Should Dr. be spelled out in the inside address. Any other grammar/punctuation errors?

Dr. Robert E. Grant
Dental Care Associates
200 South Broad Street
Charleston, South Carolina 29401

Dear Doctor Grant

Retreatment has been completed on your patient, Janet Lee Jackson, on tooth No. 19. As you may know, we evaluated this tooth a year ago when Ms. Jackson was a patient of Dr. Youngblood. She has neglected to treat it until recently when the symptoms returned.

We discussed the options once more; I explained to Ms. Jackson that a fourth canal was definitely present, but the possibility of an apicoectomy also existed. I was also concerned a ledge would be present in the mesial canals and there was an increase in bone loss. She still wanted a retreatment, as opposed to an extraction, an implant or a bridge, so I suggested we file a pretreatment estimate and she could make her decision. Upon receipt of the estimate, she elected to attempt retreatment. The procedure was completed and a fourth canal was located. However, I was unable to get patency in the mesial canals so I recommended a six month recall to monitor the situation. She wants to wait until after the recall to have the permanent build-up placed in case an extraction is needed.

Thank you for referring Ms. Jackson to me. I appreciate your expression of confidence and will do all I can to continue to provide the finest in dental care.

Your inside address is fine -- with Dr. . . .

bridge, so I >> replace comma with a semicolon and delete so

The rest looks good.