Plasma of Argon Cleaning on Implant Abutments: 5-year Results of a Randomized Clinical Trial

Effect of Plasma of Argon Cleaning on Implant Abutments in Patients With a History of Periodontal Disease and Thin Biotype: Five Years Post-loading Results of a Randomized Controlled Trial

Contamination of implant abutments could potentially influence the peri-implant tissue inflammatory response. The aim of the present study was to assess the radiographic bone changes around customized, platform switched, abutments placed according to the "one-abutment-one-time" protocol, with and without plasma of argon cleaning treatment.

After technical procedures, presence of contaminants (mostly Titanium wear micro-particles, Carbon and Aluminum traces due to lubricant used during customization) on the whole abutment surface, the internal connection and the screw can be found, even after the usually cleaning steps (steaming). Such debris, present at titanium/connective-bone tissues interface (gingival portion of the abutment), could directly or indirectly deleteriously influence the inflammatory response on the peri-implant tissues. Plasma of Argon cleaning treatment was demonstrated to have a double effect on titanium abutments: removal of pollutions following customization and increase of cell adhesion. Additionally, Plasma of Argon demonstrated very potent anti-biofilm activity. This prospective, match paired, triple-blinded randomized controlled trial was aimed to test if plasma treatment of customized abutments can affect radiographic peri-implant marginal bone level changes after 5 years of prosthetic loading.

Control group: dental implant abutments underwent cleaning by steam (VAP 1, Zhermark, Cologne, Germany), performed for 5 seconds at 4 megapascal (MPa).

Test group: dental implant underwent argon plasma treatment in a plasma reactor (Diener Electronic, Jettingen, Germany). The treatment conditions were 75 W of power and 1 bar of pressure for 12 minutes.

An implant was considered a failure if it presented any mobility, assessed by tapping or rocking the implant head with the metallic handles of two instruments, and/or any signs of radiolucency, progressive marginal bone loss or infection, and any mechanical complications (e.g. implant fracture) rendering the implant unusable, though still mechanically stable in the bone. This was evaluated on an intraoral radiograph taken with a paralleling technique strictly perpendicular to the implant-bone interface. The implant stability was assessed at initial loading and following 3 years of application, with the prostheses removed. A prosthesis was considered a failure if it needed to be replaced by an alternative prosthesis.

Complications: any biological (pain, swelling, suppuration, etc) and/or mechanical complications (fracture of the framework and/or the veneering material, screw loosening, etc) were considered.

At the time of loading with the provisional crown (T0), periapical standardized digital or analogical radiographs were taken in order to control the perfect adaptation of the abutment on the implant and control peri-implant bone level. The customized film holder was made using an hard silicone on the bite of film holders (Rinn XCP; Dentsply Rinn, Elgin, IL, USA) and the parallel technique was used. Radiographs were also taken at 12 (T1), 24 (T2), 48 (T4), and 60 months (T5) after the final restoration delivery, to evaluate marginal bone level changes.

Esthetic Parameters Measured as the Changes in Mesial and Distal Papilla Height (PH) and Buccal Peri-implant Mucosa Changes at the Zenith (REC), Expressed in mm.

A customized millimeter tubular support (stent) was placed temporarily around each dental implant. For each site, mesial and distal soft tissue dimensions (papilla height, PH), and buccal peri-implant mucosa dimension at the zenith (REC) were measured, and reported in millimeters. Two measurements were recorded. The first at definitive crown delivery (baseline), and the second at the 5 years follow-up examination. Changes in PH and REC were reported in millimeters as the difference between values recorded at the 5-year follow-up and the baseline. The full procedure was published in: Canullo L, Iurlaro G, Iannello G. Double-blind randomized controlled trial study on post-extraction immediately restored implants using the switching platform concept: soft tissue response. Preliminary report. Clinical Oral Implants Research [Internet]. 2009 Apr;20(4):414-20.

Modified Plaque Index (mPI) was evaluated as the amount of plaque at the cervical part of the implant-supported crown, scored by running a probe along the implant-supported crown surface. Measured as Yes or Not.

Inclusion Criteria: Patients aged 18 years or older, previously treated for periodontal disease according to a comprehensive treatment strategy,25 requiring a single implant-supported restoration in the anterior maxilla or premolar region with the presence of mesial and distal tooth. Bone crest allowing the insertion of a 4 mm platform implant without further bone augmentation procedures and with thin (≤ 1 mm) gingival biotype, measured by previously reported protocol. Exclusion Criteria: no relevant medical conditions; non-smoker or smoking ≤ 10 cigarettes/day; plaque Index and bleeding on probing ≤ 25 %; impossibility of follow-up for 5 years after prosthetic loading; pregnant and lactating patients; patients with a history of bisphosphonate therapy; presence of sites with acute infections.

Canullo L, Penarrocha D, Clementini M, Iannello G, Micarelli C. Impact of plasma of argon cleaning treatment on implant abutments in patients with a history of periodontal disease and thin biotype: radiographic results at 24-month follow-up of a RCT. Clin Oral Implants Res. 2015;26(1):8-14. doi: 10.1111/clr.12290. Epub 2013 Nov 6.