[Restoration of four missing upper-incisors with fixed bridges. II. Fabrication of fourteen fixed bridges].

In the previous study, fifty fixed bridges with four missing upper-incisors were gathered and analysed. As a result, several points of caution for restoring this type of missing teeth were obtained. In this study, the relationship of b/a ratio and marginal leakage was first investigated as a preliminary study and then fourteen fixed bridges were newly made upon these results. In addition, a follow-up study within 3.5 years was conducted. 1. Marginal leakage was closely correlative to marginal fit of crowns, that is, marginal leakage occurred at the portion of the crown margin having the thick layer of cement, and expanded to the lingual and/or distal side. 2. As b/a ratio became smaller, marginal leakage increased and especially expanded in the incisal direction. 3. Ceramometal crowns were estimated to be strong enough as retainers for restoring four missing incisors. 4. Ni-Cr alloy cast as one-piece manifested frictional fit just as with a precious alloy. 5. In the follow-up study, fracture of porcelain facing and excessive wear of occluding natural teeth were detected in one case each and gingival retraction or swelling of gingiva were perceived in three cases.