Radiation Biology

1. BY:
ADWITI VIDUSHI
B.D.S FINAL YEAR
GUIDED BY :
DR. SHALU RAI
DR. DEEPANKAR MISRA
DR. VIKASH RANJAN
DR. MUKUL PRABHAT
DR. MANSI KHATRI

2. CONTENTS
 Rationale
 Oral Mucous Membrane
 Taste Buds
 Salivary Glands
 Teeth
 Radiation Caries
 Bone
 Musculature

3. RATIONALE
 Oral cavity is exposed to large doses of radiation when
radiation therapy is used in the treatment of oral cancer.
 Radiation therapy for malignant lesions in oral cavity
indicated when Lesion radiosensitive/advanced
/deeply invasive & cannot be approached surgically.
 Radiation treatment administered as many small doses
(fractions).
 Typically 2 Gy delivered daily for weekly exposure of 10
Gy.
 Radiotherapy course continues for 6-7 weeks until total
60-70 Gy administered.
 The complications (deterministic effects) of a course of
radiotherapy on the normal oral tissues result only from
therapeutic exposures, not from radiation levels used for
diagnostic imaging.

5. ORAL MUCOUS MEMBRANE
 MUCOSITIS- Reddening and inflammation of oral mucosa
 1st Sign of mucositis – end of second week of therapy.
 ATROPHY OF RADIOSENSITIVE BASAL LAYER
 FORMATION OF WHITE-YELLOW PSEUDOMEMBRANE
 SLOUGHING OF MUCOSA
 SECONDARY INFECTION DUE TO Candida albicans
(common complication)
 HEALING (After about two months)

6. Radiation induced mucositis is initiated by direct injury to basal
epithelial cells and the cells in the underlying tissue.DNA
strands breaks and results into cell death or injury.

7. Clinical Features
 Reddish inflamed mucosa
 Areas of white pseudo
membrane
 Areas where oral epithelium is
separated from underlying
connective tissue
 Sores in mouth, gums and
tongue
 Dysphagia
 Ulcers due to radiation
necrosis
 Complications in denture
wearing

8. WHO MUCOSITIS SCALE:
1.Soreness/ Erythema
2.Erythema,ulcers but patient is able to eat solid.
3.Ulcers, requires liquid diet.
4.Food administration is not possible orally.

9. Management
 Good oral hygiene
 Avoid spicy, hard, acidic and hot food and beverages
 TOPICAL ANESTHETICS (required at mealtimes)
 -Lidocaine (ointment, sprays)
 -Benzocaine (gels, sprays)
 ANALGESICS
 -Opioid drugs

10. TASTE BUDS
 Taste buds sensitive to radiation
 Extensive degeneration of normal histological
architecture of taste buds caused by therapeutic doses
 2nd-3rd week of Radiotherapy Patients notice loss of
taste acuity
 Posterior two-thirds affects bitter and acid flavours
 Anterior third affects sweet and salty flavours
 Taste acuity decreases by a factor of 1000 to 10,000
during course of Radiotherapy
 Alterations in saliva due to radiation changes in
taste perception
 Taste loss is reversible , recovery takes 60-120 days

12. SALIVARY GLANDS
 Major salivary glands exposed to 20-30 Gy
 Parenchymal component of salivary glands
radiosensitive
 Marked decrease in salivary flow first few weeks
after initiation of radiotherapy.
 Extent of reduced flow dose dependent
may reach zero at 60 Gy.
 Mouth dry (xerostomia) tenderness
 Difficulty and pain in swallowing

13.  Composition of saliva affected.
 Increased concentration of sodium, chloride,
calcium, magnesium ions and proteins
 Loss of lubricating properties of saliva
 Serous acini are more affected as they are more
radiosensitive than mucous.
(Parotid>Submandibular/Sublingual)

14.  Viscosity of saliva increases.
 pH of saliva decreases Decalcification of
enamel
 Compensatory hypertrophy of the salivary gland
xerostomia subsides 6-12 months after
therapy
 Xerostomia persisting beyond a year less likely
to return to normal

15. Inflammatory response after initiation of therapy
Loss of acini and ducts
Progressive fibrosis
Adiposis
Loss of fine vasculature
Parenchymal degeneration

17. TEETH
 Adult teeth resistant to radiation effects
 Developing teeth retarded root development,
dwarf teeth, failure to form one or more teeth
 Tooth bud Destruction
 Calcified teeth Inhibited cellular differentiation
Malformation Arrested general growth
 Pulp decreased vascularity reduced cellularity
Tooth prone to pulpitis
 Eruptive mechanism radiation resistant. Irradiated
teeth with altered root formation erupt, even if rootless
 Severity of damage dose dependent

18. RADIATION CARIES
 Rampant form of dental decay that may occur in
individuals who receive a course of radiotherapy that
includes exposure of the salivary glands
 Lesions occur secondary to changes in the salivary glands
and saliva due to :
 -decreased salivary flow
 -decreased pH of saliva
 -increased viscosity of saliva
 -decreased lubricating properties of saliva
 Patients receiving radiation therapy have increased
Streptococcus mutans, Lactobacillus & Candida
 Destruction is seen with doses >30 Gy and is pronounced
when the teeth receive >60 Gy

19. Clinically, 3 types of Radiation Caries seen :
 Widespread superficial lesions attacking buccal,
occlusal incisal, & palatal surfaces
 Primarily involving cementum and dentin in the
cervical areas. Lesion progresses around tooth
circumference Loss of crown
 Dark pigmentation of entire crown
 Combination of all these lesions appear in some
patients

21. MANAGEMENT :
 -Topical application of 1 %
neutral sodium fluoride (viscous
gel) in custom made applicator
trays
 -Combination of restorative
dental procedures, good oral
hygiene, diet restricted in
cariogenic food and topical
application of Sodium fluoride
 -Grossly decayed teeth or teeth
with periodontal involvement to
be extracted before irradiation

22. BONE
 Mandible or maxilla often irradiated during treatment
of cancers in oral region
 Damage to fine vasculature
 Primary damage to mature bone
 Irradiation
 normal marrow replaced with fatty marrow and
fibrous connective tissue
 marrow tissue becomes hypovascular, hypoxic,
hypocellular.
 Degree of mineralization reduced
 Brittleness or altered from normal bone
 Endosteum becomes atrophic : lacks osteoblastic
osteoclastic activity

23. OSTEORADIONECROSIS . :-
 Definition -Inflammatory condition of bone that occurs after bone
has been exposed to therapeutic doses of radiation given for a
malignancy of the head and neck region.
Decreased vascularity of mandible
infection by microorganisms from the oral cavity
Radiation-induced breakdown of the oral mucous membrane
mechanical damage to the weakened oral mucous membrane
(eg.denture sore /extraction/periodontal lesion/radiation caries)
Bone Infection
Non-healing wound in irradiated bone
difficult to treat.

25. Clinical Features
 Mandible >Maxilla
 Temporal bone also
affected.
 Time period- 7.5 years-20
years
 Extra and intra oral fistula
 Parasthesia and
anaesthesia
 Pathological fracture

26.  TYPES:
Early, trauma induced
Spontaneous, without any trauma
Late, trauma induced
AREA OF EXPOSED MANDIBLE AFTER RADIOTHERAPY
LOSS OF ORAL MUCOSA

27. DESTRUCTION OF IRRADIATED BONE RESULTING FROM INFECTION

28. TREATMENT
 Debridement
 Antibiotic- 2 million units
 Supportive therapy
 Analgesics- narcotic and non-narcotic drugs
 Good oral hygiene
 Bone resection.
 Hyperbaric oxygen therapy

30. MUSCULATURE
 Inflammation and fibrosis of musculature due to radiation
 Contracture and trismus of muscles of mastication
 Masseter or pterygoid usually involved
 Restriction in mouth opening starts about 2 months after
completion of radiotherapy
 Management : Physiotherapy may help in increasing
opening distance

31. REFERENCES
 ORAL RADIOLOGY (PRINCIPLES AND INTERPRETATION) –
WHITE & PHAROAH
 ESSENTIALS OF ORAL AND MAXILLOFACIAL RADIOLOGY –
FRENY R KARJODKAR