Even one dental implant means that, after healing, the patient needs periodic periodontal (vs general) cleanings since there is no gingival attachment?

Yes. After dental implant procedure you still need to have regular and periodic dental hygiene maintenance ti ensure it's long term success.
Not correct! Having an implant means you still have to see your dentist on a routine basis for cleanings, but what is different is that you need to know is that your dentist will use special instruments to clean around your implant(s). Most everything else will remain the same along with your special efforts with hygiene.
Depends. Generally you should see the doctor who placed your implant annually to make sure that you do not develop peri-implantitis, and if you do, that you catch it early. There is some gingival adhesion to the implant collar but, if i understand your question correctly, you are correct, there is no traditional connective tissue attachment to the implant like to a tooth - its lower quality.
Deep versus lite. Implants need dental cleaning as does the natural teeth. If you have periodontal disease, you need a perio cleaning 4X a year, If you have healthy gums than a regular cleaning will be fine 2X a year.
General or Perio. To get to the heart of your cleaning question, your dental gum history has more to do with your cleaning as compared to the fact you have an implant. If you have a history of periodontal pocketing and problems this would most drive the type of cleaning you will receive. We do want the gum tissue to bind tightly around the implant to form a gasket that would keep bacteria out. Best to you!
Correct. If there is loss of gingiva around the dental implant maintaining the dental implant is very important. Often your dentist will be able to maintain healthy gums around the dental implant as long as you brush and floss properly and frequently on your own.
Of course. The key word here is periodic. This is not to say that you need to come in every month. However, every 4 months is adequate. Due to the lack of gum tissue around the implant, recession is more common, which could cause bone loss and implant thread exposure. Another option is to have the area grafted with tissue to correct the small deficiency.
I do not agree... There is an establishment of a gingival attachment. There are measurable pocket depths. If all is within normal limits then we do still see patients the regular interval of six months. We have been following some patients for over 20 years in this way without a problem.
No. Regular cleanings by a hygienist familiar with implant cleaning is just fine. You should be maintaining it with normal cleaning techniques, supplemented with waterpik use and an electric toothbrush, and flossing in a shoeshine technique. Very basic and uncomplicated once you are educated in how to do it.
Same. Bacteria colonized the tooth surface and may cause periodontitis, which is a disease that leads to loss of supporting bone and ultimately toothloss. Similarly, bacteria colonized the implant surface and may cause periimplantitis, which is a disease that leads to loss of supporting bone around the implant and ultimately loss of implant. Implant cleaning required the use of nonmetallic instrument.
Periimplantitis? Progressive bone loss around a tooth is a sign of periodontitis. Progressive bone loss aound an implant indicates periimplanatitis. They both required periodontal cleaning. Gingival attachment with junctional epithelium occurs around a tooth, where as a strong epithelial cuff established around a healthy implant. If this is determine, a regular cleaning is adequate. Check with your dentist.
Absolutely. Dental implants are retained by bone and surrounded by gum tissue. Routine cleanings and evaluations need to be performed.