Having horrible is different than having unhealthy teeth.If you dont like your smile there are always ways to give you the smile you have ever wanted with orthodontics and prosthetic dentistry, n case your teeth have severe periodontal problems or severe caries then it would be viable to explore tha possibility of getting them extracted and replaced by a implant supported prosthesis that would give you good function and esthetics.Please don't take a step like that without consulting with a specialist, preferably a prosthodontist that can explore the different options you might have to get that smile you want.
Any implant treatment needs to be prosthetically driven, meaning the specialist that is responsible to deliver the final restoration should be the one to plan the case, he becomes the quarterback of this cases, if the prosthodontist will be doing the surgical portion he will be responsible for the totality of the treatment, most prosthodontists will bring in a team, wither oral surgeons or periodontists to do the surgical part.Look in to the expertise that this people have, you can ask for before and after pictures of cases similar to yours, this usually helps in make in a decision.
The all on 4 procedure is completely different form a regular denture, the denture has flanges (pink acrylic extensions that cover all the facial portion of your ridge and a full palate, the all on 4 does not have this, it is more like a fixed bridge.Usually on a all on 4 the type of prosthesis that goes on top of the implants is called a hybrid that has pink on it but does not cover the ridge like the denture so when the patient smiles you can usually see some "gums", how much that depends on the patients specific characteristics like low or high smile line, hyperactive lip, bone reabsorption, etc.All this is assessed on the patient prior to starting the treatment but it is extremely hard to asseverate if you will show gum or not with out a clinical examination in order to consider all this factors.
What you are experiencing is the lack of a good inter proximal contact, that is the area where teeth touch between each other, if the crown was built without the contact you will need to get that crown replaced, in order to do this it needs to get cut off and a new one made, the existing crown can not have porcelain added at this point.
It seems that you have a problem with the retention of the crown that most of the time is because either the preparation was not well down and is too tapered or there is mort sufficient tooth structure to hold the crown, on either case you could have the prep rebuilt and get a new crown or in the worst case scenario you would have to get a root canal so you can get a post and have enough structure to hold the new crown.
