ABSTRACT
INTRODUCTION: In cases of severe hard tissue loss, 2 mm circumferential ferrule is difficult to achieve which leads to incorporation of different ferrule designs. AIM: To compare and evaluate the effect of different crown ferrule designs on the fracture resistance of mandibular premolars restored with fiber posts, composite cores, and crowns. MATERIALS AND METHODS: Fifty freshly extracted mandibular premolars were endodontically treated and divided into five groups: Group I - 2 mm circumferential ferrule above the cementoenamel junction (CEJ); Group II - 2 mm ferrule on the facial aspect above CEJ; Group III - 2 mm ferrule on the lingual aspect above CEJ; Group IV - 2 mm ferrule on the facial and lingual aspects above CEJ with interproximal concavities, and Group V - no ferrule (control group) and were later restored with fiber posts, composite cores, and crowns. Specimens were mounted on a universal testing machine, and compressive load was applied at a crosshead speed of 1 mm/min until fracture occurred. RESULTS: The results showed that circumferential ferrule produced the highest mean fracture resistance and the least fracture resistance was found in the control group. CONCLUSION: Circumferential ferrule increases the fracture resistance of endodontically treated teeth restored with bonded post, core, and crown.
ABSTRACT
Most primary central nervous system lymphomas (PCNSL) occurring in immunocompetent patients are diffuse large B-cell lymphomas (DLBCL), characterized by poor prognosis. An activated B-cell (ABC) origin of PCNSL has been postulated based on bcl-6 and MUM-1 expression by majority of these tumors. ABC DLBCL has been functionally subdivided using gene expression profiling and immunohistochemical analysis into STAT3-high and STAT-3 low subsets. A potentially crucial difference between STAT3-high and STAT3-low ABC DLBCL is in the expression of bcl-2 family members. STAT3-high cases are generally bcl-2 low and STAT3-low cases show higher expression of bcl-2. Further mechanisms such as activation of nuclear factor-kappa B (NF-κB) activation seem to be responsible for upregulation of bcl-2 in ABC subtype of DLBCL with an adverse outcome. As deregulation of STAT-3 pathway is known to play a critical role in ABC DLBCL and majority of the PCNSL are of the ABC subtype we studied the immunohistochemical expression of STAT-3 proteins in PCNSL along with other traditional markers (CD10, bcl-6, MUM-1 and bcl-2) in 17 cases of PCNSL occurring in immunocompetent patients. Despite lack of STAT3 expression in all our cases, majority (70%) of the patients with bcl-2 positive PCNSL had an adverse outcome similar to that reported in systemic lymphomas of ABC subtype. Based on our observations we propose that PCNSL represents a distinct subset of ABC diffuse large B-cell lymphomas with low STAT3 expression and perhaps mechanisms other than interaction of STAT-3 and NF-κB pathways may play a role in upregulation of bcl-2 in PCNSL. To the best of our knowledge expression of STAT-3 protein in PCNSL which represents a distinct anatomical subset of ABC DLBCL with a dismal prognosis has not been studied before.
