Determination of Intensity-Based Stochastic Models for Terrestrial Laser Scanners Utilising 3D-Point Clouds.

Recent advances in stochastic modelling of reflectorless rangefinders revealed an inherent relationship among raw intensity values and the corresponding precision of observed distances. In order to derive the stochastic properties of a terrestrial laser scanner’s (TLS) rangefinder, distances have to be observed repeatedly. For this, the TLS of interest has to be operated in the so-called 1D-mode—a functionality which is offered only by a few manufacturers due to laser safety regulations. The article at hand proposes two methodologies to compute intensity-based stochastic models based on capturing geometric primitives in form of planar shapes utilising 3D-point clouds. At first the procedures are applied to a phase-based Zoller + Fröhlich IMAGER 5006h. The generated results are then evaluated by comparing the outcome to the parameters of a stochastic model which has been derived by means of measurements captured in 1D-mode. Another open research question is if intensity-based stochastic models are applicable for other rangefinder types. Therefore, one of the suggested procedures is applied to a Riegl VZ-400i impulse scanner, as well as a Leica ScanStation P40 TLS that deploys a hybrid rangefinder technology. The generated results successfully demonstrate alternative methods for the computation of intensity-based stochastic models as well as their transferability to other rangefinder technologies.

Microbiota of exposed root surfaces after fluoride, chlorhexidine, and periodontal maintenance therapy: a 3-year evaluation.

BACKGROUND: Fluoride and chlorhexidine (CHX) are state-of-the-art preventive measures for remineralizing teeth and for preventing plaque accumulation. The aim of this study was to examine the effects of fluoride and CHX varnishes on root caries and microbiota located on root surfaces. METHODS: Thirty-three patients from a periodontal maintenance program, having at least one tooth with gingival recession in each quadrant, participated in this study. One tooth per quadrant was assigned randomly to the control group or to one of the test groups that were treated with fluoride varnish, 1% CHX, or 40% CHX. The varnish treatment and the tooth cleaning were repeated every 3 months. Clinical examinations were performed at baseline and once a year for 3 years. Caries status and oral hygiene indices were evaluated clinically. The total cultivable microbiota and percentage of Mutans streptococci (MS), Actinomyces (ACC), and lactobacilli (LB) were analyzed. RESULTS: Oral hygiene was improved greatly during the course of the study. The percentage of MS, ACC, and LB of the total cultivable microbiota revealed a statistically significant reduction between baseline and final examination for each of the four groups. CONCLUSION: Professional tooth cleaning alone at 3-month intervals might be as effective in reducing MS, ACC, and LB as adjunctive treatment with fluoride or chlorhexidine.

Replacement of the aortic valve in patients under 50 years of age: long-term follow-up of the St. Jude Medical prosthesis.

BACKGROUND: Aortic valve replacement in the young adult (aged 18 to 50 years) is a choice between a mechanical prosthesis with attendant lifelong anticoagulation or biological prostheses of varying types that may have limited life expectancy in this age group. METHODS: The Cardiac Surgical Research Foundation database was accessed to determine long-term outcomes in patients having aortic valve replacement with the St. Jude Medical Valve. This database has been privately maintained since the world's first St. Jude Medical (SJM) valve implant in 1977. Patients were contacted by questionnaire or by telephone if the survey was not returned. Follow-up was 93% complete. RESULTS: From October 1977 through October 1997, 271 patients less than 50 years of age had isolated aortic valve replacement. Follow-up was 1957 patient years. Thirty-day operative mortality was 1.1% with 18 late deaths, 4 of which were valve related. Ninety percent of survivor INR responses indicated a frequency of monthly INR checks or less. Valve-related events including percent per patient year and mortality related to these events included thromboembolism, 6 episodes (0.3% per patient year, no deaths); anticoagulant-related bleeding, 6 events (0.3% per patient year, 2 deaths); paravalvular leak, 6 events (0.3% per patient year, 2 deaths); valve thrombosis, 2 events (0.1% per patient year, no deaths); and endocarditis, 3 events (0.15% per patient year, no deaths). There was no incidence of structural valve failure. CONCLUSIONS: The SJM valve has a long record of excellent performance with durability lasting more than 20 years. The incidence of untoward events is low and death over time due to valve-related complications is low (4 of 271). The SJM valve has become our valve of choice for younger patients.

Decision-making in the choice of heart valve for replacement in patients aged 60-70 years: twenty-year follow up of the St. Jude Medical aortic valve prosthesis.

BACKGROUND AND AIM OF THE STUDY: The choice of a cardiac valve for patients with aortic valvular pathology remains controversial. Younger patients may be at risk for long-term complications from chronic anticoagulation yet require prosthesis longevity, while older patients may not outlive a bioprosthesis. To gather information to help decision-making, the 20-year experience of aortic valve replacement (AVR) with the St. Jude Medical (SJM) valve by the surgeons of Cardiac Surgical Associates, P.A., was reviewed. METHODS: Cardiac Surgical Associates Research Foundation maintains a database of all patients undergoing valve replacement with the SJM aortic prosthesis since the world's first implant in October 1977. Patient follow up is conducted by questionnaire and/or telephone interview. The 20-year follow up period ended in October 1997. Follow up is 96.3% complete, and extends to 13,208 patient-years. RESULTS: A total of 2,390 aortic valves (1,500 in males, 890 in females) were replaced in the period studied. Among these patients, 1,419 had isolated AVR, whilst the remainder had AVR plus coronary artery bypass (CAB) or other procedures. The mean age was 63 +/- 14 years for AVR, and 70 +/- 10 years for AVR/CAB. Over the 20-year follow up period, freedom from valve-related events for the entire group was: thromboembolism, 97%; anticoagulant-related hemorrhage, 94%; valve thrombosis, 99.7%; prosthetic valve endocarditis, 99.2%; and paravalvular leak, 99.6%. Freedom from structural failure was 100%. Mortality for these events was low (15 deaths among 250 events; 6%). Overall survival at 5, 10, 15 and 19 years was 82, 66, 51 and 45% respectively for isolated AVR, and 72, 45, 25 and 15% respectively for AVR/CAB. CONCLUSION: The SJM valve has excellent hemodynamics and a low incidence of valve-related complications. Improvements in anticoagulation monitoring with the newly introduced and funded home monitoring program, as well as the introduction of newer and more effective antiplatelet drugs, will improve the safety of patients requiring chronic anticoagulation. With durability unquestioned, these long-term data show the SJM valve to be an excellent choice for AVR in patients aged 60-70 years.