After testing out many of the various options online, the best economical slow speed combo online is this "slow low" dental handpiece Denshine kit for as low as $36, shipped.
Buy the "slow low" handpiece kit here on eBay (affiliate link)
Why this kit over all the others?
This kit combines all the pieces I like using into one combo: a slow speed motor, a push button contra angle, and a straight nose cone.
Updated Denshine Slow Speed Motor : The direction ring has slightly less play than the version before it. That means it's less likely to get stuck between fully forward and reverse. Like the previous version, it has plenty of torque--if you floor it. My two criticisms of it follow, too: the irrigation port that sticks awkwardly out to the side to squirt your patients, and the lack of low RPM torque. It simply stalls until you have half throttle. This makes low and slow prophies difficult for me.
All that said, it gets the job done, so pretty much all of my restorative kits use this slow speed motor. Since it's basically $10-15 to replace it, I simply throw it away once it breaks down. Of ten or more motors I've purchased, one or two were discarded. Even if they were half as reliable, I could buy 50 of these for the cost of a German slow speed motor.
As for the irrigation port, plug it with some blue bleaching tray resin, and cure it. Turn down the water output on the slow speed hose as well. And remember to turn off the water at the rheostat (foot pedal) as well. It will run fine with water through it, but there's no need to do so.
Search for slow speed motors a la carte on eBay here. (affiliate link)
Push button contra-angle - the affordable latch angles on eBay are easier to engage the bur, but the latches themselves are secured with a non-captive screw. Which means if that little eyeglass sized screw comes off, the latch falls off--and maybe your bur with it. So I prefer the push button contra-angles. This button reliably releases the bur, but it sometimes struggles to fully engage it after a few months. I've had some burs that seemed engaged, but then started to slowly spin out of the handpiece while in the mouth. Practical safety tip - always give your slow speed burs a good tug before spinning them in the mouth. The collar joint in the middle can also come loose, so you'll have to occasionally tighten them, too. (I had to do the same on my Midwests, too, just not as often) Remember, these are $12-15 contra angles; if you have realistic expectations, they are an amazing value.
Search for push button contra angles a la carte on eBay here. (affiliate link)
Updated Denshine nose cone - this is probably my favorite piece of the combo. I just have one in the office, but it's a gem. The bur release is firm, but sure. It engages and releases reliably. It spins smoothly at all rpms. It grabs our Crosstex Twist prophy angles snugly.
Search for straight nose cones a la carte on eBay here. (affiliate link) Be careful--get this specific nose cone picture above; the other ones aren't nearly as good. With the other models, we have much more difficulty inserting burs, locking them, and especially getting them out. We were able to find it as low as $12 for a single nose cone, shipped.
Can I use these with my electric handpiece motor?
They are all e-type, so they should run with your electric micro motors as well. We use the nose cone with an older endo motor as our lab handpiece.
The Next Step Up : Inner water
The Skysea inner water slow speed handpiece is the next step up from the pure air driven handpiece. You'll notice the coupler connection has three o-rings instead of one, so that water spray can be passed to the contra angle. I've only had one for a very short time, but it's very promising. The low rpm performance is better--it's a bit harder to stall it out by going too slow. Don't get your hopes up--it's nowhere near as stall proof as an electric motor handpiece. But the best part is that they eliminated that annoying little irrigation spout on the side of the handpiece.
Search for inner water slow speeds on eBay here. (affiliate link) I found singles for about $56 from US sellers shipped at time of writing.
The inner water contra angle is built noticeably better, though bigger, than the non irrigating version. It's e-type, so like all the attachments here, should work with most electric handpiece motors. I have to say, it's kind of cool removing caries and polishing crowns with water spray on board.
Search for inner water contra angles on eBay here. (affiliate link) I found singles for as low as $23 shipped at the time of this writing. Be sure to filter for US sellers and sort by price.
Removing caries with water spray is actually kind of nice...after years of sloshing sludge around, the water spray clears the muck out just like it does with a high speed.
There is also an inner water nose cone available. Since it doesn't have a notch to mount prophy angles, I have not purchased one to evaluate. I don't see myself needing water spray for straight burs--certainly not at the expense of being able to to prophy polishing. For this reason, I also can't recommend all the three piece inner water slow speed combos I've seen posted. Who wants to water spray their denture adjustments?
Which one should I buy?Until I have more time to evaluate the inner water handpieces, I am going to continue recommending the "slow low" handpiece kit (affiliate link). It's a killer value for $36--I've paid more to repair ONE of the pieces, let alone buy the whole combo.
We use these motors mainly for restorative. For prophies, I suggest reading my post on affordable prophy polishing. My pick at $230 is considerably more than $36, but it's a much smoother handpiece at those lower prophy polishing RPM's. If you don't need to use reverse motion, I would use it for restorative, also. It's that good.
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Some final eBay buying tips:
Buy from US sellers. Returning to China is basically impossible.
Pick the free shipping item with the lowest cost. Shipping cannot be refunded, so by picking the more expensive "free shipping" listings, you'll be more protected from lemons.
Buy in bulk when it makes sense - the combo I listed at the very beginning of the article seemed less expensive than buying the individual items. But a 5 or 10 pack may be cheaper still.