Byline: Mahtab. Memarpour, Reza. Derafshi, Mahshid. Razavi
Background: Obtaining optimal marginal adaption with prefabricated stainless steel crowns (SSCs) is difficult, especially after removing dental caries or defects in cervical areas. This situation requires the use of an SSC after tooth reconstruction. This study evaluated microleakage and material loss with five restorative materials at SSC margins. Materials and Methods: One hundred and twenty primary molar teeth were randomly divided into six groups (n = 20). Class V cavities were prepared on the buccal surfaces of the teeth in groups 1-5. Cavities were restored with amalgam, resin-based composite, glass ionomer (GI), zinc phosphate, or reinforced zinc oxide eugenol (Zonalin). Group 6 without cavity preparation was used as a control. Restorations with SSCs were prepared according to standard methods. Then, SSCs were fitted so that the crown margins overlaid the restorative materials and cemented with GI. After thermocycling, the specimens were placed in 0.5% fuchsin and sectioned. The proportions of mircoleakage and material loss were evaluated with a digital microscope. Statistical analysis was performed with Kruskal-Wallis and Mann-Whitney tests. Results: The groups differed significantly (P < 0.001). Amalgam and GI showed the least microleakage. Amalgam restorations had significantly less microleakage than the other materials (P < 0.05). Microleakage was greatest with resin-based composite, followed by Zonalin. Material loss was greater in samples restored with Zonalin and zinc phosphate. Conclusion: When SSC margins overlaid the restoration materials, cavity restoration with amalgam or GI before SSC placement led to less microleakage and material loss. Regarding microleakage and material loss, resin-based composite, zinc phosphate, and Zonalin were not suitable options.
Prefabricated stainless steel crowns (SSCs) are intended to cover the whole coronal surface of the tooth. They are used to restore primary or permanent teeth with extensive or multisurface cavities, cervical decalcification, and/or developmental defects. [sup],
Ensuring adequate SSC marginal adaptation reduces microleakage around the tooth-crowns margins; however, this aim can be difficult to achieve with prefabricated crowns. [sup] Problems may also be associated with the use of SSCs for full crown coverage in teeth with large cavities or cervical decalcification. For example, it may be necessary to reduce tooth size and extend parts of the crown margins beyond the sound tooth after caries or defect removal. [sup], In permanent teeth, reconstruction with restorative materials as a core may be indicated. [sup], Also when the crown margin is not supported by a sound permanent tooth, some methods recommend increasing the clinical crown length by orthodontic forces or periodontal surgery, [sup], both of which are contraindicated for children. In addition, removing part of the tooth structure without replacing it may lead to the accumulation excessive luting cement at the crown margins, which is inconsistent with the rule of low film thickness of the luting cement for crown cementation. [sup], Lack of due attention to this rule may compromise long-term crown retention. [sup] Therefore, a suitable restorative material is needed to replace the tooth structure, especially when the crown margin does not completely cover the whole restoration....