As dental implants becomes increasingly popular as teeth replacement, more and more people are having dental implants in their jaws. Today, it is has become a mainstream treatment in many clinics. Along with it widespread adoption, the incidence of complications arising from dental implants is also rising. Countries that have an earlier adoption of dental implants on a widespread scale are beginning to see many complications surfacing. This trend is also beginning to appear in Singapore.
Dental implants in Singapore began about thirty years ago. Back then, there was only one supplier from Europe and they took a very conservative approach towards introducing the product to the market. No dentist was allowed to buy a dental implant or the implant placement kit until he had attended a course specifically designed by the manufacturer. In the beginning, they even limit the course to specialists, though they did relax that ruling soon after. Adoption was slow as the barrier to entry was high. The cost of equipping a clinic to provide dental implant treatment was about $30,000, which was quite a princely sum back in the 80’s. Fast forward to today. There are more than twenty different implant brands available in Singapore, all competing to sell their products. Vendors package the treatment kits with implants and sell them at competitive prices, complete with overseas trips to the country of manufacture to visit the headquarters and factory together with a skiing holiday. The majority of dental clinics in Singapore now provide dental implant treatment. Patients are also more aware and accepting of such treatment.
Intense competition results in competitive pricing. Today, it is possible to have a missing tooth replaced with an implant crown for less than $2000 in Singapore. However, to bring the cost down, some aspects must be compromised. When compromises are made, the chances of dental implant complications may rise.
In the beginning, dental implants were only used for full edentulous lower jaws. Patients who are completely toothless in the lower jaw often have difficulty with complete dentures that are floating around and have poor masticatory function. By implanting five screws into the jaw bone and fixing a full arch prosthesis onto them improves chewing. The implants were left to heal in the bone without any loading for six months so as to achieve maximum integration with the bone prior to fixing the prosthesis. In addition, the lower jaw bone quality is usually very good and that resulted in a high success rate in terms of osseointegration.
Today, dental implants are used for all sorts of indications; from a single tooth to a full-mouth rehabilitation. A wide repertoire of adjunctive procedures has also been developed to augment the jaw bone where it is deficient. In addition, the duration of stress-free healing has been reduced and in some situation, completely eliminated. The number of implants used to support a full-arch prosthesis has also been reduced to 3 to 4. With such an aggressive approach, the complication and failure rates are bound to rise.
Higher patient expectation
Expectation of the patient with regard to the function and aesthetics of the prosthesis has also risen tremendously. The mere restoration of chewing efficiency is not longer sufficient. Patients expect the replacement prosthesis to not only feel like a real tooth but to look like one as well. The more the prosthesis resembles real teeth, the more difficult it is to maintain. Not all patients have the manual dexterity to use special floss to clean the hard to reach areas. Without proper maintenance, inflammation and infection may cause breakdown of the surrounding tissue.
An implant is able to withstand the load of chewing in the long run because it is “bonded” biologically with the bone. This bond is a biological process whereby the bone cells grow onto the implant surface and deposit bone directly on it. This process can be disrupted by various factors. Bacterial infection can cause a breakdown of the bond after it is formed, just like natural teeth developing gum disease. It can also prevent the proper bonding of the bone to the implant in the healing phase. Even without extrinsic factors like bacteria, a patient with a compromised healing ability such as uncontrolled diabetes and tobacco smoking may also experience a failure of bonding. An implant that is overloaded due to an inappropriate prosthetic design can also result in a breakdown of the bone to implant bond.
Dental implants are made of pure titanium, which is not a very strong metal. In some cases, overloading of the implant coupled with loss of bone support may result in fracture of the implant. This will result in not just having to replace the fractured implant but the prosthesis that it supports. Fortunately, this is relatively rare. More commonly, mechanical problems arise in the prosthetic components. The dental prosthesis is connected to the implants by small screws. If the force distribution is uneven, or if the angulation of the implants result in a non-axial loading of these screws, they may break and that will result in a loose prosthesis.
The ultimate purpose of an implant is to support a prosthetic tooth. In order to achieve that aim, the implant must be placed in the correct position and angulation. Sometimes, an implant is placed in such a way that it is not possible to fix a functional prosthesis onto it.
An implant can achieve biologic, mechanical and functional success but yet be deemed as a failure to the patient if the aesthetics does not pass muster. In fact, this is one of the most difficult problems to solve. An implant that is successfully integrated in bone cannot be removed easily. Removal of the implant often requires removal of the bone around the implant. In the aesthetic zone, i.e. the front teeth, bone is usually scarce and removal may result in insufficient residual bone for repeat implantation. Extensive bone grafting and soft tissue grafting may then be needed before a new implant can be placed.
The old dictum that “prevention is better than cure” applies. It is far better to spend time during the consultation process to understand what is achievable and what is not. Sometimes, the patient has very different idea of the outcome than the dentist. The common assumption amongst dentists is that most patients want to simplify treatment and reduce cost. While that may be true, patients should know what such measures are compromising. For example, restoring a fully edentulous upper jaw with a prosthesis supported by four angulated implants without bone grafting makes the treatment simpler and cheaper. However, such a treatment plan has no room for contingency. If one of the implants fails a year later, the entire prosthesis will need to be replaced. It is alright to do this but the patient needs to understand and accept the risk.
Planning for failures
Patients and dentist alike need to acknowledge that the practice of implant dentistry is not an exact science. Studies have shown a high success rate but like what our local police advertisement says, low failure does not mean no failure. Even if the success rate is 99%, to that 1% who experience the failure, it is 100%. It is not always possible to predict who will be in that 1%. As such, we need to plan for contingency. Engineers build redundancy into their planning. If there is a power failure, the emergency system kicks in and life goes on as per normal while the failed system is being repaired. Buildings are built with supporting structures that far exceed the minimal requirement for the stated load to ensure safety. In many ways, reconstructing lost dentition with a prosthesis is similar to engineering. The plan must include a contingency for failure and complications. While adding redundancy into the plan drives up the cost, not having it will result in greater cost in the event of a failure.
Management of the complications
In most cases, a problematic implant is best treated by removing it and starting afresh. If it is a biological problem, i.e. the implant failing to integrate or a breakdown of an integration, removal is easily done by reversing the implant out. However, if the implant has fractured or has integrated but in a non-functional or non-aesthetic position, removal is more invasive.
Re-treatment needs a well-thought out plan. As an implant exists to support a prosthesis, its removal will also necessitate the removal of the prosthesis. As such, the plan must include provisions for a temporary prosthesis. Analysis of the causative factors of the failure must be done so as to eliminate or circumvent them in the design of the new prosthesis.
Some problems may be systemic in nature. Diabetes and tobacco smoking are often implicated in cases of failed integration and need to be addressed in re-treatment. Referral to an endocrinologist to manage the diabetes and a smoking cessation clinic may be needed.
Deficiency of bone quality and quantity may be to be addressed with bone augmentation procedures. In cases, where overloading is implicated, additional implants may need indicated to share out the load.
Advances in regenerative technologies and techniques have enabled successful re-treatment of many failures. However, they come at a considerable cost both in terms of finances, time and morbidity. A thorough discussion of the cost versus benefit of an ideal treatment plan is essential before commencing on complicated re-treatment.