• Restorative Dentistry and Endodontics
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• v.15 no.1
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• pp.57-66
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• 1990

The author conducted a dental survey of college girl students and compared with that of college students 20 years and 10 years ago which based on the same criteria. The items of this survey included the prevalence of dental caries, DMFT and the kinds of restored materials. College girl students 2,294 were examined in May 1988, with the recommended criteria and method of W.H.O.. Among them, the data of 2,243 were analyzed and compared with the data of 1968 and 1978. The following results were obtained : 1. The average number of present teeth was $28.86{\pm}1.65$, which does not show much difference when compared to $29.00{\pm}1.94$ of 1968 and $28.97{\pm}1.64$ of 1978. 2. The prevalence of dental caries was 86.22%, which increased in comparison to 83.25% of 1968 and 84.92% of 1978. 3. DMF index was 19.98, which considerably increased in comparison to 14.56 of 1968 and 15.51 of 1978. 4. The number of DMFT was $5.75{\pm}5.04$ per student. Compared to $4.23{\pm}3.88$ of 1968 and $4.49{\pm}3.69$ of 1978, there is a considerable increase. I) The average number of decayed(D) teeth was $1.14{\pm}1.63$, which decreased from $1.16{\pm}1.57$ of 1968 and $2.09{\pm}2.16$ of 1978. II) The average number of missing(M) teeth was $0.23{\pm}0.73$, which also decreased from $0.69{\pm}1.11$ of 1968 and $0.32{\pm}0.79$ of 1978. III) The average number of filled(F) teeth was $4.39{\pm}4.91$, which increased from $2.38{\pm}3.33$ of 1968 and $2.09{\pm}3.17$ of 1978. 5. According to the analysis of filling material, filling baby including amalgam, gold inlay, resin, silicate cement and paladium inlay was 90.5%, which increased in comparison to 72.8% of 1968 and 83.6% of 1978. Among them, amalgam occupied 62.93%, which showed the most increase. On the other hand, crown and bridge was 6.5%, 3.0%, respectively, which showed continuous decrease from 12.1%, 15.1% of 1968 and 8.7%, 7.7% of 1978. Therefore, the prosthodontic treatment reduced due to the decrease of tooth extraction. In contrast, there is continuous increase of conservative treatment which maintaining natural tooth.

• Restorative Dentistry and Endodontics
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• v.31 no.6
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• pp.415-426
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• 2006

In this study, the changes in the degree of conversion (DC) and the microtensile bond strength (MTBS) of self-etching adhesives to dentin was investigated according to the time after curing. The MTBS of Single Bond (SB, 3M ESPE, USA), Clearfil SE Bond (SE, Kuraray, Japan), Xeno-III (XIII, Dentsply, Germany), and Adper Prompt (AP, 3M ESPE, USA) were measured at 48h, at 1 week and after thermocycling for 5,000 cycles between 5$^{\circ}$C and 55$^{\circ}$C. The DC of the adhesives were measured immediately, at 48h and at 7 days after curing using a Fourier Transform Infra-red Spectrometer. The fractured surfaces were also evaluated with scanning electron microscope. The MTBS and DC were significantly increased with time and there was an interaction between the variables of time and material (MTBS, 2-way ANOVA, p = 0.018; DC, Repeated Measures ANOVA, p < 0.001). The low DC was suggested as a cause of the low MTBS of self-etching adhesives, XIII and AP, but the increase in the MTBS of SE and AP after 48h could not be related with the changes in the DC. The microscopic maturation of the adhesive layer might be considered as the cause of increasing bond strength.

• Restorative Dentistry and Endodontics
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• v.24 no.4
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• pp.546-553
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• 1999

In Older to evaluate the effectiveness of 'One-bottle dentin adhesive system', the shear bond strengths of two fourth generation dentin adhesive systems and two One-bottle systems to the occlusal dentin of the freshly extracted third molars were measured by the regulation of the ISO TR 11405. The fourth generation dentin adhesive systems used in this study were Scotchbond Multi-Purpose Plus and All-Bond 2, and the One-bottle systems were Single Bond and One-Step. The effects of the thickness of hybrid layer and adhesive layer, the diameter of resin tag and the ratio between the diameter of resin tag and that of dentinal tubule were analyzed as the contributing factors of the shear bond strength of dentin bonding systems from the Scanning Electron Microscopic images. The results were as follows: 1. The shear bond strengths of Scotchbond Multi-Purpose, All-Bond 2, and Single Bond were 16.98${\pm}$3.40 MPa, 15.10${\pm}$2.77 MPa and 15.05${\pm}$3.18 MPa, respectively. There were no statistical differences(p>0.05). 2. But, the shear bond strength of One-Step were significantly lower than those of the other groups (11.81${\pm}$1.95 MPa, p<0.05). 3. The thicknesses of hybrid layer and adhesive layer of One-Step were significantly thinner than those of the other groups(p<0.05). The differences of the diameter of resin tag(p=0.0685) and the ratio between the diameter of resin tag and that of dentinal tubule(p=0.2401) were not significant among all the material groups. 4. The thickness of hybrid layer and adhesive layer might be considered as contributing factors of the she at bond strengths of dentin bonding systems, but the diameter of resin tag and the ratio between the diameter of resin tag and that of dentinal tubule might not.

• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.1
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• pp.1-10
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• 2002

The purpose of this study was to evaluate the fluoride release and anticariogenic effect of two compomers which is known to have been developed to improve the weak properties of glass ionomer cement and composite resin. Z-100 as composite resin(Group I), Dyract AP(Group II) and F-2000(Group III) as compomer, and Fuji II LC as glass ionomer cement(Group IV) were used as test materials and evaluations were peformed by pH/ISE meter far analyses of fluoride and polarizing microscope for analyses of anticariogenicity. The results can be summarized as follows: 1. The amount of fluoride release in compoite resin and compomer groups showed general pattern of decline during test period. Z-100 showed no fluoride release during test period. Fuji II LC showed the highest fluoride release among test groups and then F-2000 were followed. 2. The least resistance to dimineralization was observed microscopically in Z-100 group which has no fluoride in it. The best resistance to dimineralization was observed microscopically in Fuji II LC group and then compomer groups were followed. 3. Significant difference in lesion area was found between Fuji II LC group and another groups. Significant difference in lesion area was found between compomer groups and Z-100 group. No significant difference in lesion area was found between Dyract AP group and F-2000 cup. 4. Two compomers showed continual fluoride release and anticariogenic effect around filling materials. therefore, compomer was evaluated very attractive restorative material in pediatric dentistry.

• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.3
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• pp.362-370
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• 2002

During the last two decades, many new filling materials and material groups have been developed. the number of available restoratives has increased dramatically, especially during the last 5 years. Ormocers are a new class of materials which are still under development with regard to dental applications. However, in the chemical literature these materials have been known for a long time and used for producing scratch resistant coatings on plastic spectacle lenses. It is a combination of inorganic and organic materials. 'Ormocer' is an abbreviation for 'Organically Modified Ceramics'. These compounds are also known in the literature as 'Ormosils' (organically modified silicates). Their chemistry is comparable to that of silicones and organic polymers. The purpose of this study was to determine of compressive strength and flexural strength of a ormocer (Admira) and to investigate the effects of water absorption in comparison with three composite resins(Z-100, Tetric Ceram, Surefil) and one compomer(Dyract AP). The following results were obtained ; 1. Admira had the lower compressive strength than Surefil, but no statistically difference with other materials at 1 day(p>0.05). 2. Admira had the lower flexural strength than all other materials at 1 day. From 2 days, Admits showed lower flexural strength than three composite resin(p<0.05). 3. There was not statistically significant difference of compressive and flexural strengths between hybrid composite resin group(Z-100, Tetric Ceram) and Packable resin group(Surefil) for experimental period(30 days)(p>0.05). 4. All five materials showed an increase in compressive and flexural strength till 2 days and showed a decrease from 7 days in water(p<0.05). 5. Each materials had the statistically similar behavior of compressive and flexural strengths over time(p>0.05).

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.2
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• pp.119-124
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• 2009

Statement of problem: The increasing demand for esthetic restorations has been required developing new materials for tooth colored restoration. Ceromer(Ceramic Optimized Polymer) has some advantages over porcelain, and has gained increasing popularity in restorative dentistry. However, there is little information on the dimensional changes in a clinical restoration in moist conditions. Purpose: This study examined the dimensional changes in Ceromer restorations with a clinical crown shape that were fabricated in a clinical manner. Material and methods: The crowns for the maxillary central incisor were fabricated with two Ceromers($BelleGlass^{(R)}$ and $Targis^{(R)}$) using a similar clinical restoration manufacturing technique. A total of twenty specimens were prepared and immersed in distilled water at room temperature to allow for water absorption. The weight, height and width were measured at 24, 72 and 168 hours. The accumulated ratios of the changes were calculated and evaluated using a paired t-test and an independent independent t-test. Results: The dimensions and weight increased with increasing soaking time. $Targis^{(R)}$ showed significant differences in height and weight between 24 hours and the other times(P<.05). $BelleGlass^{(R)}$ showed significant differences in width and weight between 24 hours and the other times. The two materials showed different changing patterns of the dimensions but there were no statistically significant differences between them. Conclusion: The dimensions and weight of the Ceromer restorations were changed by water absorption. The clinical crown shaped specimen showed more complicated dimensional changes than the simplified specimens.

• Restorative Dentistry and Endodontics
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• v.32 no.3
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• pp.191-197
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• 2007

Mineral trioxide aggregate (MTA) would influence healing of periapical tissues by modulating the production of growth factors and cytokines from PDL fibroblasts, however, the studies are insufficient. Therefore, the purpose of this study was to monitor the expression of transforming growth factor-beta1 $(TGF-\beta1)$, fibroblast growth factor-2 (FGF-2), and interleukin-6 (IL-6) from PDL fibroblasts in the presence of MTA. The human PDL fibroblasts were seeded onto the set MTA or IRM at a level of $1\times10^5$ cells per unit well, and further incubated for 6, 12, 24, and 48 hours. The levels of $TGF-\beta1$, FGF-2 and IL-6 from the supernatant were measured by enzyme-linked immunosorbent assay (ELISA) The data were analyzed using one-way ANOVA. The level of $TGF-\beta1$ was down-reg ulated when the cells were grown in the presence of MTA except at 6 hours. The levels of FGF-2 release were significantly suppressed when PDL fibroblasts were grown in the presence of MTA or IRM at all time intervals (p < 0.05). The expressions of IL-6 from MTA treated co)Is were comparable to those of untreated control cells throughout the observation periods. We presume that this material inhibits the stimulatory function of growth factors on granulation tissue formation and in turn, it promotes the healing process modulated by other bone-remodeling cells.

• Restorative Dentistry and Endodontics
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• v.24 no.2
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• pp.330-336
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• 1999

In biological systems, the mineral that forms hard tissue is of an apatitic nature, and hydroxyapatite($Ca_5OH(PO_4)_3$: HA) is generally considered as the prototype for such a mineral. Thus, the precipitation of HA, having biological implications, has been the subject of several investigations. Crystal growth studies using HA seeds in supersaturated solutions have enhanced our understanding of the process and mechanism involved in seeded crystal growth. From these studies, it has become apparent that the precipitation rate of HA onto the seed crystals depends on the various conditions, especially on the additives. The relation between the supersaturated solution containing fluoride and the process of HA crystal growth enhances the understanding of mechanism of HA crystal growth. Until recently, the studies have been on the crystal growth of enamel minerals and synthetic HA seeds in the supersaturated solution containing 1~2 ppm fluoride. The purpose of the present investigation is to study the effect that fluoride of high concentration has on the crystal growth kinetics of HA. In order to produce the composition found in the secretory enamel fluid, experimental solutions of 1mM Ca, 3mM P, and 100mM Tris as background electrolyte were used. Then this experimental solutions were added to 0, 2, 4, 6, 8, 10 ppm fluoride. The effect of fluoride at high concentrations on the precipitation was examined in a bench-top crystal growth model adopting a miniaturized reaction column. Chemical analysis was employed for characterization of working solutions before and after the experimentation. Remarkable findings were : 1) the amount of crystal growth was gradually accelerated as the fluoride concentration increased until 6 ppm, but decreased in 8 and 10 ppm fluoride; 2) the amount of fluoride ion consumed in crystal formation was constant despite the increase in fluoride concentration.

• Restorative Dentistry and Endodontics
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• v.24 no.2
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• pp.416-425
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• 1999

The purpose of this study was to evaluate shear bond strength of glass ionomer cements and compomer according to dentin surface treatment method. The materials used in this study were dentin conditioner and cavity conditioner for dentin treatment: Ketacfil, Fuji II LC, and Dyract for restoration. In this study, 90 sound bovine teeth were selected and then the teeth were embeded in improved stone and were grounded with 400 to 600 grit silicon carbide paper to create a flat dentin surfaces. The teeth were divided into nine groups as follows ; Group 1A : Samples bonded to dentin surface with Ketacfil after no treatment Group 1B : Samples bonded to dentin surface with Ketacfil after applicating dentin conditioner Group 1C : Samples bonded to dentin surface with Ketacfil after applicating cavity conditioner Group 2A : Samples bonded to dentin surface with Fuji II LC after no treatment Group 2B : Samples bonded to dentin surface with Fuji II LC after applicating dentin conditioner Group 2C : Samples bonded to dentin surface with Fuji II LC after applicating cavity conditioner Group 3A : Samples bonded to dentin surface with Dyract after no treatment Group 3B : Samples bonded to dentin surface with Dyract after applicating dentin conditioner Group 3C : Samples bonded to dentin surface with Dyract after applicating cavity conditioner Treated dentin surfaces were observed under SEM. After filling of each materials, shear bond strenth was evaluated and then debonded surfaces were observed under SEM. The following results were obtained; 1. The shear bond strengths obtained were decreased as Fuji II LC, Dyract, Ketacfil in that order and there was statistically significant difference(p<0.05). 2. About Group 1. the shear bond strengths were decreased as 1C, 1B and 1A in that order. But there was no significant difference between group 1B and 1C (p<0.05). 3. About Group 2, the shear bond strengths were decreased as group 2B, 2A and 2C in that order. And there was significant difference between group 2B and 2C (p<0.05). 4. About Group 3, the shear bond strengths were decreased as group 3A, 3C and 3B in that order. And there was signicant difference between group 3A and 3B (p<0.05). 5. As a result of observation under SEM, the fracture patterns of Fuji II LC and Dyract were adhesive failures, but those of Ketacfil were cohesive failure of material and mixture of cohesive and adhesive failure.

• Restorative Dentistry and Endodontics
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• v.20 no.2
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• pp.463-486
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• 1995

The effect of moistening and air-drying of acid-conditioned dentin before priming on the formation of resin-dentin hybrid zone was investigated, Freshly extracted human molars were used and divided at random into 5 groups, Groups 1 - 3 consisted of specimens conditioned with 10 % phosphoric acid for 20 seconds; Group 1 served as a control in which the conditioned dentin was simply blot-dried with a damp facial tissue; Group 2 was air dried for 30 seconds ; Group 3 was air dried for 30 seconds and immediately remoistened for 10 seconds with air-water syringe. and then the specimen was blot-dried with a damp facial tissue. Groups 4-5 were not acid conditioned ; In group 4, the smear layer on the dentin was blot dried before primer placement; Group 5 was air dried only for 30 seconds, The acetone-based primer and bonding agent of All Bond 2 (Bisco. Inc., USA) and composite resin (Z-100, 3M Dental products, USA) were applied for acid conditioned dentin and non-conditioned dentin. The morphologic ultrastructure of resin-dentin hybrid zone was examined by the use of SEM and TEM. and the existence of inorganic material and analysis of Ca/P weight-percent ratio in the resin-dentin hybrid zone were revealed by the EDAX, The results were as follows : 1. In the moistened specimens from acid-conditioned groups, the resin penetrated about 3-$4{\mu}m$ into dentin and the denatured collagen smear layer was not present at the surface. The resin tag was formed to a thickeness of 3-$4{\mu}m$ at the upper part of dentinal tubule and compactively connected to each other by means of many lateral branching. 2. In the air-dried specimens from acid-conditioned groups, the resin penetrated about 2.0-$2.5\;{\mu}m$ into dentin and an upper thin black layer to a thickness of 30-35nm was identified between adhesive resin and demineralized collagen layer. The resin tag to have a diameter of $2.5{\mu}m$ was formed at the upper part of dentinal tubule. However the funnel shape of the tag was not notable compared to the moistened specimens. 3. In the remoistened specimens from acid conditioned groups, the resin penetrated about 2.0-$2.5{\mu}m$ into dentin and an upper black layer was not present. The resin tag at the upper part of dentinal tubule was formed less than $2{\mu}m$ and was weakly connected to each other by means of few lateral branching. 4. In the non-conditioned groups, the smear layer was formed to a thickness of $0.5{\mu}m$ at dentin surface. However, the resin-dentin hybrid zone was not identified by TEM. The evidence of resin penetration into intertubular and intratubular dentin did not show. 5. All the acid-conditioned groups showed that the detected calcium and phosphorus weight percent ratios at the $2{\mu}m$ upper portion from the resin-dentin interface into the resin were much higher than that at the $2{\mu}m$ lower portion from the resin-dentin interface to dentin. (P<0.01).