. Dental and oral radiography : a textbook for students and practitioners of dentistry . fest inthe radiogram as radiolucent areas but differ in appear-ance from cysts or dento-alveolar abscesses in that thereis a less distinct line of demarcation between the radio-lucent area and the surrounding tissue. In such in-stances, the borders of the radiolucent area show a grad-ual increased radiopacity until normal tissue is fact is easily understood when we recall the pro-gressive character of these lesions and the character oftissue changes which accompany them. Thus far only those cond
. Dental and oral radiography : a textbook for students and practitioners of dentistry . fest inthe radiogram as radiolucent areas but differ in appear-ance from cysts or dento-alveolar abscesses in that thereis a less distinct line of demarcation between the radio-lucent area and the surrounding tissue. In such in-stances, the borders of the radiolucent area show a grad-ual increased radiopacity until normal tissue is fact is easily understood when we recall the pro-gressive character of these lesions and the character oftissue changes which accompany them. Thus far only those conditions which might be termedprogressive; inflammatory processes and which are ap-parent as radiolucent areas have been discussed. INTERPRETATION OE RADIOGRAMS 149 Another type of radiographic variation sometimes en-countered and which is apparent as an area of increasedradiopacity is important. In such instances the reactionof the alveolar bone may be defensive in character re-sulting in an increase in the number of bone units andhence to an increased resistance to the passage of the. ■■■■nHHi Fig. 68.—A cuspid tooth lying against the anterior wall of the antrum. rays. In this defensive process there is an increaseddeposition of lamellae which in some instances may ren-der the bone structure in the area affected very denseand compact in character. This condition which isdoubtless due to a morbid increase of nutrition may asin the case of the progressive inflammations be due toinfection, trauma or hyperocclusion, thermal shock, de- 150 DENTAL AND ORAL RADIOGRAPHY fensive reaction, or to such unknown influences as mayproduce such bone changes. In any event, such condi-tions when demonstrated require no small degree ofstudy and judgment in correctly accounting for theirexistence. (Fig. 66.) Either of the above mentioned types of radiographicvariations (i. e., the progressive or defensive) may beencountered in alveolar bone even after all the teeth havebeen removed especi
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