Biomedical subjects
Publications and source records attributed to T J Bloem.
The concept and use of spark erosion (EDM) prosthetics in implant prosthodontics has been described and demonstrated in its application to a patient suffering maxillofacial trauma. The advantages and disadvantages of this technology have been discussed for the edification of the restorative and surgical provider.
This study assessed the colonization of Brånemark dental implants by periodontopathic bacteria in four partially edentulous patients with a total of 10 implants. Marginal and subgingival plaque on the implants was sampled 14 days and 28 days after second-stage surgery and compared with plaque from three teeth closest to the implant sites sampled before second-stage surgery (baseline) and at 14 and 28 days. Slot immunoblot assay was used to determine the presence or absence of bacterial antigen to six different periodontopathic microorganisms. In general, colonization of marginal implant plaque occurred within 14 days, whereas subgingival colonization took longer and occurred within 28 days. It appears that Brånemark dental implants placed in partially edentulous patients may be colonized by disease-associated bacteria within 14 days of second-stage surgery.
This in vitro pilot project compared the effect of two air-abrasive prophylaxis systems on the surface of machined titanium. Single Brånemark titanium abutment cylinders were exposed to the Prophy-Jet and Microprophy systems for 90 seconds each. Both of the test cylinders were compared with an untreated control cylinder by scanning electron microscopy. Machining marks were completely removed by the Prophy-Jet and only partially removed by the Microprophy. Both of the resultant surfaces appeared to be smoother and thus may be more resistant to plaque formation. A rationale for the removal of machining marks is presented, although the reason for the difference in removal by the two systems is unclear. The prophylaxis cleaning powders were also examined by scanning electron microscopy and exhibited similar particle dimensions and morphology. A noncrystalline deposit was observed on the surface of the abutment cylinder exposed to the Microprophy. Energy dispersive spectroscopy analysis revealed that the deposit consisted almost entirely of sodium. Further investigation of the deposit is needed.
PURPOSE: The in vivo wear resistance of 12 composite resins were compared with an amalgam control using the Latin Square experimental design. Sixteen edentulous patients wearing specially designed complete dentures formed the experimental population. MATERIALS AND METHODS: The Michigan Computer Graphics Measurement System was used to digitize the surface of the control and composite resin samples before and after 3-month test periods to obtain wear data. The 12 composite resins selected for this investigation based on their published composite classification types were seven fine particle composites, three blends, and two microfilled composite resins. The Latin Square experimental design was found to be valid with the factor of material being statistically different at the 5% level of significance. Wear was computed as volume loss (mm3/mm2), and all of the composites studied had more wear than the amalgam control (P = .001). RESULTS: After 3 months, the mean (error) of wear of the amalgam was 0.028 (0.006). Means (error) of wear for the 12 composites were ranked from most to least wear by mean wear volume loss. CONCLUSION: The absence of any relationship between mean wear volume loss and the volume percentage filler was confirmed by the correlation coefficient r = -0.158.
This article reports the findings of two interrelated projects that measured the accuracy of electroplated, epoxy resin, and polyurethane die materials against a master tooth, using the Michigan Computer Graphics Coordinate Measuring System (MCGCMS). In the first phase, on occlusal die morphology, replications of a master tooth were used to validate the MCGCMS reliability. Eighteen total data sets derived from three silver-plated dies and three epoxy resin dies were then compared with a representative data set of the master tooth. The mean differences for all silver-plated die and epoxy die measurements against the master ranged from -42 to -49 and -46 to -230 microns/mm2, respectively. In the second phase, two epoxy die materials and a polyurethane system were compared with a master tooth in an identical manner. In paired comparisons to the master tooth, mean differences for Epoxydent material, epoxy resin, and polyurethane dies ranged from -147 to -153, -149 to -230, and -56 to -168 microns/mm2, respectively. A Student t test using a CLR ANOVA was performed between the master tooth and the five die systems. A significant difference was revealed between the enamel-silver difference and the enamel-Epoxydent difference data at the 95% confidence level. A significant difference also occurred between enamel-silver and enamel-epoxy resin. It was concluded that silver-plated dies are acceptable replicas of a master tooth. Epoxydent and epoxy resin dies did not provide reliable replications when compared with the silver-plated dies. Epoxy and polyurethane replications, although reported as accurate, were inconclusive.
The accuracy of master casts fabricated from three impression techniques commonly used with the Brånemark System was measured. Points placed in a metal surrogate model and onto master abutments were compared after abutments were transferred to stone casts using splinted and unsplinted impression coping techniques. The mean values and standard deviations of each of the reference points on 12 total casts were compared with the values for each point from the surrogate model. Values from techniques using splinted and unsplinted squared polymer copings as well as unsplinted tapered hydrocolloid copings were not significantly different from values recorded from the master surrogate model. Tapered hydrocolloid copings yielded a higher correlation to coordinate values on the master than unsplinted squared polymer copings or splinted squared copings.
Prosthodontic management of patients with implants of any kind will logically begin from the time at which the patient first presents for examination. It is essential that the patient be managed by an effective team. The restorative dentist, responsible for the ultimate restoration of the patient, should be a leading member of the implant team. The prosthodontist assumes ultimate responsibility for determination of fixture number and location based on prosthetic and functional needs. By carefully evaluating conditions with the other team members, the limitations and potential for fixture placement will be realized and consensus regarding treatment objectives will be achieved. This paper provides an overview of the restorative dentist's role in general patient assessment, in surgical and restorative treatment planning, and in the various stages of treatment from surgical placement through a range of definitive reconstructive procedures.
Future development in implant prosthodontics should be based on the fundamentals of sound research and reliable clinical implementation. The goals should be to research the safety and efficacy of implants with regard to materials, host receptor site and interfacial zone; to develop acceptable uniform standards of evaluation; and to submit findings to scientific methods of analysis in determining benefit-to-risk factors. This presentation will offer a glimpse at some current developments in basic and clinical research focusing on studies in biocompatability and host acceptance; the implant-tissue interface; processes in osteogenesis related to vascularization of host sites; and bioengineering studies related to stress analysis and dimensional accuracy of impression systems for implants. The presentation will further describe future direction in research, training and implementation of services through development of an interdisciplinary team. A center is proposed to address the need for combined efforts in clinical and basic science research, the broad scope of implant utilization, and the teaching of implant procedures within an academic setting and to our colleagues.
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Three-dimensional coordinate measuring machines for examining the quality of industrial castings were reviewed. The concept was modified and successfully converted to examine the minute geometric configurations of the surfaces of dental materials. The wear of composites has undoubtedly precipitated this perceptive, thorough study.
A review of literature relating to velopharyngeal dysfunction reveals that there is no consensus regarding the precise definition of the terms "velopharyngeal incompetence," "velopharyngeal inadequacy," or "velopharyngeal insufficiency." Since this represents an obstacle to communication among members of multidisciplinary teams concerned with rehabilitation of velopharyngeal problems, current usage of these terms is reviewed and recommendations for clarification of the nomenclature are provided.
The relationship between denture base plaque and mucosal inflammation under complete dentures was tested by clinical comparison with the PTI and a comparable plaque-scoring technique. Two treatment groups, one of which practiced tissue-brushing only and the other denture-brushing only, were compared with a control group with regard to mucosal inflammation and denture plaque score. Significant reduction in inflammation occurred, although no reduction in denture base plaque score was found. The effect of denture plaque on denture stomatitis and the efficacy of denture-brushing as a plaque removal technique is challenged.
The effect of lidoflazine administration (120 mg t.i.d. for 9 weeks) on work tolerance (bicycle ergometer), frequency of anginal attacks, and nitroglycerin consumption was investigated in 28 male patients with stable angina pectoris in a combined single-blind/double-bline study. Lidoflazine increased work tolerance and reduced the frequency of anginal attacks and nitroglycerin consumption. The higher work tolerance level was reached at maximal heart rate and heart rate--systolic blood pressure product values similar to those before treatment. The values of these variables after 3 min of exercise at 60 W, however, were significantly lower after treatment with lidoflazine. These findings indicate that the heart is performing more economically during lidoflazine treatment. The improved work tolerance can probably be ascribed to lidoflazine and not to a training effect because of the significant reduction of this variable in the patients allocated to placebo as compared to those remaining on lidoflazine treatment. The side effects were generally slight. In one patient the prolongation of the QT interval due to lidoflazine resulted in rhythm disturbances.
Pindolol was given for 12-15 consecutive weeks to 35 patients for the treatment of essential hypertension. Significant blood pressure reductions were achieved in the group of 28 patients who completed the trial, as tested by the Wilcoxon pair test. There was no difference in antihypertensive effect between a three times a day and a twice a day administration schedule. The incidence of side-effects was not affected by the change in dosage or schedule.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
The Michigan Computer Graphics Coordinate Measurement System was used to measure the wear of three composite resins and an amalgam alloy control. The validity of the Latin Square experimental design for analysis in a clinical study was demonstrated, and statistically significant differences in wear were established for main effect for the materials under investigation. None of the composite resins examined approximated the amalgam alloy control in wear properties. Rank ordering of the materials with respect to wear was possible using this experimental design. Ranking of the materials for wear resistance using this research approach opens up other future research opportunities to correlate such properties as filler particle size, composition, and distribution with the data derived.