Gated cardiac magnetic resonance structural imaging: optimization by electronic axial rotation

Most magnetic resonance imaging has used body orthogonal axes with the Z axis placed along the length of the body and the X and Y axes at right angles to the body. This orientation is not optimum for the heart; visualization of sections along the short and long cardiac axes would best define cardiac structural detail and functional status. The new orientation was accomplished by selection of electronic angulation of the magnetic fields for each subject rather than by attempting to approximate the cardiac axes by altering the position of the patient. This technique improved visualization of comparative wall segments, valvular structures, and the true four-chamber view of the heart, and also gave the best visualization of the pericardium. In addition, more accurate estimates of chamber size and myocardial mass can be made from the short-axis orientation, since the sections are orthogonal to the myocardium.     

Safety and efficiency of novel sonic scaler tips in vitro

BACKGROUND: The aim of the study was to evaluate a novel sonic scaler tip for subgingival root surface instrumentation combining high efficiency in calculus removal with minimized risk of root damage through subgingival debridement. METHODS: A metal sonic scaler tip with a paddle-like working end covered with spheroid convexities of 0.8 mm diameter and 0.3 mm height was designed from the aspect of optimized adaptation to the root anatomy (tip-end dimension: 3.0 x 1.5 x 0.6 mm). Using a customary sonic scaler tip as control, instrument efficiency was quantified by measuring the time needed to completely remove calculus on extracted teeth (n=52) under standardized conditions. To quantify the amount of calculus removed, the mean calculus area per tooth was measured on photographs taken before instrumentation. The tips safety was evaluated instrumenting calculus-free root surfaces in vitro (n=18, lateral forces 0.5, 1, 2 N, 20 s instrumentation time, tip angulation 0 degrees ) with subsequent laser-optical determination of resulting root substance loss. RESULTS: Debridement efficiency was significantly higher for the novel tip (0.78+/-0.81 mm2/s completely debrided) than for the conventional tip (0.42+/-0.33 mm2) (Mann-Whitney test, p<0.05). Concerning instrument safety, the novel tip caused significantly less root substance loss than the conventional tip. CONCLUSION: The novel scaler tip appears to be significantly more efficient in calculus removal and less damaging to the root surface than the assessed conventional tip.     

Prevalence of Porphyromonas gingivalis fimA genotypes in Caucasians

The aim of the present study was to determine the prevalence of Porphyromonas gingivalis fimA genotypes in Caucasian patients with periodontitis. A total of 102 patients harboring P. gingivalis subgingivally were enrolled into the study. Pooled subgingival plaque samples of the six most severely affected sites were taken and analysed by fimA-specific polymerase chain reaction (PCR) and restriction analysis. Moreover, 26 P. gingivalis isolates were analysed by sequence analysis of the fimA gene. Sequence analysis revealed five major fimA genotypes (fimA types I-V) and allowed further subtyping of fimA genotypes II and IV into two subgroups each. The overall prevalences of fimA genotypes as assessed by PCR and restriction analysis among the P. gingivalis-positive patients with periodontitis were: type I, 25.5%; type II, 38.2%; type III, 4.9%; type IV, 18.6%; type V, 3.9%; and non-typable, 6.9%. Two patients were colonized by both type II and type IV, or type III and type IV fimA genotypes, respectively. Patients harboring different fimA genotypes showed no significant difference in severity of periodontal disease, as assessed by pocket probing depth and bleeding on probing following adjustment for smoking habit and age. The results indicate that predominant fimA genotypes in Caucasian periodontitis patients are types I, II, and IV. However, there was no difference in the association of the various fimA genotypes with disease severity.     

Adjunctive antimicrobial therapy of periodontitis: long-term effects on disease progression and oral colonization

BACKGROUND: This study assessed the long-term effects of adjunctive antimicrobial therapy on periodontal disease progression and oral colonization. METHODS: Patients with previously untreated chronic periodontitis and subgingival Actinobacillus actinomycetemcomitans and/or Porphyromonas gingivalis were randomly assigned to subgingival scaling without (control group) or with systemic amoxicillin plus metronidazole and CHX irrigation (test group). Relative attachment levels were determined and subgingival and mucosal plaque samples were taken at baseline, at 10 days (plaque only) and at 3, 6, 9, 12, 18, and 24 months following initial therapy. During maintenance therapy, patients received supragingival debridement only. RESULTS: After 24 months, the 18 test group patients showed at sites with initial probing depths (PD) > or =7 mm a significantly (P <0.05) higher frequency of 2 mm or more attachment gain (37.3% +/- 4.6%) and lower frequency of attachment loss (7.2% +/- 3.1%) compared to the 17 controls (8.2% +/- 3.9% and 19.1% +/- 13.1%, respectively). Compared to controls, the intraoral prevalence of A. actinomycetemcomitans (up to 18 months) and P. gingivalis (up to 3 months) decreased and that of Eikenella corrodens (at 10 days) increased in test patients (P <0.05). In both treatment groups, the detection frequency of Tannerella forsythensis decreased transiently, while an overall increase was recorded for Treponema ssp. CONCLUSIONS: Over the 24-month period, a single course of the administered adjunctive antimicrobial therapy led to a relative risk reduction of 62% for attachment loss at deep sites. However, with the exception of A. actinomycetemcomitans, it failed to induce long-term changes in the prevalence profiles of oral colonization.     

Root defects following air polishing

AIM: Air-polishing devices (APDs) are highly effective in removing plaque and extrinsic staining. Their application on root surfaces, however, may result in clinically relevant substance removal, limiting the use in patients with periodontitis, where denuded root surfaces are frequently found. Therefore, the purpose of the study was to assess the influence of different working parameters on root damage and to identify those minimizing root damage. MATERIAL AND METHODS: Defect depth and defect volume after instrumentation of roots with an APD (Dentsply Prophy-Jet) using conventional NaHCO3 powder at instrumentation times of 5, 10 and 20 s, combinations of low, medium and high powder and water settings, distances of 2, 4 and 6 mm, and angulations of 45 degrees and 90 degrees were quantified laseroptically. A total of 297 roots were instrumented and parameter combinations were performed in triplicate. The influence of each working parameter on substance loss was determined by multiple regression analysis. RESULTS: Time had the greatest influence on defect volume and depth (beta-weights 0.6 and 0.57, respectively), when compared with powder setting (beta-weights 0.49 and 0.3) and water setting (beta-weights 0.28 and 0.3). Variations in distance affected defect depth (beta-weight 0.44), but not volume (beta-weight 0.04). No major differences were found at 45 degrees and 90 degrees. Various parameter combinations led to maximal defect depths of 473.5 +/- 26.2 micro m within 20 s. CONCLUSION: Root damage varies among combinations of working parameters. Using the APD with the assessed NaHCO3 powder, all parameter combinations led to substantial root damage. Thus, APDs using NaHCO3 may not be safely utilized on exposed root surfaces.