- A commemoration of the company’s 10th anniversary -

Kiyoyuki Arikawa

After graduating from Kyushu University Faculty of Agriculture, Mr. Kiyoyuki Arikawa joined Kuraray. He has been involved in the dental materials business since joining the company, and this year marks his 38th anniversary.

Initially, he led the planning and development of products from the head office, and has won Kuraray's Merit Award for three products, including CLEARFIL™ SE Bond. In addition, since 2006, he has managed the dental materials business as General Manager of each subsidiary in Europe and the United States.

After that, he returned to Japan and served as president of Kuraray Noritake Dental from 2014 to 2020. Currently, he has handed over the president to his junior and is working as CTO.

To commemorate the 10th anniversary of Kuraray Noritake Dental Inc., I have been asked to write an article under the above title. Here in this article, I would like to write about my own impressions and some thoughts I had about the development and commercialization of various products I was directly engaged with. I was an employee of Kuraray before it was integrated with Noritake, so things described in this article will mainly be from the period during which I worked in the Dental Materials Division of Kuraray Co., Ltd. I would like to beg the readers' pardon for my failure to describe in detail Noritake Dental Supply’s products, which originated from that company’s brilliant history in the development and manufacture of dental materials.

PANAVIA™ - A PRODUCT DEVELOPED TO BECOME AN OUTSTANDING BRAND IN THE RESIN CEMENT MARKET

In August 1984, I was assigned to Kuraray’s Dental Materials Division. On that day, when I first came to the office, a celebration was being held in commemoration of PANAVIA™ EX, a dental resin cement released the previous year that had just received the President’s Prize. PANAVIA™ EX was launched with thorough preparation, as a genuine adhesive resin cement, after the company had completed the expansion of the CLEARFIL™ lineup (F, FII, Core, SC and Posterior) that it had begun designing in 1978. PANAVIA™ EX's characteristics, which enable the application of adhesive bridge technique (thanks to its strong adhesion to enamel), were particularly acclaimed by many users around the world, making it a smash-hit product.

Parallel with that great success, we focused on discovering the cause of pulpal stimulation, a problem that sometimes occurred when PANAVIA™ was applied to dentine for luting restorations, and we sought measures to prevent this problem. At first, PANAVIA™ was released with a recommendation to condition the dentine with phosphoric acid in order to increase the strength of its bond to the dentine. However, its highly-hydrophobic paste composition seemed to prevent the MDP monomer from delivering a sufficiently strong bond to dentine. In addition, it appears that the phosphoric acid treatment opened the dentinal tubules, leading to the occurrence of pulpal stimulation. We performed fact-finding surveys and held many conferences with university researchers to resolve this problem of pulpal stimulation. Among the temporary measures we made to prevent the occurrence of pulpal stimulation without changing the existing specifications of the product, we decided to recommend against conditioning the dentine with phosphoric acid, at least in Japan. With the health insurance reimbursement system supplying a good tailwind for PANAVIA™, the common understanding sprang up spontaneously in the dental materials market: "Cases requiring strong adhesion, such as adhesion bridges, should be cemented with PANAVIA™ and those which can be treated with general luting should be cemented with glass ionomer cements."

Since then, five improved versions of PANAVIA™ have been put on the market, to sweep the resin cement markets overseas as well as in Japan. The improvements were made mainly for the purposes of increasing the range of crown restorative materials -- for example to include precious metals and ceramics -- that can be treated with this product, and in order to improve handling ease in the clinical setting. Here, I would like to emphasize that what lay behind our endeavor to improve PANAVIA™ was "realizing a reliable general luting material". In pursuit of this goal, we focused on improving the product by causing the resin cement to make a strong bond to dentine through chemical polymerization. I think that those efforts of ours indeed contributed to the evolution of the PANAVIA™ brand.

The efforts we have made since the launch of PANAVIA™ back there in 1983 have now come to fruition as PANAVIA™ V5, PANAVIA™ SA Cement Universal and, most recently, PANAVIA™ Veneer LC, a light-curing veneer cement with an extra-long working time. When we talk about its PANAVIA™, there is no avoiding mentioning the technologies behind those products, in particular, the development of the indispensable catalyst technology that was incorporated into them. Our catalyst technology is an excellent one that can also be applied to other products, and every day at our Niigata Development Department, R&D activities are still being carried out to improve it further.

Owing to our efforts, these days no complaints are ever heard about pulpal stimulation caused by PANAVIA™. On the other hand, in parallel with developments involving PANAVIA™, glass ionomer cements that have also evolved. These are also widely used and strongly supported by many users around the world.

Providing the characteristics glass ionomer users want is one of the directions we have followed, which has continued since the development of PANAVIA™.

• 8 nov. 2022