Down to the bone – Gurvinder Bhirth

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  Posted by: The Probe      2nd May 2019

Dental implants have become a preferred treatment modality for many partially and fully edentulous patients in recent decades. Offering durable, highly functional and aesthetically favourable results, dental implants are as close as we can get to offering patients a second set of permanent teeth.

One key advantage of a dental implant is that functionally, it closely approximates a natural tooth, so the underlying bone structure will be subject to similar levels of stress. Evolution has shaped our bodies to be conservative, operating on what is essentially a “use it, or lose it” principal. Where bone is under less, or no strain, the body remodels it, reducing its strength. This is why astronauts operating in microgravity lose on average approximately 2% of their bone density every month (with some being observed to lose nearly a third of their bone strength within 6 months), despite maintaining an exercise regimen designed to minimise the effect.[1]On a more localised scale this occurs in the mouths of partially and fully edentulous patients, resulting in resorption – particularly in the mandible where the effect can be four times that seen in the maxilla. This in turn, alters the soft tissues causing functional and aesthetic changes (though there are other factors beyond the absence of mechanical strain that are theorised to play a role in these changes).[2][3]

However, while an implant can arrest resorption, there are numerous conditions that can leave the patient with insufficient or poor quality bone at the surgical site, preventing them from receiving the treatment in the first place. Atrophy, periodontal disease, cancer, physical trauma and other factors can all result in degeneration and destruction of the tissue, making suitable implant placement impossible without additional volume.[4]

Thankfully, human bone has some of the best regenerative properties of any of our bodily tissues (perhaps matched only by the liver). Unlike other structures (such as tooth enamel), bone can often heal to a level that is functionally indistinguishable from its pre-injured state.[5]Even where the body cannot fully heal itself its regenerative ability enables bone grafting, which in implant dentistry, can be utilised to compensate for physiological conditions that would otherwise be a contraindication to treatment.

The material for a bone graft doesn’t necessarily have to come from the patient – there are four categories from which material can be sourced. Bone tissue from patients themselves (known as an autograft), bone from other donors (allografts), non-human sources including bovine or porcine bone (xenografts) and synthetic materials such as bioreactive glasses and calcium phosphates (alloplasts).

Autografts are considered to have the greatest osteogenic potential, meaning more new bone cells are likely to be created following such a procedure, which can aid healing and long term success.[6],[7]

Grafts from extraoral donor sites are entirely feasible, though there is less morbidity associated with intraoral donor sites making that the preferred option where possible. Limited suitable donor material and the secondary surgery required can make other graft sources preferable, or even necessary. Xenogenic bone can be used with or without autogenous bone, and has the advantage of being widely available.[8]Synthetic materials are likewise not subject to scarcity.

Many patients have concerns over infections and prion diseases being passed to them through graft tissue, perhaps particularly so in the UK due to the shadow of Bovine spongiform encephalopathy (commonly referred to as Mad Cow Disease). However, while it is theoretically possible for a prion to be transmitted through an allograft or xenograft, the bone tissue used for grafts is thoroughly sterilised, a process which should ensure any potentially infectious protein is removed. All currently available bone grafting material is considered to be safe and reliable, and no prion transmission has been recorded.[9]

While the biomaterials used for grafts are extremely safe, opportunistic infections from implants are a rare but potentially serious complication (especially against a background of rising antibiotic resistance). It is possible for a biofilm to form between the implant and patient tissue, impairing the bond and providing a haven for bacteria that is difficult treat. Following this, implants can potentially become infected too, including synthetics. While antibiotics are still effective within artificial graft materials, the particular bone substitute used can influence their performance.[10]

Cases requiring bone grafts can be very complex, requiring experienced clinicians to properly assess, plan and execute treatment. BPI Dental has experts well versed in bone augmentation procedures, and it offers a full patient referral service. Even where a graft would not be viable for a particular patient, implants placed into the zygomatic bone are a possibility. This is an advanced alternative that the experts at BPI Dental can also provide.

Bone grafts may sound intimidating, but with sound treatment planning and execution they are a reliable treatment with favourable success rates that can help many patients, enabling more people than ever to benefit from dental implants.[11]

 

For more information on the referral service available from Birmingham Periodontal & Implant (BPI) Dental, visitwww.bpidental.co.uk, call 0121 427 3210 or email info@bpidental.co.uk

 

Referecnes

[1]Keyak J., Koyama A., LeBlanc A., Lu Y., Lang T. Reduction in proximal femoral strength due to long-duration spaceflight. Bone.2009; 44(3): 449-453. https://www.ncbi.nlm.nih.gov/pubmed/19100348February 8, 2019.

[2]Hansson S., Halldin A. Alveolar ridge resorption after tooth extraction: a consequence of a fundamental principle of bone physiology. Journal of Dental Biomechanics.2012; 3: 1758736012456543. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3425398/February 8, 2019.

[3]Emami E., de Souza R., Kabawat M., Feine J. The impact of edentulism on oral and general health. International Journal of Dentistry. 2013; 2013: 498305. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3664508/February 8, 2019.

[4]Chiapasco M., Casentini P., Zaniboni M. Bone augmentation procedures in implant dentistry. The International Journal of Oral & Maxillofacial Implants. 2009; 24(Suppl.): 237-259. https://www.ncbi.nlm.nih.gov/pubmed/19885448February 8, 2019.

[5]Roberts T., Rosenbaum A. Bone grafts, bone substitutes and orthobiologics: the bridge between basic science and clinical advancements in fracture healing. Organogenesis.2012; 8(4): 114-124. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3562252/February 7, 2019.

[6]Roberts T., Rosenbaum A. Bone grafts, bone substitutes and orthobiologics: the bridge between basic science and clinical advancements in fracture healing. Organogenesis.2012; 8(4): 114-124. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3562252/February 7, 2019.

[7]AlGhamdi A., Shibly O., Ciancio S. Osseous grafting part i: autografts and allografts for periodontal regeneration – a literature review. Journal of the International Academy of Periodontology. 2010; 12(2): 34-38. https://www.ncbi.nlm.nih.gov/pubmed/20465029February 7, 2019.

[8]Cha H., Kim J., Hwang J., Ahn K. Frequency of bone graft in implant surgery. Maxillofacial Plastic and Reconstructive Surgery. 2016; 38(1): 19. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4819798/February 7, 2019.

[9]Singh R., Mahesh L., Shukla S. Infections resulting from bone grafting biomaterials. International Journal of Oral Implantology and Clinical Research.2013; 4(2): 68-71. https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1708-8208.2011.00407.xFebruary 8, 2019.

[10]Geurts J., Arts J., Walenkamp G. Bone graft substitutes in active or suspected infection. Contra-indicated or not? Injury.2011; 42(suppl. 2): S82-S86. https://www.sciencedirect.com/science/article/pii/S0020138311002919February 7, 2019.

[11]Clementini M., Morlupi A., Agrestini C., Ottria L. Success rate of dental implants inserted in autologous bone graft regenerated areas: a systematic review. Oral & Implantology.2011; 4(3-4): 3-10. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3530967/February 8, 2019.


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