Patient and implant data and characteristics are shown in Tables 1, 2, 3.

Table 1 Descriptive patient dataTable 2 Descriptive implant dataTable 3 Patient and implant-related characteristics

A total of 561 patients (307 maxillae, 254 mandibles) and 2364 implants (1324 maxillae, 1040 mandibles) were included. Maxillary cases included 156 males and 151 females, with an average age of 57.2 ± 10.4 years and an average follow-up period of 105.7 ± 44.5 months. Mandibular cases included 131 males and 123 females, with an average age of 55.1 ± 10.6 years and an average follow-up period of 108.3 ± 42.6 months.

Cumulative implant survival rate

The number of failed implants was 22 and 7 in the maxilla and mandible, respectively, and the number of patients was 11 and 6 in the maxilla and mandible, respectively. The number of implants and patients who failed within 24 months were 19 implants (0–12 months: 15 implants, 12–24 months: four implants), nine patients (0–12 months: eight patients, 12–24 months: one patient) in the maxilla and three implants (breakdown; 0–12 months: three implants, 12–24 months: 0 implants), three patients (breakdown; 0–12 months: three patients, 12–24 months: 0 patients) in the mandible. Furthermore, the number of implants that failed at ≥ 24 months and the number of patients were as follows: three implants (breakdown; 24–36 months: one implant, 168–180 months: two implants), two patients (breakdown; 24–36 months: one patient, 168–180 months: one patient) in the maxilla and four implants (breakdown; 24–36 months: one implant, 72–84 months: one implant, 132–144 months: two implants), three patients (breakdown; 24–36 months: one patient, 72–84 months: one patient, 132–144 months: one patient) in the mandible (Tables 4, 5, 6, 7).

Table 4 Survival rate and number of implants depending on the investigation interval (implant level in the maxilla)Table 5 Survival rate and number of implants depending on the investigation interval (implant level in the mandible)Table 6 Survival rate and number of implants depending on the investigation interval (patient level in the maxilla)Table 7 Survival rate and number of implants depending on the investigation interval (patient level in the mandible)

The cumulative implant survival rate over 3–17 years was 94.4% at the patient level and 97.4% at the implant level for the maxilla. For the mandible, the cumulative survival rates were 96.7% at the patient level and 98.9% at the implant level. The cumulative survival rate in the maxilla was significantly lower at the implant level than in the mandible (p < 0.05), but not significantly different at the patient level (Figs. 3 and 4).

Fig. 3

Kaplan–Meier curves in the implant level. The log-rank test showed a significant difference between the maxilla and mandible (p = 0.0320)

Fig. 4

Kaplan–Meier curves in the patient level. The log-rank test showed no significant difference between the maxilla and mandible (p = 0.42)

Patient profile of implant failure and early implant failure

The details of implant failure cases for the maxilla and mandible are presented in Tables 8 and 9.

Table 8 Implant failure case in the maxillaTable 9 Implant failure case in the mandible

The survival rate was then classified into within 24 months and after 24 months. The maxillary survival rate within 24 months was 97.1% at the patient level and 98.6% at the implant level. After 24 months, the survival rate was 99.3% at the patient level and 99.8% at the implant level (p < 0.05 and < 0.01, respectively).

The mandibular survival rate within 24 months was 98.8% at the patient level and 99.7% at the implant level. After 24 months, the survival rate was 98.8% at the patient level and 99.6% at the implant level, with no significant difference (Table 10).

Table 10 Time to implant failure

Furthermore, a comparison of the maxilla and mandible regarding implant failure within 24 months resulted in a higher risk of early failure in the maxilla (implant level, p < 0.01).

Risk factors related to survival rateImplant-related factors Implant type (Table 11)Table 11 Type of implant to survival rate

Regarding differences in survival rate according to implant type, the Nobel Speedy Groovy implant (Nobel Biocare AG, Kloten, Switzerland) had survival rates of 98.3% and 99.2% for maxillary and mandibular implants, respectively; the Bone Level Tapered implant (Straumann AG, Basel, Switzerland) had survival rates of 99.3% and 100% for maxillary and mandibular implants, respectively; the Nobel Parallel CC implant (Nobel Biocare AG, Kloten, Switzerland) had survival rates of 97.8% and 100% for maxillary and mandibular implants, respectively; and the Nobel Replace Tapered Groovy implant had survival rates of 94.7% and 100% for maxillary and mandibular implants, respectively. No significant differences were observed among the survival rates according to implant type for either the maxilla or the mandible.

Implant length (Table 12)Table 12 Implant length to survival rate

Regarding the differences in survival rate according to implant length, implants of < 10 mm in length had survival rates of 97.3% and 94.1% for maxillary and mandibular implants, respectively; implants of 10 mm ≤ , < 15 mm had survival rates of 97.8% and 100% for maxillary and mandibular implants, respectively; implants of 15 mm ≤ , < 18 mm had survival rates of 99.1% and 99.2% for maxillary and mandibular implants, respectively; and implants of 18 mm ≤ had survival rates of 98.3% and 99.3% for maxillary and mandibular implants, respectively. Implant lengths < 15 mm showed significantly higher survival rates in the mandible (p < 0.05), but no significant differences were observed in the maxilla.

Primary stability (Table 13)Table 13 Primary stability to survival rate

The survival rates according to primary stability at implantation are as follows: implants with a value of < 35 Ncm had survival rates of 99.1% and 100% for the maxilla and mandible, respectively; implants with a value of 35–50 Ncm had survival rates of 97.0% and 98.8% for maxillary and mandibular implants, respectively; and implants with a value of > 50 Ncm had survival rates of 98.7% and 99.5% for maxillary and mandibular implants, respectively. No significant differences were observed in the survival rates according to primary stability for either the maxilla or the mandible.

Angle of implant placement (Table 14)Table 14 Angle of implant placement to survival rate

The survival rates of implants placed in the axial direction were 98.6% and 99.6% for the maxilla and mandible, respectively. The survival rates of tilted implants were 98.0% and 99.0% for the maxilla and mandible, respectively. No significant difference in survival rates due to the placement angle of the implant was observed for either the maxilla or the mandible.

Patient-related factors Sex (Table 15)Table 15 Sex to survival rate

For the maxilla, male patients had survival rates of 95.5% at the patient level and 98.2% at the implant level. Female patients had rates of 97.4% at the patient level and 98.5% at the implant level.

For the mandible, male patients had survival rates of 96.2% at the patient level and 99.1% at the implant level. Female patients had survival rates of 99.2% at the patient level and 99.6% at the implant level.

No significant differences were observed for either the maxilla or the mandible.

Systemic disease (Table 16)Table 16 Systemic disease to survival rate

In this study, we investigated the survival rate of implants with diabetes mellitus [10, 11], cardiovascular disease [10, 12, 13], and osteoporosis [14], which have been reported as causes of implant failure and peri-implantitis, as the main systemic diseases.

For the maxilla, healthy participants had survival rates of 96.0% at the patient level and 97.8% at the implant level. Patients with systemic disease had survival rates of 96.9% at the patient level and 99.1% at the implant level.

For the mandible, healthy participants had survival rates of 98.1% at the patient level and 99.4% at the implant level. Patients with systemic disease had survival rates of 97.0% at the patient level and 99.3% at the implant level. No significant differences were observed for either the maxilla or the mandible.

Smoking (Table 17)Table 17 Smoking to survival rate

For both the maxilla and mandible, smokers had implant survival rates of 95.5% at the patient level and 97.9% at the implant level, whereas non-smokers had implant survival rates of 97.8% at the patient level and 99.2% at the implant level. Survival rates at the implant level were significantly lower for smokers (p = 0.0086 < 0.01).

For the maxilla, smokers had implant survival rates of 96.2% at the patient level and 97.3% at the implant level, whereas non-smokers had implant survival rates of 96.6% at the patient level and 98.9% at the implant level. Smokers had significantly lower survival rates than non-smokers at the implant level (p < 0.05).

For the mandible, smokers had implant survival rates of 94.8% at the patient level and 98.7% at the implant level, whereas non-smokers had implant survival rates of 99.4% at the patient level and 99.7% at the implant level. Smokers had significantly lower survival rates than non-smokers at the patient level (p < 0.05).

Risk factors for survival rate multivariate analysis

The risk factors influencing the survival rate are shown in Table 18. To identify the risk factors for survival rate (implant failure), logistic regression analyses were performed at both the implant and patient levels. The factor with the greatest influence on survival was the maxilla in the treatment area, with an OR of 1.98 at the patient level and 5.68 at the implant level, which was significantly different (p = 0.0034, implant level). However, smoking was not statistically significant, although the OR was 1.98 at the patient level and 2.58 at the implant level (p = 0.39, p = 0.37, respectively).

Table 18 Risk factors for survival rate multivariate analysis (odds ratio)