Effectiveness of laser-assisted irrigation and passive ultrasonic irrigation techniques on smear layer removal in middle and apical thirds.

The purpose of this study was to investigate the evaluation of laser-assisted irrigation (LAI) on the removal of the smear layer as compared to passive ultrasonic irrigation (PUI). Forty-eight single-rooted, upper-central incisor teeth were selected and prepared with ProTaper rotary instruments up to size #40 (F4) at the working lengths. Specimens were divided into four groups, as follows: (a) PUI with 5 mL of 2.5% NaOCl for 60 s; (b) PUI with 2.5 mL of 17% EDTA and 2.5 mL of 2.5% NaOCl each for 30 s; (c) LAI with 5 mL of 2.5% NaOCl for 60 s; and (d) LAI with 2.5 mL of 17% EDTA and 2.5 mL of 2.5% NaOCl each for 30 s. In the PUI groups, the ultrasonically activated file was inserted 1 mm short of the working length, but in the LAI groups, the fiber tip was applied into the pulp chamber. LAI in the pulp chamber with the combination of 17% EDTA and 2.5% NaOCl removed more of the smear layer than the other groups (p < 0.018). LAI in the pulp chamber with the combination of 2.5% NaOCl and 17% EDTA better removed the smear layer than LAI applied similarly but without EDTA or PUI with the same NaOCl and EDTA combinations using an ultrasonically activated file inserted 1 mm short of the working length.

Effectiveness of ProTaper Universal retreatment instruments used with rotary or reciprocating adaptive motion in the removal of root canal filling material.

AIM: To compare the effectiveness of ProTaper Universal retreatment instruments with continuous rotation and adaptive motion (AM; a modified reciprocating motion that combines rotational and reciprocating motion) in the removal of filling material. METHODOLOGY: Mesiobuccal root canals in 36 mandibular first molars were instrumented up to size F2 with the ProTaper Universal instrument (Dentsply Maillefer, Ballaigues, Switzerland) and filled using sealer and ProTaper Universal F2 gutta-percha cones. Gutta-percha was then down-packed and the root canal backfilled using the extruder hand-piece of the Elements Obturation System (SybronEndo, Orange, CA, USA). The teeth were assigned to two groups (n = 18), and removal of the root fillings was performed using one of the following techniques: group 1) ProTaper Universal retreatment files used with rotational motion (RM) and group 2) ProTaper Universal retreatment files used with adaptive motion (AM) (600° clockwise/0° counter-clockwise to 370° clockwise/50° counter-clockwise). The teeth were sectioned, and both halves were analysed at 8 × magnification. The percentage of remaining filling material was recorded. The data were analysed statistically using the Student's t-test at a 95% confidence level (P < 0.05). RESULTS: There was no significant difference between the groups with respect to the total time required for retreatment (P = 0.481). The AM technique left significantly less filling material than the RM method (P = 0.013). CONCLUSION: The use of ProTaper Universal retreatment files with adaptive motion removed more filling materials from root canals than the rotational movement.

An in vitro comparison of irrigation using photon-initiated photoacoustic streaming, ultrasonic, sonic and needle techniques in removing calcium hydroxide.

AIM: To evaluate the effect of various techniques including photon-initiated photoacoustic streaming (PIPS), ultrasonic, sonic and needle irrigation on the removal of calcium hydroxide [Ca(OH)2 ] from artificial grooves created in root canals. METHODS: The root canals of 48 extracted single-rooted teeth with straight canals were prepared using ProTaper rotary instruments up to size 40. After the specimens had been split longitudinally, a standardized groove was prepared in the apical part of one segment that was filled with Ca(OH)2 powder mixed with distilled water. Each tooth was reassembled and the apices closed with wax. The specimens were irrigated for 60 s with one of the following techniques: needle irrigation using 17% EDTA, PIPS with 17% EDTA, ultrasonic irrigation using 17% EDTA and sonic irrigation (EndoActivator) using 17% EDTA. The root segments were then disassembled, and the amount of remaining Ca(OH)2 evaluated under a stereomicroscope at 25× magnification. A pixel count of Ca(OH)2 remaining on the artificially created grooves was recorded as a percentage of the overall groove surface. The data were evaluated statistically using one-way analysis of variance and the least significant difference post hoc tests at 95% confidence level (P = 0.05). RESULTS: Photon-initiated photoacoustic streaming was superior in removing Ca(OH)2 as compared to needle irrigation (P < 0.001), sonic irrigation (P < 0.001) and ultrasonic irrigation (P = 0.046). CONCLUSION: Photon-initiated photoacoustic streaming provided complete removal of Ca(OH)2 from artificial grooves in straight root canals. Ultrasonic irrigation enhanced the Ca(OH)2 removal capacity of irrigating solution but did not provide complete removal from artificial grooves.

Effect of photon-initiated photoacoustic streaming on removal of apically placed dentinal debris.

AIM: To compare the efficacy of photon-induced photoacoustic streaming (PIPS) technique with conventional, sonic and ultrasonic irrigation on the removal of apically placed dentinal debris from an artificial groove created in a root canal. METHODOLOGY: Root canal preparation was performed up to size 40 on 48 extracted single-rooted teeth using ProTaper rotary instruments. The specimens were then split longitudinally, and a standardized groove was prepared in the apical part of each segment. Each groove was filled with dentinal debris mixed with 5% NaOCl. Each tooth was reassembled and irrigated as follows: (i) conventional irrigation with 1% NaOCl, (ii) sonic, (iii) ultrasonic irrigation, and (iv) PIPS. The root segments were disassembled, and the amount of remaining dentinal debris was evaluated under a stereomicroscope at 20× magnification, using a four-grade scoring system. The data were evaluated statistically using Kruskal-Wallis and Mann-Whitney U-tests with a 95% confidence level (P = 0.05). RESULTS: Photon-induced photoacoustic streaming removed significantly more dentinal debris than conventional irrigation (P < 0.001), sonic irrigation (P < 0.001) or ultrasonic irrigation (P = 0.005). There was no significant difference between sonic and ultrasonic irrigation (P = 0.377). CONCLUSIONS: Photon-induced photoacoustic streaming was more effective than conventional, sonic and ultrasonic irrigation in the removal of apically placed dentinal debris.

Efficacy of various irrigation protocols on the removal of triple antibiotic paste.

AIM: To compare the efficacy of irrigation protocols on the removal of triple antibiotic paste (metronidazole, ciprofloxacin and minocycline) (TAP) from artificial grooves in root canals. METHODOLOGY: Root canals in 72 extracted single-rooted teeth were prepared using ProTaper rotary instruments up to size F5. The roots were split longitudinally and a standardized groove was prepared in the apical part of one segment. TAP was placed in the grooves, and the root halves were reassembled. The roots were randomly divided into six experimental groups according to the irrigation protocol used: distilled water, 1% NaOCl, 2.5% NaOCl, 100% ethanol, 17% EDTA and passive ultrasonic irrigation (PUI) with 1% NaOCl. The root segments were disassembled, and the amount of TAP remaining was evaluated under a stereomicroscope at 20× magnification using a four-grade scoring system. The data were evaluated statistically using Kruskal-Wallis and Mann-Whitney U-tests with a 95% confidence level (P = 0.05). RESULTS: There were significant differences amongst the groups (P < 0.001). Passive ultrasonic irrigation (PUI) with 1% NaOCl removed significantly more TAP than the other irrigating solutions (P < 0.05). Distilled water, 1% NaOCl, ethanol and EDTA were associated with significantly more remaining TAP. CONCLUSIONS: PUI with 1% NaOCl was more effective in removing TAP from artificial grooves in root canals than other irrigating solutions without ultrasonic agitation. It was not possible completely to remove TAP from root canals.

Colour stability of porcelain repair materials with accelerated ageing.

The purpose of this study was to measure and compare the colour stability of three porcelain repair materials (Charizma, Clearfil and Silux Plus) with an all-ceramic material following accelerated ageing. Three composites and one ceramic control were subjected to accelerated ageing for a period of 300 h. Initial specimen colour parameters were determined in the Commission International de I'Eclairage Lab (CIELAB) colour order system with a colorimeter. Colour changes were calculated before (DeltaE) and after 300 h of accelerated ageing (DeltaE*). Colour difference data were subjected to one-way analysis of variance (anova) followed by Duncan's test to examine the interaction between material and time interval of ageing. There were no significant difference between DeltaL values of Porcelain-Charizma and Porcelain-Silux Plus. All mean DeltaL* values were negative after 300 h ageing. Porcelain-Silux Plus demonstrated the highest DeltaL* of the investigated groups. There were significant differences between baseline 300-h aged specimens with respect to Deltaa*, Deltaa for either of the investigated materials. For Silux Plus, Deltaa and Deltaa* values were significantly higher than the others. Significant differences were observed between baseline and 300-h values for Deltab and Deltab*. Deltab and Deltab* values were significantly higher for Silux Plus. There were significant differences between baseline and 300-h values of colour difference, DeltaE, DeltaE*. Highest DeltaE* value was obtained using the microfilled composite, Silux Plus. Lowest value of DeltaE was recorded with the hybrid composite, Charizma.

Corrosion susceptibility of titanium covered by dental cements.

Titanium has become a material of great interest in prosthodontics in recent years because of its excellent biocompatibility, corrosion resistance and desirable physical and mechanical properties. In this study, we determined the influence of dental cements on the passivation of titanium. We developed experimental electrodes that associate titanium and dental cements. Polarization resistance of titanium electrodes has been determined for uncovered metal and electrodes covered with five different dental cements. Coverage with zinc eugenate led to more resistance to corrosion, but fluorinated composite such as glass-ionomer and zinc phosphate coverage increased the corrosion susceptibility.

Effect of ceramic surface treatment on the shear bond strengths of two resin luting agents to all-ceramic materials.

The purpose of this study was to evaluate the bond strengths of some resin luting cements of two different all ceramic materials (In-Ceram, IPS-Empress). Composite cylinders 3.2 x 2 mm were prepared on the ceramic surfaces for a shear test. Four ceramic surface treatments were performed. (i). As received, (ii). grinding with diamond bur, (iii). sandblasting with 50 microm alumina grit and (iv). HF acid treatment and sandblasting with 50 microm alumina grit. Ceramic specimens were treated with one of the four methods and then cemented together with each of the two luting agents. The tested luting cements were Panavia F and Clearfil Se Bond (CSeB). The CSeB demonstrated the highest bond strength (59.95 MPa) regardless of the ceramic blocks. The average of load to fracture the In-Ceram blocks luted with Panavia F cement was 25.89 MPa. The mean shear bond strength of IPS Empress blocks luted with Panavia F cement was 10.31 MPa. Grinding the surface with a diamond bur for In-Ceram blocks luted with Panavia-F was 30.93 MPa and with CSeB was 77.04 MPa. For IPS-Empress blocks these values decreased to 12.39 MPa for Panavia-F and 30.84 MPa for CSeB. Acid etching of the surfaces with HF acid demonstrated a weak tendency to improve bond strength (In-Ceram-->Panavia-F= 14.59 MPa and CSeB=59.32 Mpa; IPS-Empress--> Panavia-F=5.85 MPa and CSeB= 23.33 MPa).

Compressive shear strength of core materials and restoring techniques.

In this study, ninety extracted endodontically treated mandibular molars were mounted in acrylic resin blocks. Five groups of eighteen extracted teeth were prepared by two different techniques. A peripheral shelf 2 mm deep and 1.4 mm wide was prepared as a first technique, while TMS pins were used in the second group. The teeth were then restored with five different core materials: silver-reinforced glass-ionomer, resin-modified glass-ionomer, self-cured glass-ionomer, polyacid-modified composite resin, and titanium-reinforced composite resin. An Instron testing machine was used to apply shear force at a crosshead speed of 2 mm/min until fracture occurred. The results were obtained statistically using analysis of variance and least significant difference tests. According to the results of this study, Ti-core and composite resin were the strongest core materials when subjected to shear forces, and the most retentive preparation design was the vertical-pin design. The fractures of these materials with a vertical-pin design were mostly seen at the core and the tooth.

Retentive forces of two magnetic systems compared with two precision attachments.

Magnetic retention devices based on cobalt/samarium alloy are new to dentistry, whereas precision attachments have been used for many years. In this study, the retentive forces of two magnetic systems were compared with two different precision attachment units. The retentive forces were evaluated with an Instron testing machine with a cross-head speed of 0.5 mm/min. Eight samples were used for each of the four attachments for a total of 32 samples. The attachments were embedded in an acrylic block and tested for initial retention and retention after 300 cycles. The retentive forces of the precision attachments were greater than the magnetic attachments for the initial retention. However, as more cycles were completed, the retentive force decreased in the precision attachments and increased in the magnetic attachments. The results were statistically significant among the four attachment systems (p = 0.0117).

Investigation of the effect of magnetic retention systems used in prostheses on buccal mucosal blood flow.

The purpose of this study was to investigate the probable effects of the magnetic field produced by dental magnets on neighboring capillary circulation. Ten subjects were used. Transparent acrylic resin devices were prepared to receive the dental magnets and were used continually by subjects except during sleep. The maxillary buccal mucosal blood flow was measured on both sides (control and experimental) in the same subjects before the use of dental magnets and after 3, 7, 15, 30, and 45 days by the 133Xe clearance technique. Upon analysis it was found that the difference in blood flow between the control and experimental sides was insignificant (P greater than .05). The decrease in blood flow as time progressed was attributed to the pressure exerted by the oral devices rather than by the effect of the magnetic field.

[The cytotoxic effects of composite resin adhesive agents on gingival cell culture using the agar coating method]. / Yapistirma ajani olarak kullanilan kompozit resinlerin sitotoksik etkilerinin agar-kat yöntemi ile gingiva hücre kültüründe incelenmesi.

Because the luting agent interfaces of restorations can approximate the periodontium, it is critical to determine the biocompatibility of luting agents. In this study, the cytotoxic potential of resin luting agents on cultures of gingival fibroblasts was evaluated for direct microscopic cytotoxicity. For light cured composite resin luting agents, the exposure time was found to be significant. To compare the chemically and light cured resins, fully cured microfill resin's cytotoxicity was equal to the chemically cured resin's cytotoxicity. The least cytotoxic effect was occurred with hybrid type composite resin while the profound effect with unpolymerized microfill resin.

[The effect of disinfectant substances on various silicon and irreversible hydrocolloid impression materials]. / Silikon ve irreversible hidrokolloid ölçü materyallerine çesitli dezenfektan maddelerin etkinligi.

Infection control in dentistry focuses on the prevention of cross-contamination among patients, dentists and dental personnel. Difficulties in sterilizing impression materials have led to chemical disinfection as an alternative. This study evaluated the efficacy of disinfectants on the surfaces of silicon and irreversible hydrocolloid materials involved microorganisms. All disinfectants used in this study was effective on Pseudomonas aeruginosa and Candida albicans for silicon impression material and Candida albicans for irreversible hydrocolloid.

[The effect of magnetic retainers used in dental prostheses on the pathogenic microorganisms in the oral flora]. / Dental protezlerde kullanilan magnetik tutucularin agiz florasindaki patojen mikroorganizmalara etkisi.

Patents for magnetic denture retainers in dental prosthesis, have issued since 1930, but recent developments rekindled interest. There have been many studies reporting the effects of magnetic fields on humans, animals, insects, tissue cultures, micro-organisms and enzymes. In some of these reports, damaging tissue effects were observed. In our study, the effect of these magnets to the growth of pathogen microorganisms found in oral flora were investigated with 2 different microbiological methods. In either of these methods, it was determined that the magnetic field didn't affect the colonization of bacteria.