Dental caries is the most prevalent chronic disease in the global population. It is characterised by the destruction of inorganic and dissolution of organic material from tooth structure. The conventional dentistry approach to caries treatment has been removing diseased tissue and replacing it with a dental restorative material. Mechanical caries removal traditionally involves the use of conventional tungsten carbide or round steel burs and hand instruments. The disadvantages of these methods are overpreparation of cavities, pain sensitivity and possible damage to the pulp. Since the dentistry has advanced so much in 21^st century that G.V.Blacks “Extension for prevention” has transformed to “Prevention for Extension.” With the advent of adhesive materials and greater understanding of the disease process we are moving into era of  Minimal intervention dentistry.The newer method for caries removal which follows the principle of minimally invasive dentistry has developed recently since last decades.These include laser, chemo-mechanical method, air abrasion, air polishing, ultrasonic, ozone method, polymer burs and enzymes.

The aim of the study is to compare the caries removal efficacy in terms of microbiological assessment and efficiency in terms of time taken by Tungsten Carbide Bur No.330,Polymer bur,BRIX 3000 and ErCr:YSGG Laser.

INCLUSION CRITERIA:

1)Class 1 dentinal caries with broad occlusal cavitated lesion on permanent molars. (2)Radiographically carious lesion has to be confined to outer dentin of occlusal surface. (3)Patient aged between 18-40 years old. (4)Teeth with intact buccal/lingual surface. 5)RDT ≥ 1.5 mm.

EXCLUSION CRITERIA:

1)Permanent molars with clinical and radiological signs and symptoms of pulpal and periapical lesions. (2)Teeth with any developmental anomaly. (3)Teeth with proximal caries and pulpal involvement. (4)Teeth with previous restoration and fractured crown. (5)Presence of white spot lesions. (6)Hypoplastic or hypomineralized teeth.

A total of 60 patients between the age group 18 to 40 years fulfilling the inclusion criteria will be included in the study after obtaining informed consent. Before starting the procedure, preoperative radiograph will be taken and RDT will be determined. All potential participants will be selected randomly and will be divided into 4 groups depending on caries excavation methods. Rubber Dam will be used for isolation of the respective tooth. Local anesthesia will be given if the patient experiences pain or sensitivity during caries excavation. Caries excavation will be done with the following methods mentioned above. Time taken will be measured using a stopwatch from the beginning of caries removal to confirmation of complete excavation of caries clinically. For Microbiological Evaluation two samples of carious material will be collected (one before caries excavation and one after) in Eppendorf tubes that contains saline. They will be transported to the laboratory within 2 hrs. The samples will then be placed on blood agar plates and will be incubated aerobically at 37ºC for 48 hrs. Using the Digital Colony Counter total number of colonies formed will be determined and expressed as CFU/ml. Colony forming units per sample will be estimated before and after the treatment and will then be processed according to S.O.P of RRMCH.