[Restoration of four missing upper-incisors with fixed bridges. I. A survey of fifty fixed bridges].

Four missing upper-incisors are usually restored in practice by both ways, fixed bridges and removable partial dentures. A survey of fifty fixed bridges for this type of missing teeth was conducted, in order to find out some points of caution when bridges are selected. The following results were obtained: 1. The average age of patients was 47 years old and the average life span of bridges was about 10 years. 2. Six-tooth fixed bridges extending from cuspid to cuspid, that is, bridges with two abutment teeth made up 70% of all bridges. 3. Band-crowns were used in the highest frequency (50%) retainers. 4. Various kinds of disorders were detected in the gathered bridges. Particularly recurrent caries and alveolar bone loss around the abutment teeth were remarkable. 5. Three-quarter crowns became uncemented in high frequency and therefore seemed to provide inadequate retention. 6. Regarding the contact of pontic with the ridge tissue, the effect of the material used was predominant to the form. 7. The upper incisors of pontic could play the role of guidance during protrusive movements with very little occurrences of disorder. 8. The occlusal support index of under 8 indicated a high possibility of various disorders afterwards.