Long-term porosity and retreatability of oval-shaped canals obturated using two different methods with a novel tricalcium silicate sealer.

OBJECTIVE: To evaluate the percentage volume of voids and gaps in oval-shaped canals obturated using two different methods with a tricalcium silicate-based sealer after short- or long-term storage. The long-term effect of storage on the efficiency of removing filling material was also investigated. MATERIALS AND METHODS: Forty premolar teeth with oval-shaped canals were instrumented to Reciproc R25 and obturated using single cone obturation (SCO) or warm vertical compaction (WVC) techniques with gutta-percha and HiFlow sealer. The specimens were stored at 100% humidity and 37°C for 2 weeks or 6 months and scanned using micro-computed tomography. Initial retreatment was performed up to a Reciproc R40, and the operating time was recorded. The residual material in the canal received a supplementary procedure using XP-endo Finisher R (XPFR) files. After each retreatment procedure, the specimens were rescanned. RESULTS: The percentage volume of voids and gaps in the SCO group was higher than that of the WVC group at both 2 weeks and 6 months (P < 0.05). The percentage volume of the filling material removed after initial retreatment and XPFR cleaning was significantly higher in the 6-month group than in the 2-week groups (P < 0.05). The proportion of the residual material decreased significantly when XPFR files were used, compared to the initial retreatment group (P < 0.05) in both storage times. CONCLUSION: The efficiency of retreatment in the oval-shaped canal was closely related to the storage time rather than the filling technique using a tricalcium silicate sealer. The XPFR instrument proved effective in the removal of the remaining materials from the oval-shaped canal. CLINICAL RELEVANCE: Obturation of the oval-shaped canal with TSBS using the SCO technique in the coronal area needs to be optimized. The retreatment was less efficacious in freshly filled canals than aged filled canals.

Evaluation of Root Canal Dentin Erosion after Different Irrigation Methods Using Energy-dispersive X-ray Spectroscopy.

INTRODUCTION: The purpose of this study was to examine the level of erosion in root dentin caused by different irrigation methods and protocols. METHODS: Thirty-five extracted upper molar teeth were instrumented and divided into 7 groups to undergo treatment by different methods: negative control, GentleWave System (Sonendo Inc, Laguna Hills, CA), and syringe needle irrigation following different protocols. The teeth were instrumented to size #25/.08 or #30/.09 for needle irrigation groups and to ProTaper size S1 for the GentleWave group under 5% sodium hypochlorite (NaOCl). The needle irrigation groups were subjected to final rinses of 2 minutes of 3% NaOCl + 2 minutes of 8% EDTA (3% N2 + 8% E2), 2 minutes of 3% NaOCl + 2 minutes of 8% EDTA + 1 minute of 3% NaOCl (3% N2 + 8% E2 + 3% N1), 2 minutes of 5% NaOCl + 2 minutes of 17% EDTA (5% N2 + 17% E2), 2 minutes of 5% NaOCl + 2 minutes of 17% EDTA + 1 minute of 5% NaOCl (5% N2 + 17% E2 + 5% N1), and 5 minutes of 5% NaOCl + 5 minutes of 17% EDTA + 5 minutes of 5% NaOCl (5% N5 + 17% E5 + 5% N5), respectively. The root canal surface was observed by scanning electron microscopy, and the dentin composition was analyzed by continuous line scanning for 300 µm into dentin using energy-dispersive X-ray spectroscopy. RESULTS: A slight but statistically significant decrease of calcium and an increase of carbon was measured in the 5% N2 + 17% E2 group in comparison with the control; no significant difference was found among GentleWave, 3% N2 + 8% E2, and 5% N2 + 17% E2 (P > .05). A final 1-minute rinse with 3% or 5% NaOCl reduced calcium and phosphorus to a significantly lower level than in groups without a 1-minute final rinse (P < .05). Final irrigation with 5% NaOCl for 5 minutes removed almost all calcium and phosphorus. Scanning electron microscopy showed canal wall erosion when an additional final irrigation with NaOCl was done. CONCLUSIONS: NaOCl followed by final EDTA irrigation performed either by syringe needle or the GentleWave System caused minimal dentin erosion. Erosion was measured as increased loss of calcium and phosphorus in samples in which additional final irrigation was performed using NaOCl after EDTA.

Antibacterial activity of various root canal sealers and root-end filling materials in dentin blocks infected ex vivo with Enterococcus faecalis.

OBJECTIVE: The aim was to investigate the antibacterial activity of the root-end filling materials MTA and IRM, different endodontic sealers and calcium hydroxide [Ca(OH)2] in experimentally infected dentinal tubules. MATERIALS AND METHODS: Ninety-four human root segments were prepared and the root canals were enlarged to ISO size 90. After smear removal, the specimens were infected with Enterococcus faecalis for 3 weeks. The roots were divided into eight groups and filled either with MTA, IRM, Ca(OH)2, gutta-percha and EndoRez (ER)/GuttaFlow (GF)/AH Plus (AH+) or with Resilon and Epiphany (EpRe). One group of specimens was left unfilled for control. Half of the specimens were treated for 1 day and the other half for 7 days in humid conditions at 37°C. Dentin samples from each canal were collected by enlarging the canals to ISO size 150; thus a dentinal depth of 300 µm was sampled. The number of cultivable bacteria was determined for each specimen. Statistical significance was set to 5%. RESULTS: After 1-day or 7-days of treatment, compared to control, all materials (except ER and GF at day 7) significantly reduced the number of bacteria. At day 1 and day 7, no significant difference was found between ER and GF and between Ca(OH)2, AH+, EpRe, IRM and MTA. However, a significant difference was found between these two groups of materials (except between GF and EpRe at day 7). Significantly more bacteria were cultured in the ER, GF, EpRe and IRM groups at day 7 compared to day 1. CONCLUSIONS: All materials exerted varying degrees of antibacterial activity which generally tended to decrease with time. The most stable antibacterial effect throughout the 7-day period was for Ca(OH)2, AH+ and MTA.

High-purity hepatic lineage differentiated from dental pulp stem cells in serum-free medium.

INTRODUCTION: We have previously differentiated hepatocyte like cells from deciduous tooth pulp stem and extracted third molar pulp stem cells with a protocol that used fetal bovine serum, but it showed high contaminations of nondifferentiated cells. Both the lower purity of hepatically differentiated cells and usage of serum are obstacles for application of cell therapy or regenerative medicine. Objective of this study was to investigate the capacity for and purity of hepatocyte-like differentiation of CD117-positive dental pulp stem cells without serum. METHODS: Mesenchymal cells from human deciduous and extracted third molar pulp were isolated and expanded in vitro. We separated CD117-positive cells by using a magnetic-activated cell sorter. The cells were characterized immunofluorescently by using known stem cell markers. For hepatic differentiation, the media were supplemented with hepatic growth factor, insulin-transferrin-selenium-x, dexamethasone, and oncostatin M. Expression of hepatic markers alpha fetoprotein, albumin, hepatic nuclear factor-4 alpha, insulin-like growth factor-1, and carbamoyl phosphate synthetase was examined immunofluorescently after differentiation. The amount of differentiated cells was assessed by using flow cytometry. Glycogen storage and urea concentration in the medium were defined. RESULTS: Both cell cultures demonstrated a number of cells positive for all tested hepatic markers after differentiation, ie, albumin-positive cells were almost 90% of differentiated deciduous pulp cells. The concentration of urea in the media increased significantly after differentiation. Significant amount of cytoplasmic glycogen storage was found in the cells. CONCLUSIONS: Without serum both cell types differentiated into high-purity hepatocyte-like cells. These cells offer a source for hepatocyte lineage differentiation for transplantation in the future.

Technical aspects of endodontic treatment procedures among Lithuanian general dental practitioners.

OBJECTIVE: The purpose of this study was to gather information about the various aspects, technical and biological, of endodontic treatment as performed by Lithuanian general dental practitioners and to compare their choices with established endodontic treatment standards of undergraduate education. MATERIALS AND METHODS: Questionnaires were sent to all 2,850 Lithuanian dental practitioners. The structured questionnaire included inquiries about gender, duration of professional activity, working environment, details about instruments and materials. RESULTS: From total 1532 (53.8%) questionnaires were returned. Only responses from general dental practitioners (1431) were included. Of the respondents 66% never used a rubber dam. Most practitioners relied on conventional stainless steel instruments. The NiTi hand files were often and routinely used by 32.2% of the respondents. Sodium hypochlorite was the most popular choice as a root canal irrigant. Calcium hydroxide paste was used as an inter-appointment medicament. Cold-lateral condensation root filling method was used by 72.8% of the respondents while 15.6% used a paste for the root filling. CONCLUSIONS: The results of this study indicate that the recently graduated dental practitioners were following the recommended standard of endodontic treatment better than those with a longer time from the graduation. It is important to improve the quality of existing courses of continuous education in endodontology in order to ensure the necessary competency in clinical practice. The low use of a rubber dam and low adoption of new technologies in Lithuania is not acceptable and needs to be changed.

Expression of multiple stem cell markers in dental pulp cells cultured in serum-free media.

INTRODUCTION: Stem cell lines are usually grown in medium containing animal products. Fetal bovine serum (FBS) is an important additive for cell growth; however, the allergenic potential and the possibility of contamination when we use a medium containing serum would be a barrier to transplantation and consequently to the introduction of cell therapy methods into clinical applications. METHODS: Dental mesenchymal cells were isolated and expanded in vitro and maintained in 4 different serum-free media (SFMs): SFM#1 (ITS-X, embryotrophic factor [ETF]); SFM#2 (ITS-X); SFM#3 (ETF); and SFM#4 (ETF, sodium pyruvate, ascorbic acid, fibroblast growth factor [FGF-a], acidic). Viability, proliferative, and immunocytochemical tests for the cells were performed by using 4 stem cell markers (CD44H, CK19, nestin, and P63) for ectoderm, mesoderm, and endoderm. RESULTS: Viability tests showed a significant difference between the control and SFMs in both deciduous tooth pulp cells (DTPCs) and wisdom tooth pulp cells (WTPCs). However, all SFMs demonstrated 84%-90% viability, whereas the control showed 90%-93%. In both DTPCs and WTPCs, SFM#1 had the highest proliferation rate among the 4 SFMs. Immunocytochemistry stained positive stem cell markers most intensely in cells cultured with SFM#1. Furthermore, all stem cell markers for ectoderm, mesoderm, and endoderm were expressed in the cells cultured with SFM#1. CONCLUSIONS: SFM#1 showed an acceptable survival rate, the highest proliferation rate, and the strongest expression of all the stem cell markers. SFM#1 proved to be a suitable medium for the culture of human dental pulp stem cells and to preserve pluripotency in differentiation.

Deciduous and permanent dental pulp mesenchymal cells acquire hepatic morphologic and functional features in vitro.

INTRODUCTION: Mesenchymal stem cells display extensive proliferative capacity of multilineage differentiation. The stromal compartment of mesenchymal tissues is considered to harbor stem cells. We assessed the endodermal differentiation of mesenchymal cells from deciduous and wisdom tooth pulp. METHODS: Dental mesenchymal cells were isolated and expanded in vitro. After cell cultures had been established, cells were characterized using known stem cell markers. For hepatic differentiation the media was supplemented with hepatic growth factor, dexamethasone, Insulin-Transferrin-Selenium-X, and oncostatin. RESULTS: Both cultures showed a number of cells positive for specific hepatic markers including alpha-fetoprotein, albumin, and hepatic nuclear factor 4alpha after differentiation. Also, small clusters of cells positive for insulin-like growth factor 1 were found. The concentration of urea increased significantly in the media. Moreover, a significant amount of glycogen was found in the cells. CONCLUSION: Because the cells proved to produce specific hepatic proteins and to start functions specific for hepatocytes, such as storing glycogen and urea production, we may state that the mesenchymal cell cultures from wisdom and deciduous tooth pulp acquired morphologic and functional characteristics of hepatocytes.

In vitro antibacterial effect of calcium hydroxide combined with chlorhexidine or iodine potassium iodide on Enterococcus faecalis.

Several studies have shown a higher success rate of root canal therapy when the canal is free from bacteria at the time of obturation. Treatment strategies that are designed to eliminate this microflora should include agents that can effectively disinfect the root canal. Enterococcus faecalis is often associated with persistent endodontic infections. While in vivo studies have indicated calcium hydroxide to be the most effective all-purpose intracanal medicament, iodine potassium iodide (IKI) and chlorhexidine (CHX) may be able to kill calcium hydroxide-resistant bacteria. Supplementing the antibacterial activity of calcium hydroxide with IPI or CHX preparations was studied in bovine dentine blocks. While calcium hydroxide was unable to kill E. faecalis in the dentine, calcium hydroxide combined with IKI or CHX effectively disinfected the dentine. The addition of CHX or IKI did not affect the alkalinity of the calcium hydroxide suspensions. It may be assumed that combinations also have the potential to be used as long-term medication. Cytotoxicity tests using the neutral red method indicated that the combinations were no more toxic than their pure components.