Biomedical subjects

K L Gerlach

Publications and source records attributed to K L Gerlach.

At least 19 recordsLinked to original sources

PubMed2006

[Quantitative determination of thermosensitivity after mandibular sagittal split osteotomy].

BACKGROUND: To determine the temperature- and pain thresholds of patients (n=20) who had undergone mandibular sagittal split osteotomy (MSSO), we developed a specific thermal probe to evaluate the neurosensory disturbances of the inferior alveolar nerve under prospective study conditions. METHODS: Measurements were performed prior to surgery and postoperatively up to 6 months. Thermal probe test results were compared to the results of the usual two-point discrimination test and the sharp/blunt test. Furthermore we took the subjective neurosensory perception of each patient into account. RESULTS: With focus on our newly developed thermal probe and under comparison with the preoperative results, the postoperative neurosensory tests revealed increased thresholds of up to 12.7 degrees C. Between 3 and 6 months postoperatively, quantitative resensitization could be evaluated. In contrast, the usual testing methods were not accurate enough to give valuable significant data within 3 and 6 months postoperatively. Our evaluation could also show that after 6 months thermal thresholds were up 1.5 degrees C as compared with the preoperative status. CONCLUSION: Base on our data we conclude that the newly developed thermal probe is accurate to determine neurosensory disturbances of the alveolar inferior nerve after sagittal split osteotomy. As compared with the more common testing methods, an advantage of our contemporary measurement device is the quantitative analysis of nerval function.

Adolescent↗

PubMed2005

[Mucinous sweat gland carcinoma of a toe with metastasis to the maxilla. A case report].

Malignant tumors of the maxilla are rare. In addition to primary tumors metastatic disease has to be considered. Renal cell carcinomas, carcinomas of the breast, lung and adenocarcinomas are constituting the most frequent primary lesions for maxillary metastases. To the best of our knowledge, we present the first case of a mucinous sweat gland carcinoma metastasizing to the maxilla four years after primary diagnosis. Thirty-two months after resecting the hemimaxilla, there are no signs of local recurrence. Although skin tumors only rarely develop distant metastases, sweat gland carcinomas should be included in the differential diagnosis of tumors metastasizing to the maxilla.

Adenocarcinoma, Mucinous↗

PubMed2005

[Quantitative evaluation of thermosensitivity in patients with mandibular fractures].

AIM: The temperature and pain thresholds of 30 patients with mandibular fractures were evaluated with a specially developed measuring device in a prospective study to examine neurosensory disturbances of the inferior alveolar nerve (IAN). PATIENTS AND METHODS: Measurements in 30 patients with 45 mandibular fractures were done before, immediately after, and over the course of half a year after operation. Outcomes of the thermosensitivity measurement (TSM) were compared to the results of the two point discrimination (2-PD) test, sharp/blunt test (SBT), and questioning the patients about their subjective feelings (SF). RESULTS: Post-traumatically, neurosensory testing revealed up to 2.8 degrees C (mean) increased thresholds as compared with the intact side. By contrast, post operative diagnostics clearly revealed up to 8.1 degrees C (mean) increased thresholds. Compared with the clinical sensory tests, the post-therapeutic (3-6 months postoperative) measurements with the TSM device proved a resensitization and threshold decrease by up to 3 degrees C. We found more exact and reproducible results of the TSM in comparison to those of the 2-PD and SBT for the evaluation of sensory disturbances of the IAN. Close agreements between the results of the TSM and the SF could be detected. CONCLUSION: Because of its sensitivity and accuracy in the quantitative detection of temperature and pain thresholds, the TSM is particularly suitable for evaluating neurosensory deficits and monitoring their progression.

Adolescent↗

PubMed2005

Newly-developed measuring device for the quantitative assessment of thermal and pain thresholds of peripheral nerves.

Measuring devices for the quantitative assessment of thermal and pain thresholds are either simple and only suited for inexact tests or accurate and objective but expensive. The aim was there for to develop a cost effective device to enable a short and practical test of neurosensibility under clinical conditions. The result of this development is a new thermosensibility-measuring device (TSM) consisting of the measuring unit itself and a thermal probe. The data are registered and analysed through direct data transfer to a connected PC. Investigations carried out with this device revealed the construction to be efficient and easy to handle under clinical conditions. The TSM provides the examiner with the opportunity to monitor the neurosensory function of peripheral nerves in a reproducible way.

Diagnosis, Computer-Assisted↗

PubMed2004

Fin-edge osteotome for submucous palatal osteotomy.

We describe here a new osteotome for submucous palatal osteotomy. It enables safe sectioning of the palatal suture in the submucosal plane for rapid, surgically-assisted maxillary expansion, using the approach from the piriform aperture.

Cranial Sutures↗

PubMed2003

[In vivo study of degradation of poly-(D,L-) lactide and poly-(L-lactide-co-glycolide) osteosynthesis material].

AIMS: Comparison of the degradation of poly(D,L)lactide (Resorb X) or poly(lactide-co-glycolide) (LactoSorb) in vivo. MATERIAL AND METHODS: LactoSorb and Resorb X osteosynthesis plates were fixed at the lateral aspect of the femora of 26 Chinchilla rabbits using the respective osteosynthesis screws. After intraperitoneal injection of fluorochromes the screw plate bone blocks were resected after 1, 6, 12, 14, 16, 21, 26 months and radiologic, histologic as well as fluorescence microscopic examinations were carried out. RESULTS: Newly formed bone was detectable above and beneath the polymers 1 month after the implantation. The implants were totally covered by newly formed bone after 6 months. While the LactoSorb screws were found to be as birefringent as after 1 month, in the Resorb X screws a continuous resorption by phagocytizing marrow cells starting from the periphery was detectable. Resorb X was totally resorbed in histologic slides 12 months after implantation, while total resorption of LactoSorb lasted 14 months; both polymers were replaced by marrow cells. Bone remodeling was not finished 26 months after implantation in both polymers. CONCLUSION: Resorption of Resorb X was finished earlier than the resorption of LactoSorb. Both materials were found by fluorescence microscope to be completely resorbed after 12 or 14 months, but bone remodeling of the screw holes was not yet finished 26 months after implantation.

Absorbable Implants↗

PubMed2003

[Load resistance of mandibular angle fracturs treated with a miniplate osteosynthesis].

AIMS: The aim of this study was to evaluate the load resistance of mandibular angle fractures treated with a miniplate osteosynthesis according to Champy. MATERIAL AND METHODS: We evaluated 22 completely dentate patients with fractures of the angle in addition to 15 controls. An electric test procedure for the determination of the load resistance between the incisors, canines and molars was carried out 1-6 weeks after treatment. RESULTS: At 1 week postoperatively 90 N was registered between the molars while after 6 weeks this was 148 N. This revealed only 31% and 58% of the maximal vertical load found in the controls, respectively. CONCLUSION: The minipate osteosynthesis according to Champy offers a secure method in the treatment of mandibular angle fractures with sufficient stability. Maximum voluntary bite forces were not registered during the time of healing.

Adolescent↗

PubMed2003

[Cost of miniplate osteosynthesis for treatment of mandibular fractures: a prospective evaluation].

PURPOSE: Up to now in maxillofacial surgery almost all inpatient treatments were reimbursed at the hospital's per diem rate. The real treatment cost is unknown and there is a lack of publications in this sphere. This study calculates the cost of surgical treatment of mandibular fractures. METHOD: The prospective study includes 104 patients whose mandibular fractures were treated using miniplate osteosynthesis. For each patient we took into account the time input by physicians and specialised nurses and calculated labour cost using the relevant wage rates. We added the cost for materials and drugs as well as for laboratory and radiographic examinations. Finally, we incorporated charges for the hotel and nursing components of inpatient treatment. RESULTS: The cost for the surgical treatment of mandibular fractures varied between 642 euro; for single and 1,070 euro; for triple fractures. The share of labour cost is about 1/3. Treatment cost varies with the length of hospital stay: 1,132 euro; for four days and 1,628 euro; for seven days on average. CONCLUSION: This prospective study can be compared with the recently published corresponding G-DRG rates. Moreover, the reported cost figures allow comparison with corresponding cost studies from other public health systems.

Adult↗

PubMed2003

The effect of an admixture of sodium hydrogen phosphate or heparin-coating to poly(D,L)lactide--results of an animal study.

The study was aimed at investigating the effect of an admixture of sodium hydrogen phosphate (NaP) on the pH value around degrading poly(D,L)lactide (PDLLA) and the possible improvement of PDLLA biocompatibility by coating its surface with heparin. PDLLA +/- NaP was injection-molded to form rods (20 x 3 x 2 (mm)) and cubes (3 x 2 x 2 (mm)). Half of the pure PDLLA samples were surface-coated using heparin. One rod and cube each of PDLLA, PDLLA + NaP and PDLLA/Hep were implanted into the dorsal muscles of 42 rats. From the 2nd to 52nd week after operation, pH measurements were performed in the environment around the implants. The samples were then harvested for histological and mechanical analyses. No significant decrease in pH-values was observed in the tissue around the implants. Pure PDLLA and PDLLA/Hep samples were macroscopically resorbed after 52 weeks, while the degradation of PDLLA + NaP was still in progress. Approximately 80% of the initial bending strength of PDLLA or PDLLA/Hep rods was present after six weeks, while the bending strength of PDLLA + Nap was reduced to 50% after 4 weeks. Heparin-coating of PDLLA did not improve its biocompatibility but did increase its resorption. While no significant effect of NaP on pH value was found, its admixture did reduce the mechanical characteristics of the implants.

Animals↗

PubMed2002

[Palatal distractor. An innovative approach for palatal expansion].

BACKGROUND: A method is introduced using a newly developed palatal distractor, which allows rapid transversal widening in cases of maxillary compression. METHODS: After osteotomy of the palate parallel to the sutura palatina mediana as well as to the lateral walls of the maxillary sinuses, the applied distractor permitted a transversal widening of 7.5 mm within 3 weeks. During the 3-month period of retention, multibanded orthodontic therapy could be performed. DISCUSSION: Because of the short treatment period, absence of recurrence, and easy handling for the patient this method is recommended for clinical use.

Bone Plates↗

PubMed2002

Imaging of biodegradable osteosynthesis materials by ultrasound.

OBJECTIVE: Biodegradable osteosynthesis materials are not radio-opaque and therefore not visible on conventional X-rays. The aim of this study is to investigate the use of ultrasound for imaging biodegradable materials to detect and monitor the degradation process. METHODS: Forty-six patients had two different polylactide osteosynthesis fracture plate materials used for the fixation of midfacial fractures. A 7.5 MHz ultrasound transducer with a 4.2 x 0.9 cm footprint was used by two examiners at approximately 4-month intervals over 36 months to monitor changes of the latero-orbital and infra-orbital rims. RESULTS: Intrinsically amorphous 50 : 50 poly(D,L)lactide reached the maximum of thickness (about 300% of the initial thickness) between 14 and 18 months post-implantation and was totally resorbed in clinical and ultrasound examinations 30 months post-implantation. In 85 : 15 poly(L,D)lactide plates, the maximum of thickness (about 300% of the initial thickness) was reached between 22 and 26 months post-implantation and resorption was still in progress 36 months post-implantation. CONCLUSION: Ultrasound examinations are suitable for detecting and monitoring the degradation process of biodegradable osteosynthesis plates in the peri-orbital region.

Absorbable Implants↗

PubMed2002

Bite forces in patients after treatment of mandibular angle fractures with miniplate osteosynthesis according to Champy.

Maximal biting forces were evaluated in 22 patients with mandibular angle fractures treated with miniplate osteosynthesis according to Champy. An electric test procedure for evaluating the load resistance between the incisors, canines and molars was carried out 1 to 6 weeks following the treatment and additionally in 15 controls, too. This revealed that after surgical fracture treatment 1 week postoperatively only 31%, of the maximal vertical loading found in controls was registered. These values increased to 58% at the 6th week postoperatively.

Adolescent↗

PubMed2002

Absorption kinetics of paracetamol are not influenced by high anxiety levels in preoperative patients.

OBJECTIVE: If the absorption kinetics of orally administered drugs in preoperative patients are influenced by high anxiety levels as maintained by Simpson and Stakes [1987], then this aspect would have to be taken into consideration in the preparation for surgery and would make dose adjustments necessary in such patients. METHODS: We differentiated and quantified the anxiety level in 40 patients, 4 - 5 hours prior to an operation, using the State-Trait Anxiety Inventory (STAI). Subsequently, all patients were given 1000 mg of paracetamol and serum levels were analyzed by means of HPLC. RESULTS: Over the first 3 hours after application there were no significant differences in the parameters C(max) and t(max) between patients with high levels of anxiety and patients with low levels of anxiety. However, AUC (area under curve) values were slightly higher in patients with high levels of anxiety. CONCLUSIONS: No clinically relevant differences in absorption parameters were observed in patients with high and low levels of anxiety.

Acetaminophen↗

PubMed2001

[In vivo studies of screw-bone contact of drill-free screws and conventional self-tapping screws].

Screw-bone contact (SBC) and bone remodeling of titanium drill-free screws or self-tapping screws should be compared. Each 10 titanium self-tapping miniscrews or microscrews, and each 10 titanium drill-free miniscrews or microscrews were inserted into the anterior wall of the frontal sinus of 5 Göttingen minipigs. Intraperitoneal injections of fluochromes (Xylenol, Calcein, Alizarincomplexon and Tetrazyklin) were performed between the 2nd and 9th postoperative week. The pigs were sacrificed after 6 months, the screw-bone blocks were resected and microradiographic, histologic and fluorescence microscopic examinations were carried out. In drill-free screws mean SBC was 88.4 (miniscrews) or 93.8% (microscrews). In self-tapping miniscrews mean SBC was 54.9, in microscrews 81%; the differences were significant in statistical analysis (t-test: p < 0.05). In fluorescence microscopy the amount of bone remodeling (ratio of residual versus newly formed bone) was measured. Significantly more of the residual bone was found in the region of the screw threads of drill-free screws (miniscrews: mean 71.8, microscrews: mean 67.9%) than in the region of screw threads of self-tapping screws (miniscrews: mean 33.1, microscrews: mean 42.4%; t-test: p < 0.05). The superior SBC of drill free screws in comparison to SBC of self-tapping screws and the higher amount of original bone in the threads of drill free screws explain the sufficient holding strength of drill free screws in clinical tests. Both results are important for osteosynthesis in regions where thin cortical bone is present, as in the central midface.

Animals↗

PubMed2001

Degradation of poly(D,L)lactide implants with or without addition of calciumphosphates in vivo.

The study was aimed at examining the in vivo degradation of pure poly(D,L)lactide (PDLLA) or PDLLA with an admixture of calciumphosphates. One rod (20 x 3 x 2 mm) and one cube (3 x 2 x 2 mm) of pure PDLLA, PDLLA with tricalciumphosphate (PDLLA + TCP) or PDLLA with calciumhydrogenphosphate (PDLLA + CHP), respectively, were implanted into the dorsal muscles of 50 male Wistar Albino rats. After definite intervals (from 2nd to 72nd week), pH measurements were performed in the environment of the implants. Afterwards, the cubes with their surrounding tissues were excised for histological examinations, measurements of the outer dimensions and mechanical analyses of the explanted rods were performed. No drop of more than 0.1 pH units was detectable in the tissue surrounding any type of implants. No advantageous effect of the calciumphosphates could be proved. A mild foreign body reaction could be observed around PDLLA implants. After 72 weeks, pure PDLLA had been totally resorbed from the extracellular space, the degradation of calciumphosphate-enriched PDLLA was still in progress. A large amount of inflammations occurred in the tissues surrounding PDLLA with an admixture of slowly degrading TCP or CHP, leading to two abscesses and four fistulas at PDLLA + TCP, and two abscesses and three fistulas at PDLLA + CHP implantation site. Bending strength of pure PDLLA was constant up to the 4th week post-implantation and reduced to 60% of the initial value up to the 12th week. No traces of crystallinity could be observed during the degradation of PDLLA. As a conclusion of the study, complete resorption from the extracellular space and tissue tolerance of pure PDLLA is proved. An admixture of small calciumphosphate particles is not suitable to improve the biocompatibility of PDLLA but leads to a decrease in the mechanical characteristics.

Animals↗

PubMed2001

Sensory impairment of the lingual and inferior alveolar nerves following removal of impacted mandibular third molars.

In a prospective study 1,106 impacted mandibular third molars were removed from 687 patients. Clinical, radiographic, and surgical factors were recorded. Postoperatively, we examined the modalities of common sensation in order to assess sensory deficit. The patients were followed up, until complete restitution occurred, or, if the sensibility failed to recover, for at least 6 months. A total of 3.6% of the operated sides demonstrated impairment of labial sensation, and 2.1% of lingual sensation. The vast majority of these disturbances subsided completely during the follow-up period. The incidence of persisting sensory diminution after 6 months was 0.91% for the inferior alveolar, and 0.37% for the lingual nerve. However, the degree of the persisting deficit was slight in most instances. The relationship between the recorded factors and the alteration of sensation was analysed by using the chi2 test. For the inferior alveolar nerve we found the patient's age, the development of the roots, the degree of impaction, and the radiographic position of the nerve canal to be significantly correlated to sensory deficit, as well as the surgical procedures in the depth of the socket and the intraoperative opening of the mandibular canal. As far as the lingual nerve is concerned, general anaesthesia and the individual operator were the main factors predictive of nerve damage.

Adolescent↗

PubMed2001

The effect of an addition of sodium hydrogenphosphate to poly(D,L)lactide--results of in vitro examinations.

Aim of the study was to examine the influence of sodium hydrogenphosphate (NaP) on the pH value and the mechanical characteristics of degrading poly(D,L)lactide (PDLLA). Test rods of PDLLA with or without NaP amounting to 1, 10, 25 or 50 mol per 100 mol lactate, the degradation product of PDLLA, were produced by injection molding. Molecular weight and bending strength of the rods were measured before and after an accelerated in vitro-test (55 degrees C, Ringer's solution (RS)). For a long-time degradation test PDLLA-rods with or without 1 mol% NaP were placed in RS or Soerensen buffer solution (SB, pH 7.4) at 37 +/- 1 degrees C. Measurements of pH and determination of length, volume and weight of the samples were done in 2-4 week intervals up to the 52nd week after incubation. A pH-drop was measured in RS or SB containing pure PDLLA after 28 or 36 weeks respectively. Stabilization of the pH value due to admixed NaP delayed the degradation related pH drop for 8 weeks in RS or SB. A strong increase of length, volume and weight was measured in PDLLA + NaP-rods. In conclusion minimal stabilization of pH but also an increase of outer dimensions of the samples was found due to the admixture of NaP to PDLLA. Thus, an addition of substantially higher amounts than 1 mol% NaP in PDLLA can not be recommended, regardless of the positive effects on pH stabilization.

Absorbable Implants↗

PubMed2001

Analysis of the osseous/metal interface of drill free screws and self-tapping screws.

AIM: A comparison of metal/osseous interface and bone remodelling after insertion of different types of titanium bone screws in vivo. MATERIAL: Samples of five of each of the following bone screw types were inserted into the anterior wall of the frontal sinus of five Göttingen minipigs: self-tapping micro- (1.5mm) and miniscrews (2.0 mm) or drill free micro- (1.5 mm) and miniscrews (2.0 mm) (Martin Medizintechnik, Tuttlingen, Germany). Screw length was 7mm. METHODS: Sequential intraperitoneal injections of fluorochromes were performed between the second and ninth postoperative week. After 6 months the pigs were sacrificed, the screw-bone-blocks resected, and microradiographic, histological and fluorescence microscopical examinations were carried out. RESULTS: Using drill free screws, mean screw/bone contact was 88.4% (miniscrews), or 93.8% (microscrews). With self-tapping miniscrews it was 54.9%, but in microscrews 81%; the differences were statistically significant (t-test: p<0.05). By fluorescence microscopy, the amount of bone remodelling (ratio of residual vs. newly formed bone) was measured. Significantly more of the residual bone was found in the region of the screw threads using drill free screws (miniscrews: mean 71.8%, microscrews: mean 67.9%) than in the region of screw threads with self-tapping screws (miniscrews: mean 33.1%, microscrews: mean 42.4%). CONCLUSION: The present data support the view that screw/bone contact with drill free screws was superior to that of self-tapping screws; the greater amount of original bone in the threads of drill free screws demonstrated that the insertion of drill free screws did not cause harm to the surrounding bone. Both results are important for osteosynthesis in regions where thin cortical bone is present, such as the central midface.

Animals↗