Dental crowns are a common and effective treatment option for individuals looking to restore the dentition. A 2021 survey revealed that 34 per cent of people had at least one crowned tooth, with prevalence increasing with age.
Crowns can bring aesthetic and functional advantages where an existing tooth is severely caries-affected, but some of the structure is healthy enough to remain within the oral cavity. Though these indirect restorations are inherently invasive – some anatomy must be removed prior to placement – they are far more advantageous than surgical approaches including extraction and denture or implant placement.
Ensuring patients receive high-quality restorations is essential. There are a number of potential complications that may arise from controllable variables, such as material choice and adhesive approach, which can be optimised through informed clinical judgement.
Made of stronger stuff
Conventional crown placement has yielded excellent long-term clinical results, and as dentistry has evolved, clinicians have been pulled away from the traditional metal caps.
As with nearly every other aspect of dental care, aesthetics has played a significant role in this. Orthodontics has seen the rise of clear aligners, teeth whitening has become a popular cosmetic procedure, and so it is of little surprise that the demand for metal-free materials with increased translucency for a natural finish has escalated. However, dental professionals must find a balance. Function and oral health must also be considered. As seen in the General Dental Council’s (GDC) Standards for the Dental Team, patient expectations may need to be tempered to meet their oral health needs, and in the scenarios where a desired outcome is not in their best interests – perhaps if it is driven by aesthetics – a clinician must diligently talk through all aspects of such care.
For example, zirconia crowns are renowned for their strength and durability, but the ability to match the surrounding dentition is thought to be bested – even if only slightly – by porcelain solutions. Some clinicians may combine the two, veneering porcelain onto a zirconia structure, but chipping of the material is a commonly reported complication. This is especially present in posterior restorations. All-ceramic crowns have been suggested to avoid chipping, but these instead can result in complete fracture. Bruxism, as to be expected, increases the prevalence of porcelain chipping three-fold. A zirconia solution may therefore be preferred where improved longevity is the first priority.
However, there is also the need to consider that a zirconia crown will be likely more expensive than a porcelain or even all-metal crown. Understanding that patients can be strongly influenced by the cost of each treatment, as well as the perceived functional and aesthetic benefits, is important when carefully supporting patient decisions.
Stick or twist
The choice of adhesive material and method in which it is applied can also impact the complications associated with crown placement, including retention.
Both resin-based cements that are used in conjunction with a tooth primer and self-adhesive solutions form a hybrid layer with dentine, creating the term ‘bonding’. Laboratory studies have shown that resin cements increase the retention strength of a crown greater than glass ionomer or zinc phosphate cements, two other popular solutions.
Adhesion onto dentine is a clinical challenge due to the presence of moisture and its organic and inorganic composition, but self-adhesive resin cements have been shown to be suitable due to their acidic monomers. Glass ionomer cements can also provide a strong chemical bond to dentine, but studies have noted they can be weaker when bonding to an artificial core or coping materials.
As zirconia crowns feature a low inherent surface roughness, they must be prepared to provide ample bond strength and increase crown retention. The preparation of the indirect restoration site is in many ways as essential as the chosen adhesive material.
Self-adhesive resins are preferred by many where appropriate, as they simplify the bonding procedure. The characteristics of a cement will affect clinical performance, and so dental professionals should explore the options available to them.
Materials you trust
Finding materials and adhesive solutions that you trust to deliver consistent, high-quality results is key. The RelyX Universal Resin Cement from Solventum, formerly 3M Health Care, is one solution. The cement offers superior self-adhesive bond strength to dentine, without the need for additional adhesive or primer in both light- and self-cure workflows. Indirect restorations can be placed with confidence, delivering long-term retention and success.
Dental crowns are a mainstay in restorative dentistry, and can be optimised through material and adhesive choice. Clinicians may need to adjust their preferences dependent on clinical demands – but materials you have confidence in are paramount.
For more information visit https://www.solventum.com/en-gb/home/oral-care/