Educational content of professional ethics in postgraduate dental education.

PURPOSE: Inclusion of proper educational content with respect to professional ethics in dental curricula is an important step to achieve objectives of ethics education especially in postgraduate programs when the time and opportunities for explicit instruction of ethics are limited. This study aimed to find and discuss the topics of ethics and professionalism for dental postgraduate programs. METHODS: A modified Delphi survey of experts' opinions with three rounds was conducted to establish a consensus on the need to teach professional ethics topics. The topics were identified through a literature review and according to the opinion of the experts. Items scored as highly important by over 80% of the participants in each round of the survey were considered educational needs. RESULTS: A total of 154 ethical issues were identified and classified into 29 topical categories to design the initial questionnaire. A consensus was developed on 24 ethics and professionalism topics for inclusion in the professional ethics curriculum for all dental postgraduate programs. CONCLUSIONS: Based on the results of this study, the same educational content in professional ethics is needed for all dental residency programs in all specialties. Most of the topics on which experts reached a consensus to be included in the ethics educational content were related to ethical and professional standards of conduct.

The Effect of Canal Dryness on Bond Strength of Bioceramic and Epoxy-resin Sealers after Irrigation with Sodium Hypochlorite or Chlorhexidine.

INTRODUCTION: The aim of this in vitro study was to evaluate the effect of canal dryness on the push-out bond strength of two resin sealers (AH-Plus and Adseal) and a bioceramic sealer (Endosequence BC sealer) after canal irrigation with sodium hypochlorite (NaOCl) and chlorhexidine (CHX). METHODS AND MATERIALS: A total of 18 extracted human premolars were used. Canals were prepared and were divided to two groups based on irrigation solution (either NaOCl or CHX). The samples were again divided based on pre-obturation canal condition (wet, half-wet and dry). The samples were sub-divided into 3 groups based on the sealer type; the teeth were obturated with gutta-percha and test sealers (Adseal, AH-Plus or BC sealer). A total number of 18 groups were available to be cut into dentine disks (12 disks in each group). The type of bond failure was also assessed in each group. Data were analyzed using the 3-way ANOVA, post hoc Tukey's tests, t-test and the Fisher's exact test. The level of significance was set at 0.05. RESULTS: The bond strength of Adseal was not affected by the canal condition or irrigation with either NaOCl or CHX. Although the bond strength of AH-Plus was not affected by the irrigant type, the highest bond strength was seen in dry canals. For Endosequence BC sealer, the canal conditions did not affect the bond strength; however, CHX reduced the bond strength. CONCLUSION: Bond strength of resin sealers was not affected by irrigation solution; however, canal moisture negatively affected the bond strength of AH-Plus. CHX reduced the bond strength of BC sealer.

Ex Vivo Comparison of Mtwo and RaCe Rotary File Systems in Root Canal Deviation: One File Only versus the Conventional Method.

OBJECTIVES: Cleaning and shaping of the root canal system is an important step in endodontic therapy. New instruments incorporate new preparation techniques that can improve the efficacy of cleaning and shaping. The aim of this study was to compare the efficacy of Mtwo and RaCe rotary file systems in straightening the canal curvature using only one file or the conventional method. MATERIALS AND METHODS: Sixty mesial roots of extracted human mandibular molars were prepared by RaCe and Mtwo nickel-titanium (NiTi) rotary files using the conventional and only one rotary file methods. The working length was 18 mm and the curvatures of the root canals were between 15-45°. By superimposing x-ray images before and after the instrumentation, deviation of the canals was assessed using Adobe Photoshop CS3 software. Preparation time was recorded. Data were analyzed using three-way ANOVA and Tukey's post hoc test. RESULTS: There were no significant differences between RaCe and Mtwo or between the two root canal preparation methods in root canal deviation in buccolingual and mesiodistal radiographs (P>0.05). Changes of root canal curvature in >35° subgroups were significantly more than in other subgroups with smaller canal curvatures. Preparation time was shorter in one file only technique. CONCLUSION: According to the results, the two rotary systems and the two root canal preparation methods had equal efficacy in straightening the canals; but the preparation time was shorter in one file only group.

Calcium Enriched Mixture and Mineral Trioxide Aggregate Activities against Enterococcus Faecalis in Presence of Dentin.

INTRODUCTION: The purpose of this in vitro study was to compare the antibacterial activity of Calcium Enriched Mixture (CEM) with ProRoot Mineral Trioxide Aggregate (MTA) against Enterococcus faecalis (E. faecalis) in the presence/absence of dentin powder. MATERIALS AND METHODS: Two series of freshly mixed (10, 50, and 100 mg), set crushed powder (10, 50, and 100 mg), and pieces of uncrushed set (50, 100 mg) of CEM and MTA were prepared (n = 32 groups). All samples were suspended in normal saline for direct exposure test against E. faecalis; in the second series, 50 mg of the dentin powder was also added to the solution. Dentin powder suspension and bacterial suspension served as negative and positive control groups, respectively (n = 2). The suspensions were incubated at room temperature for 1, 60, and 240 min; each group was tested five times and survival of the bacteria in test solutions was assessed by 10-fold serial dilutions and cultured on Brain Heart Infusion (BHI) plates. The plates were incubated at 37ºC. The mean values of log10 CFU were calculated and compared in all tested groups. The total number of tests added up to 510 times. RESULTS: In presence of dentin powder, freshly mixed powder from set materials, and pieces of uncrushed set materials of both tested cements killed > 95% of the bacterial cell in 1 min. Adding dentin powder caused an increase in antibacterial activity of freshly mixed powder from crushed set CEM and MTA but no acceleration in bacterial killing was observed, when dentin was mixed with set or uncrushed cements. Dentin powder alone reduced the number of viable bacteria in the 4-hour duration. There were no significant differences between different weights of freshly mixed, crushed set powder and uncrushed set of CEM cement and MTA at different times. CONCLUSION: Under the conditions of this in vitro study, CEM cement as well as MTA have antibacterial effects against E. faecalis. The addition of equal amounts of dentin powder to the suspension of CEM or MTA resulted in swifter elimination of bacteria.

Evaluation of the root and canal morphology of mandibular permanent anterior teeth in an Iranian population by cone-beam computed tomography.

OBJECTIVE: To evaluate differences in the root and canal configurations of mandibular permanent anterior incisors and canines in an Iranian population by means of Cone Beam CT (CBCT) images. MATERIALS AND METHODS: Four hundred CBCT images of mandibular permanent incisors and canines that met the inclusion criteria were evaluated. Vertucci's classification was used to evaluate the number of roots, number of root canals, root lengths, root curvatures and canal types. RESULTS: Totally 632 central incisors, 614 lateral incisors and 608 canines were evaluated. The average length of the mandibular central, lateral incisors and canines was 21.3±0.10, 21.9± 0.13 and 25.1± 0.11 mm, respectively. All of the mandibular central and lateral incisors had one root, but the incidence of single-rooted mandibular canines and two-rooted mandibular canines was 96.3% and 4.7%, respectively. The majority of mandibular central, lateral incisors and canines had one canal (72.7%, 70.6% and 71.8%, respectively). Five types of Vertucci canal configurations were seen in the evaluated teeth. Type 1 Vertucci configuration was the most prevalent configuration (72.3%, 70.6% and 71.8% for the central, lateral incisors and canines, respectively)), and type 5 Vertucci canal configuration was the least prevalent type seen (3.3%, 3.2% and 2.3% for the central, lateral incisors and canines, respectively). The most frequent root curvatures in these teeth were distally and buccally. No significant difference was seen between male and female patients regarding any of the parameters evaluated in this study (p>0.05). CONCLUSION: More attention should be given to the detection of additional canals and the recognition of canal curvature in Iranian patients.

Push-out bond strength of bioceramic materials in a synthetic tissue fluid.

OBJECTIVE: This study compared the push-out bond strength of EndoSequence Root Repair Material (ERRM) and Bioaggregate (BA), new bioceramic materials, to that of mineral trioxide aggregate (MTA) after incubation in phosphate-buffered saline (PBS), a synthetic tissue fluid, for either 1 week or 2 months. MATERIALS AND METHODS: One-hundred and twenty root sections were filled with ProRoot MTA, BA, or ERRM. Each tested material was then randomly divided into two subgroups (n = 20): root sections were immersed in PBS for 1 week or 2 months. The bond strengths were measured using a universal testing machine. After that, the failure modes were examined with stereomicroscopy and scanning electron microscopy (SEM). The push-out data and failure mode categories were analyzed by two-way ANOVA and chi-square tests, respectively. RESULTS: The bond strength of ERRM was significantly higher than that of BA and MTA at both incubation periods. No significant difference was found between the bond strength of MTA and BA at either 1 week or 2 months. Increasing the incubation time to 2 months resulted in a significant increase in bond strength of all the materials. The failure mode was mainly mixed for MTA and BA, but cohesive for ERRM at both incubation periods. CONCLUSION: ERRM had significantly higher bond strength to root canal walls compared to MTA and BA. Increasing the incubation time significantly improved the bond strength and bioactive reaction products of all materials.

Push-out bond strength of two root-end filling materials in root-end cavities prepared by Er,Cr:YSGG laser or ultrasonic technique.

This study compared the push-out bond strength of mineral trioxide aggregate (MTA) and a new endodontic cement (NEC) as root-end filling materials in root-end cavities prepared by ultrasonic technique (US) or Er,Cr:YSGG laser (L). Eighty single-rooted extracted human teeth were endodontically treated, apicectomised and randomly divided into four following groups (n = 20): US/MTA, US/NEC, L/MTA and L/NEC. In US/MTA and US/NEC groups, root-end cavities were prepared with ultrasonic retrotip and filled with MTA and NEC, respectively. In L/MTA and L/NEC groups, root-end cavities were prepared using Er,Cr:YSGG laser and filled with MTA and NEC, respectively. Each root was cut apically to create a 2 mm-thick root slice for measurement of bond strength using a universal testing machine. Then, all slices were examined to determine the mode of bond failure. Data were analysed using two-way anova. Root-end filling materials showed significantly higher bond strength in root-end cavities prepared using ultrasonic technique (US/MTA and US/NEC) (P < 0.001). The bond strengths of MTA and NEC did not differ significantly. The failure modes were mainly adhesive for MTA, but cohesive for NEC. In conclusion, bond strengths of MTA and NEC to root-end cavities were comparable and higher in ultrasonically prepared cavities.

Effect of ProRoot MTA, Portland cement, and amalgam on the expression of fibronectin, collagen I, and TGFß by human periodontal ligament fibroblasts in vitro.

CONTEXT: Today many materials have been introduced for root-end filling materials. One of them is mineral trioxide aggregate (MTA) that is mentioned as a gold standard. AIMS: The purpose of this in vitro study was to evaluate the reaction of human periodontal ligament fibroblasts to the root-end filling materials, such as ProRoot MTA, Portland cement, and amalgam. SETTINGS AND DESIGN: Eight impacted teeth were extracted in aseptic condition. The tissues around the roots were used to obtain fibroblast cells. After cell proliferation, they were cultured in the chamber slides and the extracts of the materials were added to the wells. MATERIALS AND METHODS: Immunocytochemical method for measuring the expression of Fibronectin, collagen I and transforming growth factor beta (TGF®) was performed by Olysia Bioreport Imaging Software. STATISTICAL ANALYSIS USED: The results were analyzed by SPSS 13.0 and Tukey post hoc test with P<0.05 as the limit of significance. RESULTS: Collagen expression in MTA specimens was higher than the other groups in 24 h significantly. After 48 h, the Portland cement group showed the most expression of collagen significantly and after 1 week, Portland cement and MTA groups had the most expression of collagen but there was no significant difference between these 2 groups. After 1 week, the Portland cement group demonstrated a higher amount of TGF® and fibronectin. CONCLUSIONS: The results suggest that Portland cement can be used as a less expensive root filling material with low toxicity. It has better effects than amalgam on the fibroblasts.

Comparison of AH26 Physicochemical Properties with Two AH26/Antibiotic Combinations.

INTRODUCTION: The purpose of this study was to compare the setting time and post-setting solubility, flow, film thickness and dimensional changes of AH26 root canal sealer with AH26-Antibiotic combination. MATERIALS AND METHODS: This study was performed according to British standard BS 6876 (2001) which tests the physicochemical properties of endodontic sealers. Three samples of each of tested materials including AH26 alone, AH26/amoxicillin and AH26/doxycycline were used to test each of the properties. They were prepared according to ISO protocols. RESULTS: The setting time of studied materials was 46 hours for AH26, 29 hours for AH26/amoxicillin, 49 hours for AH26/doxycycline. Flow test results were as follows, for AH 26, 15.6 mm; AH26/amoxicillin, 14.9 mm; AH26/doxycycline, 14.2 mm. Film thickness was 0.024 mm in AH26, 0.0283 mm in AH26/amoxicillin, 0.0276 mm AH26/doxycycline. The solubility of AH26 was 0.0076%, AH26/amoxicillin, 0.0113%, and for AH26/doxycycline, 0.013 %. Dimensional changes following setting was 0.07 mm, 2.6 mm, and 1.1 mm for AH 26, AH26/amoxicillin, and AH26/doxycycline, respectively. CONCLUSION: The physico-mechanical properties of AH26 antibiotic combinations were superior compared with AH26, with the exception of flow. Also, AH26/amoxicillin had a lower setting time than AH26. However, all values were within an acceptable range which conformed to ISO.

The effect of two post-space preparation techniques on the seal of resilon and gutta-percha obturation materials.

INTRODUCTION: The aim of this study was to compare the effect of post space preparation with Gates Glidden drills or hand files on the sealing ability of gutta-percha or Resilon obturation materials. MATERIALS AND METHODS: One-hundred and four single-rooted human teeth were instrumented and divided into four experimental groups (n=21 each) and two groups of positive and negative control (n=10). Forty-two roots of experimental groups were obturated with gutta-percha and Dorifill sealer; and 42 roots with Resilon/Epiphany self-etch using lateral compaction technique. Each gutta-percha or Resilon group was divided into two subgroups (n=21) and post-space prepared with either Gates Glidden drills or hand files and chloroform. After post space preparation, 5 mm of apical gutta-percha or Resilon was left intact. The whole system was sterilized with gamma-rays. Saliva leakage was tested using a split-chamber model. Specimens were monitored every 24 hours for 30 days. The data were analyzed using log-rank test and Cox regression analysis. RESULTS: There were no significant differences between the sealing ability of gutta-percha and Resilon. Furthermore, no significant difference was found between two different methods of post space preparation (P>0.05). CONCLUSION: Under the limitations of this ex vivo study, there were no significant differences between the sealing ability of Resilon and gutta-percha after post space preparation using Gates Glidden drills or hand files with the aid of chloroform.

Antimicrobial Effects of AH26 Sealer/Antibiotic Combinations Against Enterococcus Faecalis.

INTRODUCTION: The purpose of this in vitro study was to evaluate the antimicrobial effects of two antibiotics added to AH26 sealer against Enterococcus faecalis (EF). MATERIALS AND METHODS: The antimicrobial effects of two antibiotic (amoxicillin and doxycycline) that were added separately to AH26 sealer was evaluated by using the agar diffusion test and in vitro human root inoculation method. The freshly mixed sealers were placed in prepared wells inside agar plates inoculated with EF, and were incubated at 37(°)C. The zones of inhibition were measured at 24, 48, 72 hours and 7 days. Root specimens were prepared and obturated with lateral condensation technique. Samples were collected from infected root canals after 2 and 7 days of incubation and the number of colony-forming units (CFU) was determined. The data were analyzed using one-way and two-way ANOVA. RESULTS: The findings of this study revealed that sealer-antibiotic combination containing amoxicillin and doxycycline had a significant difference in the mean zones of inhibition when compared to AH26 sealer alone in all of the time periods (P<0.05). The minimum effective concentration against EF was one percent of sealer powder weight for both of amoxicillin and doxycyline. The mean log10 CFU in AH26-doxycyline combination group was significantly lower than other groups at 48 h incubation period (P<0.05). AH26-doxycycline combination group and AH26-Amoxicillin combination group killed bacteria (mean CFU=0) in the dentinal tubules at 7 days incubation period. CONCLUSION: In vitro root fillings carried out with gutta-percha and AH26-antibiotic combination were effective in killing EF in dentinal tubules.

An In Vitro Study of the Number of Distal Roots and Canals in mandibular First Molars in Iranian Population.

INTRODUCTION: The purpose of this study was to evaluate the number of distal roots and canals in mandibular first molars and their internal anatomy radiographically within Iranian population. MATERIALS AND METHODS: A total of 310 distal roots of mandibular first molars were incorporated in this study and evaluated in terms of number of roots and number and types of canals. Root canal systems were studied in vitro by means of radiography and based on Vertucci's classifications. RESULTS: It was shown that 4.5% of the teeth in this study had two distal roots, of which, 100% indicated type I for both distobuccal and distolingual roots. Among all the teeth, 43.2% had two canals, 24.2% two apical foramina, and 38.7% two orifices in their distal roots. According to Vertucci's classification 54.9% of the teeth were type I, 19% type II, 1.9% type III, 14.2% type IV, 4.2% type V, 1% type VI, 0.3% type VII and 0% type VIII. CONCLUSION: In as many as 43.2% of all teeth assessed in this study, bicanaled distal roots were observed, dentists are always recommended to search for the second canal in distal roots of mandibular first molars. In case the second canal in the distal root is missed, failure of endodontic treatment will be anticipated. A rectangular type access cavity design allows better visualization and negotiation of the probable second canals within the distal roots of mandibular first molars.