What type of dental implant crown is the strongest on molars. Lab made all porcelain, the cerec crowns, PFM or PFHNM crowns.  Which ones are worst.

Gold crowns. For strength and longevity, gold would be your best choice, for esthetic reason we use porcelain, zirconia is the strongest but it is very abrasive and can damage the opposing teeth, e_max blocks (cerec), or pfm should do well, in this case e_max, can be stronger then the regular pfm, but again it can be a bit more abrasive. The choice is yours.
Bruxier or All-Cast. While there are so many options for implant restorative crowns, probably the strongest in the molar region would be the new "bruxier" one piece crown or a full cast implant crown. Probably screw retained would be ideal, but as long as the abutment cement is completely cleaned out these two types of crowns would be least likely to fracture.
Zirconia. While an all metal crown may not break it can be worn through over time. A zirconia crown will last longer and be more cosmetic than a metal crown.
Consider this. Years ago, we would place all metal (gold), but no one wants that anymore. Strongest is bruxzir (all zirconia) -- for molar this would be "aesthetic" enough. These are actually metal, but look like all porcelain, although they do not have the life-like translucency that porcelain has. But for a molar they work quite well and do not abrade the opposing tooth to the same extent as porcelain can.
Strongest =all metal. All metal crowns are without a doubt the "strongest" restorations. Feldspathic ceramic (original cerec porcelain) and original "cosmetic " all ceramic crowns are the weakest. However a "strong" artificial crown may, abrade or otherwise unforgivingly traumatize an opposing natural or artificial tooth. The choice of a "strong" crown does not equated to the most appropriate crown.
Zirconia. We like to use zirconia crowns, but there is no best one. Metal ceramic crowns or all metal crowns need to be used somethimes, so have your dentist choose for you.
Alloy. The strongest crown would be a gold crown. The next would be an all zirconia crown. The weakest an all porcelain crown with no substrate.
Ask dds. Your dentist can examine your mouth and the opposing teeth to determine which kind of crown is best for you.
Dental implant crown. They come in many sizes and shapes and some are appropriate in some areas and not in others. Todays ceramics that are milled such as zirconia and lava type crowns are generally as strong as metal crowns provided there is sufficient thickness of material. Pfm crowns may be the one at risk for fracture as an implant has not movement like a natural tooth and you need room for metal and porcelain.