Still attached

May 1, 2000
Dental implants have changed the face of conventional dentistry by adding another dimension to treatment-planning options. However, as hygienists, these changes have evolved into a new phase of maintenance care for our implant patients and us. This article reviews basic implant knowledge and offers an overview of the current status of dental implant maintenance.

The maintenance of implant patients is as important as the surgical and restorative procedures.

Ann-Marie C. DePalma, RDH, BS

Dental implants have changed the face of conventional dentistry by adding another dimension to treatment-planning options. However, as hygienists, these changes have evolved into a new phase of maintenance care for our implant patients and us. This article reviews basic implant knowledge and offers an overview of the current status of dental implant maintenance.

In order to understand the maintenance component of implants, one must first understand the basics of implantology. Various styles and types of implants are on the market. Their use varies with the type of bone used with the implant and the type of prosthesis to be delivered, but several basic components are universal throughout implantology.

First is osseointegration, the "attachment" of bone to the implant surface as seen under the light microscope. In other words, it is inorganic material (implant) attaching to organic material (bone). Implants fail without stable, secure osseointegration.

Second, implants fail for two primary reasons and several secondary reasons. The primary reasons for failure are biomechanical overload and bacterial invasion. Biomechanical overload and the secondary reasons for failure are beyond the scope of this article, but bacterial invasion is important throughout hygiene protocols. As we know, more than 300 different types of bacteria are present in the mouth, yet only a small percentage of these are pathogenic to teeth. But the same forms of bacteria that are pathogenic to teeth can be detrimental to implants. Therefore, it is imperative to maintain good oral hygiene and have optimum periodontal health before proceeding with implant therapy.

Third, the epithelial attachments that surround implants differ from the attachments that surround teeth. Teeth are supported by periodontal ligament fibers that attach vertically to the tooth and bone. Implants do not have a periodontal ligament attachment or the vertical attachment, but do have a circular fiber attachment. These fibers also differ structurally at the histologic level.

This tissue/implant interface is known as the perimucosal seal. The perimucosal seal is the tissue barrier that prevents microorganisms and other inflammatory agents from the oral cavity from entering the tissues that surround the implant. It contains sulcular epithelium, and its presence is important for the longevity and success of the implant and prosthesis.

Therefore, any bacterial invasion can affect and destroy bone much more rapidly along the circular fiber configuration than along the vertical fibers. As a result, implants can show signs of plaque-induced tissue inflammation (peri-implant disease) or loss of supporting bone due to bacterial invasion (peri-implantitis).

As mentioned previously, different manufacturers have developed varying designs and configurations. But they are all basically variations to this general configuration:

- The "body" or "fixture" of the implant is the portion of the implant that will be surgically placed into bone. This fixture, in a root form endosseous implant, can be cylindrical (press fit) or screw type. The fixture usually needs a period of three to six months unloaded for osseointegration to occur (however, there are implants currently available which can be loaded as soon as eight weeks post-op).

- After the osseointegration phase is complete, an abutment is placed on the fixture. The abutment is used to support and/or retain the prosthesis to the implant fixture. Most often the abutment is screwed into the fixture, but it can be cemented.

- Finally, the prosthesis is either screwed or cemented onto the abutment.

Each implant manufacturer has a variety of components that can make up this "stack," but these are the primary components generally used.

The metal used for implants is titanium. Titanium is ossephilic (bone loving), has great strength (as strong as steel, but much lighter), is non-corroding and biocompatible, and is a poor electrical and heat conductor.

Most implants are titanium-based with a surface coating over a portion of the implant to allow for better osseointegration. These coatings can also chemically aid in bone growth. Some of these coatings include hydroxyapatite, titanium plasma spray, and acid-etched materials.

Titanium`s major disadvantage is that it scratches easily. This has a definitive effect on our hygiene protocols. We need to be aware of patients who have implants so that our maintenance procedures will not be detrimental to the implant or the prosthetic components. This becomes more critical with the newer techniques which can make implant restorations appear more tooth-like and more like traditional crown and bridge restorations.

Implant maintenance

Maintenance of the implant patient consists of two primary components: the patient`s own home-care techniques and our professional recall appointments. Maintenance of implant osseointegration is as important as achieving it. The best surgical and restorative techniques can be undone by inadequate or improper maintenance. Therefore, it is imperative for the hygienist to remain well-versed in the maintenance of the implant patient.

Maintenance can begin with the surgical placement of the implant. The hygienist should have some basic knowledge of the treatment objectives that the patient and dentist are following. This includes a basic understanding of the surgical procedures and restorative techniques that are used. Several continuing education courses can give the hygienist a good overview in these areas. If the hygienist is unaware of what the patient is experiencing through implant therapy, how can he or she provide effective home-care instruction?

Upon surgical placement of the implant, the patient will undergo a period of osseointegration. Given the implant system used, the implant may be completely submerged subgingivally, may be protruding above the gingival margin, or may be partially submerged. If completely submerged, no changes in routine home-care instructions are indicated.

If, however, the implant is partially or completely above the gingival margin, simple home-care techniques can then be prescribed. These can include brushing the metal with a soft toothbrush, rinsing with chlorhexidine, or dipping cotton-tipped applicators in chlorhexidine and applying to the area. If the patient has been a complete denture patient and has not been using any type of home care for a period of time, reintroduction to available products can be beneficial.

After the osseointegration is complete and the abutment and/or prosthesis are attached to the fixture, regular home-care maintenance procedures can be performed. A variety of factors can be used in determining products for home care. These include:

* Manual dexterity, motivations, and general medical and oral health

* Prosthetic restorative design and location

* Implant abutment angulation, length, and location

* Practitioner`s preferences

Traditional home-care techniques of modified Bass brushing techniques, the use of floss and floss threaders, and nylon-coated proxy brushes can be used. Several brands of floss currently available from manufacturers can be used specifically for implant patients. Manual, electric, and sonic toothbrushes can be used effectively with implant patients, given the patient`s dexterity and other considerations. Oral irrigators can be recommended if used at a low level and directed away from the tissue/implant junction, but the chance for improper use is high. End-tufted brushes and antimicrobial rinses are also beneficial.

Each patient`s situation at any given moment in implant therapy guides the clinician in determining appropriate products to recommend. These maintenance products and procedures can be altered at any given time if found to be ineffective. Successful home-care instructions should be individualized for each patient, and should be demonstrated as well as instructed. The patient should also be encouraged to set a daily routine. These techniques are also used on regular maintenance patients.

Recall protocol

The role of the hygienist in the maintenance of the implant patient is multifaceted. Not only do we need to educate the patient regarding daily home care, but we also must be effective in the techniques we use during the recall appointment. The successful recall appointment involves several components:

* Evaluation of the patient`s effectiveness of home-care techniques

* Evaluation of the tissues surrounding the implant

* Evaluation of the implant structure and prosthesis

* Thorough debridement of the implant and the natural dentition.

A thorough, systematic regular protocol is essential to the maintenance of the implant/prosthesis. Implants are susceptible to the same local factors of plaque, calculus, and enzymes as the natural dentition.

However, instrumentation around implants is different than around teeth. Due to the fact that titanium can scratch easily, stainless steel curettes should not be used along the abutment or the fixture. Several implant manufacturers have developed various types of plastic instruments. While the early plastic scalers were very bulky and did not scale effectively, current plastic resin scalers perform more like traditional scalers.

With the recent advent of abutments submerged below the gingival, it is not necessary to scale the fixture if little or no deposits are found on the abutment. However, if there is significant deposit, care must be demonstrated due to the fragile nature of the tissue fibers attached to the fixture. Sonic or ultrasonic scalers may also be used, but with caution, and only with specially designed tip covers. Care must be taken during instrumentation that the covers remain intact and that metal-to-metal contact does not occur. Mild prophy paste may be used to polish the prosthesis as necessary. If the titanium is scratched in any way, this can lead to greater plaque and calculus retention, and the possibility of peri-implantitis.

An important but controversial component of the recall appointment is probing the dental implant. Practitioners disagree as to whether implants should be routinely probed, but most agree that a plastic probe should be used.

However, increased probing depths may not be indicative of disease. Due to the type of fiber attachment and the type and length of the abutment, probing depths may be larger than those normally considered "healthy" in the natural dentition. If, for whatever reason, the implant fixture is surgically mounted - either buccally or lingually - so that the prosthesis could be placed in good occlusion, then a longer or angled abutment may be needed to achieve the natural occlusion. This would then result in a greater probing depth because of the length of the abutment. The hygienist needs to be aware of this when probing, noting that an increase in depth does not necessarily mean disease.

Also, the type of connective tissue fibers that attach to the implant can produce greater probing depths. A baseline probing depth should be recorded at the patient`s initial post-restorative maintenance visit, especially if the type of implant and abutment are unknown. This can give the hygienist a way of determining if detrimental changes are occurring at future recall visits.

Other components of a good implant recall appointment are radiographic evaluation, charting, mobility assessment, and restorative evaluations. Radiographs can be used to monitor osseous changes and should be taken at baseline when prosthetic loading occurs - at six-month intervals for the first year, and then every 18-24 months thereafter or as conditions warrant. Due to the nature of bone remodeling around implants, slight osseous changes may be noted. Bone loss down to the first thread of the implant fixture within the first year is considered normal, with slight variations in subsequent years. Anything greater is considered abnormal.

Each implant patient`s charts should be noted with a coding system. With the advent of new restorative techniques, implants are progressively becoming more like conventional dentistry. However, it is crucial for the hygienist to be aware of where an implant exists before proceeding with treatment. Placing a colored dot or label on the outside of the chart or making obvious notations in the clinical chart or in the practice`s computer software program can be "red flags" to alert the hygienist that this is an implant patient.

Mobility of the implant is also an area of concern. Due to the nature of osseointegration, any amount of movement of the implant fixture can be detrimental to the health of the implant. Sudden loss of osseointegration can occur. Therefore, as part of the recall appointment, both the restoration and the implant structures should be monitored for mobility. Often the screw connecting the abutment to the prosthesis can become loose or the screw access hole covering material may be dislodged. This is occurring less now with more cementations of prosthesis to abutments.

However, the internal screw component connecting the abutment to the fixture can also become loose. This is more detrimental and needs to be addressed quickly due to the micromotion that can occur along the implant stack.

A way of determining which mobility is present is by placing two mirror handles on either side of the prosthesis and pressing. If salivary percolation occurs (bubbling along the gingival margin), then the internal screw is loose. If there is no percolation, then only the external screw or cement is loose. This can also be confirmed radiographically. Loose internal screws will show a gap in the implant stack. Also at this time, the prosthesis can be evaluated for any signs of abnormal wear or other complications.

Implant dentistry has evolved tremendously in the past 30 years. It is constantly being updated and changed. The practicing hygienist needs to be educated regarding this ever-increasing area. Patients are always looking to hygienists for answers to numerous questions regarding the various aspects of dentistry. Implants are a treatment option that can offer the patient - and the hygienist - unlimited opportunities.

Ann-Marie C. DePalma, RDH, BS, is a 1978 graduate of the Forsyth School for Dental Hygienists. She is active in the Massachusetts Dental Hygienists` Association, having served in various positions. She can be reached at (781) 245-8811.

References available upon request.