Oral imaging in oral

implantology

H. Reychler

Medical imaging

- without X-rays

- with X-rays

- principles

- radioprotection

- digitalisation

- tomography

- orthopantomogram

- CT scan

- Denta scan

- ConeBeamCT

- 3D and related devices

Principles of X-rays

-To visualise, after or during radiation, hard tissues

- no accessible to clinical exam

- no accessible otherwise

- some geometrical rules and constraints

- during radiation

- position of the patient

- enlargement of the images

- immobility of the patient

- some limits

- projection

- superimposition

- morphological details without informations on physiopathology

Ballinger PW. Merrill's Atlas of Radiographic Positions and Radiologic Procedures. St Louis, Mosby, 1986 - Goaz

PW & White SC. Oral Radiology : Principles and Interpretation. St Louis, Mosby, 1987 - Langland OE et al.

Textbook of Dental Radiology. Springfield, Ill, Thomas, 1984 - Mailland M. Techniques de radiologie dentaire.

Paris, Masson, 1987 - Manson-Hing LR. Fundamentals of Dental Radiography. Philadelphia, Lea & Febiger, 1985

- Pasler FA. Zahnärztliche Radiologie. Stuttgart, Thieme, 1987

- Retroalveolar– Preop planning

– Immediate postop control

– Not accurate for measurements

– Information on healing !!

X-rays

– Quality of bone

Classification of Lekholm & Zarb (1985).

Implants survival rates depend on bone quality :

Class I : almost exclusively compact homogenous bone

Class II : thick compact bone around dense trabecular spongious bone

Class III : thin cortical bone around dense trabecular spongious bone

Class IV : thin cortical bone around dense spongious bone

Symphyseal bone

of edentulous patient

Symphyseal +

mandibular bone

Maxillary bone

Limits of X-rays

- Do not replace clinical exam :

• Bone/interdental space on the alveolar crest

Limits of X-rays

- Do not replace clinical exam :

• Alveolar crest thickness

Limits of X-rays

Height :

- screwed prosthesis : 5 mm

- sealed prosthesis : 7,5 mm

- Bona : 12, 5 mm

- Bar : 18,5 mm

Limits of X-rays

- Do not replace clinical exam :– Vertical intermaxillary space/dimension

- Do not replace clinical exam :

• Classification of Cawood

et Howell

Int J Oral Maxillofac Surg 1988;17:

232-6

Limits of X-rays

Radioprotection

- « As Low As Reasonably Achievable » principle

- To choose the most performant technique to visualise what you want,

with the lowest radiation dosis

- Mean dosis due to dental X-rays = 0.37 mSv/year/ Belgian patient

- = « only » 10 % of total radiation dosis (3.5 mSv/year)

- « Optimisation principle » means X-rays only acceptable if not any

other diagnostic tool is possible and taking into account radiation dosis

>< image quality

http://ec.europa.eu/energy/nuclear/radioprotection/publication/136en.htm - http://www.fanc.fgov.be -

Radioprotection

Digitalisation

- To modify an analogic signal/image to a digital one

- 2 different techniques :

- direct = sensors : CCD (photoelectric effect) ou CMOS (semiconductive agents)

- indirect = phosphor plates : PSPP + laser scanning

- Advantages :

- speed

- radiation dosis lowering

- computerisation

- « user-friendly » with patient, with colleagues ..

- Disadvantages :

- cost

- some hard- and software aspects

Alcaraz M et al, Dentomaxillofac Radiol, 2009 - Wakoh M et al, Bull Tokyo Dent Coll, 2001

CCD

CMOS

PSPP

X-rays

Scanner

Laser

= DIRECT

= INDIRECT

Tomography

- Principle : image of predetermined « slice » through object

- Homothetic geometrical figures due to movements…

- Complex and speedy movements of sensor and X-rays emission source

- Thickness of the slice !

- Many slices ! (MSCT)

Bourjat P et al. Tomodensitométrie cervico-faciale. Paris, Masson, 1988 - Hendee WR. The Physical Principles

of Computed Tomography. Boston, Little, Brown, 1983 -

Orthopantomogram

- Tomography adapted to the form and shape

of dental arches and adjacent tissues

- Enlargement and deformations

- Indicated as overview, must be completed

by other techniques (retroalveolar, TeleX-ray …)

Chomenko AG. Atlas of Maxillofacial Pantomographic Interpretation. Chicago, Quintessence, 1985 - Jung T.

Panorama-Röntgenographie. Heidelberg, Hüthig, 1984 - Langland OE et al. Principles and Practice of

Panoramic Radiology. Philadelphia, Saunders, 1982

Orthopantomogram

- some devices allow for 3D imaging but

only for limited areas

CT scan

- Digitalisation

- Millimetric slice thickness

- High radiation dosis (MSCT!)

- « Windows » (hard and soft tissues)

- « 3D » diagnosis may be difficult

Denta scan

- CT scan applied to dental arches and

adjacent tissues

- Images are reconstructed !

- Same limits as CT scan ones

– Anatomical pitfalls

Cone Beam CT

- CT scan principle, but

- radiation dosis is limited (10 to 30 lower than CT scan, but = 2 OPG!)

- radiation time is short : 20 to 30 seconds !

- volumetric tomography (FOV 4x4, 8x8 or 15x15 cm)

- conic beam, no slices as for MSCT

- Not any diagnostic information on soft tissues

- Patient is seated or standing

- 2D images are reconstructed in a 3D data set using algorithm

- Images may be combined to laser optical clinical view

- Images of high resolution : voxel size in mm3

- Images may be integrated in 3D images analysis software

- Most evidence-based technique

- USA : 35 % of CBCT are indicated for implantology, Am Assoc Oral &

Maxillofac Radiol recommends it for planning dental implants

De Vos W et al, Int J Oral Maxillofac Surg, 2009 – Horner K et al, Dentomaxillofac Radiol, 2009

Cone Beam CT

- Not recommended as a routine imaging technique for all implant cases

- Accuracy of measurements : error of 3 to 8 % (0,5 on 10 mm)!

- Accuracy of measurements : error of max 4 °

- But if many in-vitro studies, very few in-vivo …..

- Quality of bone : corelated to implant stability !

- Reliability of implant placement > flapless surgery (98,4 % fit of surgical

template)

- Allows for surgical navigation, surgical guide, 3D imaging

- volumetric evaluation

- 3D planning (implant axis…)

- augmentation surgery before implanting

Nickenig H-J et al, J Cranimaxillofac Surg, 2007 - Naitoh M et al, Int J Oral Maxillofac Implants, 2009 – Rugani

P et al, Int J Comput Dent, 2009 - Song Y et al, Int J Oral Maxillofac Implants, 2009 -

…/…

Cone Beam CT

- Anatomical pitfalls :

- maxillary sinus

- mandibular canal (bifid in 65 % of patients !)

- retromolar canal (in 25 % of patients !)

- mental foramina

- mandibular incisive canal

- nasal floor

- nasopalatine canal

- cortical perforations

- (TMJ)

Dreiseidler T et al, Int J Oral Maxillofac Implants, 2009 - Leitlinie der DGZMK, DZZ, 2009 -

3D Imaging

- Do not confuse 2D images of 3D structures and real 3D images and models

- Seems tricky…but errors :

- human / application / imaging / technical / registration errors

- Reliability of implant placement > flapless surgery (98,4 % fit of surgical

template)

- In real time = navigation (tracking system) : very reliable but necessitates

hard- and software : 1,5 mm / 4°

- But is essential in implantology

- to avoid some anatomical pitfalls

- to accurately plan implantation, taking care of

- constraints and occlusal aims

- constraints and esthetic aims

- anatomical aspects (bone principally)

Parel S et al, J Oral Maxillofac Surg, 2004 – Nickenig H-J et al, J Craniomaxillofac Surg, 2007 – Chen X et al,

Int J Med Robot, 2008 – Xiaojun C et al, Comput Methods Programs Biomed, 2009 – Widmann G et al, Oral

Surg Oral Med Oral Pathol Oral Radiol Endod, 2009 -

– Bony volume

– Bony structure

– Insertion axis

– Implants diameter

– Anatomical pitfalls (zygoma !)

– Accuracy of images

– Transfer to peroperative :

• 3D model

• 3D splint

• References ??

– …/…

3D Imaging

3D Imaging

- On models

Surgical guides

Surgical guides

– Computerized

Nickenig H-J et al, J Craniomaxillofac Surg, 2007 – Ersoy AE et al, J Periodontol, 2008 -

Surgical guides

– Computerized

- flapless surgery

- accuracy : 1,5 mm / 5°

Jabero M et al, Implant Dent, 2006 - Nickenig H-J et al, J Craniomaxillofac Surg, 2007 – Ersoy AE et al, J

Periodontol, 2008 -