I’m missing a tooth! Now what? – Part IV (Dental Implants)
The final option to replacing a missing tooth is to get a dental implant.
A dental implant is, essentially, a titanium screw (some are made out of zirconium or a mix of titanium and zirconium). It is meant to replace the root or roots of the missing tooth. It is, in my opinion, the best option available to replacing missing teeth. They can be used to replace a single missing tooth, to support a bridge, or to provide increased retention for a removable denture. They have a very high success rate of approximately 92-96% (depends on the area of the mouth that the implant is placed). Getting an implant is usually a longer process, compared to the bridge or partial denture, but it is well worth the wait.
The implant is composed of several parts. For an implant crown, or bridge, you have the implant, an abutment (the intermediary piece) and the crown. The implant is the part that is placed in the bone and replaces the missing tooth root. Once the implant has integrated with the bone, it is ready to be restored. You can get 2 kinds of crowns on top of that implant. You can get a “cement-retained crown” or you can get a “screw-retained crown”. The cement-retained crown is very similar to the crowns people get on natural teeth. First, a part called an “abutment” is placed on top of the implant. This is the intermediate piece that the crown will sit on. After delivering the abutment, the crown is “cemented” on top, just as a conventional crown is cemented on top of a tooth. The screw-retained crown is a crown where the abutment and crown are made as one piece. There is a hole on the top of the crown where a screw is placed to screw down the crown into the implant. After torquing the screw down, a tooth-colored filling is placed in the hole. The difference between the 2 crowns is that the cement-retained crown is a little bit more esthetic. However, if you ever have an issue with the crown, it may have to be cut off, in which case new moulds will have to be made in order to make a new crown.
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If there is an issue with the screw-retained crown, the dentist can just go in and unscrew the crown, correct the problem, and then screw the crown back into place. It is retrievable. The downside is that, sometimes, the screw access hole can be seen even with a tooth-colored filling covering it. It doesn’t matter on upper teeth because the hole cannot be seen, but they can potentially be visible on lower teeth. The screw-retained crown is also dependent on the position of the dental implant. If the implant is not placed close to the center of the proposed crown, then a screw-retained crown may not be an option. There is also a downside with cementing the crowns in place, in that sometimes the cement may seep down towards the implant fixture. If cement is not completely removed, it can lead to bone loss around the implant, and ultimately the loss of the implant itself. There are many things that can be done to minimize this risk, but having a screw-retained crown eliminates that risk completely. If given a choice, I recommend getting a screw-retained crown, mostly due to it’s retrievability.
How is replacing a single missing tooth better than getting a bridge or removable partial denture? Well, a dental implant replacing a missing tooth is better than a removable partial denture because implants are fixed and do not come in and out. They are better than a bridge because an implant is a single tooth and not 3 teeth splinted together. Therefore, you are able to floss around an implant crown as you would all the other teeth in your mouth, as opposed to having to thread floss under the dummy tooth like you would have to do with a bridge. The implant and the crown placed on an implant are all artificial. There is no natural tooth structure supporting it like you have with a bridge or removable partial denture. Therefore, you don’t have the risk of getting cavities on them. Getting a cavity on a tooth supporting a bridge typically requires having to replace the bridge with a new one. Getting a cavity on a tooth holding a partial denture in place would require a filling, at the very least, which could change the shape of that tooth and the way it holds a partial denture in place. However, just like natural teeth, you can still get bone loss around an implant. So oral hygiene is still very important. But as I mentioned earlier, oral hygiene is easier to maintain because of the ability to floss around an implant “normally”.
There are usually 2 reasons for getting an implant-retained bridge. These are treatment planned when the empty space is too long for a traditional bridge, which means only 2 options are available to these patients; a removable partial denture or implants. The second reason is if a the patient is missing posterior teeth and there isn’t a tooth in back to hold a traditional bridge in place. Getting an implant to replace every missing tooth is unnecessary, but up to the patient. If there are any financial constraints, or if additional surgery or grafts are needed for 1 spot, then an implant-retained bridge is a good option. It allows for a shorter span bridge to be made; essentially, a empty space is about 2 teeth shorter when utilizing implants. Again, the bridge is fixed and does not come in and out like a partial denture. However, it is still a bridge, which requires a little more effort to floss under it.
Patients who are missing all their teeth in an arch, and want to have something fixed, will usually get implant-retained bridges as opposed to an implant for every single missing tooth.
Implants can also be utilized to help retain a removable partial denture in place, or a complete denture. In regards to a partial denture, an implant would be placed next to a tooth that would normally be used to hold the partial denture in place. A clip is placed on the implant, so the partial denture “clips” on top of it. This eliminates the need for clasps around the tooth (which could be unsightly if made in metal and is visible), as well as takes the load off of the supporting teeth as well. Not placing the partial denture on natural teeth gives these teeth a longer life span because they aren’t taking a lot of torque from the partial denture.
Similarly, implants are utilized with a complete denture to provide more retention. These are also typically used with clips. Lower complete dentures are notorious for being loose. Unlike the upper complete denture, where you have the roof of the mouth to help attain retention/suction, the lower jaw is horseshoe-shaped and has the tongue and cheek moving around, making the denture more prone to becoming loose. It is not a requirement, but a highly recommended treatment option for the lower jaw is to get 2 implants, minimum, which clip onto the complete denture. This provides the retention that many patients wish their conventional dentures had. It also provides more mental security, knowing that the denture isn’t going to fly out of the patient’s mouth as they’re talking or laughing. The quality of life improves significantly with these patients. The upper jaw usually requires a minimum of 4 implants, and that is due to the quality of the bone on the upper jaw.
Another option for a patient who is missing all their teeth in an arch (or both arches), is what is known as hybrid dentures. Some may know them as All-on-4 hybrids, or “teeth-in-a-day” hybrids. There are several variations, but they all work on the same principle. A hybrid denture is basically a denture that is screwed into the implants (as opposed to being held in with clips). It is, technically, removable, but only by the dentist. So, to the patient, the prosthesis is a fixed restoration (does not come in and out), and is made from the same material used to make conventional dentures (nowadays, complete zirconium hybrids are available as well). The sides of the dentures that go over the jaw are eliminated, so the hybrid is a lot narrower and much more comfortable. These are placed on 4-6 implants. As mentioned earlier, in regards to dentures with clips, the lower jaw requires 2 implants and the upper jaw requires 4 implants. By adding 2 more implants on the lower jaw, or none on the upper, you are able to transition into a hybrid denture. The cost is significantly more, but you are going from a removable prosthesis to a permanent/fixed one. There is a huge difference and those who “upgraded” their existing dentures have commented at what a big difference it has made. These patients have a greater sense of confidence with the hybrids, better ability to chew foods, and the luxury of NOT having to take their dentures out at night.
As you can see, implants have opened up the treatment possibilities for patients. It can get overwhelming choosing between all the options, but that’s a good thing. There are options for patients in all types of situations. For example, a patient who only had a removable partial denture as an option, now has the option to get something permanent. That patient can get an implant-retained bridge, or an implant to replace each missing tooth. If that patient cannot afford the permanent option, then an implant can make a partial denture much more secure and esthetic. Or the patient who comes in with several sets of complete dentures, all of which are loose or ill-fitting, now has the option to get something fixed and something that doesn’t come in and out. These patient’s have their quality of life turned completely around for the better.
In fact, with the popularity of implants today, more and more insurance companies are starting to cover portions of the implant crown or bridge, as well as the surgeries themselves. It wasn’t long ago when insurance companies would not cover any portion of implants because they would just say to get a bridge or partial denture. That is no longer the case. Implants have made a great difference in our field and in the lives of many patients.