What are implant retained dentures or a locator denture?

Implant retained dentures are a type of overdenture that you can take in and out to clean and attaches to dental implants. It differs from the bar overdenture in that it gets support from tissue and typically the implants attach directly to the denture instead of to an intermediary bar. We will use the terms locator denture, implant retained denture, implant and tissue supported denture or overdenture throughout this post but they are all basically the same thing.

The implant retained overdenture or implant and tissue supported overdenture

The implant and tissue supported overdenture is a patient removable prosthesis that gets support from both dental implants and patient tissue. We prefer the term implant retained denture, as the denture is retained with some sort of attachment or stud on the implants.  The most common attachment is the locator and thus the term locator denture. This option requires fewer implants than any other option outside of a traditional denture.  Ensure if do use a bar with clips only one as multiple will inadvertently creates a supported prosthesis, instead of a retained.

The locator denture is common for the lower jaw. The best plan is either 2 implants with a bar and clip OR 2 individual implants and a denture with lateral throat form.

Some reinforce the acrylic with metal mesh to reduce acrylic fractures.

Reference

How many implants do we need and where should they be?

There should be 2 implants in the mandible and 4 in the maxilla. That can vary depending on many factors. Some research shows a single implant in the midline works effectively in the mandible. Coutinho JPD 2022.

Best location for the 2 implants in the mandible is in the lateral incisor area with short attachments according to Hong JOMI 2012.

For the maxilla 4 is often what we consider the minimum with no palatal coverage but full tuberosity coverage. JOMI 2007 Cavallaro Tarnow

Implant retained denture dental code = Locator denture dental code

This would be a locator or ERA retained denture.  These would be dentures that are retained by implants (actually some type of abutments), but are supported by tissue as well as the implants.

D6191 and D6192 are for semi-precision attachments.  The D6191 is for the semi-precision abutment on the implant body, in most cases this is the male portion. D6192 is for the semi-precision attachment that is in the removable prosthesis, which in most cases is the female portion. D5862 is the dental code to use if you are placing both the male and female component. Therefore for most cases this is the code you should use.

D5110 or D5120 denture might be easier to use but D5863 or D5865 Complete Overdenture is the correct code.

Codes D6110 and D6111 are for implant supported removable denture. Supported means NO tissue support, retained means some tissue support.  Most locator dentures are implant retained. Therefore unless you have 4 locators and the denture is being supported entirely by those 4 locators and not touching the tissue, this code is not correct.

Dental codes to replace locator attachments.

If you are either doing the initial luting or replacing the semi-precision attachment to the removable prosthesis then the dental code is D6192.  If you are replacing or placing for the first time the component of the semi-precision attachment that attaches to the implant body then the code is D6191. For the locator system this means placing the female portion is code D6192 and placing the male portion is code D6191. Dental code D5862 is very similar but covers both the male and female portion. It is for a precision attachment though, which locator is not, and is more for fixed work.

Dental code to replace plastic inserts in the locator.

D5867 is the dental code for replacement of replaceable part of a semi-precision attachment (male or female component). You can use this code for each replaceable part. For the locator this can be the plastic insert but to us it seems like the ideal code does not exist. Dental code D6091 seems to be the same but mentions the phrase implant/abutment supported prosthesis. So perhaps this is only for supported prosthesis vs the first code if for retained prosthesis.

Parts for a locator denture

This insert from Zest has all the information you need.

Treatment planning of the locator denture

Treatment planning of implant retained dentures is very similar to dentures and fixed detachable provisionals.

How do we measure vertical space for a locator denture?

Minimum requirement vertically is about 10mm with an ideal breakdown of 2mm for tissue, 2mm for denture acrylic base, 3mm for denture teeth, and 3.35mm for a locator.  For horizontal space constraints a Micro-ERA is 4.43mm so 8mm total is minimum, that leaves 2mm acrylic both sides. For a locator dentures you need about 9mm vertical and horizontal, but would like to see 10-12mm Lee 2006 JPD Sadowsky 2007 JPD

To measure the space available we have 3 main options

1. Make radiographic template (code 6190) and have them wear during CBCT
2. Measure existing/new denture or area with boley gauge or alma gauge.
3. Matrix capture of denture teeth, if not doing CBCT then this is best method.

CBCT option for space measurement of implant retained dentures.

This is a double scan technique.  One in which they are first scanned wearing the prosthesis and then the prosthesis is scanned by itself.

1. If patient is edentulous then make a duplicate of the finished temporary prosthesis with to wear as a radiographic template.
2. If patient has some teeth remaining do same thing, just remove the teeth that are still present from the duplicated finished temporary prosthesis
3. To make the radiographic template use 1:3 ratio barium sulfate powder (Hypaque Sodium by Amersham Health) OR
4. #6 round but to 1/2 depth around the lingual flange and fill with gp and polish off with rubber OR
5. Add radioopaque glass beads
6. Can mark attached tissue like seen in A Technique to Identify Attached Gingiva During Virtual Implant Planning
7. Patient wears during CBCT and besides reading bone levels can measure space available.

Matrix option for space measurement of the implant retained denture.

1. Once have approved wax baseplates can just remove from mounted models and measure.
2. There is several much more complex, JPD Aug 10 Ahuja, ways to do this. However, these methods don’t seem to be a whole lot more informative.

Locator denture fabrication procedure in a step by step format

Steps for the initial impression for the implant retained overdenture

1. Measure depth from implant platform to most coronal aspect of surrounding gingival tissue for depth of the locators.
2. Take alginate impression for custom tray.

Steps for the final impressions for the locator denture

1. Seat locator abutments to specified torque.
2. Place implant impression copings.
3. Clear thermoplastic tray by Massad or custom tray.
4. Paint tray with PVS adhesive.
5. Rigid PVS on palate, tissue areas, and directly over implant copings to act as stops. This is the Massad technique.
6. Trim most away most material except for solid stops on palate, tissue both sides, and on copings.  Leave just enough for positive seat of copings, do not come up sides.
7. Med PVS on periphery and light inside border mold.
8. Ask for processed denture base with metal subframe mesh support (probably? some say rather no and let acrylic break before implant does) with holes to pick up locators exactly. Most dentists to not ask for the final denture base at this step and we don’t either.
9. Also want wax rim with central SR Phonares set in wax.
10. Follow denture thread instructions from here.

Steps if picking up the female housings intra-orally.

1. Note – Some like to have the patient wear the denture for 48 hours to let it settle in and then adjust the intaglio before picking up the locators. That’s a nice idea but probably just gives a clinically unnoticeable better fit.
2. Place locator block out spacer ring and then titanium cap with black processing male (1 at a time? 2 at a time?) Just want to avoid locking it on like seen below.
3. Ensure locators with metal housing not hitting any acrylic.
4. GC fit check or some sort of fit checking material, we prefer whatever you use for bite reg but not the super hard PVS.
5. Adjust as needed and then place undercuts with #8 bur
6. Place vent hole to palatal or lingual
7. Refine occlusion now
8. Adhesive painted on denture area if your pickup material requires.
9. Petroleum jelly in areas don’t want maybe
10. Block out undercuts on implant (if any) with silicone like fit check or Fit Test C&B VOCO
11. Place resin in hole and seat denture and let self cure or LC if can.
12. Have the patient feel their masseter with their hands as they close and then clench and repeat until they can tell when the muscle is starting to clench.  Tell them you want them to close but not clench at all when doing your reline.
13. Remove and fill small voids with LC resin
14. Remove processing male insert and place appropriate strength

If a locator denture gets acrylic or pick up material into undercuts the denture can be impossible to remove. Here is an example of what has to happen. The lab can repair these so although it is not pleasant, it’s not the end of the world. What we do is have the patient do home with it in; sometimes they can break it loose from eating and chewing. Then come back the next day or soon and cut it out.

Implant retained denture loading and other instructions

Early loading of the implant overdenture is anytime we load between 48 hours and 3 months. Loading lower unsplinted implants at 1 week has same results as at 6 weeks with 14mm implants and a flapless surgery. While still healing recommend a soft diet and removal at night with thorough oral hygiene instructions. Should fabricate a night guard for removable overdentures in order to protect abutments from any para-functional activity.

Pardal-Pelaez JPD 2021 meta-analysis finds the immediate load leads to more implants lost and more bone loss than delayed load.