the biological effects of radiation especially in the oral cavity

1. 1-apr-15 1Be Happy

2. 1-apr-15 2Be Happy

3. RADIOBIOLOGY is the study of effects of ionizing
radiation on living systems.
Initial interaction between radiation & matter occur
with in first (10—13)second after exposure.
Molecular change lead to alteration in cells &
organisms.
1-apr-15 3Be Happy

4.  Radiosensitive basal cell layer more prone
 200cGy 5 days a week exposure
 Area of redness and inflammation (1st week) .
 The irradiated mucous membrane begins to
separate from underlying connective tissue(2nd
week).
 Formation of a white to yellow pseudomembrane
 Food intake is difficult.
 Sites : palate, floor of mouth.
 Complication :Candida albicans
1-apr-15 4Be Happy

5. 1-apr-15 5Be Happy

6. 1-apr-15 6Be Happy

7.  Fate :Healing completed by two months .
 Mucous membrane become atrophic , thin, and
relatively avascular.
 complicate denture wearing because they may
cause oral ulcerations of the tissue.
 Management :
1.Topical anesthetics during meal time
2.Good oral hygiene
1-apr-15 7Be Happy

8. Doses in therapeutic range
cause extensive degeneration
of the normal histologic
architecture of taste buds.
 Loss of taste acuity (2-3 weeks)
 Bitter and acid flavours are more affected when
the posterior two third of the tongue is irradiated
and salt and sweet when the anterior two third of
the tongue is irradiated .
 Management :Taste loss is reversible and
recovery takes 60 to 120 days.
1-apr-15 8Be Happy

9.  Major salivary gland sensitive to 20-30Gy.
 Parenchymal component of the salivary glands is
radiosensitive (parotid glands> submandibular or
sublingual glands).
 Effects:1.Hyposalivation (1st week)
2.Dry mouth
3.Difficulty & painful swallowing
4.Thick & viscous saliva(!)
5.Altered pH-5.5
6.Decreased buffering capacity
7.Initiate decalcification
 Extend of reduced flow is dose dependent and
reaches 0 at 60Gy.
EARLY
1-apr-15 9Be Happy

10.  Late effects: chronic inflammatory response,
progressive fibrosis of glands, apoptosis & loss of
fine vasculature.
1-apr-15 10Be Happy

11. Management:
 Dryness of mouth usually subsides in 6-12
months because of compensatory hypertrophy of
residual salivary gland tissue.
 Salivary substitutes
 Sugar free chewing gums (xylitol)
1-apr-15 11Be Happy

12.  If exposure before calcification: destroy the tooth
bud.
 Irradiation after calcification has begun:
malformations and arresting general growth.
 Irradiated teeth with altered root forms still erupt.
 Pulpal tissue :fibroatrophy
 No effect on the enamel, dentin or cementum and
radiation does not increase their solubility
 Radiation caries: rampant caries
1-apr-15 12Be Happy

13.  Radiation caries is a rampant form of dental decay
that may occur in individuals who receive a
course of radiotherapy that includes exposure of
salivary glands.
 Etiology :changes in salivary glands and saliva,
reduced flow, decreased pH, reduced buffering
capacity, increased viscosity and altered flora .
 Greater solubility of tooth structure and reduce
remineralization.
 Three types of radiation caries exist:
1-apr-15 13Be Happy

14. 1-apr-15 14Be Happy

15. 1.WIDE SPREAD SUPERFICIAL LESIONS
INVOLVING BUCCAL,PALATAL, INCISAL &
OCCLUSAL ASPECTS
2. CEMENTUM & DENTIN IN CERVICAL
REGION
3.DARK PIGMENTATION OF ENTIRE CROWN
 Management : Daily application of a viscous
topical 1%neutral sodium fluoride gel in a
custom made applicator trays
 Restoration & good oral hygiene
 Teeth with gross caries extracted before
irradiation
NOTE!! Radiation caries is a lifelong threat.
1-apr-15 15Be Happy

16.  Bone is resistant to x-ray radiation, though
osteoblasts are sensitive.
 Decrease in general bone vitality
 Localised osteoporosis
 Inability of irradiated bone to react normally to
infection – damage of vascular bed
 Hypoxic , hypocellular & hypovasular
 Atrophic endosteum
 Normal marrow is replaced by fatty marrow &
fibrous tissue.
 Delayed healing of sockets after extraction
 Osteoradionecrosis: radiation trauma infection
1-apr-15 16Be Happy

17. 1-apr-15 17Be Happy

18.  Effects :Painful acute mucositis and dermatitis
 Depending on field of radiation, dose, age of
patient, the following outcomes are possible:
 Severe deep boring pain
 Elevated temperature
 Osteoradionecrosis
 Trismus
 Fetid breath
 Pathological fracture
 Intraoral & extraoral fistulas
 Mandible is more affected than maxilla (due to
less blood supply)
1-apr-15 18Be Happy

19.  OSTEORADIONECROSIS (ORN):Characterised
by a chronic, painful infection & necrosis
accompanied by late sequestration and
sometimes permanent deformity.
 Radiography : Moth eaten appearance of bone-
scattered areas of radiolucency with ill defined
borders.
1-apr-15 19Be Happy

20. 1-apr-15 20Be Happy

21.  Management :1. pentoxifylline and vitamin E
2. Conservative debridement to remove spicules
of bone
3. Segmental mandibulectomy and reconstruction
4.Hyper baric oxygen (HBO): O2 at high pressure
stimulate blood vessel formation.
1-apr-15 21Be Happy

22.  Inflammation & fibrosis
 Trismus in muscles of mastication
 Involved muscle: masseter, pterygoid
 Restriction in mouth opening by 2 months
 Management : physiotherapy
1-apr-15 22Be Happy

23. 1-apr-15 23Be Happy

24. 1-apr-15 Be Happy 24