• Restorative Dentistry and Endodontics
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• v.22 no.1
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• pp.228-243
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• 1997

The changes of microstructures, morphology of sclerotic dentin and bonding aspects generated by an adhesive resin was investigated. Incisors and premolars showing natural cervical abrasions were collected and conditioned with 10 % phosphoric acid or 10 % maleic acid. The sclerotic dentin specimens were then rinsed and blot-dried and applied with dentin adhesive (All Bond 2) to the conditioned dentin surface. To examine the morphologic change of the sclerotic dentin specimen after etching and bonding procedure, the treated specimens were examined by SEM. To analyze the chemical composition of sclerotic dentin and crystals occluding dentinal tubules, the sclerotic dentin specimen was powdered and examined with X-ray Diffractometer. To investigate the Ca/P weight percent ratio within the dentinal tubules, the sclerotic dentin specimen was fractured perpendicularly to the long axis of the tooth from the center of cervical abrasion lesion and then examined with EDX(Energy Dispersive X-ray) microanalyzer. The results were as follows : 1. The increased width of peritubular dentin and the depositions of the irregular amorphous materials within the dentinal tubules were showed in the sclerotic dentin specimens. 2. After the treatment of sclerotic dentin specimen with 10 % phosphoric acid or 10 % maleic acid, the lateral side of tubules rather than cross-sectional tubule openings was showed exclusively at the incisal and gingival incline of the specimens. 3. After the treatment of sclerotic dentin specimen with 10 % phosphoric acid or 10 % maleic acid, the hybrid layer was not formed evidently and the resin tag was not formed or shortly penetrated into the tubules with the thinner diameter. 4. According to the results of XRD analysis of the sclerotic dentin specimen, Hydroxyapatite and Octacalcium phosphate were predominent, however, Whitlockite crystals were rare. 5. The mean Ca/P weight percent ratio analysed from 5 fractured sclerotic dentin specimens was $2.322{\pm}0.170$ at the intertubular dentin, $1.826{\pm}0.051$ within the dentinal tubule.

• The Journal of the Korean dental association
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• v.54 no.11
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• pp.865-873
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• 2016

Background/Purpose: The purpose of this study was to evaluate the effect of Nd:YAG irradiation on adherence of retrograde filling materials (mineral trioxide aggregate [MTA] and Super-EBA) by micro-computed tomography (CT) measurement and to observe the dentinal surface after irradiation by scanning electron microscopy (SEM). Materials and methods: Forty retrofilling models using extracted human teeth were divided into four groups according to the material and method used: ProRoot MTA (MTA group), Super-EBA (EBA group), MTA with Nd:YAG laser irradiation (LMTA group), and Super-EBA with Nd:YAG laser irradiation (LEBA group). All specimens were stored in 100% humidity for 24 hours until micro-CT was performed. The gap volume of the tooth/material interface was measured using the CTAn program. In six samples, the laser-irradiated dentin surface was observed using SEM. Results: The mean percent difference in gap volume was not statistically significant between the Nd:YAG laser-irradiated groups and non-irradiated in both materials(P > 0.05). The gap volume in the MTA group was significantly lower than that in the EBA group (P < 0.05). Examination of the non-irradiated specimens by SEM showed patent dentinal tubules. In contrast, alterations in the texture of the dentin surface and obliteration of the dentinal tubules were evident in the Nd:YAG laser-irradiated specimens. Conclusion: In this study, changes in the dentinal surface after Nd:YAG irradiation did not affect adherence between the apical filling material and the dentin wall.

• Restorative Dentistry and Endodontics
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• v.19 no.1
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• pp.45-63
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• 1994

128 freshly extracted human molars were used to study the interaction between dentinal smear layer removal with various agents, and the shear bond strength of a light cured glass ionomer cement to dentin. It was proposed that the removal of smear layers using acidic cleaners followed by incorporation of Fe mordant with dentin could enhanced the infiltration of monomer component in light curing glass ionomer cement and resulted in a high bond strength. For the first treatment process for removal of smear layers on the surfaces of dentin, 50 % citric acid, 10% maleic acid and 10 % phosphoric acid were used, and for the second treatment process, 15% ferric chloride, 6.8% ferric oxalate or 30% potassium oxalate were used. Distilled water was used as a control. After double sequential treatment on dentin, a light curing glass ionomer cement was bonded to dentin. After being immersed in water at 31'C for 24 hours, shear bond strengths were measured Instron testing machine(Model No.4202, USA). Surface changes were also observed using SEM (Hitachi, S-2300, Japan) after treatment process with each agents. The following conclusions were drawn : 1. Dentin surface cleaned with maleic acid and treated with ferric oxalate showed the highest bond strength with light curing glass ionomer cement. 2. Bond strengths of glass ionomer cement to dentin treated with maleic acid or citric acid were the highest, and that treated with phosphoric acid showed the lowest. 3. The effect of ferric oxalate on shear bond strength to dentin was always higher than that of ferric chloride. 4. The smear layers were clearly removed and the orifices of dentinal tubules were opened widely by the citric acid, maleic acid and phosphoric acid. 5. The orifices of dentinal tubules opened after using the first solution were closed with the treatment of ferric chloride. 6. The precipitate like crystals were formed on dentin surfaces and tubules, but a significant decrease in bond strength of glass ionomer cement to dentin surface treated with potassium oxalate.

• Restorative Dentistry and Endodontics
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• v.16 no.2
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• pp.155-164
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• 1991

The purpose of this study was to evaluate the effects of bleaching agent through the dentinal tubules of cervical area in the intracoronal bleaching of pulpless teeth on cutured fibroblast cells. Extracted human incisors were enlarged to # 40 K-file and obturated with gutta-perella and AH 26 sealer. The gutta-percha was removed to 2mm below the cementoenamel junction of the root The teeth were divided into 3 experimental and control groups. Experimental groups; Experimental group 1: Temporary inlay wax filld with 30% $H_2O_2$ in pulp cavity. Experimental group 2: Temporary inlay wax filld with 30% $H_2O_2$ in pulp cavity after placement of ZOE cement to cementoenamel junction. Experimental group 3: Temporary inlay wax filld with 30% $H_2O_2$ in pulp cavity after application of Copalite to cementoenamel junction. Control group: Temporary inlay wax filled without 30% $H_2O_2$ in pulp cavity under the same condition at each experimental group. Each tooth was immersed in well of multidish cultured fibroblast cell for 48 hours. The cellular multiplication and cell viability were calculated at the interval of 1, 3, 5. 7 hours and the morphological changes in well were observed and their photographs were taken with inverted microscope. The obtained results were as follows : CD The cellurar multiplicaton and cell viability decreased in all experimental groups at 1 hour after experiment and the morphology of fibroblast cell was changed from star shape to round (2) The cell viability was lowered to 34 % in experemental group 1, 44 % in experimental group 2, and 38 % in experemental group 3 at 3 hours after experiment (3) The cell multiplication was decreased to 54% in experemental group 1. 47% in experimental group 2, and 40% in experemental group 3 at 7 hours after experiment. (4) The decrease of cell number and morphological changes of fibroblast cell were remarkable in experimental group 1, group 3 and 2 in order. These results suggest that the fibroblast cells receive severe damage by 30% $H_2O_2$ solution leaked through the dentinal tubules and the dentinal tubules are able to be obturated better by ZOE cement than by Copalite.

• Restorative Dentistry and Endodontics
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• v.30 no.5
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• pp.385-392
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• 2005

The purpose of this study was to observe the effect of canal filling on the bacteria left in the dentinal tubules and to compare the sealing ability between Gutta-percha and Resilon. The bovine dentin block models were prepared E. faecalis was inoculated to dentin blocks and incubated. The dentin blocks were divided into 5 groups. Group 1 was the negative control. Group 2 was the positive control. Group 3 was filled with ZOE based sealer and Gutta-percha, Group 4 with resin based sealer and Gutta-percha, and Group 5 with resin based sealer and Resilon. After 24 hour, the blocks were incubated at $37^{\circ}C$ for 1, 2, 3 and 4 weeks on BHI agar plates. The internal dentin portion of the blocks was removed using ISO 027, 029, 031, 035 round burs and the dentin chips were incubated at $37^{\circ}C$ for 24 hour Following incubation, the optical density of the medium was measured. The data were statistically analysed using repeated measures ANOVA and one-way ANOVA. The results were as follows, 1. There. was statistically significant reduction in the number of E. faecalis of the group where dentinal tubules were completely sealed with nail varnish in comparison with the groups obturated with gutta-percha or resilon (p < 0.05). 2. In group 5, the number of E. faecalis in the dentinal tubules decreased significantly with time (p < 0.05). whereas in Group 3 and 4, there was no reduction in its number (p > 0.05). 3. Under the conditions of this experiment, E. faecalis survived up to 4 weeks after obturation with gutta-percha or resilon (p > 0.05).

• Journal of Oral Medicine and Pain
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• v.24 no.4
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• pp.397-410
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• 1999

In order to obtain the basic data concerning the optimal parameters in using Nd:YAG laser as a therapeutic modality to dentinal hypersensitivity, the author prepared 3 sections of sound dentin and 10 sections of sclerotic dentin with thickness of $0.5mm{\pm}0.1mm$ from human extracted teeth of anteriors and premolars, and applied the laser energy from a fiberoptic delivered, free running, pulsed Nd:YAG laser (wavelength 1064nm, pulse duration $120{\mu}sec$, fiber diameter $320{\mu}m$) to surfaces of sound and sclerotic dentin sections for 1 second with contact/unidirectional moving mode of the fiber under speed of 3mm~4mm/sec and parameters of 0.5W/10Hz, 1.0W/10Hz, 1.5W/10Hz, 2.0W/10Hz: $62J/cm^2$, $124J/cm^2$, $187J/cm^2$, $249J/cm^2$. The author comparatively evaluated the characteristics of ultrastructural changes on surfaces of sound and sclerotic dentin sections irradiated by the pulsed Nd:YAG laser using the scanning electron microscopy. A fairly ill-defined bordered surface of partially closed and melted dentinal tubules can be seen on the scanning electron microscopic feature of the sound dentin surface irradiated by the pulsed Nd:YAG laser with energy density of $62J/cm^2$. The physical modification of sound dentin surface extensively occurred depended on the increase of energy density from $62J/cm^2$ to $124J/cm^2$, $187J/cm^2$, $249J/cm^2$. While, a fairly well-defined bordered surface of partially closed and melted dentinal tubules with thickened peritubular dentin can be seen on the scanning electron microscopic feature of the sclerotic dentin surface irradiated by the pulsed Nd:YAG laser with energy density of $62J/cm^2$. The physical modification of sclerotic dentin surface of a fairly rough, shallow depression with many cracks, thickened peritubular dentin and structureless dentinal tubules extensively occurred depended on the increase of energy density from $62J/cm^2$ to $124J/cm^2$, $187J/cm^2$, $249J/cm^2$ compared to those of sound dentin surface irradiated by the pulsed Nd:YAG laser under the same parameters. Therefore, it is recommended that the pulsed Nd:YAG laser as a therapeutic modality to dentinal hypersensitivity should be applied with the less energy density than $62J/cm^2$ on the sound dentin surface, and its energy density on the partially sclerotic dentin surface should be lower than that on the sound dentin surface to preserve tooth from unnecessary excessive structural destruction.

• Journal of dental hygiene science
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• v.11 no.5
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• pp.431-436
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• 2011

The aim of this study was to compare the effects of the short-term use of the desensitizing dentifrices marketed in Korea in vitro. Fifty human dentine specimens were wet ground with silicone carbide paper and etched with 6% citric acid for 90 seconds to allow complete opening of the dentinal tubule. Ten specimens from each group were brushed for 50 and 150 strokes with a V8 Cross Brushing Machine(Sabri Co., U. S. A). All the specimens were evaluated by SEM(${\times}3000$). The degree of occlusion of the dentinal tubules was quantified using an image analyzer. The results were analyzed by one-way ANOVA and Tukey's multiple comparisons using Window SPSS. The dentifrices containing nano-carbonate apatite, potassium nitrate and hydroxyapatite showed significantly higher occlusion effects than the other dentifrices after toothbrushing for 50 strokes(p<0.05). The Sensodyne freshmint$^{(R)}$dentifrice showed 34% fewer open tubular areas compared with the Sensodyne original$^{(R)}$dentifrice for 50 strokes. According to the short-term use of desensitizing dentifrices, the dentifrices containing nano-carbonate apatite, potassium nitrate and hydroxyapatite were most effective in occluding the dentinal tubules.

• Journal of dental hygiene science
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• v.16 no.4
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• pp.272-283
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• 2016

This study compared and analyzed the occluding effects of fluoride compounds and desensitizers, which are commonly used in dental clinics, on dentinal tubules. This study also evaluated the persistence of the active ingredients over time by performing toothbrushing with an electric toothbrush. Thirty-five molar teeth, which had been extracted within the past 3 months from healthy people without tooth decays, amalgam fillings, or dental crowns, were divided into 4 pieces each. Of these, 135 teeth pieces were used as study specimens. These specimens were divided into a control group, an untreated group, and 5 experimental groups (acidulated fluoride gel, fluoride varnish, Gluma, Super Seal, and SE-Bond). The specimens were then subjected to toothbrushing equivalent to 1 week (140 times), 2 weeks (280 times), and 4 weeks (560 times), and the occluding effects on dentinal tubules in 3 regions of each specimen were examined under a scanning electron microscope. The fluoride varnish treated group showed the highest degree of dentinal tubule occlusion effects during the first, second, and fourth weeks of toothbrushing, with the SE-Bond treated group showing the second highest degree and the Gluma treated group showing the lowest degree. After 4 weeks of toothbrushing, the Gluma treated group and the Super Seal treated group showed the lowest degrees of dentinal tubule occlusion effects. In summary, the fluoride varnish treated group and the SE-Bond treated group displayed higher occlusion effects even after 4 weeks of treatment than did the other experimental groups. Therefore, it is the authors' belief that fluoride varnish and SE-Bond are effective for treating dentinal hyperesthesia.

• The Journal of the Korean dental association
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• v.48 no.6
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• pp.469-477
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• 2010

The purpose of this study was to evaluate the effect of two dentin desensitizers and Er,Cr:YSGG laser for dentinal tubule occlusion. Twenty recently extracted single-rooted human teeth were used to obtain root dentinal fragments. The crowns were cut approximately 1mm below the cementum enamel junction(CEJ). A second cut was used to remove the apex of the root. Subsequently, a longitudinal cut was made in order to obtain 2 fragments from each root sample. The cementum from the cervical portion was removed using a high-speed diamond-coated bur in order to expose the dentin. To open dentinal tubules, forty samples were treated with 50% citric acid for 2 min and then rinsed under distilled water for 1 min. These were divided into four groups of ten samples each. The first group served as a control group. In group 2, the samples were irradiated with the Er,Cr:YSGG laser(Waterlase MD, Biolase, USA). In group 3, the samples were treated with Bisblock and ONE-STEP PLUS(Bisco, USA). In group 4, the samples were treated with Gluma comfort bond & Desensitizer(Heraeus Kulzer, Germany). All the samples were examined using Scanning electron microscopy(Hitachi, S-4700, Japan) with two different magnifications(X2000, X5000). These images were assessed by one examiner who was blind to the experimental procedure, using the index of smear layer removal. The distribution of smear layer removal grades was tested using Fisher's exact test. On the order hand, in order to evaluate the occluding effect of two dentin desensitizers and Er,Cr:YSGG laser, the number of exposed dentinal tubules was counted in each group. These were evaluated using the Kruskal-Wallis test with significance predetermined $\alpha$=0.05. There were statistically significant differences between the three groups(Er,Cr:YSGG laser, Bisblock+ONE-STEP PLUS, Gluma comfort bond & Desensitizer) and control group.

• Journal of Periodontal and Implant Science
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• v.27 no.3
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• pp.469-478
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• 1997

The purpose of this study was to evaluate the structural change of root surface and the occlusion of dentinal tubule following $CO_2$ laser treatment. Seven extracted healthy human premolar werw curetted, sectioned, and four specimens were randomly assigned to each of 6 different treatment groups : 1) untreated EDTA etched control: 2) root plande only: 3) $CO_2$ laser treated with 2W mode 6(10msec/pulse, 20pps) for 1 minute: 4) $CO_2$ laser treated with 2W mode 6(lOmsec/pulse, 20pps) for 2 minutes: 5) $CO_2$ laser treated with 2W mode 7(20msec/pulse, 20pps) for 1 minute: 6) $CO_2$ laser treated with 2W mode 7(20msec/pulse, 20pps) for 2 minutes. Following the prescribed treatment, the specimens were prepared for SEM evaluation. Results showed that $CO_2$ laser may be effective to occlude dentinal tubules tor dentin sensitivity treatment. The effect of dentinal tubule occlusion was enhanced with increasing the total energy level lased to specimen regardless of lasing mode. The structural changes of root surfaces were restricted to superficies, and these changes included fissuring, charring, crater formation over the smooth lava like texture. The charring and crater formation implying root damage was observed in the case of the longer duration of a pulse. The results of the present study suggests that the pulsed $CO_2$ laser with shorter pulse duration and longer exposure time can be used effectively in order to obtain the optimal dentinal tubule occlusion with minimal root damage.