Abstract
Amalgam has come into wide use as a filling material for primary molars. Recently, however, the mercury content of amalgam has given rise to a variety of problems. At the same time, composite resin is considered by many to be unsuitable for filling molars because of important questions raised concerning its resistance to abrasion due to masticatory stress or other external forces, as well as concerning its edge strength.
The newly developed K-G composite resin for molar fillings (TMM-Si3N4: Kanebo) has a completely different composition than the Bis-GMA composite resin that has been in use to date. K-G composite resin has a mechanical strength and adhesive qualities comparable to those of amalgam.
To test the use of K-G composite resin as a m o lar filler, we treated 70 patients at the Pedodontics Clinic of Nippon Dental University Hospital. A total of 105deciduous molars were filled with K-G composite resin and clinical examinations of the filling material were made during the 2-5 months that followed. The following findings were obtained:
1) Complications developed in 22 out of the 105 teeth filled (21.0%).
2) Seventeen of those cases (16.0% of total) involved complications with the filling material, primarily accounted for by marginal fractures, body fractu res or loss of fillings.
3) Abrasion of the filling material was found in only one case out of 16 class-I simple cavities. No cases of abrasion were found amound the class-I co mplex cavities or the class-II cavities treated.
4) They were no cases of spacing between the filling material and the dentine or of discoloration.
5) Complications in the tooth substance were found in six cases (5.7%). Nearly all of these were recurrent cavities.
6) Complications involving the pulp or gingiva were found in 4 cases (3.8%). All of these were class-II cavities.
Based on these findings, K-G composite resin appears to make up for the deficiencies of amalgam and thus has high clinical value as a filling material for primary molars. There is still room, however, for additional research concerning the anatomical characteristics of primary molars and physiological attrition. Therefore, we intend to continue our investigations.
