Concerning functional limitations, all posed questions showed significant better values for OHRQoL after sinus augmentation procedure than before the treatment (p < 0.001; Table 1). The total score is calculated from the sum of the respective questions with high values indicating worse OHRQoL. The maximum total score achievable in the subcategory functional limitations was 18. Median total scores in the category functional limitations were 4.64 ± 4.3 (range 0–17) before and 1.65 ± 2.4 (0–13) after the treatment, indicating a significant difference (n = 169; p < 0.001).

In the subcategory physical and psychological disabilities, all questions had significant better values after the sinus lift (p < 0.001; Table 2). The total score achievable in this category was 27. Mean total scores were 5.79 ± 6.4 (range 0–27) before and 1.94 ± 3.2 (range 0–21) after the sinus augmentation procedure, indicating a significant difference (n = 164; p < 0.001).

In the subcategory complaints due to the surgical procedure, the patients were asked to answer the items regarding the periods “pre-operative,” “post-operative,” and “recently.” Six of the 11 items (items 1, 2, 6, 8, 9, and 10) were significant worse “post-operative” compared to “pre-operative” (n = 126; p ≤ 0.03; Table 3; Fig. 3). However, comparing the periods “pre-operative” and “recently,” items 1, 3, 4, 6, 7, 8, 9, and 11 showed a significant improvement (n = 126; p ≤ 0.002). Comparison of the periods “post-operative” and “recently,” all items were significant better in the period recently (n = 126; p < 0.001). Mean total scores were 5.1 ± 5.4 (range 0–26) pre-operative, 6.9 ± 6.1 (0–31) post-operative, and 2.4 ± 3.7 (range 0–27) recently. This meant a significant difference between “pre-operative” vs. “post-operative” (n = 126; p = 0.003), “pre-operative” vs. “recently” (n = 126; p < 0.001), and “post-operative” vs. “recently” (n = 126; p < 0.001).

In edentulous patients, median total scores in the category functional limitations were 8.4 ± 4.1 before and 2.7 ± 2.4 after the treatment, indicating a significant improvement (p < 0.001; Fig. 4). In addition, patients with a distal extension situation (4.6 ± 4.0 vs. 1.7 ± 2.7; p < 0.001), an extended edentulous gap (3.9 ± 3.8 vs. 1.4 ± 1.9; p = 0.009) and a single tooth gap (1.5 ± 2.2 vs. 0.6 ± 1.3; p = 0.034) showed significant lower mean total scores after the rehabilitation compared to before the treatment. Concerning the category physical and psychological disabilities, mean total score of edentulous patients showed the most distinct improvement after the procedure (11.1 ± 8.2 vs. 3.7 ± 4.5; p < 0.001; Fig. 5). For patients with a distal extension situation (5.5 ± 5.8 vs. 1.8 ± 3.3; p < 0.001), with an extended edentulous gap (4.4 ± 4.9 vs. 1.4 ± 1.7; p = 0.007) and with a single tooth gap (3.0 ± 3.0 vs. 1.0 ± 1.2; p = 0.005), total score were significantly lower after the sinus lift.