Determination of pulp vitality in vivo with pulse oximetry

Aim To evaluate the use of pulse oximetry as a test for pulp vitality, by comparing in the same patient, the levels of oxygen saturation of the index finger and of the maxillary central incisor and canine teeth without clinically detectable pulp inflammation. Methodology Seventeen male and female patients aged between 26 and 38 years participated and a total of 32 maxillary central incisor and 32 canine teeth were analysed. Selection criteria required the teeth to have healthy crowns, or with restorations no more than 2 mm in diameter and no clinical and radiographical signs or symptoms of pulp or periapical inflammatory changes. The negative control group consisted of 10 root filled teeth. Measurements were first taken from the index finger of patients. Their teeth were then subjected to a thermal test with refrigerant gas and then to a vitality test with pulse oximetry. Data were analysed by Pearson`s and paired t-tests. Results There were no significant statistical correlations between blood oxygen levels in the index finger and in the teeth of the patient (P > 0.05). There was a statistically significant difference in the oxygen levels between the two tooth groups studied and the index finger (P <= 0.002). Mean oxygen values in the index finger of patients were 95% (SD = 1.6), oxygen values in the maxillary central incisor were 91.29% (SD = 2.61) and mean oxygen values in maxillary canine were 90.69% (SD = 2.71). Conclusion The method determined consistently the level of blood oxygen saturation of the pulp in maxillary central incisor and canine teeth and can therefore be used for pulp vitality testing. Further studies are required to assess the effectiveness and validity of pulse oximetry in determining pulp vitality in traumatized teeth.

WNT-5A, but not matrix metalloproteinase 3 or beta-catenin protein, expression is related to early stages of lip carcinogenesis

Background: Oncogenic Wnt/beta-catenin signaling occurs in numerous types of cancers, but little is known about the role of the Wnt protein family member, WNT-5A, in lip carcinogenesis. The aim of this study was to investigate WNT-5A, beta-catenin, and matrix metalloproteinase (MMP)-3 protein expression in actinic cheilitis (AC), and lip squamous cell carcinoma (LSCC). Methods: Twenty-one cases of AC, and fifty-one cases of LSCC were analyzed, with normal lip mucosa used as a control. Qualitative and semi-quantitative analyses of WNT-5A, beta-catenin, and MMP-3 immunostaining pattern and cellular distribution were performed. Results: WNT-5A was observed in more than 50% of the cells, scattered in all layers of AC, in contrast to the absence of immunostaining in normal lip mucosa. AC presented a higher level of WNT-5A expression than LSCC (P = 0.0289, Fisher test), while MMP-3 immunoexpression was statistically more significant in LSCC than in AC (P = 0.0285, Fisher test). Immunolabeling of beta-catenin protein was differentially distributed between samples; the majority of AC cases (61.90%) demonstrated a membranous-cytoplasmic pattern, while a considerable number of LSCC cases (29.41%) revealed a cytoplasmic pattern, instead of the usual membranous pattern. Conclusions: The present results suggest that WNT-5A may be an important marker during initial events of AC malignant transformation, in which non-canonical and canonical Wnt/beta-catenin signaling pathways could be involved. Additionally, WNT-5A might recruit other events in LSCC, such as MMP-3 protein synthesis, as its presence is increased in established malignant processes without beta-catenin dependency.

Effect of argon purity on mechanical properties, microstructure and fracture mode of commercially pure (cp) Ti and Ti-6Al-4V alloys for ceramometal dental prostheses

Provision of an inert gas atmosphere with high-purity argon gas is recommended for preventing titanium castings from contamination although the effects of the level of argon purity on the mechanical properties and the clinical performance of Ti castings have not yet been investigated. The purpose of this study was to evaluate the effect of argon purity on the mechanical properties and microstructure of commercially pure (cp) Ti and Ti-6Al-4V alloys. The castings were made using either high-purity and/or industrial argon gas. The ultimate tensile strength (UTS), proportional limit (PL), elongation (EL) and microhardness (VHN) at different depths were evaluated. The microstructure of the alloys was also revealed and the fracture mode was analyzed by scanning electron microscopy. The data from the mechanical tests and hardness were subjected to a two-and three-way ANOVA and Tukey`s test (alpha = 0.05). The mean values of mechanical properties were not affected by the argon gas purity. Higher UTS, PL and VHN, and lower EL were observed for Ti-6Al-4V. The microhardness was not influenced by the argon gas purity. The industrial argon gas can be used to cast cp Ti and Ti-6Al-4V.

Influence of Photoactivation Protocol and Light Guide Distance on Conversion and Microleakage of Composite Restorations

Purpose: To evaluate the effect of light guide distance and the different photoactivation methods on the degree of conversion (DC) and microleakage of a composite. Methods and Materials: Three photoactivation protocols (600mW/cm(2) x 40 seconds; 400 mW/cm(2) x 60 seconds or 200 mW/cm(2) x 20 seconds, followed by 500 mW/cm(2) X 40 seconds) and three distances from the light source (0, 3 or 7 mm) were tested. Cylindrical specimens (5 nun diameter; 2 mm tall; n=3) were prepared for the DC test (FT-Raman). Class V cavities were made in 90 bovine incisors to conduct the microleakage test. The specimens were conditioned for 15 seconds with phosphoric acid (37%), followed by application of the adhesive system Prime & Bond NT (Dentsply/Caulk). The preparations were restored in bulk. The specimens were stored for 24 hours in distilled water (37 degrees C) before being submitted to the silvernitrate microleakage protocol. The restorations were sectioned and analyzed under 25x magnification. Results: Statistical analyses (two-way ANOVAs and Tukey test, alpha=0.05) found significance only for the factor distance (p=0.015) at the top of the composite for the DC test. Conversion was statistically lower for the 7 mm groups compared to the 0 and 3 mm groups, which were equivalent to each other. At the bottom of the specimens, none of the factors or interactions was significant (p<0.05). The Kruskal-Wallis test showed that, in general, the soft-start method led to lower microleakage scores when compared to the continuous modes, mainly when associated with a distancing of 7 mm (p<0.01). With the exception of specimens irradiated with 400mW/cm(2) that did not demonstrate variations on scores for the distances tested, higher microleakage was observed for shorter distances from the light source. Conclusions: Soft-start methods may reduce microleakage when the light guide distancing provides a low level of irradiance, which also causes a discrete reduction in the DC.

Understanding the impact of divalent cation substitution on hydroxyapatite: An in vitro multiparametric study on biocompatibility

Hydroxyapatite (HA), a stable and biocompatible material for bone tissue therapy, may present a variable stoichiometry and accept a large number of cationic substitutions. Such substitutions may modify the chemical activity of HA surface, with possible impact on biocompatibility. In this work, we assessed the effects of calcium substitution with diverse divalent cations (Pb(2+), Sr(2+), Co(2+), Zn(2+), Fe(2+), Cu(2+), or Mg(2+)) on the biological behavior of HA. Physicochemical analyses revealed that apatite characteristics related to crystallinity and calcium dissolution/uptake rates are very sensitive to the nature of cationic substitution. Cytocompatibility was evaluated by mitochondrial activity, membrane integrity, cell density, proapoptotic potential, and adhesion tests. With the exception of Zn-HA, all the substituted HAs induced some level of apoptosis. The highest apoptosis levels were observed for Mg-HA and Co-HA. Cu-HA was the only material to impair simultaneously mitochondrial activity, membrane integrity, and cell density. The highest relative cell densities after exposure to the modified HAs were observed for Mg-HA and Zn-HA, while Co-HA significantly improved cell adhesion onto HA surface. These results show that changes on surface dissolution caused by cationic substitution, as well as the increase of metal species released to biological media, were the main responsible factors related to alterations on HA biocompatibility. (C) 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 98A: 351-358, 2011.

Prevalence of dental wear among 12-year-old Brazilian adolescents using a modification of the tooth wear index

Objective. This study investigated the prevalence of dental wear in 12-year-old adolescents using a modification of the tooth wear index (TWI). The modifications were proposed in order to fit with the World Health Organization standard, thus allowing application of the index in broad epidemiological surveys. Study design: An epidemiological cross-sectional survey was performed by trained, calibrated examiners, using a modified version of the TWI. Methods: Urban elementary schools were chosen because they provide a fair representation of the city`s population in terms of socio-economic status. The sample included 295 adolescents, selected randomly and systematically. Dental wear was assessed by calibrated examiners (kappa > 0.85), using a modified version of the TWI. This modified version includes a code for teeth restored due to wear, and another code for teeth that cannot be assessed. In addition, it does not differentiate the depth of dentine involvement. Proportions and confidence intervals were used to describe the prevalence of dental wear. Mann-Whitney test was used to detect differences in the degree of dental wear between mates and females. The level of statistical significance was set at 5%. Results: In total, 24,780 dental surfaces were evaluated. Among these surfaces, 73.10% did not present dental wear, 24.10% had incipient lesions, 2.46% had moderate lesions and 0.34% had been restored. No severe lesions were detected. Tooth wear was mainly seen on the occlusal/incisal surfaces (26.55%), involving enamel or enamel-dentine, but not the secondary dentine or pulp. The prevalence of dental wear was 26.90%. Considering the different teeth, wear was present in 53.22% of incisors, 50.51% of canines, 10.17% of premolars and 10.85% of molars. The prevalence of the different degrees of dental wear was similar in mates and females (P > 0.05). Conclusion: The modified TWI seems to bean effective toot for use in broad epidemiological surveys, due to easier calibration and high reproducibility rates. (C) 2008 The Royal Institute of Public Health. Published by Elsevier Ltd. All rights reserved.

Influence of Calcium Hydroxide Association on the Physical Properties of AH Plus

Introduction: This study evaluated in vitro the radiopacity, setting time, flow, film thickness, solubility, and dimensional changes of AH Plus sealer pure (Dentsply De Trey Gmbh, Konstanz, Germany) and containing 5% and 10% of calcium hydroxide. Methods: The study was performed according to the requirements of the ISO 6876:2001 standard and the American National Standards Institute/American Dental Association (ANSI/ADA)`s Specification No. 57. The following tests were performed: setting time, flow, film thickness, dimensional stability, radiopacity, and solubility. Data were analyzed statistically by analysis of variance and the Tukey tests with a significance level of 5%. Results: The addition of 5% or 10% calcium hydroxide to AH Plus sealer did not alter significantly the radiopacity or setting time values (p > 0.05). Adding 10% calcium hydroxide reduced the flow compared with pure AH Plus and AH Plus/5% calcium hydroxide. The addition of 5% and 10% calcium hydroxide increased the solubility and expansion of AH Plus. All materials presented expansion valued above those recommended by the ADA. The addition of calcium hydroxide to the sealer resulted in greater film thickness. Conclusions: The addition of 5% calcium hydroxide did not affect most physical properties of AH Plus sealer. (J Endod 2010;36:1048-1051)

Evaluation of the radiopacity of some commercial and experimental root-end filling materials

Objective. The aim of the present study was to evaluate the radiopacity of 5 root end filling materials (white MTA Angelus, MTA Bio, light-cured MTA, Sealepox RP, and Portland cement clinker with bismuth oxide and calcium sulfate). Method. Five specimens, 10 mm in diameter and 1 mm in thickness according to specification ISO 6876: 2001 were fabricated from each material and radiographed using Insigth occlusal films close to a graduated aluminum step-wedge (2 to 16 mm in thickness). Radiographs were digitized and compared to the aluminum step-wedge. The radiographic density data were converted into millimeters of aluminum (mm Al), using the Digora 1.51 software. Results were evaluated statistically using the analysis of variance (ANOVA) followed by Tukey test. The level of significance was set at 5% (P<.05%). Results. Radiopacity values ranged from 1.21 mm Al (light-cured MTA) to 6.45 mm Al (MTA Angelus). Comparison between materials showed significant difference (P<.05) between MTA Angelus and all other materials, between Sealepox RP and MTA Bio, and between light-cured MTA and Portland cement clinker. Light-cured MTA was significantly less radiopaque than all other materials. No significant difference (P>.05) was found between MTA Bio and Portland cement clinker. Conclusions. All retrograde filling materials evaluated showed greater radiopacity than dentin. All the materials, except light-cured MTA met the minimum radiopacity standards of 3 mm Al recognized by the ISO 6876: 2001 and ADA n.57. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009; 108: e35-e38)

Effects of Mandibular Fixed Implant-Supported Prostheses on Masticatory and Swallowing Functions in Completely Edentulous Elderly Individuals

To evaluate the effect of oral rehabilitation with immediately loaded fixed implant-supported mandibular prostheses on chewing and swallowing in elderly individuals. Materials and Methods: Fifteen completely edentulous patients aged more than 60 years (10 women and five men), wearing removable dentures in both arches, had a mandibular denture replaced by an implant-supported prosthesis. All individuals were evaluated before surgery and again 3, 6, and 18 months later with regard to mastication and swallowing conditions. Examinations entailed an interview, evaluation of tactile sensitivity of the face, and observation of food intake, masticatory type, formations of bolus, and pain during mastication. The swallowing evaluation comprised observation of clinical signs related to the oral and pharyngeal stages of swallowing, as well as the presence of oral residue. The findings of different evaluations before and 3, 6, and 18 months after the surgical-prosthetic procedure were statistically compared by analysis of variance for repeated measurements at a significance level of 5%. Results: The questionnaire revealed a reduction in complaints of masticatory and swallowing disturbances, a decreased need for liquid ingestion, and reduced choking and coughing. Clinical evaluations showed improved oral function and bolus propulsion for both solid and paste-consistency foods; pain during mastication was also resolved. Conclusion: Treatment with mandibular implant-supported dentures had positive effects on the clinical aspects of mastication and swallowing in elderly individuals. INT J ORAL MAXILLOFAC IMPLANTS 2009; 24:110-117

Influence of Dental Plaque on Human Enamel Erosion: In Situ/Ex Vivo Study

Purpose: The objective of the present in situ study was to evaluate the influence of dental plaque on human enamel erosion. Materials and Methods: Thirteen volunteers wore acrylic palatal devices with four enamel specimens that were prepared from freshly extracted impacted human third permanent molars (4 x 4 mm), randomly selected and distributed into two vertical rows, corresponding to the following groups: GI, erosion of dental plaque-free samples, and GII, erosion of dental plaque-covered samples. For the formation of dental plaque, the specimens were placed 1 mm below the level of the appliance and covered with a plastic mesh to allow the accumulation of dental plaque. The palatal device was continuously worn by the volunteers for 14 consecutive days and then immersed in a soft drink (Coca-Cola (R), 150 ml) for 5 min, three times a day. Half of the surfaces of specimens were coated with nail varnish for profilometry tests. The study variables included the depth of enamel surface wear (profilometer, vertical ranges in pm) and the percentage of superficial microhardness change (%SMHC). Data were analysed using the t test (P < 0.05). Results: The %SMHC and depth of enamel surface wear were significantly higher for GI (-87.82% +/- 3.66 and 4.70 mu m +/- 1.65) than for GII (-13.79% +/- 4.22 and 0.14 mu m +/- 0.03). Conclusions: It was concluded that the dental plaque formed in situ was able to protect the enamel surface against erosion by a cola soft drink, thus reducing the depth of enamel surface wear and the %SMHC.

Cytotoxicity of resin-based light-cured liners

Purpose: To evaluate the cytotoxic effects of resin-based light-cured liners on culture of pulp cells. Methods: Discs measuring 4 mill in diameter and 2 mm thick were fabricated from TheraCal (TCMTA), Vitrebond (VIT), and Ultrablend Plus (UBP). These specimens were immersed in serum-free culture medium (DMEM) for 24 hours or 7 days to produce the extracts. After incubating the pulp cells for 72 hours, the extracts were applied on the cells and the cytotoxic effects were determined based on the cell metabolism (MTT), total protein expression and cell morphology (SEM). In the control group, fresh DMEM was used. Data from MTT analysis and protein expression were submitted to Kruskal-Wallis and Mann-Whitney tests at the preset level of significance of 5%. Results: When in contact with the 24-hour extract, TCMTA, VIT, and UBP decreased the cell metabolism by 31.5%, 73.5% and 71.0%, respectively. The total protein expressed by the cells in contact with VIT and UBP was lower than TCMTA and DMEM (Mann-Whitney, P< 0.05). When in contact with the 7-day extract, TCMTA, VIT, and UBP decreased the metabolic activity by 45.9%, 77.1% and 64.4%, respectively. All the liners expressed statistically lower amounts of proteins when compared to the control. A reduction in the number of cells was observed for all liners. The remaining cells from TCMTA group resembled those from the control group while for VIT and UBP the cells presented significant morphological alterations. (Ani J Dent 2009;22:137-142).

Mechanical Testing of Indirect Composite Materials Directly Applied on Implant Abutments

Purpose: To test the strength to failure and fracture mode of three indirect composite materials directly applied onto Ti-6Al-4V implant abutments vs cemented standard porcelain-fused-to-metal (PFM) crowns. Materials and Methods: Sixty-four locking taper abutments were randomly allocated to four groups and were cleaned in ethanol in an ultrasonic bath for 5 min. After drying under ambient conditions, the abutments were grit blasted and a custom 4-cusp molar crown mold was utilized to produce identical crowns (n = 16 per group) of Tescera (Bisco), Ceramage (Shofu), and Diamond Crown (DRM) according to the manufacturer`s instructions. The porcelain-fused-to-metal crowns were fabricated by conventional means involving the construction and a wax pattern and casting of a metallic coping followed by sintering of increasing layers of porcelain. All crowns were loaded to failure by an indenter placed at one of the cusp tips at a 1 mm/min rate. Subsequently, fracture analysis was performed by means of stereomicroscopy and scanning electron microscopy. One-way ANOVA at 95% level of significance was utilized for statistical analysis. Results: The single load to failure (+/- SD) results were: Tescera (1130 +/- 239 N), Ceramage (1099 +/- 257 N), Diamond Crown (1155 +/- 284 N), and PFM (1081 +/- 243 N). Stereomicroscopy analysis showed two distinct failure modes, where the loaded cusp failed either with or without abutment/metallic coping exposure. SEM analysis of the fractures showed multiple crack propagation towards the cervical region of the crown below a region of plastic deformation at the indenter contact region. Conclusion: The three indirect composites and PFM systems fractured at loads higher than those typically associated with normal occlusal function. Although each material had a different composition and handling technique, no significant differences were found concerning their single load to fracture resistance among composite systems and PFM.

Evaluation of distances between the mandibular teeth and the alveolar process in Brazilians with normal occlusion

Introduction: The aims of this study were to evaluate the distances between the mandibular permanent teeth and the alveolar process in Brazilians with normal occlusion and to compare them with normal American values. Methods: We used 59 mandibular casts from untreated subjects who had permanent dentition and the 6 keys to normal occlusion. A computer program was used to calculate the distances between the dental reference points and the alveolar process for each tooth. The mean values were then compared to the normal values by applying the Student t test at a significance level of 0.05. Results: The results showed a progressive increase of these distances from the anterior region (incisors) to the posterior region (molars), from 0.00 to 2.49 mm. All measurements had statistically significant differences from the American sample, except for the values for canines and first premolars. Conclusions: Brazilians with normal occlusion have more lingual crown positions for the incisors, second premolars, and molars compared with Americans with normal occlusion. Although these findings were statistically significant, they are unlikely to be clinically significant. (Am J Orthod Dentofacial Orthop 2010; 137: 308.e1-308.e4)

COX-2 inhibition decreases VEGF expression and alveolar bone loss during the progression of experimental periodontitis in rats

Background: Vascular endothelial growth factor (VEGF) is a macromolecule of importance in inflammation that has been implicated in periodontitis. The aims of this study were to investigate VEGF expression during the progression of periodontal disease and to evaluate the effect of a preferential cyclooxygenase (COX)-2 inhibitor meloxicam on VEGF expression and alveolar bone loss in experimentally induced periodontitis. Methods: A total of 120 Wistar rats were randomly separated into groups 1 (control) and 2 (meloxicam, 3 mg/kg/day, intraperitoneally, for 3, 7, 14, or 30 days). Silk ligatures were placed at the gingival margin level of the lower right first molar of all rats. VEGF expression was assessed by reverse transcription-polymerase chain reaction (RT-PCR), Western blot (WB), and immunohistochemical (IHC) analyses. The hemiarcades were processed for histopathologic analysis. RT-PCR and WB results were submitted to analysis of variance, the Tukey test, and Pearson correlation analysis (P<0.05). Results: A reduction in alveolar bone resorption was observed in the meloxicam-treated group compared to the control group at all periods studied. There was a positive correlation between COX-2 mRNA and VEGF mRNA in the gingival tissues and periodontal disease (R = 0.80; P = 0.026). Meloxicam significantly reduced the increased mRNA VEGF expression in diseased tissues after 14 days of treatment (P = 0.023). Some alterations in VEGF receptor I mRNA expression were observed, but these were not statistically significant. VEGF protein expression in WB experiments was significantly higher in diseased sites compared to healthy sites (P<0.05). After 14 days of treatment with meloxicam, an important decrease in VEGF protein expression was detected in diseased tissues (P = 0.08). Qualitative IHC analysis revealed that VEGF protein expression was higher in diseased tissues and decreased in tissues from rats treated with meloxicam. Conclusions: The present data suggest an important role for VEGF in the progression of periodontal disease. Systemic therapy with meloxicam can modify the progression of experimentally induced periodontitis in rats by reducing VEGF expression and alveolar bone loss.