Intracanal temperature rise evaluation during the usage of the System B: replication of intracanal anatomy

AIM: To evaluate and determine intracanal temperature rises at 2 and 4 mm from the working length (WL) necessary to obtain proper replication of intracanal anatomy with gutta-percha (GP) using the System B heat source during vertical condensation. METHODOLOGY: A split-tooth model was prepared and artificial shallow depressions were cut in the buccal canal wall 2 and 4 mm from the WL. At the same level on the palatal wall holes were drilled to adapt two thermocouples. The canal was filled using GP in a vertical condensation technique by placing the System B plugger at 2 and 4 mm from the WL in groups A and B, respectively. Two control groups in which no GP was used were carried out placing the plugger 2 and 4 mm from the WL (groups A.c and B.c, respectively) and activating the heat source. Recording of temperature rise was carried out during the filling procedure for groups A and B and during activation for control groups A.c and B.c; the highest temperatures were recorded. After each filling was completed, 3 min were allowed for the GP to cool and the model divided to reveal the filling. Images of the GP were taken with a CCD camera to evaluate the presence of replication of artificial round depressions. In control groups, the temperature was recorded for 20 s after a 3 s activation of the heat source. The rise in temperature was compared between the groups individually at each level (2 or 4 mm) and statistically analysed using one-way anova and Fisher PLSD tests at 5% of significance level (P < 0.05). RESULTS: Mean temperature rises of 14 +/- 3 and 12 +/- 2 degrees C at 2 and 4 mm from the WL, respectively, were observed in group A fillings, and 4 +/- 1 and 6 +/- 1 degrees C at 2 and 4 mm, respectively, in group B fillings. Recordings at 2 mm showed significantly (P < 0.05) higher temperature rises with group A.c when compared with groups B and B.c. Replication of intracanal anatomy with GP was always found in group A fillings at both levels but only 4 mm from the WL in group B fillings. CONCLUSIONS: Positioning the plugger close to WL and a temperature rise of 6 degrees C were necessary to obtain replication of intracanal anatomy. A mean temperature rise of 4 degrees C at 2 mm from WL (group B) resulted in no replication of intracanal anatomy. Further studies simulating clinical conditions are necessary.     

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.     

Double-blind study on materials testing with applied kinesiology

Applied Kinesiology (AK) is a scientifically unproven method used in complementary medicine to recognize the (in)tolerance of dental materials. Test-retest reliability of AK was examined. The working hypothesis was the assumption that the reliability of AK would not exceed random chance. Two dentists qualified in AK examined 112 volunteers to determine individual (in)tolerance toward two dental composite materials. After the first examination, 31 subjects were excluded from further testing. At the end of the open test phase, 34 of 81 participants had been classified as "tolerant", and seven as "intolerant" to both materials. The remaining 40 individuals showed a combination of either tolerant (to material I)/intolerant (to material II), or the reverse (n = 20 each). Retrieval rate was tested under blind conditions. In 14 cases, the results of the open and blinded tests matched, whereas in 26 cases they did not (95% confidence interval, 21%-52%; p = 0.98). This outcome confirmed our working hypothesis.     

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.     

Critical appraisal. To bevel or not in anterior composites

Composites are widely used for the functional and esthetic restorations of anterior teeth. The placement of a cavosurface margin bevel on the enamel margins of anterior composite preparations traditionally has been recommended to enhance retention and for esthetic reasons, as bevels result in a gradual transition between the restoration and the tooth. However, advances in adhesive and composite technology, as well as careful composite selection and application techniques, have made it possible to place adequate anterior composites without a bevel. Elimination of bevels results in more conservative cavity preparations, a simpler technique, a reduced restored surface area, and the preservation of tooth structure when the restoration is replaced. This Critical Appraisal summarizes clinical reviews and laboratory publications related to the influence of cavity preparation and, more specifically, cavosurface bevels on the performance of anterior composite restorations.     

Neglected child with substance abuse leading to child abuse: a case report

Child abuse and neglect is any interaction or lack of interaction between a caregiver and a child resulting in nonaccidental harm to the child's physical and developmental state. Substance abuse is ingestion of any drug, which is capable of altering the mental functioning eventually leading to addiction. This paper presents a case report of a 12-year-old neglected girl with substance abuse for which she was physically abused by her mother.     

Diversity of Veillonella spp. from sound and carious sites in children

Detailed data on the distribution of Veillonella in caries-free and caries-active subjects are scarce. We hypothesized that the diversity of the genus would be lower in caries lesions than in plaque from caries-free individuals. The proportions of Veillonella were not significantly different in the two groups. All isolates (n = 1308) were genotyped by REP-PCR, and different genotypes (n = 170) were identified by 16S rRNA, dnaK, and rpoB sequencing. V. parvula, V. dispar, and V. atypica were in both groups, V. denticariosi only in caries lesions, and V. rogosae only from the caries-free individuals (p < 0.009). Lesions were more likely to harbor a single predominant species (p = 0.0018). The mean number of genotypes in the lesions was less than in the fissure (p < 0.001) or buccal (p = 0.011) sites. The Veillonella from caries-free sites were more diverse than those from caries lesions, and may be related to the acidic environment of caries lesions.     

Assessing the competency of University of Malaya dental graduates: employers' and graduates' perceptions

A survey was conducted to assess competencies of dental graduates of the Faculty of Dentistry, University of Malaya, as perceived by the graduates and their employers, based on the five-year undergraduate curriculum introduced in 1995. All senior dental officers in the Ministry of Health (MOH), representing employers, and all 164 dental graduates of the years 2000, 2001, and 2002 were sent a self-administered questionnaire covering eight areas of competency. The respondents had to rate these areas on a scale of 1 (very poor) to 4 (very good). The responses for each area were then dichotomized into poor (1 and 2) and good (3 and 4). If less than 60 percent of the respondents rated an area as good, then it was categorized as needing attention; 60-69 percent as satisfactory; and 70 percent and above as excellent. One hundred and six graduates (64.6 percent) and twenty-nine employers (96.7 percent) responded; of the graduates, 73.6 percent were working in the MOH and 22.6 percent in private practice. About 57.1 percent of employers reported that at least five graduates have worked under them. Graduates (85.7 percent) and employers (83.3 percent) agreed that graduates have excellent skills in communication. Although all graduates perceived their competency to be excellent in the four areas (treatment planning; community-based skills; management, administrative skills, and personal management; and professional development skills), employers felt that these are the areas that are of concern and needed attention. In conclusion, whilst generally the graduates' level of competency in almost all areas is acceptable or good, there are areas of concern that need to be addressed to further improve the five-year curriculum at the University of Malaya.