* Dental Caps: A number of people are down in the mouth about dentists, judging from the response to free-lance writer David Hubler's story on selecting one. Poor mouthing from patients was expected, but not from the professionals themselves. Dentists, it seems, are putting some teeth into their public relations.

From Todd A. Davis, executive director, Virginia Board of Dentistry, came the reminder that unhappy patients have a further option: File a complaint, in writing and notarized, with your state board. If it's the coup de gra ce you're after--revocation or suspension of license--only the state board, which giveth the license, can take it away. Or, as Davis says, "put unsafe practitioners out of business."

A Columbia, Md., dentist and member of the Maryland Peer Review Committee sent off this precise, painstakingly handwritten list of further guidelines in choosing a dentist, things you aren't apt to know unless you're on the giving end of the drill. If you're dedicated about the matter--and want to dazzle a dentist--ask if he or she:

* Routinely uses a rubber dam for silver fillings.

* Uses sealants on children's first permanent molars.

* Belongs to the Academy of General Dentistry (AGD). ("To maintain membership in this group requires lots of continuing education courses.")

* Uses pre-proportioned capsules. ("If so, that's a good sign.")

* Uses a periodontal probe to check gums during the initial examination, or routine 6-month check-up. ("Ask to see it--if he has to get it out of the drawer, go elsewhere . . . I've been in offices that don't even own perio probes!")

And to probe even further into your prospective dentist's competence and conscience, the Columbia dentist suggests that you:

* Call a board-certified periodontist and ask for the recommendation of a general dentist.

* Call a dental lab and ask the manager for the names of three dentists who send impressions of single crowns of superior quality. "Virtually all laboratories know who the excellent dentists are, who are average and who are the poor ones.

"I could go on and on," groans the man. "It's frustrating to see some of the dental treatment that I see, not to mention what I see on new patients coming to my office." (Which is perhaps why he asked to remain anonymous.)

Salud! to "shoppers," he goes on. He just wants to see good merchandise put where a patient's mouth is.

* Lucy: Among the I-Love--Lucy fans who confessed to writer Carol Goldsmith that they feel vindicated in their Lucy lunacy was Janice Vranich of Fairfax: "Now I know how a born-again Christian must feel--there are other people in the world like me . . . The real reason I begged for (and got!) a video tape recorder for Christmas is so I can record 'Lucy' daily."

* Fifties Fillip: And now if we can get all those '50s fans to start wearing their sweaters backwards--as we did then--our wardrobes will be doubled. With retrospective chic.