Guidance Kit Procedure

 

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Determine the Insertion Details Using a Dental Model and Radiographs

The optimum three-dimensional position for each Infinitas mini implant is determined using both plain radiographs (e.g. a panoramic tomograph or intra-oral views) and a plaster model of the dental arch. Ideally, the mini implant should be located where there is a maximum depth of cortical and cancellous bone, whilst avoiding structures such as adjacent dental roots, the gingival papilla, neurovascular tissues and nasal/maxillary cavities. As such, a balance is struck between three parameters:

1) the topographical entry point of the implant

2) the angulation: antero-posterior (AP) angle of entry

3) the inclination: vertical angle of entry.

For example, where a patient requires retraction of the anterior teeth into a first premolar space then the mini implant is commonly located buccally between the second premolar and first molar teeth in this quadrant. The insertion point and angles will be influenced by the position and morphology of the adjacent dental roots. The vertical level and angulation of the entry point affect the implant head's proximity to the gingivae and emergence angle. These, in turn, influence the prominence of the implant head and the ease of application of traction components.

If a dental technician is to insert the mini implant analogue then the planned location and angulations should be prescribed in writing by the orthodontist, and ideally an ink mark placed on the dental model to indicate the exact insertion site.

Drill a Pilot Hole in the Model

A pilot hole is drilled in the patient's dental model, using an analogue drill (DB10-0035 or DB10-0036) in either a straight or contra-angle dental hand piece, or in a laboratory hand piece (DB10-0037), to a depth of approximately 10 mm. It is critical that the drill is held at the correct 3D angulations to ensure that the desired vertical and mesio-distal insertion angles are produced. This procedure is normally performed 'free hand', but if desired, a technician may use the analogue drill in a vertical pillar drill with the model set on an adjustable angled table (as described in Cousley RRJ, Parberry DJ. Surgical stents for accurate miniscrew insertion. Journal of Clinical Orthodontics 2006; 40: 412-417).

Place Mini Implant Analogue in Model

The mini implant analogue (DB10-0030) is inserted manually and fully seated using the Analogue Screwdriver (DB10-0038) rotated in a clockwise direction. The location and angulations of the analogue should then be checked. If the 3D position of the analogue is dissimilar to the planned details then the analogue should be removed and the drilling and insertion process repeated.

Fit Abutment onto Analogue

The Infinitas Stent Abutment (DB10-0031) is manually fitted onto the head of the analogue.

Fit Guide Cylinder onto Analogue

The Infinitas Stent Guide Cylinder (DB10-0032) is fitted by sliding it over the Infinitas abutment until it contacts the plaster model surface.

 

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Fabricate the Stent Baseplate

Plaster separator (cold mould seal) is applied to the plaster model. A 1.5 mm thermoforming baseplate, such as the Infinitas Baseplate which is available in Round or Square versions (DB10-0040R or DB10-0040S) is placed on top of the assembled model, abutment and guide cylinder components. It is then pressure-formed onto the model using a machine conventionally used for retainer fabrication.

When placing the model into the pressure forming machine the guide cylinder should be in a vertical position (standing upright), this helps to create a fold in the base plate material from the guidance cylinder to the palatal or buccal surface of the stent, (to help with removal of the stent from the plaster model it may be necessary to block out all undercuts).

The baseplate now incorporates the guide cylinder and they are removed en masse from the model and abutment. The baseplate's labial and lingual edges are trimmed, and the superficial end of the guide cylinder is opened by cutting through the covering baseplate layer.

The mini implant insertion site is exposed by relieving 3-4 mm of the fitting surface of the guide cylinder and adjacent baseplate. This provides open visual access of the insertion site without detracting from the positive guidance that the cylinder provides for the screwdriver. It also makes it easier to remove the stent from over the mini-implant head when the latter is not yet fully seated (during clinical insertion).