Comparison of antimicrobial efficacy of different disinfectants on the biofilm formation in dental unit water systems using dip slide and conventional methods: A pilot study.

OBJECTIVE: Biofilm formation in dental waterlines brings opportunistic infections, especially for immunosuppressive patients. This study aimed to determine biofilm-forming microorganisms by various methods and investigate disinfectants' effects on biofilm. MATERIALS & METHODS: In the study, samples were obtained from the waterlines of 10-15 aged six dental units, before (0 min.) and after chlorine dioxide (ClO2) and hypochlorous acid (HOCl) treatment (1, 5, 10, 20, and 30 min.), and total colony counts were performed using conventional surface smear method (SSM) and dip slide method (DSM). The Congo red agar and Christensen methods were used to examine the biofilm-forming properties of the isolates. Monitoring of biofilm presence was also visualized by SEM scanning. RESULTS: When DSM and SSM are compared in all units where ClO2 and HOCl are applied, DSM can detect bacterial growth even during periods of greater exposure to disinfectant application. Although DSM can achieve a value approaching 3% even at the 10th minute in units treated with HOCl; SSM does not show reproduction at the same disinfectant exposure and duration; It was observed that in the units where ClO2 was applied, the growth was no longer observed at the 10th minute with DSM, and SSM, 50% growth in the first minute of the units treated with ClO2 could not be detected in the 5th minute. CONCLUSIONS: It is concluded that it can be advisable to routinely disinfect the dental unit water systems with non-toxic doses of ClO2 application before patient treatments in clinics and also to perform contamination controls at regular intervals with DSM, which is a sensitive and very practical method. RESEARCH HIGHLIGHTS: It has been observed that the dip slide method can count bacteria more sensitively than conventional methods in dental water systems without the need for experienced personnel and equipment. The difference between biofilm formation in water systems before and after disinfectant exposure in SEM examinations is remarkable. The effects of ClO2 and HOCl on biofilm were investigated and bacterial growth was inhibited in dental units between 5 and 10 minutes with both disinfectants.

Cytotoxicity and genotoxicity of salicylate- and calcium silicate-based root canal sealers on primer human periodontal ligament fibroblasts.

The aim of this study was to evaluate the biocompatibility of epoxy-resin-based AHPlus, salicylate-based MTA-Fillapex and calcium silicate-based iRootSP root canal sealers. Cytotoxicity was assessed by XTT test. The extracts from sealers of different setting times were serially diluted. Cell viability was calculated as the percentage of the control group (100%). The optimal concentration of each sealer was used at genotoxicity test, and micronuclei formations were detected. Statistical analyses were done by using Kruskal-Wallis and Dunn post hoc test with Bonferroni correction. AHPlus and MTA-Fillapex showed the lowest percentage of cell viability at higher concentrations (1:1, 1:2, 1:4), especially at first 12 h. iRootSP showed higher viability at all concentrations and times than AHPlus and MTA-Fillapex. At genotoxicity assay, AHPlus increased the number of micronuclei. MTA-Fillapex slightly induced micronucleus formation (not significant) and iRootSP was not increased. In conclusion, calcium silicate-based iRootSP had lowest cytotoxic and genotoxic potential and can be considered as a highly biocompatible material.

Evaluation of the Antibacterial Effects of Single and Combined use of Different Irrigation Solutions Against Intracanal Enterococcus Faecalis.

OBJECTIVES: This study assessed the antibacterial activity of both separate and combined uses of 5.25% sodium hypochlorite (NaOCl), 2% chlorhexidine (CHX), 17% ethylenediaminetetraacetic acid (EDTA), 3% hydrogen peroxide (H2O2), MTAD, SmearClear (SC) and 13.8% chlorine dioxide (ClO2) irrigation solutions against Enterococcus faecalis. MATERIALS AND METHODS: Two hundred eighty single rooted human premolars were randomly grouped into 26 test and 2 control (negative and positive) groups and were incubated for 24 h with E. faecalis, except for the negative control group. The tested solutions were as follow: NaOCl; CHX; ClO2; MTAD; SC; EDTA; H2O2; NaOCl + CHX; NaOCl + MTAD; SC + NaOCl; EDTA + NaOCl; H2O2 + NaOCl; ClO2 + CHX; CHX + MTAD; SC + CHX; EDTA + CHX; CHX + H2O2; ClO2 + MTAD; SC + ClO2; EDTA + ClO2; ClO2 + H2O2; SC+MTAD; EDTA+MTAD; MTAD + H2O2; SC + H2O2; and EDTA + H2O2. Optic density values were recorded at 0, 6, 12, 18, 24, 30, 36, 42 and 48 h and bacterial growth curve created for each solution. RESULTS: The CHX, MTAD and ClO2 showed a high potential for the elimination of E. faecalis, both alone and in all combinations. The EDTA, H2O2, H2O2+ EDTA, H2O2 + NaOCl and SC + NaOCl groups showed less antibacterial activity than the other groups. The SC + CHX group showed the best antibacterial effect against E. faecalis. CONCLUSION: The SC + CHX combination can be recommended as the most effective irrigation regimen against E. faecalis in persistent endodontic infections.

Effects of chelating agents on the mineral content of root canal dentin.

OBJECTIVE: The objective of this in vitro study was to assess the effect of several chelating agents on the mineral content of root dentin. STUDY DESIGN: Extracted human mandibular incisor roots were prepared and divided into groups according to the following irrigation protocols: 1) 17% ethylenediaminetetraacetic acid (EDTA); 2) 10% citric acid solution; 3) 18% etidronate; 4) 2.25% peracetic acid; 5) and deionized water (control). Dentin chips were obtained (Gates-Glidden nos. 3, 4, and 5). The levels of different minerals were analyzed with the use of inductively coupled plasma-atomic emission spectrometry (ICP-AES). RESULTS: 1) Peracetic acid significantly decreased P, K, Mg, Na, and S levels compared with the other groups (P < .05). 2) S decreased by different levels in all of the chelating solutions (P < .05), and the greatest decrease was observed in peracetic acid. 3) Ca levels significantly decreased in peracetic acid, citric acid, and EDTA (P < .05). 4) Mn levels significantly decreased in the citric acid and peracetic acid groups (P < .05). 5) Na and Zn levels significantly decreased in the peracetic acid, citric acid, and etidronate groups (P < .05). CONCLUSIONS: The chelation agents can create different effects on mineral contents of root dentin, so it is important to know what effects each solution will have on root dentin before their clinical use. In addition, according to the results of this in vitro study, it might be recommended that peracetic acid, in particular, should be used with caution.

An alternative adhesive strategy to optimize bonding to root dentin.

INTRODUCTION: This study examined the hypothesis that the shear-bond strengths of AH Plus (AH) and Hybrid Root Seal (HRS) to root dentin might be optimized by using a powdered dentin-reinforced bonding procedure. METHODS: The surfaces of root halves obtained from extracted human premolars were ground (800-grit silicon carbide paper), treated (5.25% NaOCl 17% EDTA for 5 minutes followed by distilled water) and randomly allocated into two groups according to the sealer and then into three subgroups according to bonding procedure. Dentin particles with a maximum size of 25 µm were incorporated into the adhesive of Clearfil Liner Bond 2V, and groups were created as follows: no adhesive, adhesive alone, and with powdered dentin reinforced adhesive; 3 × 3 mm high buildups were created using sealer and allowed to set (37 °C, 100% humidity, 72 hours). Shear tests were performed (1 mm/min). Data were calculated as MPa and analyzed (two-way analysis of variance, Tukey test). RESULTS: A significant difference was found between the groups (P = .000). Adhesive or reinforced adhesive had a negative effect on the shear-bond strength of AH, but they significantly increased the shear-bond strength of HRS (P = .000). HRS showed a similar bond strength with either adhesive alone or adhesive reinforced with powdered dentin. AH group was characterized by mixed failure, whereas the predominant failure type of the HRS group was cohesive failure within the sealer. CONCLUSIONS: Reinforcing adhesive resin with powdered dentin may be considered an alternative for optimizing the bonding of methacrylate-based sealers to root dentin and might affect the shear bond strength.

Comparison of organic tissue dissolution capacities of sodium hypochlorite and chlorine dioxide.

The organic tissue dissolution properties of irrigating solutions are important for the success of endodontic treatment. Chlorine dioxide (ClO2) has been recently proposed as an irrigation solution in endodontics. The organic tissue dissolution property of sodium hypochlorite (NaOCl) is well-known and extensively investigated, but apparently no data have been published on tissue-dissolving properties of ClO2. The aim of this in vitro study was to compare organic tissue dissolution capacity of NaOCl and ClO2. In this study, 5.25% NaOCl, 13.8% ClO2, and, as a control, isotonic saline solutions (0.9% NaCl) were used. Thirty bovine pulp specimens were previously weighed and immersed for 20 minutes in each test solution (changing the solution every 2 minutes). The pulp specimens were then blotted dry and weighed again. The percentage of weight loss was calculated and statistically analyzed by using one-way analysis of variance and post hoc Tukey honestly significant difference tests. Saline solution did not dissolve the organic tissue. Both 5.25% NaOCl and 13.8% ClO2 dissolved the tissue pieces more effectively than saline control (P < .05). No statistically significant difference was found between the tissue-dissolving properties of 5.25% NaOCl and those of 13.8% ClO2 (P > .05). Within the limitations of this in vitro study, it was concluded that ClO2 and NaOCl are equally efficient for dissolving organic tissue.

Calcifications of the pulp chamber: prevalence and implicated factors.

The objectives of this study were to describe the prevalence of pulp chamber calcifications in a sample of Turkish dental patients and to report associations between presence of pulp chamber calcifications and dental status, gender, age, and cardiovascular diseases (CVDs). Data were collected through radiographic examination of periapical and bitewing radiographs of 15,326 teeth from 536 dental patients, comprising 270 male and 266 female patients aged between 13 and 65 years. Definite radiopaque focuses inside the radiolucent pulp chamber were defined as pulp chamber calcifications. When the pulp chamber was completely radiolucent, that tooth was scored as tooth without pulp chamber calcification. The dental status was scored as intact, carious, restored, or restored + carious. Pulp chamber calcifications were identified in 204 (38%) patients examined. Of the 15,326 teeth, 747 (4.8%) had pulp chamber calcifications. Gender and dental status were found to be correlated with the presence of pulp chamber calcifications. The high prevalence of pulp chamber calcifications in carious, restored, and restored + carious teeth support the view that the occurrence of pulp chamber calcifications can be a response to long-standing irritants. However, to report any associations between occurrence of pulp chamber calcifications and different dental or clinical status, further studies are still needed.

Effect of immediate and delayed post preparation on apical microleakage by using methacrylate-based EndoREZ sealer with or without accelerator.

The purpose of this study was to evaluate the effect of immediate and delayed post space preparation on the apical sealing ability of EndoREZ, a methacrylate-based dual-cured resin sealer, with or without accelerator. Fifty extracted human teeth were endodontically prepared and randomly divided into 6 groups. Teeth in experimental groups 1, 2, 3, and 4 (n = 10) were filled with resin-coated gutta-percha and either EndoREZ with accelerator (A+) or EndoREZ without accelerator (A-) by the lateral compaction technique. In group1 (A+) and group2 (A-), the post space was prepared immediately at the time of obturation. In groups 3 (A+) and 4 (A-), the post space was prepared after storage in 100% humidity at 37 degrees C for 1 week. Groups 5 and 6 (n = 5) represented positive and negative control groups, respectively. Leakage was determined by computerized fluid filtration device. Complete leakage was observed in group 5, and no leakage was evident in group 6 (P = 1.000). In experimental groups, mean apical microleakage values (microL/cmH(2)O/min(-1)) were as follows: group 1, 2.77 +/- 0.79(a); group 2, 2.88 +/- 1.38(a); group 3, 19.95 +/- 7.85(c); group 4, 6.20 +/- 2.09(b) (different letters indicate significantly different groups, P < .005). Immediate post space preparation achieved better sealing than delayed post preparation at the apical end, regardless of whether the EndoREZ accelerator was used. There was no significant difference between the (A+) and (A-) in immediate post space preparation. However, more leakage was found when using (A+) than (A-) in delayed post preparation. Under the conditions of this study, it was concluded that EndoREZ accelerator seems not to provide clinicians with any advantage for rapid transition from endodontic treatment to post-endodontic restorative procedures immediately after completion of root canal therapy.

Long-term evaluation of the influence of smear layer on the apical sealing ability of MTA.

The aim of this in vitro study was to investigate the effect of the smear layer on apical microleakage in teeth obturated with mineral trioxide aggregate (MTA). Fifty single-rooted central maxillary teeth were used in this study. All teeth were instrumented to size 60 by using the step-back technique. The selected teeth were randomly divided into 2 groups (n = 20). In the first group (smear [+]), the teeth were irrigated with only NaOCl (5.25%). In the second group (smear [-]), the teeth were irrigated with ethylenediaminetetraacetic acid (EDTA) (17%) and NaOCl (5.25%) to remove the smear layer. The teeth were then filled with MTA. The computerized fluid filtration method was used for evaluation of apical microleakage. The quantitative apical leakage of each tooth was measured after 2, 30, and 180 days. Statistical analysis was done with the Mann-Whitney U and Wilcoxon signed ranks tests. At the end of this study there was no difference in 2 days between the groups, but removal of the smear layer caused significantly more apical microleakage than when the smear layer was left intact for 30 and 180 days (P < .005). Within the constraints of this study it can be concluded that the apical microleakage of MTA is less when the smear layer is present than when it is absent.

The effect of different restoration techniques on the fracture resistance of endodontically-treated molars.

AIM: This study compared the fracture resistance of endodontically-treated mandibular molars with mesio-occluso-distal (MOD) cavities restored using different restoration techniques. METHODOLOGY: Sixty sound extracted mandibular molars were randomly assigned to six groups (n=10). Group 1 did not receive any preparation. The teeth in Groups 2-6 received root canal treatment and a MOD cavity preparation. The teeth in Group 2 were kept unrestored. Group 3 was restored conventionally with amalgam. Group 4 was restored with a dentin bonding system (DBS, Clearfil SE Bond) and resin composite (CR) (Clearfil Photoposterior). Group 5 was restored with indirect hybrid ceramic inlay material (Estenia). In Group 6, polyethylene ribbon fiber (Ribbond) was inserted into cavities in a buccal-to-lingual direction and the teeth were then restored with DBS and CR. After finishing and polishing, the specimens, except for Group 2, were loaded to failure by a chewing simulation device (60,000 cycles x 50 N load, 1.3 Hz frequency) in an artificial environment at 37 degrees C. Each tooth was subjected to compressive loading perpendicular to the occlusal surface at a crosshead speed of 1 mm/minute. The mean loads necessary to fracture were recorded in Newtons and the results were statistically analyzed. RESULTS: The mean fracture values were as follows: Group 1: 2485.3 +/- 193.98a, Group 2: 533.9 +/- 59.4a, Group 3: 1705.8 +/- 135.7a, Group 4: 2033.3 +/- 137.6cd, Group 5: 2121.3 +/- 156.5d, Group 6: 1908.9 +/- 132.2cd. There were statistically significant differences between the groups annotated with different letters. Thus, Group 1 (intact teeth) had the greatest fracture resistance and Group 2 (non-restored teeth) the poorest. No statistically significant differences were found between Groups 3 (amalgam), 4 (resin composite) and 6 (polyethylene ribbon fiber reinforced composite) (p > 0.05). Group 5 (indirect hybrid ceramic inlay) had greater fracture resistance than Group 3 (p < 0.05). CONCLUSIONS: Within the limitations of this study, although all of the restoration groups were stronger than the prepared-only group, none of the restoration techniques tested was able to completely restore the fracture resistance lost from MOD cavity preparation. However, use of indirect hybrid inlay restorations in these teeth may be recommended, because this restoration technique indicated more favorable fracture failure modes than other restoration techniques used in this study and particularly greater fracture strength than amalgam restorations. The promising result of indirect hybrid inlay restorations may need to be confirmed by long-term clinical studies.

Maxillary first molar with an unusual morphology: report of a rare case.

Variations in dental anatomy are found in all teeth. Knowledge of these variations, particularly concerning the location and treatment of all canals, is very important for the success of endodontic therapy, because the inability to find and properly treat the root canals may cause failures. Variations in canal morphology, such as extra canals, apical ramifications, apical deltas, or lateral canals, are commonly encountered, and their incidence and significance have been well documented. However, the clinician should also be aware of the possibility of the existence of fewer root and/or canal numbers. The goal of this clinical article is to describe root canal treatment in a maxillary first molar with the unusual morphology of a single root and a single canal.

Effect of unintentionally extruded calcium hydroxide paste including barium sulfate as a radiopaquing agent in treatment of teeth with periapical lesions: report of a case.

Calcium hydroxide [Ca(OH)2] has been widely used as short- or long-term intracanal antibacterial dressing material after endodontic treatment. In general when used in endodontics, Ca(OH)2 paste is composed of the powder, a vehicle, and a radiopacifier. To provide radiopacity, barium sulfate (BaSO4) powder is usually added to the paste. In this case report, BaSO4:Ca(OH)2 powders (ratio 1:8) and distilled water were mixed and applied as dressing material after root canals of mandibular left canine and premolar teeth with periapical lesions. However, the prepared paste was unintentionally extruded into the periapical lesion during application. The patient was seen 12 and 36 months later, at which point periapical healing was evaluated. At this time, it was observed that the periapical lesion had disappeared, but white radiopaque spots were seen at the place where calcium hydroxide remnants had originally been present. The presented case report reveals that when Ca(OH)2 paste that included BaSO4 was applied as an intracanal dressing and extruded through the periapical lesion associated with pulpless teeth, it had no detrimental effect. However, healing might take longer when Ca(OH)2 paste including BaSO4 is used, so deliberate overextension is not advocated.

Effect of a new restoration technique on fracture resistance of endodontically treated teeth.

The aim of the study was to investigate the effect of a new fiber-reinforced composite restoration technique on fracture resistance in endodontically treated premolars. Eighty sound extracted human mandibular premolars were assigned to four groups (n = 20). Group 1 did not receive any treatment. In groups 2, 3 and 4, the teeth received root canal treatment and a mesio-occluso-distal cavity preparation. Group 2 was kept unrestored. Group 3 was restored with a dentin bonding system and composite resin. In group 4, a piece of polyethylene ribbon fiber was inserted into the groove in a buccal to lingual direction during the restoration of teeth with dentin bonding system and composite resin. After finishing and polishing, the specimens were stored in 100% humidity at 37 degrees C for 24 h and placed at an angle of 45 degrees to the long axis of the tooth and subjected to compressive loading in a universal testing machine at a crosshead speed of 0.5 mm min(-1). The load necessary to fracture the samples was recorded in Newton (N) and submitted to Kruskal-Wallis anova and Mann-Whitney U-test. The fracture strength of the teeth reinforced with a combination of polyethylene fiber and composite resin were not significantly different than those that were restored with only composite resin (P > 0.05). However, most of the failure modes of the reinforced teeth were limited to the level of the enamel, while the other three groups showed fractures generally at the level of the dentin, cemento-enamel junction or more below (P < 0.05). Therefore, polyethylene ribbon fiber-reinforced composite resin restorations seemed a more reliable restorative technique than traditional composite restorations for extensive cavities.

Effect of elapsed time following bleaching on the shear bond strength of composite resin to enamel.

The purpose of this study was to investigate the effect of post-treatment time on the shear bond strength of composite resin to enamel after bleaching with 10% carbamide peroxide (CP) and 35% hydrogen peroxide (HP) bleaching systems. One hundred and thirty-five flattened labial enamel surfaces obtained from human mandibular incisors were divided into two bleaching groups of 10% CP (n = 60) and 35% HP (n = 60) and a control group (n = 15). Specimens in the control group (group 1) were not bleached. Each bleaching group was then divided into four subgroups (n = 15). For both CP and HP groups, group 2 consisted of specimens bonded immediately after bleaching. In groups 3, 4, and 5, specimens were immersed in artificial saliva for 24 h, 1 week, or 2 weeks after bleaching, respectively. After the specimens were bonded with Clearfil SE Bond and Clearfil ST, they were tested in shear until failure. For both CP and HP groups, shear bond strength of composite resin to enamel that was bonded immediately after bleaching was significantly lower than that of unbleached enamel (p < 0.05). However, in CP group restored after 24 h, the bond strength returned to values close to those of nonbleached enamel (p > 0.05). It took 1 week to return to conditions that lead to control bond values for HP bleaching applications (p > 0.05). The results of this study proved that immediate bonding of composite to enamel bleached with 10% CP and 35% HP gels result in a significant decrease in shear bond strength. It is advisable that composite resin application onto bleached enamel surfaces should be delayed at least 24 h for 10% CP and 1 week for 35% HP.

Replantation after extended dry storage of avulsed permanent incisors: report of a case.

A 15-year-old boy lost his maxillary right and left central incisor teeth in a bicycle accident. He was referred to our clinic 1 week after the injury. The crown-root integrities of both the teeth were not damaged. Although the teeth were stored under dry conditions for 1 week, reimplantation of the teeth was planned to retain the teeth in the mouth for as long a period as possible because of the patient's age. Following the debridement and sterilization of root surfaces in 2.5% NaOCl, root canals were prepared and filled with calcium hydroxide. Then, about 2 mm of the apexes were resected to ensure that the roots easily seated in the alveolar socket and the prepared cavities in root ends were obturated with the amalgam. The teeth were placed into their respective sockets and splinted temporarily. The root canal therapy was completed 5 weeks later. Ankylosis was observed radiographically after 10 months. The patient is now 23 years old and he is still able to use both the central incisors functionally. However, there is a pink appearance on the cervical buccal surface of left central incisor because of progressive replacement resorption. In this case, the new treatment plan is to perform a permanent restoration with dental implants following the extraction of both teeth. Even though the long-term prognosis is uncertain, this treatment technique has provided an advantage for the patient in his adolescent period by maintaining the height of alveolar bone and making the provision of an aesthetically acceptable permanent restoration at a later age possible.

Spontaneously healed horizontal root fracture in maxillary first premolar: report of a case.

Root fractures of the posterior teeth are rare and occur as a result of severe trauma. This study describes the horizontal root fracture of a maxillary first premolar. The fractured roots were discovered during a routine radiographic examination. The tooth was asymptomatic and responded positively to electric pulp testing. The patient reported accidental trauma, which occurred 14 years before. Our case is an example of spontaneously healed fractured roots. The interesting findings were that the healing was observed even in the presence of two roots, including preservation of the vitality of the pulp.

The effect of fiber insertion on fracture resistance of endodontically treated molars with MOD cavity and reattached fractured lingual cusps.

In this study, the effect of flowable composite reinforced with a leno wave ultra high modulus (LWUHM) polyethylene fiber (Ribbond) on fracture resistance of endodontically treated molars with MOD cavity and lingual cuspal fracture was evaluated. Sixty sound extracted human mandibular molars were randomly assigned to six groups (n = 10). Group 1 served as control. Teeth in groups 2-6 received root canal treatment and a MOD cavity preparation. Teeth in group 2 were kept unrestored. Lingual walls of specimens in groups 3-6 were fractured at the CEJ and reattached (C&B Super-Bond). Group 3 was kept unrestored, and group 4 was restored with a composite resin (CR) (AP-X). In group 5, a flowable resin (FR, Protect Liner F) and in group 6, a Ribbond in combination with FR were inserted inside the cavity before CR restoration. After finishing and polishing, the specimens were subjected to compressive loading perpendicular to the occlusal surface at a crosshead speed of 1 mm/min. The mean load necessary to fracture were recorded in Newton and the results were statistically analyzed. MOD cavity preparation reduced fracture resistance of endodontically treated teeth (p < 0.05). Fracture resistance of rebonded fractured specimens was found to be similar to that of the nonfractured samples (p > 0.05). Use of LWUHM polyethylene fiber Ribbond increased fracture strength of endodontically treated molar teeth with MOD cavity preparation and cuspal fracture (p < 0.05). As a result, it was concluded that the insertion of Ribbond inside the cavity has a positive effect on fracture strength of endodontically treated molar teeth with MOD cavity preparation and cuspal fracture.

The quantitative evaluation of apical sealing of four endodontic sealers.

The aim of this in vitro study was to evaluate the apical seal obtained with four root canal sealers: Rocanal 2, Sealapex, AH Plus, and RC Sealer. Forty root canals were prepared using the step-back technique. The specimens were divided into four groups of 10 samples and obturated by laterally condensed gutta-percha with one of the tested sealers. The computerized fluid filtration method was used for evaluation of apical sealing properties. The quantitative apical leakage of each specimen was measured after 7, 14, and 21 days. Statistical analysis indicated that the apical leakage of all sealers used in this study decreased gradually from 7 days to 21 days (p < 0.05). Sealapex showed better apical sealing than the other sealers at 7, 14, and 21 days (p < 0.05). RC Sealer, AH Plus, and Rocanal 2 showed similar apical leakage values at every period (p > 0.05).

Sealing properties of different resin-based root canal sealers.

In this study, a comparison of the sealing properties of three different resin-based sealers, AH26, Diaket, and EndoREZ with those of the root canal sealer zinc oxide-eugenol-based U/P Root Canal Sealer was performed. Eighty extracted single-rooted human mandibular first premolar teeth were used. The coronal part of each tooth was removed at the apical 17-mm of roots. The root canals were prepared to a size 7 with ProFile 0.06 taper Series 29 rotary instruments in a crown-down manner before lateral condensation of gutta-percha with the tested sealers (n = 20). A fluid filtration method was used for quantitative evaluation of apical leakage. Statistical analysis revealed that there were no significant differences between the resin-based sealers groups (AH26, Diaket, and EndoREZ) (p > 0.05). U/P Root Canal Sealer, zinc oxide-eugenol-based sealer, leaked significantly more than other tested groups (p < 0.05). Under the limitations of this study, resin-based root canal sealers were found more effective in sealing root canals than the zinc oxide-eugenol-based sealer.

Effect of home bleaching agents on the roughness and surface morphology of human enamel and dentine.

AIMS: Carbamide peroxide (CP) containing bleaching agents are now widely used in different concentrations. In this study, the effect of 10% and 15% CP containing home bleaching agents on the surface roughness and morphology of human enamel and dentine were evaluated in vitro. METHODS: 90 non-carious human mandibular incisors were divided randomly into two equal groups (enamel and dentine). The dentine group specimens were ground to expose dentine surfaces. The samples in both groups were then randomly divided into three main groups and then divided into three subgroups, according to bleaching application times (n=15). The samples in both enamel and dentine groups were treated with 10% CP at Group 1 and 4, 15% CP at Group 2 and 5 and distilled water at Group 3 and 6. The surface roughness of the samples was analysed before bleaching (1a, 2a, 3a for enamel, 4a, 5a, 6a for dentine), after 4hr (1b, 2b, 3b for enamel, 4b, 5b, 6b for dentine) and after 28hr of bleaching application (1c, 2c, 3c for enamel, 4c, 5c, 6c for dentine) using a computerised roughness tester. The surface morphologies of treated and control specimens were also examined by SEM. RESULTS: There were no statistically significant differences between the surface roughness of untreated control specimens and the specimens treated with the bleaching materials (10% and 15% CP) for both enamel and dentine at any given measurement time (p>0.05). CONCLUSION: Under the careful guidance of a dentist, home bleaching can be thought a reliable treatment for both stained enamel and dentine, regardless of whether 10% or 15% CP is used.