Looking at repair requests (i.e., complications) involving the superstructures of fixed implant prostheses (Q11) (Figure 6), facing damage and chipping accounted for more than half of all requests (54.5%). Generally speaking, there are many reports that indicate a high incidence of complications related to fixed prostheses involving abutment screw loosening, detachment of cement-retained crowns, and veneer (porcelain/composite resin) fracturing and damage. Because this question addressed repair of implant prostheses, we did not obtain information about complications that can be resolved in a chair-side setting. However, the high rate of requests for facing repairs makes it clear that veneer material chipping and similar issues are occurring at a high frequency [25-27].

Although the literature includes reports indicating a greater incidence of chipping and fractures for veneering porcelain than hardened resin [45,46] and for bridges than single crowns [26,27], this questionnaire does not shed light on the relative repair rates for porcelain and composite resin, nor the types of prostheses most likely to experience these issues. In the future, it would be worthwhile to conduct follow-up surveys on the differences among veneering materials and prostheses as well as veneer material failure trends.

Other cases requiring repair seen by technicians include facing discoloration (veneering composite resin) (17%) (Figure 7) and design changes and modification requests associated with additional implants (13.9%). Studies have pointed to issues related to degradation of materials science characteristics for veneering composites that are distinct from those associated with porcelain, including loss of glossiness because of the deterioration of the surface and discoloration, wear, and attrition due to long-term use [47]. It is interesting to note how relatively frequently repairs are performed to address these issues. It has become clear that no small number of laboratory work requests deal with these issues experienced by patients undergoing implant treatment because of changes over time in the area surrounding existing implant treatments that occasionally necessitate additional implants and superstructure design changes or modifications.