Brasseler USA Research Articles

A Comparison of Coronal Tooth Discoloration Elicited by Various Endodontic Reparative Materials

IntroductionThe purpose of this study was to evaluate coronal tooth discoloration of ProRoot MTA (Dentsply Tulsa Dental, Johnson City, TN), white ProRoot MTA, EndoSequence Root Repair Material (Brasseler USA, Savannah, GA), MTA Angelus (Angelus Solucoes Odontologicas, Londrina, Brazil), and Biodentine (Septodont, Saint Maur des Fosses, France) when used in an ex vivo pulpotomy model. MethodsFreshly extracted mandibular third molars were collected and stored in 1% chloramine-T solution. Teeth were randomly assigned into 6 groups (n = 15) and stored individually in phosphate buffered saline at 37°C in 100% humidity. A standardized endodontic access was made in 5 groups. A 3-mm-thick increment of reparative material was placed on the pulpal floor, covered by glass ionomer, and the access opening restored with composite. Color (Commission Internationale de l'eclairage L*a*b*) was recorded with the Vita Easy Shade spectrophotometer (VITA Zahnfabrik, Bad Säckingen, Germany) on the midbuccal surface at baseline; after access preparation; after material placement; and then after 1, 7, 30, and 60 days. Changes in Commission Internationale de l'eclairage L*a*b* were measured for each experimental group and compared with ProRoot MTA (positive control) and no treatment (negative control) using the following equation: ΔE = ([Li − L0*]2 + [ai − a0*]2 + [bi − b0*]2)1/2. The mean results were analyzed within each group and between groups using the Friedman 2-way analysis post hoc test (P < .05). ResultsThere were no significant differences between white ProRoot MTA, MTA Angelus, and the positive control group. EndoSequence Root Repair Material and Biodentine produced significantly less discoloration than white ProRoot MTA, MTA Angelus, and ProRoot MTA. ConclusionsUnder the conditions of this study, EndoSequence and Biodentine had significantly less discoloration compared with white ProRoot MTA, MTA Angelus, and ProRoot MTA. The potential for discoloration may or may not correlate when materials are used clinically.

The Effects of Endosequence Root Repair Material on Differentiation of Dental Pulp Cells

IntroductionPulp capping techniques aim at preserving the vitality of pulp tissue, thus avoiding more invasive endodontic procedures. Endosequence Root Repair Material (ERRM; Brasseler USA, Savannah, GA) has been recently introduced as a potential pulp capping material. It is hypothesized that ERRM promotes the healing of dental tissue, thus maintaining the integrity and vitality of the pulp after pulp capping procedures. However, the exact mechanism by which ERRM affects the pulp after pulp capping procedures is still unknown. Therefore, the aim of this research was to delineate the effects of ERRM on the dental pulp and compare these effects to those of ProRoot MTA. MethodsThe effects of ERRM on dental pulp cells (DPCs) were compared with ProRoot mineral trioxide aggregate (MTA) (Tulsa Dental, Tulsa, OK). The effects of the 2 materials on the cells were analyzed using various assays such as flow cytometric analysis using FITC Annexin V and PI (BD Biosciences, Franklin Lakes, NJ), WST-1 proliferation assay (Millipore, Billerica, MA), vascular endothelial growth factor (VEGF) enzyme-linked immunosorbent assay, and an alkaline phosphatase (ALP) assay. Results were analyzed using analysis of variance with a post hoc Tukey test and the level of significance set at P ≤ .05. ResultsThe results showed that DPCs had similar percentages of viable cells when grown on either material. Furthermore, the proliferation rates, secretion of VEGF, and levels of ALP were similar for DPCs when cultured on either ERRM or ProRoot MTA. ConclusionsOverall, this study showed similar survival and proliferation of DPCs when in contact with ERRM or ProRoot MTA, which could make it a suitable alternative for pulp capping procedures.

Comparison of Accuracy of Calibration Ring Placement on 4 Different Endodontic Files

IntroductionThe purpose of the current study was to evaluate the accuracy and consistency of the placement of calibration rings on 4 file types: K3 (SybronEndo, Orange, CA), Vortex Blue (Tulsa Dentsply, Tulsa, OK), Kontrol Flex (Brasseler USA, Savannah, GA), and Lexicon (Tulsa Dentsply, Tulsa, OK). MethodsForty endodontic files, 10 of each type, were measured using a measuring microscope (Model W122; Gaertner Scientific Corp, Skokie, IL). Measurements were made from the file tip to the leading edge of 2 calibration rings and to the handle of each file. Each file measurement was performed 3 times by the same operator to ensure internal validity, and the 3 measurements were used to generate a mean for each file measurement. ResultsBased on a 1-factor analysis of variance and Tukey post hoc test (α = 0.05), K3 files displayed significantly greater accuracy and consistency in calibration ring and handle position. In contrast, Vortex Blue files were the least accurate, whereas both Kontrol Flex and Lexicon files were marked with similar precision. ConclusionsCalibration rings have been used by some operators to measure files during canal instrumentation. This study showed there was variation in placement of calibration rings and handles. Reliance on calibration rings and file handles as the sole means of measuring endodontic files may lead to inaccuracy in canal instrumentation.

Combined Antibacterial Effect of Sodium Hypochlorite and Root Canal Sealers against Enterococcus faecalis Biofilms in Dentin Canals

IntroductionThe present study aimed to evaluate the antibacterial effect of the combined use of sodium hypochlorite (NaOCl) and root canal sealers on Enterococcus faecalis biofilms using a dentin infection model. MethodsCells of E. faecalis were introduced into the dentinal tubules by centrifugation and incubated in brain-heart infusion for 3 weeks. The biofilms in dentin were first subjected to 5% NaOCl or sterile water for 10 minutes followed by an equal thickness of AH Plus (Dentsply International Inc, York, PA), Endosequence BC Sealer (Brasseler USA, Savannah, GA), or MTA Fillapex (Angelus Indústria de Produtos Odontológicos S/A, Londrina, Brazil) placed on the root canal wall of the dentin specimens for 7, 30, and 60 days. Gutta-percha and water were used in a similar manner as controls. The proportions of dead and live bacteria inside the dentinal tubules were assessed by confocal laser scanning microscopy and viability staining. ResultsThe combined use of NaOCl and sealers (30 and 60 days) killed significantly more bacteria than NaOCl or sealers alone (P < .05). NaOCl + MTA Fillapex was the most effective antibacterial combination by killing 83% bacteria in dentin tubules in 60 days. Thirty and 60 days of exposure to the sealers resulted in significantly more dead bacteria in dentin biofilms than 7-day exposures (P < .05). ConclusionsThe placement of root canal sealer after NaOCl treatment enhanced antibacterial effects against E. faecalis in the dentinal tubules. Little additional effect was obtained after 30 days of exposure to sealers.

The Effect of Obturation Technique on the Push-out Bond Strength of Calcium Silicate Sealers

IntroductionCalcium silicate–based sealers are known to have excellent sealing ability and bioactivities. They are typically recommended to be used in a single-cone (SC) technique. No studies have evaluated the effects of the thermoplastic obturation technique on the dentin interface of these sealers. The purpose of this study was to evaluate the push-out bond strengths of MTA Plus Sealer (Avalon Biomed Inc, Bradenton, FL) and EndoSequence BC Sealer (BC; Brasseler USA, Savannah, GA) when they were used in a thermoplastic technique. MethodsFifty single-rooted human extracted teeth were randomly divided into 5 groups (n = 10), instrumented, and obturated with the SC technique or continuous wave (CW) technique: group 1, BC-SC; group 2, BC-CW; group 3, MTA Plus–SC; group 4, MTA Plus–CW; and group 5, AH Plus (Dentsply DeTrey, Konstanz, Germany)–CW. The roots were sectioned into 1.0-mm-thick slices, and bond strengths were measured using a standardized push-out test. The mode of failure was determined by visual inspection under magnification. ResultsThe MTA Plus–CW had statistically significant lower bond strengths than all other groups. The BC-SC group had statistically higher bond strengths than the MTA Plus–SC and AH Plus–CW groups. No significant differences were seen among the other groups. Modes of failure were predominately cohesive or mixed except for group 4 (ie, MTA Plus–CW) in which nearly half the specimens had no visible sealer. ConclusionsBC and MTA Plus sealer showed favorable bond strengths when used in an SC technique. The CW obturation technique decreased the bond strengths of these sealers.

Antifungal Activity of Endosequence Root Repair Material and Mineral Trioxide Aggregate

IntroductionThe purpose of this study was to investigate the antifungal activity of Endosequence Root Repair Material (ERRM; Brasseler USA, Savannah, GA) as compared with mineral trioxide aggregate (MTA) using Candida albicans. MethodsAll materials were packed into sterilized intravenous tubing to obtain standardized samples and allowed to set for 3 or 24 hours and then exposed to a suspension of C. albicans for incubations of 24 or 48 hours. To analyze the mechanisms of the material's antifungal activity, additional samples of each test material were prepared in the same manner and allowed to set for 24 hours; these were then incubated in a culture medium for 24 hours. The pH of each conditioned media was measured before transferring to wells containing C. albicans. The development of biofilm was analyzed after 24 and 48 hours with 2,3-bis (2-methoxy-4-nitro-5-sulfophenyl)-5-([phenyl amino] carbonyl)-2H-tetrazolium hydroxide reduction assay. ResultsMaterials in both experimental groups significantly limited biofilm formation at each interval (ie, 24 and 48 hours). After incubating for a 24-hour period in the presence of C. albicans, ERRM in both experimental groups showed a reduction in biofilm formation that was statistically significant in comparison with MTA. However, when set for 24 hours and incubated for 48 hours, gray MTA and white MTA showed a more substantial reduction in biofilm formation than comparable samples of ERRM. Cultured media conditioned with test materials showed statistically significant antifungal biofilm activity after 48 hours. ConclusionsAll materials tested have comparable antifungal biofilm activity. It appeared that changing the environment, such as the pH, contributed to this activity.

Comparison of the Surface Hardness among 3 Materials Used in an Experimental Apexification Model under Moist and Dry Environments

IntroductionProcedures used in single-visit or multiple-visit approaches to apical barrier creation were used with an experimental apexification model to test the surface hardness of 3 materials. The purpose of this study was to examine the microhardness of the materials after setting in moist or dry conditions. MethodsA simulated open apex and periapical environment model was created using polyethylene tubes placed into a porous block filled with phosphate-buffered saline. White ProRoot Mineral Trioxide Aggregate (MTA; Dentsply Tulsa Dental, Tulsa, OK), EndoSequence Root Repair Material (ESRRM; Brasseler USA, Savannah, GA), and Biodentine (BD; Septodont, Louisville, CO) were mixed and placed into the apical 4 mm of the tubes (N = 15). The moist group had a damp cotton pellet above the test materials (mineral trioxide aggregate or ESSRM) with Fuji II LC (GC America, Alsip, IL) sealing the coronal segment. The dry group had gutta-percha placed directly against the test materials with amalgam sealing the coronal segment. After 10 days of storage in 100% humidity at 37°C, samples were sectioned, and microhardness was independently measured at 2 mm and 4 mm from the apical end. Differences were assessed using analysis of variance and a Tukey post hoc test (α = .05). ResultsAnalysis of variance analyses showed no significant effect of wet or dry conditions on resultant material hardness. A Tukey post hoc test showed that using ESRRM and BD would not result in a significant difference in hardness, but using MTA would result in statistically significant different hardness values when compared with ESRRM or BD. ConclusionsEither a moist or dry environment could allow hardening of materials; thus, both methods could be acceptable for clinical treatment procedures.

Evaluation of Compressive Strength of Hydraulic Silicate-based Root-end Filling Materials

IntroductionHydraulic silicate cements such as mineral trioxide aggregate (MTA) have many clinical advantages. Newer hydraulic silicate materials have been developed that improve on the limitations of mineral trioxide aggregate such as the long setting time and difficult handling characteristics. The purpose of this study was to examine the effect of saline and fetal bovine serum (FBS) on the setting and compressive strength of the following hydraulic silicate cements: ProRoot MTA (white WMTA; Dentsply International, Tulsa Dental Specialties, Johnson City, TN), EndoSequence Root Repair Material (Brasseler USA, Savannah, GA), MTA Plus (MTAP; Avalon Biomed Inc, Bradenton, FL), and QuickSet (QS; Avalon Biomed Inc, Bradenton, FL). MethodsSamples of root-end filling materials were compacted into polyethylene molds. Samples were exposed to FBS or saline for 7 days. A universal testing machine was used to determine the compressive strengths. ResultsQS had significantly lower compressive strength than all other materials (P < .001). White MTA and MTAP mixed with liquid had lower compressive strengths after exposure to FBS compared with saline (P = .003). ERRM, MTAP mixed with gel, and QS were not affected by the exposure to FBS. ConclusionsNew silicate-based root-end filling materials, other than QS, have compressive strength similar to MTA. Within the limits of this study, premixed materials and those mixed with antiwashout gel maintain their compressive strength when exposed to biological fluids.

An Evaluation of Setting Time of Mineral Trioxide Aggregate and EndoSequence Root Repair Material in the Presence of Human Blood and Minimal Essential Media

IntroductionThe purpose of this study was to compare the ability of MTA (Dentsply Maillefer, Tulsa, OK) and EndoSequence Root Repair Material (ESRRM; Brasseler USA, Savannah, GA) to set in the presence of human blood and minimal essential media. MethodsA model was created using polymethyl methacrylate blocks each prepared with 10 standardized wells (2-mm diameter × 3-mm depth). Prepared ProRoot MTA (Dentsply Maillefer) and ESRRM were each placed in 6 separate blocks. The samples were distributed among the 4 different media (ie, blood, minimal essential media, blood and minimal essential media, and sterile saline as the control). Each block was submerged for 4, 5, 6, 8, 24, 36, and 48 hours in an incubator at 37°C with 100% humidity. ResultsThe results revealed that regardless of the type of media exposure, neither of the materials set at 4 or 6 hours. ESRRM was not set at 48 hours, whereas all of the MTA samples were set at 36 hours. ConclusionsThis outcome draws into question the proposed setting time given by each respective manufacturer. Furthermore, despite ESRRM being marketed as a direct competitor to MTA with superior handling properties, MTA consistently set at a faster rate under the conditions of this study.

Cytotoxicity and Alkaline Phosphatase Activity Evaluation of EndoSequence Root Repair Material

IntroductionThe purpose of this in vitro study was to evaluate the cytotoxicity and alkaline phosphatase (ALP) activity of a new bioceramic root repair material, EndoSequence Root Repair Material (ESRRM; Brasseler USA, Savannah, GA), and to compare these characteristics with those of ProRoot MTA (Dentsply Tulsa Dental, Tulsa, OK) and Geristore (GR; Den-Mat LLC, Santa Maria, CA). MethodsHuman Saos-2 osteoblast-like cells were exposed to 1-, 3-, and 7-day elutes of the materials (100% and 50% strength) for 24 hours after which the bioactivity and ALP activity of the cells were evaluated using a methylthiazol sulfophenyl (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) assay and para-Nitrophenylphosphate colorimetric assay, respectively. In the positive control group, Triton X-100 (Boehringer Mannheim Corp, Indianapolis, IN) was used to lyse the cells, representing 100% cytotoxicity, and in the negative control group cells received fresh culture medium only. Data were statistically analyzed using the unpaired t test and 1-way analysis of variance. ResultsThe results revealed that the bioactivity of the cells as well as ALP activity were significantly decreased after exposure to ESRRM elutes in almost all time periods, both in 100% and 50% concentrations, with the exception of ALP activity of day 1 elutes of ESRRM at 50% concentration. MTA did not change the bioactivity or ALP activity of the cells. GR elutes of 100% concentration reduced the bioactivity on days 1 and 3, whereas GR elutes of 50% concentration affected the cells only on day 1. None of the GR elutes had any effect on ALP activity of the cells. ConclusionsIt was concluded that ESRRM elutes of all time periods in general reduced the bioactivity and ALP activity of osteoblast-like cells. GR reduced bioactivity only, whereas MTA had no effect on the cells.

An In Vitro Comparison of Torsional Stress Properties of Three Different Rotary Nickel-Titanium Files with a Similar Cross-Sectional Design

IntroductionThe purpose of this study was to compare the in vitro torsional stress characteristics of Twisted Files (TFs; SybronEndo, Orange, CA) with 2 milled files of a similar cross-section: EndoSequence (Brasseler USA, Savannah, GA) and ProFile Vortex (DENTSPLY Tulsa Dental, Tulsa, OK). MethodsFile sizes of 25/.06 and 30/.06 from the 3 file types were compared (n = 20/group). Torsional stress resistance was evaluated by measuring the torque in grams per centimeters and the angle of rotation (°) required for instrument separation with the use of a torsiometer instrument. The fractured files were examined using a scanning electron microscope to look at deformation and fracture surface characteristics. The data were analyzed with analysis of variance to determine statistical differences. ResultsThe 3 file types showed a statistically significant difference in both the maximum torsional stress and the angle of rotation before failure. TFs displayed the least amount of torsional stress resistance and the highest angle of rotation. The 30/.06 size files of all 3 types withstood more torsional stress than the size 25/06 files of the same type. Within each file design, there was not a statistically significant difference in angular rotation between the 25/.06 and 30/.06 groups. The scanning electron microscopic analysis of all 3 file types revealed dimpling near the center of rotation on the fractured surface indicative of torsional stress. ConclusionsThe novel techniques used in manufacturing TFs do not make them more resistant to torsional stress as compared with milled nickel-titanium endodontic files of a similar cross-sectional design.

Effect of phosphate-buffered saline on push-out bond strength of a new bioceramic sealer to root canal dentin.

The aim of this study was to compare push-out bond strength of a new bioceramic endodontic sealer, EndoSequence BC sealer (Brasseler USA, Savannah, GA), used with gutta-percha in the presence or absence of phosphate-buffered saline solution (PBS) within the root canals. Forty single-rooted human teeth were prepared and randomly divided into four groups. Samples in groups 1 and 2 were dried, but those in groups 3 and 4 were moistened with PBS before obturation. All root canals were obturated with gutta-percha/EndoSequence BC sealer. The specimens were stored in PBS for 7 days in groups 1 and 3 and for 2 months in groups 2 and 4. Push-out bond strength values and failure modes were evaluated. The data on push-out bond strength were analyzed using two-way ANOVA. The mean value for the bond strength of the obturation material in moistened canals was significantly higher than that in dried ones at 1 week (P = 0.00). Contrarily, there was no significant difference between dried and moistened root canals at 2 months (P = 0.61). In dried canals, bond strength increased significantly with time but in moistened ones, the difference was not significant. Inspection of the specimens revealed the bond failure to be mainly cohesive for all groups. The presence of PBS within the root canals increased the bond strength of EndoSequence BC sealer/gutta-percha at 1 week. However, no difference was found between the bond strength of EndoSequence BC sealer/gutta-percha in the presence or absence of PBS in the root canals at 2 months.

Resistance to Fracture of Roots Obturated with Novel Canal-filling Systems

Introduction This study was conducted to evaluate and compare the fracture resistance of roots obturated with various contemporary canal-filling systems. Methods Fifty single-rooted extracted mandibular premolars were decoronated to obtain 13-mm root segments. Ten roots were left unprepared and unfilled (negative control). Forty canals were instrumented using 0.06 taper EndoSequence files (Brassler, Savannah, GA). Roots were divided according to the obturating system into 4 groups (n = 10): group 1: iRoot SP sealer (Innovative Bioceramix, Vancouver, Canada) + ActiV GP cone (Brasseler USA, Savanah, GA), group 2: iRoot SP sealer + gutta-percha (GP), group 3: ActiV GP sealer + ActiV GP cone, and group 4: ActiV GP sealer + GP. All groups were obturated using single-cone technique. The roots within each group were embedded in acrylic molds and subjected to the fracture resistance test in which a compressive loading (0.5 mm/min) was applied until fracture. Data were statistically analyzed (analysis of variance and Tukey post hoc test). Results The significantly highest fracture resistance was recorded for both the negative control group (381.4 ± 53.2 N) and group 1 (iRoot SP sealer/ActiV GP cone [372 ± 62.9 N]) with no significant difference between them, whereas the significantly lowest value was reported in group 4 (ActiV GP sealer/GP cone [288.3 ± 30.5 N]). Conclusion Bioceramic-based sealer (ie, iRoot SP) is a promising sealer in terms of increasing in vitro resistance to the fracture of endodontically treated roots particularly when accompanied with ActiV GP cones.

Retreatability of a Bioceramic Root Canal Sealing Material

Introduction The efficacy of retreatment techniques for BC Sealer (BCS) (Brasseler USA, Savannah, GA) removal has not yet been assessed. The purpose of this study was to evaluate the efficacy of solvent and rotary instrumentation in the removal of BCS when used in combination with gutta-percha (GP) as compared with AH Plus sealer (Dentsply, Tulsa, OK). Methods The mesiobuccal canals of 40 mandibular molars were instrumented and obturated with either GP/AH Plus with warm vertical compaction or GP/BCS using a single cone. The groups were subdivided into samples with the master GP cone placed to the working length (WL) or intentionally 2 mm short of the WL. Canals were then retreated using heat, chloroform, rotary instruments, and hand files. The ability to regain the WL and patency were evaluated as well as the time required to remove obturation material. Representative samples were also analyzed via scanning electron microscopy. Results The WL was not regained in 70% of samples with BCS/master cone short of the WL. Patency was not re-established in 20% of samples with BCS/master cone to the WL or in 70% of samples with BCS/master cone short of the WL. Conclusions Conventional retreatment techniques are not able to fully remove BCS.

Comparison of Intracanal EndoSequence Root Repair Material and ProRoot MTA to Induce pH Changes in Simulated Root Resorption Defects over 4 Weeks in Matched Pairs of Human Teeth

Introduction Intracanal mineral trioxide aggregate (MTA) may provide an alternative to calcium hydroxide in the treatment of external inflammatory root resorption. This in vitro study using human matched pairs of teeth compared white ProRoot MTA (WMTA; (Dentsply Tulsa Dental Specialties, Tulsa, OK) and an alternative material with purportedly improved handling properties, EndoSequence Root Repair Material (ES; Brasseler USA, Savannah, GA), by measuring pH in simulated root surface resorptive defects after intracanal placement. The null hypothesis tested was that there is no difference between WMTA and ES. Methods Bilaterally matched pairs ( n = 24) of extracted, human, single-rooted teeth were instrumented to apical size 50/.06, and root surface cavities were prepared at 5 mm and 2 mm from the apex. Root canals of experimental matched pairs ( n = 20) were filled with WMTA or ES; control pairs ( n = 4) were filled with calcium hydroxide (positive control [POS]) or saline (negative control [NEG]). Teeth were sealed coronally and apically and immersed in saline. The pH in root surface cavities was measured at 20 minutes, 3 hours, 24 hours, 1 week, 2 weeks, 3 weeks, and 4 weeks. Results The pH at 5 mm when compared with the 2-mm level was significantly higher for the WMTA, ES, and POS groups ( P < .05, paired t tests); therefore, each level was analyzed separately. At both the 2-mm and 5-mm levels, significant pH changes occurred over time in the WMTA, ES (both P < .0001, repeated-measures analysis of variance), and POS ( P < .0001, Friedman test) groups and not in the NEG group (mean pH = 7.32 ± 0.04, P > .05). There were no differences between WMTA and ES at 20 minutes and 3 hours at both levels or at 24 hours at 5mm. The pH of WMTA was higher than ES by 24 hours at the 2-mm level (8.79 vs 8.56, P < .05, paired t test) and after 1 week at the 5-mm level (8.91 vs 8.05, P < .0001) and was thereafter always significantly higher in WMTA compared with ES ( P < .0001). The null hypothesis was rejected. Conclusions In matched pairs of teeth, intracanal placement of WMTA compared with ES resulted in a higher pH in simulated root resorption defects that was time and root level dependent.

Setting Properties and Cytotoxicity Evaluation of a Premixed Bioceramic Root Canal Sealer

Introduction This study investigated the setting time and micohardness of a premixed calcium phosphate silicate–based sealer (EndoSequence BC Sealer; Brasseler USA, Savannah, GA) in the presence of different moisture contents (0–9 wt%). The moisture content that produced the most optimal setting properties was used to prepare set EndoSequence BC Sealer for cytotoxicity comparison with an epoxy resin–based sealer (AH Plus; Dentsply Caulk, Milford, DE). Methods Standardized disks were created with BC Sealer, AH Plus, Pulp Canal Sealer EWT (positive control) (SybronEndo, Orange CA), and Teflon (Small Parts Inc., Miami Lakes, FL; negative control). Disks were placed in Transwell Inserts, providing indirect contact with MC3T3-E1 cells. Succinate dehydrogenase activity of the cells was evaluated over a 6-week period using MTT ((3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Cytotoxicity profiles of BC Sealer and AH Plus were fitted with polynomial regression models. The time for 50% of the cells to survive ( T 0.5 ) was analyzed using the Wald statistic with a two-tailed significance level of 0.05. Results BC Sealer required at least 168 hours to reach the final setting using the Gilmore needle method, and its microhardeness significantly declined when water was included in the sealer ( P = .004). All set sealers exhibited severe cytotoxicity at 24 hours. The cytotoxicity of AH Plus gradually decreased and became noncytotoxic, whereas BC Sealer remained moderately cytotoxic over the 6-week period. A significant difference ( P < .001) was detected between T 0.5 of BC Sealer (5.10 weeks; 95% confidence interval [CI], 4.69–5.42, standard error [SE] = 0.09) and T 0.5 of AH Plus (0.86 weeks; 95% CI, 0.68–1.05; SE = 0.18). Conclusions Further studies are required to evaluate the correlation between the length of setting time of BC Sealer and its degree of cytotoxicity.

Cytotoxicity evaluation of endosequence root repair material

The purpose of this study was to evaluate the cytotoxicity of EndoSequence Root Repair Material (Brasseler USA, Savannah, GA) and compare it with gray and white MTA. Samples of 2 mg freshly mixed or set gray MTA (GMTA), white MTA (WMTA), EndoSequence Root Repair Material (ERRM), and AH26 were eluted with 300, 600, and 1,000 microL cell culture medium for 24 and 72 hours. L929 cells were seeded into 96-well plates at 3 x 10(4) cells/well and incubated with 100 microL elute from each elute group. Cells cultured only with culture medium served as negative control. AH26 was used as positive control. After 24 hours' incubation, cell cytotoxicity was evaluated by MTT assay. Cell viability was calculated as percentage of the control group. The results were analyzed with 1-way analysis of variance. For both set and fresh samples, there were no significant cell viability differences among GMTA, WMTA, and ERRM. Cell viability in the AH26 group was less than in all of the other 3 materials. This study suggests that ERRM may have cell viability similar to GMTA and WMTA in both set and fresh conditions.

Distortion and Breakage of Liberator, EndoSequence, and ProFile Systems in Severely Curved Roots of Molars

IntroductionThe aim of this study was to investigate the incidence of endodontic file distortion and breakage when the Liberator (Miltex Inc, York, PA), EndoSequence (Brasseler USA, Savannah, GA), and ProFile (Tulsa Dental Products, Tulsa, OK) systems were used to instrument severely curved root canals of extracted human molars. MethodsEighty-four roots of extracted human molars with curvatures measuring 40° to 80° were used. The roots were randomly assigned into four groups based on the rotary instrumentation system: group 1, ProFile (.04 taper); group 2, EndoSequence (.04 taper); group 3, Liberator (.04 taper); and group 4, Liberator (.02 taper). ResultsFile distortion was 19.4%, 10%, 44.4%, and 59.1% for the ProFile, EndoSequence, and Liberator .04 and Liberator .02 groups, respectively. There were statistically significant differences between the ProFile and Liberator .04 groups (p < 0.05), the ProFile and Liberator .02 groups (p < 0.01), the EndoSequence and Liberator .04 groups (p < 0.01), and the EndoSequence and Liberator .02 groups (p < 0.01). Broken files occurred in 2.8% of the ProFile group and 7.4% of the Liberator .04 group. There were no broken files in the EndoSequence or Liberator .02 groups. No statistically significant differences were found among the four groups (p = 0.28) with regard to file breakage. ConclusionIt can be concluded that more file distortions occurred in both Liberator groups than with either the ProFile or the EndoSequence groups to a statistically significant degree.

Conservative and Esthetic Cast Gold Fixed Partial Dentures—Inlay, Onlay, and Partial Veneer Retainers, Custom Composite Pontics, and Stress‐breakers: Part I: Fundamental Design Principles

Although in today's dental world implant restorations are considered the standard of care in the replacement of missing teeth, clinical contraindications and patient nonacceptance of implant placement can be encountered. Several scenarios are discussed here in which a single missing tooth can be restored with conservative fixed partial dentures (FPD) that employ cast gold retainers; each with a customized design in order to preserve tooth structure, maintain esthetics, and provide a long-term prognosis. The abutment teeth are prepared for conservative partial coverage restorations by using Brasseler burs (Brasseler USA, Savannah, GA, USA). Impressions are taken of the preparations, along with any retentive features, utilizing either the Vented Pin Channel technique or the Shooshan Plastic Pin technique. The latter technique utilizes Kodex twist drills and corresponding impression pins (Coltene Whaledent Inc., Mahwah, NJ, USA). The conservative FPD with non-rigid connectors is fabricated by using type III gold alloy. The pontic cage portion is chemically prepared utilizing the Panavia F2.0 cement kit (Kuraray America Inc., Houston, TX, USA) or other dual-polymerizing resin cement and restored with any type of direct composite resin material. A palette of opaquers and tints are used for chairside characterization of the esthetic pontic facing. The final polish of the pontic is completed by using FlexiDisc and FlexiBuff discs (Cosmedent Inc., Chicago, IL, USA). CLINICAL SIGNIFICANCE In cases where an implant restoration is contraindicated for replacement of a single tooth, a semi-precision FPD is a conservative, functional, and esthetic alternative.

Conservative and Esthetic Cast Gold Fixed Partial Dentures—Inlay, Onlay, and Partial Veneer Retainers, Custom Composite Pontics, and Stress Breakers: Part II: Utilization of Additional Retentive Features and Fabrication of Custom Pontic Facings

Although in today's dental world implant restorations are considered the standard of care in the replacement of missing teeth, clinical contraindications and patient nonacceptance of implant placement can be encountered. Several scenarios are discussed here in which a single missing tooth can be restored with conservative fixed partial dentures (FPD) that employ cast gold retainers; each with a customized design in order to preserve tooth structure, maintain esthetics, and provide a long-term prognosis. The abutment teeth are prepared for conservative partial coverage restorations by using Brasseler burs (Brasseler USA, Savannah, GA, USA). Impressions are taken of the preparations, along with any retentive features, utilizing either the Vented Pin Channel technique or the Shooshan Plastic Pin technique. The latter technique utilizes Kodex twist drills and corresponding impression pins (Coltene Whaledent Inc., Mahwah, NJ, USA). The conservative FPD with non-rigid connectors is fabricated by using type III gold alloy. The pontic cage portion is chemically prepared utilizing the Panavia F2.0 cement kit (Kuraray America Inc., Houston, TX, USA) or other dual-polymerizing resin cement and restored with any type of direct composite resin material. A palette of opaquers and tints are used for chairside characterization of the esthetic pontic facing. The final polish of the pontic is completed by using FlexiDisc and FlexiBuff discs (Cosmedent Inc., Chicago, IL, USA). CLINICAL SIGNIFICANCE In cases where an implant restoration is contraindicated for replacement of a single tooth, a semi-precision FPD is a conservative, functional, and esthetic alternative.