• Restorative Dentistry and Endodontics
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• v.12 no.1
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• pp.7-24
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• 1986

The purpose of this study was to observe the compressive strength, compressive fatigue strength, surface hardness, water sorption and solubility of eight different posterior restorative composite resins. Eight composite resins were tested for their strength of the compressive and compressive fatigue with prepared two different types of specimens (I and T-type) using a Instron universal testing machine (model No. 1332). The hardness was measured with a Knoop hardness tester (MVH-2, Tokyo) for each cylindrical specimen, 7mm in diameter and 5mm thick. The water sorption and solubility were evaluated with the prepared composite resin disks, 20mm in diameter and 1mm thick. The results were as follows: 1. The compressive strength, compressive fatigue strength and hardness were noticed to be Increased by increasing the volume content of filler. 2. The compressive strength was appeared to be independent on the type of specimen, but the compressive fatigue strength was found to be greatly influenced by the type of specimens. 3. The composite resins having higher compressive strength had also higher compressive fatigue limits. 4. The compressive fatigue limits at $10^5$ stress cycles were about 50-80% of the compressive strength and were showen to be dependent on the materials and type of specimens. 5. The larger the filler particle size was, the lower was the water sorption. And the water sorption of BIS-GMA resin was higher than that of urethane resin. 6. The visible light-cured composite resin had a higher value of solubility than the chemically- cured composite resin. And the solubility tended to decrease by increasing the volume content of filler.

• Restorative Dentistry and Endodontics
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• v.10 no.1
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• pp.135-144
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• 1984

This study was undertaken to evaluate the degree of the marginal leakage of composite restoration with 3 brands of dental adhesives by means of the dye penetration at the enamel and dentinal margins. 150 cavities of class V were prepared on the buccal and lingual surfaces of 75 extracted anterior and premolar teeth, which were devided into 3 groups. The cavities were filled with composite resin, Silar$^{(R)}$ (3M) and Heliosit$^{(R)}$ (Vivadent) after application of the dental adhesives, specifically Scotchbond$^{(R)}$ (3M) which is essentially composed with halophosphorus ester of Bis-GMA, Dentin Adhesit$^{(R)}$ (Vivadent) which is polyurethane resin, and Enamel Bond$^{(R)}$ (3M) which is a product of Bis-GMA with low viscosity at internal surfaces and margins of the cavities. All specimens were immersed in $37^{\circ}C$, 0.5% methylene blue solution for 24 hours after thermocycling at $4^{\circ}C$ and $60^{\circ}C$, embedded in acrylic resin, and sectioned with diamond disk into two parts. The sectioned specimens observed with the light microscope. The following results were obtained: 1. The group filled with Scotchbond$^{(R)}$-Silar$^{(R)}$ the other two groups at the enamel margins. 2. No significant difference in the degree of the marginal leakage had appeared between Dentin Adhesit$^{(R)}$-Heliosit$^{(R)}$ group an d Enamel Bond$^{(R)}$-Silar$^{(R)}$ group at the enamel margins. 3. Severe marginal leakage with penetration of dye to the floor of cavity had appeared from the all three groups and no significant difference in the degree of marginal leakage existed between the three groups at the dentinal margins.

• Restorative Dentistry and Endodontics
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• v.38 no.4
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• pp.241-247
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• 2013

Objectives: The aim of this study was to determine the effect of epigallocatechin gallate (EGCG) on the shear bond strength of composite resin to bleached enamel. Materials and Methods: Ninety enamel surfaces of maxillary incisors were randomly divided into 9 groups as follows: G1: control (no bleaching); G2: bleaching; G3: bleaching and storage for seven days; G4 - 6: bleaching and application of 600, 800 and 1,000 ${\mu}mol$ of EGCG-containing solution for 10 minutes, respectively; G7 - 9: bleaching and application of 600, 800 and 1,000 ${\mu}mol$ of EGCG-containing solution for 20 minutes, respectively. The specimens were bleached with 30% hydrogen peroxide gel and a composite resin cylinder was bonded on each specimen using a bonding agent. Shear bond strength of the samples were measured in MPa. Data was analyzed using the two-way ANOVA and Tukey HSD tests (${\alpha}$ = 0.05). Results: The maximum and minimum mean shear bond strength values were observed in G1 and G2, respectively. Time and concentration of EGCG showed no significant effects on bond strength of the groups (p > 0.05). Multiple comparison of groups did not reveal any significant differences between the groups except for G2 and all the other groups (p < 0.05). Conclusions: There is a significant decrease in bond strength of composite resin to enamel immediately after bleaching. A delay of one week before bonding and the use of EGCG increased bond strength of composite resin to bleached enamel.

• The Journal of the Korean dental association
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• v.11 no.5
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• pp.337-340
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• 1973

The authers have studied the marginal leakage on various filing materials : Composite resin, Polycarboxylate cement, Zinc phosphate cement, Silicate cement and Zinc-oxide eugenol cement, by means of penetration of 2% aquous methylene blue between cavity walls and filing materials at body temperature and at thermal changs in the range of 4~60℃ The results revealed as follows. 1) All the filling materials revealed the penetration of dye between cavity walls and filling materials. 2) Zinc-oxide eugenol cement was the most effective to prevent the dye penetration on the contrary silicate cement cases showed greatest leakage at 37℃ and at temperature changes in range of 4-60℃. 3) The composite resin showed moderate leakage either at 37℃ or at thermal changes 4) Marginal obstructions of polycarboxylate cement were unsatisfactory at 37℃ and at temperature changes.

• Restorative Dentistry and Endodontics
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• v.13 no.1
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• pp.151-158
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• 1988

The purpose of this study was to evaluate the effect of canal filling methods and post-space preparation time on the apical seal of endodontically treated teeth. Seventy-six single-rooted human teeth were divided into 6 groups and each tooth was obturated and prepared post-space according to the purpose of this study. After all specimens were immersed in Indian ink, decalcified and cleared, the degree of dye penetration into the root canals observed by magnifying glass (X20) and measured by caliper. The results were as follows: 1. In the thermatic condensation, no significant difference in ink penetration occured when the post-spaces were created immediately after obturation or when they were made a week later. 2. In the lateral condensation, no significant difference in ink penetration existed between teeth whose post-space were prepared immediately or delayed. 3. In comparison of experimental groups and control groups, no significant difference showed when the groups were obturated with McSpadden compactor but when the teeth were laterally condensed, the experimental groups showed less ink penetration than controls. 4. Thermatic condensed teeth with McSpadden compactor were less ink penetration thn laterally condensed teeth.

• Restorative Dentistry and Endodontics
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• v.8 no.1
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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.

• Restorative Dentistry and Endodontics
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• v.12 no.1
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• pp.77-84
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• 1986

This study was designed to compare the antimicrobial effect of the several root canal cements and to determine the duration of their activity. After Strep. sanguis 9811 was streaked on the surface of BHI agar and Plain agar, PVC tubes filled with root canal cements were applied and cultured for 48 hours, aerobically. Following results were obtained, 1. All of the examined root canal cements had antimicrobial activity with varying degree. 2. The antimicrobial activity of N2 was larger than any other root canal cements. Nogenol and Tubliseal showed the lowest activity. ZOE, AH26, Procosol and PCA cement showed the moderate antimicrobial activity. (P>0.05) 3. At one day after mixing the root canal cements, all of the root canal cements except N2 and PCA cement showed greatly reduced antimicrobial activity. 4. At three days after mixing, PCA cement showed the reduced antimicrobial activity. N2 showed the reduced activity at 7 days after mixing.

• Restorative Dentistry and Endodontics
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• v.43 no.3
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• pp.30.1-30.12
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• 2018

Objectives: To evaluate sealing ability of root canals obturated with bioceramic-impregnated gutta percha cone (BCC) or gutta percha (GP), with bioceramic sealer (BCS) or AH Plus (AH; Dentsply-Maillefer), in roundly-prepared canals using matched single-cone technique, based on bacterial leakage test, and to analyze obturation quality using micro-computed tomography (CT) analysis. Materials and Methods: Ninety-two distobuccal roots of maxillary molars were prepared using nickel-titanium files to apical size 40/0.06. The roots were divided into 4 groups (n = 20) that were obturated with a master cone and sealer: GP/AH, BCC/AH, GP/BCS, and BCC/BCS. Bacterial leakage model using Enterococcus faecalis was used to evaluate sealing ability for 60-day period. Obturated samples from each group (n = 4) were analyzed using micro-CT. Results: All groups showed bacterial leakage at 20%-45% of samples with mean leakage times of 42-52 days. There were no significant differences in bacterial leakage among the groups. Micro-CT showed minimal gaps and voids in all groups at less than 1%. Conclusions: In roundly-prepared canals, the single cone obturation with BCC/BCS was comparable to GP/AH for bacterial leakage at 60 days.

• Journal of Dental Anesthesia and Pain Medicine
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• v.17 no.1
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• pp.47-53
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• 2017

Background: Every patient who undergoes mandibular third molar surgery is concerned about post-operative pain. Indeed, previous researchers have used various methods to treat such pain. This study aimed to assess the effectiveness of sublingual injection of dexamethasone (8 mg) to treat post-operative pain after mandibular third molar surgery. Method: This was a randomized, double-blind, split-mouth, clinical trial, involving 48 healthy patients who required surgical removal of two mandibular third molars with similar bilateral positions. All operations were performed by the same experienced surgeon. The patients were randomized into a study group (8 mg dexamethasone injection) and a placebo group (normal saline injection). Both interventions were injected into the sublingual space immediately after local anesthesia, 30 min before the first incision. The study group received an 8 mg dexamethasone injection, while the placebo group received a normal saline injection. The wash period between the patients' two operations was 3 to 4 weeks. Pain was assessed by recording the number of analgesic tablets (rescue drug) consumed, as well as by noting the patients' responses to the visual analog scale (VAS) on the first, second, and third days after surgery. Results: The study group differed significantly from the placebo group in terms of VAS score and analgesic consumption. Conclusion: Dexamethasone (8 mg), injected sublingually, significantly eased post-operative pain after surgical removal of the mandibular third molar.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.40
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• pp.36.1-36.5
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• 2018

Background: Botulinum toxin-A (BTX-A) injection into muscle reduces muscular power and may prevent post-operative complication after orthognathic surgery. The purpose of this study was (1) to evaluate BTX-A injection into the masseter muscle on the prevention of plate fracture and (2) to compare post-operative relapse between the BTX-A injection group and the no injection group. Methods: Sixteen patients were included in this study. Eight patients received BTX-A injection bilaterally, and eight patients served as control. All patients received bilateral sagittal split ramus osteotomy for the mandibular setback and additional surgery, such as LeFort I osteotomy or genioplasty. Post-operative plate fracture was recorded. SNB angle, mandibular plane angle, and gonial angle were used for post-operative relapse. Results: Total number of fractured plates in patients was 2 out of 16 plates in the BTX-A injection group and that was 8 out of 16 plates in the no treatment group (P = 0.031). However, there were no significant differences in post-operative changes in SNB angle, mandibular plane angle, and gonial angle between groups (P > 0.05). Conclusions: BTX-A injection into the masseter muscle could reduce the incidence of plate fracture.