Hans R. Preus

Oral administration of a new soluble branched β‐1,3‐D‐glucan is well tolerated and can lead to increased salivary concentrations of immunoglobulin A in healthy volunteers

The soluble branched yeast β‐1,3‐D‐glucan (SBG) belongs to a group of carbohydrate polymers known to exert potent immunomodulatory effects when administered to animals and humans. A new oral solution of SBG has been developed for local application to the oropharyngeal and oesophageal mucosa in order to strengthen the defence mechanisms against microbial and toxic influences. In the present study oral administration of SBG has been investigated primarily for assessment of safety and tolerability in an early phase human pharmacological study (phase I). Eighteen healthy volunteers were included among non‐smoking individuals. The study was an open 1 : 1 : 1 dose‐escalation safety study consisting of a screening visit, an administration period of 4 days and a follow‐up period. Groups of six individuals received SBG 100 mg/day, 200 mg/day or 400 mg/day, respectively, for 4 consecutive days. The dose increase was allowed after a careful review of the safety data of the lower dose group. No drug‐related adverse event, including abnormalities in vital signs, was observed. By inspection of the oral cavity only minor mucosal lesions not related to the study medication were seen in seven subjects. Repeated measurements of β‐glucan in serum revealed no systemic absorption of the agent following the oral doses of SBG. In saliva, the immunoglobulin A concentration increased significantly for the highest SBG dose employed. SBG was thus safe and well tolerated by healthy volunteers, when given orally once daily for 4 consecutive days at doses up to 400 mg.

Clinical and Microbiologic Effects of Adjunctive Antibiotics in Treatment of Localized Juvenile Periodontitis. A Controlled Clinical Trial

The aim of this study was to assess the clinical and microbiologic effects of the combination of amoxicillin and metronidazole therapy as an adjunct to mechanical treatment in the management of localized juvenile periodontitis. Twenty-five localized juvenile periodontitis (LJP) patients from a Brazilian population were randomly allocated into an experimental group receiving mechanical treatment and antibiotics, and a control group receiving mechanical treatment and placebo. Clinical and radiographic assessments, as well as microbiologic sampling for Actinobacillus actinomycetem.comitans, were performed at baseline and one year after the end of the treatment. At the termination of the study A. actinomycetemcomitans could be isolated from the oral cavity of all patients in the control group who harbored the bacterium at baseline and in 4 out of 8 patients in the experimental group. Both treatment modalities resulted in significant benefit on an individual basis. The experimental group, however, displayed better results than did the control group regarding gingival index (GI), probing depth (PD), clinical attachment level (CAL), and radiographic analysis of crestal alveolar bone mass, but not with respect to plaque index (PI). No serious adverse effects of the antibiotic treatment were observed in the present study. J Periodontol 1998;69:1355-1363.

Genetic diversity of Porphyromonas gingivalis and its possible importance to pathogenicity.

During recent years much effort has been put into understanding the genetic composition of the oral populations of black-pigmented anaerobic bacteria. One of them, Porphyromonas gingivalis, is a putative periodontopathogenic organism considered to be particularly relevant in the etiology of adult periodontitis. It has been shown in studies using molecular typing methods that most bacterial populations consist of numerous genetic clones, and that only a small proportion of these clones cause disease. Elucidation of a possible association of genotypic profiles with either disease or clinical healthy condition is important for understanding the pathogenic characteristics of bacteria. Studies addressing this issue as it relates to P. gingivalis are reviewed in the present article. Genotypic characterization of P. gingivalis strains has revealed extensive heterogeneity in natural populations of this bacterium. Some of the potential virulence factors of P. gingivalis have been purified and cloned and methods have been established to identify their genes. Although no studies have clearly defined the relationship between a specific genotype of P. gingivalis and periodontal status of the host, it seems that molecular typing tools, which are undergoing rapid improvements, will allow us to distinguish between virulent and avirulent strains of the same species in the near future.

Periodontitis in psoriasis patients. A blinded, case-controlled study

Abstract Objective. Destructive periodontitis is one of the most frequent and widespread bacterial infections in humans. Psoriasis is a common condition in the general population. Since both psoriasis and periodontal diseases are characterized by an exaggerated response of the immune system to the epithelial surface microbiota, there may possibly be an association between these two conditions. The aim of the present pilot study was to investigate the prevalence of periodontal disease in psoriasis patients compared to healthy controls. Material and methods. Dental bite-wing X-rays were obtained from 155 psoriasis patients aged 45–60 years, as well as from 155 age- and gender-matched controls. All X-rays were examined by the same investigator for accumulated destructive periodontitis using bone level and loss of teeth as endpoints. Results. A significantly lower radiographic bone level (p < 0.001) and a significantly higher number of missing teeth (p < 0.001) were observed in the psoriasis cases compared to the controls. Conclusion. Our study indicates that psoriasis patients experience more bone loss than age- and gender-matched controls.

Bacteriophage infection—a possible mechanism for increased virulence of bacteria associated with rapidly destructive periodontitis

We have recently isolated several groups of bacteriophages infecting Actinobacillus actinomycetemcomitans from periodontal lesions in patients with rapidly destructive periodontitis. Bacteriophage infection of these bacteria in these patients was restricted to periodontal pockets showing radiographic evidence of recent bone loss and suggests an association between phage-infected A. actinomycetemcomitans and active periodontal disease. On the basis of the biological activity of bacteriophages we propose a working hypothesis to explain the mechanism by which a phage may increase bacterial virulence in periodontal disease.

A Randomized, Double-Masked Clinical Trial Comparing Four Periodontitis Treatment Strategies: 1-Year Clinical Results

BACKGROUND The benefit of full-mouth disinfection (FDIS) over traditional scaling and root planing (SRP) remains equivocal, and it is not known whether the use of adjunctive antibiotics may enhance the effect of FDIS. The aim of the present study is to test the hypothesis that there is no difference in the 1-year clinical outcome of therapy among groups of patients treated with conventional SRP performed over 2 to 3 weeks, or same-day FDIS, with or without adjunctive metronidazole. METHODS A total of 184 patients with moderate-to-severe periodontitis were randomly allocated to one of four treatment groups: 1) FDIS+metronidazole; 2) FDIS+placebo; 3) SRP+metronidazole; or 4) SRP+placebo. Recordings of plaque, bleeding on probing, probing depth (PD), and clinical attachment level (CAL) were carried out in four sites per tooth at baseline and at 3 and 12 months after treatment. RESULTS No differences were observed in the mean CAL or PD values between the four experimental groups at baseline and 3 or 12 months post-treatment. All four groups displayed significant improvements in all parameters. However, using absence of pockets ≥5 mm as the criterion for treatment success, the two groups receiving adjunctive metronidazole performed significantly better than the two placebo groups. CONCLUSION Metronidazole had a significant, adjunctive effect in patients with a metronidazole-sensitive subgingival microbiota on the clinical parameters of CAL, PD, and absence of pockets ≥5 mm.

Influences of axial load and blood pressure on the position of the rabbit's incisor tooth

Changes in the axial position of the left upper incisor in response to loading by 5-20 g were measured with ultrasonic technique in anesthetized rabbits. The time-response of the load-induced intrusion described a biphasic curve, with a steep initial part followed by a slower part. Maximum amplitudes after 20 s increased with increasing loads. A rise in arterial blood pressure (aortic balloon inflation) resulted in extrusion, while i.v. injection of noradrenaline or papaverine caused intrusion and extrusion, respectively. The responses to loading and changes in blood pressure were largely unaffected by transection of the root, but the effects of pressure changes were severely diminished by local infiltration of the periodontium with noradrenaline. Participation of periodontal blood vessels in the damping of load-induced intrusion was excluded by the finding of roughly equal intrusion curves at low, normal and high blood pressure and up to 38 h after death. We conclude that the resting position of the rabbits incisor is greatly influenced by arterial blood pressure, via the periodontal vessels. The intrusion in response to loading by up to 20 g is resisted by periodontal fibers only, the blood vessels or the pulpal and periapical tissues and pressure taking no part.

Prevalence and severity of vestibular recession in mandibular incisors after orthodontic treatment

OBJECTIVE To assess the prevalence and severity of vestibular gingival recession of mandibular incisors after orthodontic treatment and to evaluate possible contributing factors. MATERIALS AND METHODS From the record pool of patients who completed orthodontic treatment from 1999-2006 at the Department of Orthodontics, University of Oslo, Norway, 588 patients fulfilled the inclusion criteria. Intraoral color slides were used for the evaluation of gingival recessions (based on Miller classification), presence of visible plaque, and gingival inflammation. Cephalometric radiographs were used to assess the sagittal intermaxillary relation, mandibular and intermaxillary angles, and the position of the lower incisors. A control group was drawn from the same pool of 588 patients. All statistical analyses were performed using SPSS. RESULTS The prevalence of gingival recessions after orthodontic treatment was 10.3%. Most (8.6%) were classified as Miller Class I, and 1.7% were classified as Miller Class II. Gingival recession was predominantly found on central incisors. Reduction of the sagittal intermaxillary angle and retroclination of the lower incisors was correlated with the development of a more severe gingival recession. CONCLUSIONS The present study indicates that vestibular gingival recession of mandibular incisors after orthodontic treatment is of minor prevalence and severity. The presence of gingival recession or retroclination of the incisors with mesial basal relations increases the risk of more severe gingival recession.

Microbiologic Observations After Four Treatment Strategies Among Patients With Periodontitis Maintaining a High Standard of Oral Hygiene: Secondary Analysis of a Randomized Controlled Clinical Trial

BACKGROUND The benefit of full-mouth disinfection (FDIS) over traditional scaling and root planing (SRP), with or without adjunctive metronidazole, when treating chronic destructive periodontitis remains equivocal, as does the long-term association between clinical and microbiologic outcomes after such strategies. The aim of this study is to examine the relationship between clinical and microbiologic outcomes of four different treatment strategies for chronic destructive periodontitis among patients who maintain excellent oral hygiene and low gingival bleeding scores. METHODS One hundred eighty-four patients with periodontitis and capable of maintaining a high standard of oral hygiene were randomly allocated to one of four treatment groups: 1) FDIS + metronidazole; 2) FDIS + placebo; 3) SRP + metronidazole; and 4) SRP + placebo. Recordings of plaque, bleeding on probing, probing depth (PD), and clinical attachment level were carried out in four sites per tooth at baseline, 3 and 12 months after treatment. Before treatment, pooled subgingival samples were obtained from the five deepest pockets, which were sampled again 3 and 12 months after treatment. Microbiologic assessments of eight putative periodontal pathogens were performed using the checkerboard DNA-DNA hybridization method. RESULTS Levels of bacterial species were already relatively low at baseline. The only microbial factor statistically significantly associated with the clinical outcomes of treatment after 12 months was the association between reductions of Tannerella forsythia and being free from PD ≥5 mm. CONCLUSION In this clinical trial, the only microbial factor associated with the clinical outcomes after 12 months was a statistically significant association between the reductions of T. forsythia and being free from PD ≥5 mm.

Invasive growth of Actinobacillus actinomycetemcomitans on solid medium (TSBV)

When grown on agar, most Actinobacillus actinomycetemcomitans form circular and convex colonies with an internal star-shaped morphology. Such colonies adhere firmly to the agar, and when removed, a star-shaped imprint similar to that of the intact colony remains. This study was undertaken to determine the nature of this in vitro growth. Stereo-microscopy and scanning and transmission electron microscopy showed that the star-shaped imprint of A. actinomycetemcomitans colonies reflected pseudopod-like extensions of the bacterial colony which penetrated deep into the TSBV agar. The center of the colonies consisted primarily of ghost-like cells, while the dense border of each colony, including the pseudopods, expressed characteristics of vital cells. The latter were embedded in vast amounts of extracellular vesicles, and the outer aspect of the pseudopods was lined with a border of such vesicles.