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Year : 2020  |  Volume : 11  |  Issue : 2  |  Page : 99-105

Lesion sterilization and tissue repair in primary teeth

Department of Pediatric and Preventive Dentistry, A. B. Shetty Memorial Institute of Dental Sciences, Nitte Deemed to be University, Mangalore, Karnataka, India

Date of Submission03-Dec-2019
Date of Acceptance19-Mar-2020
Date of Web Publication08-Jul-2020

Correspondence Address:
Dr. G Geethanjali
Department of Pediatric and Preventive Dentistry, A. B. Shetty Memorial Institute of Dental Sciences, Nitte Deemed to be University, Mangalore - 575 018, Karnataka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/srmjrds.srmjrds_87_19

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In primary teeth that are pulpally involved, pulp therapy is performed with the sole aim of maintaining the teeth until normal physiological exfoliation. This is to avoid any abnormalities in occlusion in the permanent dentition. However, conditions such as the presence of extensive root resorption and/or presence of furcal radiolucency may contradict pulpectomy, and in such cases, lesion sterilization and tissue repair seems to be a promising alternative to extraction followed by space maintenance.

Keywords: 3 mix MP paste, lesion sterilization and tissue repair, primary teeth, pulpectomy

How to cite this article:
Shetty AA, Geethanjali G, Hegde AM. Lesion sterilization and tissue repair in primary teeth. SRM J Res Dent Sci 2020;11:99-105

How to cite this URL:
Shetty AA, Geethanjali G, Hegde AM. Lesion sterilization and tissue repair in primary teeth. SRM J Res Dent Sci [serial online] 2020 [cited 2023 Mar 31];11:99-105. Available from:

  Introduction Top

Pulp therapy in the form of pulpotomy/pulpectomy is the preferred modality of treatment in case of carious lesions of primary teeth involving the pulp. However, certain factors such as extensive root resorption and/or presence of furcal radiolucency may contradict pulpectomy and extraction is the only treatment option in such cases. If an extraction is performed a space maintainer should be given to prevent any space loss that might occur. Lesion sterilization and tissue repair (LSTR) seems to be a promising alternative for primary teeth in which pulpectomy has been contra-indicated. A clear understanding as to how the concept came into existence and the rationale should be understood by the clinician before implementing the procedure. This review provides a brief overview regarding the evolution, modification and scope of LSTR technique in primary teeth.In vitro andin vivo clinical studies and case series in which LSTR was performed in primary teeth were included in this review.

  Evolution of Lesion Sterilization and Tissue Repair Top

The primary objective of pulpectomy is the removal of infection from radicular space which in turn leads to alleviation of signs and symptoms. This resolution of signs and symptoms is what that determines the success of pulpectomy as laid out by Coll and Sadrian in the year 1996 [Table 1].[1]
Table 1: Coll and Sadrian criteria for pulpectomy success (1996)

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The ways for elimination of bacteria from the radicular portion include:

  1. Adequate instrumentation (root canal debridement)
  2. Antibacterial irrigation
  3. Antibacterial filling material.[2]

All of this should facilitate the primary tooth that is free from infection to be retained for adequate amount of time in the oral cavity followed by normal exfoliation of deciduous teeth and permanent successor eruption.

Due to the morphology of the primary root canal being complex with excessive curvature and increased number of accessory canals, complete removal of infection is often difficult. So it is the antimicrobial activity of the obturating material used that takes care of the persistent microorganisms in the root canal space and prevents subsequent re-infection. But in addition to the antimicrobial efficacy it should also possess other qualities that renders easy placement, removal (if necessary) and normal physiological exfoliation of the primary tooth.[3],[4] The ideal requirements of an obturating material for primary teeth have been given by Rifkin (1982) and Machida (1983)[5],[6] [Figure 1].
Figure 1: Ideal requirements for obturating material for primary teeth

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None of the materials which are used currently in clinical practice satisfy all of this criteria. They lack in one or more qualities and it is due to this reason that there is an ongoing quest for an ideal obturating material. The whole reason as to why so much emphasis is placed on obturating material is the fact that they possess antimicrobial efficacy which would remove the infection from root canal space. If the infection is removed by some other means, the need for an obturating material will almost cease to exist. The localized administration of antibiotics in radicular space is one such method to eliminate infection.

The use of antibiotics in endodontic treatment is not an entirely new concept. Grossman in the year 1951 introduced the poly antibiotic paste which was composed of Penicilllin, Bacitracin, Streptomycin and Caprylate sodium.[7] Ledermix paste containing Triamcinolone and Demethylchlortetracycline is a well-known pulp capping agent which was used to control pulpal inflammation in primary teeth.[8] The first obturating material to have an antibiotic in its composition was developed by Sollier and Cappiello in the year 1959 who used a combination of zinc oxide eugenol, tetracycline and chloramphenicol which was called the Chloramphenicol- Tetracycline- Zinc oxide eugenol (CTZ) paste. Benfatti and Andrioni in the year 1969, used a mixture of zinc oxide and lancomycin as obturating material.[9] Later Guedes-Pinto paste was introduced in the year 1981. It had Rifocort® ointment which was a combination of prednisolone acetate (corticosteroid) and sodium rifamycin (Antibiotic). The other components being camphorated paramonochlorophenol (Liquid) and iodoform (powder). The main disadvantage regarding the use of guedes-pinto paste was manipulation that is the concentration of each part could be altered by different physicians thereby altering the biological properties which can impact the clinical performance or enhance the toxicity.[10]

A plethora of studies regarding use of antibiotics as a component of intra-canal medicaments and irrigants have been done in permanent teeth. It was as a result of various studies conducted by Sato, Hoshino & Takushige which proved the efficacy of the mixture of Ciprofloxacin, Metronidazole and Minocycline against endodontic micro-organisms, that a concept called “LESION STERILIZATION AND TISSUE REPAIR: came into existence [Table 2]. It was developed at the Cariology Research Unit of Niigata University School of Dentistry, Japan. It comprised of three drugs namely Ciprofloxacin, Minocycline and Metronidazole mixed with Propylene glycol and Macrogol. This was called the 3 Mix MP paste.[11],[12],[13],[14],[15],[16],[17]
Table 2: Landmark studies that led to the development of lesion sterilization and tissue repair concept

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  Other Terminologies Used for Lesion Sterilization and Tissue Repair Top

  • Since the technique did not warrant the use of instruments for preparing the root canal, it was called as non-instrumentation endodontic treatment[11]
  • LSTR 3 Mix MP Save Pulp therapy[12]
  • 3 Mix MP therapy.[12]

  Composition of the 3 Mix Mp Paste Top

  • Antibiotics

    • Ciprofloxacin-200 mg
    • Metronidazole– 500 mg
    • Minocycline– 100 mg.

  • Vehicle

    • Macrogol
    • Propylene glycol.[7]

  Method of Preparation of 3-Mix Mp Paste Top

  • Removal of enteric coating/capsule of each medication
  • Pulverization of the each of the drug, carried out using a pestle and mortar and was stored in an air tight porcelain container to avoid the exposure to moisture and light
  • The pulverized powders are stored at a temperature of 16°C
  • However the powder should be allowed to be cooled to the room temperature before initiating the preparation of 3Mix MP paste
  • The powders are mixed in the proportion of:

    • 1:1:1 by volume (Hoshino et al.)[13] (or)
    • 1:3:3 by volume (Takushige et al.)[11]

  • The vehicle is prepared by mixing propylene glycol and macrogol in 1:1 ratio by volume[7],[11]
  • Then the prepared antibiotic powder is mixed with the prepared vehicle in the ratio of 7:1 by volume[12]
  • The antibiotic powder mix was used within 1 month since the time of preparation in a study done by Takushige et al.[12]

  Modifications of the 3-Mix Mp Paste Top

Modifications of the antibiotic used

  • Sato et al.:

    • Because of the concerns regarding the staining caused by minocycline, Sato et al., proposed a modification of the traditional 3Mix MP paste where the minocycline component is replaced by other drugs and they were found to be equally effective
    • The drugs that were tried are as follows:
    • Amoxicillin (aminopenicillin)
    • Cefaclor (cephalosporin)
    • Fosfomycin
    • Rokitamycin (macrolide)
    • Rifampicin.[14],[15],[16],[17]

  • Pinky et al.:

    • Considering the fact that ornidazole has better properties as compared to metronidazole (greater efficacy, slow metabolism and thereby Long duration of action), in a study done by Pinky et al., metronidazole was replaced by ornidazole
    • The three medications, ciprofloxacin, ornidazole and minocycline were pulverized and mixed in a ratio of 1:3:3 and this mixture was added to propylene glycol to form an ointment
    • This paste had similar antibacterial efficacy as compared to the ciprofloxacin, metronidazole and minocycline. When used in necrotic primary teeth.[18]

  • Jaya et al.:

    • Combined three drugs namely, ciprofloxacin, tinidazole and minocycline in 1:3:3 ratio and mixed with propylene glycol and macrogol. The mixture was comparable to the traditional 3Mix MP paste with regards to antimicrobial efficacy when used in deciduous teeth showing physiological root resorption.[19]

  • Burrus et al.:

    • Tried a combination of Metronidazole, Ciprofloxacin and Clindamycin. Clindamycin was used instead of Minocycline due to its effectiveness against Streptococci and anaerobes. In addition to this Iodoform was used to make it radiopaque.[20]

  • Lokade et al.:

    • Combined three antibacterial agents namely, ciprofloxacin (500 mg), ornidazole (500 mg) and cefaclor (250 mg) in the ratio of 1:1:1 by volume
    • Propylene glycol and macrogol were mixed in 1:1 ratio by volume
    • A ratio of 7:1 by volume was used for mixing the powder and vehicle.[21]

The concept of double antibiotic paste

The prime concern regarding the use of triple antibiotic paste is the discoloration caused by minocycline. To overcome this, alternative medications such as clindamycin and cefaclor have been proposed.[20],[21] But, recent studies have shown that, double antibiotic paste has similar antimicrobial activity compared to that of a triple antibiotic paste. Sabrah et al., in theirin vitro study comparing the efficacy of Triple antibiotic paste and Double antibiotic paste concluded that both had equal efficacy against Enterococcus faecalis and Porphyromonas gingivalis. A similar study by Algarni et al. compared the antimicrobial efficacy of methylcellulose based pastes of triple antibiotic paste (ciprofloxacin, mteronidazole, and clindamycin) and double antibiotic paste (ciprofloxacin and metronidazole). It was found that both were equally effective against E. faecalis and P. gingivalis. However further studies are warranted to confirm theirin vivo efficacy in primary teeth.[22],[23]

  Modifications of the Vehicle Used Top

Originally Takushige (1998) used propylene glycol and macrogol as vehicle in 1:1 ratio by volume. But several authors have modified the vehicle in their studies.

  • Takushige et al. compared the combination of macrogol and propylene glycol as vehicle in one group and the other group had a sealer as vehicle. It was found that propylene glycol has better penetration into dentin when compared to sealer[12]
  • Pinky et al. and Nanda et al., in their study utilized only propylene glycol as the vehicle[18],[24]
  • Dutta et al., used distilled water as vehicle in one group and 2% chlorhexidine gluconate as vehicle in another group in their study. Maximum bacterial inhibition was observed when the antibiotic powder was mixed with chlorhexidine gluconate.[25]

  Indications for Lesion Sterilization and Tissue Repair Therapy Top

  • Primary teeth with irreversible pulpitis which are characterized by:

    • Deep carious lesions with spontaneous pain
    • Carious lesion extending to the pulp either clinically/radiographically.

  • Chronic pulpitis showing clinical signs of gingival swelling/sinus tract
  • Pulpitis cases in which there is extensive root resorption and which are contraindicated for conventional pulpectomy
  • Presence of furcation radiolucency.

  Contra-Indications for Lesion Sterilization and Tissue Repair Therapy Top

  • A known history of allergy to any of the constituent medication of the 3 Mix MP paste
  • Primary teeth nearing exfoliation
  • Perforation of the pulpal floor
  • Teeth with excessive coronal structure breakdown in which an adequate coronal seal is not feasible.[26]

  Clinical Procedure for Lesion Sterilization and Tissue Repair Therapy Top

  • Access opening is performed which is followed by removal of old restoration and necrotic pulp if any
  • The access cavity walls are treated with 37% phosphoric acid
  • To facilitate the placement of 3 Mix MP paste, a medication cavity is created which measures 1 mm in width and 2 mm in depth
  • If hemorrhage is present, it is controlled using cotton pellet dipped in 10% sodium hypochlorite
  • In cases where preparation of medication cavity is not feasible (excessive physiologic resorption), the entire pulpal floor is filled with the 3 Mix MP paste
  • Glass ionomer cement is used to cover the paste on to which a resin inlay is placed as a reinforcement.[11]

  Advantages Top

  • Relatively simple and easy when compared to conventional pulp therapy (Less technique sensitive)
  • Decreased chair-time (single visit)
  • Noninstrumentation technique. Obturation of the canals is not needed so re-treatment if necessary is also easier to perform
  • Economical
  • Primary teeth which are not ideal for conventional pulpectomy treatment and those that warrant extraction can be treated using LSTR (Teeth with peri–radicular involvement and extensive root resorption).[11],[12],[27]

  Disadvantages Top

  • Systemic absorption and drug resistance of the drugs used in LSTR therapy has not been evaluated. The long– term effects of the drugs used need to be evaluated
  • Standardized measuring systems for pulverizing and proportioning the antibiotics need to be formulated to avoid over use of antibiotics
  • Minocycline is known to cause discoloration of the enamel. However this can be replaced by using clindamycin
  • The original 3 Mix Paste appears radiolucent in radiographs. This can be overcome by addition of Iodoform to the mixture.[26]

  Recent Studies on Lesion Sterilization and Tissue Repair Top

The recent studies on LSTR have been enumerated below [Table 3].
Table 3: Recent studies on lesion sterilization and tissue repair

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  Scope for Future Work Top

The issues that need to be addressed in the LSTR technique include:

  • A standardization regarding the dose of drugs used in the 3 Mix antibiotic combination as well as specific methods to proportion the drugs while pulverizing and mixing is required
  • It has been said that Ciprofloxacin has side effects in pediatric patients but it is considered to be safe for children in the age group between 3 and 12 years when used according to recommended dosage (for patients weighing >40 kg– twice daily dose of 750 mg; <40 kg– twice daily dose of 500 mg and <20 kg– twice daily dose of 250 mg). But, standard measuring systems should be formulated for precise pulverization and proportioning of the drug[15]
  • When using antibiotics for topical usage, systemic absorption and drug resistance are of primary concern. Although it is claimed that the small quantity of drug used in the 3 Mix paste (<1 mg), is safe and causes neither systemic toxicity nor drug resistance, long-term studies are required to validate the claim.[15]

  Conclusion Top

Pulp therapy in the form of pulpotomy/pulpectomy is the preferred treatment modality in case of carious lesions of primary teeth involving the pulp. However, certain factors such as extensive root resorption and/or presence of furcal radiolucency may contradict pulpectomy and extraction is the only treatment in such cases. If an extraction is performed a space maintainer should be given to prevent any space loss that might occur. LSTR seems to be a promising alternative for primary teeth in which pulpectomy has been contra-indicated and extraction is warranted. Also, in medical conditions where several precautions need to be taken prior to extractions (blood dyscrasias), LSTR being a relatively simpler and economical alternative can be considered as an option[31].

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Conflicts of interest

There are no conflicts of interest.

  References Top

Coll JA, Sadrian R. Predicting pulpectomy success and its relationship to exfoliation and succedaneous dentition. Pediatr Dent 1996;18:57-63.  Back to cited text no. 1
Tchaou WS, Turng BF, Minah GE, Coll JA.In vitro inhibition of bacteria from root canals of primary teeth by various dental materials. Pediatr Dent 1995;17:351-5.  Back to cited text no. 2
Verma R, Sharma DS, Pathak AK. Antibacterial efficacy of pastes against E faecalis in primary root dentin: A confocal microscope study. J Clin Pediatr Dent 2015;39:247-54.  Back to cited text no. 3
Hegde S, Lala PK, Dinesh RB, Shubha AB. Anin vitro evaluation of antimicrobial efficacy of primary root canal filling materials. J Clin Pediatr Dent 2012;37:59-64.  Back to cited text no. 4
Jha M, Patil SD, Sevekar S, Jogani V, Shingare P. Pediatric obturating materials and techniques. JCD 2011;1:27-32.  Back to cited text no. 5
Pinkham JR, Casamassimo PS, McTigue DJ, Fields HW Jr., Nowak AJ. Pediatric Dentistry: Infancy through Adolescence. 4th ed. St. Louis: Elsevier Saunders; 2005. p. 375-93.  Back to cited text no. 6
Parasuraman VR, Mujlibhai BS. 3 Mix MP in endodontics. IOSR J Dent Med Sci 2012;3:36-45.  Back to cited text no. 7
Bansal R, Jain A. Overview on the current antibiotic containing agents used in endodontics. N Am J Med Sci 2014;6:351-8.  Back to cited text no. 8
Amorim Lde F, Toledo OA, Estrela CR, Decurcio Dde A, Estrela C. Antimicrobial analysis of different root canal filling pastes used in pediatric dentistry by two experimental methods. Braz Dent J 2006;17:317-22.  Back to cited text no. 9
Mello-Moura AC, Fanaro J, Nicoletti MA, Mendes FM, Wanderley MT, Guedes-Pinto AC. Variability in the proportion of components of iodoform-based Guedes-Pinto paste mixed by dental students and pediatric dentists. Indian J Dent Res 2011;22:781-5.  Back to cited text no. 10
  [Full text]  
Takushige T, Cruz EV, Asgor Moral A, Hoshino E. Endodontic treatment of primary teeth using a combination of antibacterial drugs. Int Endod J 2004;37:132-8.  Back to cited text no. 11
Takushige T, Hataoka H, Ando M, Hoshino E. Endodontic retreatment using 3 Mix-MP without removal of previous root canal obturation. J LSTR Ther 2009;8:3-7.  Back to cited text no. 12
Hoshino E, Kota K, Sato M, Iwaku M. Bactericidal efficacy of metronidazole against bacteria of human carious dentin in vitro. Caries Res 1988;22:280-2.  Back to cited text no. 13
Sato T, Hoshino E, Kota K, Iwaku M, Noda T. Bactericidal efficacy of a mixture of ciprofloxacin, metronidazole, minocycline and rifampicin against bacteria of carious and endodontic lesions of human deciduous teeth in vitro. Microbiol Ecol Health Dis 1992;5:171-7.  Back to cited text no. 14
Sato T, Hoshino E, Uematsu H, Noda T.In vitro antimicrobial susceptibility to combinations of drugs on bacteria from carious and endodontic lesions of human deciduous teeth. Oral Microbiol Immunol 1993;8:172-6.  Back to cited text no. 15
Sato I, Ando-Kurihara N, Kota K, Iwaku M, Hoshino E. Sterilization of infected root-canal dentine by topical application of a mixture of ciprofloxacin, metronidazole and minocycline in situ. Int Endod J 1996;29:118-24.  Back to cited text no. 16
Hoshino E, Kurihara-Ando N, Sato I, Uematsu H, Sato M, Kota K, et al. In-vitro antibacterial susceptibility of bacteria taken from infected root dentine to a mixture of ciprofloxacin, metronidazole and minocycline. Int Endod J 1996;29:125-30.  Back to cited text no. 17
Pinky C, Shashibhushan KK, Subbareddy VV. Endodontic treatment of necrosed primary teeth using two different combinations of antibacterial drugs: Anin vivo study. J Indian Soc Pedod Prev Dent 2011;29:121-7.  Back to cited text no. 18
[PUBMED]  [Full text]  
Jaya AR, Praveen P, Anantharaj A, Venkataraghavan K, Rani PS.In vivo evaluation of lesion sterilization and tissue repair in primary teeth pulp therapy using two antibiotic drug combinations. J Clin Pediatr Dent 2012;37:189-91.  Back to cited text no. 19
Burrus D, Barbeau L, Hodgson B. Treatment of abscessed primary molars utilizing lesion sterilization and tissue repair: Literature review and report of three cases. Pediatr Dent 2014;36:240-4.  Back to cited text no. 20
Lokade A, Thakur S, Singhal P, Chauhan D, Jayam C. Comparative evaluation of clinical and radiographic success of three different lesion sterilization and tissue repair techniques as treatment options in primary molars requiring pulpectomy: Anin vivo and study. J Indian Soc Pedod Prev Dent 2019;37:185-91.  Back to cited text no. 21
[PUBMED]  [Full text]  
Sabrah AH, Yassen GH, Gregory RL. Effectiveness of antibiotic medicaments against biofilm formation of Enterococcus faecalis and Porphyromonas gingivalis. J Endod 2013;39:1385-9.  Back to cited text no. 22
Algarni AA, Yassen GH, Gregory RL. Inhibitory effect of gels loaded with a low concentration of antibiotics against biofilm formation by Enterococcus faecalis and Porphyromonas gingivalis. J Oral Sci 2015;57:213-8.  Back to cited text no. 23
Nanda R, Koul M, Srivastava S, Upadhyay V, Dwivedi R. Clinical evaluation of 3 Mix and Other Mix in non-instrumental endodontic treatment of necrosed primary teeth. J Oral Biol Craniofac Res 2014;4:114-9.  Back to cited text no. 24
Dutta B, Dhull KS, Das D, Samir PV, Verma RK, Singh N. Evaluation of antimicrobial efficacy of various intracanal medicaments in primary teeth: Anin vivo study. Int J Clin Pediatr Dent 2017;10:267-71.  Back to cited text no. 25
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Takushige T, Cruz EV, Moral MA, Hoshino E. Non-surgical treatment of pulpitis, including those with history of spontaneous pain, using a combination of antibacterial drugs. J LSTR Ther 2008;7:1-5.  Back to cited text no. 27
Grewal N, Sharma N, Chawla S. Comparison of resorption rate of primary teeth treated with alternative lesion sterilization and tissue repair and conventional endodontic treatment: Anin vivo randomized clinical trial. J Indian Soc Pedod Prev Dent 2018;36:262-7.  Back to cited text no. 28
[PUBMED]  [Full text]  
Parakh K, Shetty RM. Evaluation of paste containing gentamicin, amoxicillin and metronidazole in endodontic treatment of primary molars in vivo. Chin J Dent Res 2019;22:57-64.  Back to cited text no. 29
Arangannal P, Muthiah G, Jeevarathan J, Sankar P. Lesion sterilization and tissue repair in nonvital primary teeth: Anin vivo study. Contemp Clin Dent 2019;10:31-5.  Back to cited text no. 30
[PUBMED]  [Full text]  
Rafatjou R, Yousefimashouf R, Farhadian M, Afzalsoltani S. Evaluation of the antimicrobial efficacy of two combinations of drugs on bacteria taken from infected primary teeth (in vitro). Eur Arch Paediatr Dent 2019;20:609-15.  Back to cited text no. 31


  [Figure 1]

  [Table 1], [Table 2], [Table 3]


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