Biomedical subjects

Syngcuk Kim

Publications and source records attributed to Syngcuk Kim.

12 recordsLinked to original sources

PubMed2005

An investigation of microleakage from root-end fillings in ultrasonic retrograde cavities with or without finishing: a quantitative analysis.

OBJECTIVE: The aim of this study was to make a quantitative assessment of the sealing ability of Super-EBA, IRM, and Pro Root MTA root-end fillings subjected to 3 different finishing techniques. STUDY DESIGN: Eighty-one ultrasonically prepared root-end cavities in human canines were separated randomly into 3 test groups of 27 roots each. The cavities were filled with Super-EBA, IRM, or Pro Root MTA and finished by ball burnishing. Sequentially, 18 roots from each group received a final smoothing with either a 30-fluted tungsten carbide finishing bur or a Zekrya carbide 28-mm bur. Samples were prepared and immersed in 2% methylene blue dye neutral solution for 12 hours. Roots were ground into a powder and prepared for analysis in an absorbency spectrophotometer. RESULTS: The results revealed that Pro Root MTA displayed significantly less mean dye microleakage ( P < .05) than Super-EBA and IRM root-end fillings. The Super-EBA root-end fillings, although presenting a greater mean dye microleakage, did not differ significantly from IRM ( P > .05). The finishing technique did not significantly ( P > .05) affect the incidence of microleakage among the materials tested. CONCLUSIONS: The favorable results obtained with MTA in leakage studies may be related to its good marginal adaptation. Spectrophotometric analysis may provide valuable information about the sealing capacity of root-end fillings. None of the procedures tested were able to avoid leakage, a finding that stresses the importance of the eradication of irritants within the root canal system.

Aluminum Compounds↗

PubMed2005

Periapical tissue responses and cementum regeneration with amalgam, SuperEBA, and MTA as root-end filling materials.

The purpose of this study was to compare the periapical tissue responses and cementum regeneration in response to three widely used root-end filling materials, amalgam, SuperEBA, and Mineral Trioxide Aggregate (MTA). These materials were placed using modern microsurgical techniques on endodontically treated dog premolars and molars. After 5 months, the cell and tissue reactions of surface-stained un-decalcified ground sections were evaluated by light microscopy and statistically analyzed. The major difference in the tissue responses to the three retrofilling materials were the degree of inflammation and types of inflammatory cells, number of fibrous capsule formations, cementum neoformation over these materials, osseous healing and resulting periodontal ligament thickness. MTA showed the most favorable periapical tissue response, with neoformation of cemental coverage over MTA. SuperEBA was superior to amalgam as a root-end filling material.

Aluminum Compounds↗

PubMed2005

The role of endothelial nitric oxide in the Substance P induced vasodilation in bovine dental pulp.

Vasodilation, an important response in neurogenic inflammation, involves release of Substance P (SP) from the sensory nerve endings. It is now well known that SP causes edema formation and vascular relaxation in nondental tissues, however, the SP vasodilatory mechanism in the dental pulp is not completely understood. Endothelium-dependent relaxation is mediated by nitric oxide (NO) release with consecutive intracellular cyclic-GMP elevation in many vascular preparations. Recently, it has been shown in different vascular systems that SP-induced vasodilation is mediated by cyclic-GMP production through different pathways involving endothelial NO or direct endothelial-independent pathways. In the present study, the role of endothelial NO in SP induced vasodilation in the dental pulp was investigated to better understand the inflammatory mechanisms. Freshly extracted bovine dental pulp was used to measure NO production. Sodium nitroprusside (SNP), L-NAME and SP were utilized to induce and to inhibit NO production in endothelial cells. Released NO byproducts were measured with chemiluminescence assay technique. The present data demonstrate that SP induces NO production by activating NOsynthase (NOS) in endothelial cells. The NOS inhibitor L-NAME blocks NO production completely. In conclusion, in the bovine dental pulp, SP-induced vascular relaxation can be mediated by inducing NOS, and subsequently NO production in endothelial cells.

Analysis of Variance↗

PubMed2004

The ProFile system.

The ProFile instruments were among the first nickel-titanium (NiTi) instruments to be marketed. This article describes the unique file design, clinical performance, safety concerns, and clinical applications of this system. Guidelines for NiTi rotary instrument usage need to be followed to minimize complications and maximize benefits.

Dental Alloys↗

PubMed2004

The microscope and endodontics.

The incorporation of the microscope in clinical endodontics has had profound effects on the way endodontics is done and has changed the field fundamentally. This article outlines the key prerequisites for the use of the microscope in nonsurgical endodontic procedures, discusses which procedures benefit from using the microscope, and addresses the issue of cost versus patient benefit.

Cost-Benefit Analysis↗

PubMed2004

Modern endodontic practice: instruments and techniques.

Like many other dental and medical specialties, endodontics has evolved and changed over the years. The changes that have occurred in the past 10 years, however, have been of great magnitude and profundity. The microscope, ultrasonic units with specially configured tips, superbly accurate microchip computerized apex locators, flexible nickel-titanium files in rotary engines, and greater emphasis on microscopic endodontic surgery have totally changed the way endodontics and endodontic surgery are practiced. Comparing these changes with formocreoszol medication, K-file and radiographic determination of working length are truly dramatic. These changes are bringing the specialty of endodontic practice into the twenty-first century with greater precision, fewer procedural errors, less discomfort to the patient, and faster case completions. Seven key advancements in endodontics were made in the last decade. This article discusses these advancements and their applicability to everyday practice.

Dental Pulp Cavity↗

PubMed2004

Histomorphometrical and clinical comparison of submerged and nonsubmerged implants subjected to experimental peri-implantitis in dogs.

OBJECTIVES: Soft and hard tissue healing around submerged and nonsubmerged versions of one dental implant design was evaluated in an experimental canine peri-implantitis model. MATERIAL AND METHODS: Forty-eight c.p. Ti-implants with integrated (one-piece=OPI) or screw-on (two-piece=TPI) abutments were inserted in edentulous mandibles of eight beagle dogs, one OPI and one TPI with connected abutments for nonsubmerged and one TPI without abutment (SMI) for submerged healing. After 3 months, all implants were functionally loaded, and at 4 months peri-implantitis was ligature-induced in one jaw side. Intravital polyfluorochrome labeling, monthly conventional radiography and gingival probing of all 48 implants were performed until sacrifice 8 months postimplantation. Undecalcified ground sections in the bucco-lingual and mesio-distal planes of four dogs (23 implants, one implant lost) were evaluated by light and fluorescence microscopy. The immunohistochemical and SEM-vascular corrosion cast results of the four other dogs (24 implants) will be reported elsewhere. Levels of alveolar bone-to-implant contact (ABICL), alveolar crest (ACL) and junctional epithelium-to-implant contact were determined by computer-assisted histometry. Peri-implant alveolar bone loss (=saucerization) was assessed on the radiographs and calculated as ACL minus ABICL from histometric data. RESULTS: Around SMIs and OPIs without ligature less plaque adhesion and lower gingival indices were found when compared to TPIs. Radiologically, all ligatured, but also some nonligatured implants showed alveolar bone loss. Histometry demonstrated reduced ABICL around all these implants. Saucerization was more pronounced on the lingual and mesio-distal sides. Particularly around TPIs, bone resorption was still active or bone formation was impaired on fluorochrome labeling. Only around SMIs and one OPI without ligature continuing alveolar bone formation reflected by gains in ABICL were found. CONCLUSION: The clinical and histometric results of this study demonstrate that healing of submerged SMIs was not impaired by the two-stage procedure, resulting in equally good healing as around nonsubmerged OPIs. However, peri-implantitis plaque-induced by ligature and/or dilated abutment connection microgaps in TPIs affected alveolar bone-to-implant contacts more than transmucosal or submerged healing mechanisms.

Alveolar Bone Loss↗

PubMed2003

Analysis of continuous-wave obturation using a single-cone and hybrid technique.

This study analyzed the adaptation of gutta-percha to prepared root canal walls using two obturation techniques and determined the influence of the System-B plugger depth on filling adaptation. Fifty-six extracted human mandibular molars were instrumented using Profile NiTi rotary instruments, stratified based on curvature, then randomly distributed into two groups. Group 1 was obturated using the single-cone continuous-wave technique. Group 2 was obturated with a hybrid technique: lateral condensation followed by a continuous-wave down-pack. Based on System-B plugger penetration, teeth were divided into three subgroups: (a) < 3.5 mm, (b) 3.5 to 4.5 mm, and (c) > 4.5 mm. Roots were horizontally sectioned at 1 mm and 3 mm coronal to the apical foramen, stained, and photographed. Four evaluators scored the adaptation of gutta-percha to the prepared canal walls. In 100% (n = 56) of the samples, no statistically significant difference existed between the two obturation methods at 1-mm (x = 1.80, SD +/- 0.69) or 3-mm (x = 1.804, SD +/- 0.69) sections. Best results were obtained with a plugger depth 3.5 to 4.5 mm from the working length.

Gutta-Percha↗

PubMed2003

Comparison of apical transportation in four Ni-Ti rotary instrumentation techniques.

A new radiographic technique was used to compare apical transportation in four Ni-Ti rotary instrumentation sequences. Mesiobuccal canals of 60 extracted mandibular molars were randomly divided into four groups. Groups 1 and 3 were instrumented by crown-down and groups 2 and 4 by step-back technique with 0.06 ProFiles series 29 to size 6. In groups 3 and 4 Greater Taper files were first used in a crown-down manner. The central axes of initial and final instruments were radiographically superimposed to measure loss of working length (WL) and transportation at 0, 0.5, 1, 3, and 5 mm from WL. ANOVA test showed no significant differences among groups regarding degree of transportation or loss of WL. Transportation was negatively correlated with radius of curvature at 0.5 and 5 mm from WL. The results indicate that the operational sequence of ProFiles or preinstrumentation with GT files has no effect on degree of transportation and loss of WL.

Analysis of Variance↗

PubMed2002

Long-term follow-up of cases considered healed one year after apical microsurgery.

A previous report demonstrated 96.8% healing within 1 yr after apical surgery was performed with the surgical operating microscope and Super-EBA as the root-end filling material. The purpose of this paper is to report on the long-term follow-up of those cases that were considered healed at the short term. Clinical examinations were made and radiographs were evaluated 5 to 7 yr after the case had first been considered healed. Criteria for determining healed cases were the same as those used in the first report. Of the 59 roots evaluated, 54 (91.5%) remained healed, whereas 5 (8.5%) showed evidence of apical deterioration.

Dental Pulp Diseases↗

PubMed1993

Effects of capsaicin on KCl-induced blood flow and sensory nerve activity changes in the tooth pulp.

Potassium ion-containing solutions have been shown to initially excite then depress intradental nerve activity (INA) when applied into deep dentinal cavities. The INA reflects activity originating in intradental A fibers. Application of KCl to deep dentinal cavities also induces an increase in pulpal blood flow (PBF). Capsaicin is known to exert a highly selective desensitizing effect on polymodal C-fiber nerve endings. These C fibers are generally believed to release vasoactive substances in response to stimulation. In order to determine if KCl exerts its vascular effect via activation of capsaicin-sensitive nerve fibers, we examined blood flow and sensory nerve responses to KCl obtained before and after capsaicin desensitization. The A-fiber nerve activity was determined by using INA recording technique. Blood flow was measured simultaneously from the same tooth using laser Doppler flowmetry. Local application of 0.25 M KCl to a deep dentinal cavity induced a brief spike burst and an increase in PBF of 76.0 +/- 14.6% (n = 8). Repeated applications of 0.25 M KCl caused a consistent increase in the peak PBF amplitude (n = 8). Local application of 100 microM capsaicin to a deep dentinal cavity caused an increase in PBF of 116.8 +/- 26.3% (n = 8) lasting 12-18 min, but capsaicin application did not appear to evoke any INA response. The amplitude of PBF in response to capsaicin application declined during repeated applications. Following repeated applications of capsaicin the PBF response to KCl was significantly reduced (9.9 +/- 4.3%, n = 8).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1988

Effects of ionic and non-ionic solutions on intradental nerve activity in the cat.

Intradental nerve activity (INA) was recorded from cat canine teeth to determine whether solutions altering intradental nerve sensitivity were strongly correlated to the osmotic concentration of the solution or via a more direct action on intradental nerve excitability. The effects of various ionic and non-ionic solutions were tested in both deep and shallow dentinal cavities. With saline in the deep dentinal cavity a very low firing rate or resting nerve spike (action potentials) activity was recorded. When 3 M NaCl was placed in the same or similar cavity a high discharge rate of nerve spike activity was obtained. This 3 M NaCl elicited activity was utilized to determine the inhibitory or excitatory effects of various test agents on the intradental nerves. The following agents: MgCl2, MgSO4, and CaCl2 were inhibitory to the INA response elicited by 3 M NaCl. Non-ionic solutions of urea or sucrose failed to evoke INA and they were also minimally effective in altering 3 M NaCl elicited activity. Shallow cavities were utilized to maintain the tubular structure of dentin relatively intact. In the shallow cavity preparations hypertonic sucrose or urea failed to evoke INA, even when dentin was etched with 50% citric acid for 2 min. The results suggest that the osmolarity of these solutions is a poor indicator of the INA.

Animals↗