Resonance frequency analysis of overdenture retainer implants with immediate loading

Objective: To evaluate 16 patients of both sexes with lower overdenture and upper complete dentures, by analysing the resonance frequency of the initial and late stability of implants used to retain the overdenture under immediate loading. Background: Oral rehabilitation treatment with complete dentures using implants has been increasingly more common among the specialists in the oral rehabilitation area. This is an alternative for obtaining retention and stability in treatments involving conventional complete dentures, where two implants are enough to retain the overdenture satisfactorily. Materials and methods: The Osstell (TM) Mentor device was used for the analysis in the initial period (primary stability), 3 and 15 months after the installation of the lower overdenture (secondary stability). The statistical analysis was performed with the repeated measures model (p < 0.01). Results: The implant stability quotients were observed to increase after 15 months of the rehabilitating treatment. Conclusion: The use of overdentures over two lower implants should become the treatment of choice for individuals who have a fully edentulous mandible.

An in vitro study showing the three-dimensional microenvironment influence over the behavior of head and neck squamous cell carcinoma

Objectives: The Head and Neck Squamous Cell Carcinoma (HNSCC) ranks sixth worldwide. The mechanisms of growth, invasion and metastasis of this pathology are extensively studied and generally related to specific variations in signaling pathways like the PI3K-Akt; however most of these competent studies have been performed bidimensionally, which may hide important questions. This study sought to analyze the influence of the microenvironment upon the behavior of HNSCC. Study Design: The status of pAkt, NF-kappa B and Cyclin D1 proteins was accessed through immunofluorescence and western blot methods in HNSCC cell lines originating from tongue, pharynx and metastatic lymph node when submitted to a three-dimensional culture model utilizing a matrix system. A bidimensional culture model (monolayer) was used as control. Results: The HNSCC cell lines cultured three-dimensionally exhibited a growth pattern characterized by small isolated islands, different from the control group. When the three-dimensional model was applied, two of the studied cell lines showed the same expression pattern as the bidimensional model regarding nuclear or cytoplasmatic localization, as well as reduction of all protein levels; however, the cell line originated from tongue, which specially has the epidermal growth factor receptor constitutively activated, demonstrated nuclear translocation of pAkt and also an increase in the levels of Cyclin D1. Conclusions: The results suggest the influence of the microenvironment upon the behavior of HNSCC cells due to the changed expression of proteins related to tumor growth and cellular invasion. Furthermore, intrinsically genetic conditions also played important roles over the cells, despite the culture model employed.

Influence of Ozone Gas and Ozonated Water Application to Dentin and Bonded Interfaces on Resin-Dentin Bond Strength

Purpose: To assess the influence of ozone gas and ozonated water application to prepared cavity and bonded interfaces on the resin/dentin bond strength of two-step etch-and-rinse adhesive systems (Adper Single Bond 2 [SB2] and XP-Bond [XP]). Materials and Methods: Sixty extracted human third molars were sectioned perpendicularly to their long axes to expose flat occlusal dentin surfaces. In experiment 1, dentin was treated with ozone before the bonding procedure, while in experiment 2, ozone was applied to resin/dentin bonded interfaces. In experiment 1, dentin surfaces were treated either with ozone gas (2100 ppm), ozonated water (3.5 ppm), or distilled water for 120 s, and then bonded with SB2 or XP according to manufacturers' instructions. Hybrid composite buildups were incrementally constructed and the teeth were sectioned into resin-dentin sticks (0.8 mm(2)). In experiment 2, dentin surfaces were first bonded with SB2 or XP, composite buildups were constructed, and bonded sticks obtained. The sticks were treated with ozone as previously described. Bonded sticks were tested under tensile stress at 1 mm/min. Silver nitrate impregnation along the resin/dentin interfaces was also evaluated under SEM. Results: Two-way ANOVA (adhesive and ozone treatment) detected no significant effect for the cross-product interaction and the main factors in the two experiments (p > 0.05), which was confirmed by the photomicrographs. Conclusion: Ozone gas and ozonated water used before the bonding procedure or on resin/dentin bonded interfaces have no deleterious effects on the bond strengths and interfaces.

Qualitative SEM/EDS analysis of microleakage and apical gap formation of adhesive root-filling materials

Objective: The aim of this study was to compare the correspondence between gap formation and apical microleakage in root canals filled with epoxy resin-based (AH Plus) combined or not with resinous primer or with a dimethacrylate-based root canal sealer (Epiphany). Material and Methods: Thirty-nine lower single-rooted human premolars were filled by the lateral condensation technique (LC) and immersed in a 50-wt% aqueous silver nitrate solution at 37 degrees C (24 h). After longitudinal sectioning, epoxy resin replicas were made from the tooth specimens. Both the replicas and the specimens were prepared for scanning electron microscopy (SEM). The gaps were observed in the replicas. Apical microleakage was detected in the specimens by SEM/energy dispersive spectroscopy (SEM/EDS). The data were analyzed statistically using an Ordinal Logistic Regression model and Analysis of Correspondence (alpha=0.05). Results: Epiphany presented more regions containing gaps between dentin and sealer (p<0.05). There was correspondence between the presence of gaps and microleakage (p<0.05). Microleakage was similar among the root-filling materials (p>0.05). Conclusions: The resinous primer did not improve the sealing ability of AH Plus sealer and the presence of gaps had an effect on apical microleakage for all materials.

Biological monitoring of a promissory xenogenic pin for biomedical applications: a preliminary intraosseous study in rats

Objectives: Over the last years, it is known that in some cases metal devices for biomedical applications present some disadvantages suggesting absorbable materials (natural or synthetic) as an alternative of choice. Here, our goal was to evaluate the biological response of a xenogenic pin, derived from bovine cortical bone, intraosseously implanted in the femur of rats. Material and methods: After 10, 14, 30 and 60 days from implantation, the animals (n = 5/period) were killed and the femurs carefully collected and dissected out under histological demands. For identifying the osteoclastogenesis level at 60 days, we performed the immunohistochemisty approach using antibody against RANKL. Results: Interestingly, our results showed that the incidence of neutrophils and leukocytes was observed only at the beginning (10 days). Clear evidences of pin degradation by host cells started at 14 days and it was more intensive at 60 days, when we detected the majority of the presence of giant multinucleated cells, which were very similar to osteoclast cells contacting the implanted pin. To check osteoclastogenesis at 60 days, we evaluated RANKL expression and it was positive for those resident multinucleated cells while a new bone deposition was verified surrounding the pins in all evaluated periods. Conclusions: Altogether, our results showed that pins from fully processed bovine bone are biocompatible and absorbable, allowing bone neoformation and it is a promissory device for biomedical applications.

Treatment of central giant cell lesions using bisphosphonates with intralesional corticosteroid injections

Central giant cell lesions are benign intraosseous proliferative lesions that have considerable local aggressiveness. Nonsurgical treatment methods, such as intralesional corticosteroid injections, systemic calcitonin and interferon have been reported. Recently, bisphosphonates have been used to treat central giant cell lesions. A case of a 36-year-old male with a central giant cell lesion crossing the mandibular midline was treated with intralesional corticosteroids combined with alendronate sodium for the control of systemic bone resorption. The steroid injections and the use of bisphosphonates were stopped after seven months when further needle penetration into the lesion was not possible due to new bone formation. After two years, the bony architecture was near normal, and only minimal radiolucency was present around the root apices of the involved teeth. The patient was followed up for four years, and panoramic radiography showed areas of new bone formation. Thus far, neither recurrence nor side effects of the medication have been detected.

Porphyromonas gingivalis infection at different gestation periods on fetus development and cytokines profile

Oral Diseases (2012) 18, 648654 Aim: Infective agents may affect pregnancy outcomes by deregulating homeostasis. Objectives: The effects of Porphyromonas gingivalis infection before and at different gestation periods were evaluated. Materials and Methods: Wistar rats infected via subcutaneous with P. gingivalis W83, one week before mating (BM), days 1 (PR1) and 11 of gestation (PR11), and controls were evaluated, and samples were obtained at the end of gestation. P. gingivalis was detected by PCR. Cytokine was determined by ELISA. Results: Infected rats had lower maternal gain of weight. Implantation was not observed in 2/12 BM rats. PR11 presented more fetal-placental resorptions and lower placenta/fetus weight than controls. P. gingivalis was detected in placenta and fetus. IL-6 and TNF-a levels were higher in placenta and serum of infected groups, except for TNF-a in placenta of PR1. IL-1 beta levels were higher in placenta of PR11, but lower in serum and placenta of PR1. There were no differences in IL-10 and PGE2 concentrations among the groups (P < 0.05). Conclusions: The experimental infection by P. gingivalis resulted in alterations in the gestational pattern and in fetal development. The consequences of infection at mid-gestation were more severe than at the beginning, possibly due to the induction of pro-inflammatory cytokines in the fetal compartment.

Micro-mechanical bond strength tests for the assessment of the adhesion of GIC to dentine

Background. The aim of this study is to critically evaluate the bond strength (BS) of Glass-Ionomer Cements (GIC) to dentine with microtensile (mu TBS) and microshear (mu SBS) BS tests by assessing their rankings and failure patterns. Methods. Samples were made on flat dentine surfaces and submitted to mTBS and mSBS. The materials used were: high viscosity GIC (Ketac (TM) Molar Aplicap-KM), resin-modified GIC (Fuji II-FII), nano-filled resin-modified GIC (Ketac (TM) N100-N100) and an etch-and-rinse adhesive system with a composite resin (Adper (TM) Single Bond 2 and Z100 (TM)-Z100). All tests were performed with a Universal Testing Machine (24 h water storage, crosshead speed of 1 mm/min). Debonded surfaces were examined with a stereomicroscope (x40) to identify the failure mode. The data was analyzed with two-way ANOVA (p < 0.05) and LSD test. Results. Means were statistically different regarding the tests and materials, indicating that values for BS obtained for each material depend on the test performed. Failure analysis revealed that failures produced by mTBS were mainly cohesive for KM and FII. mu SBS failures were mainly adhesive or mixed for all materials. For the mTBS, the rank was Z100 > FII > KM = N100, whereas for the mSBS it was Z100 = FII = KM > N100. Conclusion: It may be concluded that distinct micro-mechanical tests present different failure patterns and rankings depending on the material to be considered.

Effect of Si addition on Ca- and P-impregnated implant surfaces with nanometer-scale roughness: an experimental study in dogs

Objectives: To investigate the effect of Si addition on a nanometer-scale roughness Ca and P implant surfaces in a canine tibia model by biomechanical and histomorphometric evaluations. Material and methods: The implant surfaces comprised a resorbable media CaP microblasted (control) and a CaP resorbable media + silica-boost microblasted (experimental) surfaces. Surfaces were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and optical interferometry (IFM) down to the nanometric level. The animal model involved the bilateral placement of control (n = 24) and experimental surface (n = 24) implants along the proximal tibiae of six dogs, remaining in vivo for 2 or 4 weeks. After euthanization, half of the specimens were torquedto- interface failure, and the other half was subjected to histomorphologic and bone-to-implant contact (BIC) evaluation. Torque and BIC statistical evaluation was performed by the Friedman test at 95% level of significance, and comparisons between groups was performed by the Dunn test. Results: IFM and SEM observations depicted comparable roughness parameters for both implant surfaces on the micrometer and nanometer scales. XPS analysis revealed similar chemical composition, except for the addition of Si on the experimental group. Torque-to-interface failure and BIC mean values showed no significant differences (P = 0.25 and 0.51, respectively) at both 2- and 4-week evaluation points for experimental and control groups. Early bone healing histomorphologic events were similar between groups. Conclusions: The experimental surface resulted in not significantly different biomechanical fixation and BIC relative to control. Both surfaces were biocompatible and osseoconductive.

Proteomic analysis of Porphyromonas gingivalis exposed to nicotine and cotinine

Cogo K, de Andrade A, Labate CA, Bergamaschi CC, Berto LA, Franco GCN, Goncalves RB, Groppo FC. Proteomic analysis of Porphyromonas gingivalis exposed to nicotine and cotinine. J Periodont Res 2012; 47: 766775. (c) 2012 John Wiley & Sons A/S Background and Objective: Smokers are more predisposed than nonsmokers to infection with Porphyromonas gingivalis, one of the most important pathogens involved in the onset and development of periodontitis. It has also been observed that tobacco, and tobacco derivatives such as nicotine and cotinine, can induce modifications to P. gingivalis virulence. However, the effect of the major compounds derived from cigarettes on expression of protein by P.gingivalis is poorly understood. Therefore, this study aimed to evaluate and compare the effects of nicotine and cotinine on the P.gingivalis proteomic profile. Material and Methods: Total proteins of P gingivalis exposed to nicotine and cotinine were extracted and separated by two-dimensional electrophoresis. Proteins differentially expressed were successfully identified through liquid chromatography-mass spectrometry and primary sequence databases using MASCOT search engine, and gene ontology was carried out using DAVID tools. Results: Of the approximately 410 protein spots that were reproducibly detected on each gel, 23 were differentially expressed in at least one of the treatments. A particular increase was seen in proteins involved in metabolism, virulence and acquisition of peptides, protein synthesis and folding, transcription and oxidative stress. Few proteins showed significant decreases in expression; those that did are involved in cell envelope biosynthesis and proteolysis and also in metabolism. Conclusion: Our results characterized the changes in the proteome of P.gingivalis following exposure to nicotine and cotinine, suggesting that these substances may modulate, with minor changes, protein expression. The present study is, in part, a step toward understanding the potential smokepathogen interaction that may occur in smokers with periodontitis.

Implant-Supported Prosthesis Misalignment Related to the Dental Arch: A 14-Year Clinical Follow-up

The purpose of this study was to warn the dental community about a possible problem in function with partial implant-supported prostheses used for long periods. The misalignment between natural teeth and the implant-supported prosthesis on teeth 11 and 12, observed in a 14-year clinical follow-up, illustrates the fact. The metal-ceramic crowns were placed in 1995 after a rigorous occlusal adjustment. Evaluations were made at 4, 6, 9, and 14 years, when it was noticed that the restorations were positioned palatally and extruded in comparison with the natural teeth. After 9 years, a greater discrepancy was noticed, with anterior occlusion and esthetic changes. The possible causes have been discussed: occlusal problems, parafunctional habits, and natural movement. The first 2 options were discarded after clinical analysis and diagnosis. Therefore, the natural movement probably deriving from an interaction of mechanical and genetic factors might have been the cause. The implants do not have periodontal ligaments but rather ankylosis, so they do not suffer those movements. This case emphasizes the need to inform patients that implants can last more than 10 years in function, but this is not the case with restorations, which lose function and esthetics and must be replaced.

Evaluation of the agreement by examiners according to classifications of third molars

Objectives. This study recorded and evaluated the intra-and inter-group agreement degree by different examiners for the classification of lower third molars according to both the Winter's and Pell & Gregory's systems. Study Design. An observational and cross-sectional study was realized with forty lower third molars analyzed from twenty digital panoramic radiographs. Four examiner groups (undergraduates, maxillofacial surgeons, oral radiologists and clinical dentists) from Aracaju, Sergipe, Brazil, classified them in relation to angulation, class and position. The variance test (ANOVA) was applied in the examiner findings with significance level of p<0.05 and confidence intervals of 95%. Results. Intra- and inter-group agreement was observed in Winter's classification system among all examiners. Pell & Gregory's classification system showed an average intra-group agreement and a statistical significant difference to position variable in inter-group analysis with greater disagreement to the clinical dentists group (p<0.05). Conclusions. High reproducibility was associated to Winter's classification, whereas the system proposed by Pell & Gregory did not demonstrate appropriate levels of reliability.

Behavioural changes and occlusal splints are effective in the management of masticatory myofascial pain: a short-term evaluation

The aim of this research was to test the hypothesis that treatment with intra-oral appliances with different occlusal designs was beneficial in the management of pain of masticatory muscles compared with a control group. A total of 51 patients were analysed according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) to obtain the diagnosis of masticatory myofascial pain (MMP). The sample was then randomly divided into three groups: group I (n = 21) wore a full coverage acrylic stabilisation occlusal splint; group II (n = 16) wore an anterior device nociceptive trigeminal inhibitory (NTI) system; and group III (n = 14) only received counselling for behavioural changes and self-care (the control group). The first two groups also received counselling. Follow-ups were performed after 2 and 6 weeks and 3 months. In these sessions, patients were evaluated by means of a visual analogue scale (VAS) and pressure pain threshold (PPT) of the masticatory muscles. Possible adverse effects were also recorded, such as discomfort while using the appliance and occlusal changes. The results were analysed with KruskalWallis, anova, Tukeys and Friedman tests, with a significance level of 5%. Group I showed improvement in the reported pain at the first follow-up (2 weeks), whereas for groups II and III, this progress was detected only after 6 weeks and 3 months, respectively. The PPT values did not change significantly. It was concluded that behavioural changes are effective in the management of pain in MMP patients. However, the simultaneous use of occlusal devices appears to produce an earlier improvement.

Experimental Adhesives with Different Hydrophilicity: Microshear Test in after 1, 7, and 90 Days' Storage

Purpose: To assess the microshear bond strength of 3 experimental adhesives with different degrees of hydrophilicity after 1, 7 and 90 days of storage. Materials and Methods: The bonding effectiveness of three experimental two-step etch-and-rinse adhesives (bis-GMA, bis-EMA/bis-GMA, polybutadiene [C6H12]) and one commercial adhesive (Single Bond) to sound hydrated dentin was determined using the nnicroshear test with delimitation of the adhesive area after 1, 7, and 90 days of storage in water at 37 degrees C. Two-way ANOVA was performed at the 0.05 probability level. The fractures were classified as adhesive, cohesive in dentin, cohesive in resin, and mixed. Results: The experimental adhesives showed values in the range of 11.31 to 12.96 MPa, with polybutadiene (PBH) showing the lowest bond strengths, bis-GMA the highest, and bis-EMA/bis-GMA intermediary values. Single Bond yielded bond strengths of approximately 24 MPa. Water storage decreased the bond strength in all adhesives. Adhesive fractures were predominant in experimental adhesives, while mixed fractures were the most frequent type in the Single Bond group. Conclusion: The experimental dentin adhesives of this study were able to form resin tags, but they could not penetrate into the collagen fibers and form hybrid layers. The resulting low bond strength decreased with increasing length of storage.

Evaluation of Complete Denture Quality and Masticatory Efficiency in Denture Wearers

Purpose: This study aimed to investigate (1) the influence of complete denture quality and years of denture use on masticatory efficiency and (2) the relationship between complete denture quality and years of use. Materials and Methods: A cross-sectional study was conducted with 93 edentulous patients (mean age: 65.6 years) wearing both mandibular and maxillary dentures. Patients were classified into two categories according to years of denture use: <= 2 years and >= 5 years. Masticatory efficiency was evaluated via the colorimetric method with beads as the artificial test food. A reproducible method for objective evaluation of the technical quality of complete dentures was employed. The association between denture quality and years of denture use was analyzed using chi-square and Fisher exact tests. The results of masticatory efficiency testing were analyzed using two-way analysis of variance (with the Tukey post hoc test) in terms of years of denture use <= 2 years, >= 5 years) and denture quality (poor, average, good). Results: A significant relationship was found between denture quality and years of denture use (P < .05). Masticatory efficiency differed significantly (P < .05) between patients with <= 2 years of denture use (0.101 +/- 0.076 absorbance) and >= 5 years of use (0.068 +/- 0.076 absorbance). Masticatory efficiency was not influenced by denture quality. Conclusions: Complete denture quality and masticatory efficiency significantly decreased over time. However, complete denture quality did not influence masticatory efficiency. Int J Prosthodont 2012;25:625-630.