Radiation and its effects on oral cavity
Oral mucous membrane –during radiation
A- Mucositis—oral mucous membrane show areas of redness and inflammation
B- Desquamated Epithelial Layer—mucous membrane begins to breakdown with the formation of a white to yallow pseudomembrane
C- Infection—it devlopes due to bad oral hygiene Secondary infections by candida albicans
After radiation
Mucosa begins to heal rapidly in about 2 months.Later it becomes atrophic thin,,&avascular.atrophy developes due to obliteration of the fine vasculature&fibrosis of the connective tissue.
Ulcers results from a denture sore,, radiation necrosis or tumour recurrence
Taste Buds---are sensitive to radiation&results in-desquamation of taste buds..
Loss of taste sensation----bitter and acid flavour are more severly affected when posterior2/3of tongue is irradiated .. Ant 1/3 of tongue irradiated ,, causes loss of salt &sweet sensation . Recovery of taste buds requires at least 60-120 days after irradiation
Salivary Glands
Parotid glands are more sensitive than submandibular &sublingual glands
a) progressive loss of salivary secretion
b) xerostomia ---dryness of mouth
c) swallowing is difficult &painful because the residual saliva loses its normal lubricating properties
d) PH &Buffering capacity of saliva falls down
e) Histologically,acute inflammatory response may occur soon after the initiation of therapy. Progressive fibrosis adiposis ,, loss of fine vasculature °enerative parenchyma results in xerostomia
f) Salivary changes influence on the oral microflora leading to radiation caries by increase in strepto-mutans,lactobacillus, candida micro-organisms & thick,, acidic ,, viscous,, small volume of saliva causes radiation caries

Teeth
During tooth developmental period- retards the growth of teeth
Before tooth calcification –destroy the tooth bud
After tooth calcification it inhibit celluar differntiation causing malformation & arresting tooth growth
Children receiving radiation therapy to the jaw shows defects in permanent dentition such as retarded root development,, dwarfing teeth &anodontia
In some instances irradiation of developing teeth after complete calcification causes premature eruption
Irradiation of teeth may retard root formation but no changes in the eruptive mechanism of teeth
Adult teeth are very sensitive to irradiation .. Pulpal tissue shows fibro-atrophy after radiation
Radiation causes no effect on enamel, dentin &cementum

RADIATION CARIES
It is a rampant form of caries that may occur in, individuals who receive radiotherapy .carious lesions results from changes in the salivary glands &saliva.. decrease flow,,decrease PH,,decrease buffering capacity&increase viscocity becauses of reduced or absent cleaning action of normal saliva results in accumulation of debris quickly…Radiation caries has the rapid course &widespread attack which distinguish other caries
BONE
Irradiation of the bone causes damage to the vasculation of periosteum &cortical bone..
Radiation also destroys osteoclasts&to a lesser extent osteoblasts .Bone marrow is replaced with fatty marrow &fibrous connective tissue .. Marrow tissue becomes hypovascular ,, hypoxic,, &hypocellular
Osteoradionecrosis is the critical complication that occur in bone ,, after irradiation The decrease vascularity of the mandible renders it easily infected by micro-organisms from the oral cavity.. This bone infection may result from radiation induced breakdown of mucous membrane from denture sore or tooth extraction ..It is more common in mandible because of less vascular supply &it is more frequently exposed to radiation

Treatment of Osteoradiaonecrosis
A)----prevent radiation caries by restoring all caries lesions before irradiation starts
B)--- maintain good oral hygiene
C)---Removing all poorly supported &badly carious teeth &allow sufficient time to heal up the extraction wounds
D)Daily topical fluride application
E) Adjusting dentures to minimize risk of denture sores
F) hyperbaric oxygen
G) Resction of sequestra or mandibulectomy
H) Nutrition supplements
I) Antibiotics& analgesics can be given
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