate (1.8%) and calcium lactate (0.45%), 1 chewing gum contained casein phosphopeptide-amorphous calcium phosphate nanocomplexes (0.7%), and another one contained no calcium. Fifteen subjects without current caries activity (7 male, 8 female; mean age: 27.5 ± 2.5 years) wore removable buccal appliances in the lower jaw with 4 bovine enamel slabs with subsurface lesions. The appliances were inserted immediately before gum chewing for 20 min and then retained for an additional 20 min. This was performed 4 times per day. Every subject chewed 4 different chewing gums over 4 periods of 14 days each. During a fifth period (control) the subjects only wore the appliances without chewing gum. At completion of each period the enamel slabs were embedded, sectioned and subjected to transversal microradiography. With regard to change of mineral loss and of lesion depth no significant differences could be found between chewing gums containing calcium and calcium-free chewing gums. Moreover, the chewing gum groups and the control group did not differ significantly if adjustments were made for baseline values (p > 0.05; ANCOVA). Under the conditions of the present study it may be concluded that the use of chewing gum offers no additional remineralizing benefit to buccal tooth surfaces, even if the chewing gum contains calcium compounds.

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.

Bacterial and Candida albicans Adhesion on Different Root Canal Filling Materials and Sealers

INTRODUCTION Microbial adhesion and subsequent biofilm formation on endodontic root canal filling materials and sealers lead to survival of microorganisms in treated root canals and subsequently to endodontic treatment failures. The present study focused on initial microbial adhesion to different endodontic filling materials. METHODS The following endodontic biomaterials were tested: AH-Plus, Tubli Seal, gutta-percha, Real Seal SE, EndoREZ, Apexit Plus, GuttaFlow, and dentin. Samples of each material were prepared. Bovine dentin samples were used as a control. The initial adhesions of salivary bacteria as well as the subsequent single species were quantified by determination of colony-forming units (CFUs) and visualized by scanning electron microscopy and confocal microscopy (CLSM): Enterococcus faecalis, Streptococcus mutans, Streptococcus sanguis, Candida albicans, and Prevotella nigrescens. RESULTS Initially adherent microorganisms could be detected and microscopically visualized on each of the materials tested. Considering the values of the CFUs and the covering grade as detected by CLSM, there were significant differences among the materials. Fewer bacteria tended to adhere to Apexit Plus, whereas Real Seal SE and the widely used gutta-percha showed the highest number of adherent bacteria. This tendency was not detected for C. albicans. CONCLUSIONS Endodontic microorganisms have a high affinity to root canal filling materials and sealers, especially to gutta-percha. Because of this high level of bacterial adhesion, subsequent biofilm formation on these materials could be suggested as leading to the persistence of microorganisms in root canals.

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.

Evaluation of an improved endodontic teaching model: do preclinical exercises have an influence on the technical quality of root canal treatments?

AIM To investigate whether the preclinical application of an electronic root canal length measurement device (ERCLMD) leads to more accurate working length (WL) determinations in a preclinical endodontic course and if this exercise effects the technical quality of root canal procedures when treatments are performed on patients for the first time. METHODOLOGY Root canal treatments performed by two consecutive groups of third year students (group 1: n = 39, group 2: n = 44) were compared in the preclinical course and when root canal treatments were performed on patients in the following term. Two different teaching models were applied in the preclinical endodontic course. WL in group 1 was determined with radiographs only. The teaching model applied in group 2 allowed the application of an ERCLMD. When treatments were performed on patients, both groups used the same technique to determine WL. It was first determined using an ERCLMD and verified radiographically. Master cone and root filling lengths were evaluated using radiographs, and comparisons between both groups were made using Fischers exact test. RESULTS Root fillings performed by students of group 2 were more often classified as acceptable. This observation was made in the preclinical endodontic course and when treatments were performed on patients. CONCLUSIONS The application of an ERCLMD in combination with radiographs is more accurate to determine WL than radiographs alone. Students practiced the use of ERCLMDs with the new model and benefited from this experience when performing their first root canal treatments on patients.