A Primer on Dental Implants and the Controversy over Titanium Versus Zirconia
Replacement of lost teeth with dental implants has been around for many years. Believe it or not, dental implants have been found that are 4000 years old! These were made of bamboo. The first metal implant was found in a two-thousand-year-old Egyptian King. Experiments with different materials continued until the 1950s, when Dr. Brånemark discovered that titanium implants could let bone fuse to it, causing it to be strong and durable. As a result, most dental implants are made of titanium today, and they are just as durable as natural teeth. Zirconia implants are now in use, but their popularity is limited. Local surgeons who place them are more difficult to find. This post will discuss implants and the difference between titanium and zirconia.
What Is an Implant?
Implants are artificial roots that generally come in the shape of a screw. The implant can only be placed where there is adequate bone; otherwise, it will come loose. A special dental CAT scan determines bone strength and quality, called a cone beam or CBCT. Once the bone hardens around the implant, a tooth can be attached. The bone can take over four months to heal before the tooth can be placed, but in some instances, it can be done immediately, but the risk of failure increases.
How Soon Can Implants Be Placed After a Tooth is Pulled?
As I mentioned, it is best to have the tooth out first and wait. It is common practice to place special minerals in the extraction site to ensure that the new bone growth where the root was is large and strong. The process is called site preservation or bone graft. I'm not too fond of the term bone graft because the body produces bone while growing into the mineral. Since we are growing bone, the term bone graft is misleading and somewhat inaccurate. The healing usually takes about four months. So, the implant placement may not happen for a while after an extraction. Lastly, once a tooth comes out, the bone will shrink over time, making implant placement more challenging as time elapses. In this situation, a bone graft is needed, like the technique I just discussed. Additionally, sinuses grow into areas where upper teeth have been removed. When a bone graft is done in a sinus, a common procedure, it is called a sinus lift.
How Soon Can a Tooth be Placed on an Implant?
It is best to wait for the bone to solidify around the implant. Therefore, several months must pass until the implant is ready for loading. As a result, the implant is sometimes left completely under the gums where it can't be seen. Another quick procedure is needed to remove a small circle of gums, called a second-stage or stage II surgery. After the implant is exposed, a short screw called a healing cap is placed. Titanium implants all come with internal threads for retention screw placement. Loading refers to the process of placing a tooth upon the implant. In the case of single tooth replacement, the tooth is referred to as a crown. Sometimes the implant receives its healing cap immediately, saving the exposure step.
How is a Crown Fitted to an Implant?
Two approaches can be utilized. The traditional way is to take an impression of the healing cap. Sometimes the healing cap is temporarily replaced with a longer impression abutment for more accuracy. The abutment is directly pulled out by the impression, where it becomes embedded or unscrewed and placed back in the impression. The healing cap is replaced immediately. The second way is to use a scanner instead of taking an impression. I prefer this method. It is much easier for patients to allow a wand to scan the mouth than to have creamy material placed in an impression tray and allowed to set for several minutes while the patient tolerates the bulky material with their mouth open.
The technique I prefer is to have a combination healing cap and a scannable abutment. This way, the patient comes in, and a scan is done without the need to unscrew anything. The scanner can choose the color of the new crown, or the dentist can choose using a shade guide, essentially the same as paint samples. Different colors are placed next to the tooth until the closest match is found.
How is the Crown made?
Scans are three-dimensional digital data files. The data is used with milling machines. The technician designs the tooth, and the milling machine does most of the work. Some offices have the machine right there, so conventional crowns can be placed immediately on natural teeth. With implants, however, a custom abutment is usually required. The custom abutment is the piece that will replace the healing cap. It is screwed into the implant's internal threads to a specific torque. The screws are metal and deform slightly, making the interface tight and durable. Once the abutment is screwed in, the crown can be cemented over it, just like a conventional one.
I prefer that the lab place the crown on the abutment and leave an access hole in the biting surface of the crown. This way, I remove the healing screw, place the crown/abutment onto the implant, and screw it in. Once the crown is in place, I put a small tooth-colored filling in the access hole. The filling allows me to remove the crown if any problems arise.
How Good are Implants?
The survival rate of implants is as good as natural teeth. Of course, no healthy teeth are guaranteed to last forever, but they have a fifty-year survival rate of 99.5%. Teeth with problems still achieve a survival rate of around 92%. Implants come in at 82-94%. 1 In this post, I have been writing about single implants, but multiple teeth can be replaced with implants. In many cases, only four to six implants are needed to permanently replace an entire arch of teeth. In other cases, implants are used to snap dentures onto them.
Titanium or Zirconia?
In recent years, implants made of zirconia have been used. They are less popular than the titanium ones. The initial and subsequent studies show that bone adheres well to them. The research has been done on one-piece zirconia implants. Zirconia implants were one-piece for a few reasons. First, the titanium interface between the implant and abutment produces small titanium particles, thought to cause inflammation. The research is scant on this subject, and titanium implants are no more inflamed than their zirconia counterparts. Second, screws don't work well with zirconia. The strength of screw-retained abutments is that the metal deforms, helping to lock it in. This does not happen with zirconia.
Since the angle at which an implant is placed may not be ideal, the custom abutment can be a perfect remedy for angle disparities. Not so with one-piece implants, causing them to have limitations.
As far as I know, only one study looked at screw-retained zirconia versus titanium implants. No clinically significant difference was found. However, there were only 28 subjects, so the results should be taken cautiously. In addition, the abutments on the zirconia implants were cemented because, as I mentioned, screws don't work well with zirconia. Lastly, cementing abutments presents significant challenges to clinicians.
Conclusion
https://www.schoolmykids.com/learn/periodic-table/compare-titanium-zirconium
I have many more holistic-oriented patients than the average dentist. Most of them come in with the notion that zirconia is superior to titanium. Unfortunately, the research to date does not bear their beliefs out. Many don't want foreign metals as part of their bodies, which I fully understand and support. However, zirconium is considered part of the titanium family on the periodic table of elements. They are both considered transition metals. As such, they are both in the d-block on the table. Both are silver in color. 2 We refer to zirconia implants as zirconia, but they are made from zirconia oxide, which appears white. 3 I do not believe zirconia implants are any better than titanium. I am for their use because they seem to work well, but the research is scant. Lastly, finding practitioners who use them is limited, making them less practical. If you are interested in having zirconia implants, a quick internet search should yield sever practitioners who use them.