The influence of cortical bone perforation on guided bone regeneration in humans.

The purpose of this study was to evaluate the effect of cortical bone perforation on angiogenesis and osteogenesis of the augmented ridge in guided bone regeneration. Eighteen patients who had osseous defects in the mandible were selected. In the test group (n=9), alveolar cortical bone in the area of regeneration was perforated. No decortication was performed in the control group (n=9). Subsequently, defects were augmented by guided bone regeneration using resorbable membrane and bovine bone. After a healing period of 7 months, trephine cores were harvested for histological and histomorphometric analysis of the grafted areas. Histomorphometry demonstrated that the amount of newly formed bone in the test group (27.8%) was greater than that in the control group (25.3%), but the difference was not statistically significant (P=0.13). However, the mean number of microvessels in the test group was significantly higher than that in the control group (P=0.01). This study found that cortical bone perforation favourably affects the amount of new bone formation in the grafted sites after 7 months of healing. Cortical bone perforation significantly increase number of new vessels (angiogenesis) of the regenerated bone. Further randomized clinical trials are required to confirm these results.

Dental students' attitudes toward smoking cessation guidelines.

Dentists can be effective in helping their patients achieve smoking cessation. To plan a didactic program, we explored the smoking cessation attitudes and practices of dental students and identified barriers to service provision in the dental setting. We assessed 244 fourth-year dental students at New York University College of Dentistry through a self-report survey. The instrument included a twenty-nine-item measure assessing attitudes towards tobacco-use counseling and adherence to National Cancer Institute tobacco cessation guidelines. The survey also assessed demographics, tobacco use history, and level of preparation to provide services. Generally, students endorsed tobacco prevention practices, but perceived barriers to service provision. Students provided counseling inconsistently, with 69 percent asking about smoking, 58 percent advising cessation, 24 percent offering assistance, and 22 percent providing followup on a routine basis. Those who provided more counseling were more likely to have undergone formal training in smoking cessation, did not feel time was a barrier to counseling, and had more favorable beliefs about dentists' role in promoting smoking cessation. Study findings indicate great receptivity among students as well as a critical need and opportunity to include comprehensive cessation counseling training in the dental curriculum.

Conjugal transfer of broad-host-range incompatibility group P and Q plasmids from Escherichia coli to Actinobacillus actinomycetemcomitans.

The first example of conjugal transfer of DNA from Escherichia coli to the periodontal pathogen Actinobacillus actinomycetemcomitans is presented. Derivatives of the incompatibility group P (IncP) plasmid RK2 successfully transferred from an E. coli donor to an A. actinomycetemcomitans recipient. The resulting A. actinomycetemcomitans transconjugants transferred the plasmids back to E. coli recipients. The IncP transfer functions were also used in trans to mobilize the IncQ plasmid pBK1 from E. coli to A. actinomycetemcomitans. The IncP and IncQ plasmids both transferred into A. actinomycetemcomitans at high frequencies (0.3 to 0.5 transconjugants per donor) and showed no gross deletions, insertions, or rearrangements. Determinations of MICs of various antibiotics for the A. actinomycetemcomitans transconjugant strains demonstrated the expression of ampicillin, chloramphenicol, and kanamycin resistance determinants.