Reports & Studies

Patient- and implant-related factors – what affects the outcome of treatment?

PD Dr. Kristina Bertl, PhD MSc MBA

The outcome of non-surgical treatment of an implant with peri-implantitis is harder to predict than that of a natural tooth with periodontitis. And unfortunately, purely non-surgical treatment is often not sufficient to achieve a stable result. It is therefore all the more important to consider before starting treatment which factors could have an impact on the treatment result in general and on treatment success in particular. Treatment of an implant with peri-implantitis is often classed as successful if the following objectives are achieved:

  • Maximum probing depth of 5 mm and no bleeding on probing at a site with a probing depth of 5 mm or a maximum 4 mm probing depth, irrespective of bleeding on probing
  • No progressive peri-implant bone loss
Patient- and implant-related factors – what affects the outcome of treatment?
Patient- and implant-related factors – what affects the outcome of treatment?

A research group from Spain recently published a prospective case series with 74 patients and 107 implants, in which they investigated which patient-related and implant-related factors affected the result of non-surgical treatment of peri-implantitis (Vilarrasa et al. 2023). This study included patients who had at least one implant with peri-implantitis with at least 3 mm of peri-implant bone loss. The patients received the following treatment:

  • Oral hygiene instructions
  • Adjustment of the shape of the prosthetic restoration (if necessary)
  • Cleaning with ultrasound, curettes and air polishing
  • Prescription of antibiotics (metronidazole 500 mg, 3 times a day for 7 days)

After six months, the treatment success was assessed on the basis of the criteria listed above. Treatment success was only achieved with around every fourth implant, i.e. in only 25% of cases. This confirms the unfortunately often low chances of success of non-surgical treatment of peri-implantitis and therefore the need to work well within the team to be able to plan any surgical interventions carefully.

Let's come back to the original question: Which patient-related and implant-related factors had an impact on the result? Using the statistical evaluation as a basis, the following factors proved to be relevant as they reduced the chances of success of the treatment:

  • Patients with stage III or IV periodontitis
  • Patients with grade C periodontitis
  • Inadequate oral hygiene
  • Implants with a wide diameter
  • Smokers

Other factors, such as implant position, implant surface finish, type of prosthetic restoration (bridge versus single-tooth restoration) and method of securing (cemented versus screwed-on) had no significant impact on the result. While the parameters listed above may be ‘familiar faces’, the study also shows us that the prosthetic parameters, provided that the restoration is easy for the patient to clean, do not appear to have a major impact and therefore an implant in a cemented bridge solution should not necessarily have a worse outcome than a screwed-on single-tooth implant.


  1. Javi Vilarrasa, Maria Costanza Soldini, Ramón Pons, Cristina Valles, Gonzalo Blasi, Alberto Monje, José Nart. Outcome indicators of non‐surgical therapy of peri‐implantitis: a prospective case series analysis. Clinical Oral Investigations (2023) 27:3125–3138.