15 June 2021

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To splint or not to split short dental implants under the same partial fixed prosthesis? One-year post-loading data from a multicentre randomised controlled trial

Marco Tallarico, Fulvio Gatti, Mario Silvio Meloni, Leonardo Muzzi, Nicola Baldini, Jacopo Buti, Armando Minciarelli, Ertha Xhanari, Marco Esposito

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Purpose. To compare the clinical outcomes of two adjacent 6-mm-long dental implants splinted under the same prosthesis (control group) versus two identical implants supporting single crowns (test group).

Materials and methods. Forty-seven patients with edentulous posterior (premolars and/or molars) jaws received two adjacent 6-mm-long dental implants, which were submerged. Four months later, at impression taking, patients were randomised to receive splinted or unsplinted definitive cemented metal-composite prostheses. Unfortunately, four patients died before randomisation and three patients lost five implants, so only 40 patients were randomised, according to a parallel-group design, to have both implants splinted under the same partial fixed prosthesis (19 patients) or with two single crowns (21 patients). Outcome measures were: prosthesis and implant failures, any complications, peri-implant marginal bone level changes and patient satisfaction. Patients were followed-up to 1 year after loading. 

Results. One patient from the splinted group dropped out. No implant failures occurred after randomisation. One complication occurred in the unsplinted group versus no complications at splinted implants, the difference not being statistically different (Fisher’s exact test P = 1.000; difference in proportions = -0.04; 95% CI -0.16, 0.09). Both groups presented significant peri-implant marginal bone loss at 1 year after loading (P<0.05), respectively -0.36 (0.45) mm at splinted implants and -0.17 (0.31) mm at unsplinted implants, but there were no statistically significant differences between the two groups (mean difference 0.19 mm; 95% CI -0.10 to 0.48; P = 0.194). All patients were fully or reasonably satisfied with the treatment, with the exception of two patients, both from the splinted group: one patient was not sure about the aesthetics, and another would not undergo the same treatment again.

Conclusion. The present data seems to suggest that up to 1 year after loading the prognosis of short implants, mostly placed in mandibles characterised by dense bone quality, may not be influenced by splinting or not under the same fixed prostheses. However, these preliminary results need to be confirmed by larger trials with follow-ups of at least 5 years.