Preservation of the primary tooth is the best method of space maintenance for its successor. However, teeth with infected root canals are a common clinical problem. Pediatric dentists routinely counter primary teeth showing signs of irreversible pulpitis and pulpal necrosis. The treatment in such cases are conventional approach or teeth extraction. Conventional root canal was introduced in early 1932 to save primary teeth that otherwise would have been extracted. Conventional endodontic therapy is aimed at elimination of microorganisms from the infected root canals and prevention of reinfection. Premixed calcium hydroxide and iodoform paste is a universally accepted obturating material for pulpectomy in primary teeth. However, root resorption of primary molars has been found to be accelerated following pulpectomy with conventional iodoform containing filling materials, leading to their early shedding in comparison with homologous teeth without endodontic treatment. 

The further challenge presented to the pediatric dentist in such conditions where extraction has to be advised and pulpectomy can’t be done in cases of pathological like internal or external root resorption. Premature loss of primary teeth bring about disturbances like ectopic eruption, altered eruption sequence, crowding, delayed eruption, space loss, functional and speech impairment. So, these types can be managed with  86.4% of success rate with LSTR.

Hoshino of Niigata University School of Dentistry invented the concept of LSTR therapy in 1990, and popularized by Takushige , in which a mixture of antibacterial medications was used to sterilise root canals. These new medication combinations were discovered to be capable of sterilising carious lesions as well as infected necrotic pulps of deciduous teeth. It has been also demonstrated that having LSTR in resorbed teeth, the periradicular radiolucent lesions like inflammatory root resorptions disappeared or reduced, thus the lesions repaired. 

Keeping in view all these things, this technique which is less invasive, less time consuming, and come with primary aim of elimination of all the microorganism i.e, sterilization of root canal spaces which results in good healing. This proves to the beneficial alternative to the conventional root canals which has limitations in various fields like extensive root resorption, inadequate bone, and periodontal support, a child belonging to pre-cooperative age group, and which is also less time consuming and can be done in one or two sittings. 

As it needs the application of a different antibiotic combinations known as "Triple Antibiotic Paste" (TAP) which was developed in major part by Hoshino and colleagues . Eventually, the antibiotic paste and its impact on microorganisms present in carious dentine and diseased pulp received special attention. The results indicated that the microorganisms had been completely removed from the radicular system. TAP is a triple antibiotic that contains ciprofloxacin, metronidazole, and minocycline. TAP can affect both gram-negative and gram-positive bacteria, and this combination can be effective against odontogenic microorganisms .

Numerous studies have found that minocycline causes tooth discoloration . So, in this vivo study we are using Double Antibiotic Paste(DAP) as it was found to cause minimum or no tooth discoloration in comparison to minocycline containing TAP

Thus, in this present case control study we will compare the success of LSTR technique in non vital primary teeth with and without incidence of pathological resorption using DAP with propylene glycol as vehicle.