The aim of this study was to evaluate the surface pH of active or arrested carious dentin using a newly developed micro-pH sensor, and to compare the relationship between different pH measuring techniques. Twenty extracted human teeth with a moderate to severe degree of dentinal caries were divided into two groups, acute or chronic caries. The surface pH values of carious dentin were measured using three methods: surface pH of extracted teeth was directly measured using the micro-pH sensor through the sponge (Direct); surface pH of sliced extracted teeth was measured using pH-Imaging technique (Imaging) or the micro-pH sensor (Slice). Results were statistically analyzed by Cohen's kappa test. For all techniques, the pH values of the caries part in acute and chronic carious dentin (5.3-6.5) were statistically lower than those of intact dentin (6.9-7.4). Comparison of Imaging and Slice methods, which measured the same pH point, a high agreement (κ=0.78) was confirmed. However, the surface pH of direct measurement of carious dentin was higher than those of the other two methods. For all technique, there were statistical significances on pH values between active and arrested dentinal caries. Because this micro-pH sensor can evaluate caries activity on a tooth, it might have the potential to assist in assessment of carious lesions and clinical treatment using MI concepts.

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The purpose of this study was to observe the surface of the set paste/paste type light-cured restorative glass ionomer cement “Fujifil LC” and to observe the interfacial ultrastructure between the cement and the tooth tissues under the FE-SEM. This glass ionomer cement was improved in the transparency after light curing and in the mixing procedure. The matrix ratio of the set Fujifil LC cement surface was larger than the traditional restorative cement surface. The cement-tooth junction was very tight showing no gap formation, and the hybrid layer about 0.3μm in thickness was observed at the superficial dentin layer. We think that the Fujiil LC glass ionomer cement can clinically achieve the satisfying aesthetic restorations.

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The purpose of this study was to investigate the relationship between the cervical lesions and age of the patients, brushing methods and bruxism through the clinical survey with the first appointment patients. We surveyed 209 first appointment patients (male: 118, female: 91) who had unfilled cervical lesions from August in 2002 to July in 2004. Evaluation items were, (1) age of the patients, (2) classification of the cervical lesions (Angular shape or Saucer shape), (3) the way of brushing (frequency per day, methods and use of dental paste), (4) bruxism. The number of the cervical lesions found were 475 cases of angular shape and 658 cases of saucer shape. The mean number of the cervical lesions in each generation was 1.75 cases (22-29y), 5.52 cases (30-39y), 4.58 cases (40-49y), 6.19 cases (50-59y), 5.59 cases (60-69y), or 5.12 cases (70-83y), respectively. Also, the following results were found; 1) the cervical lesions developed at the first premolar, 2) a habit of bruxism was associated with the increase in lesions, 3) the other items had no influence on the development of cervical lesions. Further research was necessary to investigate the relationship between the appearance and development of the cervical lesions and brushing.

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It can be considered that the form and dimensions of the test piece for the micro-tensile bond test (MIT) affect both the value of bond strength and the break starting position.
The purpose of this study was to examine the effect of cross sectioned form (width×thickness) on the microtensile bond strength (μ-TBS) of beam specimen for MIT.
Standardized class I cavity was prepared in 12 human extracted upper molars, and was restored clinically with a resin composite restorative system. The restored specimens were divided into three groups for preparing test piece, i.e., two types of beam specimen having a rectangular cross sectioned form: 1.2×0.8 mm or 0.8×1.2 mm and a beam specimen having a square cross sectioned f orm: 1.0×1.0 mm, and those three types of beam specimen (n=15 each) were subjected to MIT.
The fracture mode of the specimen after MIT was observed using a digital microscope and a scanning electron microscope. The beam specimen having a square cross sectioned form (1.0×1.0 mm) was effective to gain the essential bond strength and to improve the reliability of experiment in comparison with the beam specimen having a rectangular cross sectioned form (1.2×0.8 mm, 0.8×1.2 mm). The fracture mode of the specimen after MIT was mainly mixed fracture consisting of interfacial fracture between adhesive layer and dentin and cohesive fracture in the adhesive layer, regardless of specimen form.

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Argon ion (Ar-ion) etching have been widely employed as SEM observation of resin-dentin interface, describing hybrid layer as composed of a meshwork structure. However, it is not clear if this meshwork is resin or collagen fiber. The purpose of this study was to examine the meshwork after Ar-ion etching by FE-SEM. Dentin discs were prepared from extracted human molars, the surfaces were etched for 60 seconds with H₃PO₄. These surfaces were treated with Clearfil MEGA BOND (Kuraray Medical) following manufacturer's directions. Specimens were restored with a flowable resin, longitudinally sectioned through the resin-dentin interface after 1 day water storage and the surface polished with diamond paste. Specimen was Ar-ion etched for 30 seconds, and observed by FESEM. The specimen was then treated with 10 % NaOC1 for 1 minute and 10-3 solution for 1 second. Same area was observed after each treatment. The resin-dentin interface demonstrated meshwork after Ar-ion etching. However, following Na0Cl or 10-3 treatment, the meshwork configuration had changed and partially disappeared from the interface between the remained meshwork and dentin substrate. Our data suggested the meshwork structure on by Ar-ion etched resin-dentin interface was composed of polymerized primer and bonding resin, hybrid layer and partially exposed collagen fibers.

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The objective of the current study was to investigate the effect of surface modification on bond strength and durability between zirconia implant abutment and heat-pressed ceramic superstructure. A zirconia material designed for abutments (ZiReal Post) and a ceramic material for tooth-colored restorations (IPS Empress) were employed as the adherend materials. The Variolink II composite-based material was used as the luting agent. The zirconia abutment surface preparations were; 1) wet-grinding with SiC paper, 2) Etching with 5% hydrofluoric acid for 60 seconds, 3) air-abrasion with alumina for 23 seconds, and 4) tribochemical silica coating with the Rocatec System, whereas the two priming conditions were; a) priming with the proprietary silane primer for the luting agent (Monobond-S), and b) no silane priming. The zirconia abutment and heat-pressed ceramic materials were bonded together with luting agent. Shear bond strengths were determined both before and after thermocycling (5 and 55°C, 20, 000 cycles).
Mechanical retention is an important factor for adhesive bonding to zirconia abutment. Application of the Rocatec System was effective for enhancing bond strength to the zirconia material of the Variolink II luting agent. Combined use of tribochemical silica coating with Rocatec System and silane primer produced the greatest bond strength.

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This study examined marginal gap formation of new luting cements (HY-BOND ResiGlass^®, Shofu; Ionotite F^®, Tokuyama Dental; Vitremer Luting Cement Fast Set^®, 3M ESPE; Fuji Luting^® and Fuji Plus^®, GC) as controls. This study also examined the shear bond strength to human dentin substrate, the flexural properties (strength and modulus of elasticity), which may influence the gap formation.
Although the sum of marginal gap width and the value of flexural strength of Fuji Plus^® and HY-BOND ResiGlass^® were no significant difference, the values of shear bond strength and flexural modulus of elasticity of Fuji Plus^® were significantly higher compared with those of HY-BOND ResiGlass^®. The sum of marginal gap width and the values of shear bond strength and flexural strength showed no significant difference among Ionotite F^®, Vitremer Luting Cement Fast Set^® and Fuji Luting^®.

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This study was aimed to evaluate the bonding efficacy of a one-bottle one-step adhesive system G-BOND. Tensile bond strengths (TBS) to bovine enamel and dentin were 16.6±3.7MPa and 13.2±3.4MPa, respectively. The TBSs were not affected either with 20, 000-times thermocycling or with different light sources (Halogen, Plasma arc and LED)(p>0.05). Microtensile bond strengths (μ TBS) to bovine enamel and dentin were 30.3±11.7MPa and 46.4±6.5MPa, respectively.μ TBS to human dentin was 52.0±10.6MPa. FE-SEM and TEM observations in human teeth presented the tight adhesions to enamel, sound dentin and caries-affected dentin. An interfacial structure of approximately 0.6μm thick was found between adhesive resin and dentin, presuming that a nano-leveled bonding mechanism could possibly be created.

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Recently, the resin bonding system has been simplified to shorten the clinical procedures. Each manufacturer developed one bottle/one step type resin bonding systems. The purpose of this study was to examine the nanoleakage of four one-bottle/one-step bonding systems under the FE-SEM, using the silver nitrate staining technique. Cervical saucer-shaped class 5 cavities were prepared along the cement-enamel junction of extracted human premolars. Four kinds of one-bottle/one-step adhesive systems (AQ Bond Plus, G-Bond, Absolute and Clearfil Tri-S Bond), and a total etching and two step self-etching adhesives as controls, were used. After restored according to manufacturers' instructions, half of the teeth for each system was subjected to thermocycling (5°-55°C, 6, 000 times). Then, al1 of restorations were immersed in a 50%(w/v) silver nitrate solution for 24 hours, and soaked in the photo-developing solution under fluorescent light for 8 hours. The resin-dentin/enamel interfaces were observed under the FE-SEM to evaluate nanoleakage. Three systems (G-Bond, Clearfil Tri-S Bond and Clearfil MEGA BOND) did not show nanoleakage, while AQ Bond Plus, Absolute and the total etching system showed nanoleakage only from gingival margins. The thermocycling accelerated nanoleakage severely.

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The advanced medical science and supports have succeeded in prolongation of our span of life as well as improvement of quality of life. For further improvement of oral health promotion, an epidemiological survey to understand the future diversity of oral diseases is needed. The purpose of this survey was to provide information on the current state of dental treatment needs at an isolated island, Niijima-Honson. The survey was undertaken to make clear the tendency of the patients who received clinical treatments at the National Health Insurance Hospital of Niijima-Honson Dental Clinic. We investigated the data of those patients visited the dental clinic between April 2002 and March 2003, and recorded them by age, sex, pain, and chief complaint. The total number of patients during one year was 7, 872, and average daily number of patients was 34.1. The total number of new patients during one year was 1, 087, and average daily number of patients was 4.3. About 30 % of new patients had a chief complaint with some kind of pain. Especially, approximately half of twenties and thirties patients had a pain of oral hard or soft tissue. From the classification of their chief complaint, shedding of metal restoration, was the most frequent chief complaint (19.4 %), followed by primary caries and secondary caries (18.0 %), root canal treatment (13.3 %).

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