Comparison of osteoclastogenesis and local invasiveness of ameloblastoma and keratocystic odontogenic tumor

[Molecular basis of ameloblastoma pathogenesis: A review]

Ameloblastoma is the most common and highly invasive benign odontogenic tumor. Its pathogenesis is not yet fully understood.

Objective

To describe the most important molecular findings that promote the proliferative activity of ameloblastoma and the factors involved that encourage invasion into surrounding bone tissues.

Methodology

A search for scientific evidence was conducted through the following databases: Science Direct, Medline, Wiley, Web of Science, and Google Scholar. A total of 32 articles were reviewed, with inclusion criteria being articles published in English and Spanish; descriptive and analytical studies, narrative and systematic reviews published from January 2015 to June 2021. Letters to the editor were excluded.

Results

The biological molecular findings that allow ameloblastoma to invade surrounding tissues involve alterations in the RANK/RANKL/OPG pathways, transforming growth factor beta (TGF-β), Wnt/β-catenin pathway, and matrix metalloproteinases, as well as alterations in MAPK and SHH pathways that facilitate the proliferation and tumor development of ameloblastoma.

Conclusions

These findings are fundamental for a better understanding of the pathways involved in the pathogenesis of ameloblastoma.

Immunohistochemical analysis of osteoclastic and osteoblastic activity in ossifying fibroma and juvenile ossifying fibroma: A comparative study

Cemento-ossifying fibroma (COF) and juvenile ossifying fibroma (JOF) have been considered distinct entities within the category of fibro-osseous lesions. This study aimed to assess osteoblast and osteoclast activity in COF and JOF by investigating bone resorption markers, specifically receptor activator of nuclear factor-kB (RANK), RANK ligand (RANKL), and its inhibitor osteoprotegerin (OPG). A comparative analysis of these markers was performed on all lesions. Immunohistochemistry was employed to evaluate and quantify the expression of these biomarkers in a sample of 20 cases of cemento-ossifying fibroma (COF), 15 cases of psammomatoid juvenile ossifying fibroma (PsJOF), and 10 cases of trabecular juvenile ossifying fibroma (TrJOF). The expression of osteoprotegerin was significantly higher in cemento-ossifying fibroma (33.9±13.0) compared to trabecular juvenile ossifying fibroma (27.3±9.2) and psammatoid ossifying fibroma (25.2±14.9), with the COF showing the highest expression followed by the latter two (p=0.037). There was a higher percentage (80%) of stromal fibroblast cells that showed positive expression of RANKL in cemento-ossifying fibroma (COF) compared to psammomatoid juvenile ossifying fibroma (PsJOF) (33.3%) and trabecular juvenile ossifying fibroma (TrJOF) (30.0%) when considering a positive expression score of 3 (p=0.024). Cemento-ossifying fibroma demonstrated the highest expression of osteoprotegerin and RANKL-positive stromal fibroblast cells, followed by psammomatoid juvenile ossifying fibroma and trabecular juvenile ossifying fibroma. These findings provide valuable insights into the pathogenesis of these lesions.

Differential Expression of Claudin in Odontogenic Cysts

Objective  This study aimed to analyze claudin-1, -4, and -7 expression in different types of odontogenic cysts (odontogenic keratocysts [OKCs], dentigerous cysts [DCs], calcifying odontogenic cysts [COCs], and radicular cysts [RCs]) as well as its association with OKC recurrence.

Materials and Methods  Seventy samples of odontogenic cysts samples were immunohistochemically stained to detect claudin-1, -4, and -7 expression. Patient information and OKC recurrence data were recorded. The staining was analyzed semiquantitatively and categorized based on the pattern and percentage of positively stained cystic epithelial cells.

Statistical Analysis  Expression of different claudins between groups was analyzed using the Kruskal–Wallis test with Dunn's test, followed by post hoc pairwise comparison. The association between claudin expression and OKC recurrence was analyzed by the Mann–Whitney U test. Correlations among claudin expression were examined with Spearman's correlation coefficient. Level of significance was at p  < 0.005.

Results  Claudin-1 was widely expressed in every odontogenic cyst. Most DCs (50%) expressed claudin-1 in more than 75% of cells, as did RCs (65%), while most OKCs (50%) expressed claudin-1 in 26 to 50% of cells. Most COCs (50%) expressed claudin-1 in 51 to 75% of cells. Every sample of OKC and RC was positive for claudin-4, but no sample showed staining in more than 51% of cells. Every odontogenic cyst was positive for claudin-7. DCs (35%), OKCs (55%), and RCs (40%) mostly showed staining in 26 to 50% of cells. High claudin-1 expression was shown in COCs, DCs, and RCs, while low expression of claudin-4 was shown in every odontogenic cyst. For claudin-7, the expression is high only in COCs. Claudin-1 and -4 was significantly different among each odontogenic cyst. High expression of claudin-1 was correlated with OKC recurrence. The correlations of claudin-1 with claudin-7 expression and claudin-4 with claudin-7 expression were significant in DCs. In COCs, claudin-1 and claudin-7 expression was significantly correlated.

Conclusions  The expression of claudin-1, -4, and -7 was present in every odontogenic cyst, but the proportion of positive staining cells was different. Expression of claudin-1 is associated with OKC recurrence. Dysregulation of claudin expression may play a pathogenic role in cyst pathogenesis.

Postorthodontic Relapse Prevention by Administration of Grape Seed (Vitis vinifera) Extract Containing Cyanidine in Rats

Objective  The aim of this study was to analyze the effect of grape seed extract containing cyanidin on osteoclastogenesis (by means of receptor activator of nuclear factor-κ B ligand [RANKL] and osteoprotegerin [OPG] levels) and the number of osteoclasts during orthodontic relapse in Wistar rats.

Materials and Methods  This study is an in vivo quasi experimental research. A total of 32 male Wistar rats were used in the study, which were randomly split equally into two groups, grape seed (GS) and control group (CG). All rats were given an orthodontic force of 35 cN using a stainless steel 3-spin coil spring that was activated for 7 days and then conditioned to be passive. During this phase, the GS group was administered grape seed extract containing cyanidin once per day. Orthodontic appliances were removed from both groups afterward, and then the alveolar bone tissue was isolated consecutively according to observation days (days 1, 3, 7, and 14), while OPG and RANKL levels were analyzed in their gingival crevicular fluid using a specific enzyme-linked immunosorbent assay (ELISA). Tissues were then stained with hematoxylin–eosin (H&E) and observed under a light microscope to count the number of osteoclast cells. Data were analyzed statistically using an independent t -test ( p < 0.05).

Results The number of osteoclasts in the GS group was significantly lower than that in the CG group on all experiment days ( p = 0.021; p = 0.001; p = 0.024; p = 0.001; p < 0.05). ELISA results showed that the RANKL level of the GS group was significantly lower on days 3 and 7 ( p = 0.025; p = 0.039; p < 0.05), while the OPG level was significantly higher on days 1 and 3 in the GS group than in the CG group ( p = 0.039; p = 0.021; p < 0.05).

Conclusion Grape seed extract can prevent postorthodontic relapse movement by inhibiting osteoclastogenesis and reducing the number of osteoclasts in Wistar rats.