The Effect of Changes in the Angular Position of Implants on Metal Artifact Reduction in Cone-Beam Computed Tomography Images: A Scoping Review

Table 1

Chart of included studies.

Author year reference

Implant placement environment

Number of implants

Width of implants (mm)

Length of implants (mm)

Center-to-center distance between implants (mm)

Anatomical region of the implants

Material and brand of the implants

Angles (degree)

Exposure time (seconds)

Voltage (kVp)

Beam currents (mA)

Study analysis

Result

Conclusion

Min and Kim 2021 [2]

A block made of polyvinyl siloxane impression material

Two

4

10

8.5

Due to the placement of the implants in the block, no equivalent can be considered for the exact location of the implant in the jaw

Titanium (point implant)

Alpha, beta, gamma; 0; 15; 30; 45; 60; 75; 90

17

78

8

Quantitative analysis (metal artifacts were quantified using the mean and standard deviation of gray values)

With increasing alpha angle (rotation in the frontal plane), ΔGVs of group A (VOIs on the extension line of implants) and B (VOIs on the side of implants) increased, but no significant change was observed in group C (other peripheral VOIs).; The ΔGVs of group A also increased with increasing beta angle (rotation in the sagittal plane).; No significant change in ΔGVs for gamma rotation (simultaneous rotation in the frontal and sagittal planes) in all VOIs was observed

Alpha angle’s increasing can reduce inter-implant metal artifacts in CBCT images and thus tilting patient’s head is a way to reduce metal artifacts

Min and Kim 2020 [34]

Polyurethane synthetic bone

Two

4

10

8.5

Due to the placement of the implants in the bone block, no equivalent can be considered for the exact location of the implant in the jaw

Titanium (point implant)

Alpha; 0; 15; 30; 45; 60; 75; 90

17

78

8

Quantitative analysis (correlation coefficients of microstructural parameters in micro-CT and CBCT were used to quantify the effect of metal artifacts)

For VOI1 (the VOI between the implants) and VOI2 (the VOI on the extension line of the two implants), the correlation; coefficient increased with increasing alpha angle (rotation in the plane that including the longitudinal axes of the two implants) from zero to 90°. Unlike other VOIs, for VOI3 (the VOI on the side-of the extension line), the correlation coefficients gradually decreased with increasing alpha angle

Alpha angle’s changes can affect the quality of CBCT image

Luckow, et al. 2011 [33]

Lower jaw of a five-month-old pig

Two

4.1

10

Mesial and distal of the canine

Titanium (straumann AG)

Alpha, beta; 0; 5.2; 9.8; 14.5; Phi; 0; 30; 45; 90

17

70; 72; 74; 76; 78; 80 (70 to 80)

2; 7; 10 (1 to 10)

Quantitative analysis (the deviance of the detected local absorption values (gray levels) between the CBCT-data and the (SR) CT-data were used to quantify the image quality)

Tilting the pig’s mandible in the frontal plane called α angle. Increasing the α angle can improves the image quality

Moderate tilting of the porcine mandible with dental implants can reduce the artifacts in the CBCT images and improve the image quality because tilting the jaw can reduce the overlap of highly X-ray absorbing implants and hard tissues

ΔGVs: mean gray values, VOIs: volumes of interest.