The bactericidal effect of Argon ion laser (CW, 5W, The coherent, INNOVA 400-10 series ion laser) on 3 aerobic bacteria : Staphylococcus aureus, Entrococcus faecalis and Pseudomonas aeruginosa was investigated. 10⁶ CFU/ml of each of these bacteria were exposed to laser radiation for various time intervals and checked microbiologically to determine lethal energy does (LED). This energy was then exposed in intervals, summation of which was equal to LED. It was found that the LED for S.aureus was 3.6 KJ/cm², E.faecalis 3.8 kJ/cm², and Ps. aeruginosa 6.6 KJ/cm². There was specific lethal threshold energy density and it must be delivered in one shot.

The previous article dealt with lethal dose of Argon-ion laser radiation to kill three organisms. It determined the energy density and the time required to kill S. aureus, E. tecalis and Ps. aeruginosa. It also determined that the lethal dose when divided into 2-3 parts was ineffective to achieve 100% kill of the bacteria. This article discusses the mechanism of action of Argon-ion laser in killing the bacteria and determines the optimum concentration of bacteria (CFU/ml²) required to achieve the kill.

Furcation perforations were created in pulpal floor of 60 recently extracted molars and repaired with light cure glass ionomer, light cure composite resin, and silver amalgam with or without Gelfoam barrier. Teeth were immersed in 2% methelerie blue for 2 weeks and sectioned longitudinally and dye penetration was measured by a sterio microscope. The light cure glass ionomer showed minimum dye penetration (24%) followed by silver amalgam (34%) in barrier group. In non barrier group, both Glass ionomer and composite resin revealed 100% leakage while in silver amalgam, dye penetration was only 56%.

Periapical status of one hundred and twenty six posterior teeth treated endodontically approximately one year back were evaluated clinically and radiologically in relation to the technical quality of root filling and the coronal restoration. Clinically all but 4 teeth were symptom free, however, radiologically, 55.6% of the teeth had periradicular inflammation. Absence of periradicular inflammation (API) was evident in 100% cases where both root filling and coronal restoration were good. API was 53.8% where root filling was good and the coronal restoration was poor. Statistically, the correlation of good endodontic filling and good coronal restoration with absence of periradicular inflammation was highly significant. The results of this study indicate that the coronal restoration is of critical importance and only good endodontic filling alone is not sufficient for better results

The purpose of this study was to find out the effects of the presence and absence of the smeard layer upon penetration of root canal sealers into the dentinal tubules. Penetration of Zinc oxide eugenol, Kalzinol and Sealapex was studied with the help of SEM, in the coronal, middle and apical thirds of the root canal after filling the root canals both in the presence and absence of the smeard layer. Presence of the smeared layer did not allow the sealers to enter the dentinal tubules. After the removal of the smeared layer, Zinc oxide eugenol penetrated the dentinal tubules in coronal and middle thirds and Sealapex in coronal third only. Kalzinol did not display any penetration. No sealer was able to penetrate the apical dentinal tubules.