Patient with Persistant Infection: Recommendation for Implant Placement?

Dr. C asks:
I am asking for input on an interesting case I have been following in my office. The patient is a 50 year old male with no significant health problems. When he presented to my office about 1 year ago he had a buccal space infection on the lower left. His chief compliant was that the evening before he felt some food pierce his gums which he then tried to dig out and the swelling subsequently began over night.

Location of trauma to the attached gingiva was in the edentulous area of #19 [mandibular left first molar; 36]. Patient was not missing any other teeth. Pressure in the area of the swelling caused extrusion of purulent exudates through the traumatized area of the soft tissue. Patient reported that #19 had been extracted approximately 1 year prior. He said that he had a similar infection at that time and they decided to extract that day.

After going home following the extraction he started having seizures went to the emergency room and was told at the hospital that it was due to a bacteremia. I placed the patient on antibiotics and at the follow-up there was no sign of infection. Patient was interested in having an implant placed to replace #19 but I advised watching the area to be sure there were no following complications.

Approximately 1 month later patient returned with another infection. At this point I referred him to an oral surgeon who wanted to debride the area but the patient declined treatment. Patient returned approximately 1 month ago in pain. Source of pain was determined to be #18 with vertical fracture through the furcation with a 12mm probing on midbuccal. The oral surgeon consulting on case is out of the country. I decided to extract #18 and to lay a flap and to debride the area. Visual inspection of the area revealed a defect which can be seen in the photographs. I debride the area and obliterated the sinus tract.

Patient healed well following surgery but sinus tract returned and at every follow-up there has been a small amount of purulent exudate. I have patient irrigating the site with chlorhexidien 0.12%. I am wondering if anyone has ever seen this before? Patient wants implants to replace #18,19. I plan to graft the area at the time of implant placement. Any recommendations?