Hello!Thank you for posting here.

Firstly, its very common to have molar roots into the maxillary sinus.
This perforation will heal by itself.Do not panic.It does not need a lifting.Its sealed once your doctor has sutured the surgical site.
Give it some time to heal.Do not smoke till it heals completely.Do not suck on anything.Do not use straw for having a drink.Take cetrizine to control your cold symptoms as you mentioned you sneeze.
See your doctor if it bleeds .Ideally bleeding should stop by now.Basic idea in doing apicectomy is to save the tooth.

Regards.

Hello,
Instructions following apicoectomy include not blowing your nose for three days, limiting vigorous activity and antibiotic therapy. Sneezing may result in symptoms described as you are still close to the surgery date. Continue to follow all instructions and avoid all situations that create pressure. You are still in the early stages of healing. A perforation will take time to heal and often a small oral-sinus communication will heal by itself. Informing your dentist of these current conditions would be best and determine when to schedule a followup visit. You may need additional medication such as a corticosteroid to reduce inflammation or a decongestant. It is possible that you develop a sinus infection that needs additional treatment.
Signs of inflammation including increasing pain and swelling are of concern. Drainage and/or bleeding from the sinus continuing over a week indicates a concern and possible improper healing. Fever and sinus pressure are signs of infection. So far, your description, with a perforation, appears to be within normal boundaries. Do not worry, but keep in communication with your dentist. Consider a second evaluation with an endodontist or oral surgeon if you continue to have complications.
Thank you for your inquiry. I hope my suggestions are helpful and the healing progresses well without any complications.