A NOTE ON- Indications For Anterior Crowns

Caries and trauma                                                              

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.

Non-vital teeth

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.

Tooth wear

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.

Hypoplastic conditions

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.