• Journal of the korean academy of Pediatric Dentistry
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• v.24 no.2
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• pp.436-448
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• 1997

Topical fluoride application for children is a widely performed procedure in the field of Pediatric Dentistry for its dental caries prevention effects. However, it is recently recognized as having some unwanted effects on several esthetic restorative materials as it roughens the surfaces of the restorative materials. In order to evaluate the surface changes in esthetic restorative materials, the author immersed composite resin, glass ionomer cement, and resin-modified glass ionomer cement specimens in various topical fluoride agents and measured the weight loss and also, examined the specimens under the scanning electron microscope. The followings are the results : 1. All the specimens immersed in APF gel for 4 minutes showed statistically significant weight loss. (paired t-test, P<0.05). 2. There was no statistically significant weight loss for the resin-modified glass ionomer cement and composite resin groups immersed in sodium fluoride solution (paired t-test, P>0.05). 3. When the glass ionomer cement group was immersed in APF gel for 1 and 4 minutes, there was a statistically significant weight loss compare to other esthetic restorative materials (ANOVA, P<0.05). 4. In the resin-modified glass ionomer cement group and the composite resin group, weight loss in the APF gel 4 minutes immersion group was greater than the 1 minute immersion group, and it was statistically significant (ANOVA, P<0.05). 5. When the specimens were examined under scanning electron microscope, the surface changes were greatest in the order of glass ionomer cement, resin-modified glass ionomer cement, composite resin and also in the order of APF gel 4 minute immersion group, 1 minute immersion group, sodium fluoride immersion group, and control group.

• Restorative Dentistry and Endodontics
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• v.23 no.1
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• pp.468-476
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• 1998

The purpose of this study was to observe the morphologic change of dentinal surface, adhesion in interface between dentin and bonding agents, and penetration pattern of resin tags into dentinal tubles according to bonding procedure of ONE-STEP universal adhesive system. Ten extracted human molars were mounted in dental stone and sectioned to expose mid-coronal occlusal dentin and again sectioned tooth crown apically. Specimens were randomly assigned to three groups for dentin conditioning with 32% phoshoric acid, two coats of bonding agents after dentin conditioning, and bond of composite resin. The surfaces of dentin were treated with etch ant and applied bonding agent, and bonded composite resin according to the directions of manufacturer. Specimens which were boned composite were sectioned longitudinally for observing interfaces between resin and dentin. Two of specimens which were sectioned longitudinally were immersed in 6 N HCL for 30 seconds and 1% NaOCL for 12 hours to partially demineralize and deproteinize the dentin substrate. Each specimen was mounted on a brass stub, sputter-coated with gold and observed under SEM. The result were as follows : 1. On the dentinal surface which was conditioned with 32% phosphoric acid. the smear layer was completely removed. orifices of dentinal tubules were opened 3-$5{\mu}m$ wide. and dentinal surface was irregular. 2. On the dentinal surface which was applied ONE-STEP. bonding agent. resin particles were observed on the orifices of dentinal tubules and intertubular dentin. 3. There were close adaptation between dentin and resin and were the pattern which composite invaded into dentin. 4. 1-$3{\mu}m$-wide hybrid layer was visible in the interface between dentin and resin. 5. Long and funnel shaped resin tags were observed in demineralized specimens. and the surfaces of tags were rough.

• Restorative Dentistry and Endodontics
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• v.39 no.4
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• pp.310-318
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• 2014

Objectives: This study examined the influence of the resin thickness on the polymerization of silorane- and methacrylate-based composites. Materials and Methods: One silorane-based (Filtek P90, 3M ESPE) and two methacrylate-based (Filtek Z250 and Z350, 3M ESPE) composite resins were used. The number of photons were detected using a photodiode detector at the different thicknesses (thickness, 1, 2 and 3 mm) specimens. The microhardness of the top and bottom surfaces was measured (n = 15) using a Vickers hardness with 200 gf load and 15 sec dwell time conditions. The degree of conversion (DC) of the specimens was determined using Fourier transform infrared spectroscopy (FTIR). Scratched powder of each top and bottom surface of the specimen dissolved in ethanol for transmission FTIR spectroscopy. The refractive index was measured using a Abbe-type refractometer. To measure the polymerization shrinkage, a linometer was used. The results were analyzed using two-way ANOVA and Tukey's test at p < 0.05 level. Results: The silorane-based resin composite showed the lowest filler content and light attenuation among the specimens. P90 showed the highest values in the DC and the lowest microhardness at all depth. In the polymerization shrinkage, P90 showed a significantly lower shrinkage than the rest two resin products (p < 0.05). P90 showed a significantly lower refractive index than the remaining two resin products (p < 0.05). Conclusions: DC, microhardness, polymerization rate and refractive index linearly decreased as specimen thickness linearly increased. P90 showed much less polymerization shrinkage compared to other specimens. P90, even though achieved the highest DC, showed the lowest microhardness and refractive index.

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.2
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• pp.255-263
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• 2007

Composite resin restorations are widely used to restore decayed teeth or preventive restoration in children. Children often receive topical fluoride treatments on a semiannual basis. However there is concern that topical acidulated phosphate fluorides (APF) may cause deterioration of composite resins. The aim of this study was to evaluate the surface changes in composite resins due to topical fluoride application. Composite resins(Solitaire $2^{(R)}$, Metafil $CX^{(R)}$, Composan $LCM^{(R)}$, $Charmseal^{(R)}$) in topical fluoride agents were immersed and their surface roughness, weight loss and SEM findings were evaluated. The results were as follows: 1. The 4 minutes-immersion group showed more roughened surface than 1 minute-immersion group and the control group showed the smoothest surface among all the materials, and there was statistically significant difference between the groups except the Composan $LCM^{(R)}$ (P<0.05). 2. There was no significant difference between the 1 minute-immersion group and 4 minutes-immersion group in weight loss (P>0.05) 3. The experimental group treated with topical fluoride gel showed generally more roughened surface than control group in the SEM findings.

• Journal of Dental Rehabilitation and Applied Science
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• v.30 no.2
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• pp.145-151
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• 2014

Purpose: The purpose of this study was to investigate the microleakage in class II cavity resin restorations used with resin-modified glass ionomer (RMGI) lining material depending on two different applying methods; classical delivery method using a dental explorer and a specially designed rotating bur. Materials and Methods: A total thirty-six extracted teeth were prepared with a class II proximal box, and randomly divided into three groups: 1) control group with no lining added and the proximal box restored (Group I), 2) the second group used RMGI as a lining material which was spread with an explorer (Group II), 3) the third group used a specially designed rotating bur to thin out RMGI (Group III). All teeth were restored with the same manner using incrementally placed resin composite. All 36 teeth were prepared and sectioned for the dye penetration test, and observed with a stereomicroscope for scoring the dye penetration. Results: When RMGI liners were used, both groups using an explorer and the special bur with the liner had significantly less microleakage than the control group with no liner (P < 0.05). The 50% of the group with RMGI liner using the bur showed no microleakage under a dye penetration test whereas all the teeth in control group showed microleakage of different degrees. However, there was no statistically significant difference between Group II and Group III. Conclusion: RMGI is an effective lining material to decrease microleakage in class II composite resin restorations regardless of applying methods.

• The Journal of the Korean dental association
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• v.15 no.11
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• pp.757-761
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• 1977

The purpose of this study was to evaluate the marginal sealing ability of Hipol composite resin. Using freshly extracted human teeth and 2% acquous methylene blue, the marginal leakage of dye in restorative materials such as Hi-pol, Adaptic, Nuvasystem, Epolite and Amalgam was investigated at 37℃ and under temperature cycling between 4℃ and 60℃. The results were as follows; 1. All the filling materials revealed the penetration of dye between cavity walls and restorations. 2. Hi-pol and Adaptic showed more marginal leakage than other materials and the degree of dye penetration in Hi-pol was similar to that of Adaptic. 3. Nuva system showed the least marginal leakage at 37℃ and under temperature cycling between 4℃ and 60℃. 4. Under temperature cycling, all materials showed a slight increase in marginal leakage except Epolite, which showed the greastest change in leakage.

• 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.

• Applied Chemistry for Engineering
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• v.16 no.5
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• pp.672-676
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• 2005

To improve the application of polymeric dental restorative composite (PDRC) for the posterior and anterior restoration, silica bridged with siloxane unit was firstly prepared by heat-treating a silica filler at various temperatures. Degree of conversion (DC), depth of cure, and dynamic volumetric polymerization shrinkage values of PDRC filled with silica bridged with siloxane unit were investigated to study the effect of heat-treated silica on the polymerization behavior of PDRC. From the experimental result, it was found that depth of cure was decreased with an increase of heat treatment temperature. on the other hand, both DC and polymerization shrinkage values were uniformly enhanced with increasing the heat treatment temperature. This phenomenon can be explained from the study that showed decrease of average particle size of silica resulted in the increase of relative amount of resin matrix in PDRC.

• The Journal of Korean Academy of Prosthodontics
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• v.52 no.3
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• pp.202-210
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• 2014

Purpose: The aim of this study was to evaluate the stress concentration and distribution whether restoring the cavity or not while restoring with metal ceramic crown on tooth with abfraction lesion using finite element analysis. Materials and methods: Maxillary first premolar was selected and made a total of 10 finite element model. Model 1 was natural tooth; Model 2 was tooth with metal ceramic crown restoration which margin was positioned above 2 mm from CEJ; Model 3 was tooth with metal ceramic crown restoration which margin was positioned on CEJ; Model 4 was natural tooth which has abfraction lesion; Model 5 and 6 had abfraction lesion and the other condition was same as model 2 and 3, respectively; Model 7 was natural tooth which had abfraction lesion restored with composite resin; Model 8 and 9 was tooth with metal ceramic crown after restoring on abfraction lesion with composite resin; Model 10 was restored tooth on abfraction lesion with composite resin and metal ceramic crown restoration which margin is positioned on lower border of abfraction lesion. Load A and Load B was also designed. Von Mises value was evaluated on each point. Results: Under load A or load B, on tooth with abfraction lesion, stress was concentrated on the apex of lesion. Under load A or load B, on tooth that abfraction lesion was restored with composite resin, the stress value was reduced on the apex. Conclusion: In case of abfraction lesion was restored with composite resin, the stress was concentrated on the apical border of restored cavity regardless of marginal position. It was favorable to place crown margin on the enamel for restoring with metal ceramic crown.

• The Journal of Korean Academy of Prosthodontics
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• v.40 no.2
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• pp.201-212
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• 2002

This study investigated the shear bond strengths between abrasion-resistant denture teeth and composite resins according to surface treatments. Denture teeth for this study were Trubyte IPN teeth(Dentsply Inc., USA) with interpenetrating polymer network and Endura Posterio (Shofu Inc. Japan) of composite resin teeth, and restorative composite resins were Clearfil FII (Kuraray, Japan) of the self-cured composite resin and Z100(3M Dental Product, USA) of the light-cured composite resin. Five different surface treatments were evaluated: (1) $50{\mu}m\;A1_2O_3$ sandblasting: (2) #100 carbide paper; (3) chloroform; (4) retentive holes; and (5) no treatment. After surface treatments, denture teeth were examined by scanning electron microscopy(SEM), and the maximum shear bond strengths between abrasion-resistant denture teeth and composite resins were measured using Instron. The results were as follows; 1. IPN teeth treated with sandblasting had the highest shear bond strength, and Endura treated with sandblasting and carbide paper had significantly greater shear bond strength than with any other surface treatment. 2. Regardless or composite resins, the shear bond strength on Endura was greater than on IPN teeth. 3. Regardless of denture teeth, the shear bond strength of Clearfil FII was greater han of Z100. 4. In appearance of SEM, IPN teeth treated with sandblasting showed generalized roughness on the all of surface, however, carbide paper treatment resulted in partly rough. Endura treated with sandblasting and carbide paper showed similar surface characteristics. Wetting denture teeth surface with chloroform removed the debris and created a particle-free and smooth surface.