This mouth has been well treated in the past but the restorations are now failing. In particular the lateral incisor has lost two fillings, the pulp has died and the tooth is discoloured. It now needs a crown
the result of a blow from a hockey stick.Two incisors have been lost and the upper right central incisor is fractured, exposing the pulp, the fracture line extending subgingivally on the palatal side. The lateral incisor is fractured involving enamel and dentine only.
All the general indications listed above may apply to anterior crowns. Before the days of acid-etch retained composite restorations and composite and porcelain veneers, anterior crowns were indicated much more frequently for the restoration of carious or fractured incisors. Today many of these teeth can be restored without crowns, which are often not needed until the pulp is involved.
The central incisor has a necrotic pulp and is grossly discoloured. This degree of discoloration could not be resolved by bleaching or veneering the tooth.
When a pulp becomes necrotic the tooth often discolours due to the haemoglobin breakdown products. Internal bleaching is the initial treatment of choice and will often produce a good initial result, although sometimes some of the discolouration returns. However, the discoloration may be such that it can only satisfactorily be obscured by a crown following initial bleaching to produce a lighter core for the crown.
Gross tooth wear arising from a combination of erosion and attrition. This has passed the point where the patient can accept the appearance, and crowns are necessary.
The ideal approach to problems of tooth wear is to prevent the condition getting worse by identifying the cause and eliminating it as early as possible. Crowns should be made only when the cause of the tooth wear cannot be identified or cannot be eliminated, and the damage is serious. Sometimes the rate of tooth wear slows down or stops with no obvious explanation and the teeth remain stable for some years. Crowns are not a good preventive measure except as a last resort.
Extreme tetracycline staining with banding.
A moderate degree of amelogenesis imperfecta
(defects in the formation of enamel) in a 16 year old. The posterior teeth are affected more than the anterior teeth but the upper incisors are slightly discoloured and are chipping away at the incisal edge.
Dentinogenesis imperfecta (a defect in the formation of dentine) in a teenage patient. The incisor teeth have been protected with acid-etch-retained composite from shortly after their eruption and the first molar teeth have been protected with stainless-steel crowns. It is now time to make permanent crowns for all the remaining teeth.
In many of the hypoplastic conditions the patient (or parents) will seek treatment at an early age, often as soon as the permanent teeth erupt, and treatment may be carried out in conjunction with orthodontic treatment. In some of these cases large numbers of teeth are affected, and so the decision whether to crown them, offer some alternative form of treatment, or simply leave the condition alone, is a fairly momentous one. Differences in the lip morphology, the depth of uniformity of the colour, and the patient’s age and general attitude will all influence the decision. Unfortunately tetracycline stain often does not respond well to bleaching, particularly when the staining is in bands. The success of veneers depends on the quality of the remaining enamel for bonding, but in suitable cases veneers are the ideal treatment. The option of multiple crowns is a considerable undertaking and should not be embarked upon lightly by either patient or dentist. In particular with young patients, the lifelong maintenance implications must be fully understood. It should be explained that crowns are very unlikely to last the whole of a natural lifetime and replacements will be costly if they are possible at all. If veneers are made first the teeth can still be crowned later but the opposite is not true.
However, if after proper consideration crowns are made, they can dramatically improve the patient’s appearance in a way that is difficult or impossible by any other form of treatment. The decision often has to be made while the patient is a teenager, when social development can be seriously affected by appearance including dental appearance. This is often an important factor in making decisions on whether, how and when to treat.