Application of Photodynamic Therapy and Diode Laser for Endodontic Therapy of Young Permanent Teeth

Application Success of Photodynamic Therapy and Diode Laser During Endodontic Therapy of Young Permanent Teeth

The pulp necrosis of permanent immature teeth implies the interruption of the root formation and apical closure. Diode lasers have been used in many areas of dentistry, with tendency of good results in canal and dentine disinfection. The bactericidal effect of high-power lasers is based on dose dependent heat generation. Its antimicrobial effectiveness against diverse microorganisms has already been demonstrated. Photodynamic therapy (PDT) is a two-step therapeutic approach starting with the application of a photosensitizing agent and followed by irradiation with light energy that is spectrally matched to activate the drug. The balance between disinfection and the creation of an intracanal microenvironment conducive for the proliferation of stem cells requires further investigation. Aims of study are to compare the time required to obtain the clinical healing and the disappearance of clinical symptoms, and absence of periapical radiolucency, by using PDT and diode laser, with standard disinfection alone; to assess specificity of microbial load in permanent immature teeth, and root canal disinfection ability of PDT and diode laser, in compare with standard disinfection alone.

Background and Significance The pulp necrosis of permanent immature teeth implies the interruption of the root formation and apical closure. It is then necessary to implement a therapy to induce a calcified barrier at the apical end of the root. The endodontic management of permanent immature teeth is fraught with challenges. Although treatment modalities for vital pulp therapy in these teeth provide long-term favorable outcome, the outcomes from the treatment of pulp necrosis and apical periodontitis are significantly less predictable. Key role of microorganisms in the causing and development of pulpal and periapical diseases have been demonstrated, and their presence in the canal at the time of definitive filling has negative effect on success of the therapy. However, the specificity of microbial load of immature permanent teeth is not completely investigated, nor the influence of the disinfection protocols on treatment success. Available procedures rely heavily on root canal chemical disinfection of the root canal system, with minimal mechanical instrumentation. Sodium hypochlorite (NaOCl) in different concentrations is the most accepted solution for disinfection of root canal in endodontic. Despite common usage, impossibility of NaOCl to completely disinfect root canal has been noticed. Traditionally, irrigants and medicaments have been chosen for their maximum antimicrobial effect without consideration for their effects on stem cells and the dentinal microenvironment. The balance between disinfection and the creation of an intracanal microenvironment conducive for the proliferation of stem cells requires further investigation. This requires the interpretation of preclinical studies, and this level of evidence should be increased by randomized controlled clinical studies. Diode lasers have been used in many areas of dentistry, with tendency of good results in canal and dentine disinfection. The bactericidal effect of high-power lasers is based on dose dependent heat generation. Its antimicrobial effectiveness against diverse microorganisms has already been demonstrated. Photodynamic therapy (PDT) is a two-step therapeutic approach starting with the application of a photosensitizing agent and followed by irradiation with light energy that is spectrally matched to activate the drug. Because its high antibacterial potential, usage of photodynamic therapy as advance to standard protocol in root canal disinfection have been suggested. Studies showed positive effect of photodynamic therapy in the reduction of microbial load in root canal treatment. When a photoactive compound is applied in the root canal system, it is taken up by residual bacteria in the main canals, isthmuses, lateral canals and dentinal tubules. It is also possible that this compound may escape into the periapical tissues. During PDT, light will excite the drug in bacteria within the root canal, but could also potentially affect the apical stem cells that have taken up the drug. Therefore, it is important to determine the therapeutic window whereby host cells are left intact. Several studies showed wide-ranging spectra of desirable effects of low level power laser (LLLT) on biological tissue. It has been reported to increase cell functional activity, induce cell proliferation, lowers inflammation, releasing of endorphins, thus having analgetic effect. Furthermore, it has been shown that irradiation with a LLLT following photosensitization with phenothiazine chloride had no negative effect on the growth and differentiation of human osteoblastic cells, and did not counteract the biostimulatory effect induced by LLLT. There were no statistically significant differences in the growth and differentiation behavior between the two study groups. Further investigations of PDT on dental stem cells are needed to determine possible biostimulative effect on proliferation and differentiation, and thereby contribute to root development of non-vital permanent immature teeth. Prolonged treatment of young permanent teeth increases possibility of treatment failure. Involvement of a method that could help healing process is desirable.

Chemomechanical preparation will be completed by hand instruments, with minimal instrumentation, and usage of sodium hypochlorite with minimal bactericidal concentration (0.5%, pH 12), on room temperature (21 degree Celsius). After that, HELBO treatment (Helbo Photodynamic System, Bredent, Senden, Germany) will be applied.

Chemomechanical preparation will be completed by hand instruments, with minimal instrumentation, and usage of sodium hypochlorite with minimal bactericidal concentration (0.5%, pH 12), on room temperature (21 degree Celsius). After that high power diode laser therapy will be applied by using Epic diode laser (Biolase® Technology, Inc., San Clemente, CA, USA).

Chemomechanical preparation will be completed by hand instruments, with minimal instrumentation, and usage of sodium hypochlorite with minimal bactericidal concentration (0.5%, pH 12), on room temperature (21 degree Celsius).

Dentin sealant (HELBO® Endo Seal, Bredent, Senden, Germany) will be applied over the crown area and light cured. The root canals will be filled with the phenothiazine chloride (HELBO® Endo Blue, Bredent, Senden, Germany), agitated with a size 15K-file and left in the canal for 2 min. After this time, the root canals will be rinsed with distilled water to remove the excess of the photosensitizer, dried with paper points. The disposable 450 µm fiberoptic tip (3D HELBO® Endo Probe, Bredent, Senden, Germany) will be placed in the apical portion of the root canal at the point where resistance to the fiber will be felt, and root canal will be irradiated with HELBO® TheraLite Laser (λ = 660 nm, power = 100 mW) for 60 s (total energy, 6 J) in a continuous wave mode.

High-power diode laser therapy will be applied by using Epic diode laser (Biolase® Technology, Inc., San Clemente, CA, USA) with settings determined in laboratory researches (λ = 940 nm, maximal power 10W).

Chemomechanical preparation will be completed by hand instruments, with minimal instrumentation, and usage of sodium hypochlorite with minimal bactericidal concentration (0.5%, pH 12), on room temperature (21 degrees Celsius).

Number of teeth without viable bacteria load in root canal after Photodynamic therapy and Diode laser in endodontic therapy

Number of teeth without viable bacteria load after treatment in all experimental groups, will be determined. Microbiological samples from the root canals will be collected immediately after the accessing the canal, following endodontic treatment, and after the laser procedure in adequate groups (Photodynamic therapy or Diode laser). Samples from the root canals will be cultivated in conditions suitable for growth of anaerobes and facultative anaerobes.

Number of teeth with periapical healing 6 months after treatment, will be determined by PAI score index, in all experimental groups. Teeth will be categorized in five groups depending of PAI score: (1) normal periapical structure; (2) small changes in bone structure; (3) changes in bone structure with some mineral loss; (4) periodontitis with well-defined radiolucent area; and (5) severe periodontitis with exacerbating features.

Inclusion criteria a non-vital permanent immature single rooted tooth primary endodontic infection 6 - 18 years old written informed consent obtained from each parent and child Exclusion criteria uncontrolled diabetes mellitus, immunosuppression, severe asthma usage of antibiotics, anti-inflammatory, corticosteroid, or immunosuppressive therapy during the last 6 months need for antibiotics at current endodontic therapy need for antibiotics in prophylaxis of systematic disease before endodontic therapy periodontal diseases impossible adequate isolation of the tooth

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