Restoration of a single central incisor with an all-ceramic crown: a case report
Basil Mizrahi illustrates and discusses the use of a resin bonded, glass based all-ceramic crown to restore a single central incisor.
Optimum aesthetics can be obtained using an etchable, glass based ceramic crown (Empress) in combination with a resin cement. The specific stages in treatment are described, as are the stages for actual bonding of the crown. The importance of a good temporary crown is also emphasised and discussed.
The restoration of a single central incisor is a demanding procedure. The patient’s aesthetic expectations are normally very high and the final result is heavily dependant on the dental technician. It is usually necessary for the technician to spend time with the patient at various stages while fabricating the crown and it is not uncommon for the crown to be remade if the aesthetic objectives are not achieved at first. These factors may increase the treatment time and patient needs to be made aware of this from the outset. The dentist needs to understand the technical difficulty and skill required to match a single crown to natural adjacent teeth and the high costs involved. Besides creating the optimal hard and soft tissue environment for the crown, the dentist needs to facilitate the opportunity for the technician to meet with the patient on one or more occasions if necessary. The initial meeting between the patient and dental technician should be at one of the patient’s dental appointments. This allows for any meaningful discussion to take place between all three parties.
Another important factor for success in these cases is the temporary crown. A well made temporary crown will immediately satisfy the aesthetic, functional and biologic requirements of the patient and dentist. Once this has been accomplished, time becomes a friend rather than an enemy and can be utilised by both dentist and technician to ensure success in all aspects of the final restoration - good things take time.
In order to utilise the temporary crown to its full potential, the dentist needs to ensure that it is an improvement on the existing situation. Failure to do this will be detrimental to treatment and increase the patient’s anxiety, reduce their confidence in the dentist and limit the time available for treatment. The dentist therefore needs to be able to create a temporary crown with good form, function and colour and be skilled in the use of materials that allow for this.
Methylmethacrylate acrylic resin is the author’s material of choice for the fabrication of all temporary restorations. The advantages of acrylic resin over the more popular bis-acryl automix products include (Mizrahi 2007):
Increased versatility in modification of shape and colour. Acrylic resins consist of a powder and a liquid that can be combined in various different consistencies and applied in various ways.
More amenable to remargination which allows for the creation of well fitting margins that in turn create healthy gingival tissue.
Better polishability and resistance to long-term discolouration. Surface glazes should not be used as they create a rough surface and tend to stain after a short period of time.
Because of their lower modulus of elasticity they can be easier removed from the underlying tooth without damage.
Early on in treatment, a decision needs to be made as to what type of crown to fabricate and the temporary crown will aid in this decision making process. Factors such as effect of the underlying tooth colour and the space available for restorative material can be assessed via the temporary crown. When attempting to match natural adjacent teeth, all ceramic crowns offer better potential for colour match than traditional porcelain fused to metal crowns (Douglas and Przybylska 1999). Much work has been carried out by Burke et al who have shown good long-term success with ‘dentine bonded crowns’ (Burke et al 1995, 1998, 2007, Burke and Qualtrough 2006, Burke 1999, 2000). There are two families of all-ceramic crowns to choose from:
Low strength, etchable, glass based ceramics.
High strength, non-etchable alumina or zirconia based ceramics.
The following case outlines the technique involved in restoring a single central incisor with a resin bonded, etchable, glass based ceramic crown (Empress, Ivoclar Vivadent, Liechtenstein) in order to achieve a predictable aesthetic and functional result with a good long-term prognosis.