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Biomedical subjects

L Borchers

Publications and source records attributed to L Borchers.

15 recordsLinked to original sources
PubMed2004

Elongated styloid process: when is it really elongated?

OBJECTIVE: The styloid process (SP) is often denoted as elongated when it is longer than 30 mm or 33 mm. These dimensions, based on early reports, do not respect the natural variation of the SP. The aim of this study is to investigate the natural variation of the length of the SP. Knowing this variation is a prerequisite for consistent terminology in anatomy and anthropology; it is essential for the classification of the SP as elongated on panoramic radiographs (PRs). MATERIALS AND METHODS: 1000 consecutive PRs of a normal population were retrieved from inactive files at the Dental School of the Hannover Medical University. Measurements of the length of the SPs were made directly on the radiographs from the caudal margin of the tympanic plate to the tip of the SP. RESULTS: On 521 of the 1000 PRs the length of the SP could be measured at least on one side. As there was no significant difference between distributions on the left and right side, both sides were combined to give a total of 837 measurements. The median was 28.0 mm, the interquartile range was from 23.0 mm to 36.0 mm. The distribution depends significantly on age and gender. The 90th percentile varies between 42 mm for women under 35 years and 49 mm for men aged over 35 years. CONCLUSIONS: The medians in our sample correspond to the thresholds for elongated SP quoted in the literature. Our results show that these thresholds are too low, since they are exceeded in 50% of normal patients. We propose that the SP should be considered to be elongated only if its length exceeds 45 mm, which corresponds to the average of the 90th percentiles for different sex and age groups.

Adult↗
PubMed2001

[Styloid process: radiograph and craniomandibular dysfunction (CMD)].

The aim of the study was to investigate the suitability of orthopantomograms for measuring the length of the styloid process (SP), and to determine the frequency of elongated SP in patients with craniomandibular dysfunction (CMD). For 350 patients, two ortho-pantomograms were available, produced by a SIEMENS Orthophos 5 using programs P1 and P6, respectively, plus a craniomandibular function index. The SP length measurements from the orthopantomograms and the palpation findings were correlated. In 34,7% of the 700 orthopantomograms the SP was measurable. The mean length was determined to be 29.1 mm in OPT1 films on both sides. In the OPT6 films the length values were 30.1 mm on the right, and 30.4 mm on the left side. In CMD patients there was no evidence of the SP causing the complaints. Two conclusions can be made: For epidemiologic studies on the length of the styloid process, the orthopantomogram is of limited use. In CMD patients the elongated styloid process is of negligible importance as a cause of complaints.

Adolescent↗
PubMed1999

Surface quality achieved by polishing and by varnishing of temporary crown and fixed partial denture resins.

STATEMENT OF PROBLEM: Studies have suggested that coating a temporary restoration with varnish material could replace time-consuming polishing procedures needed for achieving an optimally smooth surface. PURPOSE: This study examined the surface roughness of acrylic resins after having been polished or coated with different varnish materials. MATERIAL AND METHODS: A total of 360 cylindrical specimens were fabricated from 9 brands of resin. One surface on each specimen was machined flat and subsequently either polished with rubber polishers or coated with 1 of 9 varnishes. Selected specimens were subjected to thermal cycling (5 degrees C to 55 degrees C, 2000 cycles). Surface quality was assessed by means of a profilometer and by SEM examination. RESULTS: Polished specimens had average surface roughness values (Ra) of 0.8 microm; differences in roughness between materials were small, but statistically significant. Type of coating had a significant influence on surface quality. Depending on the combination of materials used, the coating produced both smoother and rougher surfaces than polishing (0.4 microm < Ra < 4.6 microm). Five coatings were deemed not to be clinically applicable because of poor wetting properties. Thermal cycling did not significantly influence surface quality, but caused minute cracks in the cyanoacrylate coating. CONCLUSION: In regard to surface quality and applicability, the use of varnishes on temporary restorations is not advisable.

Acrylic Resins↗
PubMed1999

An experience in telenursing.

The purpose of this article is to describe how a telemedicine system was used to complete a family and home assessment and to discuss issues facing advanced practice nurses (APNs) when they use such systems in practice. Incorporating discharge care into advanced practice is an increasingly important component of the nursing care given during acute illness. Telemedicine systems offer a mechanism for assessing the ways in which home situations impact on patient recovery. Telemedicine provides a method for early intervention that can ameliorate or prevent developing problems relatively inexpensively. The advantages and disadvantages of one such system, the Picasso, are described.

Community Health Nursing↗
PubMed1998

Reducing readmission rates through discharge interventions.

Readmissions to the hospital account for a significant number of all hospital admissions. Early discharge and inadequate care both during and after hospitalization are among the causes cited. Increasingly complex care and an aging population mandate that clinical nurse specialists (CNSs) in acute care settings assume more pivotal roles in discharge planning and care. Discharge program and intervention models, and ways to incorporate discharge interventions into advanced practice in acute care hospitals, are discussed. In addition, the effectiveness of CNSs and their required qualifications are presented.

Acute Disease↗
PubMed1995

Measurement of tooth displacements and mouthpiece forces during brass instrument playing.

In order to assess the actual load on front teeth and tooth supportive tissue during brass instrument playing, a measuring system was developed permitting simultaneous recordings of mouthpiece forces and incisor deflections. By the application of strain gauges, the mouthpiece itself was converted into an extra-oral force transducer, whilst an intra-oral metal appliance similar to a removable partial denture served as the base for strain gauge transducers sensing incisor displacements. The measurements only slightly affected the handling of the instruments under examination (trumpet, french horn, tenor horn, and tuba) and yielded the following average results for three to five players per instrument: peak force values were in the range of 29 N (tuba) to 50 N (trumpet), and the respective peak displacements were 43 microns and 100 microns.

Biomechanical Phenomena↗
PubMed1990

[Measuring the accuracy of various elastomeric impression materials using a CNC coordinate measuring device (Part 1)].

This study compares the accuracy of 23 impression materials. With each material seven impressions of a stainless steel master die were taken under standardized conditions. Characteristical dimensions of the master die and of the stone dies as well were determined by means of a CNC coordinate measuring device. Differences in prepared tooth heights ranged between -36 and +19 microns. The occlusal distances between prepared teeth were 2 to 54 microns greater on the stone dies than on the master die. Diameters differed by -89 to +52 microns. The two phase impressions tended to result in stone dies of reduced size, whereas single phase and double mix impression techniques produced larger stone dies than the master die.

Dental Impression Materials↗
PubMed1989

[Creep of amalgam fillings under clasp rests].

A clinically realistic experiment was set up to obtain information on the amount of vertical settling of clasp rests in amalgam restorations under functional loading. Mesioocclusal cavities were prepared in 16 lower molar specimens cast in brass. The cavities were filled with amalgam and provided with a mesial rest seat. A constant load of 100 N was applied via a simplified (experimental) saddle to a cobalt-chromium E-clasp cast to the saddle. The duration of the load corresponded to 160 days of clinical function. The chronological course of vertical displacement was analyzed mathematically. According to this result the process can be divided into three components: settling immediately upon load initiation (mean value 96 microns, transition creep (mean value 25 microns) and creep ata constant rate (mean value 15 microns). The mean overall vertical displacement of the rests was 136 microns, the maximum value 287 microns. These findings suggest that vertical settling of a clasp rest into its seat in an amalgam restoration may eventually result in significant changes in occlusion and may almost completely exhaust gingival resilience.

Dental Amalgam↗
PubMed1983

Three-dimensional stress distribution around a dental implant at different stages of interface development.

An anchor-type ceramic dental implant contained in a section of the mandibular molar region was modeled for finite element stress analysis. The distributions of stresses in the bone around the implant due to axial and transverse loading were calculated for different stages of normal and pathological development of the implant-bone interface. Highest stress concentrations are observed in the crestal region with transverse loading when spongy bone surrounds the implant immediately after surgery. Development of a lamina dura around the implant slightly reduces severe stress peaks, whereas ingrowth of connective tissue almost eliminates them.

Aluminum Oxide↗
PubMed1982

[Testing of tissue adhesive strength in bone].

In a specially designed system the adhesive strength of bone pieces glued with all relevant adhesives was determined. The experiments were performed under dry, moderate moisture and simulated in vivo conditions.

Bone and Bones↗
PubMed1979

[Reproducibility of the jaw relation record].

The jaw relations in edentulous patients were determined with the use of the gotic arch and wax bite blocks. To compare the different methods interchangeable tracing devices and wax registrations were used. This apparatus was alternatingly used by various investigators, but with the same base plate. A quick and reliable survey of the results was possible with this experimental procedure. Our study confirmed the superior reproducibility of the graphic method with centrally supported needle.

Dental Impression Technique↗
PubMedDate not supplied

[Adhesives in surgery of the skeleton system, part 2: the adhesive strength from 22 adhesives in bone surgery (author's transl)].

For the first time all relevant adhesive groups were analyzed for their adhesive strength in bone-surgery. After having glued bone pieces in a special designed system, the tensil- and shearing-strength was determined. All adhesives showed a loss of adhesive strength under in vivo-conditions. Moderate moisture increased the tensile strength in some adhesives. While the fibrin adhesive had only a low adhesive strength under simulated in vivo-conditions, the adhesives containing gelatine, epoxy resin or acrylates reached reasonable results. The relationship between chemical structure and adhesive strength will be further used for the development of a special bone adhesive as a new surgeon's tool.

Adhesiveness↗