Bone Dimensional Change Following Immediate Implant Placement in Posterior Teeth with CBCT: A 6-Month Prospective Clinical Study

This prospective clinical study aimed to evaluate the peri-implant hard tissue dimensional change at 6 months of immediate implant placement with bone graft materials in the posterior area using cone-beam computed tomography (CBCT). Twelve dental implants were placed concurrently following tooth extraction in the posterior area and filled with xenograft particles. The CBCT images were taken immediately after surgical procedures and then at 6 months follow-up. To evaluate the hard tissue changes, the vertical and horizontal bone thickness were analyzed and measured using ImageJ software. Paired t-test or Wilcoxon match-pair signed-rank test was done to analyze the changes of hard tissue values at the same level between immediately and 6 months following immediate implant placement. Independent t-test or Mann–Whitney U test was used to analyze the dimensional change in the vertical and horizontal direction in buccal and lingual aspects. The level of significance was set at p value = 0.05. All implants were successfully osseointegrated. At 6 months follow-up, the vertical bone change at the buccal aspect was −0.69 mm and at the lingual aspect −0.39 mm. For horizontal bone thickness, the bone dimensional changes at 0, 1, 5, and 9 mm levels from the implant platform were −0.62 mm, −0.70 mm, −0.24 mm, and −0.22 mm, respectively. A significant bone reduction was observed in all measurement levels during the 6 months after implant placement (p value < 0.05). It was noted that even with bone grafting, a decrease in bone thickness was seen following the immediate implant placement. Therefore, this technique can be an alternative method to place the implant in the posterior area.     

Ultraviolet inactivation of feline calicivirus,human enteric viruses and coliphages

Norwalk and Norwalk-like viruses (NLV) are major causes of food- and water-related disease in the United States. There is no host cell line in which the NLV can be tested for infectivity. Feline calicivirus (FCV) and NLV both belong to the family Caliciviridae. FCV can be assayed for infectivity in the Crandell Reese feline kidney cell line, so FCV serves as a surrogate for NLV. This study is the first report of UV inactivation of FCV and also of using the plaque technique, in contrast to the 50% tissue culture infectious dose end point technique, to determine the FCV infectivity titer. The infectivity titers (log10 plaque-forming units/mL) of UV-inactivated FCV, hepatitis A virus (HAV), poliovirus type 1 (PV1) and two small, round coliphages were plotted as a function of UV dose and analyzed by regression analysis and analysis of variance. These fitted straight-line curves represent exponential inactivation, so UV inactivation can be said to show "one-hit kinetics." The decimal inactivation doses of UV for FCV, HAV, PV1, MS2 and phiX174 were 47.85, 36.50, 24.10, 23.04 and 15.48 mW s/cm2, respectively. FCV appears to be the most UV resistant among the tested viruses.