A total of 495 implants placed from January 2013 to December 2017 in 203 patients (100 males, 103 females) had an average observation period of 44.0 months in patients with an average age of 63.22±11.34 years. The average primary stability was 70.87±11.45, the average secondary stability was 78.16±7.67, the survival rate was 98.6% (488/495), the success rate was 95.4% (472/495), and the marginal bone loss (mm) was 0.092±0.32.
To analyze the cases for which follow-up was performed for more than 5 years, 258 implants placed between January 2013 and December 2015 were used as subjects of the further study. There were a total of 120 (61 males, 59 females) patients with an average observation period of 62.0 months and an average age of 63.7±11.17 years. A total of 258 implants was placed, and the anterior, premolar, and molar areas were affected in 33, 69, and 156 implants, respectively, with 182 implants in the maxilla and 76 implants in the mandible. The average primary stability was 70.57 ± 12.55, average secondary stability was 78.10 ± 8.00, survival rate was 97.3% (251/258), success rate was 94.2% (243/258), and marginal bone loss (mm) was 0.074 ± 0.26.
Of the total implants, 77 were placed without bone graft, 154 were placed simultaneous to bone graft, and 27 were placed at an average of 5.34 months after bone grafting. For implantation without bone graft (set as Group A), the average primary stability was 70.59 ± 12.57, and the average secondary stability was 78.85 ± 8.05. The survival rate was 98.7% (76/77), the success rate was 94.8% (73/77), and the average marginal bone resorption (mm) was 0.073 ± 0.26. In implantation with bone graft at the same time (set as Group B), the average primary stability was 70.57 ± 12.55, and the average secondary stability was 78.06 ± 8.0. The survival rate was 96.1% (148/154), the success rate was 92.9% (143/154), and the average marginal bone resorption (mm) was 0.074 ± 0.26. In delayed placement after bone graft (set as Group C), the average primary stability was 70.56 ± 13.20, and the average secondary stability was 77.94 ± 7.50. The survival rate was 100%, the success rate was 100%, and the marginal bone resorption (mm) was 0.000 (Table 1).
Among the bone grafts used in a total of 181 cases in Groups B and C with bone graft, guided bone regeneration was used in 72, sinus elevation in 62, ridge augmentation in 21, extraction socket preservation in 3, and bone guided regeneration and maxillary sinus grafting were used in 23 cases. At the final follow-up of 258 implants, the types of prostheses were 146 cases with multiple fixed restorations, 104 cases with single fixed restorations, 3 cases with over dentures, 3 cases with two-unit bridges, and 2 cases of failure before implant restoration.
Table 1
Survival rates, success rates, marginal bone loss, and stability of the implants
Group
|
No. of
implants
|
Survival rate
(%)
|
Success rate
(%)
|
Marginal bone loss
(mm)
|
Stability (ISQ)
|
Primary
|
Secondary
|
Total
|
258
|
97.3
|
94.2
|
0.074±0.26
|
70.57±12.55
|
78.10±8.00
|
A
|
77
|
98.7
|
94.8
|
0.073±0.26
|
70.59±12.57
|
78.85±8.05
|
B
|
154
|
96.1
|
92.9
|
0.074±0.26
|
70.57±12.55
|
78.06±8.00
|
C
|
27
|
100
|
100
|
0.000
|
70.56±13.20
|
77.94±7.50
|
1) Implant stability
The average primary stability of the implants was 70.57 ± 12.55, and the average secondary stability was 78.10 ± 8.00. Of a total of 258 implants, 52 had a primary stability less than 60, and 3 implants had a secondary stability less than 60 (Table 2). The difference in implant stability among Groups A, B, and C, which had been followed for more than 5 years, was not significant (P>0.05).
Table 2
Primary and secondary stability (ISQ) of the implants
Implant Stability
|
ISQ
|
No.
|
Mean ± SD
|
Values
|
Primary
|
70.57 ± 12.55
|
≥60
|
206
|
<60
|
52
|
Secondary
|
78.10 ± 8.00
|
≥60
|
255
|
<60
|
3
|
2) Complications
Complications occurred in 15 of 258 implants (5.8%), 2 with early complications and 13 with delayed complications. In 2 cases with initial complications, both failed, and in 13 cases with delayed complications, 5 cases with peri-implantitis failed. The types of initial complications were 1 case of osseointegration failure and 1 case of root involvement. The types of delayed complications were 8 cases of peri-implantitis and 5 cases of prosthetic complications (1 case of screw loosening, 2 cases of screw fracture, and 2 cases of food impaction). There was no statistically significant difference in the number of complications among Groups A, B, and C over more than 5 years of follow-up (P>0.05).
3) Marginal bone loss
The average amount of marginal bone loss (mm) was 0.074 ± 0.26, and the average amount of bone loss at the time of one year after functioning was 0.056 ± 0.24. In a total of 258 cases, 248 (96.1%) experienced bone loss less than 1 mm within 1 year after implantation of the prosthesis, 8 (3.1%) of 1 mm or more but less than 2 mm, and 2 cases (0.8%) of implants that failed to survive due to initial complications before prosthesis placement. The difference in the amount of marginal bone resorption among Groups A, B, and C with follow-up over 5 years was not significant (P>0.05).
4) Implant treatment outcomes according to diameter
A total of 7 implants dropped out, and 4 that were 5.0mm in diameter and 3 that were 4.5mm in diameter for each implant were excluded during function. Of the 15 implants that did not meet the success criteria, 10 were 5.0 mm in diameter, 4 were 4.5 mm in diameter, and one was 4.0 mm in diameter. The order of the average amount of marginal bone resorption by the diameter of implants at the most recent visit was 5.0mm, followed by 4.0, 3.5, and 4.5mm, and no marginal bone resorption was observed in the 5.5-mm-diameter implants (Table 3). Survival rate, success rate, and the amount of marginal bone resorption according to implant diameter were not statistically significant (P>0.05).
Table 3
Survival rate, success rate, and marginal bone loss according to fixture diameter
Diameter
(mm)
|
No. of implants
|
Survivor
rate
(%)
|
Success
rate
(%)
|
Marginal bone loss (mm)
|
Installed
|
Survived
|
Succeeded
|
1 year after placement
|
most recent follow up
|
3.5
|
22
|
22
|
22
|
100
|
100
|
0.045
|
0.067
|
4.0
|
34
|
34
|
34
|
100
|
97.1
|
0.054
|
0.070
|
4.5
|
56
|
53
|
52
|
94.6
|
92.9
|
0.047
|
0.065
|
5.0
|
145
|
141
|
135
|
97.2
|
93.1
|
0.056
|
0.074
|
5.5
|
1
|
1
|
1
|
100
|
100
|
0.000
|
0.000
|
5) Implant treatment outcomes according to length
The seven implants that were eliminated numbered 5 at 10.0mm and 1 each at 8.5mm and 13.0mm. The number of implants that did not satisfy the 5 success criteria comprised 10 at 10.0mm, 2 at 8.5mm, 2 at 11.5mm, and 1 at 13mm. The average amount of limbic bone resorption at the recent visit was highest in the 8.0mm length implants, followed by those of 10.0, 11.5, 8.5mm, and no marginal bone resorption was observed at 7.0, 10.5, and 13mm (Table 4). There was no statistically significant difference in survival rate, success rate, and the amount of marginal bone resorption according to implant length (P>0.05).
Table 4
Survival rate, success rate, and marginal bone loss according to fixture length
Length
(mm)
|
No. of implants
|
Survivor
rate
(%)
|
Success
rate
(%)
|
Marginal bone loss (mm)
|
Installed
|
Survived
|
Succeeded
|
1 year after placement
|
most recent follow up
|
7.0
|
1
|
1
|
1
|
100
|
100
|
0.000
|
0.000
|
8.0
|
1
|
1
|
1
|
100
|
100
|
0.200
|
0.250
|
8.5
|
56
|
55
|
54
|
98.2
|
96.4
|
0.047
|
0.064
|
10.0
|
158
|
153
|
148
|
96.8
|
93.7
|
0.056
|
0.074
|
10.5
|
1
|
1
|
1
|
100
|
100
|
0.000
|
0.000
|
11.5
|
34
|
34
|
32
|
100
|
94.1
|
0.048
|
0.068
|
13.0
|
7
|
6
|
6
|
85.7
|
85.7
|
0.000
|
0.000
|