Why do these files act differently at room vs. Body temperature?
MaxWire® alloy was specifically designed for XP-endo® instruments.
Like all Ni-Ti files, XP-endo® instruments have two phases:
A martensitic phase (M-phase) in which the instrument is malleable and can be manipulated into any shape.
An austenitic phase (A-phase) in which the instrument is superelastic and will always return to its original shape upon deformation. In this phase, the file cuts dentine more efficiently.
XP-endo® instruments are factory designed to be in the martensitic phase at 20°C (room temperature) and to move to the austenite phase above body temperature.
How can a file have more than one taper?
The XP-endo® Shaper has an ISO diameter of 0.30 mm and the taper of the metal core is 1%. It comes out of its package at room temperature in the M-phase and can be deformed.
When the temperature increases above body temperature, the instrument moves into the A-phase and expands to its characteristic serpentine shape. When the instrument is spinning, its coils produce an 8% taper shape (outside of the canal).
What is described above occurs when the instrument is free, without resistance to its expansion. In the canal however, the instrument will be initially constrained by the dentin walls and then, by cutting the dentin it will slowly expand to attempt to get to its potential 8% capacity.
This means that the taper the instrument achieves will be time dependent. Generally, it will reach a 4% taper after 10 to 30 long strokes to working length within the canal. A lesser or larger taper can be achieved by varying the time that the XP-endo instrument is used.
How do I get my working length?
The working length is determined similarly as done with a traditional file. When the XP-endo® instrument is inserted into the root canal, it is compressed between the dentine walls, meaning that the file gets straighter and thus tends to be at its maximum length.
However, as the canal gets larger, the instrument expands and its reach slightly shortens.
Overall, determining the working length is very similar to when using a straight file!
What is the difference between XP-endo® Shaper and XP-endo® Finisher?
The XP-endo® Shaper is designed to cut a specific shape in the canal that involves removal of dentin. On the other hand the XP-endo® Finisher does not cut or shape dentin. It rather scrapes biofilm and attached debris from the canal wall without changing the shape of the canal at all.
The XP-endo® Shaper has a lower expansion capacity compared to the XP-endo® Finisher. The XP-endo® Shaper can increase its reach 3 to 7-fold maximum while the XP-endo® Finisher has the capacity to increase its reach 100 fold!
Thus, the XP-endo® Finisher can reach areas that the XP-endo® Shaper cannot reach particularly irregularities such as resorptive defects or natural indentations inside the canal.
Do we need a XP-endo® Finisher, if the XP-endo® Shaper does the job?
There will be cases where the 3 to 7 times expansion capacity of the XP-endo® Shaper will be adequate to clean a canal effectively.
However, we have no way of identifying these cases clinically since we do not see the bucco-lingual dimension on the radiograph.
By adding the XP-endo® Finisher to all cases, we can be absolutely sure that we have reached all areas irrespective of bucco-lingual dimension, presence of indentations, and/or possible resorptive defects.
Why do we need the XP-endo® Shaper?
Since the XP-endo® Finisher has a core size of 25/00 it requires a size of at least ISO 30 in order to eliminate the chance that the tip will lock. Any file system can be used to achieve the required size 30.
However, the advantages of using the XP-endo® Shaper in order to achieve this size are the following:
It replaces a complete sequence of instruments. After a 15/.02 glide path is achieved, the XP-endo® Shaper will go to working length in 3-5 up and down strokes (due to the patented Booster Tip™) thus achieving the required ISO 30 size.
The serpentine shape of the XP-endo Shaper®, its flexibility and resistance to cyclic fatigue due to a 1% metal core and its expansion into areas where resistance is low, makes this file adaptive to the natural anatomy of the canal. Thus, the natural shape of the canal is respected even though dentin is removed. Full core files machine an artificial shape into the canal weakening the root in some areas while being inefficient at cleaning.
The thin metal core and serpentine shape further contribute to cleaning by creating turbulence within the irrigant volume, thus enhancing the antibacterial effect and removal of dentinal debris.
What is the part of XP-endo® Shaper that cuts the dentine? Does the XP-endo® Finisher work in the same way?
Both XP-endo® Shaper and XP-endo® Finisher have triangular cross-sections.
The external part of the coil of the XP-endo® Shaper cuts, whereas the XP-endo® Finisher scrapes the dentine.
The cutting capacity of the XP-endo® Shaper is due to its bigger ISO size (0.30) and taper (0.01). Also the “serpentine” shape , with its numerous coils, increases its cutting efficiency.
The XP-endo® Shaper cuts the dentine, while respecting the original morphology of the canal an does not generate round shapes because of its serpentine shape that is not aggressive (see Booster Tip™).
On the contrary, the XP-endo®Finisher has practically no cutting capacity. This is due to its smaller ISO size (0.25) and taper (0.00). The «sickle» shape, with its unique big bulb, generates a slight scraping action. It contacts the canal walls and removes the debris, the biofilm and the smear-layer. It goes into soft tissues and in areas where there is no resistance.
When I take the file out of the canal, it looks like it has lost its ability to expand?
We need to remember that when the XP-endo® instrument is placed into the canal it is squeezed into a narrower space, and it needs time to overcome the resistance of the dentine and fully expand to its austenite shape.
When we remove the instrument from the canal, it is in the squeezed shape and returns to room temperature and so it will stay in that shape.
The only way to really know if it has completely lost its ability to expand is to place the instrument in 37°C or above (e.g. warm water).
If it fails to regain its serpentine shape, it should be discarded.
CI metal handle - Color codes
FKG rotary instruments are equipped with a CI metal handle, depth marks and a silicon endo stop.
The aim is to provide easy identification of the ISO diameter (wide ring) and taper (narrow ring). The information remains visible when the instrument is inserted in the head of the contra-angle.
CI metal handles - Depth marks
The depth marks are used to recognise the position of the working length (WL) in the tooth and are additional to the endo stop. The depth marks are applied on all instruments in the XP-endo and Race ranges.
- Depth marks applied on instruments of length 21 mm/25 mm/31 mm
Examples of instruments with depth marks:
CM metal handles
The colour ring on the handle indicates the ISO diameter and the SafetyMemoDiscs (SMD) specify the taper of the instruments.
Silicone endo stop
The endo stop is used to mark the working length, it is radiopaque:
The stroke identifies the original tip direction in the root canal (SSt instruments).
ISO Colours indicate the file length.
Race - Customer benefits
Unique performance provided by all instruments in the Race range, for enhanced safety of use:
- Unique rounded safety tip for a precise guidance and centring of instruments.
- Patented design of alternated cutting edges to avoid screwing-in effect and to reduce the risk of breakage.
- Sharp cutting edges for an optimal cutting efficiency.
- Exclusive electrochemical polishing to increase resistance to torsion and cyclic fatigue of NiTi.
- SafetyMemoDisc (SMD) reliable monitoring of metal fatigue and number of uses.
Race - Golden rules for optimal use of Race instruments
- Speed: 600-1000 rpm - torque: 0.5 to 1.5 Ncm, depending on instruments see details.
- Broad back and forth movements without using force.
- Light hand, let the instrument do the work.
- Work for 3-4 seconds, remove.
- Clean the blade and irrigate the canal.
Race - Which motors can instruments of the Race family be used with?
Unit motors, to reach the minimum recommended speed of 600 rpm:
- Air motors 20,000 rpm: use a contra angle 32:1 reducer
- Electric motors 40,000 rpm: use a contra angle 64:1, 70:1 reducer
Endodontic motors, corded or cordless like the Rooter:
- Set the speed to 600-1000 rpm and the torque to 0.5 to 1.5 Ncm
Race - How many times can a Race be used?
The following are the instructions for the SafetyMemoDisc:
- 1 petal corresponds to simple cases, that is, straight, slightly curved or wide canals.
- 2 petals correspond to moderately complex cases, that is, more curved or narrow canals.
- 4 petals correspond to complex cases, that is, canals with extreme curvature or S-shaped, very narrow or calcified canals.
Although Race instruments can be sterilized and reused several times, it is recommended to use them according to the “single patient” principle to avoid the risk of cross-contamination.
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