Code
IT(N•cm)
RT(N•cm)
ISQ
12S
13.67 (1.88)
11.68 (1.06)
51.40 (2.95)
06D
20.19 (1.61)
17.45 (1.28)
53.77 (2.73)
06S
22.30 (1.78)
20.25 (2.47)
55.66(1.62)
Implant code
Thread type
Pitch (mm)
Lead (mm)
Lead angle (degree)
Total thread length (mm)
12S
Single-threaded
1.2
1.2
8.1
64
06D
Double-threaded
0.6
1.2
8.1
129
06S
Single-threaded
0.6
0.6
4.65
129
Figure 6. Bone debris at the contact interfaces. a Numbers of debris particles. b Number and size of debris particles. Each dot indicates a debris particle, and dashes indicate median particle sizes. Particle sizes: small, < 1000 μm2; medium, 1000–10000 μm2, and large, ≥ 10,000 μm2. c Particle size distribution
Figure 5. Microscopic analysis of contact interfaces. Microscopic observations of the artificial bone-implant and number of debris particles. The small arrows in the panel indicate voids in the implant-bone interface
Figure 4. Torque kinetics. Immediately after insertion terminated, the implant was removed using the same load and rotation speed. Torque kinetics were measured during implant insertion (top) and removal (bottom)
Figure 3. Comparison between IT and RT. Maximum IT value was measured when insertion was terminated. Immediately after insertion, the implant was removed, and the RT value was measured when removal commenced
Figure 2. Insertion torque (IT), removal torque (RT), and implant stability quotient (ISQ)
Figure 1. Implants. Implant code 12S is similar to a commercially available standard single-threaded implant with equal thread pitch and a 1.2-mm lead. The thread length of implant code 06D is doubled by adding the second thread (light blue). The thread length of implant code 06S is doubled by a 50% reduction in pitch and lead angles. Characteristics of each implant are summarized in Table 1
Fi...
References
Javed F, Ahmed HB, Crespi R, Romanos GE. Role of primary stability for successful osseointegration of dental implants: factors of influence and evaluation. Interv Med Appl Sci. 2013;5:162–7.
Falco A, Berardini M, Trisi P. Correlation between implant geometry, implant surface, insertion torque, and primary stability: in vitro biomechanical analysis. Int J Oral Maxillofac Implan...
Although bone models composed of a combination of cortical and cancellous bone are also available, this study used a single bone model with a homogeneous density to eliminate any effect of cortical bone and evaluate only the effect of design features on torque and ISQ values.
Experimental implant placement using artificial bone models is generally conducted to si...
Clinicians are advised to recognize the risk associated with using a multithreaded implant with a high lead angle, which may compromise primary stability because of greater bone tissue damage despite faster insertion. The question of placement speed warrants further consideration. Indeed, another advantage of double-threaded implants is placement speed. The implantation speed...
Moreover, the IT and RT values of 12S were consistent with those of the standard implant (Straumann) measured in our previous study. Here, the RT value of each implant was lower compared with their respective IT values, consistent with other reports. The IT and RT values of 06S were highest, followed by 06D and 12S. In contrast, the differences between RT and IT values were highest for...
In the artificial bone adjacent to 06D, there were more voids compared with those associated with 06S or 12S, which accounts for the increase in torque. The highest numbers and larger sizes of debris particles were associated with 06D, followed by 0S and 12S, indicating the potential for greater tissue damage. These results likely explain the lower (50%) torque value of 06S compared with tho...
Discussion
We show here that increasing thread length and reducing pitch can increase primary implant stability without changing the size of an implant. Compared with the standard single-threaded implant with a 1.2-mm pitch/lead (12S), torque values and ISQ were significantly increased by doubling the thread length by adding the second thread (06D) or by reducing pitch/lead and lead angle o...
Results
The IT, RT, and ISQ values revealed significant differences among the implants (Table 2).
The IT and RT values of 12S were not significantly different compared with published data (IT, 13.13 ± 1.763 N cm; RT, 12.37 ± 1.746 N cm) (Student t test, df = 9, t = 2.91, p < .017). Compared with 12S, the IT and RT values of 06D and 06S were significantly different (147% and 150%, a...
Methods
Implants
Three types of grade-4 titanium cylindrical nonself-tapping implants (codes 12S, 06D, and 06S) were specially designed and manufactured (Suwa Co., Ltd., Fujiyoshida, Yamanashi, Japan) (Fig. 1 and Table 1). The code 12S single-threaded implant served as a reference. Codes 06D and 06S were designed to double the thread length compared to 12S. Code 06D was a double-threated impla...
Introduction
Secure primary stability is positively associated with successful long-term implant integration to ensure a successful clinical outcome. Initial implant stability is defined as biomechanical stability upon insertion, which is influenced by factors such as bone quantity and quality, geometry of the implant, surgical technique, and insertion torque (IT). New bone develops around the ...
Effects of implant thread design on primary stability—a comparison between single- and double-threaded implants in an artificial bone model
Abstract
Background
Primary implant stability is essential for osseointegration. To increase stability without changing the implant size, the thread length must be extended by reducing pitch, using a double-threaded implant, or reducing pitch/lead a...
Figure 6. Bone debris at the contact interfaces. a Numbers of debris particles. b Number and size of debris particles. Each dot indicates a debris particle, and dashes indicate median particle sizes. Particle sizes: small, < 1000 μm2; medium, 1000–10000 μm2, and large, ≥ 10,000 μm2. c Particle size distribution
Figure 5. Microscopic analysis of contact interfaces. Microscopic observations of the artificial bone-implant and number of debris particles. The small arrows in the panel indicate voids in the implant-bone interface
Figure 4. Torque kinetics. Immediately after insertion terminated, the implant was removed using the same load and rotation speed. Torque kinetics were measured during implant insertion (top) and removal (bottom)
Figure 2. Insertion torque (IT), removal torque (RT), and implant stability quotient (ISQ)
Table 2. Implants. Implant code 12S is similar to a commercially available standard single-threaded implant with equal thread pitch and a 1.2-mm lead. The thread length of implant code 06D is doubled by adding the second thread (light blue). The thread length of implant code 06S is doubled by a 50% reduction in pitch and lead angles. Characteristics of each implant are summarized in Table 1....
Code
IT(N•cm)
RT(N•cm)
ISQ
12S
13.67 (1.88)
11.68 (1.06)
51.40 (2.95)
06D
20.19 (1.61)
17.45 (1.28)
53.77 (2.73)
06S
22.30 (1.78)
20.25 (2.47)
55.66(1.62)
Implant code
Thread type
Pitch (mm)
Lead (mm)
Lead angle (degree)
Total thread length (mm)
12S
Single-threaded
1.2
1.2
8.1
64
06D
Double-threaded
0.6
1.2
8.1
129
06S
Single-threaded
0.6
0.6
4.65
129
The question of placement speed warrants further consideration. Indeed, another advantage of double-threaded implants is placement speed. The implantation speed of 06D was twice that of 06S, and implantation was completed twice as fast. Nevertheless, while plastic bottles and emergency valves have double-threaded screws for faster opening and closing, the effect...
Here, the RT value of each implant was lower compared with their respective IT values, consistent with other reports. The IT and RT values of 06S were highest, followed by 06D and 12S. In contrast, the differences between RT and IT values were highest for 12S, followed by 06D, and in 06S. We reported that the RT decreased more than IT. Thus, 06S had the lowest rate of decline (IT...
In the artificial bone adjacent to 06D, there were more voids compared with those associated with 06S or 12S, which accounts for the increase in torque. The highest numbers and larger sizes of debris particles were associated with 06D, followed by 0S and 12S, indicating the potential for greater tissue damage. These results likely explain the lower (50%) torque value of 06S compared wi...
In the artificial bone adjacent to 06D, there were more voids compared with those associated with 06S or 12S, which accounts for the increase in torque. The highest numbers and larger sizes of debris particles were associated with 06D, followed by 0S and 12S, indicating the potential for greater tissue damage. These results likely explain the lower (50%) torque value of 06S compared wi...
Discussion
We show here that increasing thread length and reducing pitch can increase primary implant stability without changing the size of an implant. Compared with the standard single-threaded implant with a 1.2-mm pitch/lead (12S), torque values and ISQ were significantly increased by doubling the thread length by adding the second thread (06D) or by reducing pitch/lead and lead angle o...
Results
The IT, RT, and ISQ values revealed significant differences among the implants (Table 2).
The IT and RT values of 12S were not significantly different compared with published data (IT, 13.13 ± 1.763 N cm; RT, 12.37 ± 1.746 N cm) (Student t test, df = 9, t = 2.91, p < .017). Compared with 12S, the IT and RT values of 06D and 06S were significantly different (147% and 150%, a...
Implants
Three types of grade-4 titanium cylindrical nonself-tapping implants (codes 12S, 06D, and 06S) were specially designed and manufactured (Suwa Co., Ltd., Fujiyoshida, Yamanashi, Japan) (Fig. 1 and Table 1). The code 12S single-threaded implant served as a reference. Codes 06D and 06S were designed to double the thread length compared to 12S. Code 06D was a double-threated implant with t...
Unfortunately, the effects of double- or triple-threaded implants on primary stability are known for only a few procedures, such as finite element analysis. An excessive lead angle for these implants may jeopardize their ability to sustain axial load despite faster insertion. Further, when micromotion is compared among implants with different lead angles with the same thread pitch, single-threaded...
Introduction
Secure primary stability is positively associated with successful long-term implant integration to ensure a successful clinical outcome. Initial implant stability is defined as biomechanical stability upon insertion, which is influenced by factors such as bone quantity and quality, geometry of the implant, surgical technique, and insertion torque (IT). New bone develops around the ...
Abstract
Background
Primary implant stability is essential for osseointegration. To increase stability without changing the implant size, the thread length must be extended by reducing pitch, using a double-threaded implant, or reducing pitch/lead and lead angle to half that of a single-threaded implant.
Materials and methods
We tested the stabilities of these configurations using artificial...