Determining the positioning of the tooth concerned
This step plays a key role in our protocol. Determining the ideal
position of the tooth and its placement will allow us to preserve the
dental tissue to the maximum extent possible and guarantee optimal
durability of the restoration.
The goal is to provide sufficient space for a veneer or direct composite
resin restoration. In order to avoid parasitic movements on the other
teeth, the rehabilitation of the riziform tooth with the mock up
facilitates this positioning step.
Transversal direction
Sufficient space must be maintained for the restoration (0.5 mm for
veneers and 1.5 to 2 mm for the direct technique) (27). The mesial (M)
and distal (D) spaces must be evenly distributed to better mimic the
tooth tissue (same amount of Enamel/Dentin in M and D). To achieve this,
the tooth must be positioned in the middle of its space. In cases of
dental disharmony with persistent anterior space, we recommend either a
diastema distal to the lateral (studies show that this is the least
unsightly location in a smile) (3,31) or a diastema distal to the
canine. In general, diastema is considered unsightly by the general
population (26).
Vertical direction
Within the framework of a rehabilitation with a facet, a palatal
covering can be performed (32,33). Depending on the patient’s occlusion,
an anterior overlap of -2 to 0 mm may then be indicated in order to
avoid excessive preparation of the incisal edge of the riziform tooth.
In addition, the taller the tooth, the lower the width/height ratio will
be and the more esthetic the tooth will be (23,24,34). This notion is to
be taken into account if the space of the riziform tooth is too large
and therefore requires an increase in its M-D diameter. According to the
situation, to avoid any periodontal surgery, we recommend to take
advantage of the orthodontic treatment in order to harmoniously position
the gingival edges (35).
Antero-posterior
direction
Since an additional thickness will be added to the vestibular of the
riziform tooth, we recommend placing the tooth in question in the
palatal area and thus avoiding an alignment of the incisal edge with the
other teeth in order to limit dental preparations.
The fact of absolutely wanting to close the space between the teeth can
lead to a tooth that is too square (especially in the case of
dento-dental disharmony) (34). If the M-D space is too large, either the
diameter of the adjacent teeth can be increased or the incisivo-canine
block can be receded. If these solutions prove to be unattractive or
dysfunctional, a 1 mm canine advance (thus having a light canine class
II) to close more of the D-space of the riziform tooth, without
disturbing the anterior guidance can be done.