Survival analysis

After an average time in situ of 41.2 ± 27 months (3.4 years; range 0–96 months), 40 of the 863 implants were lost. These results indicated an in situ rate of 95.4%. One-year and five-year survival rate according to Kaplan–Meier were 95.4 and 94.4%. In patients receiving an external sinus lift an in situ rate of 95.1% and in patients with an internal sinus lift an in situ rate of 96.4% after the mean follow-up of 3.4 years was achieved. These results indicated a higher survival rate for the internal sinus lift procedure, but this difference was not statistically significant (p = 0.614, Fig. 1). The in situ rates were 100% for implants with a length <10 mm, 95.3% for implants with a length 10–13 mm, and 93.9% for implants with a length >13 mm. These differences were not statistically significant (p = 0.657). Implant survival for implant diameter <3.6 mm were 100%, for implant diameter 3.6–4.5 mm 96.0%, and for implant diameter >4.5 mm 92.2%, indicating a not statistically significant difference (p = 0.123). For patients that were available for clinical follow-up examination, the plaque index showed that 86.6% of implants had a satisfactory degree of oral hygiene (grades 0 and 1). Concerning the gingival index, 76.4% of the implants showed a gingival index grade 0, 19.7% a gingival index grade 1, and 3.8% a gingival index grade 3. A probing depth of less than 3.5 mm at all four measured sites around each implant was determined for 82.8% of the implants. The width of keratinized mucosa was <1 mm in 38.9% of the implants, between 1 and 2 mm in 37.6% of the implants, and >2 mm in 11.4% of the implants. No keratinized mucosa was found in 12.1% of the cases.

Pre- and post-treatment assessment of oral health-related quality of life

In 182 patients, pre- and post-treatment oral health-related quality of life after sinus augmentation procedure using a standardized questionnaire was evaluated. Subcategories for this evaluation were (1) functional limitations, (2) physical and psychological disabilities, and (3) complaints due to the surgical procedure.

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).