Short fiber reinforced composite on fracture strength of immature permanent anterior teeth with simulated regenerative endodontic procedures: an in vitro study.

The aim of the present study was to evaluate the effect of short fiber reinforced composite on the fracture strength of anterior immature teeth treated with regenerative endodontic procedures. A total of 120 permanent maxillary central incisors were selected, and root lengths were standardized. Except for the positive control group (n = 20), the root canals were instrumented to simulate immature teeth with incomplete root development, and the regenerative endodontic procedure was performed. Twenty instrumented teeth acted as negative controls (n = 20), and the remaining 80 teeth were randomly divided into 4 groups according to the chosen coronal restoration material: bulk fill, short fiber reinforced composite (SFRC), polyethylene fiber (Ribbond Ultra), and flowable composite resin. Each specimen was then subjected to fracture testing using a universal testing machine (AGS-X, Shimadzu, Japan). The load to fracture was recorded. Data were subjected to statistical analysis using analysis of variance and the Tukey Honestly Significant Difference test. A significant difference was detected between the groups (p < 0.05), with the positive control group showing the highest mean fracture strength. The SFRC group had significantly higher values than the bulk fill, polyethylene fiber, flowable composite resin and negative control groups. In conclusion, SFRC has a relatively high fracture strength compared to other materials used in regenerative endodontic procedures. The use of SFRC enhanced the fracture strength of immature permanent teeth.

Effectiveness of the static-guided endodontic technique for accessing the root canal through MTA and its effect on fracture strength.

OBJECTIVES: (1) To evaluate the effectiveness of the static-guided (SG) endodontics technique for accessing the root canal through the mineral trioxide aggregate (MTA) and (2) to evaluate the effect of this technique on the fracture strength of teeth. MATERIALS AND METHODS: Thirty mandibular premolars were used in the present study. After standard coronal access cavity preparation, root canals were prepared up to size #80 to simulate an immature root apex. White MTA was placed approximately 3 mm below the cementoenamel junction (CEJ), as placed in regenerative endodontic procedures. After the MTA had set, the cavity was restored with a resin composite material. The teeth were randomly divided into two groups (n = 15). In the control group, the composite resin and MTA were removed without any guide. In the SG-access group, a cone beam computed tomography (CBCT) scan was performed, 3D-printed guides were designed and fabricated, and then the composite resin and MTA were removed with a guide. One inexperienced operator performed the removal of the composite resin and MTA in all groups. Pre- and post-operative periapical radiographs were taken. The mishaps and time to penetration to root canal were recorded. After that, the root canals were filled, and the access cavities were restored. The samples were subjected to a fracture strength test. Data were analyzed using Mann-Whitney U, independent samples of T test, and chi-square tests at 95% confidence level (P = 0.05). RESULTS: There were significant differences between the control and SG-access groups in terms of mishaps and time to penetration to the root canal through the MTA barrier (P < 0.05). The SG-access group required the shorter time as compared with the control group. Mishaps did not occur in the SG-access group. The SG-access group exhibited the significantly preserved fracture resistance of the teeth as compared with the control group (P < 0.05). Non-restorable failure occurred more frequently in the control group than in the SG-access group. CONCLUSIONS: Within the limitations of the present study, the SG endodontic technique yielded favorable results with respect to time, mishaps, and fracture strength. CLINICAL RELEVANCE: The static-guided endodontics technique may provide advantages to the clinician for MTA removal.

Effect of calcium hydroxide mixed with lidocaine hydrochloride on postoperative pain in teeth with irreversible pulpitis and symptomatic apical periodontitis: a preliminary randomized controlled prospective clinical trial.

OBJECTIVES: To investigate the effect of calcium hydroxide mixed with lidocaine HCl on postoperative spontaneous pain. MATERIALS AND METHODS: Sixty patients having irreversible pulpitis and symptomatic apical periodontitis with a preoperative spontaneous pain and percussion pain which was more than 50 on a visual analogue scale (100 mm VAS) were included in this study. After the preparation of the root canals, the patients were randomly distributed into two groups according to the calcium hydroxide vehicle, control group (mixed with saline) and calcium hydroxide mixed with lidocaine HCl (n = 30). Postoperative spontaneous pain scores were recorded by a VAS every day for a week. Data were analysed using one-way analysis of variance, chi-squared test and Mann-Whitney U tests (p = 0.05). RESULTS: The calcium hydroxide mixed with lidocaine HCl group resulted in significantly less pain compared with the calcium hydroxide mixed with saline group during days 1 to 4 (p < 0.05). There were no significant differences between the groups in terms of postoperative percussion pain levels (p > 0.05). CONCLUSION: Within the limitations of this study, it can be concluded that the calcium hydroxide mixed with lidocaine HCl can be beneficial in reducing postoperative pain in teeth with irreversible pulpitis and symptomatic apical periodontitis. CLINICAL RELEVANCE: The calcium hydroxide mixed with lidocaine HCl can be beneficial in reducing postoperative pain in teeth with irreversible pulpitis and symptomatic apical periodontitis. CLINICAL REGISTRATION NUMBER: TCTR20181121003.

Duration of ultrasonic activation causing secondary fractures during the removal of the separated instruments with different tapers.

OBJECTIVES: The aim of the present study was to determine the effect of taper (.08, .06, and .04) of separated K3XF instruments on duration taken for the secondary fracture formation during ultrasonic activation. MATERIALS AND METHODS: Ten 25/.08 K3XF (SybronEndo, Orange, CA, USA), ten 25/.06 K3XF, and ten 25/.04 K3XF instruments were used for the study. The apical 5 mm of the instruments was cut to simulate the fragments in root canals. Fragments of the instruments were sandwiched between two straight dentin blocks. An ultrasonic tip was used to cause a secondary fracture of the fragment. The time needed for the secondary fracture was recorded for each instrument. The data were statistically analyzed using the Kruskal-Wallis H test (alpha = 0.05). RESULTS: Secondary fractures occurred in all instruments. In the .08 taper group, secondary fractures took longer than in the case of the .06 and the .04 taper groups (P < 0.05). There were no significant differences between the .06 and the .04 taper groups in terms of the time required for the occurrence of a secondary fracture (P > 0.05). CONCLUSIONS: In the .08 taper group, secondary fracture took longer time than in the case of the .06 and the .04 taper groups due to its larger cross-sectional area involved. CLINICAL RELEVANCE: Typically, when removing separated instruments, a much lower power setting is chosen. The purpose of this in vitro study was to determine which tapered files were more resilient to secondary fracture, thus allowing a higher power setting to be chosen. Thus, the results of the present study cannot be used in clinical practice. If the clinician knows the taper of the broken file, the clinician should be very careful with regard to secondary fractures when using ultrasonics to remove the separated smaller tapered instruments.

The effect of photobiomodulation on total amount of substance P in gingival crevicular fluid: placebo-controlled randomized clinical trial.

To investigate the effect of photobiomodulation (PBM) and placebo on total amount of substance P in gingival crevicular fluid (GCF) pre- and postoperatively. Twenty-six patients having tooth with symptomatic apical periodontitis were enrolled in this study. GCF was collected preoperatively. The patients were assigned into two groups (n = 13), as follows: placebo and PBM. Sampling was repeated 7 days after root canal treatment. Two independent samples T test was used for analyzing of the differences between preoperative and postoperative substance P levels in GCF (p = .05). The Pearson correlation analysis was used for determination of correlation among substance P levels and other variables. For placebo group, there is no significant difference between preoperative and postoperative total amounts of substance P level (p = 0.553). For PBM group, postoperative total amount of substance P level was significantly higher than those of preoperative level (p = 0.005). Within the limitation of the present study, PBM has immunomodulation effect linked to the modulation of the total amount of substance P in the gingival crevicular fluid. Thai Clinical Trials Registry: TCTR20161228002.

Effect of photon-initiated photoacoustic streaming, passive ultrasonic, and sonic irrigation techniques on dentinal tubule penetration of irrigation solution: a confocal microscopic study.

OBJECTIVES: The aim of this in vitro study was to evaluate the efficacy of different irrigation techniques including laser-activated irrigation using an erbium:yttrium-aluminum-garnet (Er:YAG) laser with a novel tip design (photon-induced photoacoustic streaming (PIPS)), Er:YAG laser with Preciso tip, sonic activation, and passive ultrasonic activation on the final irrigation solution penetration into dentinal tubules by using a laser scanning confocal microscope. MATERIAL AND METHODS: In this study, 65 extracted single-rooted human mandibular premolars were instrumented up to size 40 and randomly divided into 5 groups (n = 13) based on the activation technique of the final irrigation solution as follows: conventional irrigation (control group), sonic activation, passive ultrasonic activation, Er:YAG-PIPS tip activation, and Er:YAG-Preciso tip activation. In each group, 5 mL of 5% NaOCl labeled with fluorescent dye was used during the activation as the final irrigation solution. Specimens were sectioned at 2.5 and 8 mm from the apex and then examined under a confocal microscope to calculate the dentinal tubule penetration area. Data were analyzed using two-way analysis of variance (ANOVA) and Tukey's post hoc tests (P = 0.05). RESULTS: Both Er:YAG laser (Preciso/PIPS) activations exhibited a significantly higher penetration area than the other groups (P < 0.05). Additionally, passive ultrasonic activation had significantly higher penetration than the sonic activation group and the control group. Statistically significant differences were also found between each root canal third (coronal > middle > apical) (P < 0.001). CONCLUSIONS: The results from the present study support the use of Er:YAG laser activation (Preciso/PIPS) to improve the effectiveness of the final irrigation procedure by increasing the irrigant penetration area into the dentinal tubules. CLINICAL RELEVANCE: The activation of the irrigant and the creation of the streaming with the Er:YAG laser have a positive effect on the irrigant penetration.

The effect of various occlusal reduction levels on postoperative pain in teeth with symptomatic apical periodontitis using computerized analysis: a prospective, randomized, double-blind study.

OBJECTIVE: The objective of this study was to evaluate the effect of various occlusal reduction levels on the postoperative pain in teeth diagnosed as symptomatic apical periodontitis by using a computerized analysis system. MATERIALS AND METHODS: Thirty-nine molar teeth with symptomatic apical periodontitis were included. After the root canal preparation and filling was performed, the subjects were divided into three groups according to the level of occlusal reduction determined by using T-Scan (T-Scan III for Windows, Tekscan Inc., South Boston, MA) as follows: (1) no reduction (control), (2) semi-reduction, and (3) full-reduction groups. Preoperative and postoperative pain levels using visual analogue scale, percussion pain, and analgesic intake were recorded for each subject. The data were evaluated statistically using two-way analysis of variance and Holm-Sidak post hoc tests at a 95 % confidence level (P = 0.05). RESULTS: There was no significant difference between the groups in terms of occlusal reduction (P > 0.005). CONCLUSION: Within the limitation of the present study, there were no significant differences among the no reduction, semi-reduction, and full-reduction groups at 1, 3, 5, and 7 days in terms of postoperative pain levels. CLINICAL RELEVANCE: Occlusal reduction, determined using a computerized analysis system, did not influence the postoperative pain in teeth diagnosed as symptomatic apical periodontitis.

The Effect of Diode Laser With Different Parameters on Root Fracture During Irrigation Procedure.

The aim of this study is to compare the effect of a single diode laser application and agitation of EDTA with diode laser with different parameters at different time intervals on root fracture. Ninety mandibular incisors were instrumented except the negative control group. The specimens were divided randomly into 10 groups according to final irrigation procedure: (G1) non-instrumented; (G2) distilled water; (G3) 15% EDTA; (G4) ultrasonically agitated EDTA; (G5) single 1.5W/100 Hz Diode laser; (G6) single 3W/100 Hz Diode laser; (G7) 1.5W/100 Hz Diode laser agitation of EDTA for 20 s; (G8) 1.5W/100 Hz Diode laser agitation of EDTA for 40 s; (G9) 3W/100 Hz Diode laser agitation of EDTA for 20 s; and (G10) 3W/100 Hz Diode laser agitation of EDTA for 40 s. The specimens were filled, mounted in acrylic resin, and compression strength test was performed on each specimen. Statistical analysis was carried out using one way ANOVA and Tukey's post hoc tests (P = 0.05). The statistical analysis revealed that there were statistically significant differences among the groups (P < 0.05). Laser-agitated irrigation with a 3W/100 Hz Diode laser for both 20 s and 40 s decreased the fracture resistance of teeth.

Dentinal tubule penetration of AH Plus, iRoot SP, MTA fillapex, and guttaflow bioseal root canal sealers after different final irrigation procedures: A confocal microscopic study.

BACKGROUND AND OBJECTIVE: Varied physical and chemical characteristic of root canal sealers and different irrigant agitation systems can influence the depth of penetration. The aim of this in vitro study was to use a laser scanning confocal microscope in order to assess the dentinal tubules penetration of various sealers after the application of different final irrigation techniques. STUDY DESIGN/MATERIALS AND METHODS: A total of 156 single-rooted extracted mandibular premolars were prepared up to size 40 and randomly distributed into four groups according to the sealer type (n = 39): AH Plus, iRoot SP, MTA Fillapex, and GF Bioseal. Each group was randomly subdivided into three groups according to the final irrigation protocol (n = 13): conventional needle irrigation (CI), photon-induced-photoacoustic streaming activation (PIPS), and passive ultrasonic irrigation (PUI). After the final irrigation procedures, the root canals were obturated with single gutta-percha and labeled sealer mixed with 0.1% fluorescent rhodamine B isothiocyanate. Specimens were sectioned at 2, 5, and 8 mm from the apex, and all the sections were examined under confocal microscope to calculate the dentinal tubule penetration area. Data were analyzed using three-way analysis of variance and Tukey's post hoc tests (P = 0.05). RESULTS: iRoot SP exhibited a significantly higher penetration area than the other groups (P < 0.001), although there were no statistically significant differences between AH Plus, MTA Fillapex, and GF Bioseal (P > 0.05). Er:YAG laser activation with PIPS and PUI had significantly higher penetration than CI (P < 0.001). Statistically significant differences were also determined at each root canal third (coronal > middle > apical; P < 0.001). CONCLUSIONS: The dentinal tubule penetration area was significantly affected by the selection of root canal sealer, final irrigation procedure, and root canal third. Use of iRoot with PIPS tip or PUI seems advantageous in dentinal tubule penetration.

Influence of ultrasonic and sonic activation of epoxy-amine resin-based sealer on penetration of sealer into lateral canals.

OBJECTIVES: The aim of this study was to evaluate the efficacy of sonic and ultrasonic activation of epoxy-amine resin-based root canal sealer (2Seal; VDW GmbH, München, Germany) on penetration of the sealer into lateral canals compared to non-activated filling. MATERIALS AND METHODS: Thirty-six single-rooted human anterior teeth were decoronated and prepared, using the ProTaper rotary system (Dentsply Maillefer, Ballaigues, Switzerland) to F4. After the completion of the clearing procedures, lateral canals were created at 2, 4, and 6 mm from the working length. The specimens were randomly divided into a control group (non-activated sealer application) and two experimental groups that received a sealer application with either sonic or ultrasonic activation. The root canals were filled using cold lateral compaction and images were obtained from each lateral canals at 40× magnification using a stereomicroscope. The sealer penetration was evaluated using a four-grade scoring system. The data were evaluated statistically using the Kruskal-Wallis and Mann-Whitney U tests with a 95 % confidence level (P = 0.05). RESULTS: The ultrasonic activation resulted in a better sealer penetration compared with the non-activated and sonically activated groups (P < 0.001). Sonic activation also resulted in better sealer penetration compared to the non-activated group (P < 0.001). CONCLUSIONS: The use of the ultrasonic activation of an epoxy-amine resin-based sealer promoted greater sealer penetration into the lateral canals. Sonic activation was not effective as ultrasonic activation, but was more effective than the non-activated group. CLINICAL RELEVANCE: The ultrasonic activation of an epoxy-amine resin-based sealer could be beneficial in filling procedures.

Effect of novel restorative materials and retention slots on fracture resistance of endodontically-treated teeth.

OBJECTIVES: The aim of this study was to evaluate the fracture resistance of endodontically-treated teeth restored with nano-hybrid composite resin, bulk-fill flowable and short fibre-reinforced-composite in the absence/presence of retention slots. MATERIALS AND METHODS: One hundred and ten extracted non-carious human mandibular molars received endodontic treatment followed by mesio-occlusodistal (MOD) cavities with 3 ± 0.2 mm thicknesses of buccal and lingual walls. Teeth were divided into two main groups according to the retention slot preparation. The dove-tail retention slots were prepared on the middle of opposite buccal and lingual walls to create mechanical interlocking. Each group was further divided into four sub-groups according to restorative material types: control (no restoration), nano-hybrid composite resin (Filtek™ Z550), bulk-fill flowable (Filtek™ Bulk Fill) and short fibre-reinforced-composite (everX Posterior™). Restored teeth were subjected to compressive load at a strain rate of 1 mm/min. The data were statistically analysed using two-way ANOVA and Tukey's test for multiple comparisons. RESULTS: The fracture resistance was significantly affected by the presence of the retentive slots and restorative material (p < 0.05). Restored teeth with retentive slots significantly increased the fracture resistance compared with restored teeth without retentive slots (p < 0.05). Short fibre-reinforced-composite with retentive slot cavities had significantly higher fracture resistance values compared with the other test groups (p < 0.05). CONCLUSIONS: The preparation of retention slots may increase the fracture resistance of endodontically-treated teeth, especially, when restored with short fibre-reinforced composite. The use of short fibre-reinforced composite with retentive slots could be an alternative technique to prevent cuspal fracture on endodontically-treated teeth with MOD cavity.

Effect of PIPS technique at different power settings on irrigating solution extrusion.

The aim of this study was to determine the effect of photon-induced photoacoustic streaming (PIPS) technique at different power settings on extrusion of irrigating solution. Root canal preparation was performed up to a #30 file on 64 extracted single-rooted mandibular premolar teeth, which were then divided into four groups. Each group was irrigated with one of the following irrigation methods: (a) irrigation with conventional irrigation open-ended needles, (b) continuous ultrasonic irrigation, (c) 0.3 W PIPS, or (d) 0.9 W PIPS. Apical extrusion of irrigating solution was evaluated using a modified model. The net weight of the extruded irrigating solution was measured for each group, and the resulting data were analysed statistically using Kruskal-Wallis at a 95 % confidence level (P < 0.05). Although the 0.9 W PIPS group resulted in the largest quantity of irrigation solution, the ultrasonic group was the smallest. However, the difference between these groups was not statistically significant at the 95 % level of confidence (P > 0.05). PIPS at both 0.3 W and 0.9 W resulted similar solution extrusion to the conventional irrigation or ultrasonic irrigation.

Effect of agitation of EDTA with 808-nm diode laser on dentin microhardness.

The aim of this study is to analyze the effect of agitation of ethylenediaminetetraacetic acid (EDTA) with diode laser at different agitation times on root dentin microhardness. Eighty-four specimens were divided randomly into seven groups, as follows: (1) distilled water, (2) 17% EDTA, (3) EDTA with 60 s ultrasonic agitation, (4) EDTA with 10 s laser agitation, (5) EDTA with 20 s laser agitation, (6) EDTA with 30 s laser agitation, and (7) EDTA with 40 s laser agitation. All of the specimens were irrigated with 5% NaOCl and distilled water except the distilled water group. Microhardness values were calculated before and after the procedures. Statistical analyses were performed using one-way ANOVA and Tukey post hoc tests. Statistically significant differences were determined between the distilled water and other groups. Also, statistically significant differences were observed between EDTA with 40 s laser agitation and EDTA, and EDTA with 10 and 20 s laser agitations. Ultrasonic agitation of EDTA affected microhardness of root dentin similar to EDTA (p > .05). All applications decreased the microhardness of root dentin when compared with distilled water. Agitation of EDTA with diode laser for 40 s caused more reduction in microhardness of root dentin when compared with EDTA.

Efficacy of different treatments of root canal walls on the pull-out bond strength of the fiber posts.

The aim of this study was to evaluate the efficacy of different irrigation protocols, including laser, on the retention of the fiber-reinforced composite posts to root canal dentinal walls using pull-out tests. Root canals of 60 single-rooted human teeth were filled and post spaces were prepared. Finally, specimens were divided randomly into five groups, each consisting of 12 specimens as follows: 5% NaOCl (control group), 17% EDTA, ultrasonic with 17% EDTA, single 1.5-W Er:YAG laser application, and the combined use of Er:YAG laser and 17% EDTA. After the root canal procedures, fiber posts were cemented to the root canal. Pull-out tests were performed using a universal testing machine at a crosshead speed of 2 mm/min. The data were analyzed using a one-way ANOVA and Bonferroni post hoc test (p = 0.05). Irradiation by the Er:YAG laser with/without EDTA positively affected the pull-out bond strength (p < 0.001). The pull-out strength was significantly higher in the ultrasonic group than that of the single irrigation with NaOCl or EDTA (p < 0.001). Er:YAG laser irradiation with/without EDTA enhanced the bond strength of fiber posts to root canal dentin walls. Additionally, ultrasonic-EDTA combination increased the bond strength.

The effect of photon-initiated photoacoustic streaming, ultrasonically and sonically irrigation techniques on the push-out bond strength of a resin sealer to the root dentin.

OBJECTIVES: The present study investigated the effects of various irrigation activation techniques, including laser-activated irrigation using a laser with a novel tip design (photon-induced photoacoustic streaming, PIPS) on the bond strength of an epoxy resin-based sealer to root dentin. MATERIALS AND METHODS: Seventy-two single-rooted human mandibular premolars were prepared using the rotary system to size 40 and randomly divided into four groups (n = 18) according to the final irrigation activation technique used as follows: conventional irrigation (CI), laser-activated irrigation with PIPS (LAI-PIPS), passive ultrasonic irrigation (PUI), and sonic irrigation (SI) with 5 mL of 17 % EDTA and 2.5 % NaOCl. The root canals were then obturated with gutta-percha and AH PlusJet sealer. A push-out test was used to measure the bond strength between the root canal dentin and the sealer. The data were analyzed using the two-way analysis of variance and least significant difference (LSD) post hoc tests (P = 0.05). RESULTS: The LAI-PIPS and PUI resulted in higher push-out values compared to CI and SI (P < 0.05). There were no statistically significant differences between CI and SI (P = 0.978) and between LAI-PIPS and PUI (P = 0.051). There was a statistically significant interaction between the final irrigant activation techniques used and root canal thirds (P < 0.05). A chi-square test revealed no significant differences in the failure mode within the groups (P > 0.05). CONCLUSIONS: The use of LAI-PIPS and PUI can provide higher bond strength of resin sealer to root dentin compared to CI and SI techniques. CLINICAL RELEVANCE: The activation of the irrigant and the creation of the streaming have a positive effect on the bond strength of the resin sealer to root dentin.

Bleaching effect of activation of hydrogen peroxide using photon-initiated photoacoustic streaming technique.

OBJECTIVES: This study aims to investigate the bleaching effectiveness of photon-initiated photoacoustic streaming (PIPS) using 35 % hydrogen peroxide on discolored teeth as compared with different devital bleaching techniques. MATERIALS AND METHODS: Fifty extracted human mandibular incisors were collected and artificially stained using sheep's blood. The teeth were then randomly divided into five groups according to the different bleaching procedures to be tested: walking bleach with sodium perborate and with 35 % hydrogen peroxide gel, both for 1 week; PIPS using 35 % hydrogen peroxide liquid for 30 min; and just 35 % hydrogen peroxide, as a liquid and as a gel (again, for 30 min). Spectrophotometric measurements were obtained on the buccal surfaces of the crowns, at the beginning, just after the bleaching procedures had been performed, and the following first, third, and seventh days. The ∆E values were calculated, and the data were analyzed with a two-way analysis of variance (P = 0.05). RESULTS: There were statistically significant differences between the PIPS technique using 35 % hydrogen peroxide liquid and the 35 % hydrogen peroxide liquid and gel without PIPS immediately after the procedures (P < 0.05). On Days 1, 3, and 7, the PIPS technique further bleached specimens more than all of the other techniques (P < 0.05). CONCLUSIONS: The PIPS technique using 35 % hydrogen peroxide was found to be more effective than all of the conventional techniques. CLINICAL RELEVANCE: Within limitations of this study, PIPS technique using hydrogen peroxide was superior to the conventional techniques. Further studies should be conducted to determine if the PIPS technique results in any complications, particularly cervical resorption.

Comparison of bleaching efficacy of two bleaching agents on teeth discoloured by different antibiotic combinations used in revascularization.

OBJECTIVES: To investigate the whitening effects of different bleaching agents on teeth discoloured by different antibiotic combinations of ciprofloxacin and metronidazole with minocycline, doxycycline, amoxicillin or cefaclor. MATERIALS AND METHODS: Forty extracted bovine incisors were collected and discoloured with triple antibiotic pastes (TAP) with minocycline, doxycycline, amoxicillin and cefaclor throughout 30 days. The specimens were then randomly divided into two subgroups and each group received different bleaching materials: 35% hydrogen peroxide and sodium perborate. Spectrophotometric measurements were obtained on the buccal surfaces of the crown, firstly in the beginning, then on the 4th, 8th and 12th days after the placement of the bleaching materials. The acceptability threshold was set to 3.5. The ∆E values were calculated and the data was analysed using the repeated measures analysis of variance (P = .05). RESULTS: All the test groups induced colour changes exceeding the acceptability threshold 30 days after the antibiotic pastes were placed. The 35% hydrogen peroxide was more effective than sodium perborate in the whitening of discoloured teeth by antibiotic pastes (P = .001). The whitening effect after the 8th and 12th days was significantly more than after 4 days of treatment (P <.001). The discolouration caused by the TAP with minocycline and cefaclor showed greater whitening compared to the TAP with doxycycline and amoxicillin groups (P <.05). CONCLUSIONS: The whitening treatment effect of 35% hydrogen peroxide on teeth discoloured by antibiotic pastes seems to have significantly outperformed the sodium perborate treatment. Both bleaching agents were allowed to bleach the teeth gradually each day and the effects on the 8th and 12th days were superior to the one on the 4th day. CLINICAL RELEVANCE: The use of 35% hydrogen peroxide could be advantageous to bleach the teeth discoloured with antibiotic pastes compared to sodium perborate.

Comparison of bond strength of self-etch adhesive to pulp chamber dentin after placement of calcium hydroxide and various antibiotic pastes.

OBJECTIVE: The aim of this study was to evaluate the effect of calcium hydroxide, double antibiotic paste (DAP) and triple antibiotic paste (TAP) with minocycline, cefaclor and amoxicillin on the micro tensile bond strength (µTBS) of self-etch adhesive to pulp chamber dentin. MATERIALS AND METHODS: Sixty mandibular first molars were cut horizontally and randomly divided into a control group and five experimental groups, which received an intra-canal dressing, as follows: calcium hydroxide, DAP, TAP with minocycline, TAP with cefaclor and TAP with amoxicillin. After storing the specimens for 4 weeks, the medicaments were removed by irrigation with 10 mL each of the following solution: 2.5% NaOCl, 17% EDTA and distilled water. A self-etch adhesive (Clearfil S3 Bond, Okayama, Japan) was applied and composite resin (Clearfil Majesty Posterior, Kuraray Medical Inc., Japan) was placed into the cavity. A µTBS test was performed on each specimen using a universal test machine. RESULTS: The DAP reduced the µTBS of self-etch adhesive compared to the control group, calcium hydroxide and TAP with minocycline and with cefaclor (p < 0.05). However, the other medicaments did not result in a decreased µTBS of self-etch adhesive to pulp chamber dentin as compared to the control group (p > 0.05). CONCLUSIONS: The use of DAP resulted in a reduced µTBS of self-etch adhesive to pulp chamber dentin.

Bond strength of self-adhesive resin cement to root dentin. Comparison of photon-initiated photoacoustic streaming technique with needle and ultrasonic irrigation.

OBJECTIVE: The aim of this study was to investigate the effects of photon-initiated photoacoustic streaming (PIPS) with various irrigating solutions on the bond strength of a self-adhesive resin cement to root dentin. MATERIALS AND METHODS: Seventy-two mandibular premolar roots were divided into six groups after post space preparation and treated with a needle irrigation with distilled water and NaOCl, ultrasonic irrigation with NaOCl, PIPS with NaOCl, PIPS with EDTA and PIPS with distilled water at 0.3 W, 15 Hz and 20 mJ per pulse for 60 s. Fiber posts were cemented with a newly marketed, self-adhesive resin cement. The data obtained from the push-out tests were analyzed using analysis of variance (ANOVA) and LSD post-hoc tests (p = 0.05). RESULTS: PIPS with distilled water resulted in higher push-out values than those of needle (with both distilled water and NaOCl) and ultrasonic irrigation (p < 0.05). CONCLUSIONS: The use of PIPS may provide higher bond strength of self-adhesive resin cement to root dentin than needle and ultrasonic irrigation techniques.

Effects of root canal preparation, various filling techniques and retreatment after filling on vertical root fracture and crack formation.

AIM: To investigate the incidence of cracks in root dentin after rotary instrumentation and filling with cold lateral condensation (CL), single-cone obturation (SC), and warm vertical compaction (WV) and retreatment of each filling system. METHODOLOGY: One-hundred sixty mandibular incisors were selected. Twenty teeth were left unprepared and served as a control, and the remaining 140 teeth were instrumented. Twenty teeth were assigned to an only prepared group. The remaining 120 teeth were assigned to three root canal filling groups and three retreatment groups (n = 20), as follows: CL, WV, SC, and retreatment of each filling system. All the roots were sectioned perpendicular to the long axis at 2, 4, 6, and 8 mm from the apex, and the sections were then observed under a stereomicroscope. The absence/presence of cracks and vertical root fractures were recorded, and the data were analyzed with a Pearson's chi-square test (P = 0.05). RESULTS: No complete vertical root fractures were observed in the unprepared and only prepared groups. However, vertical fractures were observed in the filling and retreatment groups. There were significantly more cracks in the retreatment after WV group than the other groups, with the exception of the retreatment after SC, WV, and CL resulted in significantly more cracks than the only prepared and SC. CONCLUSIONS: The filling techniques (except SC) caused more cracks than preparation only. The SC caused fewer cracks compared to the other filling techniques. The retreatment following the different filling techniques (except CL) caused more cracks than the original fillings.