On November 30, 2012, Dr. Noumbissi spoke at Columbia University School of Dental Medicine. In attendance were the faculty and postgraduate students from the department of Periodontics and Implant Surgery, Prosthodontics and from the International Implant Program. Professor Charles Berman one the the elder statesmen of implant dentistry and the faculty in the periodontics program facilitated this event. I would like to thank all that were in attendance and their high interest in this revolutionary area of dental implantology .

Why ceramic dental implants are better than conventional bridges?

When it comes to options for tooth replacement patients are increasingly opting for dental implants over the usual dental prostheses such as dentures or conventionally placed bridges. Since implants sit securely in the jaw and look like natural teeth, they offer superior durability and outstanding aesthetics when compared to conventional bridges. However there is an increasing resistance to metals among people and in implant dentistry there is a shift away from metal or metallic based crowns, partials and implants.

There are four major categories of restorations available for tooth replacement:

Bonded dental bridge

Bonded dental bridges use the teeth adjacent to the empty space to help support the missing tooth by using a very thin piece of metal or tooth-colored material to overlay and bond to the back of the adjacent teeth. A tooth replacement or “dummy tooth” is set between these two bonded pieces in order to fill in the empty space. Failure rate is about 25 percent after just five years of use. Furthermore the gap widens because the bone recedes as a result of no longer having a tooth in place. This ultimately results in the weakening of the adjacent teeth which can become loose and eventually fall out.

Cantilevered dental bridge

A cantilevered restoration uses the closest tooth next to the empty space to support the missing tooth using the either the back of the neighboring tooth or a full crown to help support the missing tooth. Success rate is higher than with a bonded bridge depending on how much pressure the actual replacement endures due to grinding and normal wear. This method of tooth replacement has fallen out of favor because the supporting tooth gets torqued and fatigued and more often than not eventualy fractures.

Conventional dental bridge

Getting fitted for a dental bridge requires shaving down and modifying of the teeth on either side the space where the tooth or teeth are missing. This is done in order to fit a conventional bridge. This is a process that significantly weakens the ground teeth and sets them up for fracture and root canals in the future. Unfortunately conventional dental bridges predictably fail at a range from 20 percent over 3 years to 3 percent over 23 years.                                                                                                      With dental implants the dentist does not need to affect the health or longevity of neighboring teeth at all. Once placed, implants are firmly set into the bone making them more natural than dentures or conventional bridges, with none of the shifting that dentures normally display.

Some problems with conventional bridges

• They are bonded to the adjacent tooth with a glue-like substance, bridges more often become loose and fall out
• They cracks and fissure form over time, due to normal wear and tear and become fragile and prone to breakage
• Improper fit can lead to either tooth decay or irritation to the surrounding soft tissue around them.

Dental implant

A ceramic dental implant is created from a high performance material (zirconium oxide) that is inserted into the bone to act like a natural tooth root. Zirconium oxide also called zirconia is a crystal phase of zirconium and due to its nonmetallic construction the ceramic dental implant does not interfere with the body’s immune or meridian systems and therefore significantly reduces the potential for rejection. Furthermore ceramic implants do not interact with electromagnetic fields such as those emanating  from cell phones, cell phone towers and microwaves. Once inserted into the jaw, the implant integrates directly into the bone to give firm support to the artificial replacement that it is built to hold and should last the lifetime of a patient. Routine maintenance of a dental implant is exactly the same as a person would follow for normal teeth.

Healthy Patients Prefer Ceramic Implants

Patients who prefer dental implants say that they are more comfortable and provide a more secure fit than fixed bridges or removable dentures. However all implants are not equal and ceramic implants unlike metal implants are made in one piece from the root to the top just like a natural tooth. Therefore ceramic implants do not have joints and do not retain plaque and harbor billions of bacteria like two-piece metal implants. For those who no longer have any natural teeth, ceramic implants can be placed to support and retain dentures and eliminate the embarrassment and discomfort they can cause in social situations when they slip and click. Loose and ill-fitting dentures hamper the everyday pleasure of eating comfortably.

Reasons to consider a ceramic dental implant:

• preserves healthy natural tooth and bone structure
• looks and feel like natural teeth
• enhances a sense of self-confidence when eating, talking and smiling
• no gooey denture adhesives to deal with
• no embarrassingly loose dentures
• improves quality of speech
• no electrical or electromagnetic activity in your mouth

Anyone who is missing one or more of their teeth may be a candidate for implants. If more than a few of the teeth are missing, implants in supporting a crown or bridge can replace those teeth and function as normal teeth without concern for loss of bone and decay. If all or most of the teeth are missing, then implants may be placed to fix in place a full-mouth non-removable set of teeth.

No such problems with ceramic implants

Ceramic dental implants are recommended to patients because:

• Chewing is easy with excellent biting pressure provided by implant
• When done properly and dilligently cared for, dental Implants are reliable and provide long-standing service, for decades with few, if any complications
• Comfortable fit and lifetime durability because they are well secured and integrated with the bone and gums
• They remain clean because they do not accumulate plaque and bacteria
• Metal-free bioceramic
• They do not generate nor conduct electricity

Considering the overall advantages patients can expect to benefit from as a result of choosing a dental implant, they are better able to enjoy a healthier and greener lifestyle without the restrictions many denture and bridge wearers face. The more secure foundation offered by a dental implant, the better biting pressure becomes, making it possible to enjoy the foods that a patient probably would not be able to eat using a dental prosthetic. As a result improved chewing ability leads to better nutrition and improved overall health.

Biocompatible Zirconium Oxide Ceramic Dental Implants

In the world of medicine, zirconium oxide is being used more consistently as the material of choice for bone related reconstruction, particularly hip prosthesis. This growing trend has led to substantial clinical reports which confirm the high biocompatibility and quality of zirconium oxide, making it an attractive component for use as dental implants. Not only does Zirconium Oxide overcome most of the pitfalls of other dental implant products (such as Titanium), but patients now have a choice of a material that is esthetic, strong, pure, corrosion-free, biocompatible and capable of being used for all dental implant and appliance applications.

Why biocompatibility is so important

The immune system will typically respond to non-compatible dental materials as if they were infections or ‘invaders’ by initiating a cascade of reactions geared toward eliminating that ‘invader’. A good analogy to this would be how your body reacts to a cold or flu by elevating levels of lymphocytes and activating the immune system, a reaction that eventually rids the body of the cold or flu. The difference is that with dental toxicity the source of the problem is permanently imbedded in the mouth, and therefore there is no way for the ‘infection’ to be eliminated by the immune system.

Using only quality biocompatible materials that are proven to have very low adverse allergic reactions and present no negative responses from the immune system is highly important for the health of our patients. It is also the reason that biological, natural and holistic dental practices strive to use only materials that are as neutral as possible. Zirconium is a very strong, inert material with very low allergic potential and therefore a higher biocompatibility than other materials used as dental implants.

What non-compatibility looks like

Considering that every person’s body and physiology is unique, some individuals will be more compatible than others with certain types of materials used in dental treatments and procedures. But ultimately, a biocompatible material will not cause:

• allergic reaction
• irritation
• inflammation
• foreign body response (rejection)
• cancer and other autoimmune disorders

An all-ceramic dental crown over an all-ceramic dental implant looks and functions very much like the missing tooth did. Ceramic implants provide metal-free tooth replacement solutions, eliminating concerns of allergies and biocompatibility issues thereby lessening concerns for damage to the immune system. Zirconium Oxide provides safe, holistic results that are comfortable, natural in appearance and biocompatible:

• Zirconia implant is the holistic dental implant for absolute metal-free dentistry
• The white color of Zirconium far surpasses the metallic appearance of Titanium
• Ceramic implants and crowns retain less plaque and calculus than Titanium and therefore promote healthier gums and mouth

Our objective is to make as many biocompatible options available to our patients as possible and it is important to us to achieve the highest level of biocompatibility, particularly in cases where patients have compromised immune systems. Whenever considering a dental restoration we strongly suggest that extensive biocompatibility and metal allergy testing be done beforehand to ensure the best results.

For the second year in a row, we had a very successful and fulfilling day. We had over 150 visitors stop by our booth and we were able to share and enlighten  the public on the virtues of replacing missing teeth or stabilizing loose dentures and partials without using metal dental implants. Miles of Smiles Implant Dentistry is one of the few practices in the world that offers top-to-bottom metal free teeth replacement solutions. The  implants we use are made with a bioceramic called zirconia or zirconium dioxide. Zirconia is the ceramic phase of zirconium and it is not only biocompatible but also biologic. Unlike metal implants (titanium), zirconia implants are not susceptible to corrosion, will not break down and does not allow low level electrical activity in the mouth.

“Can I Be Allergic to Titanium Dental Implants?”

Discover the Links Between Metal Allergies and Dental Implants

By far, the most commonly implanted metals used in orthopedic and dental restoration devices are cobalt/chrome, stainless steel and titanium. Virtually all implants are alloys, meaning they are a combination of several different metals. The base metals (iron, nickel, lead, zinc and copper) are found in the highest quantities, but smaller amounts of other metals are also found in the implant. Considering that roughly ten to fifteen percent of the population experiences some form of allergic reaction to metal it is important to consider alternatives to metal implants.

Why All the Fuss about Metal Allergies?

An allergic reaction is a response of the body’s immune system when it detects an invasion of foreign substances, whether living or non-living. Allergic responses can range from a mild rash to death from a multi-system shutdown known as anaphylaxis. A person can become allergic to virtually anything, anywhere and anytime, including metals.

Environmental exposures to metals include; joint replacement, dental implants, dental restorations, jewelry, body piercings and even mobile phones. Traditionally nickel, cobalt and chromium have been the most prevalently reported contact allergens; however gold and palladium (primarily alloys that contain more than one metal) have drawn more attention recently. In the United States, studies show that the prevalence of nickel allergy is on the rise (likely due to the growing popularity of body piercings). Metal allergy is also being reported in association with certain device failures following surgical placement such as stents into coronary (heart) blood vessels, hip and knee prostheses, as well as dental and other implants.

Metal Dental Implants – originally the only choice

Metal dental implants were originally made out of commercially pure titanium or titanium alloy, providing the only option for anyone wishing to undergo implant tooth replacement. One aspect of titanium and titanium alloys is that they are generally considered ‘osteophilic’ (bone-friendly) and therefore considered to be biocompatible, providing a clear improvement over dentures and bridges. With a growing body of evidence to the contrary provided by researchers and patients alike, we now know that placing metallic dental implants and other restorative devices can potentially provoke allergic reactions and implant failure. One study involving 1,500 patients helped to drive the fact home when it demonstrated that titanium allergy could be clearly detected in dental implant patients. A notably higher risk of positive allergic reaction was found in patients whose implants failed for no other known reason other than that they had a higher incidence of allergic reaction.

Worst Case Scenario – Autoimmune Disorders

The most significant symptom which can cause the most severe problem is ‘chronic fatigue’. Muscle pain and chronic fatigue presenting without any known cause are the more serious symptoms associated with an allergy to metals. Unfortunately, since people don’t usually link overall fatigue with an immune disorder stemming from a metal implant they can suffer from this type of reaction for months or years before seeking help.

Autoimmune Disorders on the Rise

Between 15 and 25 million Americans are reportedly affected every year by one autoimmune disorder or another.  When you realize that an allergic reaction is actually the immune system turning on itself in a state of hyperactivity of the immune system then you can begin to see the correlation between autoimmune disorders and allergies, and doctors are now beginning to realize that allergies are quite often a precursor to autoimmune disease.

A growing list of health problems are suspected to be related to metal allergies potentially instrumental in the onslaught of autoimmune diseases such as Chronic Fatigue Syndrome, Psoriasis, and Scleroderma, Lupus, Rheumatoid arthritis, type I diabetes, Multiple Sclerosis, Hashimoto’s thyroiditis, Guillain-Barre syndrome, and others.  With this alarming rise in autoimmune diseases and the suspicion of a correlation between metal allergies and a weakening immune system it only makes sense to take whatever steps we can to ensure that our patients are biocompatible with an implant before allowing any substance or material to be permanently affixed into the mouth.

The Better Alternative That Can Last a Lifetime

Today, ceramic dental implants are considered to be the best and safest alternative to metal implants. The advantage of these implants is that they are ceramic, they are made from zirconium oxide also called zirconia and thus there is no concern of corrosion, allergic reaction or electronic interference. Overall qualities of ceramic dental implants include;

Biocompatibility: the zirconium used in the manufacture of ceramic dental implants is an inert material with very low allergic potential.
Strength: The strength of the dental implant is exceptional compared to other metal implants.
Metal-free: no corrosion, no galvanism effect, no metallic taste, no electronic disturbances and no Gum irritation.                                             Hygienic: Oral plaque and tartar do not accumulate on the surface of zirconium imlpants, therefore they remain clean and allow for a healthy environment around the implant bone and soft tissue.

Allergy Testing – An Important Part of the Whole

Our goal is to treat the whole person through the use of safe, natural and painless methods. Our innovative approach to dental care focuses on the health and wellness of the mouth in relation to the whole body, including identifying and treating issues pertaining to metal allergies and autoimmune disorders. We only recommend products that we know to be safe and that will provide the most positive, lasting results for our patients, such as ceramic dental implants. To learn more call to schedule your free personal consultation today.

The Question of Radiation in Dental Ceramics

It may be surprising that one of the ‘risks’ associated with Zirconium based implants is radioactivity. But what does the research say, and is there really any risk to patients? The truth is that Zirconium just like aluminium and many other commonly used materials can contain a certain number of radioactive isotopes, which in extreme cases can increase the chance of oral cancers. However, oral implants are produced from a highly purified and stabilized form of Zirconium also called zirconia or zirconium dioxide which contains extremely low radiation emission levels. Furthermore all manufacturers of zirconia dental implants are required to provide a declaration of radioactivity for their zirconium based dental products. Therefore all zirconia products and materials are not created equal, because the quality and safety of each lies in the the processing of the raw material zirconium.

The Radioactivity of Commercially Available Zirconia Powders

Zirconium compounds are refined from naturally occurring ores, notably zircon, which usually contain trace amounts of other elements depending upon the source of the original ore. In particular, zirconia typically contains trace amounts of radionuclides. As a consequence there were some concerns about the use of zirconia ceramics as implant materials.

In 1992 the question of radioactive ceramics was officially addressed by Anusavice KJ in an article titled ‘Degradability of dental ceramics’ which observed in part that … “The degradation of dental ceramics generally occurs because of mechanical forces or chemical attack. The possible physiological side-effects of ceramics are their tendency to abrade opposing dental structures, the emission of radiation from radioactive components…”

However alarming that may sound further research indicated that the radiation emitted by a dental ceramic powder (3 mol% Y2O3-ZrO2) was the same order of magnitude as alumina powder, both of which were several orders of magnitude less than that typically measured for water, milk, vegetables and meat (based on European standards). The radioactivity of zirconia femoral heads (Y-TZP artificial hip joints) for example, has been shown to be similar to that of alumina and cobalt-chrome. The radiation dose of each material was recorded at that time to be well below European radiation limits specified for general external exposure of the human body and also for local internal exposure of organs and tissue, and was well recognized as no more than the ambient radiation of environmental surroundings.

In another similar study, radiation levels of several commercially available zirconia powders commonly used to manufacture implants in Australia (Nilcra Ceramics, Melbourne) were declared to be minimal and well below acceptable limits. The Radiation Health Committee of the National Health and Medical Research Council of Australia now consider that magnesia partially stabilized zirconia artificial hip joints made from these powders pose “very little hazard to surrounding tissue”.

The main raw material for the manufacture of zirconium dioxide (zirconia) in the US is the mineral zircon silicate (ZrSiO4) which is translated to a higher form of purity zirconium dioxide (ZrO2) when melted with coke and lime. Since extremely pure initial products must be used for the production of high-performance ceramics used in dental implants, special synthesis methods have been developed specifically for this product; a process that works to create the strongest, most durable dental ceramic product available today.

Radiation Absorption

Research has shown that in a dense ceramic almost all radiation is absorbed within the bulk of the material. In the case of artificial hip joints, any radiation from the femoral head is absorbed primarily by the surrounding artificial materials.

From these tests and others, it is widely recognized in the medical implant field that the actual radiation risk of zirconia ceramics is negligible, certainly no more than that of alumina – and consistent with the level of radiation found to occur naturally in healthy environments.

The Benefits of Zirconium Implants and Dental Ceramics

Overall, Zirconia (zirconium oxide) implants are valued by dentists and patients alike for being highly resistant to corrosion and superior to other available implant options such as titanium, both as related to biocompatibility and resultant color. They are ideal for those patients whose immune systems do not accept titanium implants and for patients who may have allergic reactions to metals. Zirconia implants are far more durable with less risk of breakage and is capable of holding up to the drastic changes in temperature and chemistry found in the oral environment. Being bright white in color, zirconia implants have a definite advantage or aesthetic value over titanium dental implants by eliminating the possibility of corrosion and the unsightly grey appearance that titanium exhibits.

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Resources:

Is There A Renewed Trend of Radioactive Compounds In Dental Materials? — Ulf Bengtsson, 2000-01-01

Abstracted from Ph.D Thesis “Application of Transformation-Toughened Zirconia Ceramics as Bioceramics”, University of New South Wales, Australia, 1995.

Anusavice KJ. Degradability of dental ceramics. Adv Dent Res 1992 Sep 6:82-9

What are the Benefits of Ceramic Dental Implants?

Well over 100 million Americans suffer some form tooth loss, and today ceramic dental implants represent the most aesthetically pleasing option available for tooth replacement. Ceramic implants are comfortable for our patients, and due to their all-white color they present the most natural looking results. Dental implants are the better alternative to bridges, partials or dentures (find out why ceramic implants are better than bridges here) and most importantly; ceramic dental implants perform just like natural teeth.

When teeth are removed or lost due to trauma or infection the underlying bone is no longer used, 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. Furthermore teeth next to the lost tooth/teeth shift and and the opposing one(s)  drift into the spaces left by missing teeth. These ultimately lead to malocclusion, jaw collapse, jaw muscle pain and even chronic headaches. Dental implants provide the same function as the natural tooth root which they replace, including stimulating the bone in the most natural way possible and maintaining adjacent and opposing teeth in their place. Ceramic dental implants prevent bone deterioration and improve a patient’s ability to chew food normally.

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 as do traditional bridges. Implants bond to the jawbone and become part of it – making a connection as strong as a natural tooth root.

Some of the benefits of ceramic dental implants:

• Improve one’s ability to bite and chew
• Function exactly like natural teeth
• Do not interfere with adjacent teeth
• Provide a more youthful appearance to the face and jaw line
• Eliminate bone deterioration that can occur with tooth loss
• Do not cause unsightly metal coloring around the gums
• Are metal free and do not corrode or breakdown in the oral environment
• Easy to keep clean because they do not attract nor accumulate bacteria-loving plaque
• Do not conduct electricity or interfere with the body’s meridian energy pathways
• Provides stability without the need for messy adhesives

Whether you’re concerned about metals in the mouth or prefer to have natural looking teeth, ceramic dental implants provide the best alternative to titanium dental implants.

For more information or a free consultation, please give us a call today: 301-880-1410

Brushing our teeth is an exercise in self-care that most of us do at least twice a day but there is also something we seldom consider; the health of that toothbrush. It might shock you to realize that literally millions of microorganisms (bacteria) live on the bristles of your personal toothbrush. That comes down to millions of microscopic bugs that can potentially cause flu, colds and other illnesses.

Recent studies have confirmed that oral health is connected with overall healthfulness. For example, there is a strong correlation between heart disease, diabetes, premature delivery in pregnant women, and strokes; and gum disease. Researchers discovered there are upwards of 10 million bacteria live on the typical toothbrush and we know that tooth decay is also caused by the type of bacteria that can survive on toothbrushes.

Studies have proven that cold and flu viruses and even the viruses that cause fever blisters (Herpes Simplex I) can survive on toothbrushes for several days – infecting and re-infecting the unsuspecting owner of that toothbrush. Here are just a few viruses that thrive on toothbrushes and some of the problems they can cause:

• E. Coli: bloody diarrhea and severe abdominal pain and tenderness with no fever
• Influenza Virus: fever, cough, headache and fatigue, sore throat, vomiting and diarrhea
• Staphylococci Bacteria: abscesses, boils, and skin infections
• Herpes Simplex I: can affect the mouth, face and skin and can be present in the body without symptoms, generally causes recurring and painful blisters (cold sores or fever blisters)
• Candida Albicans: mild nasal congestion, blisters in the mouth, sore throat or abdominal pain, and/or fatigue, dizziness and mood swings
• Coliform Bacteria: usually present along other disease-causing bacteria and organisms

Some researchers also discovered bio-film thriving on toothbrushes, which is living colonies of breeding bacteria, with estimated numbers as high as 100 million microorganisms existing on individual brushes.

Protecting Your Toothbrush

Surprisingly, it isn’t the bacteria from your mouth that contributes to the worst bacterial problems on a toothbrush, it’s the fact that most people store their toothbrush unprotected in the open, on
the bathroom counter top. By far, flushing the toilet is the worst culprit for germs found on most toothbrushes. Every time you flush the toilet invisible jets of water propels germs into the air, where they can land on toothbrushes.

Family toothbrushes stored side-by-side only compound the risk of sharing germs and viruses. Bacteria, molds, and fungi love moist environments provided by most bathrooms and they also love dark enclosed spaces, so storing toothbrushes in the medicine cabinet may not be as ideal as you might think.

While most dentists recommend replacing your toothbrush every couple of months, most American’s aren’t likely to change their toothbrushes more than twice a year. Here are some steps you can take to keep your toothbrush germ free:

Storage: Store toothbrushes away from the toilet in a cool, dry place.

Rinse well: Wash off your toothbrush thoroughly with tap water every time you use it.

Dry it after use: Dry your toothbrush thoroughly between brushings and avoid using toothbrush covers, which can create a moist enclosed breeding ground for bacteria.

Store it upright. Store your toothbrush upright in a holder, rather than lying it down.

Keep it to yourself: Never share a toothbrush and avoid storing it side-by-side in the same container with other people’s brushes.

Ultraviolet Light: Studies indicate that ultraviolet light can be effective in killing germs on toothbrushes and are able to kill many of the bacteria, yeasts, and viruses. A study conducted at New York University Medical Center on countertop ultraviolet toothbrush sanitizers found that this device eliminated up to 99.9 percent of bacteria tested on toothbrushes.

Hydrogen Peroxide Rinse: Cheaper than an ultraviolet device and a measure perhaps just as effective could be the practice of rinsing your toothbrush after each use with hydrogen peroxide. Hydrogen peroxide is antibacterial, antifungal, kills mold and mildew and when used properly, it is non-toxic for humans, plants, household animals.

Best practice: keep it clean and keep on brushing

Now that you know how to keep your toothbrush truly clean and germ free as a way to protect yourself and your family from harmful bacteria, it is also important to choose a brush that will do the work of keeping your teeth clean without harming the delicate surface of the tooth or gums. Choose a brush with soft or medium bristles, as they are gentler on the gums and may actually clean better because they’re more flexible. Brush twice a day, at least two minutes each time and rinse your mouth after sugary or starchy snacks. Replace your toothbrush frequently. These practices combined with visiting your dentist regularly for check-ups and cleanings will help to ensure that you have a lifelong healthy smile.

For more than four decades titanium implants have been and continue to be  mainstream in implant dentistry. Most dentists today are trained to use and offer titanium and titanium alloy dental implants which are all metal. However there are increasing clinical reports and scientific research on instances of allergic reaction to titanium implants with spontaneous immediate or delayed implant failures. Other studies have investigated the stability of titanium dental implants and the crowns and bridges placed over them in the oral environment.

Thanks to the stability of the TiO2 layer (oxide layer) on their surface, titanium alloys are exceptionally resistant to corrosion but they are not inert to corrosive attack.  When the oxide layer is broken down and then fails to reconstitute itself, titanium can be as corrosive as many other base metals.  There is increasing evidence that titanium implants when exposed to the oral environment can corrode and result in compromised structural integrity of the implant but also lead to implant loss and potentially life threatening health conditions.

What is Corrosion?

Corrosion can be defined as the graded degradation of materials by chemical or electrochemical attack. This phenomenon is of concern particularly when  metallic implants, metallic/silver fillings, or orthodontic appliances are placed in the hostile electrolytic environment provided by the human mouth. Corrosion can severely limit the fatigue life and ultimate strength of dental materials leading to mechanical failure.

What Type of Corrosion Occurs in the mouth?

The type of corrosive reactions that occur in the oral cavity are electrochemical and are also called wet corrosion. Electrochemical corrosion requires the presence of water or some other fluid electrolytes and in the oral cavity saliva plays that role. This general mode of corrosion is important for dental restorations, implant-to-abutment joints and abutment-to-restoration (crown, bridge, retentive bars etc) connections.  The complexity of the electrochemical process involved in the implant-to-implant superstructure joint and/or connection is linked to the phenomenon of galvanic coupling and stress and pit corrosion.

Galvanic Corrosion

Galvanic corrosion is an electrochemical corrosion, it is the most common form of corrosion that occurs with dental implants. The use and connection of dissimilar metallic restorative materials is called galvanic coupling and may also generate corrosion. Therefore there is a great amount of  concern regarding the types of materials used for suprastructures and crowns over titanium dental implants. When two or more dental prosthetic devices/restorations made of dissimilar alloys come into contact while exposed to oral fluids, the difference between their corrosion potential results in a flow of electric current between them. A galvanic cell is formed in the mouth and the galvanic current causes acceleration of corrosion of the less noble metal. High noble gold alloys are generally chosen as the material of choice for superstructures because of their excellent biocompatibility, corrosion resistance, and mechanical properties. However, these materials have become  very expensive and as a result new more affordable less noble alloys such as Ni-Cr, Ag-Pd, and Co-Cr alloys are used instead. These alloys have good mechanical properties, they are less noble than titanium and their biocompatibility and corrosion resistance are of concern.

The galvanic current passes through the metal/metal junction and also through tissues, which causes inflammation and pain in the soft tissue (gums) and bone. In such cases saliva and other fluids in bone and soft tissue become electrolytes and allow the corrosive galvanic currents to take hold. These events trigger immune responses and ultimately possible implant loss.

Stress and Pit Corrosion

This is the second type of corrosion that occurs at the joint of the implant and the implant superstructure. Implant restorations and abutments can have small microscopic pits and crevices on their surface.  With chewing cycles, implant and implant teeth (abutments and crowns) endure high forces stress of various types such as torsional compression and elongation  and as a result stress and pit corrosion occurs.

Microbial Corrosion

Although not fully proven, microbial corrosion is another type of corrosion that can occur in the oral cavity. Titanium and the various alloys that are used to make restorations on implants are prone to retain a great amount of plaque compared to ceramic/zirconia implants. Wherever there is plaque there is bacteria and microbes living in it, and these bacteria release by-products that destroy bone and make natural teeth loose over time if not removed. In the same manner with titanium implants, those microbes and bacteria by-products are acidic in nature and can potentially corrode the titanium and the metal alloys used for restoration over the implants.

Clinical Observations when Corrosion Occurs in The Mouth

As long as metallic dental restorative materials are employed, there will be galvanic currents associated with electrogalvanism  in the oral cavity. For some patients, especially after the placement of  a base metal restoration, pain caused by galvanic currents can occur and be a source of discomfort  and ultimate implant failure.  Corrosion leads to roughening metal surfaces, release of  ions from the metal or alloy, and toxic reactions. The liberation of elements can produce discoloration of the soft tissues around the implant and allergic reactions such as oral edema, perioral stomatitis, gingivitis. Extraoral manifestation such as eczematous rashes in susceptible patients can occur.  In a study by Kirpatrick, et al, it was found that the pathomechanism of poor wound healing is modulated by specific metal ions released by corrosion.

 Conclusion

The mouth is the portal entry of the human body. It is also the habitat of microbial species that are kept wet by saliva. Oral tissues are exposed to a veritable bombardment of both chemical and physical stimuli as well as metabolism of about 30 species of bacteria. Teeth and dental implants function in one of the most inhospitable environments in the body, they are subject to the most extreme temperature variations, enduring temperatures as low as 0°C to hot foods and beverages. Multiple factors such as temperature, saliva, plaque, pH, and the physical and chemical properties of food and liquids as well as oral health conditions may influence corrosion. Yet, for the most part, oral tissues remain healthy.  The combination of stress, ongoing corrosion, and bacteria contribute to implant structural failure and loss of bone integration.

As it has been the case in orthopedics for almost two decades, we now have alternatives in implant dentistry. Metal-free and metal alloy-free solutions are available for teeth replacement, from the implant embedded in bone to the visible crown in the oral cavity. Zirconia (ceramic) dental implants and all types of all-ceramic restoration (crown, bridge, retentive bars etc) are available. Futhermore bioceramics  accumulate very little plaque if at all thus reducing bacteria habitat, multiplication and by-products. Zirconia dental implants and restorations do not conduct electrochemical currents nor release ions to the oral cavity, surrounding bone and the rest of the body.

References:

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Reed GJ, Willman W. Galvinism in the oral cavity. J Am Dental Assoc 1940;27:1471.

Tschernitschek H, Borchers L, Geurtsen W. Nonalloyed titanium as a bioinert metal: A review. Quintessence Int 2005;36:523-30.

Manaranche C, Hornberger H. A proposal for the classification of dental alloys according to their resistance of corrosion. Dent Mater 2007;23:1428-37.

Chang JC, Oshida Y, Gregory RL, Andres CJ, Thomas M, Barco DT. Electrochemical study on microbiology-related corrosion of metallic dental materials. Biomed Mater Eng 2003;13:281-95

Green NT. Fracture of dental implants: Literature review and report of a case. Imp Dent 2002;11:137-43.

Grosgogeat B, Reclaru L, Lissac M, Dalard F. Measurement and evaluation of galvanic corrosion between titanium/Ti6Al4V implants and dental alloys by electrochemical techniques and auger spectrometry. Biomaterials 1999;20:933-41.

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