Preoperative radiochemotherapy and radical resection for stages II to IV oral and oropharyngeal cancer: grade of regression as crucial prognostic factor

The purpose of this study was to assess the prognostic value of histological response to preoperative radiochemotherapy in an established multimodal therapy concept for advanced oral and oropharyngeal cancer. Two hundred and twenty-two patients who underwent preoperative radiochemotherapy (RCT: 50 Gy, mitomycin C and fluorouracil) and radical surgery were retrospectively evaluated. Resected tumours of all patients were histologically analysed and response to RCT was classified in histopathological grades of regression (RG). In a multivariate statistical analysis, RG was compared with established factors regarding their predictive value for overall and disease-specific survival. The 5-year overall survival probability in the different groups of histopathological regression grades were: RG1 (no vital tumour): 73.4%, RG2 (minimal tumour remnants encompassing less than 5%): 72.1%, RG3 (5-50% vital tumour cells): 41.9%, RG4 (more than 50% vital tumour): 37.9%. For disease-specific survival probability no significant differences were found between both groups of "responders" (RG1 and RG2) nor between "non-responders" (RG3 and RG4), whereas responders and non-responders differed significantly from each other (log-rank test; p < 0.001). T-classification, N-classification and disease stage, histological grading, tumour site, age, and sex had less prognostic value than RG in a Cox regression model. In the neoadjuvant multimodal therapy concept, histological response to preoperative RCT is a crucial prognostic factor even when surgical R0-resection is accomplished. Thus, non-responders have to be regarded as high-risk patients for recurrence and may benefit from further therapy.     

An investigation of the efficacy of super-oxidised (Optident/Sterilox) water for the disinfection of dental unit water lines

AIMS: To determine the efficacy of super-oxidised water (Optident/Sterilox) in the decontamination of dental unit water lines. METHODS: Dental units (10) were first purged with concentrated super-oxidised water. After purging, a 5% (v/v) super-oxidised water was used as a maintenance dose. Samples for microbiology were taken after 0,1,2,3,4,5,6,7 d, and each week for a further 13 weeks. RESULTS: After purging, 5% (v/v) super-oxidised water was successful in reducing the microbial counts to zero, although in three of the units some bacteria were intermittently isolated in the first week of treatment. CONCLUSIONS: Super-oxidised water was successful in the removal of bacteria from dental unit water supplies. Complete removal required the treatment with a purge phase of concentrated disinfectant and a maintenance phase of at least two weeks.     

Determining the optimal obturation length: a meta-analysis of literature

The purpose was to aid in determining termination of instrumentation and obturation. A meta-analysis was conducted as to success/failure of different obturation lengths. Inclusion criteria were (a) minimum follow-up of 2 yr, (b) data on obturation length, (c) definition of success/failure, (d) available data on success/failure, (e) radiographic evaluation. Correlations were made as to success/failure as related to length of obturation from the apex. When comparing group A (obturated 0-1 mm from apex) versus group C (obturated past apex) using the DerSimonian and Laird estimates, group A showed a marginally better (p < 0.10) success rate than group C by 28.8%. Group A had better success than group B (obturated >1 mm short); the difference was insignificant. The results were similar after controlling for study quality using a single random effects regression model. In conclusion, the meta-analysis indicated that a better success rate is achieved when treatment includes obturation short of the apex.     

Microvessel density and expression of vascular endothelial growth factor, basic fibroblast growth factor, and platelet-derived endothelial growth factor in oral squamous cell carcinomas

Angiogenesis, the growth of capillary vessels, plays an important role in the metabolic functions of malignant tissues. Tumor growth and malignant transformation are considered to be dominated by uncontrolled angiogenesis. To understand the mechanism of increased vascularity associated with malignant tissues, we immunohistochemically evaluated microvessel density (MVD) and the expression of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and platelet-derived endothelial growth factor (PDGF) in oral cancers. Microvessel density did not differ significantly between normal oral mucosa and epithelial dysplasia, but was significantly increased in tumor tissues. Expression of angiogenic factors was not found in normal oral mucosa, but increased in association with increasing vascularity in OSCC tissue. In tumor tissue, angiogenic factor expression correlated with MVD. MVD in OSCC was related to T stage, tumor differentiation, and stage of invasion. VEGF expression also correlated with tumor differentiation and the stage of invasion. These findings suggest that VEGF might play an important role in tumor angiogenesis of OSCC.     

Dendritic-NK cell interactions in P. gingivalis-specific responses

Patients with localized aggressive periodontitis have type-1 cytokines in gingival crevicular fluid and high titers of IFN-gamma-dependent IgG2 reactive with P. gingivalis in gingival crevicular fluid and serum. Localized aggressive periodontitis monocytes spontaneously differentiate into dendritic cells that can stimulate IFN-gamma production by NK cells. These relationships prompted the hypothesis that P. gingivalis-dendritic cell-NK cell interactions might promote type-1 cytokine responses. Although P. gingivalis is not a potent inducer of Th1 responses, it stimulated strong IL-12 responses by monocyte-derived dendritic cells in the presence of IFN-gamma, and IFN-gamma was produced by NK cells within 24 hrs in the presence of dendritic cells. Anti-P. gingivalis IgG2 responses were enhanced by dendritic cells, and removal of NK cells reduced IFN-gamma- and P. gingivalis-specific IgG2. Thus, P. gingivalis-dendritic cell-NK cell interactions apparently resulted in reciprocal stimulation and increased type-1 cytokine production by both dendritic cells and NK cells, and increased P. gingivalis-specific IgG2.     

Automatic hole repairing for cranioplasty using Bézier surface approximation

Cranioplasty is the procedure that repairs holes or defects in the skull with cranial implants. When the bone from the hole is missing, damaged, or infected, the defect needs to be covered with an artificial plate to protect the brain. In this study, a hole-repairing algorithm is developed to aid shaping artificial plates for cranioplasty by describing a method for filling holes in defective biomodels with unstructured triangular surface meshes or in stereolithography format. The resulting patching meshes interpolate the shape and density of the surrounding mesh. The steps in repairing a hole include hole identification, hole triangulations using genetic algorithm (GA) optimization, and a customized advancing-front meshing technique using surface approximations based on a Quartic Bézier Gregory patch.     

Platelet-derived growth factor stimulates bone fill and rate of attachment level gain: results of a large multicenter randomized controlled trial

BACKGROUND: Growth factors are generally accepted to be essential mediators of tissue repair via well-established mechanisms of action that include stimulatory effects on angiogenesis and cellular proliferation, ingrowth, differentiation, and matrix biosynthesis. The aim of this study was to evaluate in a large-scale, prospective, blinded, and randomized controlled clinical trial the safety and effectiveness of purified recombinant human platelet-derived growth factor (rhPDGF-BB) mixed with a synthetic beta-tricalcium phosphate (beta-TCP) matrix for the treatment of advanced periodontal osseous defects at 6 months of healing. METHODS: Eleven clinical centers enrolled 180 subjects, each requiring surgical treatment of a 4 mm or greater intrabony periodontal defect and meeting all inclusion and exclusion criteria. Subjects were randomized into one of three treatment groups: 1) beta-TCP + 0.3 mg/ml rhPDGF-BB in buffer; 2) beta-TCP + 1.0 mg/ml rhPDGF-BB in buffer; and 3) beta-TCP + buffer (active control). Safety data were assessed by the frequency and severity of adverse events. Effectiveness measurements included clinical attachment levels (CAL) and gingival recession (GR) measured clinically and linear bone growth (LBG) and percent bone fill (% BF) as assessed radiographically by an independent centralized radiology review center. The area under the curve (AUC), an assessment of the rate of healing, was also calculated for CAL measurements. The surgeons, clinical and radiographic evaluators, patients, and study sponsor were all masked with respect to treatment groups. RESULTS: CAL gain was significantly greater at 3 months for group 1 (rhPDGF 0.3 mg/ml) compared to group 3 (beta-TCP + buffer) (3.8 versus 3.3 mm; P = 0.032), although by 6 months, this finding was not statistically significant (P = 0.11). This early acceleration of CAL gain led to group 1 exhibiting a significantly greater rate of CAL gain between baseline and 6 months than group 3 as assessed by the AUC (68.4- versus 60.1-mm weeks; P = 0.033). rhPDGF (0.3 mg/ml)-treated sites also had significantly greater linear bone gain (2.6 versus 0.9 mm, respectively; P < 0.001) and percent defect fill (57% versus 18%, respectively; P < 0.001) than the sites receiving the bone substitute with buffer at 6 months. There was less GR at 3 months in group 1 compared to group 3 (P = 0.04); at 6 months, GR for group 1 remained unchanged, whereas there was a slight gain in gingival height for group 3 resulting in comparable GR. There were no serious adverse events attributable to any of the treatments. CONCLUSIONS: To our knowledge, this study is the largest prospective, randomized, triple-blinded, and controlled pivotal clinical trial reported to date assessing a putative periodontal regenerative and wound healing therapy. The study demonstrated that the use of rhPDGF-BB was safe and effective in the treatment of periodontal osseous defects. Treatment with rhPDGF-BB stimulated a significant increase in the rate of CAL gain, reduced gingival recession at 3 months post-surgery, and improved bone fill as compared to a beta-TCP bone substitute at 6 months.     

The causes, prevention, and clinical management of broken endodontic rotary files

Complications can occur during many dental procedures. The prepared clinician responds by either correcting the problem during treatment, or, ideally, preventing the problem from occurring in the first place. In endodontic treatment separated rotary Ni-Ti files are a common procedural problem. Through understanding that the main causes of file breakage are cyclic fatigue and torsional stress, a dentist can best prevent this occurrence by using hand files before rotary files, creating a straight-line (glide path) access into a canal, and preflaring the coronal portion before using rotary files in the apical third of the canal. In addition, using an up and down motion with the electric slow-speed handpiece (not allowing the file to bind within the canal) will significantly reduce the incidence of file breakage. If a file does break, successful removal primarily depends on the location of the file in the canal rather than the specific technique employed for removal. A case does not necessarily fail if the separated file cannot be removed. The prognosis when file separation occurs can still be favorable, especially if care was taken to reduce the critical concentration of canal debris with hand instrumentation and chemical irrigation prior to rotary file insertion. In addition, the introduction of a new CS file design will help the dentist increase the chance of removing the file in the event of breakage.