Problems At Abutment Seating

Periodontal procedures are available to lay the groundwork for restorative and cosmetic dentistry, to improve function and the appearance of your patient’s smile.

A common problem arises when you come to seat the restorative abutment because of a disparity in size between the healing abutment and the final / restorative abutment.

The problem arises in part due to the gingival anatomy around implants with a well organised band of circumferential fibres in the connective tissue compartment.

This makes seating the abutment difficult and tissue blanching occurs (note 1). If not addressed then this can result in recession occurring as the tissues remodel.

This is overcome by severing or releasing these fibres to allow the abutment to be seated. The steps in doing so are outlined below.

You first need to anaesthetize on the labial & also into each of the papillae. Infiltrating the papillae rather than giving a palatal injection is important as it gives haemostasis as well making completion of the restorative phase – cementing the crown possible. (a.)

Anteriorally you start palatal to the crest of the papilla. (b.)

Posteriorally you can start in the mid interproximal. (c.)

You use a #15 or #15C blade

Laying the back of the blade against the healing abutment you push vertically down to crestal bone, then move the blade towards the adjacent tooth. It is a single motion – you do not need to re-capitulate. This minimizes tissue trauma and subsequent bleeding.

You can then place the abutment, torque & cement the implant
crown. (d.)

Click on the images to enlarge 

Other issues

The combination of intimate fit and hydraulic effect in seating the crown works against us. Intimate fit achieved by CAD/CAM or machined abutment preparation results in greater parallelism than we achieve as dentists with “direct” tooth preparation.

The gingival tissue anatomy is different around implants – there is a stronger circumferential fiber organisation but no “inserting” fibres like Sharpey’s fibres that exist in the periodontal ligament. This combination of factors can result in cement being pushed apically on seating during cementation.

Tip

Ask your technician to use a double layer of die spacer on the abutment before making the implant crown.

We suggest using Tempbond or one of the other lighter grade cements (Resin modified glass ionomer – 3M Espe) that allows retrievability and easier clean up. Take a check PA film after cementation to ensure that there is no cement left behind.

How much blanching is acceptable?

This is quite anecdotal and will vary from case to case. Our concern is blanching of the labial tissues when you do abutment connection or place a screw-retained crown (possibly a one-piece temporary crown).

Rule of thumb – if blanching is still present or not reducing after 5 minutes (particularly with a thin tissue biotype) then you need to consider releasing the circumferential fibres.

If you are placing a temporary crown you should consider altering the labial contours of the abutment/crown complex.