Anja Baraba

Antimicrobial efficacy of a high-power diode laser, photo-activated disinfection, conventional and sonic activated irrigation during root canal treatment

AIM To evaluate the antimicrobial effect of a diode laser irradiation, photo-activated disinfection (PAD), conventional and sonic activated irrigation with 2.5% sodium hypochlorite (NaOCl) on Enterococcus faecalis. METHODOLOGY Root canals of 120 human extracted teeth with single straight canals were prepared with ProTaper files, sterilized, contaminated with an E. faecalis suspension and incubated for 7 days. They were then randomly distributed into six groups: G1, diode laser irradiation (2 W, 3 × 20 s); G2, PAD (100 mW, 60 s); G3, PAD with 3D Endoprobe (100 mW, 60 s); G4, 30-gauge syringe irrigation with NaOCl (60 s); G5, sonic agitation of NaOCl with the EndoActivator system (60 s); G6, 30-gauge syringe irrigation with NaCl (60 s). The pattern of colonization was visualized by scanning electron microscopy. The root canals were sampled by flushing with saline solution at baseline and after the treatments. The number of bacteria in each canal was determined by plate count. The presence and the absence of E. faecalis in root canals were also demonstrated by polymerase chain reaction (PCR). RESULTS There was a significant reduction in the bacterial population after all treatments (P < 0.001). The PAD, using both laser systems, and the sonic activated NaOCl irrigation were significantly more effective than diode irradiation and single NaOCl irrigation in reducing CFUs (P < 0.05). High-power diode laser and single NaOCl irrigation had an equal antibacterial effect (P > 0.05). CONCLUSIONS The PAD and EndoActivator system were more successful in reducing the root canal infection than the diode laser and NaOCl syringe irrigation alone.

Active versus passive microleakage of Resilon/Epiphany and gutta-percha/AH Plus

The purpose of this in vitro study was to assess the active versus passive dye microleakage and apical sealing ability of laterally condensed gutta-percha/AH Plus versus Resilon/Epiphany. One hundred and twenty teeth were instrumented and divided into experimental, positive and negative control groups. In group 1, the teeth were obturated with gutta-percha/AH Plus and in group 2 the teeth were obturated with Resilon/Epiphany. The apical seal was evaluated with a passive and active dye penetration test. Absorbance of the extracted dye was determined with a spectrophotometer. Resilon/Epiphany showed less dye penetration in comparison with the gutta-percha/AH Plus group (P < 0.05). There were no statistically significant differences between the passive and active dye penetration tests (P > 0.05). In this in vitro study, canals obturated with Resilon/Epiphany showed less apical leakage than those obturated with gutta-percha/AH Plus, regardless of the type of dye penetration test used.

Ablative potential of the erbium-doped yttrium aluminium garnet laser and conventional handpieces: a comparative study.

OBJECTIVES To compare the ability of the Variable Square Pulse technology (VSP-technology)-based erbium-doped yttrium aluminium garnet (Er:YAG) laser working in maximum speed (MAX) mode (1000 mJ, 300 micros, 20 Hz) and the high-speed handpiece to ablate enamel, to compare the ability of for the VSP-technology-based Er:YAG laser working in MAX mode and the low-speed handpiece to ablate dentin, and to analyze in vitro effects of Er:YAG ablation of enamel and dentine surfaces using scanning electron microscopy (SEM). BACKGROUND DATA A VSP-technology-based Er:YAG laser operating in MAX mode should be appropriate for achieving the maximum ablating speed in hard dental tissues. MATERIALS AND METHODS The experiment was conducted on extracted, cleaned, sterilized human molar teeth. Cavity preparations were made in hard dental tissues using the VSP-technology Er:YAG laser in MAX mode, in enamel using the high-speed handpiece, and in dentin using the low-speed handpiece at different time intervals. A laser triangulation profilometer was used to determine cavity volumes. The cavity surfaces of five specimens were examined using SEM. RESULTS The Er:YAG laser removed a volume of enamel that was 3.3 times as large as that removed by the high-speed handpiece in the same period of time. In dentin, the Er:YAG laser removed 8 to 18 times as much volume as the steel bur in the same period of time. The Er:YAG ablation rate in dentin was faster than in enamel. SEM of laser prepared cavities showed a well-defined surface, free of the smear layer. CONCLUSIONS The VSP-technology-based Er:YAG laser, working in MAX mode, is more efficient than mechanical drills for enamel and dentin ablation.

Influence of Different Pulse Durations of Er:YAG Laser Based on Variable Square Pulse Technology on Microtensile Bond Strength of a Self-Etch Adhesive to Dentin

OBJECTIVE The aim of the study was to evaluate the microtensile bond strength of a composite resin to dentin modified with three different pulse durations of the Er:YAG laser based on variable square pulse technology and with one self-etch adhesive. MATERIALS AND METHODS The entire occlusal enamel was removed to obtain flat dentin surface for 48 human molar teeth. The teeth were randomly divided into four experimental groups (n=12 per group), according to the pretreatment of dentin: (1) control group; (2) super short pulse (SSP) (50 μsec); (3) medium short pulse (MSP) (100 μsec); and (4) short pulse (SP) (300 μsec) with Er:YAG laser. The energy of the laser used was 80 mJ with average power of 0.8 W. The microtensile bond strength was tested with a universal testing machine. Two specimens from each experimental group were subjected to scanning electron microscopic (SEM) examination, to observe the irradiated surface. RESULTS Dentin surface treated with SSP showed significantly lower microtensile bond strength values (24±9.8 MPa) in comparison with the control group and SP group (35.3±12.8 and 32.9±10.7 MPa, respectively), (p<0.05). The MSP and SP groups did not show any statistically significant difference in microtensile bond strength in comparsion with the control group (p>0.05). CONCLUSIONS The use of SP and MSP of the Er:YAG laser with one step self-etch adhesive does not impair or improve the microtensile bond strength in dentin, whereas SSP may not be suitable for dentin surface treatment prior to bonding procedures.

Evaluation of cytotoxic and genotoxic effects of two resin-based root-canal sealers and their components on human leucocytes in vitro

AIM To evaluate the in vitro genotoxicity and cytotoxicity of two resin-based root canal sealers and to determine the type of cell death they induce. METHODOLOGY The sealers tested were Epiphany and RealSeal. Each component of the material (Epiphany Primer, Epiphany Thinning Resin, Epiphany Sealant, RealSeal Primer, RealSeal Thinning Resin and RealSeal Root Canal Sealant), components in permutual combinations and all components mixed together were tested on human peripheral blood leucocytes using ethidium bromide/acridine orange viability staining and comet assay. Simultaneously, untreated negative control cultures were analysed in the same manner. DNA damage was evaluated following 4 h of treatment and after 24 h in the absence of the components of the materials. RESULTS After 4 h of treatment, except thinning resin, each individual component and the different combinations of components induced a significant increase in DNA migration ability (P < 0.05). After 24 h, combination of primer, thinning resin and sealant of both materials caused cell death inducing intense apoptosis. After 24 h, cells exposed to Epiphany Sealant and RealSeal Root Canal Sealant, both in polymerized and unpolymerized form, exhibited a level of DNA damage that was similar to the control. CONCLUSIONS Primer and thinning resin of both resin-based root canal sealers and their combinations were cytotoxic and induced apoptosis. Both sealants had no significant effect on the viability of the human leucocytes.

Ablative Potential of Four Different Pulses of Er:YAG Lasers and Low-Speed Hand Piece

OBJECTIVE The aim of the study was to evaluate the ablation rate of caries in dentin with fluorescence-feedback controlled Er:YAG, Variable Square Pulse technology (VSPt) based Er:YAG working in different pulse durations, and steel bur. MATERIALS AND METHODS Sixty human molar teeth with caries in dentin, extracted for periodontal reasons, were selected for this study. All selected teeth were randomly divided into five groups, each containing twelve specimens: (1) group FFC, fluorescence feedback-controlled Er:YAG laser; (2) group SSP (super short pulse: 50 μs); (3) group MSP (medium short pulse; 100 μs); (4) group SP (short pulse; 300 μs); and (5) group SB, steel bur in a slow-speed hand piece. A profilometer was used to determine the volume of the ablated caries in dentin. The clinical and real ablation rates of caries in dentin were calculated. Two specimens from each experimental group were selected randomly and subjected to SEM examination. RESULTS The volumes of the ablated caries in dentin in the SSP and SB groups were statistically significantly different in comparison with other experimental groups (p<0.05). The clinical and real ablation rate of caries in dentin was the highest for the SSP group (0.15±0.05 and 0.17±0.05 mm(3)/sec, respectively) and statistically significantly different in comparison with the MSP and SB groups (p<0.05). The SB and FFC groups revealed a dentin surface with a smear layer and closed dentinal tubules on SEM micrographs. In the SSP, MSP, and SP groups, an irregular surface without a smear layer was found. CONCLUSIONS Taking into consideration the experimental conditions of the present study, SSP was the most efficient in ablation of caries in dentin, providing a smear layer-free surface with open dentinal tubules.

Effect of photon induced photoacoustic streaming (PIPS) on bond strength to dentine of two root canal filling materials.

The aim of this study was to evaluate the effect of photon induced photoacoustic streaming (PIPS) technique in combination with EDTA on bond strength of gutta‐percha/AH Plus and Resilon/RealSeal SE root canal fillings to root dentine.

Cytotoxicity of Two Bioactive Root Canal Sealers.

OBJECTIVE The aim of this study was to investigate the cytotoxicity of two different bioactive root canal sealers: one based on mineral trioxide aggregate, MTA Fillapex (Angelus, Solucoes Odontologicas, Londrina, PR, Brazil), and the other based on bioceramics, Endosequence BC Sealer (Brasseler, Savannah, Georgia, USA), in culture of mouse L929 fibroblasts. MATERIALS AND METHODS Mouse fibroblasts (L929), obtained from subcutaneous connective tissue of mouse line C3Hf, were cultivated in plastic culture flasks in an incubator at 37şC, with 5% CO2 and 90% humidity. Freshly mixed Endosequence BC Sealer and MTA Fillapex (0.1 g each) were placed on sterile teflon discs, 6 mm in diameter. Teflon discs with the materials as well as empty discs serving as control were placed in wells of 12-well plate. After incubation times of 1, 6, 20 and 24 hours, the teflon discs were removed from the wells and the number of viable cells was determined using trypan blue in Neubauer chamber. RESULTS In comparison to the control group, MTA Fillapex had significantly less viable cells for all incubation periods (p≤0.05), while Endosequence BC sealer had significantly less viable cells after 6, 20, and 24 hours of incubation (p≤0.05). MTA Fillapex comprised significantly less viable cells in comparison to Endosequence BC sealer after the first hour and after 20 hours of incubation (p≤0.05), while for the other incubation periods there were no significant differences (p≥0.05). CONCLUSION MTA Fillapex and Endosequence BC sealer were both cytotoxic in cultures of mouse L929 fibroblasts.

Utjecaj ispiranja aktiviranog erbijskim laserima na čvrstoću vezivanja individualnog kompozitnog kolčića ojačanog vlaknima na dentin korijenskog kanala

OBJECTIVE The aim of this in vitro study was to investigate the effect of laser activated irrigation (LAI) using two erbium lasers on bond strength of individually formed fiber-reinforced composite (FRC) posts to root canal dentin. MATERIALS AND METHODS Twenty-seven single-rooted human teeth were endodontically treated and after post space preparation divided into three groups (n=9 per group), according to the pre-treatment of post space preparation: 1) Conventional syringe irrigation (CSI) and saline; 2) Er.YAG photon-induced photoacoustic streaming (PIPS) technique and saline; 3) Er,Cr:YSGG activated irrigation with RFT2 tip. Two specimens from each group were used for SEM analysis. The remaining specimens (n=7 per group) received individually formed FRC post, everStick POST, luted with self-adhesive cement, G-CEM LinkAce. After cementation, the roots were perpendicularly sectioned into 1 mm thin sections and a push-out test was carried out (0.5 mm/min). The data were calculated as megapascals and were log transformed and statistically analysed using one-way ANOVA at the level of significance set at 5%. RESULTS In the control group, the smear layer was still present. In the Er:YAG group, the smear layer was removed. In the Er,Cr:YSGG group, the smear layer was partially removed. The Er,Cr:YSGG group achieved the highest bond strength values, followed by the control group and then the Er:YAG group, but no statistically significant difference was found in bond strength values in the tested group of post space pretreatment (p=0.564). CONCLUSIONS LAI using two erbium lasers, with PIPS or RFT2 tip, did not affect the bond strength of individually formed FRC posts to root canal dentin.

In vitro retention of prefabricated and individually formed posts: A pilot study

Statement of problem. Data on the retention of individually formed fiber‐reinforced composite posts (everStick) cemented with self‐adhesive cement are lacking. Purpose. The purpose of this in vitro study was to investigate the pull‐out strength of 2 different fiber‐reinforced composite posts (prefabricated and individually formed) cemented into extracted teeth with self‐adhesive resin cement. Material and methods. Thirty extracted single‐rooted human teeth were decoronated, endodontically treated, and prepared with post spaces of equal length. Prepared specimens were divided into 2 groups (n=15 each) based on the type of post: commercially prefabricated fiber posts (GC) and individually formed resin posts (using GC reinforcing fibers). Self‐adhesive resin cement (G‐CEM LinkAce; GC) was used to cement all posts. Each post was held with moderate pressure, and root surfaces were light polymerized for 20 seconds (650 mW/cm2). After cementation, the specimens were stored in saline solution for 30 days. Treated teeth were kept in water for 24 hours before pull‐out testing parallel to the longitudinal axis of the posts. Data were analyzed using the Student t test (&agr;=.05) and the coefficient of variance as the ratio of the standard deviation to the mean. Results. The mean pull‐out retention strength was 185.7 ±61.2 N for the prefabricated fiber posts and 98.9 ±56.5 N for the individually formed fiber posts (P=.026). Conclusions. The prefabricated fiber posts exhibited significantly higher retention forces than the individually formed posts.