Most if not all milling machines do not adequately cool the tools or restoration while milling. At CAD-Ray we have developed augmenting tools that reduce or eliminate any dry milling of glass ceramic restorations. We can either run tubing from the holding tank or we can submerge the block for soaked milling
The following pictures depict the sequence of burs we recommend that you use to finish a preparation quickly. While patient is getting numb, take a quick look at the clearance you will need to reach proper material thickness. Once the quadrant is isolated with isolite and optragate, take an occlusal router bur and create a trough to gain the proper depth. Follow that with a flat disk, and you can quickly reduce the occlusal height.
A shoulder bur of .8 mm thickness can help you reduce the interproximal areas as well as the buccal and lingual margin lines. Before finishing the prep, place hemostatic agent like expasyl in the sulcus and place retraction cord. while it is setting, check your reduction. If you need more space, now is the time to reduce some more.
Once you have adequate clearance, retraction, and hemostatis, you can readily image and find your margins in the CAD software
This molar’s suggested mill times with the MCXL are for either Size 12 or 14 blocks:
Sprue on distal in normal speed mode is 14:05 minutes, fast speed at 7:54
Sprue on buccal in normal speed is 13:48 minutes, fast speed at 7:46
This molar would only fit in a size 14 block of Amber Mill in Imes Icore Coritec
Sprue on distal in normal speed mode is 14:15 minutes, sprue on buccal in normal speed is 14:42 and speed crown is proosed at 13:23
For our advanced users who mill in house or what to speed up their digital impressions we advocate taking advantage of digital dentistry’s unique features that allow you to take impressions over a period of time and segments, building larger models over different sequences and time. In this particular case we have two molars in the lower left quadrant that warranted replacement. The traditional method would be to prep both, isolate both, retract both, and take your final impression, but we will approach this as if there are two separate patients involved
For the second molar, we will take advantage of the anesthesia time and capture the first bite, the opposing, the pre-existing situation and then crop out the preparation area digitally. Once the tooth is prepared, we will check for proper reduction. We will then take the second bite to verify the vertical dimension has not changed.
While the second molar is being designed and milled in the first case, we will launch a second window by cloning the first case. All the data remains the same and this time we crop out the first molar digitally and protect the rest of the arch. Once the first molar is isolated, it is digitally captured and then designed and milled.
To manage the contact between the two crowns, there are many advanced applications. Here is a simple explanation of how we use the prep model from case 1 as the pre-op model for case two. Since the second molar in case 1 made contact with the distal wall of the first molar, when we design the crown for the first molar in case 2, all we have to do is make sure the distal wall is flush to the pre-op. This guarantees us a contact between the two. There are lots of shortcuts to this puzzle once you get the basics of digital impressions under your belt.
We quickly printed these same models and crowns just for demonstration purposes
case 1 first molar
case 2 second molar
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