The mechanism of action of chlorhexidine

Controversy exists concerning the mode of action of chlorhexidine in plaque inhibition. This study attempted to determine whether an oral reservoir of chlorhexidine was necessary for plaque inhibition. Plaque growth on enamel under the influence of topically applied or rinsed chlorhexidine was closely monitored by clinical scoring, bacterial culturing and scanning electron microscopy. Thus, 3 subjects wore removable acrylic appliances containing enamel inserts. In the first regimen, inserts on one side of the appliances were exposed to 0.2% chlorhexidine and on the other, water for 1 min twice a day for 14 days. In the second regimen, subjects rinsed with 0.2% chlorhexidine for 1 min twice a day for 14 days with the appliances in situ. Results demonstrated that plaque growth assessed by the 3 study methods was very small on chlorhexidine-treated inserts by comparison with water-treated specimens. Importantly, inserts treated with chlorhexidine topically or by rinsing could not be distinguished by any method of evaluation. It is concluded that chlorhexidine achieves plaque inhibition as a result of an immediate bactericidal action during the time of application and a prolonged bacteriostatic action as a result of adsorption to the pellicle coated enamel surface. Consistent with other clinical studies, it is apparent that a progressively desorbing oral reservoir of antiseptic is not the mechanism by which chlorhexidine achieves plaque inhibition on teeth.     

Oral diseases, mycology and periodontal microbiology of HIV-1-infected women

HIV-1 infection is increasing more rapidly among heterosexual women. Relatively limited information is available on HIV-related oral pathoses in these individuals. To gain insight into the type and occurrence of oral lesions in this population, 25 HIV-1 infected women including asymptomatic, symptomatic and AIDS patients were examined clinically and sampled for detection of oral yeast and characterization of their subgingival microbial flora. Sixty percent of the subjects were African-American, with 80% infected via heterosexual contact. Oral candidiasis was the most common nonperiodontal oral lesion, observed in 44% of the patients. Oral yeast was cultured from all women with candidiasis and 76% of the total subjects. Oral hairy leukoplakia was clinically diagnosed in 16% of the subjects. Clinically mild to moderate gingivitis and periodontitis were observed in 84% and 52% of the patients, respectively. Candidiasis and the presence of cultivable yeast were observed in patients with low, intermediate, and high CD4⁺ T lymphocyte numbers. Plaque samples were collected from each subject and enumerated by predominant cultivable methods, selective media and microscopy. No differences were detected in the microflora associated with seropositive women with existing periodontitis relative to those without periodontitis or to seronegative women with periodontitis. Candidiasis was the most notable oral clinical manifestation in the HIV-1-infected women and may be a useful clinical indicator of early immune dysfunction mediated by HIV-1.     

A mathematical model for post-irradiation hardening of photoactivated composite resins

A generalized mathematical model for the post-irradiation hardness of photoactivated resins is presented. This model describes a ratio of hardness values as a function of time after irradiation. The low error and generalized character of the model indicate similarities in the post-irradiation hardening of adequately irradiated resins. Using a ratio of hardness at the bottom surface to the final hardness of the top surface, an inadequately irradiated resin can be identified by deviation from the generalized model. Such deviations are noted throughout the hardening process and are recommended as a means of readily identifying deficient photoactivation.     

Correction of mandibular prognathism by mandibular setback and advancement genioplasty

The goal of surgical-orthodontic treatment of mandibular prognathism is to achieve maximum function, esthetics and stability. These objectives were achieved in 10 adults who manifested a specific type of mandibular prognathism. The patient group under study, who manifested a relatively contour deficient chin and prominent lower lip, and class III malocclusion, was treated by orthodontics and mandibular setback in concert with advancement genioplasty. The advancement genioplasty technique was accomplished by maintaining as much soft tissue pedicle as possible to the repositioned chin. A near one-to-one ratio of soft tissue-to-osseous change was achieved in the patient group under study with the use of the described genioplasty technique in combination with mandibular setback by intraoral vertical ramus osteotomies.     

Sealing ability of a new polydimethylsiloxane-based root canal filling material

We tested the null hypothesis that there is no difference in the sealing ability of GuttaFlow, RoekoSeal, and AH26 in root canals. Sixty extracted mandibular premolars were filled with AH26 (lateral compaction), RoekoSeal, or GuttaFlow (modified single-cone). The sealing ability of the root canal fillings was measured weekly (4 weeks) by using a glucose penetration model. Kruskal-Wallis test revealed significant differences in glucose penetration between the experimental groups at weeks 1, 2, 3, and 4. Whereas GuttaFlow showed the highest amount of leakage at all times, AH26 showed the lowest. There was no significant difference between RoekoSeal-filled and AH26-filled root canals throughout the experimental period. AH26 showed better sealing ability in root canals than GuttaFlow.     

Root surface characteristics of children teeth with periodontal diseases

The present study examined the root surfaces of teeth from children with or without periodontal diseases and with or without systemic diseases. Light microscopy revealed that when compared to control teeth: teeth with chronic periodontitis had similar radicular histology; teeth from children with leukocyte adhesion deficiency, Down syndrome and aggressive periodontitis had narrower cementum areas; teeth from children with hypophosphatasia showed cementum aplasia. Cementum anomalies may facilitate the establishment and progress of periodontitis in children.     

Salivary procalcitonin and periodontitis in diabetes

Periodontitis and type 2 diabetes are co-morbid conditions, both characterized by infectious susceptibility. We investigated procalcitonin (ProCT) levels in the serum and saliva of persons with periodontitis and type 2 diabetes (n = 20), to determine if these levels are altered by periodontitis activity or by hyperglycemia. Persons with severe periodontitis showed higher levels of salivary-ProCT than did those with moderate periodontitis (241 +/- 71 vs. 77 +/- 516 pg/mL, p = 0.02) and higher levels than did healthy control individuals (118 +/- 26 pg/mL, p = 0.05). Salivary-ProCT levels were correlated with bleeding-on-probing (r = 0.45, p = 0.05), as well as with HgbA(1c) (r = 0.49, p = 0.03). Salivary levels of ProCT were higher than serum levels for the periodontitis/diabetes group (152 +/- 37 vs. 78 +/- 17 pg/mL, p = 0.02) and the control group (118 +/- 146 vs. 48 +/- 17 pg/mL, p = 0.01). Persons with periodontitis and type 2 diabetes have salivary-ProCT levels that reflect their degree of periodontitis activity and hyperglycemia. This study demonstrates, for the first time, the presence of procalcitonin (ProCT), an established serum marker of infection, in saliva.