Su-Jung Shin

Tooth Discoloration of Immature Permanent Incisor Associated with Triple Antibiotic Therapy: A Case Report

INTRODUCTION A triple antibiotic mixture of ciprofloxacin, metronidazole, and minocycline was used as an intracanal medicament in an attempt to disinfect the root canal system for revascularization of a tooth with a necrotic pulp. However, discoloration developed after applying the triple antibiotic mixture. METHODS Six weeks after a triple antibiotic paste had been applied to the root canal of tooth #8 of a 7-year-old girl, the tooth showed a dark discoloration. An in vitro experiment with human extracted teeth was performed to determine which of the 3 antibiotics caused the tooth discoloration. Another experiment was then carried out to examine whether a currently used dentin bonding agent would prevent or reduce such discoloration. The degree of discoloration was assessed by using a colorimeter. RESULTS Among the components of the triple antibiotic paste, only minocycline caused the tooth discoloration. Moreover, the dentin bonding agent reduced the intensity of the discoloration but did not prevent it. CONCLUSIONS The possible esthetic problems with the tooth color should be considered when using minocycline as a canal medication.

Tissue Levels of Matrix Metalloproteinases in Pulps and Periapical Lesions

The purpose of this study was to evaluate the tissue levels of matrix metalloproteinase (MMP)-1, -2, -3 and their distributions in inflamed human dental pulps and periapical lesions. Samples were subjected to enzyme-linked immunosorbent assay and/or immunohistochemistry by using specific antibodies to MMP-1, -2, and -3. Results from enzyme-linked immunosorbent assay were analyzed by using the Mann-Whitney U test and presented as p values. The concentrations of MMP-1 in all experimental groups were significantly higher than in the control (p < 0.05). The acute pulpitis and control groups were significant different in terms of their MMP-2 levels (p < 0.05). The concentration of MMP-3 in acute pulpitis was significantly higher than the control and chronic pulpitis groups (p < 0.05). Immunohistochemically, MMP-1 and MMP-3 were localized in the infiltrating neutrophils, macrophages, and extracellular matrix of the acute pulpitis group. These results suggest that MMPs play an important role in the pulp tissue destruction of acute, inflamed pulp.

X-Ray diffraction analysis of White ProRoot MTA and Diadent BioAggregate

BioAggregate is a new product that was formulated for root-end filling, perforation repair, and pulp capping. This study examined the chemical differences between white mineral trioxide aggregate (MTA) and BioAggregate in both powder and set forms using X-ray diffraction. The results showed that white MTA and BioAggregate have a similar chemical composition with some differences: BioAggregate contains a significant amount of tantalum oxide instead of bismuth oxide. In both groups, similar peaks were observed in the set and powder form, but sharper and stronger peaks were observed in the powder samples.

Outcomes of Endodontic Micro-resurgery: A Prospective Clinical Study

INTRODUCTION This study examined the outcomes of endodontic resurgery by using current microsurgery techniques on failed teeth with previous endodontic surgery. Another goal was to determine any significant outcome predictors of endodontic surgery by determining the causes of failure in the first endodontic surgery. METHODS The data were collected from patients in the Department of Conservative Dentistry at the Dental College, Yonsei University in Seoul, Korea between March 2001 and May 2009. All 54 teeth that required surgical retreatment were included in this study. All surgical procedures were performed by using an operating microscope and biocompatible root-end filling materials such as mineral trioxide aggregate (MTA) or Super EBA. The patients were recalled every 6 months for 2 years and every year thereafter to assess the clinical and radiographic signs of healing. RESULTS The recall rate was 77.8% (42 of 54 patients). Of the 42 cases recalled, 39 cases were included in the success category, giving an overall success rate of 92.9%. The most common possible causes of failure were no root-end filling and incorrect root-end preparation. CONCLUSIONS The use of microsurgical techniques and biocompatible materials such as MTA and Super-EBA resulted in a high clinical success rate, even in endodontic resurgery.

Comparison of the cleaning efficacy of a new apical negative pressure irrigating system with conventional irrigation needles in the root canals

OBJECTIVES This study evaluated the efficacy of EndoVac system in comparison with that of a conventional needle irrigation method when the root canals were enlarged to various sizes. STUDY DESIGN Sixty-nine single-rooted teeth were divided into 3 groups according to the root canal irrigation system (24G and 30G needle and EndoVac). Each group was divided into 3 subgroups according to the MAF size (#25, #40, and #60). Four-micron-thick serial sections were prepared at 1.5 and 3.5 mm from the apical level and photographs were taken for the analysis. The influence of the irrigation system and apical size was evaluated using a 1-way ANOVA test and Tukeys test (P < .05). RESULTS At both levels, significant differences were detected between EndoVac system and conventional needle irrigation in removing debris (P < .05). The relationship between the MAF size and irrigation efficacy was found to have a positive relationship (P < .05). CONCLUSIONS EndoVac left significantly less debris behind than the conventional needle irrigation methods. Although all 3 irrigation methods resulted in clean root canals because the percentage occupied by remaining debris was very low in our specimens, larger apical instrumentation seemed to improve apical root canal debridement.

Effect of Proinflammatory Cytokines on the Expression and Regulation of Human Beta-Defensin 2 in Human Dental Pulp Cells

INTRODUCTION Although the expression of human beta-defensin-2 (hBD-2) in odontoblasts from human dental pulp (HDP) has been reported, the production of hBD-2 and its regulation remains poorly understood. The aim of this study was to investigate the effect of cytokines on the induction of hBD-2 and its signaling mechanisms in HDP cells. METHODS After stimulation with tumor necrosis factor alpha (TNF-alpha) and interleukin 1 alpha (IL-1 alpha), reverse-transcriptase polymerase chain reaction, Western blot, and enzyme-linked immunosorbent assay experiments were performed to evaluate the effects of these cytokines on the production of hBD-2. RESULTS TNF-alpha and IL-1 alpha synergistically increased hBD-2 messenger RNA levels, protein expression, and activity. The up-regulation of hBD-2 by cytokines was attenuated by pretreatment with inhibitors of PKC, JNK, p38, ERK MAPK, nuclear factor-kappaB, and adenosine monophosphate-activated protein kinase (AMPK). CONCLUSION These results suggest that TNF-alpha and IL-1 alpha up-regulate HBD-2 expression in HDP cells through the PKC, JNK MAPK, p38, ERK, NF-kappaB, and AMPK pathways. Thus, the induction of hBD-2 by proinflammatory cytokines might up-regulate the pulpal host immune defense system.

In vitro evaluation of bacterial leakage resistance of an ultrasonically placed mineral trioxide aggregate orthograde apical plug in teeth with wide open apexes: a preliminary study

OBJECTIVE The purpose of this study was to compare the sealing ability of an ultrasonically placed orthograde mineral trioxide aggregate (MTA) apical plug in open apices. STUDY DESIGN Thirty extracted human maxillary incisors were used. Experimental teeth were instrumented up to #100 file at the apex, and the 5 mm MTA apical barrier was placed with (group A; n = 11) or without (group B; n = 11) ultrasonic activation. Eight teeth served as control group. Bacterial leakage was assessed daily for 180 days using a double-chamber bacterial leakage model with Enterococcus faecalis. The results were analyzed with Fisher exact test. RESULTS After 60 days, the ratio of leaked samples showed significant difference between groups A (2 out of 10) and B (8 out of 11) (P < .05). The mean time elapsed before leakage showed significant difference between groups A (158 days) and B (23 days) (P < .05). CONCLUSIONS Ultrasonically placed orthograde MTA apical plugs were effective at delaying bacterial leakage.

Comparison of Clinical Outcomes of Endodontic Microsurgery: 1 Year versus Long-term Follow-up

INTRODUCTION The purpose of this study was to examine and compare the clinical outcome of endodontic microsurgery after 1 year of follow-up and over a period of 4 years. METHODS The database of the Department of Conservative Dentistry, Yonsei University, Seoul, South Korea, was searched for patients who had undergone endodontic microsurgery and had been evaluated 1 year after surgery and over a period of 4 years. Two examiners independently evaluated the postoperative radiographs taken 1 year after surgery and over a period of 4 years using Ruds criteria. To analyze and compare the success rate based on the observation period, the McNemar test was performed with a significance level of 0.05. RESULTS The study included 115 cases. Using Ruds criteria, the overall success rate of cases with 4 or more years of follow-up was 87.8% compared with 91.3% at 1 year of follow-up. There was no significant difference between the follow-up periods (P = .344). CONCLUSIONS There was no significant difference in the clinical outcome after endodontic microsurgery when comparing 1-year follow-up periods with longer follow-up periods.

The influence of bone tissue deficiency on the outcome of endodontic microsurgery: a prospective study.

INTRODUCTION This study assessed the influence of deficiencies of the periapical and marginal bone tissue on clinical outcomes after endodontic microsurgery. METHODS Data were collected from the Microscope Center of the Department of Conservative Dentistry at the Dental College of Yonsei University, Seoul, South Korea, between August 2004 and March 2011. In total, 199 teeth that required endodontic surgery were included in the study. During the surgical procedure, deficiencies of the periapical and marginal bone tissue were measured immediately before the flap was repositioned. The patients were recalled 6 months and 1 year after the surgical procedure to assess the clinical and radiographic signs of healing. The Students t test or the Mann-Whitney U test and logistic regression were performed to evaluate the parameters. Significant associations between the outcome and all the evaluation parameters were analyzed using the Pearson chi-square test or the Fishers exact test with a significance level of 0.05. RESULTS A recall rate of 67.8% (135/199 teeth) was obtained. The height of the buccal bone plate was the only significant predictor (P = .040) of the healing outcome, suggesting that teeth with a buccal bone plate >3 mm presented a higher success rate than teeth with a buccal bone plate that was ≤3 mm high (94.3% vs 68.8%, P < .001). CONCLUSIONS These data suggest that a favorable prognosis can be expected when teeth are covered with a buccal bone plate that is >3 mm in height regardless of the amount of marginal bone loss.

Comparison of Regrowth of Enterococcus faecalis in Dentinal Tubules after Sealing with Gutta-Percha or Resilon

The objective of this study was to compare the sealing ability of gutta-percha (GP) and Resilon on Enterococcus faecalis in the dentinal tubules. Bovine root dentin blocks were infected and filled with GP alone, GP with zinc oxide-eugenol sealer, GP with resin sealer, or Resilon with resin sealer. The blocks were incubated in Brain-Heart Infusion agar plates up to 4 weeks, after which dentin chips were collected from the canal walls. The optical density of the culture medium containing the dentin chips was measured and analyzed statistically. Our results indicated that none of the filling materials were able to prevent the regrowth of E. faecalis completely. Although we noted no significant differences in bacterial counts among those groups filled with sealers, different patterns of change in bacterial counts were noted regarding time points. Filling with Resilon and a resin-based sealer induced a significant reduction in the bacterial counts over time (P < .05).