In linguistic usage, the term deciduous crown is used on the one hand for the natural crowns of the 1st dentition (part of the deciduous teeth protruding from the gum), but on the other hand also for fabricated crowns, which are used on deciduous teeth in case of severe substance loss in their crown area, in order to preserve the affected tooth as far as possible until the physiological (natural) tooth change. Anterior teeth of the 1st dentition (deciduous anterior teeth) with a large loss of substance are usually restored with common filling materials, using shaping aids such as Frasaco copings or polycarbonate crowns, which are filled with the restorative material. Therefore, the following discussion deals with the fabricated steel crown/nickel-chromium crown for the restoration of 1st dentition molars (deciduous molars).
Indications (areas of application)
Since the fabricated crown encircles the rest of the tooth in a circular (annular) fashion and simultaneously compensates for the loss of hard substance due to carious damage after excavation (removal of caries), the following areas of application result preferably in deciduous molars (molars of the deciduous dentition), but also in infantile or juvenile six-year molars (first posterior molars of the permanent dentition):
- Large loss of hard substance after caries excavation (caries removal); usually several tooth surfaces are affected; even on permanent molars, the use of large deciduous crowns is possible here, since definitive crowns are only possible in adulthood; steel crowns are prognostically more favorable with regard to the survival of the deciduous tooth until natural exfoliation (tooth loss) than expansion-related complex fillings;
- After endodontic treatment (treatment of the pulp) such as pulpotomy (removal of the crown pulp) or pulpectomy (removal of crown and root pulp); both procedures involve a strong loss of hard substance starting from the occlusal surface area, since a wide-area access to the pulp (to the pulp) must be created;
- Hard substance loss due to fracture (fracture);
- Dysplasia (developmental disorders) of enamel or dentin even permanent molars; care also in this case to bridge the time until the definitive crown restoration in adulthood;
- Prophylactic (precautionary) crowning in children with mental and / or physical disabilities, who can thereby only operate very limited oral hygiene;
- To prevent elongation (lengthening) of the antagonist (contact tooth in the opposing jaw).
The procedure
Thus, the use of a fabricated deciduous crown aims to restore the masticatory function, through the fact that the restored tooth comes back into contact with its antagonist (contact tooth in the opposing jaw). Moreover, the natural distance between the neighboring teeth is maintained in its dimension, so that the six-year molar (first molar of the permanent dentition) cannot move forward, thus constricting the dental arch or completely restraining the eruption of the permanent tooth under the one to be restored. The procedure that follows the preliminary restoration in the form of endodontic treatment or caries removal is as follows:
- Measuring the distance of the adjacent teeth;
- If necessary, build-up filling for substance compensation;
- Preparation approximal (grinding in the interdental spaces): sparingly and running out e.g. with a separating diamond; the substance removal is sufficient if a probe can be moved through the interdental space;
- Occlusal preparation (grinding in the occlusal surface area): shortening by approx. 1.5 mm, whereby the occlusal surface relief should be preserved;
- Crown selection from assortment based on the initially measured value: crown must slip just above the tooth during the first fitting;
- Reduce length of crown with crown scissors if necessary; crown edge must extend well above the equator (widest part of the tooth), but may only slightly penetrate the gingival pocket;
- Work crown with special pliers on the edge so that a clear snap effect over the equator is achieved during insertion;
- Control of antagonist contact (contact with the tooth of the opposing jaw);
- Final placement of the crown, for example, with glass ionomer cement;
- Freeing the sulcus (the gum furrow) from cement residues;
- Renewed bite control.
Possible complications
- Crown chosen too small, can not be brought into position correctly as a result;
- Crown selected too large; as a result, no snap effect, premature crown loss;
- Crown correctly selected, but prepared approximally (in the interdental spaces) not tapered, so that the crown sits on a step; as a result, no snap effect;
- Early contacts with the antagonists (teeth of the opposing jaw); as a result, possibly inflammatory irritation of the crowned tooth or antagonist(s).
