The best way to avoid bite wounds is to try and avoid the situations which would lead to them, namely watch your piggies when being introduced, and introduce them in a neutral territory, large enough for them to escape if need be, yet small enough for you to control. Personally, I like to introduce mine in the bathroom, as the floor is large enough for them to get away from each other, and there are a couple of hiding spots, yet small enough that I can control the interaction.
Most people think that adult boars do not get along, others swear they get groups that cohabitate peacefully. I've noticed that pigs are really a lot like people, two dominant animals won't get along and will step on each other's toes constantly (figuratively speaking) and will fight, whether it be over dominance or territory, we will not know. I personally have gotten boars to co-habitate much more successfully than sows. Usually, there will be some posturing, even mounting initially, but things will almost assuredly settle down in about 4-6 hours. If the dispute continues beyond that, it's time to separate them. Also, separate them if fur begins to fly, or pigs do bite at all.
Every once in a while, I find a sow that will not get along with anybody, except a breeding boar. In this case, I know she's a dominant animal, and will not put her in with an animal that is dominant, or one that is overly submissive. I will attempt to put her with a mild mannered submissive sow, or youngsters, as she feels she has less to prove to the youngsters. Once you find a happy living situation, do not break it up, as they have their hierarchy worked out.
Some folks suggest using taps to the nose, water bottle squirts, or loud noises, I find none of the above work, and it's just best to separate them if they aren't getting along. It's not a matter of just learning to get along, it's a matter of the sows and boars have a distinct personality trait, either they are dominant, middle ground submissive, or overly submissive. Dominants don't get along with dominants or overly submissive, and middle ground submissives get along with both others. Overly submissive piggies get along well with both middle grounds and other submissive piggies.
When piggies are fighting, they will most likely bite each other on the rear ends, and on the back, and sometimes on the back of the neck. I've only once dealt with a bite wound on the face. You'll see massive amounts of teeth chattering, flying fur, and piggies being chased mercilessly around the cage, and know it's time to intervene. Run your fingers over your piggy, searching for little scabs, torn flesh, and missing hair. They usually do aim for each other's heads and neck, but most often, divert the blow to the rear when they swing their hindquarters around, or get bit on the rump when being chased.
Sometimes you just simply won't see these wounds, and careful sensitive fingertips often find them when you are holding your pig. You might feel a scab, and the pig will wince or squeak with discomfort when you notice it. At that point, grab a towel, put the piggy on the folded towel on your lap or on a table, and investigate. Most of the time, they are already closed and on their way to healing, but sometimes you'll see the area inflammed and the beginning of an abcess. If you find that they are becoming infected, take a paper towel and press it against the bite wound, pressing out the pus. You can then squirt in some saline solution (you can find this at your grocery store 'contact lens' aisle) and then pack it with a bit of triple antibiotic cream or ointment. Keep a close eye on it for 3 days or so, at which point it should be healing nicely.
Oral antibiotics are not necessary at this point. Only are they necessary if the piggy requires sutures or the wound infection becomes systemic, which is extremely rare.