• 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.

• Restorative Dentistry and Endodontics
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• v.12 no.1
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• pp.65-76
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• 1986

Carious dentin can be classified, on the basis of their clinical characteristics, into three groups; sound, sclerotic and active carious dentin. Active carious dentin differs from sclerotic dentin by its abscence of variable bacteria within tubles and amount of chemical content. But the apatite molecules of active carious dentin are not fully studied. The purpose of this study was to observed the physico-chemical characteristics of deep carious dentin. The samples of sound, sclerotic and active carious dentin were obtained respectively from 300 freshly extracted carious teeth. Bacterial-rich zone of superficial soft dentin layer was removed with hand instruments from all samples in advance. The samples were powdered and sieved (200 mesh) before analyses. Identification and estimation of the crystallinity of the samples were carried with X-ray diffraction and infrared absorption analyses. Measurements were made on a Rigaku Denki (Rigaku, geiger flex III, Japan) X-ray diffractometer with Cu-target at 30 Kv, 30 mA and are traced on a monochromatic tracer. Infrared absorption analysis was made on FT-IR spectrophometer (Nicolet Instrument Co.) using KBr pellets containing the samples and was recorded on data process (Model IR-80. Nicolet Instrument, Co). The following conclusions were as follows; 1. The nature of the main inorganic structure of sound, sclerotic and active carious dentin proved to be hydroxyapatite. 2. It was difficult to determine the identification due to their crystallinity of sound, sclerotic and active carious dentin. But sound dentin was the highest in crystallinity among them. 3. The magnesium whitlockite was to be found in active carious dentin, but not in sound and sclerotic dentin. 4. The carbonate content was highest in sound dentin, but the lowest was in active carious dentin.

• 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.

• Proceedings of the KACD Conference
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• 2003.11a
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• pp.624-624
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• 2003

I. Objectives The purpose of this study was to investigate the ultrastructure of sclerotic dentin of non-carious cervical lesions after acid etching. II. Materials and methods Teeth with non-carious cervical lesions were collected and dentinal surfaces were acid etched with 35% phosphoric acid. The micromorphological features of peritubular dentin and intra-tubular calcific structure were observed with scanning electron microscope.(omitted)

• Restorative Dentistry and Endodontics
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• v.26 no.1
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• pp.51-63
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• 2001

In order to know the effect of dentin bonding agents on the restoration of cervical abrasion, Scotchbond Multipurpose Single Bond and Clearfil Liner Bond 2 were used in 51 teeth with abrasion lesion and normal teeth. The surface structure and dentinal tubules of acid etched dentin and resin replica were examined using scanning electron microscopy. The interfacial morphology between dentin and adhesives was investigated by confocal laser scanning microscopy. Following results were obtained. 1. The hybrid layer and resin tag of the dentin showing cross-sectional surface of dentinal tubules are thicker and longer than those of dentin showing oblique surface of dentinal tubules. 2. The sclerotic cast was frequently observed in dentinal tubule, and the cast looked like cuboidal or rhomboidal-shaped crystals clumped from outer side to inner side. 3. The formation of hybrid layer and resin tag was the most prominent in Scotchbond Multipurpose group, whereas Clearfil Liner Bond 2 group showed very poor formation. The formation of hybrid layer and resin tag in Single Bond group was less than Scotchbond Multipurpose group.

• Journal of the korean academy of Pediatric Dentistry
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• v.23 no.4
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• pp.954-967
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• 1996

Laser application to modify healthy permanent dentin to improve microhardness and caries resistence has been previously reported but the physical modification and ablation thresholds of carious and sclerotic dentin has yet to be identified. This study determined the energy density required by modify (physical modification threshold, PMT) and remove (ablation threshold, AT) infected carious, affected and selerotic dentin compared to healthy permanent dentin. $1{\pm}0.25mm$ thick dentin sections(n=272) from extracted human teeth were used. Smear layer was removed 0.5M EDTA for 2 minutes. Utilizing three pulsed fiberopitc delivered contact lasers with different emission wavelengths($1.06{\mu}m$=Nd : YAG, $2.10{\mu}m$=Ho : YAG and $2.94{\mu}mEr$ : YAG). The energy density($J/cm^2$) was incrementally increased and the resulting tissue interaction classified on a scale from 0-6. A minimum of 5 repetitions/energy density were completed. Light microscopy(10-25X) was used to verify the physical modification(scale=3) and ablation thresholds(scale=4) of the various forms of dentin and the data were analyzed by logistic regression at the 95 % confidence interval. PMT and AT by the laser and the dentin types were: PMT and AT was lower in infected dentin than in sound dentin for all lasers. PMT and AT induced by Nd : YAG>Ho : YAG>Er : YAG for all forms of dentin. Microhardness was increased in sound dentin at PMT. Morphology of crater examined by light microscopy showed Nd : YAG was safe and effective for removing carious dentin and Er: YAG was effective for removing sound dentin. The PMT and AT for YAG lasers are different as a function of dentin type which may be utilized for selective modification and removal of dentin.