Effect of Reinforcement Methods on the Retention of Resin-bonded Fixed Partial Dentures using a Composite Denture Tooth as a Pontic: In Vitro Evaluation

The incorporation of composite denture teeth as pontics in resin-bonded fixed partial dentures has been deemed to be short-lived. This study investigated whether pre- or posttreatments could improve the bonding of denture tooth pontics. A model fixed partial denture was fabricated that included composite denture teeth (Endura) bonded with 1 of 2 resin systems (C&B-Metabond or Aeliteflo). The bonding surface of the pontic was pretreated with one of three methods (air-particle abrasion [AA], AA plus silanization, or cavity preparation plus AA). The bonding areas between pontic and abutments were posttreated with 1 of 2 methods (reinforcement with fiber or metal post). Five bonded specimens for each treatment group were subjected to 20,000 thermocycles (4°C to 60°C; dwell time 60 s) before retentive forces (N) were determined. All data were analyzed with two-way ANOVA and Bonferroni's test (p = 0.05). All specimens that underwent the pre- and posttreatment outperformed untreated specimens. For the specimens bonded with C&B-Metabond and posttreated with a polyethylene fiber (Ribbond) or a metal post (DC Post), the mean retentive forces were 316 N and 301 N for mandibular specimens, and 354 N and 380 N for maxillary specimens, respectively. These values were significantly higher than those obtained with other pretreatment methods (p = 0.0003). For mandibular specimens bonded with Aeliteflo, specimens posttreated with Ribbond exhibited significantly higher retentive forces (332 N) compared to other specimens (p = 0.0001). Within the limitations of this study, the bond strength of a resin-bonded fixed partial denture incorporating a composite denture tooth as the pontic was improved by reinforcement with either a polyethylene fiber or a metal post.