A novel approach revealing the effect of a collagenous membrane on osteoconduction in maxillary sinus floor elevation with β-tricalcium phosphate

Calcium phosphates are used in maxillary sinus floor elevation (MSFE) procedures to increase bone height prior to dental implant placement. Whether a collagenous barrier membrane coverage of the lateral window affects bone formation within a bone substitute augmentation is currently an important matter of debate, since its benefit has not been irrefutably proven. Therefore, in this clinical study twelve patients underwent an MSFE procedure with β-tricalcium phosphate (β-TCP). The lateral window was either left uncovered, or covered with a resorbable collagenous barrier membrane. After a 6-months healing period, bone biopsies were retrieved during implant placement. Consecutive 1 mm regions of interest of these biopsies were assessed for bone formation, resorption parameters, as well as bone architecture using histology, histomorphometry and micro-computed tomography. Comparable outcomes between the groups with and without membrane were observed regarding osteoconduction rate, bone and graft volume, osteoclast number and structural parameters of newly formed bone per region of interest. However, osteoid volume in grafted maxillary sinus floors without membrane was significantly higher than with membrane. In conclusion, our results – obtained with a novel method employed using 1 mm regions of interest – demonstrate that the clinical application of a bioresorbable collagenous barrier membrane covering the lateral window, after an MSFE procedure with β-TCP, was not beneficial for bone regeneration and even decreased osteoid production which might lead to diminished bone formation in the long run

Primary Human Osteoblasts in Response to 25-Hydroxyvitamin D-3, 1,25-Dihydroxyvitamin D-3 and 24R, 25-Dihydroxyvitamin D-3

The most biologically active metabolite 1,25-dihydroxyvitamin D-3 (1,25(OH)(2)D-3) has well known direct effects on osteoblast growth and differentiation in vitro. The precursor 25-hydroxyvitamin D-3 (25(OH) D-3) can affect osteoblast function via conversion to 1,25(OH)(2)D-3, however, it is largely unknown whether 25(OH) D-3 can affect primary osteoblast function on its own. Furthermore, 25(OH) D-3 is not only converted to 1,25(OH)(2)D-3, but also to 24R, 25-dihydroxyvitamin D-3 (24R, 25(OH)(2)D-3) which may have bioactivity as well. Therefore we used a primary human osteoblast model to examine whether 25(OH) D-3 itself can affect osteoblast function using CYP27B1 silencing and to investigate whether 24R, 25(OH)(2)D-3 can affect osteoblast function. We showed that primary human osteoblasts responded to both 25(OH) D-3 and 1,25(OH)(2)D-3 by reducing their proliferation and enhancing their differentiation by the increase of alkaline phosphatase, osteocalcin and osteopontin expression. Osteoblasts expressed CYP27B1 and CYP24 and synthesized 1,25(OH)(2)D-3 and 24R, 25(OH)(2)D-3 dose-dependently. Silencing of CYP27B1 resulted in a decline of 1,25(OH)(2)D-3 synthesis, but we observed no significant differences in mRNA levels of differentiation markers in CYP27B1-silenced cells compared to control cells after treatment with 25(OH) D-3. We demonstrated that 24R, 25(OH)(2)D-3 increased mRNA levels of alkaline phosphatase, osteocalcin and osteopontin. In addition, 24R, 25(OH)(2)D-3 strongly increased CYP24 mRNA. In conclusion, the vitamin D metabolites 25(OH) D-3, 1,25(OH)(2)D-3 and 24R, 25(OH)(2)D-3 can affect osteoblast differentiation directly or indirectly. We showed that primary human osteoblasts not only respond to 1,25(OH)(2)D-3, but also to 24R, 25(OH)(2)D-3 by enhancing osteoblast differentiation. This suggests that 25(OH) D-3 can affect osteoblast differentiation via conversion to the active metabolite 1,25(OH)(2)D-3, but also via conversion to 24R, 25(OH)(2)D-3. Whether 25(OH) D-3 has direct actions on osteoblast function needs further investigation

Paraneoplastic pemphigus as the presenting symptom of a lymphoma of the tongue

A patient is described who initially presented with an acrovesicular eczema which subsequently developed into erythema multiforme with histopathological features of bullous pemphigoid. Although the various laboratory studies pointed to the diagnosis of paraneoplastic pemphigus (PNP), the underlying neoplasm was not detected until 6 months later, when the biopsies of an oral lesion showed the presence of an underlying non-Hodgkin lymphoma. (C) 1998 Elsevier Science Ltd. All rights reserved