Maxillary First Bicuspid

The maxillary 1st bicuspids have a number of variations in root and canal configurations. Approximately 60 per cent have 2 roots, one buccal and one palatal, each with a single canal. The 2 roots may be completely separate or merely twin projections rising from the middle third of the root to the apex, with the latter slightly more common. Approximately 38 per cent of maxillary 1st bicuspids have only one root, usually with 2 separate canals (Type III). Type II canal configuration is present less frequently. Type I is very rare. A pre-operative angled view is very helpful in determining the type of root and canal configuration present. A rare combination of roots that occur in less than 2 per cent of maxillary first bicuspids and even less frequently in second bicuspids is the tri-rooted tooth, each root with one canal. Two buccal roots and one palatal root are present in these cases.

A cross-section at the cervical line shows a ribbon-shaped canal or one shaped like a figure of eight, with the widest dimension bucco-lingually.

Therefore, the access cavity preparation is thin oval, with the greatest width in the bucco-lingual direction. This is exactly the opposite of the occlusal cavity preparation in bicuspids.

For all bicuspids, the initial access preparation is begun by using a tapered fissure bur in the middle of the central groove. Initial preparation is made parallel to the long axis of the tooth. Buccal and lingual movement of the bur develops the oval shape needed for most bicuspids. Once the roof of the pulp chamber is penetrated, a safe tipped fissure bur is used to uncover the orifices to give direct access to the apices. The buccal canal lies beneath the buccal cusp, whereas the palatal canal lies beneath the palatal cusp.

In case of teeth with sclerotic canals, it is usually best to locate the canal that is farthest from the deep portion of decay or existing restoration and thus is least calcified. Careful examination of the floor of the chamber, aided by fiber-optic illumination, will show the ribbon shaped outline of the pre-sclerotic pulp canal. Further exploration at the end opposite the already discovered canal will soon reveal the missing canal.