Infected Root Dentin Research Articles

Reparative dentin formation as a possible factor influencing the penetrability of dentin in human teeth with apical periodontitis: an ex vivo study

BackgroundThere is still a lack of knowledge regarding the permeability and configuration of infected root dentin. The aim of this ex vivo study was to compare the dentin penetrability of healthy teeth and necrotic teeth with apical periodontitis by evaluating the penetration of sodium hypochlorite (NaOCl) and to analyze the histopathological features of root dentin.MethodsForty-eight molars were collected and divided into two groups. The clinical diagnosis for one group was pulp necrosis with apical periodontitis and the pulp and periapex were normal in the other group. Forty-eight straight roots were divided into two groups: infected and healthy. First, all root canals were stained with 2% methylene blue to visualize penetration after standard root canal instrumentation and irrigation. Transverse sections were obtained, and the dye penetration parameters were measured. The cross sections were processed to 20–30 μm and stained with hematoxylin and eosin for observation of the histopathological changes in the root dentin.ResultsThe maximum penetration depth, median penetration depth and penetration percentage of NaOCl solutions, in infected root canals were significantly lower than those in healthy root canals. The histopathological analysis showed that the frequency of reparative dentin formation in infected root canals was significantly greater than that in healthy root canals.ConclusionsThe dentin penetrability of teeth with necrotic teeth and apical periodontitis was more superficial during root canal irrigation than that of healthy teeth. The histopathological changes in infected radicular dentin, namely the formation of reparative dentin, might be associated with the lower permeability of dentin tubules in human teeth with apical periodontitis.

Endodontic Instrument’s Single use Policy. A Literature Review

Over the last quarter of the century, the place of the stainless steel endodontic instruments was taken slowly and surely by nickel–titanium files, becoming a “must have” instrument “for root canal treatments, even if steel instruments are still being used, mainly at the inception of the root canal treatment. Dentists increasingly use Nickel-Titanium (Ni-Ti) files for their properties that overlap those of stainless steel instruments in cleaning and giving a proper shape to the canal and the filling subsequently. It is well known the fragility and the rigidity of the steel instruments compared with the Ni-Ti ones. These new instruments also increased the speed of the treatment. In the opinion of the majority of the dentists root canal preparation represents a very important and challenging treatment being in close relationship with the following maneuvers like irrigation and filling [1,2]. The primary reason for instrumentation in case of root canals is that the bulk material contained within it needs to be removed [2] that can be ether pulp tissue, infected root dentine or necrotic debris. Hulsmann considers that these two processes, mechanical instrumentation and chemical treatment, cannot be separated and must go hand in hand, referred to as chemo-mechanical treatment [3,4]. Therefore, root canal instruments are indispensable in root canal therapy, even today in the age of implants, stem cells, biologic 3D printers and lasers. Being so useful, reliable, resistant and ultimately, not cheap, the initially single-use instruments got to be reused by a vast number of practitioners because the legislation wide world is not prohibiting it nor imposing the single-use, with very few exceptions.

Endodontic Instrument’s Single use Policy. A Literature Review

Over the last quarter of the century, the place of the stainless steel endodontic instruments was taken slowly and surely by nickel–titanium files, becoming a “must have” instrument “for root canal treatments, even if steel instruments are still being used, mainly at the inception of the root canal treatment. Dentists increasingly use Nickel-Titanium (Ni-Ti) files for their properties that overlap those of stainless steel instruments in cleaning and giving a proper shape to the canal and the filling subsequently. It is well known the fragility and the rigidity of the steel instruments compared with the Ni-Ti ones. These new instruments also increased the speed of the treatment. In the opinion of the majority of the dentists root canal preparation represents a very important and challenging treatment being in close relationship with the following maneuvers like irrigation and filling [1,2]. The primary reason for instrumentation in case of root canals is that the bulk material contained within it needs to be removed [2] that can be ether pulp tissue, infected root dentine or necrotic debris. Hulsmann considers that these two processes, mechanical instrumentation and chemical treatment, cannot be separated and must go hand in hand, referred to as chemo-mechanical treatment [3,4]. Therefore, root canal instruments are indispensable in root canal therapy, even today in the age of implants, stem cells, biologic 3D printers and lasers. Being so useful, reliable, resistant and ultimately, not cheap, the initially single-use instruments got to be reused by a vast number of practitioners because the legislation wide world is not prohibiting it nor imposing the single-use, with very few exceptions.

Influence of Infected Root Dentin on the Bond Strength of a Self-adhesive Resin Cement.

Aim:The aim of this study was to determine the bond strength (BS) of a self-adhesive resin cement to the contaminated root dentin.Materials and Methods:The crown and apical third of twenty single-rooted teeth were removed. The root canals were flared and 1-mm-thick root sections were obtained. The sections were rinsed, dried, and sterilized. The control group (n=20) was composed of one section of each third, which remained immersed in sterile trypticase soy broth (TSB) for 2 months. The other sections comprised the experimental group (n = 40) and were immersed in a suspension of Enterococcus faecalis. The culture medium was changed at every 4 days for 2 months. The sections were rinsed with distilled water, dried, and the root canal space was filled with the self-adhesive resin cement RelyX™ U200. After 24 h, the push-out test was performed and the types of interface failure were observed on a stereo microscope.Statistical Analysis:Data were statistically analyzed by the nonparametric Mann–Whitney test (α=5%).Results:A significant reduction was observed in the BS of resin cement to the contaminated dentin compared to the healthy dentin, for both thirds analyzed (P < 0.05). The BS was significantly greater at the cervical third compared to the middle third for specimens in the experimental group (P < 0.05). Adhesive and mixed failures were observed more frequently in specimens contaminated with E. faecalis.Conclusion:Bacterial contamination negatively infl uenced the BS of the self-adhesive resin cement to the root dentin, and there was a predominance of adhesive and mixed failures.

Antifungal Effects of Synthetic Human Beta-defensin-3-C15 Peptide on Candida albicans–infected Root Dentin

IntroductionThe aim of this study was to assess the antifungal efficacy of a synthetic human beta-defensin-3-C15 peptide (HBD3-C15) in Candida albicans–infected human root dentin. MethodsStandardized root dentin blocks were prepared (6-mm thick, 0.7-mm-wide canal) from single-rooted human permanent premolars and infected with C. albicans for 3 weeks. They were randomly divided into 4 groups (n = 8/group), and their canals were filled with calcium hydroxide (CH), HBD3-C15 peptide, or chlorhexidine digluconate (CHX, 2%) as disinfectants or saline as control. After 1 week of disinfection, dentinal debris were harvested at depths of 200 and 400 μm from the canal lumen, and incubated in Yeast broth for 72 hours at 37°C. Then, colony-forming units (CFU) were measured to assess the antifungal efficacy of each medicament and analyzed statistically. ResultsAll medicaments showed significantly lower CFU than saline (P < .05), and their antifungal efficacies were similar at both 200- and 400-μm tubular depths (P > .05). HBD3-C15 had similar antifungal efficacy to that of CHX at both depths (P > .05), and both medicaments had significantly lower CFU than CH at both depths (P < .05). ConclusionsIn this ex vivo model of C. albicans–infected human root dentin, the antifungal efficacy of synthetic HBD3-C15 was comparable with CHX.

Photoactivated Polycationic Bioactive Chitosan Nanoparticles Inactivate Bacterial Endotoxins

IntroductionThe current root canal disinfection protocols fail to markedly inactivate bacterial endotoxins from infected root dentin. This study aimed to evaluate the ability of antibacterial photodynamic therapy with chitosan-conjugated rose bengal nanoparticles (CSRBnps) to selectively inactivate endotoxins/lipopolysaccharides (LPSs). MethodsAntimicrobial agents such as calcium hydroxide (Ca[OH]2), chitosan nanoparticles (CSnps), CSRBnps, and methylene blue (MB) were assessed for their ability to neutralize LPSs obtained from Pseudomonas aeruginosa in a time-dependent interaction with/without photoactivation (20 and 40 J/cm2). The inflammatory potential of the treated/untreated LPSs was assessed on macrophage cells (RAW 267.4) using nitric oxide– and enzyme-linked immunosorbent assay (tumor necrosis factor α and interleukin-6 expression)–based analysis. These antimicrobials were tested directly on macrophage cells for cytotoxicity using the mitochondrial activity assay and light microscopy. The data were analyzed using 1-way analysis of variance and the Tukey test. ResultsCSnps were least effective in LPS inactivation. Interluekin-6 expression was reduced only with CSRBnp treatment. CSnps and CSRBnps were completely nontoxic, and MB showed slight toxicity to macrophage cells. Ca(OH)2 was highly cytotoxic (P < .005) even at 30 minutes of exposure. CSRBnps and MB with/without photoactivation significantly inactivated LPSs with reduced nitric oxide and tumor necrosis factor α expression (P < .05). Cell death and detachment after Ca(OH)2 treatment resulted in complete absence of all 3 inflammatory markers. ConclusionsPhotodynamically activated CSRBnps caused significant inactivation of endotoxins and the subsequent reduction of all tested inflammatory markers from activated macrophages. Antimicrobial CSRBnps in combination with photodynamic therapy showed the potential to effectively inactivate bacterial endotoxins.

Photoactivated rose bengal functionalized chitosan nanoparticles produce antibacterial/biofilm activity and stabilize dentin-collagen

Treatment of infected teeth presents two major challenges: persistence of the bacterial-biofilm within root canals after treatment and compromised structural integrity of the dentin hard-tissue. In this study bioactive polymeric chitosan nanoparticles functionalized with rose-bengal, CSRBnp were developed to produce antibiofilm effects as well as stabilize structural-integrity by photocrosslinking dentin-collagen. CSRBnp were less toxic to fibroblasts and had significant antibacterial activity even in the presence of bovine serum albumin. CSRBnp exerted antibacterial mechanism by adhering to bacterial cell surface, permeabilizing the membrane and lysing the cells subsequent to photodynamic treatment. Photoactivated CSRBnp resulted in reduced viability of Enterococcus faecalis biofilms and disruption of biofilm structure. Incorporation of CSRBnp and photocrosslinking significantly improved resistance to degradation and mechanical strength of dentin-collagen (P<0.05). The functionalized chitosan nanoparticles provided a single-step treatment of infected root dentin by combining the properties of chitosan and that of photosensitizer to eliminate bacterial-biofilms and stabilize dentin-matrix. From the Clinical EditorIn this study, bioactive polymeric chitosan nanoparticles functionalized with rose-bengal (a photosensitizer), CSRBnp were developed to produce antibiofilm effects as well as stabilize structural-integrity of dental root dentin by photocrosslinking dentin-collagen, leading to efficient elimination of bacterial-biofilms and stabilization of dentin-matrix.

Effect of three nickel-titanium rotary file techniques on infected root dentin reduction

This study compared the bacterial reduction of in vitro infected root canals after instrumentation by 3 nickel-titanium (NiTi) rotary files with different taper and diameter versus manual stainless steel files. Sixty-four single-rooted human teeth were infected with a suspension of Streptococcus sanguis measured by optical density. Teeth were divided randomly into 4 groups of 16 and prepared with Flexofiles, GT rotary files, HERO 642, and ProFile. Bacterial samplings were performed before (S1), during (S2-S3), and after (S4) instrumentation. All techniques significantly reduced the number of bacterial cells in the root canals (P < .05). There was no significant difference between NiTi and manual instrumentation at S2, S3, or S4. Concerning bacterial reduction, the results suggest that a manual stainless steel file preparation is as efficient as a NiTi rotary instrumentation. Regardless of the root canal preparation technique, its taper, and diameter, the root dentin remained infected and was not bacteria-free at the end of the experiment.

An Immunohistological Study of the Localization of Bacteria Invading Root Pulpal Walls of Teeth with Periapical Lesions

We immunohistologically examined the prevalence and localization of bacteria invading dentinal tubules of the roots of teeth with infected canals. Forty extracted teeth with apical lesions were selected and divided into two groups: a group of untreated teeth and a group of canal-enlarged teeth. The bacteria in the specimens were detected by Brown-Brenn stain and the labeled-streptavidin-biotin method with specific antisera for 16-bacteria. Seventy percent of the examined teeth showed bacteria invading the dentinal tubules of the roots. Fusobacterium nucleatum, Eubacterium alactolyticum, E. nodatum, Lactobacillus casei, and Peptostreptococcus micros were abundant. Even in the canal-enlarged group, invasion of bacteria was observed in 65% of teeth. This study revealed the actual condition of bacteria in infected root dentin and suggested that the canal-enlargement procedure could not completely remove all the bacteria in the infected dentinal tubules of the root.

Sterilization of infected root-canal dentine by topical application of a mixture of ciprofloxacin, metronidazole and minocycline in situ.

The aim of this study was to observe the potential of a mixture of ciprofloxacin, metronidazole and minocycline to kill bacteria in the deep layers of root canal dentine in situ. After the crowns of extracted teeth had been removed, the drug combination (0.5 mg of each drug), or sterile saline, as the control, was placed in the root canals which had been previously irrigated ultrasonically with G4M EDTA. The penetration and bactericidal efficacy were estimated by various procedures as follows. (1) A cell suspension of E. coli was placed into small cavities prepared parallel to the root canals on the cut planes of nine single-rooted teeth. The teeth were then entirely covered with blue inlay wax. At time 0, and at 5h, 24h and 48h after the drug combination had been applied, cells of E. coli were recovered from the cavities by washing the cavities several times with sterile saline solution, and were cultured on the surfaces of heart-infusion (HI) agar plates. Total colony-forming units were tuen counted. Bacterial recoveries decreased with time, and no bacteria were recovered 48 h after application of the drug combination, while bacteria survived in all cases with the controls, (2) After the drug combination or sterile saline had been placed into and sealed in the root canal with blue inlay wax, the teeth were placed into HI agar plates where cells of E. coli had been inoculated. After culturing, a clear zone caused by the inhibition of bacterial growth was observed around the teeth, but not in the control experiment. (3) After sampling infected root dentine of 12 freshly extracted teeth as positive controls, the drug combination (0.5 mg each) was placed in the root canals. No bacteria were recovered from the infected dentine of the root canal wall 24 h after application of the drug combination, except in one case in which a few bacteria were recovered. On the basis of these results, penetration through dentine and antibacterial efficacy of the drug combination can be expected against bacteria infecting the dentine of the root canal wall in situ when the drugs were placed in root canals which had been irrigated ultrasonically.

Predominant obligate anaerobes invading the deep layers of root canal dentine

This study was carried out to investigate the presence and types of bacteria invading the deep layers (0.5-2.0 mm from the surface of the root canal wall) of infected dentine of human root canals by sampling with an anaerobic glove box system the split surfaces of eight freshly extracted teeth. More bacteria were recovered after incubation in an anaerobic glove box than after aerobic incubation in air with 30 per cent CO2. Out of 256 predominant bacterial isolated, 205 isolates (80 per cent) were obligate anaerobes. These findings suggest that the environment of deep layers of endodontic dentinal lesions is anaerobic and favours the growth of anaerobes. Among the obligate anaerobic isolates, strains belonging to Lactobacillus (30 per cent) and Streptococcus (13 per cent) were predominant, followed by Propionibacterium (9 per cent). No strains of obligate anaerobic Gram-negative rods were isolated. The microflora of deep layers of infected root dentine is somewhat similar to that of the deep layers of carious lesions in coronal dentine.