Factors affecting small dental business in rural Germany: Evidence from Hessen.

OBJECTIVES: To determine how social factors influence career decisions of dental service providers, particularly focusing on examining the impact of dentists' origins. METHODS: Online survey of Hessian panel dentists, with pairwise comparisons to a set of factors impacting their decision-making process. An Analytic Hierarchy Process examined the weighting of influencing drivers in career choice. RESULTS: Dentists from rural backgrounds were more likely to establish practices in rural areas than those from urban origins. Origin correlated with entrepreneurial intentions and a strong association of rural origin. Dentists who grew up in rural areas were 4.19 times more likely to start a business. CONCLUSION: These findings may support efficient resource allocation and support for rural dental businesses.

A chemiluminescent light system in combination with toluidine blue to assess suspicious oral lesions-clinical evaluation and review of the literature.

OBJECTIVES: The aim of the study was an evaluation of an acetic acid wash and chemiluminescent light system in combination with toluidine blue in order to detect visual identified, potentially malignant lesions. MATERIALS AND METHODS: Forty-four patients with 50 oral lesions of primary uncertain visible dignity were included. Next to a clinical examination, a screening with ViziLite® (VL) as well as toluidine blue (TB; together ViziLite® Plus (VLP)) was conducted. Histopathology served as gold standard and sensitivity (SE), specificity (SP), positive as well as negative predictive value (PPV, NPV) was calculated descriptively. Additionally, a PubMed literature search using the key words "ViziLite" and "chemiluminescence oral cancer" was conducted. RESULTS: Histological diagnosis showed 40 lesions of reactive/inflammatory nature, moderate dysplasia (n = 3) and oral squamous cell carcinoma (OSCC n = 7). All OSCCs and one dysplasia were identified correct via clinical diagnosis (SE 90 %, SP 100 %, PPV 100 %, NPV 97.5 %). VL examination could show all malignancies with low specificity (SE 100 %, SP 30 %, PPV 26 %, NPV 100 %). TB and VLP were positive in all cases of cancer and in one case of inflammation (SE 80 %, SP 97.5 %, PPV 89 %, NPV 95 %). In the review, eight clinical trials with similar results were included. CONCLUSIONS: The adjunct of TB to VL reduces the number of false positives without increasing the rate of false negatives. CLINICAL RELEVANCE: Clinical evidence to justify the additional cost of the system for diagnosis of suspicious lesions is weak. However, for the potential role of VLP in detection of lesions not otherwise identified in the visual exam in general dental practice further studies are required.

Prospective, blinded comparison of cytology and DNA-image cytometry of brush biopsies for early detection of oral malignancy.

OBJECTIVES: Adjunctive techniques like DNA image cytometry (DNA-ICM) have been attributed to enhance the diagnostic performance of oral brush biopsies. The aim of the study was an evaluation of brush biopsies, analysed according to morphological criteria and by DNA-ICM vs. histological findings in a blinded prospective trial. MATERIALS AND METHODS: Eighty eight brush biopsies of 70 patients were sampled. Only clinical suspicious but not evident malignant oral lesions were included. Clinical diagnosis was leukoplakia (n = 36), lichen planus (n = 18), verruciform erythroplakia (n = 12), erythroleukoplakia (n = 9), erosion (n = 7) and induration (n = 6). Evaluation was conducted via histology, cytology and DNA-ICM. RESULTS: Histological diagnosis revealed eight cases of squamous intraepithelial dysplasia (SIN 1 n = 6, SIN 2 n = 2), four cases of carcinoma-in situ and 25 cases of oral T1-cancer. Remaining cases were leukoplakia (n = 28), lichen planus (n = 15) and local inflammation (n = 8). Brush biopsy detected malignant lesions including SIN>1 with a sensitivity of 55% and a specificity of 100%. DNA-ICM had a sensitivity of 70% and a specificity of 100%. The combination of both methods showed a sensitivity of 76% and a specificity of 100%. The predominant reason for false negative results were sampling errors with insufficient cells (86% in brush biopsy and 100% in DNA-ICM). CONCLUSION: DNA-ICM has the potential to substantially improve the sensitivity of a pure morphological interpretation of oral brush biopsies. Method inherent sampling errors may be accountable for a lower sensitivity compared to conventional histological diagnosis. Therefore, DNA-ICM should not be used to rule out malignancy, when lesions are already clinically suspicious for oral cancer.

Associations between single-nucleotide polymorphisms of the VEGF gene and long-term prognosis of oral squamous cell carcinoma.

INTRODUCTION: Functional polymorphisms (SNPs) of the vascular endothelial growth factor (VEGF) are associated with the incidence of oral squamous cell carcinoma (OSCC). An impact of VEGF-SNPs on prognosis of OSCC patients seems possible. Therefore, correlations between prognostic parameters of OSCC patients and five VEGF-SNPs were determined. MATERIALS AND METHODS: In a retrospective long-term study, in 113 OSCC patients that underwent curative resections, five VEGF-SNPs (-1154 G/A, +405 G/C, +936 C/T, -2578 C/A, and -460 C/T) were analyzed. Associations between SNPs and prognosis (incidence of local recurrent disease, second cancer, metastases, death, total disease-free survival) were examined. RESULTS: After a mean follow-up time of 57.6 months, 32 patients had local recurrences; 15 patients had second cancer, 15 patients metastases, and 23 patients died. The mean disease-free survival was 43.1 months. A significant increased incidence of OSCC in smokers with the VEGF -2578 A/C and -460 C/T SNP was seen (each P < 0.0001). In univariate analysis, patients with advanced OSCCs (T > 2 or N > 0) together with the -1154 A/A allele had a significant worse survival and a worse disease-free survival (both P < 0.04). The same was seen for the +405 G/G SNP (both P = 0.002). In multivariate analysis, only the negative influence of the +405 G/G SNP on survival in advanced OSCCs (T > 2) could be confirmed (P = 0.002). DISCUSSION: Possible reciprocal interactions between smoking and VEGF-SNP function were observed. Multivariate analysis confirmed the VEGF +405 G/G genotype to be associated with poor survival in advanced OSCCs; a further use of this haplotype as biomarker has to be discussed.

GDF 15 as an anti-apoptotic, diagnostic and prognostic marker in oral squamous cell carcinoma.

Growth-differentiation factor 15 (GDF 15) is involved in tumor pathogenesis and its expression is increased in many types of cancers. Functional effects of GDF 15 on oncogenesis of oral squamous cell carcinoma (OSCC) remain unclear. Therefore, the aim of this study was to examine the apoptotic characteristics of GDF 15 in OSCC cell lines in vitro and to analyze serum GDF 15 concentrations as a diagnostic and prognostic tumor marker for OSCC in vivo. Caspase activity was assessed in OSCC cell lines with the Caspase-Glo 3/7 system. Serum GDF 15 concentrations from 64 patients with histopathological proven OSCC and from 30 healthy volunteers were measured using an enzyme-linked immunosorbent assay. In 21 patients, serum GDF 15 was also analyzed postoperatively. In vitro, treatment of OSCC cell lines with GDF 15 reduced Caspase 3/7 activity significantly (p<0.05). In vivo, serum GDF 15 concentrations of the OSCC patients in all stages of OSCC were significantly higher than those of the healthy subjects (p<0.0001). After surgery, GDF 15 concentrations declined significantly from 1545±774pg/ml preoperative to 953±438pg/ml postoperative (p=0.003). The median survival time of OSCC patients with GDF 15 levels below 875pg/ml was significantly higher than of OSCC patients with GDF 15 levels above or equal 875pg/ml (p=0.031). Determination of receiver operating characteristic curves (ROC) showed a respective area under the ROC curve (AUC) of 0.943. The anti-apoptotic effect of GDF 15 in OSCC cell lines was shown in vitro. In vivo, significant elevated serum GDF 15 levels with prognostic value in OSCC-patients were seen for the first time. The results indicate that GDF15 may be used as a potential marker for diagnosis and prognosis of this entity.

Influence of class M1 glutathione S-transferase (GST Mu) polymorphism on GST M1 gene expression level and tumor size in oral squamous cell carcinoma.

Glutathione S-transferases (GST) are antioxidant enzymes and oxidative stress markers in oral carcinogenesis. They present a system of polymorphic proteins. Some variants are associated with increased sensitivity to toxic compounds, as it is known for the GSTM1-null variant allele. However, the influence of the GSTM1 allele variant genotype on GSTM1-mRNA quantity in oral squamous cell carcinoma (OSCC) and normal mucosa as well as the impact on prognosis remains unclear. The genotype for GSTM1 (mutation vs. wild type) was determined by polymerase chain reaction (PCR) using genomic DNA extracted from peripheral blood from 28 OSCC patients. From the same patients, 28 pairs of OSCC cells and normal oral mucosal cells were obtained by brush biopsy. mRNA was extracted from these paired samples and the expression levels of GSTM1 were examined by real-time reverse transcriptase qPCR (RT-qPCR). The mRNA expression of the OSCC samples was normalized against an external standard, as well as to the corresponding normal mucosa. The coincidence of GSTM1 genotype and GSTM1-mRNA-expression level was examined. In 15 patients (54%), the null genotype GSTM1 was present. In the GSTM1-null allele group, the GSTM1 gene expression level was determined at 1.63 (mean: 3.08; SD 3.4) folds vs. 3.6 (mean: 10.5; SD 14.2) folds in the group with the positive genotype (p=0.06), if calibrated vs. individual normal mucosa. More T3 and T4 OSCCs (+38%), higher UICC stadia (+38%) and more lymphatic metastasis (+28%) were seen in the group with the negative allele. Furthermore, positive GSTM1 genotype and enhanced GSTM1 gene expression was accompanied with increased tumor size, lymphatic metastasis status and UICC stadium. A coincidence of null type GSTM1 and lowered GSTM1 gene expression was observed. The larger tumors and more frequent lymph node metastases in this group could be explained by the insufficient cell protection by GST.

Osseointegration of one-piece zirconia implants compared with a titanium implant of identical design: a histomorphometric study in the dog.

OBJECTIVE: The aim of this study was to evaluate osseointegration of one-piece zirconia vs. titanium implants depending on their insertion depth by histomorphometry. MATERIAL AND METHODS: Four one-piece implants of identical geometry were inserted on each side of six mongrel dogs: (1) an uncoated zirconia implant, (2) a zirconia implant coated with a calcium-liberating titanium oxide coating, (3) a titanium implant and (4) an experimental implant made of a synthetic material (polyetheretherketone). In a split-mouth manner they were inserted in submerged and non-submerged gingival healing modes. After 4 months, dissected blocks were stained with toluidine blue in order to histologically assess the bone-to-implant contact (BIC) rates and the bone levels (BL) of the implants. RESULTS: All 48 implants were osseointegrated clinically and histologically. Histomorphometrically, BL in the crestal implant part did not differ significantly with regard to material type or healing modality. The submerged coated zirconia implants tended to offer the most stable crestal BL. The histometric results reflected the different healing modes by establishing different BL. The median BIC of the apical implant part of the zirconia and titanium group amounted to 59.2% for uncoated zirconia, 58.3% for coated zirconia, 26.8% for the synthetic material and 41.2% for titanium implants. CONCLUSIONS: Within the limits of this animal study, it is concluded that zirconia implants are capable of establishing close BIC rates similar to what is known from the osseointegration behaviour of titanium implants with the same surface modification and roughness.