• Restorative Dentistry and Endodontics
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• 제8권1호
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• pp.123-131
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• 1982

The purpose of this study was to observe the responses of the remaining pulp tissue after pulpotomy upon the several kinds of $Ca(OH)_2$ products and the responses of periapical tissue upon some root canal filling materials after extirpation. For pulpotomy, the class V cavities were prepared on the premolars, molars and upper canines, and the pulp was amputated. Each drug was placed over the amputated tissue and cavity was sealed with zinc oxide eugenol cement. The drugs which were used for the study were Dycal (Caulk Co. U.S.A.), Cavitec (Kerr Co. U.S.A.), Calvital, Nobudyne and Neodyne (Neo Dental Chemical Products). For extirpation, the endodontic cavities were prepared on the lingual surfaces of anterior teeth, and the pulp tissues were extirpated as routine method. After enlarging, irrigation, and measuring of root length by taking X-ray, each root canal filling material was filled in the canal with gutta percha cone, and endodontic cavity was sealed with zinc oxide eugenol cement. Zinc oxide eugenol, $Ca(OH)_2$ (Eli Lilly Co. U.S.A.) and Vitapex (Neo Dental Chemical Products) were used as root canal filling materials. Animals were sacrificed after 1, 3 and 6 weeks following the operation. The teeth were decalcified in formic acid, sectioned and stained with hematoxylin eosin. Microscopic examination revealed as follows. 1. Dycal: The dentin bridge formation was observed at the 3rd week after pulpotomy. Inflammatory conditions which were infiltration of inflammatory cells and dilatation of blood vessels were kept in remaining pulp tissue at the 6th week. 2. Calvital: The dentin bridge was observed at the 1st week after pulpotomy. As the time clasped, the pulp tended to be the fibrous degeneration. 3. Cavitec, Nobudyne and Neodyne: In the case of Cavitec and Nobudyne, the incompleted and irregular dentin bridge was observed at the 6th week, and in Neodyne, was observed at the 3rd week. The severe inflammatory changes were seen in the remaining pulp tissue. As the time clasped, the fibrous degeneration tended to spread in the remaining pulp tissue. 4. $Ca(OH)_2$: Osteocementum was formed at the 3rd week, the matrix of cementum and dentin were resorted, and infiltration of lymphocytes was seen in periapical tissue when $Ca(OH)_2$ was used as canal-filling materials. S. ZOE and Vitapex The cementum like substance was seen in periapical portion at the 1st week, when ZOE and Vitapex were used as root canal filling materials. As the time elapsed, the matrix of cementum and dentin tended to be resorted. At the 6th week, the inflammatory condition of periapical tissue was continued in the case of ZOE, but was reduced in the case of Vitapex.

• 대한치과보철학회지
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• 제31권4호
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• pp.468-481
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• 1993

The Purpose of this study was to analyze the stresses and displacements of various post and core. The Finite element models of central incisors were divided into seven types according to the various amount of remaining tooth structures. $10kgf/mm^2$ force was applied respectively as follows : 1) Horizontal on the labial surface 2) $26^{\circ}$ diagonal direction on the lingual surface. Material property, geometry, and load condition of each model were inputted to the two dimensional ANSYS 4.4A finite element program : stresses and displacements were analyzed. Results were follows : 1. In the case of $130^{\circ}$ shoulder post and core, Maximum tensile and shear stresses were observed in the crown margin. 2. Maximum shear stress was about 29% reduced by contrabevel. 3. In the case of 1mm axial tooth structure, Maximum tensile stress observed in the dentin. 4. In the case of but joint of cervix, Maximum stress concentration was observed in the dentin by the inclined and horizontal force. 5. Horizontal force produced the extraordinary high stresses in dentin and supporting structures. 6. The amount of remaining tooth structure affected the level of stress significantly and it determined the location of stress concentration.

• Journal of Periodontal and Implant Science
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• 제31권1호
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• pp.21-41
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• 2001

The goal of Periodontal treatment is predictable periodontal regeneration. But until now, many products including GTR materials and growth factors are beyond of complete regeneration. BMP can induce ectopic bone formation when implanted into sites such as rat muscle and can greatly enhance healing of bony defects when applied exogenously. BMP can promote periodontal regeneration by their ability to stimulate new bone and new cementum formation. But little is known about optimal conditions required for the application. Root conditioning is used for bioacive root change so altered root surface provides a substrate that promotes chemotaxis, migration and attachment of peridontal cells encouraging connective attachment to the denuded root surface. The aim of this study is to investigate whether the acid conditioning change effect of rhBMP-2 on human periodontal ligament cell and osteoblast cell line. 288 periodontally involved root dentin slices are divided into 6 groups, each 48, 1)control, 2)treated with BMP, 3)treated with citric acid 4)treated with citric acid+BMP 5)treated with tetracycline 6)treated with TC+BMP. Each group was devided half, so 12 root dentin slices were seeded with periodontal ligament cells and 12 were seeded with osteoblasts. At day 2 and 7, cell number, protein assay, ALP activitiy was measured. To investigate morphology of cultured cells, SEM was employed. Statistical analysis was performed with SPSS 8.0 either t-test or ANOVA test. The results are ; Protein assay and cell number was slightly decreased in CA+BMP group compared to Ca group but it was not statistically significant and ALP activity was much more increased in CA+BMP group compared to CA group so there was no statistically significance between BMP and CA+BMP group and statistically significant compared to control group. Cell number and protein assay was slightly increased in TC group and ALP activity was much less the BMP group and CA group. Cell number and protein and ALP activity was not much increased in TC+BMP group. TC group and TC+BMP group showed cell morphology change in SEM. This results suggested that application of root surface with citric acid before BMP treatment might give better result in periodontal regeneration.

• 대한치과기공학회지
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• 제46권1호
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• pp.15-19
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• 2024

An ideal post material should have physical properties similar to those of dentin. Post materials with high elastic moduli may cause root fractures. This clinical report describes the treatment of a severely damaged tooth using a recently introduced material. Polyetherketoneketone (PEKK) is a semicrystalline high-performance thermoplastic polymer. PEKK is a promising material for custom post-and-core fabrication because of its elasticity close to that of dentin, good shock absorbance, machinability, and low cost. A laboratory scanner was used to digitize the conventional impression of a severely damaged maxillary right first molar. A custom PEKK post-and-core was designed and milled using computer-aided design and computer-aided manufacturing technology. Using the proposed technique, a custom PEKK post-and-core was fabricated accurately and human error was reduced. Restoration was luted with resin cement. Custom PEKK post-and-core restorations are a viable alternative for treating severely damaged teeth.

• Journal of Periodontal and Implant Science
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• 제32권2호
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• pp.303-314
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• 2002

This study was performed to evaluate the usability of Er:YAG laser for periodontal therapy. Forty dental root slabs ($5{\times}5{\times}2mm^3$) were prepared from human periodontally diseased extracted teeth and grouped into 4 groups: 1) control (root planing only), 2) root planing and irradiated with laser at 30mJ, 3) root planing and irradiated with laser at 60mJ, and 4) root planing and irradiated with laser at 100mJ. The root slabs were embedded in resin block before laser treatment. Er:YAG laser was irradiated under water irrigation with the tip held perpendicular to the root surface in contact mode. After Er:YAG laser irradiation or planing on the root surface, morphological changes have been observed under SEM, and the micro-hardness and Ca/P ratio were compared. 1. In the Control group, the root surface showed the directional change caused by root planing instrumentation, and the presence of smear layer, and no exposure of dentinal tubule was observed. Laser irradiated group showed surface changes with rough dentin surface of niche and depression and dentinal tubule exposure by the elimination of smear layer. 2. The micro-hardness of root surface in the laser irradiated group was higher than the control group. The higher energy output was applied, the higher micro-hardness on root surface was resulted. 3. The higher energy output was applied, the higher Ca/P ratio was observed. The higher Ca/P ratio in 60mJ group and 100mJ group was statistically significantly compared to the control group and the 30mJ group. These results suggest that Er:YAG laser irradiation on the periodontally diseased root surface could remove smear layer and increase the micro-hardness on root surface and Ca/P ratio which contribute to enhance the acid resistance of periodontally treated root surface.

• 대한치과보존학회:학술대회논문집
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• 대한치과보존학회 2003년도 제120회 추계학술대회 제 5차 한ㆍ일 치과보존학회 공동학술대회
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• pp.616-616
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• 2003

Recently root caries is reported as an increasing oral disease. Many reserchers studied in vivo and in vitro enamel lesions but due to its perticular structure and different chemical composition compared to the enamel, little effort has been made to root caries study. The purpose of this study is to compare and to evaluate the effects of the degree of saturation on the progression of artificial root caries lesion. A total of 8 human premolars without any defects and cracks were selected and were removed cementum and were cleaned with ultrasonic device and pumice without fluoride.(omitted)

• Restorative Dentistry and Endodontics
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• 제21권1호
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• pp.300-310
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• 1996

Recently, there have been attempts to obstruct the dentinal tubules and remove the smear layer by way of laser irradiation in the root canal during endodontic treatment. This treatment was designed to make the root canal to be nonporous. Using 33 extracted single rooted teeth, 30 teeth were divided into 3 groups (10 each), and 3 teeth were used as samples for SEM. Using Nd : YAG laser, the control group was not irradiated, experimental group l(1W group) was irradiated with 1W, 15pps, 15sec., 3 times, 6.7mJ and experimental group 2(3W group) was irradiated with 3W, 15pps, 15sec., 3 times 20mJ. Thereafter the roots were immersed in methylene blue for 8 hours, and the dye infiltration pattern was observed under stereomicroscope and canal wall surface change was observed under SEM. The results are as following ; 1. As a result of evaluating the dye infiltration rate of the apical and middle 1/3, there was significant difference between control group and 1W group, control group and 3W group and there was no significant difference between 1 W group and 3W group. 2. In each group, as a result of comparing the dye infiltration rate of the apical and middle 1/3, there was no significant difference in control and 1W group but significant difference in 3W group. 3. In the control group smear layer was scarecely found and many dentinal tubules were found to be open. 4. In the 1W group, the number of dentinal tubules were decreased and gradual changes of the dentin surface could be seen and 3W group, almost no dentinal tubules could be found and the dentin surface was changed a little more and showed signs of partial fusion.

• Restorative Dentistry and Endodontics
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• 제13권1호
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• pp.103-111
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• 1988

The purpose of this study was to, examine the sealing ability of the denting bonding agent, when used with gutta percha cone, as a root canal sealer. Seventy two upper and lower extracted human teeth with single root were randomly selected and instrumented in a conventional method with K-file. After instrumentation and dry the canal with paper point, there were divided into three groups and twenty four teeth in each group were filled with the following material; In group I: Scotchbond in combination with gutta percha cone. In group II: AH 26 in combination with gutta percha cone. In group III: Tubli-Seal in combination with gutta percha cone. All specimens were immersed in Indian Ink, decalcified, and cleared. The depth of dye penetration into the canals were evaluated by caliper at the intervals of 1 day, 1 week, 2 weeks. The results were as follows; 1. Depth of dye penetration for all groups increased with time. 2. As to difference in mean dye penetration at time interval of 1 day and 14 days, Scotchbond group exhibited the smallest value as 0.53mm and Tubli-Seal group exhibited the largest value as 0.70mm. 3. There was the difference of dye penetration between each group, but its difference was not significant, statistically.

• Restorative Dentistry and Endodontics
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• 제18권1호
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• pp.205-213
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• 1993

The purpose of the study was to evaluate the degree of the marginal leakage of esthetic restorative materials on root caries restoration. 120 cavities were prepared to $90^{\circ}$ butt joint on all margins on the crown and root portion, and divided into 4 groups. The four groups of cavity were filled with Amalgam(Dongmuyung Dental Alloy Co., Ltd, KOREA), Silux$^{(R)}$(3M Co., USA)-Scotch Bond 2$^{(R)}$(3M Co., USA), Silux$^{(R)}$-All Bond$^{(R)}$(BISCO USA), and GC Fuji II$^{(R)}$(G-C Co., JAPAN) respectively. The apical margin of the preparation was finished to leave a flash of restorative material. The coronal margin of the preparation was finished not to leave a flash of restorative material. All specimens were sectioned longitudinally with Isomet Low speed saw(Buether Ltd, USA). The degree of dye penetration was evaluated as the parameter of marginal leakage under the stereoscope. The results were as follows. 1. At the enamel and dentin/cementum margins, the margin were finished to leave a flash of material showed less marginal leakage than that were finished not to leave a flash of material (P<0.001). 2. The enamel margins showed less marginal leakage than the dentin/cementum margins(P<0.001). 3. There was no significant difference in the degree of the marginal leakage between Silux$^{(R)}$-Scotch Bond 2$^{(R)}$ group and Silux$^{(R)}$-All Bond$^{(R)}$ group.

• Restorative Dentistry and Endodontics
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• 제44권3호
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• pp.25.1-25.10
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• 2019

Objective: The aim of this study was to evaluate discoloration of teeth undergoing regenerative endodontic procedures (REPs) using blood clot or platelet-rich fibrin (PRF) as the scaffolds and different calcium silicate-based materials as the intracanal coronal barriers in an ex vivo model. Materials and Methods: Forty-eight bovine incisors were prepared and disinfected using 1 mg/mL double antibiotic paste (DAP). The specimens were then randomly divided into 2 groups (n = 24) according to the scaffolds (blood or PRF). After placement of scaffolds each group was divided into 2 subgroups (n = 12) according to the intracanal coronal barriers (ProRoot MTA or Biodentine). The pulp chamber walls were sealed with dentin bonding agent before placement of DAP and before placement of scaffolds. The color changes (${\Delta}E$) were measured at different steps. The data were analyzed using 2-way analysis of variance. Results: Coronal discoloration induced by DAP was not clinically perceptible (${\Delta}E{\leq}3.3$). Regarding the type of the scaffold, coronal discoloration was significantly higher in blood groups compared with PRF groups at the end of REP and after 1 month (p < 0.05). However, no significant difference was found between PRF and blood clot after 6 months (p > 0.05). Considering the type of intracanal coronal barrier, no significant difference existed between ProRoot MTA and Biodentine (p > 0.05). Conclusions: With sealing the dentinal tubules of pulp chamber with a dentin bonding agent and application of DAP as an intracanal medicament, coronal color change of the teeth following the use of PRF and blood sealed with either ProRoot MTA or Biodentine was not different at 6-month follow-up.