1. RADIOGRAPHIC INTERPRETATION IN PERIODONTAL DIAGNOSIS

2. yyy Wilhelm Conrad Roentgen (March 27, 1845 – February 10, 1923)
Discovered X rays on Nov 8, 1895.

3. TERMINOLOGIES
RADIOPACITY: dense objects (strong absorbers)cause the radiographic image to be light.
RADIOLUCENCY: low dense objects allows the photons to pass through and cast dark area

4. POINTS TO PONDER…..
Radiograph an adjunct to clinical examination and not a substitute.
Shows the post cellular effect on bone & not the current cellular activity.

5. SUPPORTING STUCTURES OF TEETH
Gingiva
Alveolar bone
Periodontal ligament
STRUCTURES UNIQUE TO JAW

6. ALVEOLAR BONE Bone that extends between the teeth.
Lined by outer thin cortical plate – lamina dura.
Contains inner Cancellous bone with bony trabeculae.
Interdental bone height measured from bone margin to CEJ : 1- 2 mm apical to CEJ.

7. Crest of interdental septum is normally parallel to a line drawn from the cementoenamel junction (CEJ).
Gingival margin of the alveolar bone – alveolar crest – significant in the diagnosis of periodontal disease.

8. ALVEOLAR crest More tapered the tooth – more pyramidal
Anteriors – sharp and pyramidal
Wider the embrasure more flat, mesiodistally & buccolingually.
Posteriors – wide & flat

9. LAMINA DURA
Thin cortical bone anatomically represents the alveolar bone.
Highly mineralised
Thin radiopaque layer continuous around the roots & alveolar crest.

10. Thickness & density varies with occlusal stress.
Wider & more dense – tooth in heavy occlusion.
Thinner & less dense – impacted & tooth not in occlusion

11. PDL SPACE Represents periodontal ligament area
Radiolucent space between the tooth root & lamina dura
Width of PDL space varies with
Patients
Tooth
Thinnest – embedded
teeth.

12. TRABECULAR PATTERN Outer – Compact bone
Cavity - interrupted by a network of bony trabeculae (Cancellous / Spongy bone)

13. ANTERIOR MAXILLA
Thin , numerous , forming a fine granular , dense pattern & marrow spaces - SMALL & NUMEROUS

14. POSTERIOR MAXILLA
Marrow spaces larger when compared to that of anterior maxilla

15. ANTERIOR MANDIBLE Trabeculae thicker than maxilla Trabecular fewer
Oriented more horizontally
Marrow spaces larger

16. POSTERIOR MANDIBLE
Peri radicular trabeculae and marrow spaces larger than anterior mandible.
Trabecular plates arranged horizontally (STEP LADDER PATTERN).
Less no. of trabeculae below the apices

17. WOLFF'S LAW
“Number & distribution of the bony trabeculae are dependant to the strains & stresses to which the bone is subjected “

18. RADIOGRAPHIC ASSESSMENT OF PERIODONTAL CONDITION
EVALUATES
Amount of bone present
Condition of alveolar crest
Bone loss in furcation area
Width of PDL space
Local initiating factors
Calculus
Over extended restorations
Root length & morphology
Crown root ratio
Anatomical considerations
Pathological considerations
caries
Periapical lesions
Root resorption

19. RADIOLOGICAL CHANGES OF THE SUPPORTING STRUCTURES

20. ALVEOLAR BONE Changes in Interdental septa affects: Crestal bone loss
HORIZONTAL
VERTICAL
Lamina dura
Crestal density
Height and contour of bone

21. ALVEOLAR crest
Horizontal bone loss
Vertical bone loss

22. LAMINA DURA
Fuzziness / break in continuity of lamina dura.

23. PDL SPACE
Widening
Radiograph alone cannot be relied upon for the diagnosis of periodontal abscess.

24. Ankylosis – absence of PDL space

25. PERIoDONTAL DISEASES

26. CHRONIC GINGIVITIS No
No bone loss

27. Chronic PERIODONTITIS
Localized form

28. Chronic PERIODONTITIS
Generalized form

29. Chronic PERIODONTITIS
Mild Form

30. PERIODONTITIS
Moderate bone loss

31. PERIODONTITIS
Severe bone loss
Furcation involvement

32. Aggressive PERIODONTITIS

33. CONVENTIONAL RADIOGRAPHS
BITEWING
PERIAPICAL RADIOGRAPHS

34. FULL MOUTH RADIOGRAPHS
IOPA – 17/ 14 based on the film size
Bitewing - 4
FULL MOUTH RADIOGRAPHS

35. PERIAPICAL RADIOGRAPHS
TECHNIQUES
BISECTING ANGLE
PARALLELING AXIS

36. BISECTING TECHNIQUE
Western price, cleveland dentist – bisecting technique in 1904.
Also known as short cone technique.
Cieszynski’s rule of isometry.

37. ADVANTAGE DISADVANTAGE
Can be used without a film holder for anatomical problems – shallow palate, bony growths, sensitive mandibular premolar areas
Decreased exposure time
Short PID short exposure
Image distortion
Angulation problem
Unnecessary exposure of pt’s hand

38. PARALLELING TECHNIQUE
1st developed by Mc Cormic in 1920.
Also known as Fitzgerald technique, long cone technique, extended cone technique.

39. FILM POSITIONING DEVICES

40. ADVANTAGE DISADVANTAGE
Dimensional accuracy: parallel rays minimizes distortion
Standardization
Simplicity – easy to learn & use
Duplication/ repetition – accurate (serial radiographs)
Anatomical difficulties – small mouth, shallow palate
Discomfort

41. FFD -focal spot to film distance

42. BISECTING VS PARALLELING TECH
PREFERRED TECHNIQUE
LONG CONE TECHNIQUE:
More accurate
Less distortion of images

43. BITEWING Howard Riley Paper in 1925. “Interproximal radiographs”.
Horizontal bitewing
Vertical bitewing
Used for moderate to extensive bone loss

44. USES
Crestal bone level
Calculus deposits in interproximal areas
Interproximal caries
Secondary caries

45. LIMITATIONS IN CONVENTIONAL RADIOGRAPHY
2D view of 3D structure.
Lack of cross sectional information
Does not demonstrate soft tissue to hard tissue relationship.
Bone level measured from CEJ: reference point not valid.
Early destructive lesions not detectable.
Processing errors

46. IMPROVISATIONS IN CONVENTIONAL METHODS
Over come by using Caliberated Gutta Percha & Silver points – left in situ during radiographic examination.
Standardization done with intra oral grids

47. CONSTANT FILM POSITION
LOCALISING STENT
Acrylic Impression of the occlusal surfaces of the teeth on the bite block of film holder.
Rubber base impression of the occlusal surface.
A mark made on to the impressions to orient the film position
CONSTANT FILM POSITION

48. Relating the tube to positioning devices attached to film holder (Rinn system)
CONSTANT TUBE GEOMETRY

49. ORTHOPANTAMOGRAM
Single tomographic image of facial structures that includes both maxillary mandibular arches & their supporting structures.

50. Curvilinear variant of conventional tomography.
Reciprocal movement of an X ray source and image receptor around a central point or plane – “image layer”

51. ADAVANTAGES Broad coverage Low pt radiation dose
Evaluation of trauma
Location of third molars
Extensive disease
Large lesions
Tooth development
Retained teeth
Development anomalies
Low pt radiation dose
Convenience of examination of the pt
Used in pts unable to open their mouth
Short time required
Visual Aid in pt education

52. LIMITATIONS
Lacks fine anatomic details: fine structures of marginal periodontium, small carious lesion.
Overlapping structures & ghost images.
Lack of clarity of midline structures
Unequal magnification & distortion of images.
Clinically important structure – outside image layer - distorted
Resolution – poor

53. DIGITAL RADIOGRAPHS RADIOVISIOGRAPHY Sensor CCD, CMOS,BCMD, PSP
(CCD charged couple device, CMOS Complementory metal oxide semiconductor,
PSP photostimulable phosphor plates)
BCMD Bulk charged modulated device
Processing unit
Image display and analysis

54. IMAGE PROCESSING Length measurement Magnification Angle measurement
-ve image
Density measurement
Curvature measurement
Histogram

55. ADVANTAGES Speed of image capture & display Low X – ray exposure
Manipulation of image
Use of digital tools
Density measurements
Improved patient education
Ease of storage, transfer& copying

56. LIMITATIONS Smaller detection area in the sensor Patient discomfort
Hard to position
Subject to operator error.

57. DIGITAL SUBTRACTION RADIOGRAPHY
Digital subtraction radiography (DSR) was developed in the 1980.
PURPOSE:
To subtract all unchanged structures from a pair of serial films & display only the areas of change.
For periodontal films - subtraction of the teeth , cortical bone and trabecular pattern leaving only bone loss or bone gain standing out against a neutral grey back ground.

58. This process does not increase the information on the radiograph.
Aids in detection of changes in bone level not visible to the unaided eye in the original radiograph.

59. Subtracted image can also be color coded.

60. CT
Computed tomography (CT) produces an axial cross sectional image using a narrowly collimated moving beam of X-rays.
The individual elements of the CT image -voxel, a value,referred to in hounsfield units.

61. TISSUE CHARACTERIZATION
Hounsfields units
air
-1000
Water
Muscle
35-75
Trabecular bone
Cortical bone
Dentin
Enamel

62. Advantages of CT: High contrast resolution
It provides sagittal, coronal,axial view of the tissue – multiplanar reformatted imaging
Completely eliminates superimposition of images.
Tissues that differ in physical density by 1% can be distinguished.
It allows reconstruction of cross sectional images of the entire maxilla or mandible or both from a single imaging procedure.
Treatment planning for implants

63. DISADVANTAGE
Expensive
Technique sensitive
Very high density material like dental restoration produce severe artifact on CT,which makes the interpretation difficult.
Very thin contiguous or overlapping slices may result in a high dose of radiation.

64. DENTA SCAN
software program which provides computed tomographic (CT) imaging of the mandible and maxilla in three planes of reference: axial, panoramic, and oblique sagittal (or cross-sectional).
The clarity and identical scale between the various views permits - uniformity of measurements and cross-referencing of anatomic structures through all three planes.

65. Use of Dentascans
Pre-operative planning & pre-operative modelling of endosseous dental implants and subperiosteal implants.
Contour of the alveolar ridge
The height of the alveolar ridge
The location of the inferior alveolar nerve canal

66. Contd…. No. of canals PDL space, width.
Cross section of tooth at various levels

67. CONEBEAM CT
Cone beam volumetric imaging CBVI / cone beam computerised tomography CBCT.
Image acquisition process differs from the traditional CT.
Uses cone shaped beam on a two dimensional X ray sensor to scan a rotation about the patient’s head.

68. CBCT delivers an effective dose equal to a full mouth x ray series.
This is 50 to 100 times less than the radiation dose delivered during a typical CT scan.
Similar adv and disadv as CT scanning but less radiation exposure

69. APPLICATION 3 D virtual model reconstruction. Bone density measurement
Bone structures – dehiscenes, fenestrations & other periodontal defects
Implant site assesment
Impacted tooth

70. Contd… Odontogenic lesion visulalisation
Inferior alveolar nerve location
TMJ visualisation
Trauma evaluation
Paranasal sinus evaluation

71. SCINTIGRaPHY & PDL DISEASES
Bone scintigraphy is a very sensitive method for the detection of osteoblast activity of the skeleton.
The technique consists of imaging the uptake of bone-seeking radiopharmaceuticals, particularly technetium-99m labeled diphosphonates.

72. Areas of increased bone metabolism - as areas of increased radiotracer uptake, namely “hot spots.”
Decreased uptake with metabolically inactive bone, lack of osteogenesis, or an absent vascular supply – “ cold spots”

73. APPLICATIONS
Detects changes in bone which precede radiographic changes.
Active sites of active bone loss
Inflammatory and Infectious Processes: osteomyelitis, traumatic injuries,
osteoarthritis
periapical lesions
periodontal disease
Bone graft viability
Primary and metastatic malignancy
Bony pathologies

74. LIMITATIONS
Changes are not specific to a particular disease hence must be used in conjunction with clinical findings.
Expensive

75. Radiographs are adjunct to clinical evaluation.
Standardization of radiographic technique in pre & post operative treatment .
Use of accessory devices like film positioning devices, grids & GP points.
Newer imaging modalities to be used with caution

76. REFERENCES Oral radiology-white & pharaoh 5th ed
Diagnosis of dental caries, and periodontal diseases – Dental clinics of north America
Carranza-clinical periodontology-10th edition
Radiographic diagnosis in periodontal disease-journal of periodontology 2000.
Imaging methods in periodontology-perio 2004
Implant dentistry by mish
British dental journal

77. Thank you