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OTHER ONLINE ARTICLES


Prosthodontics

  • Evidence-based concepts and procedures for bonded inlays and onlays. Part III. A case series with long-term clinical results and follow-up

    Evidence-based concepts and procedures for bonded inlays and onlays. Part III. A case series with long-term clinical results and follow-up

    This third article in this series (Part III) aims to presentnew clinical results and long-term follow-up of resin composite inlays andonlays using the modern clinical concepts presented in the Part I and Part IIarticles. These revised protocols have contributed to eliminating the mostfrequent difficulties related to the preparation, isolation, impression taking,and cementation of tooth-colored inlays and onlays. This clinical reportpresents a series of 25 cases of indirect or semidirect inlays and onlays (intra-and extraoral techniques) made of microhybrid and nanohybrid composites with 6-to 21-year follow-ups. The restoration performance was assessed throughclinical examination, intraoral radiographs, and clinical photographs. Theoverall clinical assessment aimed to confirm the absence (success) or presence(failure) of decay or restoration fracture, while the restoration quality was judgedon intraoral photographs. The restoration status with regard to margins,anatomy, and color was assessed using three quality scores (A = ideal, B =satisfactory, C = insufficient). Descriptive statistics were used to evaluatethe possible impact of composite structure (microhybrid or nanohybrid) orobservation time on restoration quality. Over this medium- to long-termobservation period, no clinical failure was reported. Only a few restorations (mainlythose made of conventional inhomogeneous nanohybrid) presented discretemarginal discoloration (n = 4) or occlusal anatomy change due to wear (n = 7).This first clinical survey with long-term follow-up supports the application ofthe aforementioned clinical concepts, which thus far have only been validatedby in vitro studies.


    Didier Dietschi / Roberto Spreafico

ENDODONTICS

  • An update on ultrasonic irrigant activation

    An update on ultrasonic irrigant activation

    Ultrasonicirrigant activation is the most widely used supplementary irrigation method. Itrelies on the oscillation of an instrument at ultrasonic frequency whilesurrounded by irrigant, which results in heating of the irrigant, intensestreaming and, under certain conditions, cavitation. A variety of ultrasonicfiles, tips, wires and needles have been used for this purpose. The efficacy ofultrasonic activation depends on the size of the instrument, the power settingand the direction of oscillation. Sodium hypochlorite,ethylenediaminetetraacetic acid (EDTA) and chlorhexidine are the most commonlyactivated irrigants and they can be delivered either simultaneously or between activationperiods. This method appears very effective in the removal of pulp tissueremnants and hard tissue debris from the root canal. However, there isconflicting information regarding its antimicrobial effect and there seems tobe no improvement in the treatment success rate, at least in single-rootedteeth. Instrument-to-wall contact appears inevitable under clinical conditionsand may result in oscillation dampening and removal of small amounts ofdentine. Ultrasonic instruments may fracture during use because of fatigue.Irrigant extrusion through the apical foramen is very limited except when theirrigant is continuously delivered and activated by an ultrasonic needle.Electromagnetic interference with pacemakers is unlikely to occur. Importantknowledge gaps still exist, so ultrasonic activation is a topic of interest forfuture studies.


    Anastasios Retsas, Christos Boutsioukis
  • Effect of Sterilization on Bond Strength and Mechanical Properties of Fiber Posts

    Effect of Sterilization on Bond Strength and Mechanical Properties of Fiber Posts

    Purpose: Todetermine the effects of two different sterilization methods on the pull-outbond strength, flexural strength, and elastic modulus of glass-fiber posts. Materialsand Methods: A total of 69 glass-fiber posts were used. The postswere divided into three groups according to applied sterilization method: 1)control, 2) ethylene oxide gas (EOG), and 3) autoclave. The microstructure ofthree posts from each group was evaluated by SEM and energy-dispersive X-rayspectroscopy (EDS). Thirty glass-fiber posts were used to evaluate pull-outbond strength. The three-point bending test was performed to analyze theflexural strength on another 30 glass-fiber posts. Failure modes werecategorized microscopically after the pull-out test. After the three-pointbending test, micromorphology at the bending area was examined using SEM. Results:One-way ANOVA indicated no statistically significant differences amongthe group means in terms of bond strength (p > 0.05), flexural strength (p> 0.05), or elastic modulus (p > 0.05). EDS revealed that the weightpercentage of surface oxygen atoms in the EOG- and autoclave-sterilizationgroups were significantly higher. SEM images were similar. Conclusion:The results of this study show that glass-fiber posts can besterilized either by autoclave or EOG when necessary, without any negativeeffect on bond strength, flexural strength, or elastic modulus.


    Filiz Yagci / Yakup Ustun / Mustafa Zortuk / Mehmet Agirnasligil

PERIODONTICS

  • The Biologic Effect of Particulate Titanium Contaminants of Dental Implants on Human Osteoblasts and Gingival Fibroblasts

    The Biologic Effect of Particulate Titanium Contaminants of Dental Implants on Human Osteoblasts and Gingival Fibroblasts

    Purpose: To evaluatethe effects of different titanium particle concentrations on the viability ofhuman calvarial osteoblasts and human gingival fibroblasts. Materials and Methods: Primary humancalvarial osteoblasts (HCO, 3H Biomedical) and human gingival fibroblasts(HGF-1, ATCC) were cultivated and allowed to adhere for 24 hours. Titaniumpowder concentrations (0.01 to 1.0 mg/mL) were added, and samples were analyzedat three time points (24 hours, 7 days, 21 days). Cell viability was analyzedusing living cell count, proliferation (MTT) assay, and live/dead staining.Cytotoxic effects were evaluated using lactated dehydrogenase assay. Qualitativeanalysis of cell viability was performed. In addition, scanning electronmicroscopy (SEM) analysis was performed. Release of interleukin 6 (IL-6) andtumor necrosis factor alpha (TNF-a) was estimated with humanIL-6/human TNF-a ELISA. Results: Titanium concentrations of 0.1mg/mL and 1.0 mg/mL showed medium- and long-term effects on cell growth andproliferation rates. Cytotoxic effects by release of lactate dehydrogenase wereobservable during the first 24 hours. Human gingival fibroblast cells showed arelease factor between 2.6 and 3.4. Titanium powder seemed to be more cytotoxicto human gingival fibroblast cells than to human calvarial osteoblast cells.For human calvarial osteoblasts, only the highest concentration showedcytotoxic effects with a release factor of 2.7. Human calvarial osteoblasts secretedIL-6 only during the first 24 hours and only in the highest titaniumconcentration, whereas human gingival fibroblasts secreted IL-6 during theentire period. The lowest titanium concentration showed stronger secretion ofIL-6 compared with the control. Incorporation of smaller and single titaniumparticles by cells was identified under SEM analysis. Conclusion:Cell viability is negatively correlated with titanium concentration.Further, titanium debris might lead to an inflammatory biologic response ofdental peri-implant tissue. Also, cells interact with the debris, eg, withincorporation of particles.


    Arndt Happe / Sonja Sielker / Marcel Hanisch / Susanne Jung