On an envelope, in the most formal context, and therefore rarely used nowadays, a girl is addressed as Miss + First Name, and a boy as Master + First Name and then c/o of the parent. In a letter, "Dear + First Name," is correct. In direct address, again only in the most formal context, Miss and Master can be used.
A simple "Hi [child's name]" or "Hello [child's name]" is appropriate for greeting a child in a casual setting. If you have a closer relationship with the child, you can use nicknames or playful greetings like "Hey there, kiddo!" Just be sure to use a friendly and warm tone.
What is the proper salutation for a register of wills, e.g. Honorable John White?
the correct salutation for two men is Messrs
Hello.
Your Honor
Dean actually is the proper salutation. One could say: Dean Redmond, would you please sign this form? Alternatively you could just use the Dr. salutation or the Professor salutation if those are appropriate, which they generally are.
The proper salutation for a doctor is doctor or professor depending on their title. In writing the short form can be used which will be Dr. or Prof.
A proper salutation for greeting the president of a business is "Dear Mr. President". To conclude a letter, the proper word is "Sincerely" and a the name of the writer.
Miz.
miss
His/Her Excellency
A dentist can either have a Doctorate of Dental Medicine (DMD) or Doctorate of Dental Surgery (DDS). The proper salutation for a dentist is Doctor.
His honor or Your honor is the proper salutation for a retired judge. The use of the word judge in title and introductions is not used after retirement.