Root canal volume change and transportation by Vortex Blue, ProTaper Next, and ProTaper Universal in curved root canals

OBJECTIVES: The aim of this study was to compare root canal volume change and canal transportation by Vortex Blue (VB; Dentsply Tulsa Dental Specialties), ProTaper Next (PTN; Dentsply Maillefer), and ProTaper Universal (PTU; Dentsply Maillefer) nickel-titanium rotary files in curved root canals. MATERIALS AND METHODS: Thirty canals with 20°–45° of curvature from extracted human molars were used. Root canal instrumentation was performed with VB, PTN, and PTU files up to #30.06, X3, and F3, respectively. Changes in root canal volume before and after the instrumentation, and the amount and direction of canal transportation at 1, 3, and 5 mm from the root apex were measured by using micro-computed tomography. Data of canal volume change were statistically analyzed using one-way analysis of variance and Tukey test, while data of amount and direction of transportation were analyzed using Kruskal-Wallis and Mann-Whitney U test. RESULTS: There were no significant differences among 3 groups in terms of canal volume change (p > 0.05). For the amount of transportation, PTN showed significantly less transportation than PTU at 3 mm level (p = 0.005). VB files showed no significant difference in canal transportation at all 3 levels with either PTN or PTU files. Also, VB files showed unique inward transportation tendency in the apical area. CONCLUSIONS: Other than PTN produced less amount of transportation than PTU at 3 mm level, all 3 file systems showed similar level of canal volume change and transportation, and VB file system could prepare the curved canals without significant shaping errors.

Corrigendum: Corrections to the funding. Quantification of the tug-back by measuring the pulling force and micro computed tomographic evaluation

Corrections to the funding. In this article, the year is missing from the funding information.

Quantification of the tug-back by measuring the pulling force and micro computed tomographic evaluation

OBJECTIVES: The aims of this study were to quantify tug-back by measuring the pulling force and investigate the correlation of clinical tug-back pulling force with in vitro gutta-percha (GP) cone adaptation score using micro-computed tomography (µCT). MATERIALS AND METHODS: Twenty-eight roots from human single-rooted teeth were divided into 2 groups. In the ProTaper Next (PTN) group, root canals were prepared with PTN, and in the ProFile (PF) group, root canals were prepared using PF (n = 14). The degree of tug-back was scored after selecting taper-matched GP cones. A novel method using a spring balance was designed to quantify the tug-back by measuring the pulling force. The correlation between tug-back scores, pulling force, and percentage of the gutta-percha occupied area (pGPOA) within apical 3 mm was investigated using µCT. The data were analyzed using Pearson's correlation analysis, one-way analysis of variance (ANOVA) and Tukey's test. RESULTS: Specimens with a strong tug-back had a mean pulling force of 1.24 N (range, 0.15–1.70 N). This study showed a positive correlation between tug-back score, pulling force, and pGPOA. However, there was no significant difference in these factors between the PTN and PF groups. Regardless of the groups, pGPOA and pulling force were significantly higher in the specimens with a higher tug-back score (p < 0.05). CONCLUSIONS: The degree of subjective tug-back was a definitive determinant for master cone adaptation in the root canal. The use of the tug-back scoring system and pulling force allows the interpretation of subjective tug-back in a more objective and quantitative manner.

Radiographic study of the distribution of maxillary intraosseous vascular canal in Koreans / 대한악안면성형재건외과학회지

BACKGROUND: This study aimed to investigate the distribution and prevalence of intraosseous loop (anastomosis between posterior superior alveolar artery and infraorbital artery) in Koreans detected on computed tomography (CT) images taken prior to sinus augmentation surgery. METHODS: From the 177 patients who underwent sinus augmentation with lateral approach at Ewha Womans University Department of Implant Dentistry, 284 CT scans were evaluated. The canal height (CH), ridge height (RH), and canal height from the sinus floor (CHS) were measured on para-axial views at the first premolar, first molar, and second molar. The horizontal positions of the bony canals in the lateral wall were also classified. One-way analysis of variance (ANOVA) and t test were used to estimate the statistical differences (p < 0.05). RESULTS: The intraosseous loops were detected in 92 CT scans (32 %). The mean vertical height of the bony canals from the alveolar crest (CH) was 23.45 +/- 2.81, 15.92 +/- 2.65, and 16.61 +/- 2.92 mm at the second premolar, first molar, and second molar, respectively. In the horizontal positions of the bony canals, intraosseous type was the most predominant. The canal heights more than 15 mm and less than 17 mm were most prevalent (33.7 %) and those under 13 mm were 12.0 %. CONCLUSIONS: The radiographic findings in this study could be used to decide the lateral osteotomy line avoiding potential vascular complication. However, only one third of the canals could be detected in CT scans; a precaution should be taken for the possibility of severe bleeding during lateral osteotomy.

Healing outcomes of root canal treatment for C-shaped mandibular second molars: a retrospective analysis

OBJECTIVES: This study aimed to evaluate the healing rate of non-surgical endodontic treatment between C-shaped and non-C-shaped mandibular second molars. MATERIALS AND METHODS: Clinical records and radiological images of patients who had undergone endodontic treatment on mandibular second molars between 2007 and 2014 were screened. The periapical index scoring system was applied to compare healing outcomes. Information about preoperative and postoperative factors as well as the demographic data of the patients was acquired and evaluated using chi-square and multinomial logistic regression tests. RESULTS: The total healing rate was 68.4%. Healing rates for the mandibular second molar were 70.9% in C-shaped canals (n = 79) and 66.6% in non-C-shaped ones (n = 117). The difference was not statistically significant. CONCLUSIONS: The presence of a C-shaped canal in the mandibular second molar did not have a significantly negative effect on healing after treatment. Instead, proper pulpal diagnosis and final restoration were indicated as having significantly greater influence on the healing outcomes of C-shaped and non-C-shaped canals, respectively.

Prevalence and features of distolingual roots in mandibular molars analyzed by cone-beam computed tomography

PURPOSE: This study evaluated the prevalence of distolingual roots in mandibular molars among Koreans, the root canal system associated with distolingual roots, and the concurrent appearance of a distolingual root in the mandibular first molar and a C-shaped canal in the mandibular second molar. MATERIALS AND METHODS: Cone-beam computed tomographic images of 264 patients were screened and examined. Axial sections of 1056 mandibular molars were evaluated to determine the number of roots. The interorifice distances from the distolingual canal to the distobuccal canal were also estimated. Using an image analysis program, the root canal curvature was calculated. Pearson's chi-square test, the paired t-test, one-way analysis of variance, and post-hoc analysis were performed. RESULTS: Distolingual roots were observed in 26.1% of the subjects. In cases where a distolingual root was observed in the mandibular molar, a significant difference was observed in the root canal curvature between the buccolingual and mesiodistal orientations. The maximum root canal curvature was most commonly observed in the mesiodistal orientation in the coronal portion, but in the apical portion, maximum root canal curvature was most often observed in the buccolingual orientation. CONCLUSION: The canal curvature of distolingual roots was found to be very complex, with a different direction in each portion. No correlation was found between the presence of a distolingual root in the mandibular first molar and the presence of a C-shaped canal in the mandibular second molar.

Cutting efficiency of apical preparation using ultrasonic tips with microprojections: confocal laser scanning microscopy study

OBJECTIVES: The purpose of this study was to compare the cutting efficiency of a newly developed microprojection tip and a diamond-coated tip under two different engine powers. MATERIALS AND METHODS: The apical 3-mm of each root was resected, and root-end preparation was performed with upward and downward pressure using one of the ultrasonic tips, KIS-1D (Obtura Spartan) or JT-5B (B&L Biotech Ltd.). The ultrasonic engine was set to power-1 or -4. Forty teeth were randomly divided into four groups: K1 (KIS-1D / Power-1), J1 (JT-5B / Power-1), K4 (KIS-1D / Power-4), and J4 (JT-5B / Power-4). The total time required for root-end preparation was recorded. All teeth were resected and the apical parts were evaluated for the number and length of cracks using a confocal scanning micrscope. The size of the root-end cavity and the width of the remaining dentin were recorded. The data were statistically analyzed using two-way analysis of variance and a Mann-Whitney test. RESULTS: There was no significant difference in the time required between the instrument groups, but the power-4 groups showed reduced preparation time for both instrument groups (p < 0.05). The K4 and J4 groups with a power-4 showed a significantly higher crack formation and a longer crack irrespective of the instruments. There was no significant difference in the remaining dentin thickness or any of the parameters after preparation. CONCLUSIONS: Ultrasonic tips with microprojections would be an option to substitute for the conventional ultrasonic tips with a diamond coating with the same clinical efficiency.

The Marginal Zone B Cells have an Increased Antibody Expression in Mice with Collagen-induced Arthritis / 대한류마티스학회지

OBJECTIVE: Mature B cells in the spleen of mouse can be divide into two main subsets: the follicular (FO) B cells and the marginal zone (MZ) B cells. In this study, we investigated which subtype of B cells is involved in the production of costimulatory molecules, cytokine and antibody during the induction of autoimmune arthritis. METHODS: The MZB and FOB cells isolated from DBA/1J induced- and collagen-induced arthritis (CIA) mice were stimulated with LPS or CpG. The costimulatory molecules were measured by flow cytometry (FACs). The cytokines were measured by ELISA. Production of antibodies by the MZB cells or FOB cells was measured by ELISA and the results were observed by confocal microscopy. RESULTS: The expression of co-stimulatory molecules was stronger in the MZB cells than that in the FOB cells. The production of cytokines (IL-10, IL-6) and antibodies was higher in the MZB cells. The IgG expression of the MZB cells, which is known to be associated with the acceleration of autoimmunity, was higher in the CIA mice than that in the DBA/1J mice. CONCLUSION: We observed that the MZB cells were increased in the CIA mice. The costimulatory molecules, cytokine and auto-antibodies were increased in the MZB cells compared to that of the FOB cells. Our results suggest that MZB cells mainly produce autoantibodies, and they play a key role in development of autoimmune arthritis.

The Effects of the Mixture of Fetal Bovine Serum and Poly-glycolic acid in Rabbit Calvarial Model

PURPOSE: This study was undertaken to investigate the osteogenic induction potential of PGA & FBS mixture on a calvarial defect in the rabbit. METHODS: Twenty New zealand white rabbit, weighing from 3.5-4kg were allocated into each of the three groups. Four 8mm sized bone defects were made on the parietal bone by drilling. In group I, the bony defects were implanted with 50 micrometer thickness film containing mixture of PGA and FBS. In group II, with PGA only film, & in group III, the bony defects were left with no implants. Results were evaluated by using morphologic change, radiographic study, biochemical study and histologic examination at 1 week (group I n=7, group II n=7, group III n=14), 2 weeks (group I n=6, group II n=6, group III n=12) and 3 weeks (group I n=7, group II n=7, group III n=14) following implantation. RESULTS: In the morphologic & radiographic study, the formation and corticalization of callus were observed earlier in group I than in groups II and III (p<0.05). In histological examination, group I showed more abundant and faster new bone formation than in group II and III. In biochemical analysis, group I displayed more activity than in group II and III. Group I also showed more abundant osteopontin, osteocalcin than groups II and III. CONCLUSION: In conclusion, the results demonstrate that the mixture of PGA and FBS has an effect on osteoblastic formation in the rabbit model. It is considered that further evaluation of long term results on resorption, immunologic tissue reaction and response of applied mixture in the human model will be needed.

The Effects of the Mixture of Fetal Bovine Serum and Poly-glycolic acid in Rabbit Calvarial Model

PURPOSE: This study was undertaken to investigate the osteogenic induction potential of PGA & FBS mixture on a calvarial defect in the rabbit. METHODS: Twenty New zealand white rabbit, weighing from 3.5-4kg were allocated into each of the three groups. Four 8mm sized bone defects were made on the parietal bone by drilling. In group I, the bony defects were implanted with 50 micrometer thickness film containing mixture of PGA and FBS. In group II, with PGA only film, & in group III, the bony defects were left with no implants. Results were evaluated by using morphologic change, radiographic study, biochemical study and histologic examination at 1 week (group I n=7, group II n=7, group III n=14), 2 weeks (group I n=6, group II n=6, group III n=12) and 3 weeks (group I n=7, group II n=7, group III n=14) following implantation. RESULTS: In the morphologic & radiographic study, the formation and corticalization of callus were observed earlier in group I than in groups II and III (p<0.05). In histological examination, group I showed more abundant and faster new bone formation than in group II and III. In biochemical analysis, group I displayed more activity than in group II and III. Group I also showed more abundant osteopontin, osteocalcin than groups II and III. CONCLUSION: In conclusion, the results demonstrate that the mixture of PGA and FBS has an effect on osteoblastic formation in the rabbit model. It is considered that further evaluation of long term results on resorption, immunologic tissue reaction and response of applied mixture in the human model will be needed.

The Growth of Human Osteoblasts in Culture Dishes Made with Poly-glycolic Acid Containing Fetal Bovine Serum

PURPOSE: An ideal bony construct can be divided into two broad categories: (1) the design and fabrication of biodegradable, biomimetic scaffolds that provide correct signals to induce osteogenesis: (2) the identification of an ideal source of osteoprogenitor cells to seed onto the scaffold. We selected poly-glycolic acid as a synthetic scaffold among various scaffolds because of these properties. Meanwhile, culture medium is supplemented with fetal bovine serum(FBS): such serum contains essential elements such as proteins, hormones, growth factors and trace minerals. The composition of FBS can be ideal for various cell growth in vitro. We supposed that we could enhance bone growth at a fractured site if FBS was mixed with synthetic scaffold-PGA. METHODS: We cultured human osteoblasts in five different prepared culture dishes made with FBS and PGA mixture. The mixtures contained different ratio of FBS, that is, 0, 1.5, 3, 7, and 10%. We cultured human osteoblasts for seven days and examined the growth and attachment of the cells at the 1st, 3rd, 5th, 7th days, respectively. RESULTS: In the mixture of 0% FBS and PGA, the growth of the cells lasted for one day. In 1.5 and 3% FBS and PGA, the growth of the cells was examined at the 3rd day, then minimally declined at the 5th and 7th days. In 7% FBS and PGA, the growth of the cells lasted for 5 days, then declined at the 7th day. In 10% FBS and PGA, the growth of the cells lasted for 5 days, then declined at the 7th day. Staining status of the osteoblasts with alkaline phosphatase showed pale pink color in 0% FBS and PGA groups, but bright pink color in 1.5, 3, 7, 10% FBS and PGA groups, especially in 3%, 7%. CONCLUSION: In consequence, the growth of human osteoblast was higher in the mixture of FBS and PGA groups than in pure PGA ones. It is assumed that the mixture of FBS and PGA affects the proliferation of human osteoblasts.

Injectable Cartilage Tissue Engineering Techniques Utilizing Fibrin Glue, Liquid Alginate and Pluronic F-127

Recently, a cartilage tissue utilizing the scaffold with liquid has been introduced for clinical application. In this study, three different bio-materials--fibrin glue, liquid alginate, and Pluronic F-112--were used to observe the feasibility of those liquid bio-materials in cartilage regeneration. The first stage of the experiment comprises gross observation of liquid bio-materials 24 hours after its injected into the subcutaneous pockets of New Zealand white rabbits. These bio-materials shows noticeable changes within the subcutaneous tissue of animal recipients. The second stage of the experiment is cartilage tissue engineering in athymic nude mouse utilizing these liquid bio- materials. Chondrocytes were harvested from the ear cartilage of rabbits. Tissue engineered constructs(TEC) were prepared by mixing the bio-materials and chondrocytes as 3 x 10(6) cells/ml. The TEC were injected into the dorsal subcutaneous tissue of rabbits as autologous grafts. The specimens were then harvested and analysed grossly and histologically at 4 weeks after injection. The sizes of the engineered cartilage tissue specimens varied according to the scaffold materials. The histologic evaluation was also performed after using the H/E stain and alcian blue stain. The specimen using fibrin glue showed homogeneous typical mature cartilage with lacunae surrounded by cartilage matrix. The specimen using liquid alginate showed homogeneous but relatively immature cartilage tissue formation throughout the specimen. The specimen using the Pluronic F-127 complex showed small areas of cartilage tissue islets which were less homogeneous in its distribution. In conclusion, it was possible to produce cartilage tissue by utilizing liquid scaffolds, such as fibrin glue, liquid alginate and Pluronic F-127. The cell-scaffold complex (TEC) could be successfully injected into subcutaneous tissue and changed into a semi-solid gel which ultimately produces a small amount of cartilage. This new concept of non-operative reconstruction method can be used for a variety of clinical purposes in the future.