Volume changes of iliac crest autogenous bone grafts after vertical and horizontal alveolar ridge augmentation of atrophic maxillas and mandibles: a 6-year computerized tomographic follow-up.

PURPOSE: To evaluate by computerized tomography the long-term volume resorption of autogenous corticocancellous grafted bone harvested from the ilium and used in an alveolar augmentation procedure followed by endosseous dental implant placement. PATIENTS AND METHODS: Eleven maxillary grafts (8 positioned horizontally) and 13 mandibular grafts (10 positioned vertically) were placed in 16 patients. Using software programs, pre- and postsurgical computerized tomographic scans were used to compare volumes of grafts over time (up to 6 yr) to determine the annual percentage of remaining bone and the overall percentage of bone resorption that could be expected. Yearly measurements of volumes and percentages of remaining bone were then compared statistically. RESULTS: At the 6-year survey for blocks grafted in the mandible, an average resorption rate of 87% was obtained; for maxillary grafts at the same survey, complete resorption of the grafts (mean, 105.5%) was recorded. In general, bone resorption appeared slow, except for that recorded in the first 2 years of healing, the only period in which statistical comparisons among all time points showed significant differences for all variables. CONCLUSIONS: Volumetric measurements of the grafts and their related percentages of remaining bone attested to a progressive and unavoidable bone resorption of almost all the grafted bone in the maxilla and mandible. Although the present data were from a heterogeneous group of defects treated with horizontal and vertical procedures, clinicians, when performing alveolar bone augmentation with an autogenous hip bone, should aim at titanium dental implant osseointegration, not only in the augmented bone but also in the native bone below the graft.

Expression of Beta-Catenin, Cadherins and P-Runx2 in Fibro-Osseous Lesions of the Jaw: Tissue Microarray Study.

Fibrous dysplasia (FD) and hyperparathyroidism-jaw tumor syndrome (HPT-JT) are well-characterized benign bone fibro-osseous lesions. The intracellular mechanism leading to excessive deposition of fibrous tissue and alteration of differentiation processes leading to osteomalacia have not yet been fully clarified. Tissue Microarray (TMA)-based immunohistochemical expression of ß-catenin, CK-AE1/AE3, Ki-67, cadherins and P-Runx2 were analyzed in archival samples from nine patients affected by FD and HPT-JT and in seven controls, with the aim of elucidating the contribution of these molecules (ß-catenin, cadherins and P-Runx2) in the osteoblast differentiation pathway. ß-catenin was strongly upregulated in FD, showing a hyper-cellulated pattern, while it was faintly expressed in bone tumors associated with HPT-JT. Furthermore, the loss of expression of OB-cadherin in osteoblast lineage in FD was accompanied by N-cadherin and P-cadherin upregulation (p < 0.05), while E-cadherin showed a minor role in these pathological processes. P-Runx2 showed over-expression in six out of eight cases of FD and stained moderately positive in the rimming lining osteoblasts in HPT-JT syndrome. ß-catenin plays a central role in fibrous tissue proliferation and accompanies the lack of differentiation of osteoblast precursors in mature osteoblasts in FD. The study showed that the combined evaluation of the histological characteristics and the histochemical and immunohistochemical profile of key molecules involved in osteoblast differentiation are useful in the diagnosis, classification and therapeutic management of fibrous-osseous lesions.

Central odontogenic fibroma of the mandible: A case report with diagnostic considerations.

INTRODUCTION: Odontogenic fibroma (OF), a rare odontogenic tumor of mesodermal origin, has been thought to originate from either dental follicle, periodontal ligament, or dental papilla [1]. Different studies reported high variability in the incidence rate as being between 3 and 23% of all odontogenic tumors [2,3]. OF manifests a dual character at the histopathological examination showing odontogenic epithelial structures mimicking those observed in biopsy of ameloblastoma and, in addition, peculiar fragments of cellular stroma. The clinical and radiological features of OF are similar to other odontogenic and/or non-odontogenic tumours and the differential diagnosis may first occur at fine-needle aspiration biopsy. PRESENTATION OF CASE: In the case reported, a young patient showed a localized gingival enlargement involving radiologically the superior margin of the right angle of the mandible and associated with an un-erupted tooth. The morphological characteristics together with clinical and radiologic findings confirmed the tumor to be a central odontogenic fibroma (COF) with secondary gingival involvement. DISCUSSION AND CONCLUSION: Benign odontogenic tumors may be distinguished from other odontogenic/non-odontogenic neoplasias and from malignant tumours through a cytologic differential diagnosis as treatment differs accordingly.

Expression of beta-catenin in human tooth germ.

OBJECTIVE: To evaluate beta-catenin expression in human tooth germ development. STUDY DESIGN: Specimens of 7 human fetuses aged between the ninth and sixteenth week were examined for beta-catenin expression by immunohistochemistry. RESULTS: In the bud stage, we observed catenin membranous positivity for all primitive dental lamina and dental ridge cells, cytoplasmic positivity for tooth bud and intense nuclear positivity for early-condensed dental mesenchyme. The cap stage was marked by intense cytoplasmic and nuclear positivity in the outer and inner enamel epithelium and the dental papilla and by moderate cytoplasmic positivity in the enamel knot. In the early bell stage, we noted strong cytoplasmic and nuclear staining in the inner and outer enamel epithelium, only moderate membranous and cytoplasmic staining in the stellate reticulum, a high percentage of intense nuclear positivity in the dental papilla and strong focal nuclear and cytoplasmic positivity in the dental sac. CONCLUSION: All areas with close contact between epithelial structures and ectomesenchymal cells showed increased expression of delocalized cytoplasmic and nuclear beta-catenin. Nuclear localization, tissue expression pattern and timing suggest a pivotal role for beta-catenin in the transcriptional activation of genes probably involved in the mesenchyme-epithelial interactions on which human tooth development is based.