Dentists who offer patients dental implants now have a set of guidelines to refer to.
Dental implants are small titanium screws placed into the jawbone. They are then topped by artificial teeth, such as crowns, bridges and dentures, to replace missing teeth.
These first guidelines deal with 13 grey areas, such as whether to replace diseased teeth with implants or to save them with root canal treatment, when to insert implants and artificial teeth and when to use smaller implants, called mini-implants, that are less stable than larger ones.
They were prompted by increasing variability in practice, said Dr Chan Siew Luen, an oral and maxillofacial surgeon at Mount Elizabeth Medical Centre.
Dr Chan, who is also the president of the College of Dental Surgeons, Singapore, headed the 22-man workgroup appointed by the Academy of Medicine Singapore and the Ministry of Health (MOH) in 2009 to draw up the guidelines.
Dr Chan said that dentists may rely on implant companies to provide information about their products before adopting them for clinical use.
But such commercially driven research is typically "not as rigorous as you'd like it to be", he said.
The guidelines draw on evidence-based research to provide recommendations to general dental practitioners, oral and maxillofacial surgeons, prosthodontists, periodontists and endodontists.
The team of experts took more than two years to research and draw up the 50-page guidelines, which is now available on MOH's website.
The guidelines are not enforceable by the authorities but could form the grounds for taking action against a doctor when there is a complaint to the Singapore Dental Council, the professional regulatory body for dentists.
Dentists said the guidelines are long overdue, with dental implants gaining popularity among those who have lost teeth to decay, periodontal disease or physical trauma.
People can use their compulsory medical savings account, Medisave, to offset part of the cost of implant procedures, which can set one back by $4,000 for an implant-supported crown and up to $10,000 for an implant-supported bridge.
The guidelines noted that Medisave withdrawal for dental implant and related operations last year exceeded that in 2010 by 5 per cent, which had risen by 15 per cent over the amount in 2009.
One concern, said Dr Chan, is that dentists would lean towards replacing diseased teeth with implants topped by artificial teeth, when the literature shows that teeth survive just as long with conventional root canal treatment.
Root canal treatment involves the removal of nerves and blood vessels from an infected tooth, saving it from extraction. It costs between $1,500 and $2,000 to have root canal treatment and a crown inserted by a general dental practitioner.
The guidelines said both options have similar survival rates, so the decision would have to be "based on factors other than the treatment outcomes of the procedures themselves, such as medical history, caries, patients' preference and other socio-economic factors".
In fact, said Dr David Ng, a general dental practitioner at Camden Medical Centre, if a tooth appears to be viable, he would try to persuade a patient to preserve it instead of replacing it with an implant.
Though an implant gives a patient the same biting force as a natural tooth, it does not provide the sense of pressure upon biting, which tells a person not to bite too hard so as not to fracture his crown.
One controversy is whether implant procedures should be completed over one or two sessions.
Previously, all implant procedures were completed in two procedures. mThe dentist would first surgically place tiny titanium screws into the jawbone to replace the root portion of missing teeth.
Several months later, after the screws had fused with the jawbone, the patient would have another procedure to connect the prosthetic teeth to the implants.
But some dentists now complete both steps in one sitting to make it more convenient for patients. Unfortunately, dentists are not all clear if the implants affixed in the fast-tracked procedure are as strong as those done over two sessions.
Dr Chan said the best designed study in the literature compared the two methods and reported that immediate placement had a success rate of about 92 per cent while that of the conventional method was 100 per cent.
Other less rigorous studies have indicated lower success rates of varying degrees for both procedures, he added.
The guidelines will recommend that some prostheses such as an overdenture for the upper jaw - a denture held down by attachments - not be fixed onto the implants immediately. Movements such as eating would cause the implants to move slightly and compromise their integration with one's natural bone.
Agreeing, Dr Hoo Swee Tiang, a dental surgeon at Novena Specialist Centre who was not involved in drafting the guidelines, said implant-supported overdentures, which can be removed by patients, are inherently less stable than a conventional fixed, full-arch bridge, which combines at least 10 prosthetic teeth in a single unit.
Dr Melvin Mark Chia, a dental surgeon at a private clinic at The Central, said in the meantime, patients can continue to use conventional dentures in the upper jaw which are held in place by suction against the roof of the mouth.
These dentures will sit over the implants but not exert pressure on them, he explained.
Even though dentists generally agreed that guidelines such as these are useful, checks showed that not everyone would adhere closely to the recommendations.
Dr Oliver Hennedige, a dental surgeon in private practice at Tanjong Katong, has been offering mini-implants that range from 1.8 to 3mm in diameter to patients for more than a decade. Conventional implants are typically more than 3mm in diameter.
The guidelines pointed to a "lack of clinical data regarding implants of less than 2.5mm in diameter", and recommended that they should not be used routinely. Those that are between 2.5 and 3.3mm can be used, but only to support overdentures in the lower jaw, the guidelines said. But Dr Hennedige is unfazed. He said: "Why should I change my practice if what I've been doing has been successful?"
He said fewer than 5 per cent of his patients encounter problems with their implants and the ones that do can have the implants re-inserted.
Once a conventional implant fails, however, the original site can no longer take another implant.
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