Sossi A’s research while affiliated with University of Trieste and other places

Aim of this study was the evaluation of the microhardness of 4 dental sealants polymerised with two different curing units. Twenty samples (5 x 5x 2 mm) were prepared with 4 different sealants; 10 samples for each group were polymerised with a plasma curing unit (Apollo 95 E DMD) and 10 with a halogen curing light (Heliolux DLX Vivadent ETS, Schaan, Liechtenstein). For each section 6 Vickers microhardness measurements were performed (VMHT 30A, Leica Wien, Austria), 3 on the surface exposed to the light and 3 on the opposite surface. After the baseline assessment all samples were stored in artificial saliva at 37 degrees C for 30, 60, 90, 180 and 360 days, and then analysed again with the microhardness indenter and observed under steromicroscope 10X (Leica DM2500 Wien, Austria). Data were then statistically analysed. The hybrid composite Tetric flow (group IV) showed the higher microhardness values compared to the other tested materials (group I, II, III); surfaces exposed to curing light showed higher microhardness values than opposite surfaces. Moreover, a significant microhardness reduction was observed after 30 days; values remained unmodified after 60, 90, 180 and 360 days. Data were then statistically analysed with Anova test for repeated measures, with a global significance level of 0.05. Because of the good mechanical properties of dental sealants they represent the first choice materials in pits and fissures sealing.

Aim of this study was to evaluate the marginal microleakage of a dental sealant using different pre-treatment techniques of the enamel surface. Thirty extracted human intact teeth were selected and divided into 3 groups (n = 10) (1: acid etching with 37% orthophosphoric acid - 3M ESPE, St. Paul, Minnesota, USA; 2: air abrasion; 3: air abrasion + acid etching). The sealant (Helioseal, Vivadent Ivoclar AG, Liechtenstein) was applied into occlusal pits and fissures and light cured for 40 sec. All samples were thermocycled for 500 cycles (5 degrees -55 degrees C). Teeth were then immersed into a 2% methylene blue solution for 24 hrs and sectioned in a mesio-distal direction. Forty-eight sections were obtained for each group. Each section was analysed and photographed with a stereomicroscope (50x) assessing dye penetration (0: no dye penetration; 1: dye penetration restricted to the outer half of the sealant; 2: dye penetration restricted to the inner half of the sealant; 3: dye penetration into the underlying fissure). Data were statistically analysed (Mann-Whitney test). Specimens prepared after air abrasion combined with acid etching showed lower microleakage expression if compared with the other two groups (p<0.01). Conclusion A combination of mechanical air abrasion and chemical acid etching represents an effective pre-treatment of enamel surface that may significantly reduce the risk of microleakage.