Facial self-perception, well-being, and aesthetic surgery.

BACKGROUND: It is controversial whether impaired well-being is associated with (a) an increased likelihood of having a negative body/facial image; or (b) dissatisfaction with the postoperative result following aesthetic surgery. We set out to improve current knowledge in this matter. METHODS: A total of 324 subjects (n = 162 females, n = 162 males, 18-30 years) were photographed, asked to complete the adjective mood scale and to rate 46 statements regarding their own appearance, and its impact on social functioning as well as their willingness to undergo aesthetic surgery on a visual analog scale. The photographs of these subjects were also assessed by 50 independent judges. RESULTS: Average self-awarded ratings of appearance were significantly more positive in subjects with normal as compared to those with impaired well-being (P = 0.014). Items regarding the impact of appearance on social functioning were answered significantly more negatively by subjects with impaired well-being as compared with those with the normal well-being (P = 0.001). Subjects with impaired well-being did not declare an increased willingness to undergo aesthetic surgery (P > 0.197). Assessment by the independent judges did not reveal differences in the average level of attractiveness of subjects with impaired well-being and those with normal well-being (P = 0.666). CONCLUSIONS: Impaired well-being is associated with impaired facial selfperception, independent of attractiveness. Willingness to undergo aesthetic surgery seems not to be affected by one's sense of well-being. In the subjects with impaired well-being who undergo aesthetic surgery, facial self-perception seems unlikely to be improved.

The battle against multi-resistant strains: Renaissance of antimicrobial essential oils as a promising force to fight hospital-acquired infections.

Hospital-acquired infections and antibiotic-resistant bacteria continue to be major health concerns worldwide. Particularly problematic is methicillin-resistant Staphylococcus aureus (MRSA) and its ability to cause severe soft tissue, bone or implant infections. First used by the Australian Aborigines, Tea tree oil and Eucalyptus oil (and several other essential oils) have each demonstrated promising efficacy against several bacteria and have been used clinically against multi-resistant strains. Several common and hospital-acquired bacterial and yeast isolates (6 Staphylococcus strains including MRSA, 4 Streptococcus strains and 3 Candida strains including Candida krusei) were tested for their susceptibility for Eucalyptus, Tea tree, Thyme white, Lavender, Lemon, Lemongrass, Cinnamon, Grapefruit, Clove Bud, Sandalwood, Peppermint, Kunzea and Sage oil with the agar diffusion test. Olive oil, Paraffin oil, Ethanol (70%), Povidone iodine, Chlorhexidine and hydrogen peroxide (H(2)O(2)) served as controls. Large prevailing effective zones of inhibition were observed for Thyme white, Lemon, Lemongrass and Cinnamon oil. The other oils also showed considerable efficacy. Remarkably, almost all tested oils demonstrated efficacy against hospital-acquired isolates and reference strains, whereas Olive and Paraffin oil from the control group produced no inhibition. As proven in vitro, essential oils represent a cheap and effective antiseptic topical treatment option even for antibiotic-resistant strains as MRSA and antimycotic-resistant Candida species.

Platelet-rich plasma and platelet-rich fibrin in human cell culture.

OBJECTIVES: The clinical use of platelet-rich plasma (PRP) for preprosthetic surgery has been a matter of controversy until now. Only recently, a new blood preparation has been developed which results in platelet-rich fibrin (PRF). The objective of the present investigation was to examine the growth factor release from PRP and PRF in vitro. STUDY DESIGN: Whole blood samples from healthy participants (n = 10) were drawn to generate PRP and PRF. Human osteoblasts (O), human fibroblasts (F), and human osteoblast-derived osteosarcoma cells (Saos-2) were used for the cell culture. Cells of each cell line were cultivated, and PRP- or PRF-preparations added for ten days. The drawn medium was pooled and the quantities of growth factors (platelet-derived growth factor isomers AB and BB, insulin-like growth factor I, and transforming growth factor (TGF) isomers beta1 and beta2) analyzed by enzyme-linked immunosorbent assay. RESULTS: In osteoblast and Saos-2 cultures, cytokine concentrations were significantly higher for PRP than for PRF (P < .05). In fibroblast cultures, results were the same with the exception of TGF-beta2 (P < .05). CONCLUSIONS: This study demonstrates that PRP application in cell cultures leads to higher levels of growth factors than PRF application.

Psoriasis of the tongue.

INTRODUCTION: Psoriasis is a common, chronic dermatologic disease. Cases affecting the oral mucous membranes are rarely reported in the international literature, in particular tongue lesions are hardly ever documented. MATERIAL AND METHODS: This article presents a 61 year old patient with persistent whitish lesion on his tongue. Biopsy specimens from mid surface and tip of the tongue were taken. Histopathologic sections were stained with haematoxylin-eosin (H-E) as well as with Periodic acid-Schiff (PAS) and examined by light microscopy. RESULTS: Tongue lesions showing epithelial hyperplasia, parakeratosis, long papillae, neutrophils and microabscesses of Munro. CONCLUSIONS: The reported case suggests that the clinical and histological appearances of the lesions are consistent with mucosal psoriasis.

Rapid prototyping: porous titanium alloy scaffolds produced by selective laser melting for bone tissue engineering.

Selective laser melting (SLM), a method used in the nuclear, space, and racing industries, allows the creation of customized titanium alloy scaffolds with highly defined external shape and internal structure using rapid prototyping as supporting external structures within which bone tissue can grow. Human osteoblasts were cultured on SLM-produced Ti6Al4V mesh scaffolds to demonstrate biocompatibility using scanning electron microscopy (SEM), fluorescence microscopy after cell vitality staining, and common biocompatibility tests (lactate dihydrogenase (LDH), 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT), 5-bromo-2-deoxyuridine (BrdU), and water soluble tetrazolium (WST)). Cell occlusion of pores of different widths (0.45-1.2 mm) was evaluated. Scaffolds were tested for resistance to compressive force. SEM investigations showed osteoblasts with well-spread morphology and multiple contact points. Cell vitality staining and biocompatibility tests confirmed osteoblast vitality and proliferation on the scaffolds. Pore overgrowth increased during 6 weeks' culture at pore widths of 0.45 and 0.5 mm, and in the course of 3 weeks for pore widths of 0.55, 0.6, and 0.7 mm. No pore occlusion was observed on pores of width 0.9-1.2 mm. Porosity and maximum compressive load at failure increased and decreased with increasing pore width, respectively. In summary, the scaffolds are biocompatible, and pore width influences pore overgrowth, resistance to compressive force, and porosity.

Nasal shape and gender of the observer: implications for rhinoplasty.

BACKGROUND: In a previous study we focused on gender specific nasal shapes. The aim of this study was to evaluate if preferences in nasal shape are also dependent on the gender of the observer. METHODS: Stratified on the basis of each photographed subject's (n=311) own evaluation, female and male composite pictures of "average" (n=128, each), "optimal" (n=16, each) and "most unpleasant" (n=8, each) noses were created in a previous study. These composites were assessed by 308 independent female and male judges using a visual analogue scale. RESULTS: On average, female judges were found to accord significantly higher ratings of attractiveness as compared to male judges for the composite images independent of the gender of the person shown (p=0.020). The difference was greatest when assessing most unpleasant male composites (p<0.003) but was not apparent when assessing "optimal" female and "optimal" male noses. Despite this, women displayed the same preferences for "optimal" and "average" noses as compared to the "most unpleasant" noses. In assessing their own noses, women were significantly less satisfied with their appearance in general (p=0.001) as compared to men. CONCLUSIONS: In comparison to men, women are more critical in assessing the appearance of their own nose as opposed to the noses of other people. The implications of this for rhinoplasty, so far as considering the degree of influence of the gender of a person assessing a prospective patient's nose remains a matter of conjecture.

Penicillin compared with other advanced broad spectrum antibiotics regarding antibacterial activity against oral pathogens isolated from odontogenic abscesses.

OBJECTIVES: We examined the spectrum of oral pathogens found in odontogenic abscesses and their susceptibility to penicillin as well as to amoxicillin with clavulanic acid, doxycycline, clindamycin and moxifloxacin. The in vitro results were compared with clinical observations. PATIENTS AND METHODS: One hundred and eighty eight swabs were obtained from 94 patients with odontogenic abscesses. Bacterial strains were isolated for susceptibility tests. The same patients were investigated for their clinical outcome after standard therapy. RESULTS: A total of 517 bacterial strains were isolated from 94 patients. Ninety eight per cent of abscesses were polymicrobial. The most prevalent bacteria were Viridans streptococci representing 54% of the aerobic/facultative anaerobic bacteria. Prevotella spp. comprised 53% of the anaerobes. No multiresistant strains were detected. Susceptibility testing revealed a sensitivity of over 99% of aerobes/facultative aerobes and 96% of anaerobes sensitivity for moxifloxacin. The corresponding values for penicillin were lowest at 61% and 79%, respectively. In the clinical collective, patients with minor abscesses and no risk of further progression received surgical treatment without antibiotics (36%). Penicillin was administered additionally in 30%. Amoxicillin with clavulanic acid was given in 18% and clindamycin in 15%. Ninety two of the 94 patients showed significant recovery with the described treatment. Only in two cases was a change to the latest broader spectrum antibiotics necessary. CONCLUSION: In contrast to the moderate in vitro results, penicillin successfully treated the pathogens derived from odontogenic abscess sufficiently when adequate surgical treatment was provided. One third of the patients was treated successfully with incision and drainage only. We suggest that one good reason for its clinical efficacy is the susceptibility of the dominant aerobe/facultative aerobe and anaerobe strains to penicillin.

HDR brachytherapy irradiation of the jaw - as a new experimental model of radiogenic bone damage.

INTRODUCTION: Hitherto, no suitable experimental model exists to test new treatments for radiogenic bone damage, such as new step from knowledge about bone growth factors or angiogenesis factors. The goal of this investigation was to establish such a standardised experimental model. MATERIAL AND METHODS: Twenty-four rats were used in this study. In 12 rats a plastic tube was implanted along the right half of the mandible and treated with a single dose of 20 Gy at a high-dose-rate (HDR) using an afterloading machine, the remainder served as control (n=12). One hundred days after irradiation both sides of the mandible were examined using paraffin embedding and non-decalcified histology. RESULTS: All HDR irradiated rats developed localised alopecia within 2 weeks of radiotherapy. In the irradiated group, a clear growth reduction of the ipsilateral incisor was observed. Paraffin histology revealed minimal damage of the bone structure with slightly increased signs of regeneration. The bone apposition rate was significantly reduced on the irradiated right side, compared with the left side (p=0.028). The average diameter of the mandibular condyles on the irradiated right sides was significantly reduced when compared with the left sides (p=0.023). CONCLUSIONS: It is possible to induce radiogenic damage of the mandible by using HDR brachytherapy with a single dose of 20 Gy comparable to 45 x 2 Gy of conventional irradiation. This new model is easy and predictable and appears to be suitable for the testing of new treatment modalities. It is advantageous for the testing of bone growth and angiogenesis factors that the contralateral side exhibits completely normal bone apposition characteristics enabling a split-mouth design for future experiments.

Missing osteogenic effect of expanded autogenous osteoblast-like cells in a minipig model of sinus augmentation with simultaneous dental implant installation.

OBJECTIVES: With natural bovine bone mineral (BioOss) as carrier, the study aimed at investigating the effect of autogenous osteoblast-like cells on bone regeneration in an orthotopic (maxillary sinus) and an ectopic (muscle) site. MATERIALS AND METHODS: Autogenous osteoblast-like cells were isolated from iliac cancellous bone of six minipigs and expanded in an autogenous serum-supplemented osteogenic medium. After confirmation of osteogenicity, the expanded cells were precultivated on BioOss granules for 1 week. Four milliliter of cell-seeded BioOss were used for sinus augmentation of right sinus and a Straumann solid screw (dental) implant was simultaneously installed. The contralateral (control) side was filled with cell-free BioOss. Besides, 2 ml of the corresponding granules were placed in a pouch in the latissimus dorsi muscles bilaterally. Polychrome sequential labeling was performed postoperatively. Specimens were harvested at week 6. Undecalcified sections were evaluated with microradiography, fluorescence microscopy, histology and histomorphometry. RESULTS: In the test side, the coronal part of dental implant demonstrated higher bone-implant contact (BIC) than the apical part (34.88+/-28.86% vs. 16.68+/-13.80%, P=0.039), as well as higher bone density (BD) in the corresponding zone (14.88+/-6.37% vs. 11.10+/-4.54%, P=0.021). However, the test side demonstrated no advantage over control side in either BD (12.25+/-4.22% vs. 8.45+/-11.04%, P=0.473) or BIC (24.15+/-21.97% vs. 22.05+/-19.00%, P=0.270). Rare bone was formed in the muscles in both sides. CONCLUSIONS: The expanded autogenous osteoblast-like cells failed to enhance bone formation in the minipig model of sinus augmentation.

Gender and nasal shape: measures for rhinoplasty.

BACKGROUND: Gender-specific nasal shapes are recommended for rhinoplasty. This study was conducted to clarify whether there truly are gender-related differences and to determine optimal nasal shapes in a Caucasian population. METHODS: The authors created female and male composite photographs of "average" (n = 128 each), "optimal" (n = 16 each), and "most unpleasant" (n = 8 each) noses stratified on the basis of each photographed subject's (n = 311) own evaluation of the attractiveness of her or his nose, using a visual analogue scale. These composites were also assessed by 308 independent judges. RESULTS: Optimal female noses showed a horizontally and vertically lower nasion and were concave to straight in profile as compared with optimal male noses, which had a vertically and horizontally higher nasion and a straight profile. A supratip break was not found in any of the composites. At least half of the judges rated average and optimal male composite noses as female. A significant majority mistook the composite of the most unpleasant female noses as male (frontal view, 62.0 percent; lateral view, 72.4 percent; p < 0.001). Optimal and average female and male noses were found to be independently significantly more attractive than the most unpleasant ones (p < 0.001, n = 308 judges). Women and men with a straight or concave profile were significantly (p = 0.017 and p = 0.006, respectively) more satisfied with the appearance of their nose than those with nasal humps. CONCLUSIONS: Gender-related differences in nasal shape appear to be subtle, with nasion position being one of the main factors. A nasal hump and a supratip break are not desirable.

BMP-2 and bFGF in an irradiated bone model.

INTRODUCTION: Basic fibroblast growth factor (bFGF) is considered to enhance angiogenesis and to support bone formation in the presence of vital bone cells. Bone morphogenetic protein-2 (rhBMP-2) is known to induce bone formation. The aim of this study was to analyze the effect of bFGF and rhBMP-2 in the irradiated mandible. MATERIAL AND METHODS: The right mandibles of 24 rats were irradiated with a single dose of 20 Gy at a high-dose-rate (HDR) after loading machine (bio effective equivalent dose to ca. 45 x 2 Gy). After 12 weeks 100 microg rhBMP-2 (n=6 animals, group 1), 100 microg bFGF (n=6 animals, group 2) and 100 microg rhBMP-2 plus 100 microg bFGF (n=6 animals, group 3) were injected along the right mandible (left mandible: no irradiation, no growth factor). Another 6 animals (group 4) remained untreated after the irradiation. After another 7 weeks the specimens were examined by non-decalcified histology. RESULTS: Bone apposition of the experimental versus control sides was not statistically significantly different when one of the growth factors was applied alone (rhBMP-2: p=0.917; bFGF: p=0.345). Average bone apposition was significantly decreased on the experimental sides of group 3 (rhBMP-2+bFGF: p=0.046) and group 4 (p=0.008). Average bone densities were unaffected in all settings (for all p>0.1). CONCLUSIONS: The application of bFGF and the application of rhBMP-2 alone did result in predictable bone generation in the irradiated mandible with the bone apposition being equal to that of the non-irradiated side. The application of both growth factors together or none at all after irradiation results in significantly reduced bone apposition.

Facial attractiveness: visual impact of symmetry increases significantly towards the midline.

Symmetry is thought to be a major prerequisite for an attractive face. Many faces are not symmetric, yet are still regarded as beautiful. What role, then, does asymmetry play in the perception of beauty? We studied the assessment of computer-manipulated images by independent judges (n = 200-250): part A: nevi located at different positions; part B: standardized changes of the orbital region. The results showed that slight lateral orbital and facial asymmetry does not impair attractiveness at all and that asymmetries close to the midline are significantly less attractive than those affecting the lateral aspect of the face (P < 0.001). A single nevus which is located laterally on the face is significantly more attractive than a nevus close to the midline (P < 0.001). Faces with a completely symmetric bilateral pair of nevi in the same lateral positions (perceived as attractive when alone), received the worst ratings (P < 0.001). Symmetry is a characteristic of the attractive face, but there are exceptions to the rule. Under certain conditions symmetry can be completely unattractive. The visual impact of symmetry on the perception of beauty increases significantly when approaching the midline.

Proof of direct radiogenic destruction of collagen in vitro.

BACKGROUND: Fibroses of vessels and soft tissue are side effects of radiotherapy. The authors assumed that there was an immediate direct radiogenic damage of collagen of bone, periosteum and skin. MATERIAL AND METHODS: 15 porcine jaws samples (group 1) were exposed to a total dose of 60 Gy (cobalt-60, 2 Gy/day, five fractions/week). 15 jaws samples were stored accordingly (group 2, no irradiation, control). Collagen fragments of bone, periosteum and skin samples of groups 1 and 2 were isolated by ultrafiltration. Collagen types were characterized by SDS-PAGE measurement of the mature collagen cross-links hydroxylysylpyridinoline (HP) and lysylpyridinoline (LP) by high-performance liquid chromatography (HPLC) and analysis of hydroxyproline (Hyp) was used to determine the ratio of the amount of collagen fragments from irradiated as opposed to nonirradiated samples. RESULTS: The concentrations of HP, LP and Hyp in ultrafiltrates of probes of irradiated bone, periosteum and skin were markedly increased (average factors for bone: 3.69, 1.84, and 3.40, respectively; average factors for periosteum: 1.55, 1.41, and 1.77, respectively; average factors for skin: 1.55, 1.60, and 2.23, respectively) as compared to nonirradiated probes. SDS-PAGE did show collagen types I and V in nonirradiated bone, I and III in nonirradiated skin, and I in nonirradiated periosteum samples. In irradiated samples, smeared bands illustrated fragmentation of the collagen molecule. CONCLUSION: The increased concentrations of HP, LP and Hyp in ultrafiltrates indicated increased concentrations of split collagen. Direct and instant radiogenic damage of (extracellular matrix of) bone, periosteum and skin tissue collagen could be demonstrated.

Craniectomy and noggin application in an infant model.

INTRODUCTION: Noggin is an antagonist of bone morphogenetic proteins (BMP)-2, -4 and -7. Little data are available regarding its clinical utility. Two hypotheses were put forward: firstly, that spontaneous regeneration of calvarial defects with noggin protein would result in diminished bone volume when compared with calvarial defects not so treated. Secondly, that centrifugal cranial expansion would remain undisturbed whether noggin was applied or not. MATERIAL AND METHODS: A unilateral defect of the frontal and parietal bones (2x4cm) was generated by excising the right coronal suture in 2-month-old minipigs (n=10) and in group 1 (n=5) no further intervention was undertaken. In the second group (n=5), a collagen type I tissue fleece and noggin protein (1.05mg/ml) were applied. After 4 months the coronal suture regions of frontal sides were examined in each animal by computed tomography and non-decalcified histology. RESULTS: Bony gaps of equivalent size remained in animals of both groups. The differences in bone volumes of the experimental sides of group 1 were not statistically significantly different (p=0.117) when compared with those of group 2. A significant difference in the bone volumes of the experimental versus control (unoperated) sides was found in both group 1 (p=0.043) and group 2 (p=0.043). Internal skull diameters increased by 16.4% in both groups but the physiological centrifugal cranial expansion remained undisturbed. Bone densities of the experimental and control sides of groups 1 and 2 were not statistically significantly different (both p>0.05). CONCLUSIONS: The first hypothesis was contradicted: the quantity and quality of spontaneous bone regenerates was not altered by application of noggin protein. The second hypothesis was confirmed: no disruption of subsequent cranial development was seen. It may be that a single application of noggin protein in this study was insufficient. However, it may well be suggested that the continuous supplementation of noggin, for example by adenoviral noggin gene transfer may significantly reduce the quantity of spontaneous bone regeneration in a similar experiment.

Long-term recurrence rate of pleomorphic adenoma and postoperative facial nerve paresis (in parotid surgery).

BACKGROUND: The purpose of this study was to evaluate recurrence rates and comorbidity in patients with pleomorphic adenomas of patients after superficial and total conservative parotidectomy. PATIENTS AND METHODS: Localization of pleomorphic adenomas, age, sex distribution and facial nerve function of 73 patients were examined in this retrospective study. The recurrence rate could be determined in 43 of these patients. The interval between surgery and last recall varied between 2 and 20 years (median: 8.1 years). RESULTS: Most of the patients were female (67%) with a parotid pleomorphic adenoma. No recurrence was found regard less of whether a superficial or total conservative parotidectomy had been performed. Our data did show that the total conservative parotidectomy is associated with a higher incidence of temporary impaired facial nerve function, which was seen in 42% of this group. Temporary decreased nerve function after superficial parotidectomy was rare being apparent in only 16% of this group. CONCLUSION: A more radical procedure does not significantly lower the recurrence rate. We suggest that the indication for a total conservative parotidectomy in cases of superficial adenomas should be considered carefully.

[Facial aesthetics Part II - effect of symmetric and asymmetric modulations of the orbital region]. / Gesichtsästhetik Teil 2: Auswirkung symmetrischer und asymmetrischer Veränderungen der Orbitaregion.

The aim of the present study was to assess the impact of standardised computer-manipulated changes to images of the orbital region. Judges (n=250) ranked each image for attractiveness on a visual-analogue-scale. The images were thereby classified into different clusters according to their ratings of attractiveness. These clusters were highly significantly different (p<0.001). The degree of negative impact of changes to the orbital region on facial attractiveness increased significantly from lateral to medial and from cranial to caudal. Small asymmetrical or symmetrical lateral variations did not influence attractiveness negatively.

[Facial aesthetics part I - the significance of the triangle of yarbus]. / Gesichtsästhetik Teil 1: Die Bedeutung der Symmetrieebene des Gesichts.

When humans observe a face, the eyes, mouth and nose regions are the preferred targets of the centre of gaze, with the outlines of eye position recordings approximating a triangle with vertices located in the centre of the eyes and mouth [31]. We studied the significance of cutaneous asymmetries inside and outside the Yarbus triangle on the basis of the assessment of digitally-manipulated images by 201 independent judges. We show that certain facial variations (such as naevi) are more attractive when asymmetrical than symmetrical (p<0,001). They appear more attractive when located laterally rather than medially, particularly so when located outside the Yarbus triangle as compared to inside it (p<0,001). The significance of facial symmetry increases significantly when approaching the Yarbus triangle or the midline, respectively.

Two techniques for the preparation of cell-scaffold constructs suitable for sinus augmentation: steps into clinical application.

The objective of this clinical trial was the analysis of 2 methods for engineering of autologous bone grafts for maxillary sinus augmentation with secondary implant placement. Group 1 (8 patients, 12 sinuses): cells of mandibular periosteum were cultured in a good manufacturing practice laboratory (2 weeks) with autologous serum and then transferred onto a collagen matrix. After another week, these composites were transplanted into the sinuses. In group 2A (2 patients, 3 sinuses), cells of maxillary bone were cultivated with autologous serum for 2 weeks, seeded onto natural bone mineral (NBM, diameter [Ø] = 8 mm) blocks, and cultivated for another 1.5 months. These composites were transplanted into the sinuses. Group 2B (control, 3 patients, 5 sinuses) received NBM blocks alone. In the course of implant placement 6 (group 1) and 8 (group 2) months later, core biopsy were taken. Clinical follow-up period was 1 to 2.5 years in group 1 and approximately 7 years in groups 2A and 2B. New vital bone was found in all cases at median densities of 38% (n = 12) in group 1, 32% in group 2A (n = 3), and 25% in group 2B (n = 5). Differences between group 1 and 2B as well as 2A and 2B were statistically significant ( p = 0.025). No adverse effects were seen. All methods described were capable of creating new bone tissue with sufficient stability for successful implant placement.

Increased excretion of collagen crosslinks in irradiated patients indicates destruction of collagen.

PURPOSE: In a recent study we showed an instant radiogenic destruction of collagen in dental tissues. The hypothesis of this analysis was that there is a destruction of collagen directly in bone during irradiation. Our intention was to prove this assumption by the analysis of the intraindividual progression of urinary excretion of bone specific collagen crosslinks before, during and after radiotherapy (RT) of secondary malignant bone tumors. MATERIAL AND METHODS: Forty-six patients were irradiated with a mean dose of 32 Gy (range 30 - 46 Gy). Four urine probes were collected from each patient before, during, at the end and 6 - 8 weeks after RT. Measurement of the mature collagen crosslinks hydroxylysylpyridinoline (HP) and lysylpyridinoline (LP) was performed by high performance liquid chromatography (HPLC). RESULTS: In 43 patients we found increasing HP and LP concentrations by comparing the different chosen time-points. As regards to HP the urine excretion was significantly increased at the end (p = 0.02) and six weeks after RT (p = 0.01) and for LP six weeks after RT (p = 0.01). We observed significantly higher urinary HP levels in patients treated with doses of 35 - 46 Gy as compared to patients treated with 30 Gy (p = 0.05). CONCLUSIONS: The urinary excretion of HP and LP was increased directly after a course of RT. This finding may reflect either destruction of collagen or increased bone remodeling/resorption after radiotherapy. Either way these findings suggest a relation to the mechanical instability of bone directly after radiotherapy. Future investigations of irradiated patients without osseous metastases will further clarify this matter.