Impact of Tooth Preparation Techniques on Fracture Strength of Composite‐Restored Teeth: A Focus on Deep Margin Elevation With Sandblasting and EDTA
Horieh Moosavi, Salehe Sekandari, Amin Shayesteh, Afshin Kordestani, Hossein Bagheri, Maryam AbrishamchiObjective
This study aimed to investigate the effect of dentin surface pretreatment with sandblasting and 17% ethylenediaminetetraacetic acid (EDTA) on the fracture strength of composite inlay and onlay restorations placed using deep margin elevation (DME).
Materials and Methods
Sixty extracted human premolars with standardized mesio‐occluso‐distal (MOD) cavity preparations were randomly assigned to composite inlay or onlay groups ( n = 30). Standardized cusp reduction (2 mm) was performed in the onlay group. Immediate dentin sealing (IDS) and DME were performed in all specimens. Each group was subdivided according to dentin pretreatment: control, sandblasting, or 17% EDTA ( n = 10/subgroup). Semi‐direct composite restorations were fabricated and adhesively cemented. Following thermocycling, fracture strength was assessed using a universal testing machine, and fracture patterns were qualitatively evaluated. Data were analyzed using two‐way analysis of variance (ANOVA).
Results
All 60 teeth were included in the final analysis. The mean fracture strength of onlay restorations was higher than that of inlay restorations across all surface treatment groups. A statistically significant difference between inlay and onlay restorations was observed in the EDTA ( p = 0.012) and control ( p = 0.018) groups, whereas the sandblasting group showed no significant difference ( p = 0.107). Two‐way ANOVA revealed a significant main effect of restoration type on fracture strength ( p < 0.001, partial η 2 = 0.216), while the main effects of surface treatment ( p = 0.457, partial η 2 = 0.029) and the interaction between restoration type and surface treatment ( p = 0.994, partial η 2 = 0.0002) were not statistically significant. Sandblasting demonstrated the highest mean fracture strength, followed by the control and EDTA groups, although these differences were not statistically significant. No significant differences were observed in fracture repairability patterns among groups.
Conclusions
In each preparation, the fracture strength of the inlay group was lower than that of the onlay group. Furthermore, the highest resistance across the different preparations was observed for sandblasting, followed by the control, and finally EDTA, but the differences were not statistically significant.