• Korean Journal of Microbiology
• /
• v.52 no.2
• /
• pp.140-147
• /
• 2016

A process for manufacturing virally-safe porcine bone hydroxyapatite (HA) has been developed to serve as advanced xenograft material for dental applications. Porcine bone pieces were defatted with successive treatments of 30% hydrogen peroxide and 80% ethyl alcohol. The defatted porcine bone pieces were heat-treated in an oxygen atmosphere box furnace at $1,300^{\circ}C$ to remove collagen and organic compounds. The bone pieces were ground with a grinder and then the bone powder was sterilized by gamma irradiation. Morphological characteristics such as SEM (Scanning Electron Microscopy) and TEM (Transmission Electron Microscopy) images of the resulting porcine bone HA (THE Graft$^{(R)}$) were similar to those of a commercial bovine bone HA (Bio-Oss$^{(R)}$). In order to evaluate the efficacy of $1,300^{\circ}C$ heat treatment and gamma irradiation at a dose of 25 kGy for the inactivation of porcine viruses during the manufacture of porcine bone HA, a variety of experimental porcine viruses including transmissible gastroenteritis virus (TGEV), pseudorabies virus (PRV), porcine rotavirus (PRoV), and porcine parvovirus (PPV) were chosen. TGEV, PRV, PRoV, and PPV were completely inactivated to undetectable levels during the $1,300^{\circ}C$ heat treatment. The mean log reduction factors achieved were $${\geq_-}4.65$$ for TGEV, $${\geq_-}5.81$$ for PRV, $${\geq_-}6.28$$ for PRoV, and $${\geq_-}5.21$$ for PPV. Gamma irradiation was also very effective at inactivating the viruses. TGEV, PRV, PRoV, and PPV were completely inactivated to undetectable levels during the gamma irradiation. The mean log reduction factors achieved were $${\geq_-}4.65$$ for TGEV, $${\geq_-}5.87$$ for PRV, $${\geq_-}6.05$$ for PRoV, and $${\geq_-}4.89$$ for PPV. The cumulative log reduction factors achieved using the two different virus inactivation processes were $${\geq_-}9.30$$ for TGEV, $${\geq_-}11.68$$ for PRV, $${\geq_-}12.33$$ for PRoV, and $${\geq_-}10.10$$ for PPV. These results indicate that the manufacturing process for porcine bone HA from porcine-bone material has sufficient virus-reducing capacity to achieve a high margin of virus safety.

• Restorative Dentistry and Endodontics
• /
• v.34 no.2
• /
• pp.154-161
• /
• 2009

This clinical study evaluated the whitening effect and safety of polymer based-pen type BlancTis Forte (NIBEC) containing 8.3% carbamide peroxide. Twenty volunteers used the BlancTis Forte whitening agent for 2 hours twice a day for 4 weeks. As a control. Whitening Effect Pen (LG) containing 3% hydrogen peroxide was used by 20 volunteers using the same protocol. The change in shade (${\Delta}E^*$, color difference) was measured using $Shadepilot^{TM}$ (DeguDent) before, during, and after bleaching (2 weeks, 4 weeks, and post-bleaching 4 weeks). A clinical examination for any side effects (tooth hypersensitivity or soft tissue complications) was also performed at each check-up. The following results were obtained. 1. Both the experimental and control groups displayed a noticeable change in shade (${\Delta}E$) of over 2. No significant differences were found between the two groups (p > 0.05), implying that the two agents have a similar whitening effect.2. The whitening effect was mainly due to changes in a and b values rather than in L value (brightness). The experimental group showed a significantly higher change in b value, thus yellow shade, than the control (p < 0.05). 3. None of the participants complained of tooth hypersensitivity or soft tissue complications, confirming the safety of both whitening agents.

• Restorative Dentistry and Endodontics
• /
• v.36 no.4
• /
• pp.306-312
• /
• 2011

Objectives: This clinical study evaluated the effect of light activation on the whitening efficacy and safety of in-office bleaching system containing 15% hydrogen peroxide gel. Materials and Methods: Thirty-three volunteers were randomly treated with (n = 17, experimental group) or without light activation (n = 16, control group), using Zoom2 white gel (15% $H_2O_2$, Discus Dental) for a total treatment time of 45 min. Visual and instrumental color measurements were obtained using Vitapan Classical shade guide and Shadepilot (DeguDent) at screening test, after bleaching, and 1 month and 3 month after bleaching. Data were analyzed using t-test, repeated measure ANOVA, and chi-squared test. Results: Zoom2 white gel produced significant shade changes in both experimental and control group when pre-treatment shade was compared with that after bleaching. However, shade difference between two groups was not statistically significant (p > 0.05). Tooth shade relapse was not detected at 3 months after bleaching. The incidence of transient tooth sensitivity was 39.4%, with being no differences between two groups. Conclusions: The application of light activation with Zoom2 white gel system neither achieved additional whitening effects nor showed more detrimental influences.

• Restorative Dentistry and Endodontics
• /
• v.32 no.3
• /
• pp.180-190
• /
• 2007

The purpose of this study was to evaluate the abrasion resistance of surface penetrating sealant which was applied on a composite resin restoration and to provide proper time to reapply sealant on composite resin surface. Two hundred rectangular specimens, sized $8\times3\times2mm$, were made of Micronew (Bisco, Inc., Schaumburg, IL, U.S.A) and divided into two groups; F group (n = 10) was finished with coarse and medium grit of Sof-Lex discs and BisCoverwas applied B group (n = 190) after finishing with discs. B group was again subdivided into nineteen subgroups From B-1 group to B-18 group were subjected to toothbrush abrasion test using a distilled water-dentifrice slurry and toothbrush heads B-IM group was not subjected to toothbrush abrasion test. Average surface roughness (Ra) of each group was calculated using a surface roughness tester (Surfcorder MSE-1700: Kosaka Laboratory Ltd., Tokyo, Japan) . A representative specimen of each group was examined by FE-SEM (S-4700: Hitachi High Technologies Co., Tokyo, Japan). The data were analysed using cluster analysis, paired t-test, and repeated measure ANOVA. The results of this study were as follows; 1. Ra off group was $0.898{\pm}0.145{\mu}m$ and B-IM group was $0.289{\pm}0.142{\mu}m$. Ra became higher from B-1 group $(0.299{\pm}0.48{\mu}m$ to B-18 group $(0.642{\pm}0.313{\mu}m$. 2. Final cluster center of Ra was $0.361{\mu}m$ in cluster 1 $(B-IM\simB-7)$, $0.511{\mu}m$ in cluster 2 $(B-8\simB-14)$ and $0.624{\mu}m$ in cluster 3 ($(B-15\simB-18)$. There were significant difference among Ra of three clusters. 3 Ra of B-IM group was decreased 210.72% than Ra of F group. Ra of B-8 group and B-15 group was increased 35.49% and 51.35% respectively than Ra of B-IM group. 4. On FE-SEM, B-IM group showed the smoothest resin surface. B-8 group and B-15 group showed vertically shallow scratches , and wide and irregular vertical scratches on composite resin surface respectively. Within a limitation of this study, finished resin surface will be again smooth and glazy if BisCover would be reapplied within 8 to 14 months after applying to resin surface.

• Restorative Dentistry and Endodontics
• /
• v.33 no.4
• /
• pp.389-396
• /
• 2008

The purpose of this study was to evaluate the color stability of resin cements with accelerated test. Four dual curing resin cements: Panavia-F (KURARAY). Duolink (BISCO), Variolink-II (Ivoclar Vivadent), and RelyX Unicem (3M ESPE) and 1 self curing resin cement: Resiment CE (j. l. Blosser) were used in this study. In control group, Gradia Anterior (GC) composite resin and Tescera Dentin (Bisco) indirect composite were used. Ten disk shape specimens were made from each resin cement. The specimens were subjected to an accelerated aging process in a refrigerated bath circulator at 60$^{\circ}C$ for 15 and 30 days. Spectrophotometric analyses were made before and after 15 days and 30 days of accelerated aging time. The color characteristics ($L^*,\;a^*,\;b^*$) and the color difference (${\Delta}E^*$) of the specimens before and after immersion were measured and computed. Regardless of type of the resin cements, $L^*$ value was decreased and $a^*$ value was increased, but there were no significant difference. But $b^*$ value was increased significantly (p < 0.05). Tescera inlay showed least color change (p < 0.05), but Gradia showed notable color change after 15 days. After 30 days on accelerated aging, ${\Delta}E^*$ value was increased (Panavia-F < Variolink-II < Resiment CE < Duolink < Unicem) (p < 0.05). but there were no significant difference among Panavia-F, Variolink-II, and Resiment CE groups. After 30 days of accelerated aging, ${\Delta}E^*$ value of all resin cements were greater than 3.0 and could be perceived by the human eye.

• Restorative Dentistry and Endodontics
• /
• v.33 no.4
• /
• pp.405-412
• /
• 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
• /
• v.31 no.4
• /
• pp.263-268
• /
• 2006

Recently, self-etching adhesive system has been introduced to simplify the clinical bonding proce- dures. It is less acidic compared to the phosphoric acid, thus there is doubt whether this system has enough bond strength to enamel. The purpose of this study was to investigate the influence of additional etching on the adhesion of resin composite to enamel. Ninety extracted bovine permanent anterior teeth were used. The labial surfaces of the crown were ground with 600-grit abrasive paper under wet condition. The teeth were randomly divided into six groups of 15 teeth each. Clearfil SE $Bond^{\circledR},\;Adper^{TM}$ Prompt L-Pop and Tyrian $SPE^{TM}$ were used as self-etching primers. Each self-etching primers were applied in both enamel specimens with and without additional etching. For additional etching groups, enamel surface was pretreated with 32% phosphoric acid (UNI-ETCH, Bisco, Inc., Schaumburg, IL. USA). Hybrid resin composite Clearfil AP-X, (Kuraray Co., Ltd., Osaka, Japan) was packed into the mold and light-cured for 40 seconds. Twenty-four hours after storage, the specimens were tested in shear bond strength. The data for each group were subjected to independent t - test at p < 0.01 to make comparisons among the groups. In Clearfil SE $Bond^{\circledR}$, shear bond strength of additional etching group was higher than no additional etching group (p < 0.01). In $Adper^{TM}$ Prompt L-Pop and Tyrian SPE, there were no significant difference between additional etching and non-etching groups (p > 0.01). In conclusion, self-etching adhesive system with weak acid seems to have higher bond strength to enamel with additional etching, while self-etching adhesive system with strong acid seems not.

• Restorative Dentistry and Endodontics
• /
• v.34 no.2
• /
• pp.95-102
• /
• 2009

The aim of this study was to evaluate the influence of light energy on the tooth whitening effect of bleaching agent in vitro..Extracted human mandibular molars were sectioned to 2 fragments(mesial. distal) and lingual portions of crown were used in this study. All specimens were stained using a red wine for 24 hours and immersed in artificial saliva. Specimens divided into four groups, group 1 and 2 light-activated by LumaCool (LED, LumaLite, Inc., Spring Valley, USA), group 3 and 4 light-activated by FlipoWhite2 (Plasma acr lamp, Lokki. Australia). Group 1 and 3 bleached with Luma White (LumaLite, Inc., Spring Valley, USA), group 2 and 4 bleached with Polaoffice(SDI, Victoria, Australia). Bleaching treatment performed during 10 minutes every 24 hours and repeated 6 times. During bleaching treatment, distal fragments was light-activated (L) but mesial fragments was not(NL). Shade assessment employed before and after bleaching treatment using spectrophotometer. The results of the change in shade was compared and analysed between NL and L by using paired-sample T test with 95 % level of confidence. There were no significant differences between NL and L with a few exceptions. In group 2, $a^*$ value more change in L, in group 3, $b^*$ value more change in L, in group 4, $a^*$ value less change in L. After bleaching, $L^*$ value and ${\Delta}E$ increased in all groups and the value of $a^*$ and $b^*$ decreased in all groups. Within the limitation of this test conditions, the results of this study indicate that the light energy has no obvious improving impact on the tooth whitening effect of a bleaching agent.

• Restorative Dentistry and Endodontics
• /
• v.35 no.5
• /
• pp.380-386
• /
• 2010

Objectives: The introduction of nickel-titanium alloy endodontic instruments has greatly simplified shaping the root canal systems. However, these new instruments have several unexpected disadvantages. One of these is tendency to screw into the canal. In this study, the influence of taper on the screw-in effect of the Ni-Ti rotary instrument were evaluated. Materials and Methods: A total of 20 simulated root canals with an S-shaped curvature in clear resin blocks were divided into two groups. ProFile .02, .04, .06 (Dentsply-Maillefer) and GT rotary files .08, .10, .12 (Dentsply) were used in Profile group, and K3 .04, .06, .08, .10, and .12 (SybronEndo, Glendora) were used in K3 group. Files were used with a single pecking motion at a constant speed of 300 rpm. A special device was made to measure the force of screw-in effect. A dynamometer of the device recorded the screwin force during simulated canal preparation and the recorded data was stored in computer with designed software. The data were subjected to one-way ANOVA and Tukey's multiple range test for post-hoc test. p value of less than 0.05 was regarded significant. Results: The more tapered instruments generated more screw-in forces in Profile group (p < 0.05). In K3 group, 0.08, 0.10. and 0.12 tapered instruments showed more screw-in force than 0.04 tapered one, and 0.08 and 0.12 tapered instruments showed more screw-in force than 0.06 tapered one (p < 0.05). Conclusions: The more tapered instruments seems to produce more screw-in force. To avoid this screw-in force during instrumentation, more attention may be needed when using more tapered instruments.

• Restorative Dentistry and Endodontics
• /
• v.34 no.2
• /
• pp.130-136
• /
• 2009

The aim of this study was to develop a method for measuring the slumping resistance of flowable resin composites and to evaluate the efficacy using rheological methodology. Five commercial flowable composites (Aelitefil flow:AF, Filtek flow:FF, DenFil flow:DF, Tetric flow:TF and Revolution:RV) were used. Same volume of composites in a syringe was extruded on a glass slide using a custom-made loading device. The resin composites were allowed to slump for 10 seconds at $25^{\circ}C$ and light cured. The aspect ratio (height/diameter) of cone or dome shaped specimen was measured for estimating the slumping tendency of composites. The complex viscosity of each composite was measured by a dynamic oscillatory shear test as a function of angular frequency using a rheometer. To compare the slumping tendency of composites, one way-ANOVA and Turkey's post hoc test was performed for the aspect ratio at 95% confidence level. Regression analysis was performed to investigate the relationship between the complex viscosity and the aspect ratio. The results were as follows. 1. Slumping tendency based on the aspect ratio varied among the five materials (AF