The hygienist’s role in dental implants

March 21, 2012

Dental implants have been part of mainstream dentistry for several years. One of the keys to their long-term success is preventive maintenance. It is in this regard that the dental hygienist plays a central role in the long-term health and survival of dental implants.

Dental implants have been part of mainstream dentistry for several years. One of the keys to their long-term success is preventive maintenance. It is in this regard that the dental hygienist plays a central role in the long-term health and survival of dental implants.

In addition to the maintenance aspect of dental implants, the hygienist is typically the key figure in patient hygiene instruction. To properly understand his/her role in this field, the hygienist needs to have a detailed knowledge of the structure of the implant/restorative interface, as well as the local anatomy. In this article, I will review the five key factors hygienist need to understand. Although the examples used are basically for single-tooth restorations, the principles are applicable to all types of implant-supported restorations.

1. Anatomy

Having a clear understanding of the anatomy of the bone and tissue is central to peri-implant maintenance. Consideration of anatomy typically involves the periodontal biotype, which is an indication of the character and width of the bone and soft tissue.

The second consideration in anatomy is the position of the implant in three dimensions. Human teeth are typically positioned buccally in the alveolar process. This means the thinnest part of bone is on the buccal. Upon extraction, a portion of the alveolar process on the facial is lost. Although this can be controlled with ridge preservation and bone augmentation procedures, most implants have a lingual or palatal position. This means the restoration’s buccal profile is wider buccal-lingually than the most buccal position of the implant.

The third consideration in anatomy is the position of the implant with respect to the adjacent teeth.

2. How the crown is attached to the implant

There are typically two ways in which the restoration is attached to the implant. The most commonly used is the cemented restoration. The abutment is attached to the implant and in turn, the restoration is cemented to the abutment. It is important to debride the abutment crown interface without impinging on the possible biologic attachment to the abutment. Depending on the thickness of the periodontium, there may be an extended sulcus that requires regular maintenance. This is particularly evident in the thick periodontium. It is in this biotype that we are likely to see retained cement as a source of infection. In these cases the hygienist often recognizes the problem, which typically presents as acute inflammation and a purulent exudate.

The second approach of implant restoration attachment is with the screw-retained restoration. Although there is no cement involved, it is important to understand the exact position of the restorative implant junction as this is where most bacteria are likely to accumulate. 

3. Emergence profile

In anterior teeth as well as bicuspids, the diameter of the implant typically approximates the diameter of the restoration. Depending on the construction of the crown and the width of the available bone (ie. diameter of the implant), there can be a significant discrepancy between the shape of the crown and the shape of the implant. Rather than having a smooth transition in the contour of the restoration as it emerges from the tissue, we sometimes have a sharp widening of the emergence profile as we go from a circumferential implant platform to the natural shape of the teeth. In these cases, there can be an undercut at the level of the tissue where bacteria and debris can accumulate.

The emergence profile, in particular the emergence angle that the abutment or restoration will take throughout the tissue, will dictate the difficulty of maintenance. This is particularly important as platform switching for bone preservation has become a popular practice. The hygienist needs to understand the changes in diameter from the implant restorative platform to the free gingival margin to properly instrument and instruct.

4. Position of the margins with respect to the tissue

This also can be an indication of the probing depth and it varies throughout the circumference of the restoration. Ideally, the margins follow the same profile as the natural tooth with the facial and lingual margins more apically positioned than the interproximal margin. However, many restorations have the same occluso-apical position throughout the circumference. To know how far to instrument, the hygienist needs to be aware of the position of the margins. This also has implications when the implant is adjacent to natural teeth as the position of the margin can affect the health of the natural tooth attachment.

There are two areas of likely bacterial accumulation that need to be instrumented. These are the interface between the restoration and the abutment as well as the interface between the abutment and the implant. In the cemented crown, there are two possible openings. In the screwed in restoration, there is only one.

Help them make the right decision

Understanding peri-implant anatomy is a pre-requisite for proper maintenance around implants. Before undertaking the responsibility for implant maintenance, the hygienist should review the pertinent details of the implant restorative interface with the doctor. It is only with this understanding that the hygienist can properly serve his/her role in maintenance as well as instruction. Differences of opinion exist as to how much instrumentation should be done around implants. Armed with the information presented the hygienist can make an intelligent decision on the appropriate instrumentation.