Mixed infection of Porphyromonas gingivalis and Bacteroides forsythus in a murine abscess model: involvement of gingipains in a synergistic effect

Several microorganisms including Porphyromonas gingivalis and Bacteroides forsythus have been implicated to be etiologically important agents of periodontal disease. In this study, we determined the ability of combinations of periodontopathogenic microorganisms to cause tissue destruction in a murine abscess model. Although all bacterial combinations used in this study produced larger abscesses than did monoinfection of each bacterium, the combination of P. gingivalis and B.forsythus showed a synergistic effect on abscess formation. Since these two bacteria have been frequently found together in lesions of periodontitis, these results suggest the significance of their co-infection in the progression of periodontitis. P. gingivalis produces extracellular and cell-associated cysteine proteinases (gingipains) which appear to be involved in its virulence. The rgpA rgpB double and kgp mutants induced significantly smaller abscesses than the wild type. Moreover, the rgpA rgpB kgp triple (gingipain-null) mutant hardly showed lesion formation at all with the experimental conditions used in this study, indicating that these genes encoding gingipains are important for virulence of P. gingivalis. Mixed infection of these P. gingivalis mutants with B. forsythus showed an additive effect on abscess formation, indicating that the gingipains of P. gingivalis may play an important role in the pathological synergism between P. gingivalis and B. forsythus.     

Effects of a nutritional supplement on periodontal status

Among the recommendations for the maintenance of gingival and periodontal health, few have focused on the value of nutritional supplements. The purpose of this study was to compare the effect of certain nutritional and plant-derived nutraceuticals and a placebo tablet in the reduction of gingivitis, bleeding, probing depths, and attachment levels in a 60-day two-cell, randomized, parallel clinical trial for patients with Type II periodontal disease. The vitamin therapy was introduced as an adjunct to patient homecare to determine if there was a quantifiable improvement to soft-tissue health and periodontal damage. Sixty-three patients were randomly divided into two groups of 32 and 31 subjects and given either a vitamin tablet containing seven active ingredients (experimental treatment) or a placebo tablet. The clinical parameters assessed were the gingival index (GI), bleeding index (BI), periodontal pocket depth (PD), and attachment levels (AL), and were recorded at baseline and 60 days. Patients took the assigned tablet at breakfast and at dinner after brushing their teeth twice daily. After 60 days, the data showed a clinical reduction in the GI, BI, and PD for the experimental group (P < .0001). There were no significant changes for AL with either the experimental or the placebo group. When the data were further analyzed for pocket depths of > or = 4 mm in patients receiving the experimental treatment, there were clinically significant improvements in the GI and PD from baseline to 60 days (P < .0001), but no significant differences in the BI and AL. There were no statistical differences in any of the indices when the data were compared between men and women. The results of the present study suggest that a multi-vitamin nutritional supplement might be a beneficial adjunct to the required established periodontal treatment.     

Chemo-mechanical caries removal: a review of the techniques and latest developments

Chemo-mechanical caries removal involves the chemical softening of carious dentine followed by its removal by gentle excavation. The reagent involved is generated by mixing amino acids with sodium hypochlorite; N-monochloroamino acids are formed which selectively degrade demineralised collagen in carious dentine. The procedure requires 5-15 minutes but avoids the painful removal of sound dentine thereby reducing the need for local anaesthesia. It is well suited to the treatment of deciduous teeth, dental phobics and medically compromised patients. The dentine surface formed is highly irregular and well suited to bonding with composite resin or glass ionomer. When complete caries removal is achieved, the dentine remaining is sound and properly mineralised. The system was originally marketed in the USA in the 1980's as Caridex. Large volumes of solution and a special applicator system were required. A new system, Carisolv, has recently been launched on to the market. This comes as a gel, requires volumes of 0.2-1.0 ml and is accompanied by specially designed instruments.     

Exposure of high-density porous polyethylene (Medpor) used for contour restoration and treatment

Porous high-density polyethylene (Medpor) is a biocompatible large-pore, high-density polyethylene implant. It is well tolerated by surrounding tissue, and its porous structure is rapidly infiltrated by host tissue. It is a highly stable and somewhat flexible porous alloplast that has rapid tissue ingrowth into its pores. However, when the implant is placed under a thin cover of skin, there is a risk of exposure. A total of 52 Medpor implants were placed in 31 patients over a four-year period. The implants were used for the chin, malar area, nasal reconstruction, ear reconstruction, orbital reconstruction, and the correction of mandibular contour deformities. Many of these implants were placed in areas considered problematic, such as those with thin or atrophic soft-tissue coverage and extensive scarring. There were nine complications, including three patients in whom the implant was exposed; these are presented here.     

Long-standing intranasal foreign body: an incidental finding on dental radiograph: a case report and literature review

A case of an incidental finding of an intranasal foreign body on a dental panoramic radiograph is reported. The foreign body, a calculus-encrusted plastic pearl, had been asymptomatic despite being present for over 20 years. The diagnosis of a nasal foreign body in a patient is of significance if an oral surgical procedure is being planned with the patient under general anesthesia because the foreign body may be dislodged into the airway during nasal intubation. Similar reports of incidentally discovered intranasal foreign bodies on dental radiographs are reviewed. The epidemiology, diagnosis, management, and complications of nasal foreign bodies are discussed.     

Fatigue behavior of the zinc-phosphate cement layer

PURPOSE: Fatigue behavior of luting cement film between model fixed partial dentures (FPD) and their dies was investigated to gain a better understanding of the mechanical properties of zinc-phosphate cement. MATERIALS AND METHODS: Fifty-six brass dies were made, half of them with grooves and half without grooves. A cantilever FPD for each die was cast in Au-Pd-Ag alloy. Four linear strain gauges were attached to the marginal portions of each retainer. The FPDs were cemented to the dies using zinc-phosphate cement. A fatigue test machine was used to cyclically load the specimens with 50 or 100 N for 5.5 x 10(5) cycles (1 Hz) in 37 degrees C water. During the fatigue test, strain measurements were made after every 0.5 x 10(5) load cycles to discover if strain response was altered. After completion of the fatigue test, ultimate tensile strength of each specimen was measured and statistically analyzed by 2-way analysis of variance. RESULTS: With or without grooves, strain responses were the same at every periodic strain measurement throughout the 50-N fatigue test. For the 100-N fatigue test, strain responses for the specimens without grooves were different before and after cyclic testing, but there was no difference for the specimens with grooves. There were no significant differences in tensile strength among the specimens after the fatigue tests. CONCLUSION: No fatigue fracture was observed in zinc-phosphate cement film after repetitive loading. Repetitive loading may improve stress transmission within the zinc-phosphate cement film.     

Effect of supragingival plaque control on subgingival microflora and gingivo-periodontal tissues

The aim of this study was to carry out a short term evaluation of the effect of supragingival plaque control on the subgingival microflora and gingivoperiodontal tissues in patients with moderate and severe periodontitis. A total of 92 sites from 23 patients were studied; patients ranged between 35 and 60 years of age (x 46.4 +/- 1.71). Plaque Index (PI), Gingival Index (GI), Bleeding on Probing (BP), Probing Depth (PD), and Attachment Level (AL) were measured. Subgingival microflora of the same sites was studied by dark field microscopy, and cultures in non-selective and selective media for Actinobacillus actinomycetemcomitans (Aa), Prevotella intermedia/nigrescens (Pi/n), Porphyromonas gingivalis (Pg) and Fusobacterium nucleatum (Fn). The patients were included in a supragingival plaque control program which included oral hygiene training and assessment, and professional control of supragingival plaque and calculus. After 28 days, measurement of clinical parameters and the microbiological study were repeated. The sites were divided according to baseline PD values into: Group 1 (5 mm), Group 2 (6 mm) and Group 3 (> or = 7 mm). Results revealed a significant reduction in PI scores, GI scores, PB and PD in groups 2 and 3. No significant difference in AL was observed in any of the three groups. PI scores were found to decrease significantly in group 1, and GI scores, BP and PD tended to decrease. A significant increase in coccoid cells and a significant decrease in motile rods and spirochetes, both small and total, was observed in groups 2 and 3. Group 1 showed a significant decrease in medium and total spirochetes. At the end of the study, a significant decrease in Pi/n was found in all three groups. Significant decreases were found in Pg and Fn in Groups 3 and 2 respectively. Although it holds true that supragingival plaque control reduced a potentially pathogenic subgingival microbiota, this effect was not sufficient to be compatible with healthy gingivoperiodontal tissues.     

Oral lichen planus, amalgam and other restorative materials

Mucosal lesions in the oral cavity, identical to oral lichen planus (OLP), as a consequence of contact with in particular dental silver amalgam may be due to an allergic reaction to mercury or, possibly, a toxic effect on the oral mucosa. Substitution of amalgam preferably by gold--unless sensitisation to gold exists--often results in remission, which sustains a pathogenic role of amalgam in OLP. Substitution of amalgam should be considered if the mucosal lesions correspond topographically to the restorations and epicutaneous patch testing results in a positive reaction on mercury.