Progression Of Alveolar Bone Loss Research Articles

Alveolar bone loss in a strain of mice.

Alveolar bone loss with increasing age was compared in strain STR/N and random‐bred Swiss‐Webster mice. All animals were fed pelleted laboratory chow and tap water and killed at 3 month intervals from 3–18 months of age. Alveolar bone loss was quantitated by measuring loss of alveolar crest height on the lingual aspect of the defleshed right hemimandible, and by planimetric measurement of the quantity of trabecular bone in a single undecalcified mesiodistal section of the same hemimandible. The left hemimandible was fixed in formalin and examined histologically. There was a progressive severe loss of alveolar bone with increasing age in strain STR/N mice, which was not observed in random‐bred Swiss‐Webster mice. Histologically, the bone loss was associated with progressive gingivitis and periodontal pocket formation. The bone loss was not related to hair or bedding impaction or to obvious dental morphological differences between the two strains. Systemic disturbances such as generalized osteoporosis or diabetes mellitus were not present. The occurrence of bone loss in STR/N mice in the absence of any applied stimulus suggests that this strain is suitable for studying mechanisms of alveolar bone loss and factors capable of modifying bone loss.

Preliminary observations on the inhibitory effect of tetracycline on alveolar bone loss in beagle dogs

Alveolar bone loss of selected periodontally diseased teeth in four beagles receiving daily tetracycline per os. was compared to three untreated beagle dogs. The percentage and rate of bone loss was measured radiographically over a 47 month period. This included a preliminary period of 20 months when no animals received antibiotics, and 27 months in which 4 animals were each given 250 mg tetracycline hydrochloride daily. During the preliminary period, all dogs progressively lost alveolar bone. However, with the institution of tetracycline treatment further loss of alveolar bone in the treated animals was arrested or markedly diminished for various intervals of time before resuming the original more accel;erated rate of bone loss. Bone loss in one animal was arrested for 27 moknths, whereas in another dog, the period of arrested bone loss was only 5 monghs. In two animals, bone loss was arrested for 17 months.Bacterial samples from one periodontal pocket in each dog revealed that a Gram negative flora predominated in all animals. Tetracycline administration altered the pocket flora slightly with a shift to more gram positive organisms in the treated animals.The data suggest that daily tetracycline administered orally may be effective in slowing the progressive loss of alveolar bone in beagle dogs.

Stresses in the periodontal ligament

Measurements have been made of the root areas of forty five extracted teeth. These have been used to calculate the theoretical pressures that may occur in the region of the alveolar crest and their increase with progressive loss of alveolar bone when a lateral force is applied to the crown of the tooth. Pressures generated in the periodontal ligament as a result of axial loadings have also been calculated and compared with those due to lateral loadings. The results suggest that a very rapid increase in pressures in the periodontal ligament would occur with bone losses in excess of 55 per cent in the case of lateral loadings and over 80 per cent in the case of axial loading. The implications for clinical practice are discussed.