The effect of secondary hyperparathyroidism and hemodialysis therapy on alveolar bone and periodontium.

BACKGROUND: Alveolar bone is particularly sensitive to increased levels of parathyroid hormone (PTH) from either primary or secondary hyperparathyroidism (HPT). The purpose of this study was to examine the effect of secondary HPT on the periodontium of patients on hemodialysis. METHODS: The experimental group consisted of 35 patients with secondary HPT, with chronic renal failure treated by hemodialysis (E group). A control group (C group) was formed from 35 healthy age- and gender-matched subjects attending the maxillofacial outpatient clinic for a variety of reasons. Blood samples were taken from the E group, and the biologically active intact parathormone molecule, PTH(1-84), was assayed using two-site immunoradiometric assay (IRMA). The time of onset and the duration since diagnosis of HPT was also recorded. In addition, for a subgroup of 25 matched pairs of patients, a clinical periodontal examination was performed, and the Ramfjord index teeth were recorded for: Plaque index (PI); Gingival index (GI); Probing depth (PD); and Clinical attachment level (CAL). A standardized panoramic X-ray was taken from all patients and computer-based linear measurements were used to assess alveolar bone loss (BL). Unpaired Student's t-test served to compare the two groups. Pearson's correlation coefficient test was used to study the association between PI, PTH level, disease duration and BL. RESULTS: Demographically, both groups were similar with no statistical difference. PI was also similar in the C and E group (2.03 +/- 0.13 and 1.76 +/- 0.17, respectively). GI, however, was slightly greater in the C group (1.28 +/- 0.09) compared to the E group (0.97 +/- 0.01). PD in the E group (2.92 +/- 0.14 mm) was almost identical to that of the C group (2.90 +/- 0.12 mm). Likewise, CAL in the E group (4.43 +/- 0.29 mm) did not differ from CAL in the C group (4.03 +/- 0.25 mm). Mean BL was also similar in the E and C groups (3.60 +/- 0.23 mm and 3.85 +/- 0.24 mm, respectively). PI showed a positive, significant correlation with BL (r = 0.457, P = 0.0008). CONCLUSION: From this study it can be concluded that secondary HPT does not have an appreciable effect on periodontal indices and radiographic bone height.

Multiple foci in the range dependence of the intensity fluctuations of a plane wave propagating in a random medium.

The differential equation for the fourth-order statistical moment of the field of a plane wave propagating in a two dimensional random medium is solved numerically. Results are presented for the scintillation index when the index-of-refraction correlation function of the medium is Gaussian and gamma (ratio of diffraction length to scattering length) is 50. It is pointed out that the solution has multiple foci, and it is suggested that this characteristic will be more pronounced for larger values of gamma.