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Dental implants have been around since ancient times, but new teeth can also fall out

Smiling now… Implants by Shutterstock

People usually lose their adult teeth because of neglect or a lifestyle or environment that places them at high risk of decay or destructive gum disease. While high-sugar diets can lead to tooth decay, genetics can also increase the risk of bad gum disease, as does smoking and poor glucose control in diabetes patients. If you combine these with inadequate oral hygiene then tooth loss is a real possibility.

Destructive gum disease (or periodontal disease as it’s known in dental circles) is the leading cause of tooth loss and is the most common chronic inflammatory disease in humans and almost 50% of the world’s population suffer from periodontitis, where the gums pull away from the teeth and form spaces that become infected and bacterial toxins and the immune system break down the bone and tissue system supporting the teeth.

Replacing lost natural teeth with prosthetic implants secured into the jaw bone is one way to overcome the problem of losing teeth. However, as an NHS consultant who has had to salvage implants that have failed, they may not be the perfect answer you imagine.

Ancient implants

Screw-in teeth are not a feat of modern dentistry. Archaeological evidence suggests the ancient Chinese used bamboo pegs to replace lost teeth. The purpose of these early implants was much the same as today – to restore an aesthetic smile (in life or after death perhaps) – but rather than being made from titanium they were fabricated from other materials. Dental implants have also been dated back to the Maya in 600 AD. Ancient Egyptian and Celtic remains have revealed precious metals, ivory and even other human teeth used in their implants.

A landmark discovery in the bio-engineering of dental implants came in 1952 when Per-Ingvar Brånemark, a Swedish orthopaedic surgeon studying the biology of bone healing, discovered that he was unable to remove implants of pure titanium cylinders that appeared to have integrated with the surrounding bone after healing. The titanium seemed to attract bone formation onto its surface and the term osseo-integration was born.

By the 1960s there was a desire for fixed replacements that were embedded into the jaws, rather than traditional bridges or dentures that sat on the surface. In 1967 “Blade Vent” implants became popular, but with mixed success. These were metal blades that were implanted into the jaw bone and healed with a fibrous capsule between the metal implant and the investing bone. It meant that they were not completely immobile, not truly integrated with the bone and prone to infection, inflammation and implant loss.

It wasn’t until 1981, after 30 years of meticulous research and human studies that Brånemark published his findings and modern implants as we know them were born. The first Brånemark implants were produced as parallel cylinders of titanium which had an external screw thread, so they could literally be “screwed into” the bone. A second generation of meticulously engineered “self-tapping” cylindrical implants appeared in the early 1990s.

Their placement was facilitated by a five-drill bit set with bespoke surgical instruments, along with cover screws, torquing wrenches and all manner of equipment, designed to provide a surgical procedure that no well-trained surgeon could fail to follow. It was essential to attend manufacturer-run training days and become certified to place these implants. In return each implant was guaranteed and replaced free of charge if it failed.

Changing landscape

Over the next decade competitor systems emerged. While some were well researched and manufactured, others were poorly conceived and doomed to create misery for increasingly demanding patients who wanted fast replacements and were prepared to pay obscene amounts of money. Travelling abroad for affordable implants, with no guarantee of any after care, became increasingly an option.

Say cheese. Matt Janicki, CC BY

Manufacturers took risks, patients became more demanding, standards fell and the General Dental Council decided not to create a specialist list of trained and accredited implant surgeons. Now there are more than 500 different types of implant available. Patients can be ill-advised, completely unsuited to particular systems or they may simply ignore advice/warnings to travel abroad for “holiday implant surgery”.

The irony

The irony is, however, that dental implants are most likely to fail for the same reasons the teeth were lost in the first place. Implants are far harder to clean than natural teeth due to their narrow cylindrical shape and because the bone grows directly onto the implant surface they lack a periodontal ligament, which provides stem cells and healing proteins that can delay or help resolve inflammation. So if this inflammation starts the implants begin to lose their attachment to the bone. This can be relentless until the implants literally fall out.

The success rates of the original Brånemark implants were 95%-98% over three decades. However, designs changed to satisfy an increasingly demanding market place have changed our definitions of “failure”. Today, a quarter of patients with implants will experience failure of one or more implants within ten to 12 years.

CT scan in ready for dental implants. Jeffrey Dorfman, CC BY-NC-SA

Failure was originally defined as “loss of implant”. However, modern implants support a bridge or denture, and loss of one implant likely means loss of the bridge or denture, so the “proportion of patients who have lost one or more implants” was deemed a more appropriate definition of “failure” meaning a rise in failure rates to 11-12%. After another redefinition of failure as a “progressive loss of bone” around the implant the failure rate rose again to 22-25%. Moreover, the proportion with the early signs of inflammation around their implant – peri-implant mucositis – was 46%.

More importantly, studies have demonstrated that “periodontally hopeless” teeth over a 15-year period out-survive newly-placed dental implants, and protracted treatment to retain molar teeth most severely affected by periodontitis was more cost effective and successful in terms of “tooth survival” than newly placed implants.

So if retaining teeth is possible, it is significantly preferable to extracting them and replacing with an implant. If planned carefully, placed well and maintained very carefully, implants are still an excellent treatment for missing teeth. However, for patients who have lost teeth to gum disease, who have gum disease, who smoke or who struggle to control their oral hygiene, or for that matter their diabetes, dental implants are a high-risk and high-cost option that may end in tears.

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