EFFECTS OF RADIATION ON ORAL TISSUES

EFFECTS OF RADIATION ON ORAL TISSUESBY:ADWITI VIDUSHIB.D.S FINAL YEARGUIDED BY :DR. SHALU RAIDR. DEEPANKAR MISRADR. VIKASH RANJAN DR. MUKUL PRABHATDR. MANSI KHATRI

CONTENTSRationaleOral Mucous MembraneTaste BudsSalivary GlandsTeethRadiation CariesBoneMusculature

RATIONALEOral 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.

ORAL MUCOUS MEMBRANE

MUCOSITIS- Reddening and inflammation of oral mucosa 1st Sign of mucositis end of second week of therapy.

ATROPHY OF RADIOSENSITIVE BASAL LAYERFORMATION OF WHITE-YELLOW PSEUDOMEMBRANE

SLOUGHING OF MUCOSA

SECONDARY INFECTION DUE TO Candida albicans (common complication)

HEALING (After about two months)

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.

Clinical FeaturesReddish inflamed mucosaAreas of white pseudo membraneAreas where oral epithelium is separated from underlying connective tissueSores in mouth, gums and tongueDysphagiaUlcers due to radiation necrosis Complications in denture wearing

WHO MUCOSITIS SCALE:

1.Soreness/ Erythema2.Erythema,ulcers but patient is able to eat solid.3.Ulcers, requires liquid diet.4.Food administration is not possible orally.

ManagementGood oral hygieneAvoid spicy, hard, acidic and hot food and beveragesTOPICAL ANESTHETICS (required at mealtimes)-Lidocaine (ointment, sprays)-Benzocaine (gels, sprays)ANALGESICS -Opioid drugs

TASTE BUDSTaste buds sensitive to radiation Extensive degeneration of normal histological architecture of taste buds caused by therapeutic doses2nd-3rd week of Radiotherapy Patients notice loss of taste acuity Posterior two-thirds affects bitter and acid flavoursAnterior third affects sweet and salty flavoursTaste acuity decreases by a factor of 1000 to 10,000 during course of RadiotherapyAlterations in saliva due to radiation changes in taste perceptionTaste loss is reversible , recovery takes 60-120 days

SALIVARY GLANDSMajor 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) tendernessDifficulty and pain in swallowing

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

Viscosity of saliva increases. pH of saliva decreases Decalcification of enamelCompensatory hypertrophy of the salivary gland xerostomia subsides 6-12 months after therapyXerostomia persisting beyond a year less likely to return to normal

Inflammatory response after initiation of therapyLoss of acini and ductsProgressive fibrosisAdiposisLoss of fine vasculatureParenchymal degeneration

TEETHAdult teeth resistant to radiation effectsDeveloping teeth retarded root development, dwarf teeth, failure to form one or more teethTooth bud DestructionCalcified teeth Inhibited cellular differentiation Malformation Arrested general growth Pulp decreased vascularity reduced cellularity Tooth prone to pulpitisEruptive mechanism radiation resistant. Irradiated teeth with altered root formation erupt, even if rootlessSeverity of damage dose dependent

RADIATION CARIES

Rampant form of dental decay that may occur in individuals who receive a course of radiotherapy that includes exposure of the salivary glandsLesions 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 salivaPatients receiving radiation therapy have increased Streptococcus mutans, Lactobacillus & CandidaDestruction is seen with doses >30 Gy and is pronounced when the teeth receive >60 Gy

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

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

BONEMandible or maxilla often irradiated during treatment of cancers in oral regionDamage to fine vasculature Primary damage to mature bone Irradiation normal marrow replaced with fatty marrow and fibrous connective tissuemarrow tissue becomes hypovascular, hypoxic, hypocellular.Degree of mineralization reducedBrittleness or altered from normal boneEndosteum becomes atrophic : lacks osteoblastic osteoclastic activity

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 cavityRadiation-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.

Clinical FeaturesMandible >MaxillaTemporal bone also affected.Time period- 7.5 years-20 yearsExtra and intra oral fistulaParasthesia and anaesthesiaPathological fracture

TYPES:Early, trauma inducedSpontaneous, without any traumaLate, trauma induced

AREA OF EXPOSED MANDIBLE AFTER RADIOTHERAPYLOSS OF ORAL MUCOSA

DESTRUCTION OF IRRADIATED BONE RESULTING FROM INFECTION

TREATMENTDebridementAntibiotic- 2 million unitsSupportive therapyAnalgesics- narcotic and non-narcotic drugsGood oral hygieneBone resection.Hyperbaric oxygen therapy

MUSCULATUREInflammation and fibrosis of musculature due to radiationContracture and trismus of muscles of masticationMasseter or pterygoid usually involved Restriction in mouth opening starts about 2 months after completion of radiotherapyManagement : Physiotherapy may help in increasing opening distance

REFERENCESORAL RADIOLOGY (PRINCIPLES AND INTERPRETATION) WHITE & PHAROAH ESSENTIALS OF ORAL AND MAXILLOFACIAL RADIOLOGY FRENY R KARJODKAR

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