This technique is described here because it is not typically found in many popular dental implant texts. The technique was developed by Dr. Gustav Dahl in the 1940’s. It is worth studying for those who desire a more complete understanding of implant dentistry. Photographs may be seen in various sections her on dental implants or visit us at our NYC dental implants office.
Intramucosal implant snapinserts are mushroom-shaped titanium projections which are attached with cold cure acrylic to the palatal side of a removable full or partial denture. They can only be used in the maxilla because the snapinserts require significant thickness of palatal attached gingiva receptor sites. The resultant connective tissue encapsulation around the mushroom-shaped insert heads result in mechanical retention of the prosthesis. The divergent paths of insertion lead to a secondary mode of retention and stability.
Snapinserts are used for additional security and retention with properly fitting and well constructed dentures, which have already been worn and adjusted. Patients should have a complete opposing occlusion. Palatal tissues should be firm and healthy.
Site selection for each insert is determined on the palatal side of the denture after verifying there are not palatal soft tissue contraindications. An acrylic receptor site bur is used to prepare sites within the denture for placement and attachment of the 12-14 insert bases. One row of three to four inserts are placed on the crest of the ridge, from the canine to the tuberosity. Another row of three inserts are placed along the junction of the palate and the alveolar ridge in a staggered fashion. The perimeter around each prepared insert base location is coated with dye from a purple denture transfer stick.
The patient’s palate is dried with gauze and is then instructed to close hard with the denture in place. The dye around each base site provide exact transfer of crest and palatal slope sites. Twelve to fourteen circles representing the snapinsert locations in the denture should be outlined in purple on the patient’s palate. A few drops of a local anesthetic with 1:100,000 epinephrine can be injected into each site.
A tissue receptor site bur is used at right angles to prepare a tissue channel in the center of each tissue site. The sites should be chosen where there is thick underlying tissue. If the palatal tissue is too thin at any given implant receptor site, the patient will experience pain when chewing or occluding because the head of the implant will push through the gingiva into crestal bone. That particular implant can be removed from the denture without loss of retention.
A tissue undercut bur is used to create an undercut in the tissues at the top of each insert channel. This undercut corresponds to the head of each insert. This bur is rotated only AFTER it is placed deeply into the tissue receptor site. This will create a female mushroom-shaped tissue receptor site that will retain the male mushroom-shaped implant.
An acrylic trim bur may be used to remove residual cold cure acrylic after it has hardened around the snapinserts in the denture. A small round bur is also helpful.
If the clinician finds that after putting the snapinserts into the denture they are unable to reseat the denture properly they should examine the path of draw of the snapinserts. Some divergence of the snapinserts between those on the ridge crest and those on the palatal junction is desired for maximum retention but if it is too great it will keep the denture from reseating. The clinician should remove the offending snapinsert and adjust the angulation before replacing it.
The patient should try to keep their teeth closed as much as possible for the next several weeks after the snapinserts are placed and to avoid chewing hard food. They should be on Peridex mouth rinse and can swish mouth rinse under the their denture to clean under it. They can also direct an oral irrigator under the denture to clean it. They should not remove the denture under any circumstances. It takes between three to six weeks for the palatal epithelium and connective tissue to properly heal around snapinsert heads so it is essential for both the clinician and patient to refrain from removing the denture because this will tear the newly formed epithelium and connective tissue. The patient should experience little postoperative pain.
The palate of the denture may be removed after two months if the patient desires. The clinician should attempt to minimize the frequency of removal of the snapinsert retained denture because this will adversely affect retention. The connective tissue in which the snapinserts are retained are torn each time the denture is removed.
Snapinserts typically come in two sizes with corresponding burs. It is recommended that the clinician first try this procedure with the smaller snapinserts because if there is inadequate retention around any given snapinsert the clinician may remove that one and prepare both the tissue and the denture with a larger one.
Some clinicians perform this procedure using trial snapinserts which allow nonfunctional healing analogous to two stage endosteal screws but this is usually not necessary. This technique involves placement of trial snap inserts into the tissue receptor sites without them being attached to the palatal side of the denture. The tissue is allowed to heal for several weeks before the trial snapinserts are removed and the regular snapinserts are attached to the denture.
The trial snapinserts have very thin metal bases which should be flush with the tissue when properly seated. The prepared base receptor sites in the prosthesis are then filled in with a soft tissue conditioner. A denture adhesive is applied to the maxillary prosthesis and inserted over the trial snapinserts.
In six weeks the snapinsert receptor sites are cleaned and the tissue conditioner is removed. The final snapinserts are attached to the previously prepared base site locations with cold cure acrylic resin. Local anesthetic is often not needed during this second appointment. The prosthesis is then placed into the mouth, and the final snapinserts should go into the healed tissue receptor sites. The occlusion and periphery is checked to make sure that the prosthesis is completely seated and stabile.
The intramucosal implant snapinsert denture can provide significant mechanical retention in the maxilla and should be considered a viable treatment option. It is relatively simple, quick, minimally invasive and easily reversible.
To see photographs of this technique click on “Dental Photos” at the top of this page and then click on ‘Implants, Intramucosal.’ There are hundreds of photographs in this section.