In situ fluoride retention and remineralization of incipient carious lesions after the application of different concentrations of fluoride.

Limited information is available on the time-dependent or dosage-dependent cariostatic efficacy of highly concentrated fluoride compounds. This good clinical practice-conforming, double-blind, placebo-controlled, crossover in situ study tested the hypothesis that a 1.0% amine fluoride fluid is superior to a 0.5% amine fluoride fluid regarding fluoride retention and mineral change in initial caries enamel lesions over a period of 28 d. Fluoride retention was significantly higher after application of the two fluoride fluids compared with placebo but had decreased in both groups to similar levels after only 1 wk. Mineral gain was significantly higher for both verum groups compared with placebo. The use of 1% fluoride fluid resulted in significantly higher remineralization compared with the use of 0.5% fluoride fluid. For both fluoride fluids mineral gain followed a linear relationship with time during the experimental period, indicating a possible further uptake of mineral, even after 4 wk.

Four-year evaluation of a resin composite including nanofillers in posterior cavities.

PURPOSE: The aim of this prospective study was to evaluate the clinical performance of the restorative material Ceram.X in combination with an experimental one-bottle etch-and-rinse adhesive (K-0127). MATERIALS AND METHODS: A single operator placed two Class I or II restorations in molars of 43 patients. One molar was restored with Ceram.X/K-0127 (Dentsply DeTrey), the other one with Tetric Ceram/Syntac Classic (Ivoclar Vivadent). At baseline, after one, two, and four years the restorations were evaluated by a second dentist using modified Ryge's criteria. After four years, 27 patients were examined. RESULTS: In one patient, both restorations (Class II) had to be removed for root canal treatment due to pulpitis. Another Class II Ceram.X restoration (3.8%; 4.3% [1 of 23] of Class II restorations) showed score C with regard to wear/anatomical form. Thus, the cumulative failure rate was 7.4% in the Ceram.X group (8.3% of Class II restorations [2 of 24]) and 3.7% in the Tetric Ceram group (4.2% of Class II restorations [1 of 24]). Furthermore, three restorations (11.5%) in each group showed score B for anatomical form and marginal integrity. Slight marginal discoloration (score B) was found at five Ceram.X restorations (19.2%) and four Tetric Ceram restorations (15.4%). Two restorations (7.7%) in each group showed slight changes in color stability (score B). No sensitivity, recurrent caries, or changes in surface texture were recorded after four years. No statistically significant differences were found between the two restorative materials (p > 0.05). CONCLUSION: After four years of clinical service, 92.6% of Ceram.X/K-0127 and 96.3% of Tetric Ceram/Syntac Classic restorations performed clinically well.

Survival of glass fiber post restorations over 5 years.

PURPOSE: To evaluate the survival of glass fiber reinforced composite post (GFP) restorations and to identify risk factors for restoration failure. METHODS: GFPs of three consecutively placed post systems, two tapered and one parallel-sided, were adhesively luted and the core was built with a resin composite. Teeth served as abutment teeth according to the prosthetic treatment plan. 149 GFP in 121 patients (age: 53 +/- 15 year; 50 men; 71 women) were followed for 5-79 months (mean +/- SD: 50 +/- 21 months). Cox proportional hazards models were used to evaluate the association between several clinical variables and the failure rate. RESULTS: After exclusion of endodontic failures (n = 3), significantly higher failure rates were found for restorations of anterior teeth compared to posterior teeth (hazard regression (HR): 2.8; 95% confidence interval (CI): 1.4; 5.8; P = 0.004). Restorations in teeth with no proximal contacts compared to at least one proximal contact, single crowns compared to fixed partial dentures and less than two remaining cavity walls had a HR of 2.4 (CI: 0.8-7.1), 2.4 (CI: 0.6-8.7), and 1.5 (CI: 0.6-3.8), respectively. However, these correlations were not statistically significant (P > 0.05).

Detection and eradication of microorganisms in root-filled teeth associated with periradicular lesions: an in vivo study.

This study determined the presence of microorganisms by culture and polymerase chain reaction in asymptomatic root-filled teeth with periradicular lesions. Furthermore, a disinfecting regimen using sodium hypochlorite (NaOCl), ethylenediaminetetraacetic acid (EDTA), chlorhexidine digluconate (CHX) irrigation, and calcium hydroxide (Ca(OH)(2)) dressing was assessed. After removal of the root-filling material, specimens of 20 cases undergoing retreatment were sampled. Moreover, the canals were sampled after each step of the disinfecting regimen. Prevalence of microorganisms was 60% by culture and 65% by polymerase chain reaction. In four of those samples (31%), DNA of Enterococcus faecalis was found. After further root canal preparation and irrigation using NaOCl and EDTA, microorganisms could be detected in none of the teeth. Thus, CHX and Ca(OH)(2) could not show further disinfection. In contrast, microorganisms were found in two teeth after the interappointment dressing. It may be concluded that proper root canal preparation and irrigation using NaOCl and EDTA are sufficient for decontamination of the root canal system during endodontic retreatment.

Efficacy of different rotary instruments for gutta-percha removal in root canal retreatment.

The purpose of this study was to evaluate the efficiency of FlexMaster, ProTaper, and RaCe rotary instruments compared with Hedström files for removal of gutta-percha during retreatment. Sixty mandibular premolars with one single straight canal were instrumented with K-type files and filled using cold lateral compaction and sealer. The teeth were randomly divided into four groups of 15 specimens each. After repreparation with Gates Glidden burs and the test instruments the specimens were cleared. The area of remaining gutta-percha/sealer on the root canal wall was measured from two directions. The RaCe group showed significantly less residual obturation material than FlexMaster and Hedström group (p < 0.05; closed test procedure). There was no difference between ProTaper and all other instruments (p > 0.05). ProTaper and RaCe instruments required significantly less time for retreatment than FlexMaster and Hedström files (p < 0.05). One RaCe file, two ProTaper, and two FlexMaster instruments separated. RaCe cleaned obturated canals more effectively than hand files and FlexMaster files.

Coronal leakage of calcium phosphate-based root canal sealers compared with usual sealers.

The purpose of the present study was to compare two experimental calcium phosphate-based sealers with AH Plus, Sealapex, Ketac-Endo and Hermetic with regard to coronal seal. Two standardized artificial canals were prepared in each of 120 blocks of bovine root dentin. The blocks were divided into six groups. All of the 40 canals of each group were filled with gutta-percha and either AH Plus, Hermetic, Ketac-Endo, Sealapex or two different experimental sealers. One canal of one block was filled with gutta-percha and sealer using lateral condensation, whilst the other canal was obturated using Thermafil. The roots were immersed in black ink and thereafter cleared. Maximum linear dye penetration was measured coronally. Statistical analysis was performed by means of the Kruskal-Wallis test for the global null hypothesis and the closed test procedure for pairwise comparisons. With lateral condensation, experimental sealer I was comparable with AH Plus and Hermetic but showed significantly higher penetration depths than Ketac-Endo and Sealapex. Using Thermafil, more leakage was found for experimental sealer I than for AH Plus, Ketac-Endo and Sealapex. Using both techniques, leakage of experimental sealer II did not differ significantly from leakage of AH Plus, Ketac-Endo and Sealapex. Due to the low leakage of experimental sealer II in the present study, further evaluations such as bacterial penetration or fluid filtration should follow.

Analysis of shrinkage of different gutta-percha types using optical measurement methods.

The aim of this study was to compare the shrinkage of alpha- and beta-gutta-percha of the Multifill-system with commercial gutta-percha. Ten gutta-percha blocks of each of the three types were used. Speckle pattern shearing interferometry was used to prove that no trapped air and material defects were present in the specimens. The optical triangulation method was applied to assess shrinkage. The three gutta-percha types were examined after heating up to 90 degrees C and cooling down to 35 degrees C. Commercial gutta-percha showed less shrinkage (6.5%) than alpha- (7.2%) and beta-gutta-percha (7.3%; p=0.0051 for both comparisons; Wilcoxon's signed rank test). There was a significant difference between alpha- and beta-gutta-percha (p=0.0093; Wilcoxon's signed rank test). In the range of 45 degrees C to 40 degrees C, alpha- and beta-gutta-percha revealed the highest shrinkage (2.2%/5 degrees C and 2.1%/5 degrees C, respectively). Commercial gutta-percha showed the highest shrinkage (1.1%/5 degrees C) in the range of 55 degrees C to 40 degrees C. Overall, shrinkage of all types of gutta-percha was higher than could be assumed from former studies.

[Bond strength of different resin composites to fiber-reinforced posts]. / Verbundfestigkeiten verschiedener Aufbaukomposite zu faserver-stärkten Wurzelkanalstiften.

Endodontically treated teeth often have little coronal tooth tissue remaining and as such require a post to retain the core and the restoration. Therefore, tooth coloured adhesive inserted fiber posts in combination with resin based core material can be used. In this study, the tensile bond strength of core materials to fiber posts was investigated. Three different core materials, Clearfil Core, CoreRestore 2 and MultiCore Flow in combination with two different fiber posts systems, ER DentinPost and DT Light Post, were tested. The posts were shortened to the lengths of 15 mm. The specimens were obtained while the upper part (3 mm) of the posts was covered with standardized cylinders of the core materials. Clearfil Core in combination with the DT Light Post (230.5 N +/- 42.2 N) and ER DentinPost (154. N +/- 33.6 N) had the highest tensile bond strengths of all groups. The tensile bond strength of CoreRestore 2 to DT Light Post (149.9 N +/- 29.5 N) was higher than the tensile bond strengths of the combinations MultiCore Flow/DT Light Post (140.9 N +/- 31.4 N) and Multi- Core Flow/ER DentinPost (122,. N +/-19,. N). The group Core-Restore 2TER DentinPost had the lowest tensile bond strengths (80,1 N ++/-19,4 N). The adhesion of the resin based core materials to the fiber posts is influenced by the post design and core materials. The combination of core materials with the type of fiber post has a great influence on the tensile bond strength.

[Retention of fiber posts dependent on different resin cements]. / Retention glasfaserverstärkter Wurzelkanalstifte in Abhängigkeit vom Befestigungskomposit.

Tooth-coloured adhesive inserted fiber posts are used to restore endodontically treated teeth. In this investigation, the tensile bond strength of two different fiber posts systems (ER DentinPost and DT Light Post) in combination with five different resin cements was tested. The posts were inserted into artificial root canals in bovine dentin using Clearfil Core, RelyX Unicem, Panavia 21ex, Panavia F2.0 und Calibra. Titan posts (ER-Kopfstift), inserted with zincphosphate cement served as control group. ER DentinPost inserted with Clearfil Core had significantly higher tensile bond strengths than in combination with Panavia F2.0 (221.70 +/- 17.99 N) or Calibra (212.37 +/- 45.20 N). DT Light Post in combination with Calibra (338.20 +/- 46.40 N), Panavia F2.0 (321.69 +/- 40.11 N) and Panavia 21ex (290.41 +/- 55.28 N) showed significantly higher tensile bond strengths compared to adhesive cementation with RelyX Unicem (211.57 +/- 32.35 N) and Clearfil Core (131.67 +/- 51.72 N). The tensile bond strength of the control group was in the upper third of the values (315.43 +/- 51.38 N). Optical analysis of the post surface after decementation demonstrated in all cases adhesive-cohesive mixed fractures. The adhesion of resin cement to the fiber posts and resin cement to root canal dentin is influenced by different factors. The combination of fiber post systems with the type of resin cement has a great influence on the tensile bond strength.

New bacterial compositions in root-filled teeth with periradicular lesions.

The aim of this study was to isolate and detect microorganisms of root-filled teeth associated with periradicular lesions. Specimens were sampled from patients undergoing root canal retreatment. The bacteria were characterized by morphologic and biochemical analysis and by 16S rRNA gene sequencing. Microorganisms were detected in 10 of 18 teeth. The majority of positive samples revealed a mixed culture of 2-8 species. In 2 teeth Enterococcus faecalis was the only detected species. For the first time Vagococcus fluvialis was detected in root canals. Solobacterium moorei and Fusobacterium nucleatum were the most prevalent species. Presence of F. nucleatum was associated with the presence of S. moorei in 5 of 7 cases. In all teeth with Parvimonas micra and Dialister invisus, F. nucleatum and S. moorei were found. Moreover, members of additional different genera were detected delivering bacterial compositions that have been not described yet.

Characterization of the first oral vagococcus isolate from a root-filled tooth with periradicular lesions.

Strain Endo-EH was isolated from a root-filled tooth associated with periradicular lesions. After subculturing on Columbia blood agar, phenotypic and genomic characterizations using different biochemical test systems, automated ribotyping, MALDI-TOF mass spectronomy, antibiotic susceptibility testing, and 16S rRNA gene sequence analysis were applied for further analysis. Phenotypic characterization identified this strain as Vagococcus fluvialis. Riboprint pattern analysis and 16S rRNA sequencing clearly separated it from relevant genera such as Enterococcus and Tetragenococcus and also from other Vagococcus species. This taxon is a new entry to the list of more than 200 microbial species detected in infected root canal systems.

Effectiveness of a hand file and three nickel-titanium rotary instruments for removing gutta-percha in curved root canals during retreatment.

OBJECTIVE: This study intended to compare the effectiveness of hand files and FlexMaster, ProTaper, and RaCe rotary instruments for removing gutta-percha in curved root canals during retreatment. STUDY DESIGN: Sixty curved mandibular premolars were randomly divided into 4 groups of 15 specimens each. The canals were enlarged and obturated using lateral condensation technique. After repreparation with the test instruments the specimens were cleared. The area of remaining obturation material was measured from 2 directions. Statistical analysis was performed using the Kruskal-Wallis test and a closed test procedure. RESULTS: RaCe instruments revealed significantly less residual obturation material than FlexMaster files (P < .05). No significant difference was found among the hand file, ProTaper, and FlexMaster groups (P > .05). There were 5 fractured instruments in the ProTaper group and 3 in the FlexMaster group. CONCLUSION: The RaCe system is an efficient and safe device for gutta-percha removal in curved root canals.

Shaping ability and safety of five different rotary nickel-titanium instruments compared with stainless steel hand instrumentation in simulated curved root canals.

OBJECTIVE: To compare the shaping ability and safety of engine-driven FlexMaster, GT Rotary, ProFile, ProTaper, and RaCe rotary instrumentation and Hedström hand instrumentation in simulated root canals. STUDY DESIGN: One hundred fifty simulated colored root canals with a curvature of 20 degrees and a radius of 10 mm were randomly distributed among 6 groups of 25 specimens each. After preparation to apical size 30 the area of remaining color on the canal wall indicating unprepared areas was measured in mm2 using image analyzer software. RESULTS: Specimens treated with RaCe left least areas of remaining color compared to all other groups (P < .001), followed by ProTaper. Preparation with ProFile left behind the highest amount of unprepared areas. The ProFile group revealed significantly more remaining color than ProTaper, GT Rotary, and FlexMaster (P < .05). Four FlexMaster files separated. CONCLUSION: RaCe rotary files were safe and more effective compared to the other instruments.