The goal of this study was to evaluate the shear bond strength (SBS) and failure mode of four different splint materials [Polyethylene FRC Ribbond Thm (RB), Polyethylene FRC Construct (Kerr), Multifilament Fishing Line (MFL), and Non Fiber Reinforced Composite (control)]. Thirty-seven subjects were randomly divided into four splint methods. After splinting procedures, the subjects were recalled 12 months later. One hundred and sixty human mandibular incisors (for extracoronal and intracoronal splinting) and 40 sheep mandibles (only extracoronal splinting) were used for the in vitro part. The specimens were subjected to SBS at their incisoproximal contact, and debonding forces were measured with a universal testing machine (1 mm/min crosshead speed). Failure sites were examined under a stereomicroscope (×40 magnification). The SBS data were assessed via analysis of variance (ANOVA) and Tukey’s tests. The survival rate was significantly affected by the splint type (RB:95.3%, Kerr:91.6%, MFL:93.5%, Control:52.5%). No statistically significant differences were found between RB, Kerr, and MFL (p > 0.05) at all in vitro parts. Intracoronal splinting showed lower SBS values than extracoronal (p < 0.05). Lower SBS values were obtained in sheep teeth than human teeth (p < 0.05). Significantly different fracture patterns were noted between groups (p < 0.05). Only resin composite application seems to be inadequate for periodontal splinting. MFL splints are also economic and quite resistant, and they might be used as an alternative to fiber-reinforced composites.