An approach in quantification of the alveolar bone changes
related to dental implant placement based on 3-D CBCT images
Xiaoli Cheng, Lifong Zou, Alessia D'Onofrio, Nikos Mardas, Nikolaos Donos;
Bart’s and The London School of Medicine and Dentistry, QMUL, UK
Introduction
Methods
•
OnDemand3D (OnDemand3D Technology Inc, US) software package
was evaluated and used for image reconstruction, analysis and
measurements of the bone thickness and height changes around the
implant. The CBCT (Vatech PaX-Reve3D) images of a dry mandible
with a implant (Straumann Standard Plus, Ø3.3 mm diameter, L12 mm)
in the distal socket of lower left 6 were taken on four different settings,
of which were low(0.20 mm) / high(0.12mm) resolution; with standard
(STD) setting / with metal artefact reduction (MAR) setting. The
diameter of the implant was measured on three sections at 12mm,
8mm and 4mm coronal from the tip of the implant. Moreover this
established method was used on a patient case. A paired of CBCT data
sets (NewTom VG, 0.125mm resolution) were obtained from a 19-yearold female patient who received a single immediate implant placement
(NobelReplace Tapered Groovy, Ø5.0mm, L13mm) on site of lower left
5 at before and a year after implant surgery. Three measurement
sections were defined for bone thickness on lingual ( L1O1, L2O2, L3O3)
and buccal side (B1O1, B2O2, B3O3) where were at 12mm, 8mm and
4mm coronal to the tip of implant.
•
•
•
•
•
Dental implants has become one of routine treatments modality and
shows reliable long-term results.
A contemporary problem is the esthetic maintenance of tissue
levels following dental implant placements.
Bone preservation - a key factor for enhance the eventual dental
implant esthetic outcome.
Advantage or disadvantage of different operation time points in
alveolar ridge preservation is still inconclusive.
Advantage of CBCT – Lower radiation dose, Rapid scan time,
Higher image accuracy, and Chair-side 3D image display.
Disadvantage of CBCT - Metallic artifact on CBCT image influences
measurements.
Objectives
•
To establish an accurate and reproducible geometric measurement
strategy that can precisely quantify alveolar bone changes related
to the implant surgical procedure, based on CBCT images taken at
before and one year after implant placement
Measurement strategy
1. Superimposition images of two CBCT data sets taken at pre & a year post implant surgery and
obtain a comparison of the two images (Fig.1)
2. Determination of the measurement position of bone thickness and height that avoided the
influence of metal artifacts (Fig.2)
3. Establishment of a reproducible and accurate measurement strategy based on the combination of
grey shade and grey
value (Fig. 3, Fig.4)
Fig.3 Method based on grey value
4. The reproducibility
and
accuracy
were
assessed by measuring
a
standard
implant
placed in a dry mandible
with
four
CBCT
parameter settings and
each measurement was
repeated three times.
Fig.1 Superimpose primary and secondary CBCT
images
Results & Conclusion
•
Fig.2 Defining correlated measurement positions
in primary & secondary CBCT images
Fig.4 Method based on the combination of grey
shade and grey value
The method based on the combination of grey shade and
grey value produced the best reproducibility and accuracy
as shown in Fig.5 & Fig.6;
• The measurements of bone changes in thickness and
height: at buccal side ΔB1O1, ΔB2O2, ΔB3O3 were -0.84mm,
-0.08, -0.03mm; Lingual side ΔL1O1, ΔL2O2, ΔL3O3 were
-0.51mm, -0.09mm, -0.06mm respectively and height
Fig. 5 Accuracy assessment of three methods on 4 CBCT settings
changes were ΔHL: - 0.3mm & ΔHB : - 0.8mm;
Fig.6 SD of bone thickness measurements
• The measurement strategy established from this study is meaningful.
using three methods.
References: Chen ST, Beagle J, Jensen SS, Chiapasco M, Darby I: Consensus statements and recommended clinical
Acknowledgement:
The useful discussion with
procedures regarding surgical techniques. The International journal of
oral & maxillofacial implants 2009, 24 Suppl:272-278
Kovacs M, Fejerdy P, Dobo NC: Metal artefact on head and neck cone-beam CT images. Fogorvosi szemle 2008, 101(5):171-178. Dr Shakeel Shahdad