International relief organisation, Bridge2Aid, which provides emergency dental treatment to some of the world’s poorest people, launched its Australian arm at a private event hosted by ADA NSW Centre for Professional Development at St Leonards on October 11.
By Chris Hussey
Dental Ceramist / Sirona CADCAM Key Opinion Leader Ceramic Studio
There are a plethora of factors that influence the final aesthetic of a crown and bridge restoration, hence your patient’s satisfaction. The unfortunate fact remains that, no matter how brilliant your clinical work is, your patient will usually only care about what they can see at the end of the day. If the central crown they have saved for is too opacious, too stark, too dark or, in some cases, too idealistic when compared to their natural teeth, then today’s discerning consumer is likely to let you know about it.
In this article I will discuss how to achieve the best aesthetic result possible for your patient should shade-taking be conducted in-house. In so doing, it is imperative to discuss key considerations, including:
- Shade guides
- Communicating with your technician
- The preparation, materials and translucency
- The stump shade
- Laboratory shade-taking
- Human limitations
- Shade Guides
Shade guides are obviously your primary reference tool to communicate with your technician. Many clinicians are accustomed to using the VITA Classical A-D shade guide but may be somewhat reluctant to pick up the VITA System 3D-MASTER guide (the 3D system). I am given the impression that this is usually due to lack of familiarity with how it works.
I am certainly not against the A-D system, however it is somewhat limited and can be easily misinterpreted. What I mean by this is that some groups have a wildcard that seemingly has no place amongst its peers. For example, group A’s chromatic scale consistently increases until it reaches A4, which has nothing to do with A1- A3.5. A4 suddenly introduces grey and a significantly deeper value of red. In fact, I would argue that it would be more suited to group D (reddish-greys) than group A.
Furthermore, we are seeing more and more patients with bleached teeth. This revelation is casting the A-D system into yesteryear as the lightest it goes is B1, which is a very yellowish colour, not suited to the glamorous amongst us.
Mastering the 3D system can be highly useful, particularly if you are requesting an anterior restoration. The art of balancing particular hues can lead to the aesthetic success or otherwise of your restoration. In my experience, these are grey, red and yellow. I still find it amazing how a crown may suddenly “disappear” when a particular blend of grey is applied during a follow-up shade consultation with a patient.
The 3D system is a fantastic tool to help you identify such hues in your patient’s natural dentition. VITA have designed the guide so that one first selects the apt group. In the middle of groups 2-4 are “balanced” tabs which are first compared to the subject teeth. On so doing, the question of whether or not the patient shows more red or yellow may start to become more apparent. If you think more red is necessary, go to the tabs to the right. If you think more yellow is necessary, go to the tabs to the left.
Identifying greyness is a little trickier. As a rule, groups four and five are the “grey shades”, however grey comes in to play in certain tabs in the O’s, 1’s, 2’s and 3’s. 1M1 for example is a reddish, greyish, creamy shade. 3M1 is also quite grey. My point being is that when you first look at your patient and believe him or her to have somewhat grey teeth, it may be prudent not to immediately jump to group four but to consider lighter groups if appropriate. Instructions on how to use the 3D system can be found at vident.com.
It is true that as one becomes more familiar with the 3D system, one will start to go immediately to a given shade tab, however it is probably good practice to follow the suggested steps until such time (remember when Neo first stopped the bullets in The Matrix…). A systematic approach will aid in reducing the chance of the incorrect shade being selected due to the mind’s belief overruling the eye’s account. I will discuss this further on. Guides are what they are: guides.
What I mean by this is that your patient’s natural teeth may not correspond to any of the tabs. In fact, this is commonplace. There should however be the closest tab. Once this base reference is identified, there is nothing stopping the clinician from exploring further. For example, one may request a “4M1 but with a little less red”. If you have a want, your technician will likely have their own techniques for providing.
Painting the Picture for Your Technician
It is not an overstatement to compare natural teeth to the works of masters of colour such as Renoir or Turner. The more you look at them, the more you see, not unlike gazing into a polished opal. In filling out a lab ticket for your technician, what you are effectively doing is describing a unique masterpiece to a blind person.
One of the first lessons I was taught when studying fine art ended up being the most important lesson of all; “transpose what you see, not what you believe you see, nor what your prejudice imposes upon you.” This approach will ensure that you do not miss all the perfect imperfections that make a tooth real. First year art students are often instructed to practice sketching whilst only looking at their subject and not their canvas. The same approach can be applied to shade taking: what is it that you really see?
With this philosophy in mind, one still needs a practical approach to recording such information chairside. This can effectively be achieved by dissecting the desired restoration. During an initial shade consultation, I commonly adopt the below systematic approach.
Middle: Obtain a base by selecting the very middle colour without being too heavily influenced by the cervical area.
Cervical: Select the appropriate shade for the cervical area, noting whether it is for the cervical half, third, quarter, fifth, etc. Also taking note whether this is a gradual or sudden blend with the middle shade. If the root is to be exposed, what shade should it be?
Interproximal: This can sometimes be quite important so you may also wish to sketch where it is required and in what shade.
Incisal: Does the incisal edge exhibit a bluish or greyish translucency, or a combination thereof? Does the middle colour run straight to the incisal?
Occlusal: Does the patient have any fissure staining? Is it brownish, yellowish, etc.? If wear facets are applicable, what shade do they exhibit in their centre?
Special characterisations: Is fluorosis present? If so, where? Would incorporating age cracks or striations aid in concealing the restoration? If so, consider where they should run from and to, how many would be ideal and describe their colouration (i.e. yellow, brown, reddish-brown, etc.).
Translucency (discussed further below). With this method it is worth considering taking the time to look away, and/or closing your eyes between each stage for the purposes of “allowing your eyes to adjust”, so to speak. I will explain why later on.
Preparations, Materials and Translucency
Optimal shades are the child of optimal preparations. Insufficient reduction will often provide for a lifeless restoration. I will not go into the age-long debate between clinician and technician regarding reduction, however I am comfortable in affirming that the preparation thicknesses suggested by material manufacturers are critical to the success of the overall aesthetic.
There is no end to a technician’s greediness towards a large healthy shoulder and generous occlusal reduction. This enables us to manufacture a crown with enough ceramic material to allow for an accurate shade, as well as the obvious considerations such as strength and more attractive morphology. Crowns tapering towards a feather-edge margin will start to lose their lustre towards the cervical. That said, I acknowledge that a dentist can only give what they can in some instances. Where sufficient clearance is just not possible, zirconia can sometimes be a saviour. In brief, zirconia products are categorised as layered, translucent monolithic or layered translucent monolithic. Layered zirconia comprises of an opacious coping on which porcelain is applied, much like a PFM. Many, including myself, would argue that these have more “life” than a PFM and can serve to block out a dark preparation quite well (unless the coping is very thin).
Translucent zirconia is very much its namesake. Although the translucency is very impressive for a product of such incredible mass, do not expect the lustre of a glass ceramic. It can be your best friend in the posterior region however. Porcelain can be applied to translucent zirconia to provide for hybrid designs. This way all biting forces can be exerted on monolithic zirconia yet the restoration can be enhanced by facial porcelain layering that remains passive. This is fast becoming the most popular option for bridge cases.
I have found that few clinicians I have spoken with are aware that their favourite glass ceramics, such as IPS e.max® and VITA Suprinity®, are available in high or low/moderate translucencies. This can be quite important in achieving the best result for some cases. Sometimes it is obvious whether your patient’s natural teeth have a high or low opacity, however there are other points to consider as far as translucency goes.
Low translucency might be requested in instances where you are unable to afford your technician the optimal labial reduction, or your patient may have a particularly dark preparation. In instances where this is the case, however it is critical to have a translucent incisal edge, you may consider requesting a cut-back restoration. This is where the majority of the crown is monolithic, yet the incisal third is reduced for porcelain layering.
If you are looking to marry a modern restoration with existing old ones, there is an option. A few of our clients have provided feedback to suggest that a low translucency VITA Suprinity® can blend in very well adjacent to old and tired looking PFMs, yet still look significantly more natural.
High translucency glass ceramics can look very natural indeed. This option will serve you well as a “bread-and-butter” for want of a better phrase. If you want to bring a (positive) tear to your patient’s eye when fitting your next multiple upper anterior case, I would strongly suggest this choice. High translucency crowns provide for a stunning aesthetic, hence that wow factor that will motivate your patient rave about you on social media.
For further information regarding preparation thicknesses for your preferred material, please contact our laboratory so we can mail you a clinical guide. I find the IPS e.max® Clinical Guide to be very comprehensive and provides answers to many of the questions I am asked regarding glass ceramics.
Don’t Forget the Stump
The stump shade can dramatically affect the shade of the fitted crown. Without a stump shade your technician is flying blind when staining your restoration. When you take the patient’s shade, it is done against existing teeth or fitted restorations with their own uniquely coloured substructures. It stands to reason that the case is likely to be more successful with this reference.
Your technician is likely to have a “stump shade kit” of sorts. These kits contain a light-curing composite that the technician uses to manufacture an artificial die from the shade selected by the dentist. Clever isn’t it? We like to use VITA SIMULATE Preparation Material which allows us to create a die from six different 3D system shades.
Of course if time and geography permits, you may opt for your technician to take the shade. There is merit in having the person who manufactures the restoration gaining an overall appreciation of the natural dentition. Technicians have an unfair advantage in being having to deal with the subtleties of shades and special characterisations on a daily basis.
It is best practice for a patient to attend the lab for two consultations before issue. The initial consultation will allow the technician to take the relevant information to take the restoration to an almost-finished state that is usually unglazed. We have found that some patients tend to communicate more openly about any particular anxieties or desires concerning their work with us as technicians as opposed to their dentist, despite how approachable they may be. We often hear phrases such as, “I didn’t want to bother Dr-so-and-so…” before sharing a wealth of bottled-up thoughts. After all, the very environment of the average practice is not conducive to the shy from opening up. One is generally whisked into a sanitised room and promptly laid horizontal before another’s hands are placed within the mouth. A slower and more vertical experience with a person without an intimidating title may be more conducive to a patient opening up.
A follow-up appointment will afford your technician the opportunity to make all those minor alterations that make a crown disappear if required. It is highly recommended that the patient first attend the practice to have the temporary restoration loosened or removed prior to attending this appointment.
Although it may seem somewhat disruptive to your patient to request that they attend the lab twice, we are often told of how impressed they are that the dentist and technician alike are paying so much interest in their work. The correct result may mean more to them than they let on (yes I am referring to the tough guys out there!).
Furthermore, it is a good opportunity for the technician to explain the advantages of the chosen material. Patients are also often excited to see crowns being computer-designed and milled or porcelain being applied. It can be a great way of adding value to the consumer experience at no extra cost.
It is true that your beliefs and memories play a significant role in how your brain interprets what is seen. An appreciation of this is very important when taking shades.
When comparing your shade tab against natural teeth, after a while it can be possible for you to actually start to believe that your selection is correct although it may be far too light or yellow, etc. If your eyes have been alternating between the shade tab and the teeth for an extended period of time, taking the time to look away and/or closing your eyes for a few seconds before looking back again can pay dividends.
Beware of chromatic induction. This is a phenomenon whereby the colour appearance of light is altered by introducing a second surrounding field (Shevell and Wei, 2000). It is worth bearing-inmind that grey can appear reddish or greenish when viewed within a green or red surround respectively (DeValois and Webster, 2011).
Yes, you’ve guessed it, what I am on about is lipstick or naturally deep red lips. This could cause one to incorrectly select the tabs to the right of groups two, three and four in some cases. I have created an example of chromatic inception below to show how significant this effect can be. You may be surprised to learn that the circles are all the same shades of grey, yet they appear quite different. Knowledge of any colourblindness is also important. This is undoubtedly the most sensitive topic to discuss. Between 7-10% of males on average are red-green colour blind. It may not be the end of the world if you fall into this category. It may be worth asking your dental assistant to play a more active role in shade taking. The adjacent link is to an Ishihara colour test if you are in doubt.
I realise that some of what was discussed within this article may be old news to some, yet I hope you may have taken away something from it. I am always happy to chat about material selections for your upcoming cases, or anything else should you wish to do so. The tech-savvy can find me on LinkedIn.
Complacency is an easy habit to acquire but a big liability when something serious goes wrong.
By Merv Saultry, Managing Director of Dental Innovations.
Last month a dentist contacted me and said that due to a chronic injury he had to cease work. He was devastated that he could no longer practice the profession he loved and he had to face life without an earnings income. Not only that, he had to face the reality of just how effective his risk prevention actions were.
He went on to tell me that he had always complained about the cost of his insurance portfolio and how he tried to manage the cost down while still protecting himself. His annual premium cost was always seen as an imposition and loss of income, however he decided to pay the cost to protect his current assets and protect his family’s future.
He said it was a scary process as he contacted various insurers to report his circumstances and await their responses that would determine his and his family’s future lifestyle. The stress he underwent did little to help his rehabilitation.
It turned out he had made some wise decisions and despite the annual concern about insurance costs, he had paid the money as trade off against risk minimisation. He had the normal insurance portfolio of PI and Income protection, Property Insurance plus he had Business Expenses insurance. He also benefited by having a good insurance broker who guided him to good insurance companies that had a proven history of fair dealing when it came to claims.
His medical reports determined his permanent disability insurance payout which provided him with some peace of mind but it was his Business Expenses Insurance that really paid off. There was an extended period of time before he could find a suitable locum to work while his long-term future was determined. Employing a locum covered his overheads but not his previous profit earnings. Then there was another extended period when having made the decision to sell his high end practice he tried to find a buyer at a fair price. He could have easily been facing a severe capital loss just at the time when his future income earning capacity had been taken away.
When the claims process was settled it was a great relief to find out that not only did he have a secure future disability income, he also had a large compensation payout from his Business Expenses Insurance and the proceeds of a satisfactory sale of his practice.
It could have been so very different. Through Dental Innovations’ long association with the Dental Insurance Specialist company Dental Essentials, we have witnessed many different outcomes to the above circumstances.
Dentists have traditionally used many insurance companies and brokers with the aim of cutting costs and when serious circumstances arise we hear many distress stories and the allocation of blame to the insurance broker used. The reality is that there is a shared blame because of the profit driven focus of the broker and the cost containment focus of the dentist. Dentists cannot be complacent when it comes to Risk Management. It takes years to accumulate wealth and secure a comfortable retirement and as you get older you lose the option of extended time to recover from a severe loss. This is especially applicable today when many dentists retire expecting to maintain their previous lifestyle and find their retirement income has failed to meet expectations so they find themselves having to look for locum work.
Your circumstances could change in an instant but definitely will change with time and our advice is for dentists to have a detailed review of every one of their insurances at least every 5 years by an experienced broker with proven integrity and high service level.
Your business is not the same now as it was five years ago which means your risk exposure has changed and needs to be reassessed by a fully independent experienced broker who can offer good advice and a full market range of insurance options.
The message is that it is a false economy to underinsure to lower costs as the downside risk is out of all proportion to the scale of assumed savings when events happen.
By Dr Sanzio Marques
The 32-year-old female patient presented at our dental practice complaining of painful sensitivity in certain teeth after these teeth had been treated with composite restorations. The patient stated that she had last undergone dental treatment around two years ago. The pain described by the patient did not occur spontaneously, but was predominantly provoked by chewing. Clinical and radiological examinations and the vitality test reported some composite and amalgam restorations which were visibly not sealed and displayed secondary caries. The decision was taken to renew these fillings. However, as it is not possible to make a conclusive assessment of the pulp in the case of teeth with pain symptoms, we decided on a temporary restoration of the cavity with the glass ionomer restorative IonoStar Molar (VOCO) followed by a 40-day monitoring period. Should the pain symptoms subside within this period, the cavity will be prepared again, albeit with the glass ionomer filling not being completely removed, but simply left as a base fill. A composite restoration with GrandioSO (VOCO) would then be placed. The decision to use a glass ionomer for this temporary restoration was taken based on the fact that the properties of this material make it particularly suited to this type of clinical situation. For example, we could note the excellent adhesion to the dental hard tissue, the good adaptation to the prepared tooth and the release of fluorides, which accelerates the remineralisation of the dental hard tissue affected by the caries in this case in particular. In addition, IonoStar Molar can also be used to achieve a high compressive strength, for which reason it is also recommended for the temporary restoration of the occlusal surfaces of molars.
After application of a rubber dam, the occlusal amalgam and artificial restorations on tooth 26 were removed. During cavity preparation, it was noted that the carious process had extended substantially to mesial. When examining the cavity, we decided to place a tunnel to the mesial surface. Careful removal of all the carious tissue was performed at low speed with a carbide tipped finishing bur. Following cleaning of the cavity with a 2% chlorhexidine rinse, a metal matrix was applied and wedged mesially as an aid for production of the restoration. Following activation of an IonoStar Molar (VOCO) application capsule in the shade A3, it was mixed for 10 seconds in a high-frequency capsule mixing device. This mixing time of 10 seconds allowed an appropriate working time for the size of the cavity being treated. The mixing time can be prolonged to 15 seconds to reduce the setting time of the material if required. The capsule was inserted in an applicator immediately and the material placed carefully to fill the cavity completely. It was then adapted and modelled precisely with the assistance of hand instruments such as condensers and Hollenback carvers, and any excess material removed. One notable aspect was the optimal consistency of the material on the one hand and the fact that it did not adhere to the hand instruments, which made application very easy, on the other. After a waiting period of approx. five minutes (time until the material was completely cured) the restoration was finished with a fine diamond bur, polished with the Dimanto system (VOCO) and sealed with Futurabond U (VOCO) to protect the surface. As early as the following day the patient affirmed that the pain symptoms had disappeared completely. The use of the IonoStar Molar glass ionomer proved to be so simple and practical that it will without doubt also be employed in the future in our dental practice.
With x-tra base, VOCO presents a new flowable composite, designed especially for the bulk filling technique. This flowable, self-levelling composite enables up to 4 millimetre thick increments to be laid, which can then be light-cured especially quickly; and this in just one step and without time-consuming layering. A 4 millimetre increment of x-tra base in the shade ‘Universal’, for example, requires only 10 seconds of light-curing, and thereby only half of the time required for comparable products from other manufacturers. After the insertion and polymerisation of x-tra base, the stable restoration base requires only an occlusal covering layer with a methacrylate-based universal or posterior tooth composite. This enables an equally simple, efficient and safe restorative treatment in the posterior tooth area. x-tra base is suitable for lining Class I and II cavities, as well as for the first layer of cavity lining in Class I and II cavities.
Lining materials must satisfy great demands with regard to their stability. x-tra base is characterised by high compressive strength (350 MPa) and flexural strength (133 MPa). Due to a particularly high filler content for this material class of 75% by weight and the special resin matrix, x-tra base displays only very low shrinkage and distinctly reduced shrinkage stress. This ensures a reliable adhesive bond and the long-term success of the restoration treatment. x-tra base displays perfect flow behaviour, assuring excellent adaptation to the cavity walls. This flowable composite can be combined with all methacrylate-based bonds and composites and, at 350% Al, exhibits high radiopacity. x-tra base is available both in the non-run, non-drip NDT® syringe, and in convenient flow caps with flexible metal cannula. Both syringes and caps enable secure and precise application. x-tra base is supplied in the shades Universal and A2.
Dr. med. dent. Ludwig Hermeler, Rheine, Germany
Temporary restorations play an important role in the fabrication of fixed prostheses. Whilst for dentists the focus is firmly on protecting the prepared teeth and ensuring good fracture-resistant strength, patients increasingly expect temporary restorations to satisfy aesthetic demands and to also have a surface quality that is pleasant to the touch. VOCO has now developed an enhanced self-curing composite for the fabrication of crowns and bridges. Based on VOCO’s own nano-hybrid technology, Structur 3 sets a new standard in three important are as: handling, aesthetics and durability.
The 1:1 cartridge system, containing either a 50 ml cartridge or a 5 ml QuickMix syringe, guarantees homogeneous mixing and uniform curing. It is thus the ideal choice for ensuring error-free and simple application, just like Structur 2 and Structur Premium. The patient-friendly intraoral curing time of 45 seconds is considerably shorter than with comparable competitor products. Heat generation during polymerisation is a key handling parameter. Materials which generate a temperature of 41°C during curing pose the risk of devitalisation due to denaturing. The measurements conducted by Dr. Borchers in his study “Temperature rises in the pulp of prepared teeth when curing temporary restorations made from various composites” at Hanover Medical School (MHH) show that pulpal overheating is not possible with Structur 3 . Compared to the other materials, Structur 3 produces the smallest rise in pulp temperature during intraoral curing. Finishing of the edges can begin just four minutes after the start of mixing, and the only prior step required is to wipe away the inhibition layer, formed by oxygen, using a cloth soaked in alcohol in order to achieve a lustrous shine. The study by Fleming concluded that, amongst other things, Structur 3 has the least surface roughness after removal of the inhibition layer compared to the main competitor materials on the market . Timeconsuming polishing of the Structur 3 surface is not required; so finishing time is reduced even further.
The smoother surface, as demonstrated in the above study, means that patients can remove plaque more easily, so the temporary restoration resists discoloration and remains aesthetically pleasing for longer. The fluorescence of Structur 3 has been adapted to that of human teeth, which further contributes to the optimal appearance of the temporary restoration. A selection of 8 shades enables precise adjustment to the patient’s natural tooth shade.
Fractures in temporary restorations are unpleasant for patients, while for the dental practice, the repair or refabrication of temporary restorations costs time and money. The physical parameters of the materials used for temporary crowns and bridges, including long-term temporaries, must enable them to reliably withstand daily masticatory loads over an extended period of time. In a study at the University of Regensburg , temporary crowns were produced from a variety of materials and their fracture resistance was tested. The study demonstrated that Structur 3 has the highest degree of fracture resistance. With a compressive strength in excess of 500 MPa (based on ISO 9917), efficient fracture resistance is assured.
Anterior trauma suffered by a 57-year-old patient caused the ceramic veneer of her bridge to fracture extensively in several places in the region 13 to 23 (upper canine to upper canine). It was initially restored directly with a composite after the accident. Prior to fabrication of the new restoration, an alginate impression is taken, which serves as the negative mould for the Structur 3 restoration after removal of the bridge and post-preparation. In the past, when making temporary restorations from less resilient materials, our dental practice used to take silicone impressions for the fabrication of the temporary crowns and bridges. These impressions were kept for later use in repair or refabrication in the all-too-frequent event of damage. Since switching to Structur 3, this is no longer necessary, based on our good experience with this material. The alginate impression filled with Structur 3 is reinserted. After 45 seconds of intraoral curing, the material is still slightly elastic and can be easily removed from the stumps. 4 minutes after the start of mixing, the temporary restoration has cured sufficiently to be finished. The inhibition layer is wiped away with a cloth soaked in alcohol, and a lustrous shine is already visible. The bulk of the excess material can be removed with crown scissors and rotary instruments. Interdental finishing is important for ensuring that the temporary restoration can be kept hygienic. After rough finishing, the fit is checked intraorally. The result after polishing the nanohybrid surface, preceded by finishing with rotary instruments, is indeed both highly aesthetic and functional and, at the same time, the finishing time has also been noticeably reduced. The smooth Structur 3 surface is particularly pleasant to the touch for the patient, who can now smile and eat without any worries with this temporary bridge.
Thanks to nano-hybrid technology, Structur 3 from VOCO puts in a “shining” performance in the criteria of handling, aesthetics and durability of self-curing composites. The dentist is able to produce high-quality and aesthetic restorations which feel good in the patient’s mouth and are also extremely durable – as well as taking less time. Reason for both patient and dentist to smile.
1. Fleming et al., Trinity College Dublin, 2012
2. Dr.-Ing. Lothar Borchers, Hanover Medical School (MHH), report on the commissioned study „Temperaturerhöhung in der Pulpa präparierter Zähne bei der Aushärtung von Provisorien aus verschiedenen Kunststoffen“ (Temperature rises in the pulp of prepared teeth when curing temporary restorations made from various composites), 26.07.11
3. Dr. Reinhard Lang, University of Regensburg