This article was written by Dr. Noumbissi and published in the January 2013 edition (International Section) for the Orofacial Chronicle Journal from Bhopal, India.

Background

Since Dr. Brånemark first introduced titanium dental implants, a variety of materials have been used successfully for about 40 years. Today implants are made either of commercially pure titanium (cpTi) or titanium alloys.  In addition to its biocompatibility, titanium was also initially believed to be inert, nontoxic and nonallergenic1,2. However, several drawbacks have been documented in the literature with the use of titanium and titanium alloys as implant materials in medicine and dentistry. High concentrations of titanium have been detected in tissue surrounding dental implants mostly as a result of wear or corrosion of the titanium implant surface.  In an animal study Weingart et al.3   showed that nine months after titanium implantation, titanium particles had spread and were found in adjacent lymph nodes. This indicates the possibility that phagocytes could transport titanium particles to the lymph nodes without any initial or immediate inflammatory response and potentially cause later immunologic reactions.

The Facts

An increasing number of people who suffer some form tooth loss are choosing to replace their teeth with dental implants. For the last thirty plus years the only and highly successful option for freestanding tooth replacement available in the United States and other countries has been titanium and titanium alloy dental implants. There are increasing reports both in dentistry and medicine of individuals developing sensitivity and allergies to titanium and/or titanium alloys. Even of more concern some of these implants are corroding once exposed to body fluids such as saliva and developing electrical activity when they are coupled with prosthetic components made of other metal alloys. Titanium implants as they corrode are known to release metal ions which create low level electrical currents through the body but also weakens the structural integrity of the implants. With recent advances in implantable biomaterials research and technology, bioceramics such as zirconia (zirconium dioxide) are now available and a new generation of modern implants is made of zirconia. Zirconium Silicate (ZrSO4) is mined and is treated and transformed into zirconium dioxide which is also called zirconia. Zirconia is the crystal form of the material zirconium which is a transitional metal. After mining and processing of zirconium silicate, zirconium is isolated and further processed under high temperature and pressure. Zirconium then undergoes an oxidation and crystallization process which allows it to transition into a structurally stable and inert crystal. This bioceramic crystal is called Yttrium Stabilized Tetragonal Zirconium Polycrystal (Y-TZP) also called zirconium dioxide. Therefore zirconium dioxide is not a metal and presents exceptional physical and biological properties. Zirconia can sustain an extreme load capacity, features a very long service life, and presents no conductivity or interference in the body’s meridian systems; it is the most hygienic, non-electricity conducting and stable material for dental implantology and orthopedics. Zirconia implants also present no danger of corrosion, something that is often a serious problem with metal based dental implants. Corrosion of a titanium dental implant occurs when it is coupled with the metal framework or abutment of the crown which more often than not is a less noble metal or alloy than that of the titanium implant. The implant and crown assembly bathes in saliva which is an electrolyte and a good conductor of electricity; this leads to all sorts of chemical and electrical imbalances in the body and to a phenomenon called “battery mouth”. Another advantage of zirconia is its low affinity for plaque (picture#1). Clinical observations and studies show that zirconia implants compared to or next to titanium implants accumulate much less plaque and allow for superior gingival health (picture #2).

Radioactivity and Zirconia Implants

There is a controversial and highly misunderstood aspect of zirconium dioxide in terms of its radiological output. Zirconium Silicate (ZrSO4) depending where it is mined can be contaminated with natural radioactive isotopes including radium (226Ra) and thorium (228Th). This was a major concern in the early 1990’s because the ores selected were contaminated. Today zirconium dioxide processing plants have the technology to remove these contaminants and are able to yield and use very pure powders. For example, the radiation emitted by a 3 mol% Y2O3-ZrO2powder was the same order of magnitude as alumina powder, both of which were several orders of magnitude less than that typically measured for water, vegetables and livestock. Zirconia hip ball replacements weigh approximately 100mg and have a natural radiological output of 1mSv per year. The average weight of a zirconia dental implant is 1g, translating into a natural radiological output of roughly 0.01mSv/year. Therefore the radiation risk of zirconia bioceramics is negligible and given that the World Nuclear Association states that the typical background radiation experienced by most people in North America is 3.4mSv, there is little concern for adverse biological effects on the implant recipient.

Conclusion

Zirconia dental implants are a sensible and clearly a healthier alternative to conventional and titanium implant bridges, partials or Overdentures. Furthermore zirconia by virtue of its translucency and all-white color makes it the most aesthetically pleasing option available today for tooth replacement (picture #3 & picture #4). This is a new era in implant dentistry and the science of oral implantology.

Referrences:

1-  Rabin, Steven I., MD; Calhoun, Jason H., MD, FACS, editor: Immune Response to Implants  

2- Allauddin A Siddiqi, Alan G T AG Payne,Warwick J WJ Duncan. Titanium allergy: could it affect dental implant integration? Clin Oral Implants Res 22(7):673-80 (2011)  

3- Weingart D, Steinmann S, Schili W, Strub JR, Hellerich U, Assenmacher J, Simpson J. Titanium deposition in regional lymph nodes after insertion of titanium screw implants in the maxillofacial region. Int J Oral Maxillofac Surg.1994 Dec:23 (6Pt2): 450-2  

4- Scarano A, Piattelli M, Caputi S, Favero GA, Piattelli A. Bacterial adhesion on commercially pure titanium and   zirconium oxide disks: an in vivo human study. J Periodontol. 2004 Feb;75(2):292-6

Metal-Free Dental Implants vs. Dental Bridges

The science of ceramic, metal-free dental implants provides a comfortable and natural alternative to bridges for patients who have suffered tooth loss. Metal-free dental implants are made of the ceramic component of zirconium also called zirconium oxide or zirconia. Due to zirconia’s physical and optical properties, metal-free implants are all-white in color , highly attractive in appearance,  and look and feel like natural teeth so much so that you might forget that you ever lost a tooth (for more information about the cosmetics of metal-free dental implants, please read The Cosmetics of Ceramic Dental Implants).

What’s the Difference Between Dental Implants and Bridges?

A conventional dental bridge can be made with a metal framework or entirely from porcelain or zirconia. However whether its metal based or ceramic, it is created by using adjacent teeth to support a pontic, or fake tooth. In this way, otherwise healthy teeth are often ground down and crowned (or “capped”) to facilitate a bridge to span the space where teeth are missing. So what is the difference between a bridge and a dental implant? A dental implant is applied directly into the jawbone mimicking the tooth’s natural structure without touching the surrounding teeth. An even better method of tooth replacement is by using zirconia implants therefore taking advantage of its metal-free and extremely stable physical properties. Zirconia dental implants do not corrode or breakdown when in contact with oral fluids, furthermore little to no plaque (tartar) accumulate on their surface.

How Long do Dental Implants and Bridges Last?

FAQ About Dental Bridges:

Most dental bridges last from 5-10 years before needing to be replaced. A bridge relies on the adjacent teeth and on the bridge’s structure for support. Surrounding teeth lose their strength due to being ground down to support a bridge and are susceptible to decay and even fracture due to loss of enamel and tooth structure in the process.

FAQ About Metal-Free Dental Implants:

Metal-free dental implants can last a lifetime and are placed directly into the bone where the teeth are missing. They do not adversely affect the adjacent healthy teeth, do not corrode or conduct low level electrical currents in the oral cavity. These low level electrical currents also called galvanic currents will lead to events ranging from weakening of conventional metal implants to the death of bone cells around implants;  this eventually leads to implant loosening and failure. Zirconia implants bond to the jaw bone and become part of it without affecting it – making a connection often stronger than a natural tooth root.

Do Bridges and Metal-Free Implants Cause Bone Loss?

Dental implants act as substitute tooth roots, providing the same function as natural tooth roots including stimulating the bone in the most natural way possible.  When teeth are removed or lost due to trauma or infection the underlying bone is no longer used, frequently resulting in a weakened jaw and bone loss. This makes it difficult to smile, chew and do other things most of us take for granted.

FAQ About Dental Bridges:

When teeth are lost or extracted, the bone that previously supported those teeth no longer serves a purpose and begins to deteriorate, or ‘resorb’. When a bridge is used to connect two teeth, normal pressure is not applied on the jawbone in such a way that the bone is stimulated as it would be in a healthy mouth, leading to bone loss in the area where the tooth was lost. Eventually the bone loss spreads to the supporting teeth of the bridge which over time gets loose, fractures and/or fails.

FAQ About Metal-Free Dental Implants:

Just like metal (titanium) implants, replacing teeth with metal-free dental implants involve placing an artificial root made of zirconia back into areas where there are no teeth. This results in renewed stimulation of the bone in the jaw preventing long term bone loss, thereby preserving and strengthening the structure of the jaw.

Not only do dental implants sit securely in the jaw and look like natural teeth, they also offer superior durability and outstanding aesthetics. Implants of a variety of materials have been used successfully for about 40 years and the latest generation of ceramic implant systems made of zirconium oxide (zirconia) take the science of dental implants to the next level.

Are Dental Bridges or Ceramic Implants Easier to Clean?

Caring for dental implants is very much like caring for natural teeth by following standard oral health care measure such as brushing and flossing.

FAQ About Dental Bridges:

Flossing bridges is not an easy task and requires time, patience and consistency making it difficult to follow routine everyday oral hygiene which can leave the underlying natural tooth structure at risk of decay and gum disease. Almost invariably over time decay occurs under supporting crowns of the bridge leading to the need for root canal treatment or tooth loss altogether.

FAQ About Metal-Free Dental Implants:

Individual dental implants allow easier access between teeth making it possible for patients to resume normal dental care. Furthermore zirconia dental do not collect plaque around them allowing for healthier gums and underlying bone.

Should You Choose a Metal-Free Dental Implant or a Bridge?

The bottom line for most people who have experienced tooth loss is that dental implants are a better solution. Implants are the closest thing possible to natural teeth, are fixed in place and offer a healthy alternative for oral and bone health, plus they support general well-being. Patients, who have metal-free dental implants a less likely todevelop metal sensitivity over time, remark that they look better, feel better and are more confident.

This slideshow is an extended  version of  Zirconia implant placement in Compromised Bone released on 03/01/2012. More often than not and especially in emergency cases, patients are undecided about the method of tooth replacement they desire a the time of tooth removal. As a result extractions are done in a conventional manner and even with the greatest care bone defects can be  created during the process of extraction. The natural process of bone resorption during healing after extraction can also make things even more complicated.

Warning: This is a surgical slideshow with graphic depictions and images of a bone grafting procedure and ceramic dental implant placement.

Zirconia Implant in Defective Bone_Surgical Version from Sammy Noumbissi DDS MS on Vimeo.

Today there is an increasing amount of people who choose to have their teeth replaced with dental implants. In some cases the replacement is immediate meaning that once teeth are removed, during the same surgery implants are placed to replace those previous teeth. The advantage of replacing a tooth with an implant at the time of extraction is that the amount of bone loss at the site of extraction is greatly minimized.  However for most people the decision or option to have their teeth replaced comes long after their teeth were lost, and after years of wearing removable partials, dentures or having fixed bridges anchored to adjacent teeth. The problem often encountered in  such cases is that the bone in the area where the teeth have been missing shrinks and there is significant loss of volume and height making it challenging to place implants . A bone augmentation or reconstruction procedure is then necessary and occasionally must be done prior to and in preparation for implant placement, this is what is commonly called a bone graft.

When situations of bone loss or long term absence of teeth present themselves the first step is to obtain the proper information for accurate diagnosis. A clinical and ultra low radiation 3D X-ray is taken of the jaw to be treated, the x-ray unit we use in our practice is called a Cone Beam CT Scan (CBCT) and it provides an accurate view and analysis of the problem. The slide show below shows how by means of clinical pictures and  dental CT scan we are able not only to plan the volume of bone that needs to be augmented but also with a second scan assess the success of the bone graft.

This is a case report published in Prexion3D’s December 2011 newsletter.  All phases of this case were completed by Dr. Noumbissi. A patient had a missing tooth in the anterior maxilla, 3D dental imaging technology (CBCT) and software (InVivo5) were utilized to adequately and accurately plan the placement and temporization of a metal free zirconia dental implant.

The  CBCT radiation from the Prexion is extremely low compared to medical CT scanners. The InVivo 5  software was used to perform virtual implant placement prior to surgery. From the  implant placement simulation a surgical guide was generated using CAD/CAM technology.  The surgical guide was then utilized to place the implant in a precise manner allowing for much safer and more predictable implant placement.
Sammy Noumbissi DDS MS

Using Cone Beam CT (CBCT) Technology to Plan Zirconia Implant Placement in a Bone Deficient Site.