Dental practice in the UK in 2015/2016 – Part 3: Aspects of indirect restorations and fixed prosthodontics.

Br Dent J 2019; 226: 192–196; http://dx.doi.org/10.1038/sj.bdj.2019.95

This questionnaire-based study's focus is twofold: (i) to identify current practice in the provision of indirect restorations and fixed prostheses within UK GDPs; and (ii) to establish any changes, trends and gaps in treatment methods, techniques and materials.

Core build-up

There has been an increase in the use of light-cured resin composites but amalgam still remains most used. Interestingly, according to the authors, the use of dentine pins continues despite their limitations. In the interests of patients, advice and guidance is required on the best systems to limit tooth structure removal and to ensure retention of pulpal health.

Posts

There is a high usage of preformed posts, which have more advantages, in relation to improved retention and reliability. Fibre post usage has doubled since a 2008 study, however, the use of cast metal posts continues in certain clinical circumstances even though the Nayyar core technique may be more suitable.

Impression materials

The majority still use addition-cured silicone for its accuracy and handling properties rather than polyester impression material which requires automated mixing. There are concerns that suboptimal materials are still being used while there is little usage of digital impressions.

Fixed protheses

Since 2008, precious metal-alloy usage has declined while non-metal alternatives usage has increased. Most clinicians use glass ionomer or resin modified glass ionomer as cement while there has been a significant drop in zinc phosphate usage. Zirconia-based ceramics usage has increased but most GDPs used resin based cements with zirconia restorations, although there is still disagreement about what's best.

Anterior aesthetic restorations

Indirect veneers are used the most but increasingly, direct resin composite veneers are being used. This trend needs to feed into under/postgraduate training according to the authors. The use of 'metal-free' crowns has doubled due to patient demand, while advances in biomaterials has enabled the development of aesthetically pleasant, high-strength zirconium-based ceramics to build metal free crowns.

Conclusion

The authors concluded that there has been an increase in the use of light-cured, resin-based composites as a core build-up material while amalgam remained the preferred option. Fibre post usage has increased, however, dentine pins continue to be used. For crown and bridgework, addition cured silicone impression material is still used widely. Direct resin composite veneers are preferred as an alternative to indirect porcelain veneers. Guidance for practitioners is recommended for best-practice and optimum materials' use for improved patient outcomes.

Beth Bradley

5th Year Leeds Dental Student

Why do you think amalgam and dentine pins continue to be used, contrary to international trends?

Author Q&A with Ahmad Jum'ah Jordan University of Science & Technology

Continued use of amalgam and dentine pins may be primarily attributed to the lack of confidence and knowledge in adhesive bonding coupled possibly with a lack of understanding of the limitations of dentine pins. Amalgam is not technique sensitive and can be placed in a short time. It is associated with minimal, short-term side effects. Dentine pins are easy to insert and provide a substantial amount of retention. Adhesive cores negate the need for amalgam and dentine pins and currently available materials offer optimum retention via micromechanical/chemical bonding to tooth structure. However, adhesive cores are technically demanding, require tight moisture control and need meticulous handling to:

  • Achieve optimal bond to different tooth tissue, that is, enamel and dentine

  • Reduce polymerisation shrinkage and degradation of hybrid layer

  • Avoid adverse pulpal reactions as a result of gap formation or subsequent microleakage.

Did any of the results surprise you?

Despite the large demand on metal-free restorations, 12% of the surveyed clinicians have never prescribed them. The percentage of clinicians who experienced zirconia framework fracture was astonishing. This is one of the rarest failures that can be encountered with zirconia restorations. This may raise concerns regarding the adequacy of tooth preparation, quality of the used zirconia blanks or validity of fabrication process. It was also disappointing to find that almost one in five practitioners used inadequate impression materials for the production of indirect restorations.

What do you think the next steps should be considering your findings?

Regulatory bodies should put in place measures to ensure compliance with the amalgam phase-down plan. It is prudent to assume that it is in the best interest of patients and clinicians to encourage the use of minimally invasive treatment modalities. Simplified guidelines collating data regarding rationale, chemistry, materials and techniques involved in adhesive bonding may be urgently needed. Dental practitioners are highly encouraged to stay updated regarding current research findings and best practices.