Ernest Hausmann

Usefulness of Subtraction Radiography in the Evaluation of Periodontal Therapy

Subtraction radiography, a sensitive and accurate technique for identifying alveolar crestal change from standardized pairs of radiographs, is useful in monitoring periodontal therapy. One half of the radiographs were found to be appropriate for subtraction analysis using present technology for taking standardized radiographs. The criterion for usability was identical interpretation of subtraction images made in duplicate from a pair of radiographs. A set of radiographs was analyzed by subtraction radiography as well as by measurement of alveolar bone-crest height. Subtraction radiography was found to be more sensitive in detecting change. Whereas 53% pairs of radiographs showed a change on subtraction radiography, only 14% showed a change in crest height. Comparison of change by subtraction radiography and probing attachment level showed an overall correlation. Since these two measures assess different aspects of the periodontium, perfect correlation was not expected.

The Association Between Osteoporosis and Alveolar Crestal Height in Postmenopausal Women

BACKGROUND Evidence supporting an association between osteoporosis and loss of alveolar crestal bone is limited. This study investigated that association in a large cohort of postmenopausal women. METHODS A cohort of 1,341 postmenopausal women aged 53 to 85 were assessed for alveolar crestal height (ACH) and bone density. ACH was determined from oral radiographs with subjects dichotomized by disease severity. Bone density was assessed by dual energy x-ray absorptiometry, with severity determined by worst T score measured (normal >-1.00; low -1.00 to -2.00; moderate -2.01 to -2.49; osteoporotic <-2.5). RESULTS Compared to subjects in the normal T-score group, the odds of worse ACH increased by 39%, 59%, and 230% for those in the low, moderate, and osteoporotic groups, respectively. Adjustment for weight, education, hormone use, calcium or vitamin D supplementation, and smoking did not appreciably change the findings. Further adjustment for age attenuated the association, with osteoporotic subjects having a 1.9-fold increase of being in the worst ACH group (95% confidence interval [CI] 1.19 to 3.05). After age stratification, in women younger than 70 there was a significant trend by decreasing T-score category (P <0.02). Osteoporotic subjects had worse ACH (odds ratio [OR] = 1.95; 95% CI 1.20 to 3.17). In women aged 70 and older, worse ACH was 2.5- to 4.6-fold increased for decreasing T-score category. After adjustment, the OR (95% CI) for the low, moderate, and osteoporotic groups were 2.66 (1.12 to 6.29), 2.31 (0.89 to 6.01), and 3.57 (1.42 to 8.97), respectively (P trend = 0.026). CONCLUSIONS This study found a strong and consistent association between T score and ACH in postmenopausal women. Increasing age is an important modifier of that association.

The alteration of osteoclast morphology by diphosphonates in bone organ culture

Two diphosphonates alter the morphology of the osteoclast, as they inhibit the calcium45 release from bones stimulated to resorb by lipopolysaccharide. Disodium dichloromethylene diphosphonate was more potent than disodium ethane-1-hydroxy-1,1-diphosphonate in both inhibiting45calcium release and altering osteoclast morphology. Alteration in the morphology of osteoclasts is associated with little or no change in the morphology of the surrounding non-osteoclast cells. These results indicate a specific morphological effect of diphosphonates on osteoclasts.

Skeletal osteopenia and residual ridge resorption

Increased residual ridge resorption resulting from postmenopausal skeletal osteopenia has been a long-standing clinical assumption. This study was conducted to determine the relationship between the degree of residual ridge resorption, sex, and the age of the patient. The technique of measuring mandibular resorption uses panoramic radiographs as described by Wical and Swoope. Six readers received technique instructions and were then tested for uniformity. An analysis of variance demonstrated no significant difference between readers (p greater than 0.10). A random selection of 459 radiographs of edentulous patients were then measured by using a blind technique to determine the amount of residual ridge resorption. Analysis of this data demonstrated a significantly larger percentage of women with class 3 (severe) residual ridge resorption (p less than 0.01) but this difference could not be related to the occurrence of menopause.

Prostaglandins: Bone resorption stimulating factors released from monkey gingiva

Gingival fragments from monkeys have been found to release a factorin vitro into incubation medium which stimulates bone resorption in organ culture. Indomethacin effectively blocks the occurrence of this stimulatory factor in the gingival incubation medium. All of this bone resorptive activity can be accounted for by prostaglandin-like material. The prostaglandins contributing to the bone resorptive activity have been found to be prostaglandins E1 and E2.

Algorithm for the automated alignment of radiographs for image subtraction

The results of this study indicate that automated alignment of pairs of radiographs produces subtractions that are indistinguishable in quality from subtractions aligned manually by an experienced aligner. In developing the algorithm for automated alignment, care was taken that the criteria used for establishing a window appropriate for testing the quality of alignment were the same for both alignment techniques.

Quantitative analyses of osteoclast changes in resorbing bone organ cultures.

SummaryThe stimulation of bone resorption, assessed by the release of45Ca from prelabeled bones, was associated with an increase in number of osteoclasts per bone section in parathyroid hormone (PTH)-treated bones, but not in lipopolysaccharide (LPS)-treated bones. By contrast the number of nuclei per osteoclast increased following LPS treatment, but was not affected by PTH. LPS-treated bones had more multinucleated cells, some having as many as 27 nuclei per osteoclast. More osteoclasts were adjacent to the bone collar in bones treated with LPS or PTH than in control bones. In LPS-treated bones this area also contained the largest osteoclasts, as determined by the greatest number of nuclei per osteoclast. The results suggest that LPS and PTH stimulate osteoclastic resorption by different mechanisms.

Prostaglandin E2 binding and cyclic AMP production in isolated bone cells

SummaryThe binding of prostaglandin E2 (PGE2) to bone cells was studied to provide direct evidence for the existence of specific receptors in bone. Bone cells were isolated by collagenase digestion of fetal and newborn rat calvaria. Isolated cells were incubated with3H-PGE2 and collected on Millipore filters. Specific binding was determined by subtracting the binding that occurred with 10−6 M non-radioactive PGE2 and3H-PGE2 from that with3H-PGE2 alone. With heterogeneous cell preparations and at PGE2 concentrations from 10−9 − 1.7 × 10−8 M at 37°C, specific binding reached steady state within 10 min. Bound3H-PGE2 was displaced by the addition of increasing amounts of unlabeled PGE2. Inhibition of PGE2 binding was observed with PGE1 and the endoperoxide analog, U44069, but not with PGE2α, a lipopolysaccharide, or 13,14-dihydro 15-keto PGE2. Studies with bone cell populations, obtained by sequential digestions, indicated that an osteoclastic population binds 30-fold more PGE2 than osteoblastic cells. Scatchard analyses revealed that the osteoclastic cells have an affinity constant for PGE2 binding similar to that obtained with heterogeneous populations. However, the PGE2 binding capacity in this osteoclastic population was fivefold greater than in the heterogeneous population. The osteoclastic population responded with an increase in cyclic AMP to lower concentrations of PGE2 than the osteoblastic populations. These studies suggest that differences in the binding capacity of PGE2 receptors exist among bone celltypes and that these differences are reflected in the cellular cyclic AMP response.

Effects of small angle discrepancies on interpretations of subtraction images

The present study examines interpretations of subtraction images of pairs of radiographs taken at 0 degrees, 1 degree, or 2 degrees of angle discrepancy. The radiographs were taken at each of 48 alveolar crestal sites on 15 dried human skulls. Computer-simulated lesions were induced at the sites on three fourths of the radiographs. Ten instructed dentists were asked to interpret the subtraction images as to the presence or absence of crestal change. A 2-degree angle discrepancy between radiographs resulted in a significant difference in sensitivity from that of radiographic pairs with a 0-degree discrepancy. However, we found no significant difference in sensitivity between 1-degree and 0-degree pairs of radiographs. In conclusion, a 1-degree geometric difference between pairs of radiographs does not significantly contribute to errors in interpretation of subsequent subtraction images.

Experimental alveolar bone loss in the monkey evaluated by125I absorptiometry

SummaryAn125I absorptiometry technique is described which has sufficient precision to detect the alveolar bone loss associated with ligature-related periodontitis in the monkey. Six monkeys had significant drops in alveolar bone mass 14 days after the application of a silk ligature around the gingival margin of an adjacent tooth. Variation in the magnitude of bone loss was observed. These may represent variations in the pathogenicity of the microflora produced in response to a ligature and/or variation in host response to the insult produced by specific dental plaque organisms. The lack of bone loss post-ligature plus antibiotic therapy supports the theory that the bacterial-host interaction, not simply irritation from the ligature alone, is responsible for the bone loss. The potential for bone regeneration after ligature-induced bone loss is demonstrated.