Does Ferrule\'s Presence Affect the Success Rate of Bonded Restorations? A Systematic Review

Aim and objective: Ferrules can reinforce the endodontically treated teeth by encircling the remaining coronal structure. The adhesive connection of bonded restorations to dental dentine via resin bonds on one hand and the importance of conservative tooth structure removal during crown preparations present the question “is ferrule necessary for bonded restorations?”. This systematic review aimed to study the available literature on the effect of the ferrule on resin-bonded restored teeth. Materials and methods: A search of the literature in PubMed and PMC’s databases, without any date restriction, was carried out. The keywords were based on the PICO question “Does ferrule’s presence affect the success rate of bonded restorations?”. The full title and abstract of each article were screened by two independent authors using predetermined inclusion and exclusion criteria. Results: Ten articles were included in this review. All teeth were endodontically treated and received lithium disilicate ceramic crowns bonded adhesively. Ferrules designs ranged from no ferrule to 3 mm and/or different ferrule circumferences. Three studies reported a lack of a significant difference in fracture resistance and/or stress levels and/or cyclic fatigue between different ferrule designs. Six studies reported higher fracture resistance, lower stress levels on root dentin and fiberglass post, higher count of fatigue cycles, less fracture count, less tooth strain value for ferrule groups. Conclusion: In the limits of this systematic review, a ferrule is still necessary for resin-bonded restorations, and more ferrule in terms of height or/and circumference presents better results than no ferrule at all or interrupted or less ferrule.