Morphological assessment of Seeger rings in the OT Bridge system: a laboratory and clinical pilot study

OBJECTIVES: This pilot study aimed to evaluate the morphological characteristics and surface roughness of Seeger rings used in the OT Bridge system (Rhein 83) for implant-supported rehabilitations. Specifically, the investigation assessed the effects of short-term aging in artificial saliva on surface morphology and the influence of 12-months intraoral function on linear (Ra, Rz) and surface (Sa, Sz) roughness parameters.

MATERIALS AND METHODS: The study comprised 2 complementary phases: an in vitro experimental analysis and a clinical/laboratory observational evaluation. For the in vitro phase, 2 Seeger rings were examined by scanning electron microscopy (SEM) at baseline (T0) and after 7 days (T1) of aging in artificial saliva (37 °C; pH 7.4). Images were obtained at 35×, 50×, 200×, and 1000× magnifications. For the clinical/ laboratory phase, 11 Seeger rings were retrieved after 12 months of intraoral function from a 57-yearold male patient rehabilitated with full-arch implant-supported prostheses using the OT Bridge system. Specimens were metal-coated and compared with a new Seeger ring, used as a control. Morphological and roughness analyses were performed using a high-resolution digital microscope at 500× magnification. Ra, Rz, Sa and Sz were assessed using standardized measurement protocols. Data were statistically analyzed using one-way ANOVA (α = 0.05).

RESULTS: At lower magnifications, SEM analysis revealed no substantial morphological differences between T0 and T1. At higher magnifications, minor micrometric depressions were observed at T1, without evidence of structural discontinuities. After 12 months of intraoral service, no significant differences were detected in Ra and Rz values between new and retrieved Seeger rings (p >0.05). Conversely, Sa, Sz were significantly higher in clinically aged specimens (p <0.05). No biological or mechanical complications were clinically observed during the 12-month follow-up period.

CONCLUSIONS: Within the limitations of this pilot study, short-term exposure to artificial saliva did not adversely affect the morphology of Seeger rings, and 12 months of clinical use did not compromise their linear surface properties. Although intraoral function was associated with a significant increase in surface roughness, this alteration was not accompanied by clinically relevant mechanical and biological complications.

CLINICAL SIGNIFICANCE: Preliminary in vitro and in vivo evidence suggests that Seeger rings can provide stable mechanical retention in full-arch implant rehabilitations, even under conditions of implant angulation and functional loading, representing a valid and reliable component in fixed implant-supported prostheses. However, surface alterations following prolonged intraoral use suggest that periodic replacement may be advisable to preserve optimal retention and long-term prosthetic stability. 12-month clinical service may lead to surface roughness alterations, necessitating component replacement to maintain optimal function.

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