How to Prevent Peri-Implantitis With Elimination of Cotton Plugs or PTFE

Focus on peri-implantitis has increased in recent years, due to an escalation in reported incidence. This has not been due to growing case numbers, but to more frequent identification of this pathological process as practitioners come to understand the signs and symptoms.¹

Peri-implantitis is a pathological process that occurs at the bone surrounding dental implants and is characterized by inflammation of the soft and hard tissues adjacent to the implant, which leads to progressive loss of bone supporting the implant. It may appear as mucositis early in the life of an implant or many years after restoration of the implant, and may progress slowly or in an accelerated manner depending on the causative factor and the patient’s immune system.

Peri-implant disease is classified as either peri-implant mucositis or peri-implantitis. Peri-implant mucositis is classified as inflammation found only around the soft tissues adjacent to the implant, with no bone loss evident. Peri-implant mucositis is a precursor to peri-implantitis and may be successfully treated to prevent progression to peri-implantitis when identified early enough. With peri-implantitis, the gingival inflammation has progressed to the underlying bone, leading to deterioration of osseous support of the implant. Treatment of peri-implantitis typically requires surgical intervention to stop progression and repair the lost hard tissues.

The clinical conditions leading to the conversion from gingival inflammation to peri-implantitis are not completely understood.² Evidence suggests that progressive crestal bone loss around implants in the absence of clinical signs of soft-tissue inflammation is rare.2 Peri-implant mucositis is a relatively benign, reversible condition, yet can progress to peri-implantitis.^3,4 Some patients, particularly smokers or those with a history of chronic periodontitis or diabetes, are more susceptible to peri-implant diseases.⁵

So, where can bacteria originate before leading to peri-implant mucositis and potentially peri-implantitis? The oral cavity is filled with bacteria and other microorganisms. Historically the focus has been on poor home care as a major factor in peri-implant disease, but other sources of microorganisms in the oral cavity need to be considered. Research has demonstrated that bacteria in the oral biofilm can be harbored between the implant and the restorative parts connected to it at the implant platform.

The Implant Connection as a Potential Source of Bacteria

When implant abutments and other parts that connect to the implant at its platform are manufactured, large volumes of product are machined, and what is referred to as “slop” is designed into the process to allow for tolerance variables and product parts that fit. This is so that any abutment will seat into any implant when manufactured. The result is a microgap between the implant and abutment at the connector. This also pertains to the abutment screw that will thread into the channel in the implant (Figure 1). That microgap is not visible to the eye, but only under the scanning electronic microscope; however, it is large enough for bacteria that are much smaller to exist in the microgap. These bacteria then have the potential to percolate out, leading to inflammatory conditions in the surrounding gingival tissue and potentially spreading to the crestal bone.

A study reported microgap sizes ranging from 2 to 7 µm at the implant-abutment connector, whereas another reported a variation in microgap size ranging from 10 µm to 1.72 mm, which is wider than the bacteria found in the oral environment.⁶ Biofilm has an adhesive nature, sticking to all surfaces in the mouth including titanium and zirconia, from which implants are fabricated.

Additionally, micromovements during occlusal function can lead to wear at the implant connector,increasing the microgap sizes.⁷ This can lead to a pumping effect, pushing bacteria in the connector in and out of the connection and being a further source that may lead to gingival inflammation.

Sealing the Screw Access

Whether the restoration will be retained with a screw or be an abutment with overlaying cemented restoration, a screw is utilized to fixate something to the implant at the platform. A pliable material is required to not occlude the hex or square on the fixation screw so that it can be engaged to either remove the screw or tighten it when required. Traditionally, this was accomplished with a piece of a cotton pellet that in the case of a screw-retained restoration was then sealed at the crown’s surface with a composite resin.

A shift occurred some years ago to utilizing a piece of polytetrafluoroethylene (PTFE [plumbers’ tape]) to overcome the bacteria and odor noted when the composite was removed from over the plugging material or in the case of a cemented restoration when the abutment was exposed to access the screw. Studies have reported high levels of streptococci and fungi were found in those cotton pellets, with less noted when PTFE plugs were used.^8,9 But, being an inert material, PTFE does have the potential to allow bacterial biofilm to exist in those sealed areas. So, we can seal the area over the fixation screw, but with micromovements between the restoration and implant at the connector due to the microgap, how do we prevent bacteria from growing in those areas and prevent potential peri-implantitis?

Use of Silver

Silver nanoparticles have been demonstrated to be a potent and broad-spectrum antimicrobial agent. This has no cytotoxic effect on the metabolic activity of the host cells and is an effective broad-spectrum bactericidal agent, regardless of the antibiotic resistance of the bacteria.¹⁰ These particles are smaller than the microorganisms, diffusing into the pathological cells, rupturing their cell walls with no negative effect to the host’s cells.¹¹ Studies have reported that utilization at the implants connector that oral microbiological organisms are inactivated that could be found in the oral biofilm.¹² These silver particles do not have a life span and their antibacterial properties remain as long as the particles remain within the area.

SilverPlug

SilverPlug® (SilverPlugUSA) was developed utilizing silver zeolite, a naturally occurring substance, in a pliable polymer material to allow adaptation to the area over the fixation screw, adapting to the geometry of the space as it is placed (Figure 2). The material has been utilized in the European Union for more than 10 years and has certification as Class IIA material with medical device regulation. SilverPlugwas granted FDA approval in 2022. The SilverPlug does not release silver particles and kills microorganisms that come into contact with it. The silver particles are incorporated into the silver zeolite contained into the medical polymer and do not migrate away from the plug material. Thus, with a dramatic reduction of bacteria present in the area in and around the abutment/implant platform gaps and screw access tunnel, no odor is noted that would be commonly reported when cotton pellets or PTFE are used.

Placement when a screw-retained restoration is being used consists of carrying the SilverPlug to the screw access opening and determining the width needed at that site (Figure 3). Length is then determined that will allow 2 mm of composite to be placed over it and be flush with the restoration’s surface; the plug is cut with scissors (Figure 4). The piece of cut plug is then carried to the access hole with an explorer or perio probe and inserted into the access hole (Figure 5). Cotton pliers can be utilized to hold the plug in the restoration as the explorer/probe is withdrawn. A restorative plugger can be utilized to push the SilverPlug into the access space until it is 2 mm apical to the restoration’s surface (Figure 6).

As the material is pliable, excess can be removed with the edges of the plugger or a diamond bur in a highspeed handpiece so that no material is in contact with the access opening circumferentially in that 2-mm area apical to the restoration’s surface. Similarly, if a cemented restoration is being utilized, the SilverPlug is placed to the superior aspect of the abutment (Figure 7).

Should the fixation screw need to be accessed, removal of the SilverPlug is easy. After exposing the SilverPlug following removal of the overlaying composite or—in the case of a cemented restoration—removal of the restoration, the plug is ready to remove to access the screw. As the material remains pliable, an instrument is inserted into the SilverPlug and it is pulled out of the access area (Figure 8).

If the instrument is having trouble removing the plug, a large (size 45 or larger) endodontic file can be threaded into the plug and pulled out of the area. Removal is easier than removal of a cotton pellet that may leave fibers in the area over the fixation screw’s head or PTFE. The removed SilverPlug can be reused on that same patient should the screw need retightening, or if the restoration is being reinserted at the same appointment.

Figure 1

A microgap is visible between the abutment and implant (top) and between the fixation screw and the threaded channel in the implant (bottom). (Reprinted with permission from the authors of the article, Lopes PA, Carreiro AF, Nascimento RM, Vahey BR, Henriques B, Souza JC. Physicochemical and microscopic characterization of implant-abutment joints. Eur J Dent. 2018;12(1):100-104.)

Figure 2

SilverPlug screw access opening antibacterial sealer.

Figure 3

A SilverPlug is removed from the package and inserted into the screw access opening that will be sealed.

Figure 4

Following determination of the width and length of SilverPlug needed for that screw access opening, the plug is cut with scissors.

Figure 5

The piece of SilverPlug is carried to the screw access opening (left) and inserted, held in place with cotton pliers (middle), and the carrier instrument is withdrawn, leaving the plug in the implant restoration (right).

Figure 6

A restorative plugger is utilized to compress the SilverPlug into the area above the fixation screw (left and middle); when done, space is left for placement of composite over the plug to finish sealing the screw access opening (right).

Figure 7

Placement of SilverPlug in an abutment prior to cementation of the implant crown on the abutment.

Figure 8

To remove the SilverPlug to access the implant screw, the composite covering the access opening is removed with a bur. An instrument is inserted into the plug (left and middle) and the SilverPlug is pulled out of the access (right).

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Conclusion

Oral biofilm has a strong connection with peri-implantitis, and those bacteria can be present between the implant and restoration at the connector or over the fixation screw. Utilization of a material that has antibacterial properties, which are present with nanosilver, aids in prevention of active microorganisms in those areas between the implant and restoration that are not accessible with home care. SilverPlug is an easy-to-use material to fill the area over the fixation screw and provide long-term prevention of the issues that contribute to peri-implantitis without affecting host tissues or their normal functions. Its pliable nature allows retrieval should the fixation screw need to be accessed.

Clinical images courtesy of the authors.

References

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