Is there an option other than implants for a missing second molar?

The only option for a missing second molar without having an appliance that is removable is a dental implant.  This is your best option.  Good luck.  

I thing the best option for you is a bridge. It will replace your missing secong molar just if you have the third molar. They span the space where the teeth are missing. Bridges are cemented to the natural teeth or implants surrounding the empty space. These teeth, called abutments, serve as anchors for the bridge. A replacement tooth, called a pontic, is attached to the crowns that cover the abutments. As with crowns, you have a choice of materials for bridges. Your dentist can help you decide which to use, based on the location of the missing tooth (or teeth), its function, aesthetic considerations and cost. Porcelain or ceramic bridges can be matched to the color of your natural teeth.Gaps left by missing teeth eventually cause the remaining teeth to rotate or shift into the empty spaces, resulting in a bad bite. The imbalance caused by missing teeth can also lead to gum disease and temporomandibular joint disorders.Good luck!

If the upper molar is not present or the upper first molar is touching the lower molar to stop the eruption then you don't likely need to worry about replacement.Now as for the metal allergy, this is a concern.All metal implants are made of titanium alloys, these alloys have different metal ingredients in them.Some have aluminum and vanadium others have impurities such as iron and nickel.  Very few people are actually allergic to titanium but unfortunately the sensitivities to other metals are very common.If you know that you have a metal allergy then you may want to look into Ceramic Dental implants.  We have been placing ceramic implants for many years and they are completely metal free.  They offer an amazing solution that is both healthy, strong, looks like teeth and functional.  The success rates of ceramic implants is equivalent to that of titanium implants, if you need an implant then go seek out a dentist that can provide you with different material options. Good luck,

If you don't have an opposing upper second molar then you don't have to do anything. Also, if the second molar on top bites against the lower first molar, it probably won't move or over erupt so you should be fine as it is locked into place. You can also have allergy testing to asses if you have a titanium allergy. If not, then an implant will be your best bet to restore function long term. Good luck! 

While there IS another option to a dental implant for a missing second molar, most prefer the implant.  Quite often second molars are NOT replaced, even if dentures are being made.  The bite forces that far back and the limited space (from gumline of lower up to upper gumline or opposing tooth) can make it difficult for restorative materials to last any length of time. Often even placing an implant that far back is not advised, since the limited access may make it impossible to get the instruments at the correct angle to place the implant where it should be.The only true option is a removable partial denture.  To be sure that you DON'T swallow it, you would be required to have a metal framework that will be supported by the other teeth and spans to the other side of the mouth.  Most report that the bulk is so large for so little missing that they simply don't wear it.Another (better?) option is to simply polish the rough (or "not smooth") area that bothers your tongue.  You will eventually get used to it.