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. Zahn채rztliche Radiologie. Stuttgart, Thieme, 1987
X-rays - Retroalveolar – – – –
Preop planning Immediate postop control Not accurate for measurements Information on healing !!
Limits of 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 - Do not replace clinical exam : – Vertical intermaxillary space/dimension
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 : • Classification of Cawood et Howell Int J Oral Maxillofac Surg 1988;17: 232-6
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 - ÂŤ user-friendly Âť 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
= DIRECT
X-rays PSPP
Scanner Laser
= 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
â&#x20AC;&#x201C; 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 â&#x20AC;&#x201C; 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 -
3D Imaging – – – – –
Bony volume Bony structure Insertion axis Implants diameter Anatomical pitfalls (zygoma !)
– Accuracy of images – Transfer to peroperative : • 3D model • 3D splint • References ??
– …/…
3D Imaging
Surgical guides - On models
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 -