The Ultimate aim or goal of dentistry should be stated as “to contribute to the general health promotion by preserving healthy teeth in our mouth”. Japanese “8020” movement is well-known in the world, because to preserve 20 teeth in each 80 years old individual is an excellent and understandable target to pursue in general populations all over the world. However, the 8020 is still an unachievable target in Japan.
Based on a recent government survey, the fact in 1997 is not 8020 but 8005 in Japan. Why is there so much difference between the slogan of the movement and the result? There might be several reasons the most relevant are: 1) problems in dental philosophy, 2) problems in dental education, and 3) problems in dental administration. First, the problems in dental philosophy is “over reliance on treatment skill or technics.” Since dentistry is a part of medicine, the dental disorders, even caries and periodontitis, should be managed by causal therapies. However, we dentists usually treat the results of the disorder such as defect and missing teeth easily, by using dental artificial materials every day. The problem is that we could ground excessive dental organ (Enamel and dentine) to restore or make a rehabilitation without scientific consideration on the side effect which could be induced by the procedure. The absence of the spirits to fight against the cause of the disease seriously in due to problems in dental education. In Japan, the aim of the dental education system has been to make dentists who could treat patients just after graduation from the dental school. To make a lot of dentists who are well in symptomatic treatment even just after their graduation, undergraduate education in dentistry focused on treatment methodology without focusing on the cause of dental diseases. Finally, problems in the administration of medical and dental insurance further continue to discourage them to do prevention against dental diseases, because financial support for prevention is poorer than support for dental restorations in Japan. On the other hand, medical concepts are gradually moving to evidence-based practice and patient centered care. I am also applying these concepts to our clinics and under and post graduate education. Surprisingly, the concepts fit very even in the restorative dentistry. It is the time to change, with Adhesive dentistry is not just a little adjustment to the future direction but a high possibility to contribute to the future dentistry.

View full abstract

The efficacy of 4-methacryloyloxy phthalic acid (4-MPA) as a component of self-etching primer was investigated. First 4-MPA was dissolved into ethanol, 35% ethanol aqueous solution, dimethyl sulfoxide (DMSO), 35% DMSO aqueous solution, or 35% HEMA aqueous solution, and then each primer was applied to the polished dentin. The tensile bond strength was measured after 1 day immersion in 37°Cwater. The aqueous solution gave higher bond strength, and 35% HEMA solution gave the highest bond strength.

View full abstract

Recently, several adhesive systems which include a self-etching primer were developed to simplify the bonding protocol and improve the bond strength of light-cured composite resin. In this study, we evaluate the effect of the experimental self-etching primer containing 2-acryloyloxyethyl hydrogen maleate (2AEM) on bonding of lightcured composite resin to polished enamel and dentin.
Although the experimental self-etching primer significantly enhanced bonding of light -cured composite resin to polished enamel and dentin (p<0.05), its efficacy was varied with concentration of monomer and bonding agents. For dentin, the bond strength ranged from 15.4?±2.8 to 21.4±3.9 MPa; PB, from 6.5±2.9 to 12.0±2.3 MPa; MP. However, when treated dentin was rinsed with water, the efficacy of self-etching primer reduced respectively. For the enamel, the bond strength ranged from 13.5±3.1 to 22.7±3.0 MPa; PB, from 13.4±4.0 to 21.4±4.0 MPa; MP, and they did not reduce after rinsing with water. These results indicate that the experimental self-etching primer significantly improve the bond strength of light-cured composite resin to polished enamel and dentin.

View full abstract

In this study, I investigated the wound healing process of exposed pulp which showed good histopathological prognosis after direct capping with adhesive resins.
When direct capping of adhesive resins was conducted under clinically appropriate conditions, the pulp was safely protected and showed that histopathological restorative change would begin.
Histopathologically, the wound healing process was observed in the following order: disappearence of pulp inflammation, collagen fiber matrix formation, calcification of the matrix, and dentin bridge formation.
These processes usually began at the peripheral corner of the exposed pulp and then developed to the center portion. But sometimes small points or island-like restorative spots were scattered separately on the surface of the exposed pulp and wound healing was accomplished by mutual connection of these spots to each other and they extended to complete the dentin bridge formation over time.

View full abstract

In conventional prosthodontic treatment, large quantity of tooth reduction is necessary to achieve sufficient retention for fixed prostheses. However, abutment teeth surface remained enamel posseses higher prevention capability for extensive caries and block the penetration of bacterial production to dental pulp. The conservation of tooth substrate, especially enamel is considered to be essential for the elongation of life piriods of restored teeth. In the prosthodontic treatment with intact teeth, application of adhesion-fixed prostheses which could minimize amount of loss of tissues is desirable.In this article, the effective method for conservation of tooth substrate in the case of fixed partial denture with intact abutment teeth was discussed and conservation of abutment tooth substrate in the treatment applied adhesion or adhesion-mechanically retained bridge was described. Furthermore, new fixed prosthodontic appliance, adhesion pontic bridge which does not require removal of tooth so much was discussed.

View full abstract

To determine amount of eliminated tooth substance for the cavity preparation of four crown restorations; porcelain fused metal crown (MB) and porcelain laminate veneer (PLV) on artificial upper central incisors, and MOD metal inlay (MI) and full coverage cast crown (FCC) on artificial upper second premolars were prepared. By the cavity preparations, the weight loss of the artificial teeth was determined as 52.1 vol% (MB), 14.9 vol% (PLV), 13.7 vol% (MI) and 31.3 vol% (FCC). It should be noticed that significantly large amount of crown was sacrificed for these four preparations. More effort should be made to establish more conservative cavity preparation based on a new concept to minimize an elimination of the sound enamel and dentin.

View full abstract

The purpose of this study was to clarify the relationship between the shape of secondary caries developing from the margin of cast crown and the state of enamel remaining near the margin. Ten extracted human premolar teeth were restored with cast crown. The shapes of prepared teeth were following three types. 1) The margin of cast crown and the prepared surface were set on dentine, 2) The margin and the prepared surface were set on enamel, 3) The margin was set on enamel, but the prepared surface was set on dentine. The crowns were cemented with zinc phosphate cement. In the teeth, artificial secondary caries were produced by the acid-gelatin system (pH 4.0). These specimens were sliced to serial thin sections and observed with optical microscope and microradiography. When the margin of cast crown and prepared surface were set on enamel, the development of secondary caries toward the inside of cast crown was minimal. This result leads to the conclusion that the preservation of enamel in abutment teeth is effective for prevention of secondary caries developing from the margin of cast crown.

View full abstract

Progress in adhesive dentistry has enabled crown prosthodontic techniques that minimize the removal of teeth. Adhesion to enamel, whenever possible, has advantages, and efforts should be made to form abutment teeth locaized to the enamel.
To ensure there is no overtsight in the formation of abutment teeth at the mandibular and maxillary anterior teeth, we studied in detail the thickness of enamel at the lingual side of the anterior teeth in addition to conventional studies of the thickness of the labial enamel. The following results were obtained.
1. The thickness of the enamel of maxillary and mandibular anterior teeth was 0.2 to 0.5mm at the cervical region, 0.5 to 1.2mm at the central region, and 0.9 to 1. 6mm at the incisal region on the labial surface, and 0.1mm to 0.4mm at the cervical regiom, 0.4 to 1.0mm at the central region, and 0.4mm to 1.0mm at the incisal region on the lingual surface.
2. When enamel thickness was compared between the labial surface and the lingual surface of the maxillary and mandibular anterior teeth, the lingual enamel was found to be thinner than the labial enamel.
3. From the central region to the incisal region of tooth crown, there was trend toward virtually no change in the thickness of the central region, the labial angle, and proximal surface on the labial side. On the labial surface from the central region to the incisal region, however, enamel was thicker at the lingual angel than the central lingual surface, and enamel tended to be thicker at the proximal surface that at the lingual angel.
4. As for enamel thickness on the lingual surface, the maxillary canine teeth tended to be thicker in the lingual central region, in contrast to other anterior teeth.

View full abstract

For the progress of adhesive dentistry, we can reduce tooth reduction. In this paper, we introduced Resin Direct Bond Bridge, new type porcelain jacket crown and so on.

View full abstract