Technique tips: Ten top tips to overcome common mistakes concerning the use of dental materials

1. Read the instructions and follow them fastidiously

This is the most important tip and one that can never be repeated too often or stressed too much. Regrettably, it is one that many dentists fail to do often, or indeed, at all. On receipt of a new product, the temptation to discard the directions for use (DFU) should be resisted (Figure 1).¹ These instructions should be read thoroughly, and in full, prior to attempting to use the material. Failure to do so carries a distinct risk of misuse of the material, leading to inferior clinical performance. It should never be assumed how a material should be handled and the dental team should not be tempted to guess. Furthermore, it is considered good practice to recheck the DFU with each new batch of material in case the product has changed surreptitiously because of product development, regulatory demands or ongoing product safety. Many clinics keep a folder of DFUs in an easily accessible central location for reference by all members of the dental team (Figure 2). Responsibility for its maintenance normally lies with the staff member tasked with stock control and who should insert the DFU from the latest batch and remove the existing one.¹

2. Use bona fide products from reputable manufacturers

Mention has been made in Dental Update on more than one occasion by Editorial Director, Trevor Burke,^2,3 that dental clinicians should be wary of choosing to use own-label products because they have no scientific evidence to support their clinical performance and may vary widely between batches.^4,5,6,7 Reputable dental material manufacturing companies invest heavily in research and development to bring products to market. Their quality assurance and control are also of a high standard, so ensuring that the product will handle and perform clinically as intended, providing reassurance for the patient and dental team alike. This explains why these products tend to cost more and for dental materials, like other things in life, the user gets what they pay for. Time is the expensive commodity in clinical practice and premature failure of the material will necessitate having to repeat the procedure again, at no cost to the potentially disgruntled patient, not to mention loss of professional reputation.³ If there is an issue with any aspect of handling or clinical performance, the reputable companies will fall over themselves to help to preserve their good name, which is further reassurance for the clinician. Can the same be said about (cheaper) own-label products?

3. Think about compatibility of systems

Very commonly, the chemical constituents of materials will vary between manufacturers and even between the same generic chemicals. For example, some of the resins used to synthesize resin composite such as bis-GMA, may differ between manufacturers. This may lead to a chemical incompatibility with other products. It is wise, therefore, to adopt a consistent approach and never be tempted to mix materials/products. Furthermore, the bonding agent needs to be chemically compatible with the resin-based composite material being used. The advice, therefore, would be to use products from the same stable. In other words, if, for example, one of 3M's resin-based composite materials is being used, then a bonding agent manufactured by 3M should also be selected. Bonding agents and resin composites from the same manufacturer are designed to be used together and so will yield best results. Furthermore, using different and potentially incompatible systems will invalidate any guarantees from reputable manufacturers, and will preclude any attempt of help to overcome any issues as mentioned in Tip 2. Similarly, the curing light used in the photopolymerization of resin-containing products must be compatible with the material in terms of light output (intensity) and correct wavelength.⁸ Just because blue light is emitted from the lamp, this is no guarantee that this light is fit for purpose. The same caution should also be applied from Tip 2 with respect to purchasing good quality hardware. High-quality products from a reputable company will generally be a wise long-term investment.

4. Understand the materials you are using

The dental clinician has a responsibility to understand the materials that they are using. Failure to do so will invariably lead to inappropriate prescription, handling and usage, so leading to an inferior clinical outcome. This includes understanding their chemical constituents because this information may be used as a guide to the likely properties, indications and how the material must be handled. For example, some materials, such as the resin-based composite materials, are hydrophobic in nature and will be detrimentally affected by any moisture to which they may be exposed during clinical manipulation. Conversely, other materials, such as the hydraulic cements, require moisture in order to effect their set, and are in fact designed for use in wet environments because they do not deteriorate in use.⁹ Furthermore, if the product requires light curing, how should this be done? Incrementally perhaps, and if so, what is the maximum thickness of each increment that should be placed, and how should the material be placed in the cavity? Background information that allows the clinician to understand the material, its properties, indications and usage can be found in the DFU and other supporting literature available from the manufacturer.

5. What works well in your hands?

Dental clinicians have differing ways of working and preferences about how they like a material to handle. At postgraduate lectures, often given by charismatic speakers showcasing their (best!) work, the clinician may be influenced and so be tempted to change to the product featured in the presentation. Just because the speaker can achieve exceptional results with a product (and is the speaker sponsored by the company, therefore, are they impartial?!), it does not follow that everyone else will. If a clinician is achieving good results with a particular product, then there is no reason why they should change. However, if, for example, a resin-based composite material is too stiff or too fluid to work well in the clinician's hands, then they should consider changing to another product with which they may fare better. In short: if it ain't broke, don't fix it!

6. Work in an as ideal condition as possible

The oral cavity is a challenging environment in which to work. In the course of providing clinical care, the operator must overcome restricted access and vision, a wet environment due to the presence of liquids such as saliva and blood, and gas (humid exhaled air), not to mention the presence of micro-organisms. Furthermore, during restorative or endodontic treatment, the clinician may be using some corrosive or irritant chemicals that may damage the soft tissues or be swallowed. They may also be using small instruments that may fall into the oro-pharynx or beyond… It makes sense therefore to alleviate as many of these potential hazards as possible by creating an ideal environment, which is best achieved by the use of rubber dam (Figure 3).^10,11 This allows the clinician to handle and manipulate dental materials in their ideal state, which is especially pertinent given that many are detrimentally affected by moisture contamination. In addition, there has been a shift in recent years from materials that require mixing, in favour of those supplied in an ideal condition from the factory, in an attempt to eliminate any potential mishandling factors by the dental team. Studies have indicated improved outcomes of restorative treatment when placed under rubber dam isolation,^12,13 and its placement is considered essential during endodontic treatment according to the European Society of Endodontology.¹⁴

7. Strive for predictability

Following on from Tip 6, the clinician should select materials and techniques that will yield the most predictable and consistent results. Studying the DFU and manufacturer's promotional literature for each material will glean invaluable information to guide the clinician. Things to look out for are the presence (or not!) of error bars displayed on graphs. Error bars give an indication of scatter, and the closer together (narrower) they are, the more consistent the performance of the material will be (Figure 4).¹

Has the manufacturer quoted the Weibull modulus of the material? This is the probability of failure against applied stress and gives an indication of the dependability. This measure is used extensively in industry and engineering, with a higher figure indicating a more dependable material or component part of the system.¹

Any technique involving multiple steps is potentially more fraught with the potential of failure. Each step introduces inaccuracies, which are cumulative. With increased steps, the greater is the potential for failure. Where possible, the clinician would be wise to adopt techniques involving fewer stages, with this being especially pertinent for bonding protocols.

8. Be precise with laboratory prescriptions

Each prescribing clinician has a medico-legal obligation to design the prothesis and prescribe appropriate materials in medical devices intended for patients.^15,16 This is often overlooked, especially with respect to the prescription of alloys and ceramics. There may be many clinical reasons why a specific alloy is chosen, for example a non-precious alloy may be selected if the restoration is to be bonded to dental hard tissues, or if, perhaps, limited interocclusal clearance is present. White alloys are similar with respect to appearance, yet have very different properties and indications. Should there be an issue or complaint, then the component materials of the prosthesis may be analysed. If the prescription to the laboratory is clear, and an incorrect material has been used, then the dentist is absolved of any responsibility and any potential liability rests with the dental technician. The mechanical properties of the materials should be considered. For example, if strength is required and a ceramic material is desirable, then monolithic zirconia may be the material of choice, whereas if there is a requirement to bond the ceramic to dental hard tissue, then a material with a glass phase, such as lithium disilicate, would be chosen.

9. Work as a team

Team works! It makes sense to rationalize and consolidate the products that are held at the clinic. There is nothing to be gained from having, for example, four different resin composite kits, especially when they may require four different bonding systems. (At the time of writing, the price of dental bonding agents is £9540 per pint or £16,788 per litre!) Furthermore, some products may have more than one indication, further reducing the amount of stock that needs to be held. The choice of materials stocked in the clinic may be discussed at team meetings, with co-operation among colleagues saving the clinic a great deal of money. These meetings may also serve as an excellent opportunity to train all members of the dental team in the clinical handling and usage of every material held in the clinic.

10. And… Read the instructions and follow them fastidiously

Has this been mentioned before? Of course it has because it is really so important!

Conclusion

Attention to following the foregoing points will improve the clinical performance of dental materials and biomaterials and, therefore, the treatment outcome for the patient.