Effects of Final Irrigation with SmearOFF on the Surface of Dentin Using Surface Analytical Methods.

INTRODUCTION: SmearOFF (Vista Dental Products, Racine, WI) is an irrigation solution containing chlorhexidine (CHX), EDTA, and a surfactant. This study examined the chemical interaction of SmearOFF with sodium hypochlorite (NaOCl) on the dentin surface, specifically the formation of precipitate and/or parachloroanaline (PCA). METHODS: Dentin blocks prepared from human maxillary molars were mounted in resin. Dentinal tubules were exposed in a perpendicular orientation using an ultracryomicrotome. The blocks were divided into 2 groups: the CHX group, irrigation with 6% NaOCl, 17% EDTA, 6% NaOCl, and 2% CHX, and the SmearOFF group, irrigation with 6% NaOCl and SmearOFF. The dentin surface was analyzed with time-of-flight secondary ion mass spectrometry and X-ray photoelectron spectroscopy to determine the formation of precipitate or/and PCA on the surface of dentin. RESULTS: Precipitation with PCA and occlusion of the dentinal tubules were noted on the dentin surface in the CHX group. No precipitate and no PCA were detected on the surface of dentin in the SmearOFF group. CONCLUSIONS: Interaction of SmearOFF with NaOCl on the dentin surface did not result in the formation of precipitate or PCA.

Qualitative Time-of-Flight Secondary Ion Mass Spectrometry Analysis of Root Dentin Irrigated with Sodium Hypochlorite, EDTA, or Chlorhexidine.

INTRODUCTION: Sodium hypochlorite (NaOCl), chelating agents, and chlorhexidine (CHX), which are commonly used irrigants during endodontic treatment, have the potential to alter the physical and chemical properties of the dentin structure. The aim of this study was to use time-of-flight secondary ion mass spectrometry to qualitatively evaluate the chemical characteristics of dentin surface and compare it with dentin exposed to NaOCl, EDTA, or CHX. METHODS: Four blocks of dentin from a root of a human maxillary molar were embedded in resin and trimmed with a microtome to expose the dentin. Samples were randomly assigned to 4 treatment groups: (1) no irrigation treatment (sample A), (2) 2.5% NaOCl (sample B), (3) 17% EDTA (sample C), and (4) 2% CHX (sample D). Dentin surfaces were analyzed by time-of-flight secondary ion mass spectrometry, which allowed characterization of dentin surface chemistry by both imaging and mass spectroscopic analysis obtained in high mass and spatial resolution modes. RESULTS: Sample A revealed intense peaks characteristics of hydroxyapatite in addition to Na(+), K(+), CH4N(+), CN(-), CNO(-), Mg(+), F(-), and HCO2(-) peaks. Sample B showed severely decreased CH4N(+) and increased intensity of Cl(-). Sample C lacked Ca(+) and Mg(+) and showed decreased PO2(-) and PO3(-). Sample D exhibited a distinct presence of CHX. The spectral image of sample A displayed even distribution of Na(+) and Ca(+) on a smeared surface. The surfaces of samples B and D had patent dentinal tubules, whereas sample D showed an intense CHX signal. Sample C had some patent dentinal tubules and lacked Ca(+). CONCLUSIONS: NaOCl removed protein components from the dentin matrix, EDTA removed calcium and magnesium ions from the dentin, and CHX formed an adsorbed layer on the dentin surface.

Qualitative analysis of precipitate formation on the surface and in the tubules of dentin irrigated with sodium hypochlorite and a final rinse of chlorhexidine or QMiX.

INTRODUCTION: Interaction of sodium hypochlorite (NaOCl) mixed with chlorhexidine (CHX) produces a brown precipitate containing para-chloroaniline (PCA). When QMiX is mixed with NaOCl, no precipitate forms, but color change occurs. The aim of this study was to qualitatively assess the formation of precipitate and PCA on the surface and in the tubules of dentin irrigated with NaOCl, followed either by EDTA, NaOCl, and CHX or by saline and QMiX by using time-of-flight secondary ion mass spectrometry (TOF-SIMS). METHODS: Dentin blocks were obtained from human maxillary molars, embedded in resin, and cross-sectioned to expose dentin. Specimens in group 1 were immersed in 2.5% NaOCl, followed by 17% EDTA, 2.5% NaOCl, and 2% CHX. Specimens in group 2 were immersed in 2.5% NaOCl, followed by saline and QMiX. The dentin surfaces were subjected to TOF-SIMS spectra analysis. Longitudinal sections of dentin blocks were then exposed and subjected to TOF-SIMS analysis. All samples and analysis were performed in triplicate for confirmation. RESULTS: TOF-SIMS analysis of group 1 revealed an irregular precipitate, containing PCA and CHX breakdown products, on the dentin surfaces, occluding and extending into the tubules. In TOF-SIMS analysis of group 2, no precipitates, including PCA, were detected on the dentin surface or in the tubules. CONCLUSIONS: Within the limitations of this study, precipitate containing PCA was formed in the tubules of dentin irrigated with NaOCl followed by CHX. No precipitates or PCA were detected in the tubules of dentin irrigated with NaOCl followed by saline and QMiX.

Microbial biofilm proliferation within sealer-root dentin interfaces is affected by sealer type and aging period.

INTRODUCTION: Root canal fillings are intended to prevent microbial proliferation over time in the canal after treatment. The objective of this study was to assess biofilm proliferation within the sealer-dentin interfaces of 2 methacrylate resin-based systems, self-etch (SE) and total-etch (TE), and an epoxy resin-based sealer (EP), aged for up to 6 months. METHODS: Standardized specimens (n = 45) comprising the coronal 5 mm of human roots were filled with the test materials and gutta-percha. Specimens were either not preincubated (control, n = 9) or were incubated in sterile saline for 1 week, 1 month, 3 months, or 6 months (n = 3/group). Monospecies biofilms of Enterococcus faecalis were grown on the specimens for 7 days in a chemostat-based biofilm fermentor mimicking pathogenic oral conditions. The extent of E. faecalis proliferation within the sealer-dentin interface for each material and incubation period group was assessed by using fluorescence microscopy of dihydroethidium-stained specimens. RESULTS: TE had less biofilm proliferation than both EP and SE (P < .01). Deeper biofilm proliferation was detected in SE and EP specimens aged for 1 and 3 months than those aged for 1 week or 6 months (P < .05). Maximum depth of biofilm penetration was recorded for SE at 1 month (P < .05). CONCLUSIONS: Within the test model used, the SE and EP sealers were more susceptible to interfacial biofilm proliferation than the TE restorative material. This susceptibility diminished after aging the materials' interfaces for 6 months.

The operating microscope enhances detection and negotiation of accessory mesial canals in mandibular molars.

INTRODUCTION: Detection and negotiation of accessory mesial canals in mandibular molars was investigated with the aid of magnifying loupes or the operating microscope. METHODS: First and second mandibular molars (n = 96) were mounted in mannequins. Three independent investigators (endodontists) prepared access cavities using 4.5x loupes, attempting to detect and negotiate accessory mesial canals with ultrasonic instruments. If detection or negotiation was unsuccessful, the procedure was continued using the microscope. The location of accessory mesial canals was mapped in relation to the main mesial canals, and their pathway shown with inserted files. The mesial roots were cross-sectioned at three levels to inspect for nonnegotiated accessory mesial canals. RESULTS: With the microscope, the number of detected accessory mesial canals increased from 8 (16%) to 9 (18%) in first molars and from 8 (16%) to 11 (22%) in second molars. Negotiated accessory mesial canals increased from 6 (12%) to 7 (14%) and from 5 (10%) to 9 (18%) in the first and second molars, respectively. All 20 detected accessory mesial canals were located in the mesial subpulpal groove, closer to the mesiolingual canal (45%), in the middle (30%), or closer to the mesiobuccal canal (25%). All negotiated accessory mesial canals merged with one of the main two canals. Cross-sections of the roots confirmed that no accessory canals were present in addition to those negotiated. CONCLUSIONS: Within the limitations of this study, more accessory canals were detected and negotiated when using the microscope compared with loupes. This improvement was more pronounced in second molars than in first molars. All negotiated accessory canals merged with either one of the main mesial canals.

Determination of 4-chloroaniline and its derivatives formed in the interaction of sodium hypochlorite and chlorhexidine by using gas chromatography.

INTRODUCTION: The combination of sodium hypochlorite (NaOCl) and chlorhexidine (CHX) results in the formation of a precipitate. In a previous study, we demonstrated the formation of 4-chloroaniline (PCA) in the precipitate by using x-ray photon spectroscopy (XPS) and time of flight secondary ion mass spectrometry (TOF-SIMS). The TOF-SIMS results showed a peak at 127 amu, which is characteristic of 4-chloroaniline. However, this could also be characteristic of other isomers of 4-chloroaniline such as 2-chloroaniline and 3-chloroaniline. AIMS AND METHODS: The aim of this study was to further identify the precipitate by using gas chromatography-mass spectrometry (GC-MS). RESULTS: The results showed an absence of other aniline derivatives in the precipitate. Only PCA was found. CONCLUSIONS: Further investigations of the precipitate should address the bioavailability of PCA leaching out from dentin and its cytotoxicity. Until the precipitate is studied further, it would appear prudent to minimize its formation by avoiding the use of CHX together with NaOCl.

Antibacterial efficacy of MTAD final rinse and two percent chlorhexidine gel medication in teeth with apical periodontitis: a randomized double-blinded clinical trial.

INTRODUCTION: Clinical assessment of the efficacy of novel root canal disinfection protocols is an important focus in endodontic research. This randomized double-blinded study assessed the antibacterial efficacy of a final rinse with BioPure MTAD (MTAD) and intracanal medication with 2% chlorhexidine gel (CHX) in teeth with apical periodontitis. METHODS: Canals in 30 teeth (single-rooted and multi-rooted) were prepared by using 1.3% NaOCl, rinsed with MTAD or saline in random sequence, medicated with CHX for 7 days, irrigated with 1.3% NaOCl, and filled. Bacteriologic root canal samples were obtained by aspiration before (1A) and after (1B) canal preparation, after the final rinse (1C), after CHX was flushed (2A), and after final irrigation (2B). Bacteria were enumerated by epifluorescence-microscopy (EFM) by using 2 staining methods and by colony-forming-unit (CFU) counts after 14 days of incubation. RESULTS: Bacterial counts (EFM) in 1B were greater than 95% decreased from 1A. Low bacterial densities in 1B, 1C, 2A, and 2B did not differ significantly from each other. EFM counts were consistently higher than CFU counts. CONCLUSIONS: The final rinse with MTAD and medication with CHX did not reduce bacterial counts beyond levels achieved by canal preparation with NaOCl.

Using diazotization to characterize the effect of heat or sodium hypochlorite on 2.0% chlorhexidine.

INTRODUCTION: The combination of sodium hypochlorite (NaOCl) and chlorhexidine (CHX) results in the formation of a precipitate. In a previous study, we demonstrated the formation of 4-chloraniline (PCA) in the precipitate in an amount directly related to the concentration of NaOCl used. AIMS AND METHODS: The aim of the present study was to use a diazotization technique to confirm the presence of an aromatic amine (like PCA) in the NaOCl/CHX precipitate and also in the 2.0% CHX at different temperatures (37 degrees C and 45 degrees C). RESULTS: The results corroborated the presence of the aromatic amine in the precipitate and in the CHX at 45 degrees C. CONCLUSIONS: Further investigations of the precipitate should address the bioavailability of PCA leaching out from dentin and its cytotoxicity. Until the precipitate is studied further, it would appear prudent to minimize its formation.

Characterization of an ex vivo model for the assessment of root canal disinfection.

Root canal bacteria in teeth with apical periodontitis were enumerated after extraction and incubation. Canals in 36 teeth were sampled after: S1, incubation for 2 hours (group A), 2 days (group B), 4 days (group C), and 6 days (group D); S2, subsequent incubation for 1 week; S3, canal disinfection; and S4, final incubation for 1 week. Bacterial concentrations were determined by culture (colony-forming unit [CFU]) and epifluorescence-microscopy (EFM) and compared by using pairwise and exact-permutation tests (p < 0.05). CFU counts were lower than EFM counts. CFU counts in S1 were higher in Gp(A) than in Gp(C) (p < 0.004) and Gp(D) (p < 0.02). EFM counts in S1 were higher in Gp(A) than in Gp(C) (p < 0.02). Both enumeration methods showed bacterial counts decreasing from S1 to S2 (p < 0.04). EFM was superior to culture in this ex vivo model. The indigenous flora survived incubation for 6 days, but the adverse effect of initial access would preclude testing of disinfection protocols that require two sessions.

Treatment outcome in endodontics: the Toronto study--phase 4: initial treatment.

Outcome 4-6 years after initial treatment was assessed for Phase 4 (2000-2001) of the Toronto Study. Of 582 teeth treated, 430 were lost to follow-up (99 discontinuers, 331 dropouts), 15 were extracted, and 137 (32% recall minus 15 extracted teeth) were examined for outcome: healed (no apical periodontitis, signs, symptoms) or diseased. When pooled with Phases 1-3, 439 of 510 teeth (86%) were healed. Logistic regression identified 2 significant (P < or = .05) preoperative outcome predictors: radiolucency (odds ratio [OR], 2.86; confidence interval [CI], 1.56-5.24; healed: absent, 93%; present, 82%) and number of roots (OR, 2.53; CI, 1.25-5.13; healed: single, 93%; multiple, 84%). In teeth with radiolucency, intraoperative complications (OR, 2.27; CI, 1.05-4.89; healed: absent, 84%; present, 69%) and root-filling technique (OR, 1.89; CI, 1.01-3.53; healed: lateral, 77%; vertical, 87%) were additional outcome predictors. A better outcome was suggested for teeth without radiolucency, with single roots, and without mid-treatment complications. The predictive value of root-filling technique in teeth with radiolucency requires validation from randomized controlled trials.

Treatment outcome in endodontics: the Toronto study--phases 3 and 4: orthograde retreatment.

Outcome 4-6 years after retreatment was assessed for Phases 3 and 4 of the Toronto Study. Of 477 teeth retreated, 333 were lost to follow-up, 18 were extracted, and 126 (41% recall, excluding 124 discontinuers) were examined for outcome of healed (periapical index score, < or = 2; no signs or symptoms) or diseased. When pooled with Phases 1 and 2, 187 of 229 teeth (82%) were healed. Logistic regression identified significant (P < or = .05) preoperative outcome predictors: root filling quality (odds ratio [OR], 4.18; confidence interval [CI], 1.72-10.12; healed: inadequate, 88%; adequate, 66%), perforation (OR, 4.01; CI, 1.28-12.62; healed: absent, 87%; present, 56%), and radiolucency (OR, 3.33; CI, 1.19-9.36; healed: absent, 93%; present, 80%). In teeth with radiolucency, outcome predictors were number of treatment sessions (OR, 12.08; CI, 1.84-infinity; healed: one, 100%; > or = 2, 77%) and previous root filling quality (OR, 7.68; CI, 2.36-26.89; healed: inadequate, 86%; adequate, 50%). Outcome was better in teeth with inadequate previous root filling, without perforation and radiolucency. Suggested significance of number of treatment sessions in teeth with radiolucency requires validation from randomized controlled trials.

Interaction between sodium hypochlorite and chlorhexidine gluconate.

The combination of sodium hypochlorite (NaOCl) and chlorhexidine (CHX) results in the formation of a precipitate. The aim of this study was to determine the minimum concentration of NaOCl required to form a precipitate with 2.0% CHX. This was accomplished with a serial dilution technique. X-ray photon spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (TOF-SIMS) were used to qualify and quantify the precipitate. A color change and precipitate were induced in 2.0% CHX by 0.023% and 0.19% NaOCl, respectively. Both XPS and TOF-SIMS showed the presence of para-chloroaniline in an amount directly related to the concentration of NaOCl used. Until this precipitate is studied further, its formation should be avoided by removing the NaOCl before placing CHX into the canal.

VIO II: Video Informativo Odontologico. Ionomeros vitreos. Radiologia panoramica vs seriada. Fracturas radiculares. Incrustaciones esteticas

ESCUELA DE POSGRADO

VIO II: Video Informativo Odontologico. Ionomeros vitreos. Radiologia panoramica vs seriada. Fracturas radiculares. Incrustaciones esteticas

ESCUELA DE POSGRADO