• Restorative Dentistry and Endodontics
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• v.36 no.3
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• pp.238-242
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• 2011

Objectives: Palatogingival groove is a developmental anomaly that starts near the cingulum of the tooth and runs down the cementoenamel junction in apical direction, terminating at various depths along the roots. While frequently associated with periodontal pockets and bone loss, pulpal necrosis of these teeth may precipitate a combined endodontic-periodontal lesion. This case presents a case of a lateral incisor anatomically complicated with palatogingival groove. Methods: Two patients with lesion associated with the palatogingival groove were chosen for this report. Palatogingival grooves were treated with different restoration materials with endodontic treatment. Conclusions: Maxillary lateral incisor with a palatogingival groove may occur the periodontal disease with pulpal involvement. Elimination of groove may facilitate the periodontal re-attachment and prevent the recurrence.

• Restorative Dentistry and Endodontics
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• v.24 no.4
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• pp.604-613
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• 1999

This study was performed to evaluate the effect of resin and filler type on the fracture toughness of light-activated composites. Experimental composites were prepared using urethane tetramethacrylate(UTMA) and bisphenol glycidylmethacrylate(Bis-GMA) monomers and five different types of silica fillers. Fracture toughness was measured by a single edge V-notched beam(SEVNB) method, which was discussed from ASTM E399-78. Rectangular bars of $2.5{\times}5{\times}26mm$ were prepared with experimental composites and a notch about 2.25mm deep was carved at the center of the long axis of the specimen using a dental diamond disk driven by a dental micro engine. The flexural test was carried out at a crosshead speed of 0.05mm/min and fracture surfaces were observed under scanning electron microscope. The results obtained were summarized as follows: 1. The fracture toughness values of UTMA-based composites were relatively higher than those of Bis-GMA-based composites. 2. The highest fracture toughness value was observed in the UTMA-based composite containing the $1.5{\mu}m$-spherical fillers. 3 Aging in the distilled water at $37^{\circ}C$ for 10 days showed the increase of fracture toughness, which was severer in the Bis-GMA-based composites than those of UTMA-based composites. 4. The AE amplitude occurring during the fracture toughness tests was the highest at the point of macroscopic fracture.

• Journal of the korean academy of Pediatric Dentistry
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• v.25 no.1
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• pp.62-75
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• 1998

The main purpose of this study was to compare the anticariogenecity of glass ionomer restorative material polymerized by argon laser versus visible light, The results from the present study can be summarized as follows; 1. Under the polarized light microscope, the specimens of laser-cured group showed the shallower lesion body than that of visible-light cured group, both in the stage of lesion initiation and progression. 2. Glass ionomer material cured by visible light showed shallower body of lesion than that of composite resin cured by argon laser at the stage of lesion progression(p<0.05). It was suggested fluoride released from the glass ionomer might have the additive anticariogenic effect. 3. Statistical difference between groups on depth of lesion body was evident after lesion progression (p<0.05). It was suggested that anticariogenic effect by argon laser was more effective at the stage of lesion progression than the lesion initiation. 4. The increment of lesion body during progression was highest in group IV (p<0.05). 5. Based upon the above-mentioned results of this study, it can be concluded that the advantage of anticariogenic effect and short curing time of argon laser in glass ionomer polymerization should be considered in children and adolescents whose caries activity is relatively higher.

• Restorative Dentistry and Endodontics
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• v.29 no.3
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• pp.281-287
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• 2004

The purposes of this study were to evaluate the effect of adhesive property on microtensile bond strength and to determine the failure mode. Flat occlusal dentin surfaces were prepared using low-speed diamond saw. The dentin was etched with 37％ phosphoric acid. The following adhesives were applied to the etched dentin to manufacturer's directions： Scotchbond Multi-Purpose in group SM, Prime＆Bond NT in group NT, Scotchbond Multi-Purpose followed by Tetric-flow in group TR. After adhesive application, a cylinder of resin-based composite was built up on the occlusal surface. Each tooth was sectioned vertically to obtain the $1{\;}{\times}{\;}1\textrm{mm}^2$ "sticks". Microtensile bond strength were determined. Each specimen was observed under stereomicroscope and scanning electron microscope (SEM) to examine the failure mode. Data were analyzed using one way ANOVA. The results of this study were as follows：1. The microtensile bond strength value were：group SM ($18.98{\pm}3.01MPa$). group NT ($16.01{\pm}4.82MPa$) and group TR ($17.56{\pm}3.22MPa$). No significant statistical differences were observed among the groups (P>0.05). 2. Most of specimens showed mixed failure. In group TR, there was a higher number of specimens showing areas of cohesive failure in resin.

• Restorative Dentistry and Endodontics
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• v.28 no.6
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• pp.491-497
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• 2003

The purpose of this study was to evaluate the correlation between hybrid layer thickness and bond strength using confocal laser scanning microscope and microtensile bond strength test of two adhesive systems. The dentin surface of human molars. sectioned to remove the enamel from the occlusal surface. Either Scotchbond Multi-Purpose(3M Dental Product, St. Paul, MN, U.S.A) or Clearfil SE Bond (Kuraray, Osaka, Japan) was bonded to the surface. and covered with resin-composite. The resin-bonded teeth were serially sliced perpendicular to the adhesive interface to measure the hybrid layer thickness by confocal laser scanning microscope. The specimen were trimmed to give a bonded cross-sectional surface area of $1\textrm{mm}^2$, then the micro-tensile bone test was performed at a cross head speed of 1.0 mm/min. All fractured surfaces were also observed by stereomicroscope. There was no significant differences in bond strengths the materials(p>0.05). However. the hybrid layers of three-step dentin adhesive system, SM, had significantly thicker than self-etching adhesive system. CS(p<0.05). Pearson's correlation coefficient showed no correlation between hybrid layer thickness and bond strengths(p>0.05). Bond strengths of dentin adhesive systems were not dependent on the thickness of hybrid layer.

• Restorative Dentistry and Endodontics
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• v.25 no.1
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• pp.78-84
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• 2000

The aim of this study was to compare shaping ability of nickel-titanium rotary files with different taper in simulated resin canals. The instruments used in this study were GT with .04 taper ProFile with ISO-sized tip, .04 taper ProFile with ISO-sized tip alone, and .02 taper Naviflex file and all canals were prepared by crown-down technique. A total of 30 composite images were made from pre- and post-canal scanned images using Scanjet 4C scanner and Corel photopaint 8.0 and then, prevalence of canal aberrations was measured. The amount of coronal substance the instruments removed was also calculated two-dimensionally on digitized images with the Brain C software to compare the relative enlarging efficiency. Finally, the prepared internal canal form was evaluated three-dimensionally with impression technique. The results were as follows; 1. The incidence of zipping in Naviflex group was significantly high compared to the other two groups(P<.05). 2. The amount of coronal substance the GT combined group removed was significantly larger than the other two groups(P<.05). 3. The GT combined group produced canals with good taper and flow. Under the conditionas of this study, the combined use of larger tapered nickel-titanium rotary files prepared simulated canals safely, efficiently and with good three-dimensional form.

• Restorative Dentistry and Endodontics
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• v.42 no.3
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• pp.188-199
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• 2017

Objectives: This in vitro study evaluated the effect of dentin biomodifiers on the immediate and long-term bond strengths of a simplified etch and rinse adhesive to dentin. Materials and Methods: Flat coronal dentin surfaces were prepared in 120 extracted human molars. Teeth were randomly divided into 5 groups (n = 24) according to 5 different surface pre-treatments: No pre-treatment (control); 1M carbodiimide (EDC); 0.1% epigallocatechin-3-gallate (EGCG); 2% minocycline (MI); 10% sodium ascorbate (SA). After surface pre-treatment, adhesive (Adper Single Bond 2 [SB], 3M ESPE) was applied. Composite was applied into transparent plastic tubes (2.5 mm in diameter), which was placed over the bonded dentin surface. From each group, 10 samples were subjected to shear bond strength (SBS) evaluation at 24 hours (immediate) and remaining 10 samples were tested after 6 months (delayed). Additionally, 4 samples per group were subjected to scanning electron microscopic analysis for observation of resin-dentin interface. The data were statistically analysed with Shaperio-Wilk W test, 2-way analysis of variance (ANOVA), and post hoc Tukey's test. Results: At 24 hours, SBS of all surface pre-treatment groups were comparable with the control group, with significant differences found between EDC and SA groups only (p = 0.009). After 6 months storage, EDC, EGCG, and MI pre-treatments preserved the resindentin bond strength with no significant fall. Conclusions: Dentin pre-treatment with all the dentin biomodifiers except SA resulted in significant preservation of resin-dentin bond over 6 months storage period, without negatively affecting the immediate bond strength of the etch and rinse adhesive tested.

• Restorative Dentistry and Endodontics
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• v.21 no.2
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• pp.569-584
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• 1996

The purpose of this study was to elucidate the effect of benzalkonium chloride on tensile bond strength of BPDM/HEMA dentin bonding. One hundred sixty dentin specimens from freshly extracted bovine mandibular incisors were used, and 0, 0.02, 0.1 or 0.5% benzalkonium chloride solution was applied to the dentin specimen with/after phosphoric acid. 32% phosphoric acid was used when the specimens were bonded with One-Step$^{TM}$, a BPDM/HEMA system and 10% was used when bonded with All-Bond$^{(R)}$ 2, a NTG-GMA/BPDM system. Aelitefil$^{TM}$ composite resin was bonded to the pretreated dentin specimen with the use of All-Bond$^{(R)}$ 2 or One-Step$^{TM}$ dentin bonding agent. After the bonded specimens were stored in $37^{\circ}C$ distilled water for 24 hours, tensile bond strength was measured. The fractured dentin specimens were examined under the scanning electron microscope. The results were as follows : Benzalkonium chloride application after acid-treatment resulted in decrease of dentin bond strength of One-Step$^{TM}$, a BPDM/HEMA system (p>0.05). Benzalkonium chloride application did not exert any influence on dentin bond strength of All-Bond$^{(R)}$ 2, a NTG-GMA/BPDM system (p>0.05). There was no relationship between the concentration or application method of benzalkonium chloride and the dentin bond strength of One-Step$^{TM}$ or All-Bon$^{(R)}$ 2 (p<0.05). On SEM examination of the fractured dentin-resin interface, while mixed failure was prominent in dentin bonding with One-Step$^{TM}$, adhesive and mixed failures were seen together in dentin bonding with All-Bond$^{(R)}$ 2 regardless of the concentration and application method of benzalkonium chloride.

• Journal of the korean academy of Pediatric Dentistry
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• v.46 no.3
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• pp.328-336
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• 2019

The purpose of this study is to analyze the changes in patient distribution and practice pattern resulted from changes of socioeconomic circumstances. From January 2008 to December 2017, information about patient distribution and practice pattern was collected and reviewed. Both the number of new patients and revisiting patients increased. The average age of new patients showed a declining trend. Children aged between 0 and 6 had the majority. In case of restorative treatment, the use of composite resin decreased, whereas resin modified glass ionomer increased. As to pulp treatment of primary tooth, the proportion of pulpectomy increased significantly, but decreased in pulpotomy. The results showed an increase in the treatments under sedation and general anesthesia and with the use of midazolam and nitric oxide increased after 2014.

• Restorative Dentistry and Endodontics
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• v.44 no.2
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• pp.13.1-13.9
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• 2019

Objectives: This study evaluated the effect of dentin pretreatment with silver nanoparticles (SNPs) and chlorhexidine (CHX) on the microshear bond strength (${\mu}SBS$) durability of different adhesives to dentin. Materials and Methods: Occlusal surfaces of 120 human molars were ground to expose flat dentin surfaces. The specimens were randomly assigned to six groups (n = 20). Three groups (A, B, and C) were bonded with Adper Single Bond 2 (SB) and the other groups (D, E, and F) were bonded with Clearfil SE Bond (SEB). Dentin was pretreated with CHX in groups B and E, and with SNPs in groups C and F. The specimens were restored with Z250 composite. Half of the bonded surfaces in each group underwent ${\mu}SBS$ testing after 24 hours and the other half was tested after 6 months of water storage. Results: SNP application was associated with a higher ${\mu}SBS$ than was observed in the CHX and control groups for SEB after 24 hours (p < 0.05). A significantly lower ${\mu}SBS$ was observed when no dentin pretreatment was applied compared to dentin pretreatment with CHX and SNPs for SB after 24 hours (p < 0.05). The ${\mu}SBS$ values of the 6-month specimens were significantly lower than those obtained from the 24-hour specimens for all groups (p < 0.05). This decrease was much more pronounced when both adhesives were used without any dentin pretreatment (p < 0.05). Conclusions: SNPs and CHX reduced the degradation of resin-dentin bonds over a 6-month period for both adhesive systems.