Aim: Preservation of natural dentitions is the primary (aim) of any conservative treatment modality, so IR is one of the techniques used to save the natural tooth.

I treated thirty infected hopeless teeth for thirty patients.

These cases cannot be treated with conventional endodontic therapy (or) surgery and the results were satisfactory.

In these papers I reported four cases had been done according to the same principle (IR) but differ in simple things such as: (the patient complaint, type of crown filling, type of fixation of the tooth, and time of follow up).

First case: A 23-years old male was referred to with a complaint of recurrent pain and discomfort in the mandibular right area. Clinically there was a sinus tract present, associated with the 1^st right molar, the crown repair with a large amalgam filling, radiology showed there was per apical radiolucency and root canal filling with unsatisfactory obturation. When the patient selects IR and refused other options, so IR was planned. Clinical and radiograph follow-up 6 months postoperatively revealed no sign or symptoms of infection or inflammation and the tooth retain natural function.

Second case: A 25-years old male, with a complaint of severe pain following the 2^nd visit of retreated Root Canal Therapy to the right upper second premolar. The patient refused to continue endodontic treatment and wanted a solution to keep his tooth the other way, after a discussion about the options that help him to keep his tooth, he selects the I R option. So, IR was done followed by clinical examination 7 months postoperatively revealed no signs or symptoms of infection or inflammation.

Third case: A 39-years old female, referred with a persistent dull pain at right upper teeth, clinical and radiological exam shown that there was apical lesion. I R planned after agreement of patient, post-operative follow up revealed no sign or symptom of infection or inflammation.

Fourth case: A 20-years old female, referred a complaint of severe pain in the right mandibular molar, clinically there was a large carious lesion, the gum swollen, radiograph showed that there was an apical lesion around the apical root of 3^rd molar. IR was done, after follow up the tooth was healthy and functions.