Upper canine inclination influences the aesthetics of a smile.

This current study investigated which angle of canine inclination (angle between canine tooth axis (CA-line) and the line between the lateral canthus and the ipsilateral labial angle (EM-line)) is perceived to be most attractive in a smile. The second objective was to determine whether laymen and dental experts share the same opinion. A Q-sort assessment was performed with 48 posed smile photographs to obtain two models of neutral facial attractiveness. Two sets of images (1 male model set, 1 female model set), each containing seven images with incrementally altered canine and posterior teeth inclinations, were generated. The images were ranked for attractiveness by three groups (61 laymen, 59 orthodontists, 60 dentists). The images with 0° inclination, that is CA-line (maxillary canine axis) parallel to EM-line (the line formed by the lateral canthus and the ipsilateral corner of the mouth) (male model set: 54·4%; female model set: 38·9%), or -5° (inward) inclination (male model set: 20%; female model set: 29·4%) were perceived to be most attractive within each set. Images showing inward canine inclinations were regarded to be more attractive than those with outward inclinations. Dental experts and laymen were in accordance with the aesthetics. Smiles were perceived to be most attractive when the upper canine tooth axis was parallel to the EM-line. In reconstructive or orthodontic therapy, it is thus important to incline canines more inwardly than outwardly.

[Muscle trauma in primary total hip arthroplasty depending on age, BMI, and surgical approach: minimally invasive anterolateral versus modified direct lateral approach]. / Muskeltrauma in der primären Hüftendoprothetik unter Berücksichtigung von Alter und BMI sowie in Abhängigkeit vom operativen Zugangsweg: Minimalinvasiver anterolateraler vs. modifizierter transglutealer Zugang.

BACKGROUND: Maximum preservation of periarticular musculature is essential for the success of total hip arthroplasty. A poorer functional outcome often occurs following total hip arthroplasty, especially in older and overweight patients and is presumed to have a muscular basis. Minimally invasive hip endoprosthetics for muscle-preserving implantation have now become established in orthopedic surgery. METHODS: A primary hip endoprosthesis was implanted in a total of 39 patients using a transgluteal (modified direct-lateral, mDL, n=19) or anterolateral minimally invasive approach (ALMI, n=20). Magnetic resonance imaging was performed preoperatively as well as 3 and 12 months after the operation. Fatty atrophy (FA) of the gluteus medius muscle was evaluated as a function of body mass index (BMI), patient age and the influence of the access route. RESULTS: In the overweight group a significantly higher FA of the gluteus medius muscle was found 3 and 12 months after the operation and a significantly higher grade FA using the standard access in contrast to the normal weight group. A significantly higher FA of the gluteus medius muscle was found in the older patient group 3 and 12 months postoperation as well as a significantly higher atrophy using the mDL access. CONCLUSIONS: Muscle trauma is demonstrably reduced using a minimally invasive access, especially in older and overweight patients. In these patients there is also a substantially higher postoperative muscular atrophy after implantation of a prosthesis than in corresponding normal weight and younger patients. The higher vulnerability and poorer capacity for regeneration of periarticular musculature means that this patient group particularly profits from a minimally invasive access route.

A new method of monitoring osteomyelitis.

Chronic infections of bone such as osteomyelitis are frequent events, especially in immunocompromised or diabetic patients, and costly on a national level. Incorrect treatment or delayed diagnosis may lead to loss of the affected extremity or mandible. The aim of this study was to assess the possible value of urinary lysylpyridinoline (LP) and hydroxylysylpyridinoline (HP) concentrations in the monitoring of mandibular osteomyelitis. Patients were assigned to the following groups: group 1 (n=85), control; group 2a (n=38), patients with active disease; group 2b (n=25), patients of group 2a 6 months after successful treatment; group 2c (n=7), patients of group 2a with ongoing osteomyelitis 6 months after treatment. The range and upper limit of normal values (HP(max) and LP(max)) were determined in group 1. Levels of LP and HP were measured by high-performance liquid chromatography and fluorescence detection. There was a significant decrease (mean 45.43% for HP and 32.12% for LP) in samples of group 2b compared to 2a (P<0.001 for HP and LP). There was a significant increase in HP values in samples from group 2c compared to 2a (P=0.018). The urinary concentrations of HP and LP appear to act as a marker of disease activity, with a decrease reflecting treatment success and an increase or stable values indicating persistent disease. An inexpensive tool (US$5 per analysis) for the monitoring of osteomyelitis is described.

Learning by doing virtually.

Selective reduction of bone without collateral damage (nerves, teeth) is essential in apicectomy. To test whether skills acquired on a virtual apicectomy simulator (VOXEL-MAN system with integrated force-feedback) are transferable from virtual to physical reality, two groups of trainees were compared. Group 1 received computer-based virtual surgical training before performing an apicectomy in a pig cadaver model. The probability of preserving vital neighboring structures was improved significantly, i.e. six-fold, after virtual surgical training (P<0.001). The average volume of the bony defects created by the trainees of Group 2 (mean: 0.47 ml) was significantly (P<0.001) larger than by the trainees of Group 1 (mean: 0.25 ml). Most importantly, the ability to objectively self-assess performance was significantly improved after virtual training. Training with a virtual apicectomy simulator appears to be effective, and the skills acquired are transferable to physical reality.

Innate immunity in human bone.

Bone has exceptional regenerative properties. Oral bone appears to be particularly resistant to infection despite exposure to oral flora, even in circumstances such as oral surgery where the thin mucosal layer covering the bone is disrupted. The goal of this study was to determine whether the innate immune system of antimicrobial peptides exists inside bone. Biopsies of non-infected and chronically infected mandibular bone were harvested from patients during maxillofacial surgical procedures. Bone biopsies from the iliac crest and fibula served as controls. Immunohistochemical staining was performed, directed against the human beta-defensin antimicrobial peptides (hBD) -1, -2 and -3. In addition, cultures of osteoblast-like cells were examined for the presence of each of the three beta-defensins and their mRNA transcripts. All three human beta-defensins were detected within the mineralized bone matrix of chronically infected mandibular bone in the vicinity of the endosteum and osteocytes. hBD-1, -2 and -3 were also found in the cytoplasm of osteocytes. Expression of all three beta-defensins was detected in each of the non-infected bone types including the controls, however, to a lesser degree than that found in the chronically infected mandibular bone. This may reflect upregulation of antimicrobial peptide expression in the presence of chronic infection. Cultures of non-infected osteoblast-like cells were found to express mRNA for each of hBD-1, -2 and -3. Immunohistochemical staining of the cultures was positive for hBD-1 and -2, but not for hBD-3. We provide the first evidence of a previously unrecognized innate immunological function of bone through the demonstration of the presence of the human beta-defensins hBD-1, -2 and -3 in bone.

Association of platelet glycoprotein Ia polymorphism with minor increase of risk for oral cancer.

AIMS: In light to association of increased platelet glycoprotein Ia (GPIa) expression with tumor invasion and metastasis in several types of cancer, we investigated the possible contribution of a common polymorphism (C807/T807), affecting the GPIa gene expression, in the development of oral cancer. METHODS: DNA samples of 110 patients with oral cancer and 114 healthy controls were examined by allele-specific polymerase chain reaction followed by electrophoretic analysis. RESULTS: The mutant T807 allele homozygotes were significantly increased in the group of patients compared to the control group (P < 0.001). Furthermore, significantly increased frequency of mutant alleles compared to controls was observed in the subgroup of patients with a positive history for cancer (P < 0.01). CONCLUSIONS: The obtained results indicate that the C807/T807 polymorphism is indeed a genetic predisposing factor which contributes to increased risk for oral cancer.

Plasminogen activator inhibitor-1 polymorphism is associated with increased risk for oral cancer.

In light of the recently observed contribution of thrombosis-related factors to carcinogenesis, we investigated the possible association of plasminogen activator inhibitor-1 (PAI-1) with increased risk for oral cancer. In DNA samples of 104 patients with oral squamous cell carcinoma and 106 healthy controls of comparable ethnicity, age and sex, we studied the 4G/5G polymorphism in the PAI-1 gene, which affects its expression. The mutant 4G allele and carrier frequencies were significantly increased in patients compared to controls (65.9% versus 49.5%; 88.5% versus 69.8% respectively, P<0.01). That increase was even higher in patients with a positive family history for thrombophilia or without one for cancer (P<0.001). Interestingly, significant difference from controls was observed only in patients with cancer stages I and II. These findings suggest that the 4G allele, by resulting in higher PAI-1 expression, is a major contributing factor in early stages of oral oncogenesis. Possibly, increased PAI-1 promotes initial development of oral cancer through regulation of cell detachment and delays further tumor progression by inhibiting vascularization.

The influence of androstadienone during psychosocial stress is modulated by gender, trait anxiety and subjective stress: An fMRI study.

Androstadienone (ANDR), a bodily secreted steroid compound, is a socially relevant chemosignal that modulates subjective and (neuro)physiological responses, predominantly in females. The impact of ANDR on stress responses in males and females has not been explored. Therefore, this fMRI study aimed to examine psychosocial stress reactions induced by mental arithmetic and social evaluation on behavioral and hormonal levels (46 participants: 15 naturally cycling females in their early follicular phase (EF), 15 females on hormonal contraceptives (HC) and 16 males); and on a neural level (40 participants: 13 EF-females, 13 HC-females and 14 males) in an ANDR and placebo treatment repeated-measures design. While no gender differences emerged in subjective ratings and performance during stress, neural activation patterns differed significantly. Besides, ANDR attenuated the post-stress increase of negative mood in all participants. Region of interest analyses showed that irrespective of treatment, males showed stronger activation of the dorsolateral prefrontal cortex (DLPFC) than females. At the whole brain level, gender differences emerged indicating stronger fronto-parietal activation in males compared to HC-females on both treatments. Males showed stronger visual and fusiform activation than EF-females under ANDR. Both female groups did not show stronger activation than males. Further, error ratio in the ANDR-stress condition was positively associated with their post-stress cortisol level and increase in subjective stress in males; and male DLPFC activity in the ANDR-stress condition was negatively associated with trait anxiety. Surprisingly, compared to HC-females, EF-female only showed stronger activation of arousal-related areas under placebo treatment. Taken together, these findings suggest that the male stress reaction under social evaluative threat was stronger than female stress reactions as a function of ANDR. More specifically, this effect on behavioral and neural stress reactions seems to depend on trait anxiety in males only. The study highlights the significance of a chemosignal in enhancing social threat that may facilitate adaptive stress responses.

Growth and transplantation of a custom vascularised bone graft in a man.

BACKGROUND: A major goal of research in bone transplantation is the ability to avoid creation of secondary bone defects. We aimed to repair an extended mandibular discontinuity defect by growth of a custom bone transplant inside the latissimus dorsi muscle of an adult male patient. METHODS: Three-dimensional computed tomography (CT) scanning and computer-aided design techniques were used to produce an ideal virtual replacement for the mandibular defect. These data were used to create a titanium mesh cage that was filled with bone mineral blocks and infiltrated with 7 mg recombinant human bone morphogenetic protein 7 and 20 mL of the patient's bone marrow. Thus prepared, the transplant was implanted into the latissimus dorsi muscle and 7 weeks later transplanted as a free bone-muscle flap to repair the mandibular defect. FINDINGS: In-vivo skeletal scintigraphy showed bone remodelling and mineralisation inside the mandibular transplant both before and after transplantation. CT provided radiological evidence of new bone formation. Postoperatively, the patient had an improved degree of mastication and was satisfied with the aesthetic outcome of the procedure. INTERPRETATION: Heterotopic bone induction to form a mandibular replacement inside the latissimus dorsi muscle in a human being is possible. This technique allows for a lower operative burden compared with conventional techniques by avoiding creation of a secondary bone defect. It also provides a good three-dimensional outcome.

Adaptive adjustment of the adolescent porcine mandibular condyle.

The effect of occlusal support during primary dentition on the mandibular condyle remains controversial. We sought to determine whether unilateral loss of occlusal support leads to quantifiable adaptive changes of the condyle. Quantitative analysis of condylar growth and spongy bone volume after unilateral removal of teeth on the left side in adolescent minipigs was examined over a period of 4 months. Serial sagittal sections of the temporomandibular joint were examined using microradiography, fluorescence microscopy, and light microscopy. The condyles on the nonextracted side showed a higher growth rate than those on the extracted side, with a 1.56-fold thicker (p = 0.003) additional vertical bone layer. This factor was greater ventrally than dorsally (p = 0.0311), increasing from dorsomedial (1.33) to ventrolateral (2.38). There was therefore a reciprocal change of the condylar surface curve between the left and right condyles. Increased condylar growth correlated with a lower subchondral spongy bone volume (7.38% difference, p = 0.002). The amount of mineralized bone matrix generated was estimated to be about 1.33-fold higher in the nonextraction side condyles compared with those on the extraction side. Thus, unilateral loss of occlusal support was shown to lead to quantifiable alterations of condylar vertical growth and spongy bone volume in minipigs.

Differential expression of Neu messenger-RNA and protein in hamster-kidney and estrogen-induced kidney tumors.

An inverse relationship between the expression of the neu oncogene and estrogen receptors has been observed in breast cancer patients. In this study, we examined neu expression in the estrogen-induced and -dependent hamster kidney tumors, in kidney and in controls to evaluate the usefulness of this animal model far studying the regulation of genes important in hormonal cancer. The expression of neu mRNA was analyzed by Northern analysis and Neu oncoprotein localization by immunocytochemistry. The Neu oncoprotein was detected in several segments of proximal and distal kidney tubules, the loops of Henle and the parietal epithelial cells of Bowman's capsule but not in the tumor. neu mRNA was expressed in renal tissue after estrogen treatment and in untreated controls, but not in kidney tumors. The absence of Neu oncoprotein and mRNA from those cell types that have previously been shown to overexpress estrogen receptors in response to estrogen, suggests that the estrogen receptor and neu genes are interdependent in this tumor system, which may thus be a useful animal model for studying the regulation of neu by estrogens.

Lack of mutations in DNA polymerase beta of estradiol-induced hamster kidney tumors: sequence of hamster DNA polymerase beta cDNA.

We examined the effects of estradiol (E2), the natural estrogenic hormone, on the structure and expression of DNA polymerase beta (DNA pol beta), a DNA repair gene, from E2-induced primary kidney tumors of twelve Syrian hamsters, their metastases, and from kidney tissues surrounding the tumors. We sequenced the coding region of the hamster DNA pol beta and found it to differ from that of the human by 11%. No mutations were detected in the entire coding region including the catalytic domain of the DNA pol beta from E2-induced primary kidney tumors, their metastases, or from kidney tissues surrounding the tumors. The expression of the DNA pol beta mRNA was also not significantly altered in E2-induced kidney tumors or in kidney tissues surrounding the tumors compared to that of control kidney tissues. These results suggest that mutations in the DNA pol beta gene may not be involved in the induction or malignant progression of hamster kidney tumors induced by E2. The nucleotide sequence of the hamster DNA pol beta described here will be useful for the study of the structure and expression of this gene.

Culture of cells gained from temporomandibular joint cartilage on non-absorbable scaffolds.

The objective of this study was to investigate the adhesion, spreading and extracellular matrix synthesis of temporomandibular joint (TMJ) derived cells on non-absorbable scaffold materials to ultimately provide a durable stress-absorbent framework within tissue-engineered disc transplants. Scaffolds were prepared by polyamide monofilaments, expanded polytetrafluoroethylene (ePTFE) monofilaments, polyglycolic acid monofilaments (control) or natural bone mineral blocks (control). These scaffolds were incubated for 2, 4 and 8 weeks under common culture conditions with cells (human and porcine) harvested from the TMJ-disc or the articular eminence. The specimens were examined by scanning electron microscopy and transmission electron microscopy. The type of collagen synthesized was analyzed by SDS-PAGE. The cells were strongly adherent to all of the materials. Independent of their origin the cells became confluent on all scaffolds within four weeks. They filled recesses loosely and covered the constructs by an envelope of dense stratified cell layers. Moreover, the cells expressed collagen type II, which is specific for chondrocytes. Thus, it could be demonstrated, that ePTFE, polyamide, polyglycolic acid and natural bone mineral have an excellent compatibility in a three-dimensional cell culture system. ePTFE and polyamide scaffolds may be well suited for the development of tissue-engineered stress-resistant articular disc transplants.

Immunocytochemical localization of C-myc and C-jun oncoproteins in hamster kidney and estrogen-induced kidney tumors.

The chronic administration of 17beta-estradiol to male Syrian hamsters for 6-7 months induces kidney tumors which express high levels of c-fos, c-myc and c-jun mRNA compared to surrounding tissue or untreated controls. In this study, we have investigated, by immunocytochemical methods, the cellular localization of c-myc and c-jun oncoproteins in estrogen-dependent kidney tumors, in kidney tissue of hamsters treated with 17beta-estradiol for 6 months and in the kidneys of age-matched controls. The c-myc oncoprotein was strongly expressed in tumors, in smooth muscle layers of arteries and in parietal epithelial cells of the glomerulus. In age-matched untreated kidneys, there was little or no staining in the glomerulus, arteries or kidney tubular cells. The c-jun oncoprotein was detected in kidney tumors and in the tubular epithelium of surrounding tissue. The immunoreactivity for c-jun oncoprotein was highest in the tumor, intermediate in estrogen-treated kidney tissue and lowest in kidney tubular cells of controls. It is concluded that the high expression of c-myc in estrogen-induced kidney tumors, in the smooth muscle layer of arteries, and in glomerular parietal epithelial cells in the kidneys of 17beta-estradiol-treated hamsters, but poor expression in control kidneys indicate an involvement of this oncoprotein in the tumorigenic process. In contrast, c-jun is expressed in untreated, in 17beta-estradiol-treated kidneys and in tumors, and may not serve as a prognostic marker in the transformation of these cells to the malignant phenotype.

Amelogenesis imperfecta in a new animal model--a mutation in chromosome 5 (human 4q21).

Candidate genes for amelogenesis imperfecta (AI) and dentinogenesis imperfecta (DI) are located on 4q21 in humans. We tested our hypothesis that mutations in the portion of mouse chromosome 5 corresponding to human chromosome 4q21 would cause enamel and dentin abnormalities. Male C3H mice were injected with ethylnitrosourea (ENU). Within a dominant ENU mutagenesis screen, a mouse mutant was isolated with an abnormal tooth enamel (ATE) phenotype. The structure and ultrastructure of teeth were studied. The mutation was located on mouse chromosome 5 in an interval of 9 cM between markers D5Mit18 and D5Mit10. Homozygotic mutants showed total enamel aplasia with exposed dentinal tubules, while heterozygotic mutants showed a significant reduction in enamel width. Dentin of mutant mice showed a reduced content of mature collagen cross-links. We were able to demonstrate that a mutation on chromosome 5 corresponding to human chromosome 4q21 can cause amelogenesis imperfecta and changes in dentin composition.

Acceleration of callus maturation using rhOP-1 in mandibular distraction osteogenesis in a rat model.

The aim of this study was to assess if the application of rhOP-1 induces accelerated consolidation of the callus in mandibular distraction osteogenesis. In seven adult Wistar rats a bilateral osteotomy of the horizontal ramus of the mandible was performed in the molar region and a custom designed distractor was mounted to the mandible. With a rate of 0.7 mm per day the device was activated bilaterally after the seventh postoperative day. After seven days of distraction two times 50 microg rhOP-1 were injected on two subsequent days directly into the callus. The contralateral side received an injection of placebo solution. The animals were killed four weeks after the end of distraction. A three-point bending test revealed a significantly higher strength of the distracted mandible in the rhOP-1 side (66.3 N vs. 30.4 N, P=0.034, paired t-test). Undecalcified histological sections were examined using microradiography and fluorescence microscopy after sequential intravital polychromic labelling. A continuous bony bridging was seen in all rhOP-1 sites and in none of the control sites. The data indicate that rhOP-1 may be an option to accelerate callus maturation in mandibular distraction osteogenesis.

Prefabrication of vascularized bone grafts using recombinant human osteogenic protein-1--part 3: dosage of rhOP-1, the use of external and internal scaffolds.

In a previous study vascularized bone grafts were prefabricated with recombinant human osteogenic protein-1 (rhOP-1) using blocks of xenogenic bone mineral (BioOss) as scaffolds. The present study addressed the dosage of rhOP-1 and the combination of an external (mould) and internal scaffold (granular BioOss). In five Göttingen minipigs six prefabrication sites in the latissimus dorsi muscles were randomly assigned to groups a-f. Moulds were prepared by shaping collagen/polylactide membranes in a cylindrical form which was filled with 1g BioOss granules and rhOP-1 (a: 0; b: 50; c, f, e: 250; d: 1000 microg of rhOP-1, a-e: cylinder open to muscle, e cylinder perforated, f: cylinder open to subcutaneous fat). After 6 weeks a dose dependency of bone density (a-d: 0%; 9.4%; 15.8%; 31.1%) and vessel density (a-d: 0.3; 2.4; 7.9; 25.4 counts/view) was observed histomorphometrically. Muscular surrounding was advantageous to subcutaneous tissue. Perforations of the membranes increased vessel density and did not impair bone formation. Bone density decreased in the proximity of the polylactide membranes. The membrane material was too soft and partly collapsed and therefore needs not to be reconsidered. The use of BioOss granules with 1000 microg rhOP-1 per gram proved to be a suitable concept for prefabrication of bone transplants.

Intra- and interobserver variability of magnetic resonance imaging for quantitative assessment of abductor and external rotator muscle changes after total hip arthroplasty.

PURPOSE: Magnetic resonance imaging (MRI) is one of the most widely used noninvasive diagnostic modalities for musculoskeletal evaluation. We conducted a retrospective study to determine whether MRI of the hip joint abductor and external rotator muscles yields reproducible findings in patients after total hip arthroplasty (THA). MATERIALS AND METHODS: MR images were obtained 12 months after THA in 10 patients and were analyzed by two independent, blinded observers. The images were analyzed on workstations with three-dimensional analysis capabilities. The readers evaluated the gluteus medius, gluteus minimus, and obturator externus muscles on the nonoperated side (NOS) and the THA side. For each of the three muscles, the readers analyzed the cross-sectional area, cross-sectional signal intensity, intensity in a region of interest (ROI), and volume on both sides. RESULTS: Unlike intraobserver variability, interobserver variability showed significant differences between the measurements for some abductor and external rotator muscles, especially for volume (p<0.001-0.02) and cross-sectional area (p<0.001-0.05) analysis of the gluteus medius and minimus muscles on the THA side but also on the NOS. There were no differences in signal intensity in the ROI (p=0.29-0.83). The coefficients of variation (CoV) of all 4 parameters quantified were lower on the NOS (average, 5.9%) than on the THA side (average, 7.3%). Analysis of the gluteus minimus muscle volume showed both higher intraobserver (18.8%) and interobserver (13.9%) variability on the THA side. CONCLUSION: MRI is an accurate and reliable test for evaluation of soft tissue structures in patients who have undergone THA. MRI evaluation of abductor muscles yields reproducible results on the THA side and on the NOS. Prosthesis artifacts limit evaluation of the gluteus minimus muscle on the THA side and cannot be recommended. Since interobserver variability was always higher than intraobserver variability, follow-up examinations should ideally be performed by the same reader in order to obtain clinically meaningful results.

Mirror, mirror on the wall : self-perception of facial beauty versus judgement by others.

In 1878, Margaret Wolfe Hungerford published a simple but insightful phrase in her novel 'Molly Bawn' that was to be quoted so often it has almost become cliché: "Beauty is in the eye of the beholder". While many questions regarding the perception and neural processing of facial attractiveness have been resolved, it became obvious to us that study designs have been principally based on either facial self-perception or perception by others. The relationship between these however, remains both crucial and unknown. Standardized images were taken of 141 subjects. These 141 subjects were asked to complete the adjective mood scale (AMS) and to rank specific issues related to their looks on a visual analogue scale. The images were then shown to independent judges to rank specific issues related to their looks on a visual analogue scale. Our results show proof for a strikingly simple observation: that individuals perceive their own beauty to be greater than that expressed in the opinions of others (p < 0.001). This observation provides insight into our basic behavioural patterns and suggests that there are strong psychological mechanisms in humans supporting self-identification and thereby encouraging the self-confidence and resilience necessary to maintain one's social standing. While the psychological basis of self-confidence is multifactorial, our finding provides critical objective insight. We prove here for the first time that nothing more than the beauty of the beholder is in the eyes of the latter.