Barts and The London School of Medicine and Dentistry

Fracture and Wear of Dental Restorations

Summary

Novel low-wear, high-strength glass-ceramics were developed at Barts and the London School of Medicine and Dentistry in 2000-2011 by Dr Cattell’s team to prevent facture and wear of dental ceramic restorations. Over three million restorations have been provided for patients and sold in 46 countries. The product uses a 100% pain-free minimally invasive approach, saving as much as 20% enamel reduction per patient, as tooth preparation and anaesthesia are not required. We also estimate a substantial reduction in tooth enamel wear of 43-46% for this nano-scale product compared to commercial porcelain. It has high patient acceptance and satisfaction.

The science: developing leucite glass ceramics for use in dental restorations

Dr Cattell, from Queen Mary’s Institute of Dentistry, undertook this research (2000-2011) with his team to address problems encountered in clinical dentistry, particularly in general practice, with brittle fracture of porcelain restorations and their poor survival rates over ten years (crowns = 52% and veneers = 47%) and substantial costs (£117.5M and £6.5M respectively).

Dr Cattell conducted the fundamental work on leucite glass-ceramics. Processing of these leucite glass-ceramics using heat extrusion to produce dental restorations led to an even distribution of fine crystallites and increases in tested reliability and strength compared with current materials. During this work he discovered a process of controlling the leucite crystal size in glass. His team discovered that control of the chemical and physical properties of the glass, together with crystallite size, were key to enhancing the properties of the glass-ceramic. They also demonstrated efficient adhesive bonding of these materials and further surface strengthening. These studies were critical to reducing the size of the abrasive leucite crystals that had enormous benefits in terms of reduced enamel wear, improved aesthetics and increased strength. The resulting material was adopted as an aesthetic restorative material for clinical use. The clinical outcomes were minimally invasive dentistry, less drilling and pain for patients and prevention of crown fracture and destructive enamel wear.

Putting research into action: impact on oral healthcare

Over three million dental restorations have been manufactured and placed for patients using these highly successful glass-ceramics. It is now a global product sold in 46 countries including: The Americas, Europe, Asia Pacific, Middle East and Africa.

These unique high-strength glass-ceramics allow minimal or “no tooth” drilling and eliminate the associated pain, discomfort, and local anaesthesia injections (by up to 100%) required to prepare teeth. This also means 100% reduction in postoperative patient pain, less tooth destruction (20% less) and fewer or no provisional restorations. High aesthetics combined with a pain-free minimally invasive tooth preparation approach has led to high patient acceptance and satisfaction with this product. Another major benefit of the leucite glass-ceramics is dramatically reduced enamel wear properties. Many conventional porcelains/ceramics are destructive to tooth and in the UK 8-10% of the population are affected by tooth wear. The current materials have the opposite effect and will be kinder to tooth structure. We estimate that they will give a staggering reduction in tooth enamel wear of 43-46% compared to other commercial porcelain. This is of great benefit to patients to reduce tooth destruction, pain and the prevention of more complex dental treatment, such as costly bridges and implants when worn teeth are difficult to restore.

A patient said: “The process was amazing – it was almost too easy! No shots, drilling or pain. I love how natural they look and feel. Who knew getting a new beautiful smile could be so easy.” A dentist said: “Tremendous benefits for all our patients because of the no shots or temporaries. It produces a tremendous smile with very little or no discomfort to the patient.”