With accurate diagnosis, careful treatment planning, and patient compliance, overdentures have become mainstays of conservative prosthodontic treatment. Root retention offers a variety of benefits, including alveolar bone maintenance, better prosthesis support, proprioceptive feedback, esthetics, and psychological benefits.
Here's a case where Locator attachments from Zest Anchors were used to salvage an existing maxillary overdenture. They were chosen to treat the cuspids to provide retention and stability in addition to restoring the previous support function of the remaining roots. Locators can be used to attach to roots with or without a coping in a direct or indirect technique. This case will demonstrate a direct technique without a coping.
The patient presented with carious root structure around the amalgam overdenture abutments on the second bicuspid and two canines. The residual maxillary ridge mucosa was healthy. The patients was happy with the fit and esthetics of the existing denture, and he expressed a strong desire to keep his roots and avoid surgery.
 Figure 1 |
Decay was removed from the cuspid roots, exposing enough sound structure to proceed with treatment (Figures 1 & 2).
 Figure 2 |
The second bicuspid was not restorable and subsequently extracted. The panoramic radiograph demonstrated previous successful endodontic therapy and sufficient root structure in the bone (Figure 3).
 Figure 3 |
Root preparation
The next step was to prepare the root to receive the Locator post. The Locator Root Attachment Kit (Figure 4) contains a sized latch-type post bur to prepare the canal space (Figure 5).
 Figure 4 |
 Figure 5 |
At least 5 mm of gutta-percha should be left as an apical seal. The post may be shortened if necessary. The spot-faced bur was then used to create an internal dentinal seat for the Locator female post (Figure 6).
 Figure 6 |
If needed, 10°- or 20°-angle correction posts may be used to correct divergent roots. It is recommended by the manufacturer to parallel the path of insertion of the Locator attachments for root form prosthesis to less than 10° of divergence. Angle corrections for root-form attachment of Locator-retained prosthetic appliances can be easily accomplished using the various angles of the female Locator post. Nylon components can be quickly and easily removed using the Locator Tool if a change in retention strength is necessary.
PREPARATION FOR CEMENTATION
Before post cementation, Metal Primer II was applied to the serrated metal post portion to enhance bond strength to the dual-cure
G-Cem resin cement (Figure 7) The cement was placed in the clean, dry canal and the posts were seated using the black plastic alignment rods (Figure 8). The cement was light-cured, thus allowing quick removal of coronal excess (Figure 9).
 Figure 7 |
 Figure 8 |
 Figure 9 |
DIRECT PICK-UP
The metal housings containing the male nylon processing components were then placed onto the posts cemented into the cuspid roots. The intaglio surface of the denture was hollowed out in the cuspid areas to allow complete intraoral seating of the denture without interference from the bulk of the two housings. A small relief hole was made in the denture to allow for extrusion of excess resin (Figure 10).
 Figure 10 |
The superior portions of the metal housings were microetched and treated with the same metal primer to increase the bond strength of the metal housing to the luting resin (Figure 11). The housings, with included white spacer rings,were returned to the Locator females. A direct pick-up of the housings in the denture was accomplished using pink Triad® Gel as the luting agent. A thin layer of Triad Bonding Agent was applied to the acrylic of the denture in the hollowed out area and light cured for 10 seconds to ensure a strong bond between the composite Triad gel luting agent and the denture acrylic. The resin was light-cured through the denture intraorally and the process was repeated for the other attachment (Figures12 and 13).
 Figure 11 |
 Figure 12 |
 Figure 13 |
After the denture was adjusted and polished, the occlusion was verified (Figure 14). The Locator Tool was then used to remove both nylon processing components from the metal housings incorporated in the denture (Figure 15). Retentive nylon male components of various color-coded retentions can then be placed as dictated by the needs of the patient. The lightest-retention blue Locator retentive male, at 1.5 lbs, is generally recommended at delivery (Figure 16).
 Figure 14 |
 Figure 15 |
 Figure 16 |
After the rehabilitation of the maxillary canines, the patient was instructed in the proper care of his root attachments by using a daily fluoride gel and performing meticulous plaque control. Regular recall appointments were scheduled to check for patient compliance and appropriate tissue fit of the denture. Relines will be performed as needed to ensure proper functioning and longevity of the attachments in addition to promoting long-term health of the supporting mucosa.
The patient was extremely satisfied to have avoided extraction of his remaining cuspid roots and the ability to maintain his current denture. He was also pleased to gain the extra retention and stability from this treatment modality.