The mean residual bone height at the treated sites was 7.02 ± 1.64 mm. Ten of the 357 implants failed during the healing period, and three implants failed during the 1-year loading period. The survival rate during the healing period of these implants was 96.4%, and cylindrical implants exhibited a survival rate of 97.2%, while conical implants exhibited a survival rate of 97.0% (P-value= 0.736, OR= 1.32, 95% CI: 0.26-6.58). When the IPL was above 3 mm, the survival rate during the healing period (94.3%) was lower (P-value= 0.029, OR= 5.80, 95%CI: 1.20-28.05). As shown in Table 2, the IPL was the key factor that affected the survival rate during the healing period. Meanwhile, perforation and grafting had no significant influence on the survival rate during the healing period.
New Bone Formation
As shown in Table 1, similar results concerning NBF during the healing period were discovered in four directions (lingual, buccal, distal, mesial), the distance and angle between the sinus floor and implant had a significant influence on NBF in the lingual (distance: P-value = 0.043, angle: P-value = 0.005), buccal (distance: P-value = 0.032, angle: P-value = 0.047), distal (distance: P-value = 0.019, angle: P-value = 0.02), and mesial (distance: P-value = 0.041, angle: P-value = 0.041) directions. Shorter distance between the sinus floor and implant corresponded with greater NBF (Figure 2-3). Furthermore, smaller angles between the implant and sinus floor, also corresponded with greater NBF.
As summarized in Tables 2 and 3, the IPL is a key factor related to NBF, IPL that did not exceed 5 mm had a significant positive influence on NBF during the healing period (NBF: IPL ≥ 3 mm: 1.74 ± 1.12 mm, IPL < 3 mm: 1.36 ± 0.61 mm, univariate analysis: P-value = 0.03, multivariate analysis: P-value = 0.026, OR= 1.15, 95% CI: 1.02-1.30). Figure 4 illustrates the relationship between IPL and NBF during the healing period. In these cases of IPL between 4 mm and 4.5 mm, the largest NBF was obtained during the healing period. Another important factor was bone substitutes, the sites at which bone substitutes were used exhibited 2.22 ± 1.13 mm of NBF during the healing period, which was relatively higher than that at non-grafting sites (1.43 ± 0.79 mm, univariate analysis: P-value = 0.001, multivariate analysis: P-value = 0.001, OR= 0.28, 95%CI: 0.13-0.57).
NBF associated with adjacent implants that were placed following TSFE (1.70 ± 0.91 mm) was greater than that at a single implant site (1.53 ± 0.98 mm, P-value = 0.478, single sites: the adjacent teeth were natural teeth or implants that were not placed with TSFE (Figure 5). Further, the NBF at perforated sites was 1.34 ± 0.91 mm, and non-perforated sites exhibited 1.62 ± 0.96 mm (P-value = 0.284). Smokers (1.68 ± 0.85 mm) did not exhibit lower NBF compared with non-smokers (1.57 ± 0.98 mm, P-value = 0.684). Meanwhile, cylindrical implants (1.68 ± 1.01 mm) did not significantly exhibited greater NBF than conical implants (1.41 ± 0.83 mm, P-value = 0.20). Wide implants resulted in similar NBF to that of narrow implants (P-value = 0.899). Table 3 summarizes results of univariate analyses, according to which the aforementioned five factors did not result in significant differences in NBF during the healing period.
Table 3 also illustrates that perforation (P-value = 0.053, OR= 1.49, 95%CI: 1.00-2.23), implant shape (P-value = 0.076, OR= 1.41, 95%CI: 0.97-2.05), and the location of the treatment sites (P-value = 0.537, OR= 0.87, 95%CI: 0.57-1.34) had no obvious influence on NBF based on the results of the multivariate analysis.
Marginal Bone Loss
As shown in Table 4, smoking and diabetes did not have a significant influence on MBL during the healing period (smoking: OR = 0.99, 95%CI: 0.92-1.07, P-value = 0.803, diabetes: OR = 1.01, 95%CI: 0.93-1.10, P-value = 0.751). Furthermore, the multivariate analysis revealed another four factors (perforation: P-value = 0.165, bone grafting: P-value = 0.77, healing method: P-value = 0.738, and implant shape: P-value = 0.264) that did not influence the MBL during the healing period.