• Restorative Dentistry and Endodontics
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• 제15권1호
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• pp.1-15
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• 1990

The aim of this study was to investigate the effect of dental therapeutic agent on conduction velocity and threshold current of intradental A- and C-fibers in the cat. Inferior alveolar nerve of cat anesthetized with sodium pentobarbital was exposed and dissected until response of functional single pulp nerve until could be evoked by monopolar electrical stimulation of the crown of the lower left canine teeth. 10ms rectangular pulse was used to determine the threshold current and 1ms rectangular pulse was used to determine conduction velocity. After application of calcium chloride (1, 2, 6M), calcium hydroxide mixed with saline, potassium chloride (0.2, 0.8, 1.6M), eugenol, zinc oxide eugenol to the cavity on the labial surface, conduction velocity and threshold current of single pulp nerve unit were compared with the control. In 10 cats, 24 $A{\delta}$- and 11 C- pulp nerve units were recorded. The mean conduction velocities of $A{\delta}$- and C-fibers were 7.5m/sec (SD=5.8) and 1.2m/sec (SD=0.4), respectively. The mean threshold current was $12.3{\mu}A$ (SD=5.3) for $A{\delta}$-fibers and $24.9{\mu}A$ (SD=8.1) for C-fibers. 1, 2, 6M calcium chloride caused decrease of conduction velocity and remarkable increase of threshold current in $A{\delta}$- and C-fibers. The effect of calcium hydroxide mixed with saline was similar but smaller than calcium chloride solution. 0.2M potassium chloride had insignificant effect. In 0.8M potassium chloride, the threshold current was increased although conduction velocity was not affected. In 1.6M potassium chloride, the threshold current was increased and the conduction velocity was slowed down. Spontaneous activity was recorded frequently for first 5 min but gradually reduced both in $A{\delta}$- and C-fibers. Eugenol had irreversible effect on pulp nerve in that initially there were not certain changes in the conduction velocity and threshold current of $A{\delta}$- and C-fibers, but the responses to electrical stimulation were abruptly disappeared after sustained application and were not recovered. Contrary to eugenol, zinc oxide eugenol did not caused significant increase of the threhold current and caused time dependent decrease of the conduction velocity, and did not show any irreversible change.

• 대한소아치과학회지
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• 제36권1호
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• pp.91-95
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• 2009

소아 및 청소년에서 유구치 및 대구치는 인접면이나 평활면에 광범위한 치아우식증으로 치질이 많이 파괴되거나, 치수치료로 인하여 치질 부위가 약해져서 파절되기 쉬운데, 치료방법으로 기성금속관이 사용되고 있다. 기성금속관은 1950년대 Humphrey에 의해서 소개되었고, 장점으로 내구성이 강하고, 임상적 수명이 길며, 성공률이 높지만, 치질 삭제로 인한 치수노출 위험성과 인접 치아의 삭제의 가능성이 있고, 다수의 치아 수복 시에 교합면 높이를 맞추기 어려우며, 큰 크기의 기성금속관을 선택한 경우 금속관의 변연에 의해 인접 치아의 맹출을 방해할 수 있다는 단점이 있다. 기성금속관의 단점을 보완하기 위한 방법으로 구치부 수복 시 교정용 밴드를 사용하는 것을 고려해 볼 수 있는데, 치아우식증으로 파괴된 치질 부위를 교정용 밴드와 복합레진, 또는 글래스아이오노머, 아말감 등으로 수복하는 방법이다. 교정용 밴드를 이용한 구치부 수복은 치경부와 교합면에 치아우식증이 있어 치질이 많이 파괴되거나, 치수치료한 치아, 법랑질 저형성된 대구치 등에서 사용될 수 있고, 시술 시간이 짧아 행동조절이 어려운 어린이에서 유용하다. 그러나, 치료 후 구강위생상태를 청결히 유지시키는 것이 중요하다. 이 증례들에서는 유구치와 대구치에 광범위한 치아우식증의 치료를 위해 내원한 환아에서 교정용 밴드를 이용한 보존적 수복치료를 시행하여 양호한 결과를 보여 이를 보고하는 바이다.

• Restorative Dentistry and Endodontics
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• 제23권1호
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• pp.20-42
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• 1998

The present study was designed to understand the basic principles of the laser system and to assess the optimal coditions of the Nd:YAG laser irradiation system in order to expand the use of the laser system in the dental field. The laser system used in this study was a pulsed-wave output type and the power level is 9 watts. The incisors of developing rats were irradiated with the laser system explained above for 0.5, 1, and 2 seconds giving energy density 71, 167, and 215 J/$cm^2$ respectively. The rats were sacrificed just after irradiation or 10 minutes and 10 days after irradiation. The specimens were examined with the stereoscope, light microscope and transmission electron microscope. The results are as follows: 1. The tissue removal efficiency (depth of the cavity formed) is increased with the energy density after Nd:YAG laser irradiation. 2. The carbonized area is increased with the energy density. Cracks and melted appearance are seen in all kinds of the energy densities. 3. The lacunae in the damaged alveolar bone by the laser irradiation were empty, while those in the newly formed bone were occupied with the osteocytes. The damaged alveolar bone was repaired by the osteoblasts and macrophages on the periphery of the bone matrix. 4. The damaged enamel was replaced by the loose connective tissues showing many kinds of cells. The ameloblasts were differntiated on the replaced loose connective tissue. 5. The damaged dentin was repaired by the irregular dentin formed by the odontoblasts differentiated from the mesenchymal cells migrated from the pulp core.

• Restorative Dentistry and Endodontics
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• 제1권1호
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• pp.8-10
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• 1975

This study is to determine or detect deposition of mercury particles emitted from dental amalgam fillings. Amalgam fillings were carried out routinely on the dogs' teeth. (CIV cavities) Mercury which contains about 200${\mu}Ci$ of $^{197}Hg$ was employed on this purpose in each cavity. Radioactivity was measured by means of well type scintillation counter from saliva and mucous membrane of surrounding tissue. The C. P. M. value from the saliva was highest, mucous membrane was moderate and least on blood and fecs, as shown table on I. II. III. IV. 1. C.P. Mvalue from Saliva reveals 114 to 135 (lowest and highest) throughout the measuring period until 41 hours. 2. From blood samples no significant value was found. 3. CPM value from feces at2nd day and 4th day was about 90. 4. The highest and lowest CPMvalue from marginal gingiva was 465 and 209 respectively. Palatine showed 281 and 189, esophagus 179 and 165, and pulp from experiment tooth 190 and 104 respectively.

• Restorative Dentistry and Endodontics
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• 제39권2호
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• pp.120-125
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• 2014

Use of an apical plug in management of cases with open apices has gained popularity in recent years. Biodentine, a new calcium silicate-based material has recently been introduced as a dentine substitute, whenever original dentine is damaged. This case report describes single visit apexification in a maxillary central incisor with necrotic pulp and open apex using Biodentine as an apical barrier, and a synthetic collagen material as an internal matrix. Following canal cleaning and shaping, calcium hydroxide was placed as an intracanal medicament for 1 mon. This was followed by placement of small piece of absorbable collagen membrane beyond the root apex to serve as matrix. An apical plug of Biodentine of 5 mm thickness was placed against the matrix using pre-fitted hand pluggers. The remainder of canal was back-filled with thermoplasticized gutta-percha and access cavity was restored with composite resin followed by all-ceramic crown. One year follow-up revealed restored aesthetics and function, absence of clinical signs and symptoms, resolution of periapical rarefaction, and a thin layer of calcific tissue formed apical to the Biodentine barrier. The positive clinical outcome in this case is encouraging for the use of Biodentine as an apical plug in single visit apexification procedures.

• Imaging Science in Dentistry
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• 제50권3호
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• pp.183-192
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• 2020

Purpose: This study was performed to assess the accuracy of preoperative cone-beam computed tomography (CBCT), when justified for other reasons, in locating the apical foramen and establishing the working length. Materials and Methods: Six electronic databases were searched for studies on this subject. All studies, of any type, were included if they compared measurements of working length with preoperative CBCT to measurements using an electronic apex locator (EAL) or histological reference standard. Due to the high levels of heterogeneity, an inverse-variance random-effects model was chosen, and weighted mean differences were obtained with 95% confidence intervals and P values. Results: Nine studies were included. Compared to a histological reference standard, CBCT indicated that the apical foramen was on average 0.40 mm coronal of its histological position, with a mean absolute difference of 0.48 mm. Comparisons were also performed to an EAL reference standard, but the conclusions could not be considered robust due to high levels of heterogeneity in the results. Conclusion: A low level of evidence is produced suggesting that preoperative CBCT shows the apical foramen to be on average 0.40 mm coronal to its histological position, with a mean absolute difference of 0.48 mm.

• 대한소아치과학회지
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• 제23권4호
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• pp.775-787
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• 1996

The purpose of this study was to investigate the postnatal development of pulpal innervation with the tooth development and eruption process in developing rat mandibular molars (postnatal 1, 5, 10, 15, 20, 25, 35day-old and adult rats). Immunohistochemical method was carried out for the detection of nerve fibers, using the antibody against calcitonin gene-related peptide(CGRP). The results were as follows: The feature of CGRP-IR nerve fibers were shown in a bead-like appearance. The time of nerve entering into the dental papilla of tooth follicle began at the occured advanced dentinogenesis. The development of Raschkow plexus began at the formative stage of the roots and was accelerated at the stage of the crown emerged into the oral cavity. The number of nerve fibers entering the odontoblastic layer increased with the tooth eruption and mastication. The development of innervation was shown to be related with the stage of the development of individual teeth rather than the chronological age of the rat.

• Restorative Dentistry and Endodontics
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• 제13권1호
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• pp.53-67
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• 1988

An investigation was carried out to compare the pulp responses against a few type of composite and streptococcus mutans contamination under the zinc oxide eugenol cement, and also confirmed pulpal responses of various composites with or without base. Seventy eight teeth from 6 dogs were employed and divided into 6 groups. Class V cavities were prepared on each tooth routinely with low speed dental engine. Paper disc about 0.3mm thick was immersed in the BHI broth in which streptococcus mutans had been enriched and the disc was inserted on the cavity floor prior to filling. Scotch bond puls Silux as Bis-GMA system composite resin and Helimolar as urethane system composite resin were adopted. Control group: Zinc-Oxide Eugenol cement filling Experimental groups: Group 1. Scotch bond + Silux filling with Dycal base Group 2. Heliomolar filling with Dycal base Group 3. Scotch bond + Silux filling without base Group 4. Heliomolar filling without base Group 5. Streptococcus mutans application. All cavities were sealed with thick ZOE cement to avoid marginal leakage. Postoperative intervals of 1, 2, 3, 4, 5 and 6 weeks teeth were carefully extracted, processed and stained with Hematoxylin and Eosin. The results were as follows: 1. S. mutans application group and composites without any base showed more severe pupal response than control group and dyca based groups. 2. The experimental group of S. mutans application showed severe response in the early stage compared to the two groups of composite resin without base, but no significant difference was found following periods. 3. The difference of pulpal response is not significant between Bis-GMA system and urethane system. 4. Streptococcus mutans application group and composites without base groups showed the evidence of histologic recovery at the six week cases and the large amount of reparative dentin was the prominent feature. 5. Pulp responses against every material were inclined to normal according to the time elapsed.

• 대한치과보존학회:학술대회논문집
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• 대한치과보존학회 2001년도 춘계학술대회
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• pp.247-251
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• 2001

;A dental developmental anomaly is defined as an isolated aberration in tooth form, caused by a disturbance or abnormality which occurred during tooth development. There are numerous types of dental anomalies, and a considerable variation in the extent of the defects occurs with each type. Teeth with these anomalies pose unique challenges. Since the defects are not always apparent clinically, they can confuse diagnosticians investigating the etiology of pulpal pathosis. When endodontic treatment is required, the defects often hinder access cavity preparation and canal instrumentation. Treatment planning also becomes more challenging, since the defects can create complicated periodontal problems, and the malformed teeth can be difficult to restore, particularly those weakened by endodontic therapy. Fusion is defined as the joining of two developing tooth germs resulting in a single large tooth structure. The incidence of fusion is < 1% in the Caucasian population, and it is believed that physical force or pressure produces contact of the developing teeth. Clinically and radiographically, a fused tooth usually appears as one large crown with at least partially separated roots and root canals. There may be a vertical groove in the tooth crown delineating the originally separate crowns. Dens invaginatus is a deep surface invagination of the crown or root that is lined by enamel. Teeth in both maxillary and mandibular arches may be affected, but the permanent maxillary lateral incisor is the tooth most commonly involved. Studies have revealed an incidence ranging from 0.25% to as high as 10%. The invagination ranges from a slight pitting to an anomaly occupying most of the crown and root. The invagination frequently communicates with the oral cavity, allowing the entry of irritants and microorganism either directly into pulpal tissues or into an area that is deparated from pulpal tissues by only a thin layer of enamel and dentin. This continuous ingress of irritants and the subsequent inflammation usually lead to necrosis of the adjacent pulp tissue and then to periapical or periodontal abscesses. If the invagination extends from the crown to the periradicular tissue and has no communication with the root canal system, the pulp may remain vital. Recommended treatment of fused tooth and dens invaginatus has been reported in the endodontic literature. This case report describes the endodontic treatment of a maxillary laterl incisors having fused crown and dens invaginatus.natus.

• Imaging Science in Dentistry
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• 제45권4호
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• pp.221-226
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• 2015

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.