Visual and profilometric wear measurements.

Wear of composites can be estimated by the degree of marginal discrepancy between the prepared cavity wall and the occlusal margins of composites. Such evaluations are done on casts by comparing and rating the marginal discrepancy with those on standard casts. We analyzed the reliability of this technique on metal and stone specimens. These specimens contained grooves of different width and depth. For the visual comparison we used stone casts of machined standards of known groove depth. We measured the depths of the metal specimens with a profilometer and made stone casts of these original specimens. Using the stone casts of the standards, five dentists estimated the unknown groove depths on the remaining stone casts. These estimates were done under standardized conditions and repeated by each dentist on five different occasions. The results showed that visual depth evaluations of die stone specimens underestimated the depths when compared with the values measured with a profilometer on the original metal models. One investigator gave significantly different (p less than 0.05) groove depth estimates at different occasions.     

Prostaglandin E2 and interleukin-1 levels in smokeless tobacco-induced oral mucosal lesions

Inflammatory mediators released as a result of smokeless tobacco (ST)-induced irritation may play a role in the development of oral mucosal lesions at habitual tobacco placement sites in ST users. The present study examined levels of interleukin-1 (IL-1) and prostaglandin E2 (PGE2) in ST-induced mucosal lesions and compared these to mediator levels in clinically normal mucosa. Soft tissue biopsies were obtained from white mucosal lesions at habitual placement sites and normal alveolar mucosal tissue at non-placement sites in 18 ST users. Fifteen non-tobacco using subjects also provided normal alveolar mucosal biopsies. IL-1 and PGE2 were recovered from the specimens, and mediator levels were determined by enzyme immunoassay. Prostaglandin E2 levels (pg/mg) were lower in both regions in the ST subjects, but values did not vary significantly between the regions with 2.77±0.72 and 2.86±0.99 at placement and non-placement sites, respectively, in ST users and 7.31±3.84 in non-tobacco users. Both IL-1α and IL-lβ (pg/mg) were significantly (p < 0.0I) elevated in ST lesions (IL-lã=25.56±4.00; IL-1β=7.76±1.68) compared to either non-placement sites in ST users (IL-lα=14.64±2.65; IL-lβ=1.63±0.72) or non-tobacco users (IL-lα=12.84±2.60; IL-lβ=2.04±0.75). In view of IL-l's role in keratinocyte proliferation and its inflammatory effects, this cytokine may contribute to mucosal and gingival alterations observed in ST users.     

Chemotaxis and degranulation of polymorphonuclear leukocytes in the presence of sulfide

In polymicrobial infections such as periodontal disease, the polymorphonuclear leukocytes (PMN) may have to work in the absence of oxygen and in the presence of significant levels of hydrogen sulfide. There are conflicting results reported on the chemotactic capacity of PMN under anaerobic conditions. It is not known whether PMN are able to migrate and release the contents of their granules in the presence of sulfide. PMN were exposed to various levels of sulfide and their chemotaxis and degranulation were studied when they were stimulated with N-formyl-inethionyl-leucyl-phenylalanine or zymosan-activated serum. Chemotaxis was evaluated with the agarose method. The release of granule markers, lactoferrin and myeloperoxidase, was evaluated with enzyme-linked immunosorbent assay. PMN had similar capacity for chemotaxis under aerobic and anaerobic conditions. The migration of PMN was only to a minor extent inhibited by 1–2 mM sulfide. The release of lactoferrin and myeloperoxidase was the same under aerobic and anaerobic conditions and was not significantly influenced by sulfide. PMN seem to be very well suited to defend the tissue against bacteria under the harsh conditions prevailing in the periodontal pocket.