An in vitro dye leakage study was conducted on one hundred and twenty single rooted human teeth with single root canals to assess the relative microleakage of three retrograde filling materials namely light cure calcium hydroxide, cermet and silver amalgam with and without bevel. Specific retrograde cavities were made and filled. The extent of penetration of 2% methylene blue dye was measured by a travelling microscope. The results showed that cermet had statistically lesser leakage as compared to light cure calcium hydroxide and silver amalgam. There was signifi­cant increase in the leakage as the amount of bevel increased.

The clinical significance of increasing the depth of cure of posterior composites in the cervical region of a class 11 cavity has lead to the introduction of light transmit­ting wedges, matrices and cones. This study was conducted to evaluate the efficiency of existing transparent wedges and an innovative fibre optic cable. Simulate class IIcavities were prepared in brass blocks and restored with four popular posterior com­posite resins having an uniform vita shade. With the standardized curing time of 60s, the materials were polymerized by three different techniques (1) Conventionalmethod (2) Using fibre optic cables (3) Using light transmitting wedges. The speci­mens were subjected to vickers hardness test using shimadzu microharness meter after 1 hour and 24 hours. The results were tabulated and evaluated for any statistically significant variation in the depth of cure.

"Cleanliness is next to Godliness" This axiom very well applies for endodontic therapy also. Therefore to achieve clinical success in endodontic therapy, the canal must be debrided thoroughly.Although the use of Lasers in endodontics was first reported some time ago, it is only recently that the potential of this technology has been recognized.Twenty freshly extracted single rooted teeth were exposed to Nd-YAG Laser for preparation of root canal and to observe its affect on the adjoining tissues.Teeth were later on sectioned longitudinally and examined under the SEM. Improved cleanliness of canals and fusion of dentinal tubules were observed.

To master the art of endodontics requires a complete knowledge of morphol­ogy, principles of debridement and obturation. The failures in endodontic treat­ment has long been intriguing the dental surgeon because of insufficient knowledge of the morphology of root canal system. One of the highest failure rates have been reported in mandibular first premolar. The purpose of this study was to conduct a detailed investigation of root canal morphology of mandibular first premolar using different methods i.e. radiographs, sections and making the teeth transparent. The shape of the root canal system, type of canal configuration, levels at which multiple canals furcate and other variations were studied in detail so as to achieve maximum success rate in the endodontic treatment of this tooth.