• Restorative Dentistry and Endodontics
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• v.36 no.6
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• pp.515-520
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• 2011

One of the most challenging task in closing anterior diastema is avoiding "black triangle" between the teeth. This paper reports a case that the closure of diastema in anterior teeth could be successfully accomplished using direct adhesive restorations and gingival recontouring. The traditional technique using Mylar strip was modified to increase the emergence profile with natural contours at the gingival-tooth interface. Mylar strip was extended out of the sulcus by approximately 1 mm high from the gingival margin, and a small cotton pellet was used to provide the emergence contour. This modified approach is acceptable for the clinical situation.

• Restorative Dentistry and Endodontics
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• v.28 no.5
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• pp.369-377
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• 2003

The aim of this study was to evaluate the effect of two polishing methods and chemical conditioning on the surface of hybrid composites. Ninety cylindrical specimens (diameter：8mm, depth：2mm) were made with three hybrid composites-Filtek Z250, Tetric Ceram. DenFil. Specimens for each composite were randomly divided into three treatment subgroups $^{\circled1}$ Mylar strip (no treatment). $^{\circled2}$ Sof-Lex XT system, $^{\circled3}$ PoGo system. Average surface roughness(Ra) was taken using a surface profilometer at the time of setting and after immersion into 0.02N lactic acid for 1 week and 1 month. Representative specimens were examined by scanning electron microscopy. The data were analyzed using ANOVA and Scheffe's tests at 0.05% significance level. The results were as follows：1. Mylar strip resulted in smoother surface than PoGo and Sof-Lex system (p<0.001). Sof-Lex system gave the worst results. 2. Tetric Ceram was smoother than DenFil and Z250 when cured under only mylar strip. However, it was significantly rougher than other materials when polished with PoGo system. 3. All materials showed rough surface after storage in 0.02N lactic acid, except groups polished with a PoGo system. The PoGo system gave a superior polish than Sof-Lex system for the three composites. However. the correlation to clinical practice may be limited, since there are several processes. such as abrasive, fatigue, and corrosive mechanisms. Thus. further studies are needed for polishing technique under in vivo conditions.

• Restorative Dentistry and Endodontics
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• v.36 no.6
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• pp.483-489
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• 2011

Objectives: The purpose of this study was to examine the effect of glycerin topical application on the surface hardness of composite after curing. Materials and Methods: A composite (Z-250, 3M ESPE) was packed into a disc-shaped brass mold and light cured according to one of the following protocols. Group 1 (control) was exposed to air and light cured for 40 sec, group 2 was covered with a Mylar strip and light cured for 40 sec, group 3 was surface coated with glycerin and light cured for 40 sec, and group 4 was exposed to air and light cured for 20 sec and then surface coated with glycerin and cured for additional 20 sec. Twenty specimens were prepared for each group. The surface hardnesses of specimens were measured with or without polishing. Five days later, the surface hardness of each specimen was measured again. Data were analyzed by three-way ANOVA and Tukey's post hoc tests. Results: The surface hardnesses of the unpolished specimens immediately after curing decreased in the following order: group 2 > 3 > 4 > 1. For the polished specimens, there was no significant difference among the groups. Within the same group, the hardness measured after five days was increased compared to that immediately after curing, and the polished specimens showed greater hardness than did the unpolished specimens. Conclusions: The most effective way to increase the surface hardness of composite is polishing after curing. The uses of a Mylar strip or glycerin topical application before curing is recommended.

• Restorative Dentistry and Endodontics
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• v.33 no.1
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• pp.1-8
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• 2008

The purpose of this study was to evaluate the effect of a new resin monomer, filler size and polishing technique on the surface roughness of composite resin restorations using confocal laser scanning microscopy. By adding new methoxylated Bis-GMA (Bis-M-GMA, 2,2-bis[4-(2-methoxy-3-methacryloyloxy propoxy) phenyl] propane) having low viscosity, the content of TEGDMA might be decreased. Three experimental composite resins were made: EX1 (Bis-M-GMA/TEGDMA = 95/5 wt%, 40 nm nanofillers); EX2 (Bis-M-GMA/TEGDMA = 95/5 wt%, 20 nm nanofillers); EX3 (Bis-GMA/TEGDMA = 70/30 wt%, 40 nm nanofillers). Filtek Z250 was used as a reference. Nine specimens (6 mm in diameter and 2 mm in thickness) for each experimental composite resin and Filtek Z250 were fabricated in a teflon mold and assigned to three groups. In Mylar strip group, specimens were left undisturbed. In Sof-lex group, specimens were ground with #1000 SiC paper and polished with Sof-lex discs. In DiaPolisher group, specimens were ground with #1000 SiC paper and polished with DiaPolisher polishing points. The Ra (Average roughness), Rq (Root mean square roughness), Rv (Valley roughness), Rp (Peak roughness), Rc (2D roughness) and Sc (3D roughness) values were determined using confocal laser scanning microscopy. The data were statistically analyzed by Two-way ANOVA and Tukey multiple comparisons test (p = 0.05). The type of composite resin and polishing technique significantly affected the surface roughness of the composite resin restorations (p < 0.001). EX3 showed the smoothest surface compared to the other composite resins (p < 0.05). Mylar strip resulted in smoother surface than other polishing techniques (p < 0.05). Bis-M-GMA. a new resin monomer having low viscosity, might reduce the amount of diluent, but showed adverse effect on the surface roughness of composite resin restorations.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.2
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• pp.105-115
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• 2008

Statement of problem: Proper finishing and polishing enhance both the esthetics and the longevity of restored teeth. Blade finishing technique would be suited for smoothing and finishing. Evaluation of this technique are necessary. Purpose: The purpose of this study was to evaluate the blade finishing and polishing procedures on the surface profile and roughness of ormocer-based composite resin and nanohybrid composite resin. Material and methods: The material included a ormocer-based composite resin ($Admira^{(R)}$ & $Admira^{(R)}$ Flow); a nanohybrid composite resin ($Grandio^{(R)}$ & $Grandio^{(R)}$ Flow). One hundred forty specimens of each group were prepared using a mylar strip and randomly divied into blade finishing and rubber polishing groups (n=10). The average surface roughness (Ra) in micrometers was measured and the surface profile was examined by scanning electron microscopy (SEM) (Magnification ${\times}$ 200). The data were analyzed by Mann-Whitney Test at 0.05 significance level. Conclusion: The results of this study indicated that the mylar strip produced the smoothest surface on all materials and among the finishing-polishing methods was not significanct difference (P>0.05). Ormocer-based flowable composite resin performedthe lowest variability in initial surface roughness among the tested materials.

• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.4
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• pp.634-643
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• 2005

The aim of this study is to evaluate the effects of blue light emitting diode (LED) Light Curing Units (FreeLight 2, L.E.Demetron I, Ultra-Lume 5) on the microhardness of three resin composites (Z250, Point 4, Dyract AP) and to determine their optimal curing time. Samples were made using acrylic molds $(2.0mm{\times}3mm)$ of each composite. All samples were prepared over a Mylar strip placed on a flat glass surface. After composite placement on the molds, the top surface was covered with another Mylar strip and a glass slab was gently pressed over it. The times of irradiation were as follows: Elipar TriLight, 40 s; Elipar FreeLight 2. L.E.Demetron I, and Ultra-Lume 5, 10s, 20s, 40s, respectively. Mean hardness values were calculated at the top and bottom for each group. ANOVA and Sheffe's test were used to evaluate the statistical significance of the results. Results showed that FreeLight 2, Ultra-Lume 5, and L.E.Demetron I were able to polymerize point 4 in 20 seconds to a degree equal to that of the halogen control at 40 seconds. FreeLight 2 and L.E.Demetron I were able to polymerize Z250 in 10 seconds to a degree equal to that of the halogen control at 20 seconds. FreeLight 2 and L.E.Demetron I were able to polymerize Dyract AP in 10 seconds to a degree equal to that of the halogen control at 40 seconds. The commercially available LED curing lights used in this study showed an adequate microhardness with less than half of the exposure time of a halogen curing unit.

• Restorative Dentistry and Endodontics
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• v.33 no.4
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• pp.405-412
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• 2008

This study was aimed to investigate whether an oxygen inhibition layer (OIL) is essential for the interfacial bonding between resin composite layers or not. A composite (Z-250, 3M ESPE) was filled in two layers using two aluminum plate molds with a hole of 3.7 mm diameter. The surface of first layer of cured composite was prepared by one of five methods as followings, thereafter second layer of composite was filled and cured: Group 1 - OIL is allowed to remain on the surface of cured composite; Group 2 - OIL was removed by rubbing with acetone-soaked cotton; Group 3 - formation of the OIL was inhibited using a Mylar strip; Group 4 - OIL was covered with glycerin and light-cured; Group 5 (control) - composite was bulk-filled in a layer. The interfacial shear bond strength between two layers was tested and the fracture modes were observed. To investigate the propagation of polymerization reaction from active area having a photo-initiator to inactive area without the initiator, a flowable composite (Aelite Flow) or an adhesive resin (Adhesive of ScotchBond Multipurpose) was placed over an experimental composite (Exp_Com) which does not include a photoinitiator and light-cured. After sectioning the specimen, the cured thickness of the Exp_Com was measured. The bond strength of group 2, 3 and 4 did not show statistically significant difference with group 1. Groups 3 and 4 were not statistically significant different with control group 5. The cured thicknesses of Exp_Com under the flowable resin and adhesive resin were 20.95 (0.90) urn and 42.13 (2.09), respectively.

• Restorative Dentistry and Endodontics
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• v.8 no.1
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• pp.97-106
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• 1982

The purpose of this study was to evaluate the effect of different polishing procedures on the surfaces of composite resins. Two-paste type comosite restorative resin (Hipol) was selected for this study. 70 cavities prepared on the plaster-stone dies, 6mm in diameter and 2mm in depth, was filled with composite resin according to the manufacturer's specifications and by polymerizing against mylar strips. The polymerized composite resin specimens were polished (surface finished) by using 6 polishing devices; white stones, diamond finishing points, 12-fluted carbide finishing burs, green stones, sand paper disks, and Quasite rubber disk after polished with sand paper disks and green stones. A profilometer (Bendix type) was used to record in microinches the surface roughness of each surface finished composite resin specimens. The results were as follows. 1. The best finished surface that can be obtained is a surface formed by the mylar matrix strip 2. The white stones produced the smoothest surface in the experimental group. 3. The green stones produced the roughest surface in the experimental group. 4. It was proved that the gradual use of finishing instruments from a rough one to fine ones reduced the surface roughness.

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.3
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• pp.453-458
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• 2003

Usually Mylar strip and wedge or celluloid strip crown were used in conventional method of restoring proximal carious lesions of primary anterior teeth. But, these methods have some difficulties to place the matrix and wedge due to short crown lenth and interdental spacing of primary teeth. And it is difficult to form proper cavosurface margin due to the rigidity of matrix and inconvenience to support matrix by practitioner's hand in narrow oral cavity of child. This article describes an alternative technique for restoring carious lesions of primary anterior teeth using available straw. This method is very convenient and reduce chair time and it also allows good marginal adaptation.

• Restorative Dentistry and Endodontics
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• v.21 no.1
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• pp.360-365
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• 1996

The purpose of this study was to evaluate the changes in the degree of conversion on a composite resin surface following heat treatment and mylar strip finishing. The effects of the time interval between the light-curing and heat-curing process were also evaluated. The composite resin surface which had been covered with a coverglass showed a lower conversion rate than the surface from which a layer of $500{\mu}m$ was ground away. The composite resin surface was definitely affected by oxygen during the heat curing process when it had not been insulated. When the composite resins were heat cured after 3 days of storage following the light curing process, the increased in the degree of conversion through heatcuring was limited.