Periodontal marginal and periapical diseases cause a huge destruction of tissues surrounding the tooth with periodontal patients. Treatment consists on elimination of pathogens, which are presented in periodontal pockets and also in root canals. To increase efficiency of endo-perio treatment there is used diode laser wavelength 940nm. Laser disinfection is done in periodontal pockets and root canals.

The aim of the study is to evaluate the effectiveness of treatment of endo-perio lesions with use of medicaments and diode laser.

The study will present cases of endo-perio lesions around molars in investigated and control group. Teeth were subjected to endodontic and periodontological treatment. The roots and pockets have been disinfected with a diode laser only in investigated group. In the both groups between the visits into root canals there were applied alkaline paste. The treatment was completed after 6 months. Before the beginning and after the end of treatment there were made a two-dimensional image and CBCT. CBCT was subjected to manual segmentation. The resulting streolitographic models were allowed to check the change of bone volume.

This study will presented the cases of two groups of patients, in which the endo-perio lesions were reported. The study protocol was approved by the Institutional Ethics Commission of Pomeranian University (No: KB-0012/29/17). Each subject provided informed consent after explanation of the protocol, risk and benefits of study.The both groups counted the same amount of molar teeth - ten molars in investigated (n=10) and in control group (n=10). In the study there were 9 men and 11 women aged between 35 and 58 years.

The study was performed according to split-teeth design, computerized randomly allocated to the control or the investigated group. At first group (investigated group) there were implemented periodontal and endodontic treatment with additional using diode laser wavelength 940 nm. The same steps were made in control group, however without using diode laser in medical procedures.

The first step was to do the clinical measurements (PD,CAL, tooth mobility, vitality test, occlusal condition) and analysis of pantomographic picture, the patients were diagnosed with third grade periodontitis The depth of periodontal pockets (PD) were checked by using manual periodontal probe (UNC 15, Hu-Friedy) on six sites. The classified teeth, which were diagnosed perio-endo lesions, were showed any vitality during testing faradic and ethyl chloride. The teeth did not respond properly. Also the tested teeth were checked with using Periotest M (Medizintechnik Gulden) in both groups before and after the treatment.

Every enrolled patients were checked by using the T-scan Novus (Tekscan). T-scan system records patients bite force, dynamics, including occlusal force, location and timing.

The treatment in EPL should be carried out in two ways- periodontal and endodontic. One of these ways there is mechanical non-surgical treatment of periodontium and endodontic way is eliminated the bacteria, which inside in root canals.

Inclusion Criteria:

• advanced periodontitis stage III, with endo-periodontal lesion without root damage,
• presence of at least 20 teeth,
• at least one molar tooth in each quadrant with a minimum of four teeth.

Exclusion Criteria:

-systemic illnesses (unbalanced diabetes mellitus, immunosuppressive drug or HIV), -

• pregnancy or lactation,
• smoking or alcoholism.

Documentation of study participants in paper form will be kept at the Department of Periodontology. We provide information on aggregate results in tables and statistical analysis after contact by email.