There is also a greater possibility of direct (in-mouth) repair of failed veneering materials and greater shock-absorbing potential relative to occlusal force in comparison with porcelain. The trend to adhere resin materials instead of porcelain, from Brånemark and colleagues’ recommendations for acrylic resin as an occlusal surface material in the early 1980s, also cannot be ignored. All metal crowns were used about 10.3% of the time in molar regions because of a lack of strong aesthetic requirements. Zirconia, however, accounted for 14.3%; only about half of its use in the anterior region. Possible reasons include this region not being an aesthetic area and veneer material fracture and chipping problems that have yet to be completely resolved.

3. Implant overdentures (IODs) (Table 3)

Some 19% of IOD design work is left to technicians, while 80% is performed according to the instructions of, or in consultation with, dentists (Q7). As was the case with the question concerning overall prosthesis design described above, these results indicate that a team approach is being put into practice.

Bar and clip attachments were most commonly used for IODs, followed by magnet, ball, and socket, and Locator attachments (Q8) (Figure 4). It is noteworthy among the questionnaire results that magnetic attachment use is highest in Asian countries, including Japan. Additionally, it is thought that the low use of Locators (5.2%) is strongly influenced by Japan’s strict pharmaceutical regulations and because the MHLW in Japan had not yet licensed the device at the time the questionnaire was administered. Conversely, ball and socket attachments have been standardized by major implant manufacturers, and the freedom with which prefabricated parts can be used has led to their comparatively broad use. IOD use in Japan is by no means widespread; a survey of IOD use in ten countries by Carlsson et al. revealed that the adoption rate of these devices in Japan was just 7% for individuals with mandibular edentulism.