ABSTRACT
The purpose of this in vitro study was to investigate the sealing performance [microleakage] of different glass ionomer formulations and to measure their wear rate. For microleakage assessment, a total of 120 class V cavities were prepared in upper and lower premolars and were used in this investigation. The cavities were divided into two main groups according to the location of the cervical margin. In group I: The cervical margin of the cavity was located 0.5 mm above the cement-enamel junction. In group II: The cervical margin was located 0.5 mm below the cemtno-enamel junction. Each group was further subdivided into three subgroups A, B, and C [20 each] according to the restorative material used. A resin modified glass ionomer [Vitremer], a polyacid modified resin composite [F2000], and a giomer restorative filling material [beautifil] were used. Each of the previous subgroups was again subdivided into two groups [10 each]. In groups A+, B+, and C+, the restored specimens were subjected to mechanical load cycling and thermal fluctuation before microleakage assessment. In groups A-, B-, and C-, microleakage assessment was carried out 24 hours after immersing the restored teeth in distilled water at room temperature. For wear determination a total of 15 cylindrical specimens were prepared, a two-body abrasion machine was used and the wear data were deducted to calculate the wear rate in gm/sec
Results: There was no statistically significant difference between the microleakage scores above and below the cement-enamel junction for all materials. Furthermore, there was no statistically significant difference between the microleakage scores of the three materials tested. In group I [above CEJ]; Vitremer [A] and giomer [C] showed a statistically higher percentage of [+] specimens with leakage than [-] specimens. There was no statistically significant difference between [+] and [-] specimens in material [B]. However, in group II [below CEJ]: All materials showed a statistically significantly higher percentage of [+] specimens with leakage than [-] specimens. The mean wear rate showed a statistically significant difference between the three materials [P<0.001]. Scheffe's test showed that material [A] showed the highest mean wear rate. There was no statistically significant difference between materials [B] and [C]; both showed the lowest mean wear rate
Conclusion: Microleakage is a multifactorial phenomenon; it is not only affected by the bonded tissues but also by the interfacial mechanism of attachment as well as the mechanical load cycling and thermal fluctuation. The compositional differences between the resin/glass ionomer formulations in terms of resin matrix, filler size, filler loading and mode of filler bonding influenced their wear resistance
Clinical relevance: Microleakage is greatly affected by the bonding mechanism, the mechanical load cycling and thermal fluctuation. Compomer and Giomer are safely used in class V cavities
ABSTRACT
This was an investigation into the effect of two restorative techniques on the postoperative sensitivity and tightness of proximal contacts in class II direct resin composite restorations. 40 class II conservative cavities were prepared in 40 premolar teeth. 20 patients were used in the study. Two cavities were prepared for each patient; a cavity on the right and another on the left side. Two restoration techniques were used. In the first one an increment of a chemical cure resin composite was firstly applied into the cavity before the subsequent increments of light cure composite. In the second technique a prepolymerized composite insert was inserted within the bulk of resin composite after a first increment of light cure resin composite insertion and curing. The restorations were clinically evaluated and graded for post-operative sensitivity and tightness of proximal contacts as alpha, bravo, and charlie after 1 week, 6 months, 1 year, and 2 years respectively using the USPH standards. The results of the study showed insignificant difference in effects of the studied techniques on post-operative sensitivity and tightness of proximal contact. Although both techniques could not totally prevent the adverse effect of aging on postoperative sensitivity and tightness of proximal contacts, none of the tested restorations was graded as charlie at any period of the investigation