Effect of Four Luting Cements on Retentive Strength of Stainless Steel Crowns of Primary Second Molars

Stainless steel crowns are valuable materials for the restoration of primary second molars. Luting cements provide the connection between crowns and prepared tooth structure so the aim of this study was to evaluate and compare the retentive strength of stainless steel crowns to the teeth after using luting cements including poly carboxylate, zinc phosphate, glass ionomer and adhesive resin cements. A total 48 primary second molars were randomly divided into 4 groups, the standard crown preparation (stainless steel crown) was done on each tooth and a crown with suitable size and retention were selected for each tooth before cementation. A U shape orthodontic wire was soldered to the crown and then the crowns of each group were cemented with one of the four cements. Next, the teeth were kept in artificial saliva and incubated for 24 hours at 37ᵒc. After that using a specially designed Instron Universal Testing Machine, the teeth were pulled away with 2mm/min speed. The load was gradually increased so that the signs of dislodgement of the crown from tooth would be observed. The surface area of SSC was measured by a graphical method. The retentive strength was measured in terms of load/area (kg/cm2). The mean retentive strength (kg/cm2) of poly carboxylate cement was 17.2±3.3, 19.8±3.8, zinc phosphate 17.01±3.8 for glass ionomer and 19.27±3.7 for resin cement. Based on statistical analysis of One Way ANOVA, there was no significant statistical difference among 4 groups. (P=0.1) The retentive strength of these four cements showed non-significant difference. Therefore, the selection of the cement could depend on the individual patient’s needs and decision of practitioner.