The aim of this study is to determine whether the success rate of pulp therapy undergone on primary molars with signs and symptoms of odontogenic infection that may render them indicated for extraction will improve with the use of the Simvastatin alone, the Tri-Antibiotic Mix alone or when in combination together 3Mixstatin as a component in the root filling material.

A clinical situation will often present itself where primary teeth under radiographic examination show inter-radicular or periapical root resorption, perforation of coronal third of roots and/or loss of bone support as a result of infective or inflammatory conditions. Pathologic root resorption is the most common cause of premature tooth loss in primary dentition. The reason for that may be the high content of undifferentiated mesenchymal cells, which may give rise to odontoclastic cells in response to either the caries process or the pulp-capping materials, resulting in the exaggerated inflammatory response and consequently internal resorption in primary teeth. It would make sense to utilize the rich supply of undifferentiated mesenchymal cells towards regeneration of remaining dental tissues.

Antibiotic Mix as an intracanal medicament

In recent years, the Cariology Research Unit of Niigata University School of Dentistry has developed the concept of lesion sterilization and tissue repair (LSTR) therapy that employed a mixture of antibacterial drugs for disinfection. Repair of damaged tissues can be expected if lesions are disinfected. This procedure uses a mixture of three antibacterial drugs (3Mix MP) as a root canal medicament to eliminate the remaining bacteria in endodontic lesions. The medicament consists of metronidazole, ciprofloxacin and minocycline - with macrogol (M) as the ointment base and propylene glycol (P) as the carrier Alone, none of these drugs resulted in complete elimination of the bacteria. However, in combination, these drugs were able to consistently sterilize all samples.

Although a local antibiotic medication in endodontics offers many advantages, this mode has some drawbacks, including development of bacterial resistant strains. That is a major concern and may lead to the transfer of resistance genes from antibiotic-resistant to antibiotic-susceptible microorganisms. Other drawbacks include allergic reactions inhibition of angiogenesis , and tooth staining or discoloration particularly with Minocycline. More importantly is that although the concept of Lesion sterilization and tissue repair (LSTR) therapy is that it provides an efficient and predictable disinfection, through 3 Mix on a local level and providing the suitable environment for tissues to heal, it does not in itself have any anti-inflammatory nor regenerative potential. Statins may provide these two benefit.

Choice of comparator Statins are structural analogs of HMG-CoA (3hydroxy-3-methylglutaryl-coenzyme A). These drugs are the first-line for hyperlipidemia and it has been recognized to be a safe and low-priced drug as a result of its worldwide longtime usage. Moreover, statins have multiple functions including anti-inflammation, induction of angiogenesis and improvement of the vascular endothelial cell function. Another interesting and important function of statin is its effect on bone formation. It has been reported that several statins such as simvastatin and lovastatin have anabolic effects on bone metabolism at in vitro and in vivo studies. They promote mineralization in non-mineralizing osteoblasts through induction of BMP-2 and osteocalcin. Local application of simvastatin gel has shown to stimulate the regeneration of alveolar bone defects Statins have an anti-inflammatory effect. They act by decreasing the production of interleukin-6 and interleukin-8 and may also improve the function of odontoblasts, thus dentin formation.

3 Mixstatin as an intracanal medicament

Often, different chemicals or drugs are combination in a cocktail in an attempt to elicit variety of effects with a single application.

Aminabadi et al combined the above-mentioned techniques by adding simvastatin powder to the tri-antibiotic mix (3Mix) and proposed the term "3Mixtatin", (an acronym of 3Mix and simvastatin) with the aims of suppressing bacteria, preventing pulp inflammation, and inducing hard tissue formation. His study population involved poor prognosis primary molars with advanced root resorption and/or pulpal floor perforation.

When compared with MTA, radio graphic and clinical healing occurred more successfully following 3Mixtatin treatment within a 24-month study period 96.8% success rate both clinically and radiographically. 3Mixstatin, a previously unstudied combination was applied, lead to preservation of the primary teeth that were otherwise indicated for extraction according to current guidelines. It may lead to a paradigm shift in the treatment of primary teeth in the future.

Inclusion Criteria:

Patients:

1. Young cooperative patients with no history of systemic disease that may contraindicate pulp therapy
2. Age range 4-6 years.
3. Patient has at least one restorable primary molar that exhibits signs and symptoms of odontogenic infection with inflammatory root resorption and require pulpectomy,
4. Patient's parents are willing to participate in this study and will be able to follow up Clinical & Radiographic Criteria for Case Selection Signs and symptoms of irreversible pulpitis as well as inter-radicular, or periapical root resorption as a result of infective or inflammatory conditions that may render the tooth hopeless and indicated for extraction

Clinical Criteria (include):

1. Spontaneous pain
2. Intraoral Abscess
3. Extra oral Abscess
4. Tender to percussion
5. Presence of abnormal mobility other than that associated with exfoliation

Radiographic Criteria include:

1. Radiolucency in furcation area 2. Periapical root resorption or excessive bone destruction and/or perforation in coronal third of roots as a result of infective or inflammatory conditions.

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Exclusion Criteria:

• Patients with systemic disease 2. Patients who cannot attend follow up. 3. Primary molars that are unrestorable 4. Primary molars exhibiting pathology of permanent tooth follicle

Every participant will grasp an opaque sealed envelop from a box after diagnosis of the case. Being opaque and sealed ensures allocation concealment. Envelopes have been assigned to RN who is not involved in neither the diagnosis nor the treatment phases of the cases.