DEPARTMENT OF PERIODONTICS

1. T.HUDSON JONATHAN

2.  Introdution
 Radiographic techniques
-paralleling technique
-bisecting angle technique
 Bitewing radiography
 Occlusal radiography
 Panaromic radiography
 CBCT(Cone Beam Computed Tomography)
 Magnetic resonance imaging
 Subtraction radiography
 Xeroradiography
 Digital radiography
 Radiographic assessment of periodontal condition
 Normal radiographic features of healthy alveolar bone

3.  Radiographic appearance of periodontal diseases
-horizontal bone loss
-vertical bone loss
-furcation involvement
 Chronic periodontitis
 Aggressive periodontitisa
 Periodontal abcess
 Nectrotizing ulcerative periodontitis
 Systemic disease affecting periodontium
 Limitations of radiographs in periodontal condition
 Conclusion
 Reference

4.  X-ray is an electromagnetic wave of high energy and very
short wave length,which is able to pass through many
materials that are opaque to light.
 X-ray was discovered in 1895 by Wihelm conrad roentgen
(1845-1923) who was a professor at wuzerberg university in
germany.
 Working with a cathode ray tube in his laboratory,he
observed a fluorescent glow of crystals on a table near his
tube.

5.  The tube that roentgen was working with consisted of a glass
envelope(bulb) with positive and negative electrodes
encapsulated in it.
 The air in the tube was evacuated and when a high voltage
was applied,it produced a fluorescent glow.
 Roentgen shielded the tube with heavy black paper and
discovered a green colored fluorescent light generated by a
material located a few feet away from the tube.
 Roentgen also discovered that the ray could pass through the
tissue of humans,but not bones and metal objects.

6. Intra oral
- Paralleling technique
- Bisecting angle technique
Paralleling technique:
- Patient preparation:
 Prior to starting to take flims,the patient must be positioned
properly.Seat the patient and ask them to remove glasses and
any removable appliances.
 Place the lead apron and thyroid collar on the patient and adjust
the headrest to support the head while taking flims.Raise or
lower the chair to a comfortable height for the operator.

7.  The paralleling technique is accompained by placing the
receptor parallel to the long axis of the tooth.
 After this parallel relationship has been established,the
central ray must be directed perpendicular to both the tooth
and the receptor.
 Because the receptor cannot always be placed as close as
possible to the tooth due to flim holding device,image
magnification may occur.
 It is said to be superior when performed correctly as it
produce an image of linear and dimensional accuracy.To
facilitate flim placement ,the flim may be tipped up to 20
degrees.

9.  It has better dimensional accuracy as it results in less
distortion.
 The alingment of x-ray beam is simplified.
 Due to positioning instrument,it is easier to standardize
flims.
 Beacuse of paralleling instrument it is easy to align the x-ray
beam irrespective of head position.

10.  Less comfortable as the flim impinges on palate or floor of
the mouth.
 More limited due to the anatomy of the palate or floor of
mouth.
 Positioning the holder within the mouth can be difficult for
inexperienced operators.
 The apices of the teeth can sometimes appear very near to
the edge of the flim.

11.  It is an alternative to paralleling technique for taking
periapical flims.The paralleling technique is recommended for
routine periapical radiography,but there are some instances
where it is very difficult to patient anatomy or lack of co-
operation.
 In this situation the bisecting angle technique is used.The flim
can be held in the mouth with the thumb or index finger or a
bisecting instrument may be used.
 In this technique x-ray beam is directed perpendicular to an
imaginary line which bisects the angle formed by the long axis
of the tooth and flim.

13.  Because of the flim placed at angle to long axis of the
teeth,the flim doesn’t impinge on tissue as much,so it is
more comfortable.
 Flim holder is not needed ,as patient can hold the flim using
a finger.
 The flim can be angled to accomodate different anatomic
situation using this technique.

14.  Because the flim and teeth are angled to each other more
distortion will occur.
 Patient acceptance of bisecting instrument is not much
better than paralleling due to stress of finger retention.
 As there is basically no use of flim holder,it is difficult to
visualize where x-ray beam should be directed.
 Flim is less stable as the retention is done using
finger,which may cause chances of moving.

15.  Bitewing radiography is used to detect interproximal caries
and alveolar bone levels.
 The receptor is placed in the mouth parallel to the crowns of
the maxillary and mandibular posterior teeth.
 The flim is stabilized as patient is asked to bite the tab or
bitewing holder.
 The horizontal angle of the x-ray beam is then directed
through the contacts of the posterior teeth at 5-10 degree.

16.  Receptors may be positioned in horizontal or vertical
dimension with this technique,depending on the area to be
examined.
 Bitewing may be taken in anterior segment as well.In
periodontics it is prescribed to be of 4 vertical bitewing
receptors posteriorly and 3 vertical bitewing receptors
anteriorly.
 So it allows to evaluate both bone level and caries detection.

18.  Occlusal radiography is used to examine a large areas of
upper and lower jaw.The palate and floor of the mouth may
also be examined.
 It is generally taken as a supplementary radiography along
with periapical and bitewing radiograph.
 The flims are bigger than IOPA as it has to cover the
complete upper or lower jaw.It is of length 57mm and
breadth 76mm.

19.  The patient positioning is done prior to flim
placement.Patient is seated such that the sagittal plane is
perpendicular to floor and occlusal plane parallel to floor.
 The apron must be properly placed to avoid interference
with the radiographic exposure.
 use a type 4 receptor with tube side of receptor toward the
maxilla,the receptor is placed crosswise in the mouth like a
cracker.
 The central ray is directed at an angle of +65 degree and a
horizontal angulation of 0 degree.

20.  In maxilla it is used to view alveolar fractures, cyst,
supernumerary teeth,impacted canines.
 In the mandible the image field includes buccal cortical
plate,lingual cortical plate and teeth from 37-47.
 Projection of central ray is at the midline through the floor
of mouth.It is approximately 3cm below the chin at 90
degree to the receptor.
 The patient is placed tilted,that the occlusal plane is 45°
above horizontal plane.Type 4 receptor is used with the tube
of the receptor towards mandible.

22.  Salivary stones in the duct of submandibular gland.
 To evaluate the extent of lesions.
 Boundaries of maxillary sinus.
 Fracture of maxilla and mandible.
 Foreign bodies in maxilla and mandible.
 To examine cleft palate.
 Retained roots,supernumerary teeth,unerupted or impacted.

23.  Panaromic radiography or pantomography is a extra oral
radiographic technique for producing a single tomographic
image of the facial structures.
 It includes both maxillary and mandibular dental arches and
their supporting structures in a single large flim.
 It is a curvilinear variant of conventional tomography,and is
based on the principle of reciprocal movement of an x-ray
source and an image receptor around a central point or
plane called the image layer in which the object of interest is
located.

24. Patient positioning:
 Remove all removable appliance,metallic objects, necklace,
ear rings.Tongue and lip rings should also be removed if at
all possible.
 Explain the procedure to the patient and make him/her to
wear a lead apron without thyroid collar.
 The purpose of lead apron is to reduce the somatic
exposure of radiosensitive tissues and minimize genetic
exposure to the reproductive organs.
 The most radiosensitive regions of head and neck are
thyroid and salivary glands.

25.  The mid sagittal plane is positioned perpendicular to right
angle to floor and centered right to left.
 The plane of occlusion is positioned parallel to the floor.The
frankfort plane,tragal-canthus plane and ala-tragus are
used to align the vertical position of the head.
 Anteroposterior plane is aligned with specific landmark that
varies among panaromic machines.It is aligned between
maxillary lateral and canine contact.

26.  It is a technique of producing tomographic image by
sectioning of the parts and simultaneous movement of x-ray
tube head and flim cassette in opposite direction to produce
the depth of the tissue.
 In the image the anterior part appears narrower than the
posterior,so some patients seems to not match with it.
 Correct patient positioning is essential for optimal
results.Image distortion occurs,when structures are
anteriorly positioned which causes narrowing and when
posteriorly positioned causes widening of image.

28.  For initial examination of new patients in all age groups that
can provide required insight or idea in determining the need
for other projections and general screening.
 In TMJ disturbances caused by malocclusion.
 In patients suffering from pain of unknown origin.
 In patients who are unable to open the mouth,with limited
mouth opening,cannot tolerate intraoral radiography or
patients suffering from severe gagging.

29.  To eliminate the presence of any underlying disease before
complete or partial dentures are constructed.
 Suspected bony swelling or known large lesions and in cases
of mandibular asymmetry.
 In patients with history of trauma to confirm or rule out the
possibility of fractures,especially mandible.
 Before and after surgical intervention of lesions.

30.  It is the most significant technological advancement in
maxillofacial imaging.It is a form of x-ray computed
tomography in which x-rays are divergent forming a cone.
 In this the 3D visualization of manifested disease or
deformation gives diagnostic accuracy,which enables better
understanding for planning of treatment.
 There are some technological factors that made it possible
-The development of compact high quality flat panel detector
arrays.
-Reduction in the cost of computers capable of reconstruction

31. -Development of inexpensive x-ray tube capable of
continuous exposure.
-Limited volume scanning.
 Specific application in dentistry CBCT technology has a
substantial impact on maxillofacial imaging.
 It is not a replacement of panaromic or other radiographs
but it should be considered as a complimentary for specific
application.

32. Patient selection:
 There should be justification of the exposure to the patient,
so that the total diagnostic benefits are greater than the
individual determining the radiation may cause.
 Should be used only when a periapical or panaromic cannot
provide necessary information for patient diagnosis and
treatment planning.
 Cone beam computed tomography,should not be repeated
routinely on a patient without a new risk/benefit
assessment.

34.  The more important of CBCT is of planning of dental implant
placement which gives clear detail of that region.
 Ability to visualize the site of implant in the
mesiodistal,faciolingual and superio-inferior dimensions.
 It has ability to allow reliable,accurate measurements.
 Capacity to evaluate trabecular bone dentisty and cortical
thickness.
 Ability to determine axial orientation of the implant
 Gives cross sectional image of alveolar bone height,
width,angulation and accuracy depicts vital structures such
as IAN canal,sinus in maxilla.

35.  Image accuracy
 Rapid scanning time
 Multiplanar reformating
 Better images with good spatial resolution
 Economical,comfortable and safe
 Soft tissue assessment
 Assessing bone density

36.  Magnetic resonance imaging was described by paul
lauterbur in 1973 and peter mansfield further developed use
of the magnetic field and developed for clinical use around
1980.
 To make a magnetic resonance image ,the patient is placed
inside a large magnet.This magnetic field causes the nuclei
of many atoms in the body,particularly hydrogen to align
with the magnetic field.
 The scanner then directs a radiofrequency pulse into the
patient,causing some hydrogen nuclei to absorb energy.

37.  When the RF pulse is turned off,the stored enery is released
from the body and detected as a signal in a coil in the
scanner.
 This signal is used to construct the magnetic resonance
image,in essence a map of the distribution of hydrogen.
 It has an advantage of being non-invasive using non-
ionizing radiation and making high quality images of soft
tissues resolution in any imaging plane.

38.  Because of its excellent soft tissue contrast resolution,MRI is
useful for instance, the position and integrity of the disk in
the condyle, for soft tissue disease especially neoplasia
involving soft tissue such as tongue,cheek,salivary glands
and neck determining malignant involvement of lymp nodes
and determing perineural invasion of malignant neoplasia.
 Disadvantage include its high cost,long scan times and the
fact that the various metals in the imaging field either will
distort the image or may move in the strong magnetic field
injuring the patient.

40.  It is a method of imaging which uses the xeroradiographic
coping process to record images produced by diagnostic x-
rays.
 It is a method of x-ray imaging in which a visible
electrostatic pattern is produced on the surface of a
photoconductor.
 The xeroradiographic plate is made up of a 9 ½ to 14 inche
sheet of aluminium,a thin layer of vitreous or amorphous
selenium photoconductor,an interface layer,and an over
cutting on the thin selenium layer.

41.  The XR plate is charged to high positive potential by
corotron.It is then placed in a cassette and used in a manner
similar to that with conventional flim in its cassette.
 A positive XR refers to image that is blue and white with
blue representing dense areas.
 A negative XR refers to image that is blue and white but that
has been reversed so that represents the dense areas.

42. Application:
 The radiography has found application in soft tissue
imaging:in radiographic examination of the mammary
glands,muscles,tendons and ligaments.
 The main advantage of xeroradiography include enhanced
visualisation of the borders between images of different
densities(edge effect),low contrast which enables
differentiation between fat,muscle and bones.

43.  Digital imaging is an method of imaging that creates an
image that can be viewed or stored on a computer.
 Digital imaging incorporates computer technology in the
capture,display,enhancement,and storage of direct
radiographic images.
 Digital image offers some distinct advantages over film,but
like any emerging technology,it presents new and different
challenges for the practioner to overcome.

44. Advantages:
 All the procedures can be visualised almost immediately.
 Any area of the picture can be enlarged .
 Provides necessary magnification.
 Good resolution.
 Conventional developing is not necessary.
 Bone pattern,its height and depth during implant placement
can be visualised.

45.  Most assessment of progressive alveolar bone loss in clinical
practice today is achieved by interpretation ie visual
comparision of radiographs taken over time.
 Unfortunately it is difficult to detect small changes that
occur between examinations using interpretation because
the radiograph contains a superimposed background of the
teeth,cortical bone and trabecular bone.
 Digital subtraction radiography was introduced to dentistry
in 1980’s.This technique is used to detect small changes in
hard tissue that occur between examinations.

46.  In brief,digital subtraction radiography uses specialized
computer program to remove all structures that have not
changed from a set of two x-ray flims taken at different
examinations.
 This image processing procedure subtracts unchanging
teeth,cortical bone and trabecular pattern leaving only the
bone gain or loss standing out against a neutral grey
background on the subtraction image.
 The area of change may be superimposed on the original
radiograph to improve the ability of the clinician to interpret
the subtraction image.

47.  Additional software can determine the size,mass or density
of the region of change.These technique have been shown
to be more than 90./.sensitive and specific in determining
small bony changes.
 More recently this quantitative method has been shown to
co-relate highly with technique used to measure bone mass
in medicine.

48. Pre-operative Post-operative

49.  Radiographs are especially helpful in the evaluation of the
following features.
 Amount of bone present.
 Condition of alveolar crest.
 Bone loss in the furcation area.
 Width of periodontal ligament space.
 Local irritating factors that increase the risk of periodontal
disease.
-calculus
-poorly contoured or over extended restoration

50.  Root length and morphology and the crown to root ratio.
 Open interproximal contacts which may be sites for food
impaction.
 Anatomic considerations.
-Position of maxillary sinus in relation to periodontal
deformity.
-Missing,supernumerary,Impacted and tipped.
 Pathologic considerations.
-Caries,periapical lesion,root resorption.

51.  Presence of thin evenly pointed margins in the interdental
crestal bone in the anterior region.Anteriorly ,cortication at
the top of the crest may not always be evident due to the
small amount of bone present between the teeth.
 Presence of thin,smooth,evenly corticated margins in the
interdental crestal bone in the posterior region.
 Interdental crestal bone is continuous with the lamina dura
of the adjacent teeth,and the junction of the two forms a
sharp angle.
 Loss of clarity or unsharpness of this angle may be an
indication of periodontal involement.
 Thin even width of periodontal ligament space.

52.  The direction of the bone loss or bone destruction is
determined using the CEJ as the plane of reference.The bone
destruction can be in the form of
 Horizontal bone loss:when the bone loss occurs on a plane
that is parallel to a line drawn from the CEJ of a tooth to that
of an adjacent tooth,it is called horizontal bone loss.
 Vertical bone loss:when there is greater degree of bone loss
on the proximal aspect of one tooth than on the adjacent
tooth,the bone level is angular or not parallel to a line
joining CEJ.This type of bone loss is said to be vertical or
angular bone loss.

53. Furcation involvement:
 Extension of periodontal pocket between
the roots of multi-rooted tooth is called
furcation involvement.
 Radiographs can be helpful in locating
furcation involvement, however the
furcation involvement cannot be seen
unless the bone resorption extends
apically beyond furcation.

54.  It shows loss of corticated interdental crestal
margin,the bone edges become irregular are
blunted.
 Widening of PDL space at the crestal margin.
 Loss of normally sharp angle between
crestal bone and lamina dura.
 Localised or generalised bone loss of
alveolar bone.
 Loss of bone in furcation area of multi
rooted tooth.

55.  In first molar region,radiographs shows
localised deep pockets and vertical bone
resorption that often is bilateral and symmetric.
 An arch shaped loss of alveolar bone extending
from distal surface of second pre molar to the
mesial surface of second molar is also
seen.Similar involvement is apparently around
the anterior teeth.
 There is usually a distolabial migration of the
maxillary incisors with diastema formation.
 Clinically the patients are healthy except for
periodontal disease and there is no association
with any systemic disease.

56.  A periodontal abscess often arises in a pre-existing
periodontal lesion which is usually precipitated by alteration
in the subgingival flora,host resistance or both.
 This is an acute exacerbation of a process occuring in a
chronic periodontal pocket ,which may result from partial or
complete occlusion of the orifice of the pocket,furcation
involvement or diabetes.
 Radiographically,underlying bone changes may be
indistinguishable from other forms of periodontal bone
destruction.
 In an acute periodontal abscess there is no visible
radiographic findings,and this is diagnosed clinically where
the signs of acute inflammation and infection are evident.

57.  Occurrence of an abscess in the buccal and
lingual aspect shows a crater like
radiolucency,which will make the root clearer
in the affected area.
 In lateral periodontal abscess,it appears as a
localised area of increased radiolucency with
poorly defined margins.
 In the apical variety usually as a sequela of
vertical bone loss,it appears as an area of
increased radiolucency with hazy borders.

58.  Necrotizing ulcerative periodontitis is similar to that of
necrotizing ulcerative gingivitis,but it also shows loss of
clinical attachment and alveolar bone.
 This destructive form of periodontitis may arise within the
zone of pre-existing periodontitis or it may present a
sequelae of single or multiple episodes of necrotizing
ulcerative gingivitis.
 Patients affected are often younger than most patients
affected with chronic periodontitis and often show
immunosuppression and malnutrition.

59.  Systemic disease like hyperthyroidism,scleroderma,diabetes
mellitus and esinophilic granules may show,refraction of
bone and absence of lamina dura,which can mimic the
appearance of periodontal disease.
 In scleroderma there is generalised widening of the
periodontal ligament space.
 patient who are HIV positive and immunocompromised can
present with distinct form of necrotizing gingivitis and
periodontitis.

60.  Radiography provides no direct evidence of the soft tissue
involvement in gingivitis.
 However in severe cases of acute ulcerative gingivitis,where
there have been extensive craters of the interdental
papilla,inflammatory destruction of underlying crestal bone
may be observed.

61.  Radiograph provides a restricted two dimensional
representation of the three dimensional anatomic structures.
 The changes that occur in the soft tissue cannot be
preceived.They do not provide information about the health
of soft tissues,presence of mucogingival defects or the
position of the gingival marigin.
 The very earliest sign of periodontal disease cannot be
detected radiographically,however this is possible by clinical
examination.
 It is difficult to recognize any existing bony defects that are
overlapped by existing bony walls on the resultant
radiograph.

62.  Periodontium can be considered healthy,when periodontal
tissue exhibits no evidence of disease.
 Unfortunately this cannot be ascertained from radiographs
alone.Dental radiographs must be used in conjugation with
clinical examination to establish the existing condition.
 Clinical examination provides information about the soft
tissue and radiographs permit evaluation of the hard
tissues.

63. 1. Text book of oral radiology-white and paroah.
2. Carranza clinical periodontology-12th edition.
3. Oral and maxillofacial radiology-kamal G pillai.
4. Fundamental of periodontics-2nd edition Thomas
G,Wilson,Kenneth S.Kornman.
5. Periodontics revisited-Shalu Bathla.
6. Periodontology 2000 vol-73, 2017.

64. THANK YOU