Ok on my JD 644C ,I found out pretty quickly I need teeth on the bucket. Has straight cutting edge now. I couldn't get it to dig dirt, still learning too. I have a 9ft wide ,4 1/2 yd bucket. what kind of teeth and adapters do I need? or how do I figure it out? Also, how many, spacing? Any help greatly appreciated!
Does your cutting edge have two roles of holes in it. Also that size rubber tired loader even with teeth will be slow digging in hard virgin dirt.
No holes ,so weld on or mag drill. that big bucket sure makes maintaining driveways nice!
Contact a wear parts dealer. Any of our machines with teeth have cutting edge segments between each tooth
Scroll down to 950g purchase. You can see a bucket with the tooth shanks removed
If you add teeth, it won’t back drag as well for the driveway.
Do you have a quick attach. A second bucket with teeth would be handy. 9 feet seems big for a 644
A quick search came up with the information that the standard/normal bucket size for a 644C is in the 2.75-3.5 cu.yd. heaped capacity range. That being the case a 4.5yd bucket sounds very much like a "light materials" type to me. Light materials buckets generally have a smooth cutting edge, sometimes with bolt-on wear plates but that's about it. They are not designed/intended for the installation of teeth. How about posting a photo of it.? The possibility exists that the cutting edge on your bucket is not strong enough to resist deformation under normal operating loads if you were to install teeth on it.
I would listen to what Nige is saying. I added bolt on teeth to my general purpose bucket on my Case 580SM backhoe and did more damage to the bucket than what it was worth....
When using my backhoe for removing material in my borrow pit, I always back in first and run my hoe through it to loosen it up and look for eggs. I can usually get 3 or 4 good buckets after that.
I hadn't considered the cutting edge not being strong enough, good catch. It's a pin on no quick attach. I really do the finish from the smooth edge. Let's see if I can do pics. 
Good so far but how about a photo of the cutting edge.?
Don't have that on my phone. I'll get it
It's kind of important when we are considering the feasibility of bolting or welding something to it.
It doesn't look like a really heavy duty bucket. Maybe you can Google the part number and get some info on it.
Didn't get a chance to get a pic of bucket, blew hoist hose, it's flat on the ground for now. But I do see what you're talking about, not a strong build on the cutting-edge assembly. Don't think teeth are a good idea at all.
Looking at the size (capacity) of the existing bucket I think you would be well advised to start casting around for a General Purpose bucket w/teeth somewhere around the 3 cu.yd size.
I was thinking along those same lines