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Acta Odontol Scand [journal]
- In vitro evaluation of variances between real and declared concentration of hydrogen peroxide in various tooth-whitening products. [JOURNAL ARTICLE]
- Acta Odontol Scand 2014 Oct 24.:1-4.
Abstract Objectives. The aim of this in vitro study was to analyze the real hydrogen peroxide (HP) concentration in various commercially available tooth-whitening products containing HP and/or carbamide peroxide (CP). Materials and methods. Sixteen commercially available tooth-whitening products containing various concentrations of CP or HP were investigated. The products were divided into four groups: dentist-supervised home bleaching products (Group 1, n = 5), in-office bleaching products (Group 2, n = 4), over-the-counter bleaching products (Group 3, n = 3) and whitening toothpastes and rinses (Group 4, n = 4). The peroxide concentration was determined using the oxy-reduction titration method. All the reagents used in the study were of analytic grade and freshly prepared before the experiment. Results. The HP concentration in various dentist-supervised home bleaching products and in-office bleaching products ranged from 3.02-37.08% (expected range = 3-38%). The HP concentration of over-the-counter whitening products ranged from 1.24-5.57% (expected range cannot be estimated as no concentration of active ingredient was provided). Among whitening toothpastes and rinses, Colgate Plax whitening rinse showed more than 1% HP concentration, whereas it was lower than 0.05% in other whitening toothpastes and oral rinses (expected range cannot be estimated as no active ingredient was mentioned). Conclusions. HP concentration of most of the professional tooth-whitening products was different from the expected concentrations, although the deviations were small and most of the products were close to the expected concentration. No concentration of active ingredient was provided for over-the-counter whitening products and no active ingredient was mentioned for whitening toothpastes and rinses.
- Effects of dentin surface treatments including Er,Cr:YSGG laser irradiation with different intensities on the push-out bond strength of the glass fiber posts to root dentin. [JOURNAL ARTICLE]
- Acta Odontol Scand 2014 Oct 20.:1-7.
Abstract Objective. Intra-canal post systems are commonly used to restore root-filled teeth. Bond strengths of the posts can be affected by various surface treatments of the post or the dentin. The aim of this study was to evaluate the effects of dentin surface treatments including erbium-chromium; yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser irradiation with different intensities on the push-out bond strength of the glass fiber posts to root dentin. Materials and methods. Forty single-rooted human maxillary incisors were filled and post spaces were prepared. After these procedures, the specimens were divided randomly into four groups according to the dentin surface treatments, as follows: (i) untreated surface (control), (ii) 1W Er,Cr:YSGG laser application, (iii) 2W Er,Cr:YSGG laser application and (iv) 3W Er,Cr:YSGG laser application. Then the posts were cemented into the root canals using dual-cured resin cement. Bonded specimens were cut into 1-mm-thick slices and push-out tests were performed using a universal testing device. All specimens were loaded until fracture and the failure modes were evaluated with a stereomicroscope at 32× magnification. Representative specimens were analyzed by scanning electron microscopy. Data were analyzed using a one-way ANOVA, Tukey and Wilcoxon tests. Results. The bond strength values ranged from 3.22-4.68 MPa. There were no statistically significant differences among the groups, regardless of the different levels. The coronal and middle levels of the post space had significantly higher bond strength values compared with the apical level (p < 0.05). Conclusion. Er,Cr:YSGG laser irradiation with different intensities did not increase the bond strength of the fiber posts to the root canal dentin walls.
- Comparing the influence of crestal cortical bone and sinus floor cortical bone in posterior maxilla bi-cortical dental implantation: A three-dimensional finite element analysis. [JOURNAL ARTICLE]
- Acta Odontol Scand 2014 Oct 20.:1-9.
Abstract Objective. This study aimed to compare the influence of alveolar ridge cortical bone and sinus floor cortical bone in sinus areabi-cortical dental implantation by means of 3D finite element analysis. Materials and methods. Three-dimensional finite element (FE) models in a posterior maxillary region with sinus membrane and the same height of alveolar ridge of 10 mm were generated according to the anatomical data of the sinus area. They were either with fixed thickness of crestal cortical bone and variable thickness of sinus floor cortical bone or vice versa. Ten models were assumed to be under immediate loading or conventional loading. The standard implant model based on the Nobel Biocare implant system was created via computer-aided design software. All materials were assumed to be isotropic and linearly elastic. An inclined force of 129 N was applied. Results. Von Mises stress mainly concentrated on the surface of crestal cortical bone around the implant neck. For all the models, both the axial and buccolingual resonance frequencies of conventional loading were higher than those of immediate loading; however, the difference is less than 5%. Conclusion. The results showed that bi-cortical implant in sinus area increased the stability of the implant, especially for immediately loading implantation. The thickness of both crestal cortical bone and sinus floor cortical bone influenced implant micromotion and stress distribution; however, crestal cortical bone may be more important than sinus floor cortical bone.
- Structural equation modeling to assess gender differences in the relationship between psychological symptoms and dental visits after dental check-ups for university students. [JOURNAL ARTICLE]
- Acta Odontol Scand 2014 Oct 20.:1-7.
Abstract Objective. Some studies have shown a relationship between psychological symptoms and oral health behaviors. However, it is unknown whether gender differences affect the relationship between psychological symptoms and oral health behaviors. In addition, gender differences in the relationship between dental anxiety and dental visits for treatment or regular check-up are unclear. The objective of the present study was to explain the relationships among gender differences, psychological symptoms, oral health behaviors, dental anxiety and 'expectation of dental visit', evaluated as 'dental visits when treatments are recommended' in university students. Materials and methods. A total of 607 students (311 males, 296 females) aged 18-38 years old were examined. The information was collected via questionnaire regarding gender, psychological symptoms and oral health behaviors. Psychological symptoms were assessed using the Hopkins Symptom Checklist. Structural equation modeling was used to test pathways from these factors to 'expectation of dental visit'. Multiple-group modeling was also conducted to test for gender differences. Results. Psychological symptoms were related to low expectation of dental visit in females, but there was no such relationship in males. Oral health behaviors were related to expectation of dental visit in both genders. Conclusions. Psychological symptoms were directly related to expectation of dental visit in females and oral health behaviors were related to expectation of dental visit in both genders. To promote dental visits after dental check-ups at school, it might be necessary to improve oral health behaviors in both genders and to evaluate psychological symptoms, especially in females.
- Changes in the location of the human mandibular foramen as a function of growth and vertical facial type. [JOURNAL ARTICLE]
- Acta Odontol Scand 2014 Oct 20.:1-5.
Abstract Objective. A previous cross-sectional investigation showed that the mandibular foramen location depends on the age and the vertical facial pattern of growing individuals. The aim of the present longitudinal study was to explain how these factors influence the distance between the foramen and the occlusal plane. It is known that a certain distance is necessary for a successful inferior alveolar nerve block in clinical dentistry. Materials and methods. This distance, as well as another four cephalometric variables, were measured on both pre-treatment and 10-year post-treatment lateral cephalometric radiographs collected from 50 patients who underwent orthodontic treatment. The changes between these two sets of measurements were also calculated. Results. A multiple regression analysis was performed using the pre-treatment age, the pre-treatment inter-maxillary angle, the rotation of the occlusal plane and the change in mandibular ramus height as independent variables and the change of foramen-occlusal plane distance as a dependent variable. The independent variables under investigation were found to account for more than half of the variability of the foramen-occlusal plane distance (r = 0.732; p < 0.001). Conclusion. In very young individuals the mandibular foramen is located approximately at the level of the occlusal plane. With age it moves upwards relative to the occlusal plane and more so for those individuals with a low anterior facial height (short-face vertical facial type). These observations are, at least, partially explained by the differential growth of the various elements of the maxillo-mandibular complex and the change of the inclination of the occlusal plane.
- Influence of successive light-activation on degree of conversion and knoop hardness of the first layered composite increment. [JOURNAL ARTICLE]
- Acta Odontol Scand 2014 Oct 14.:1-6.
Abstract Purpose: To evaluate the influence of light-activation of second, third and fourth increments on degree of conversion (DC) and microhardness (KHN) of the top (T) and bottom (B) surface of the first increment. Materials and methods. Forty samples (n = 5) were prepared. In groups 1-4, after each increment light-activation (multiple irradiation), T and B of the first increment were measured in DC and KHN. In groups 5-8, only the first increment was made (single irradiation) and measurements of DC and KHN were taken at 15 min intervals. The light-activation modes were (XL) 500 mW/cm(2) × 38 s (G1/G5); (S) 1000 mW/cm(2) × 19 s (G2/G6), (HP) 1400 mW/cm(2) × 14 s (G3/G7); (PE) 3200 mW/cm(2) × 6 s (G4/G8). Data for DC and KHN were analyzed separately by using PROC MIXED for repeated measures and Tukey-Kramer test (α = 0.05). Results. For KHN, B showed lower values than T. PE resulted in lower values of KHN in B surface. For single and multiple irradiations, T and B of first measurement showed the lowest KHN and the fourth measurement showed the highest, with significant difference between them. For single irradiation, first and second increments presented similar KHN, different from the third and fourth increment, which did not differ between them. For multiple irradiations, the second light-activation resulted in KHN similar to first, third and fourth increments. For DC, except QTH, T presented higher DC than B. Conclusion. The light-activation of successive increments was not able to influence the KHN and DC of the first increment.
- Applicability of the Demirjian method for dental age estimation in western Turkish children. [JOURNAL ARTICLE]
- Acta Odontol Scand 2014 Oct 14.:1-5.
Abstract Objective. The aim of this study was to examine whether the Demirjian method would be appropriate for estimation of the dental age of western Turkish children. Materials and methods. This study comprised 635 Turkish children (age = 7-16 years) from the western Aegean region who were chosen on the basis of radiological evidence from digital orthopantomograms. Their dental maturity was evaluated according to the stages proposed by Demirjian. A paired t-test was used for statistical analysis. Results. The mean difference between the chronological and dental ages ranged from 0.10-0.76 years for males and from 0.28-0.87 years for females. Conclusion. The applicability of the Demirjian method is not suitable for western Turkish children and western Turkish children have a lower degree of dental maturity than that observed in the eastern, northeastern and northern Turkish subjects.
- Normative and self-perceived orthodontic treatment need in Nigerian school children. [JOURNAL ARTICLE]
- Acta Odontol Scand 2014 Oct 14.:1-4.
Abstract Objective. The aim of this study was to assess the normative and self-perceived need for orthodontic treatment in Nigerian children, and to evaluate distribution of orthodontic treatment need according to gender and age. Materials and methods. The sample consisted of 441 randomly selected school children, aged 11-18 years in Benin City, Nigeria. The subjects were further sub-grouped according to gender (229 males and 212 females) and age (246 11-13 years old and 195 14-18 years old). The Dental health Component (DHC) and Aesthetic Component (AC) of Index of Orthodontic Treatment Need (IOTN) were used to assess orthodontic treatment need normatively. Self-perceived need was evaluated by asking the subjects to rate their dental aesthetics on the Aesthetic Component scale of IOTN. Chi-square tests were used to evaluate gender and age differences in distribution of treatment need. Results. A definite need for orthodontic treatment was found among 21.5% (grades 4-5 of DHC) and 6.3% (grades 8-10 of AC) of the subjects; 3.9% of the subjects perceived a definite need for orthodontic treatment (grades 8-10 of AC). There were no statistically significant gender and age differences in distribution of orthodontic treatment need among the subjects (p > 0.05). Conclusion. The study revealed a need for orthodontic treatment in slightly more than one fifth (21.5%) of this sample of Nigerian children. The sample population has a lower need on aesthetic grounds and their normative and self-perceived orthodontic treatment needs were not influenced by gender and age.
- A comparison of the fitting accuracy of thermoplastic denture base resins used in non-metal clasp dentures to a conventional heat-cured acrylic resin. [JOURNAL ARTICLE]
- Acta Odontol Scand 2014 Oct 14.:1-5.
Abstract Objective. To incorporate a metal framework into removable partial dentures, the dimensional accuracy of thermoplastic resins requires precision equivalent to conventional acrylic resins. This study aimed to evaluate the fitting accuracy of thermoplastic resins compared to heat-cured acrylic resin. Materials and methods. Four thermoplastic resins (polyethylene terephthalate [EstheShot, ES; EstheShot Bright, ES-B], polyamide [Lucitone FRS, LF], polycarbonate [Reigning Resin N, RN] and a heat-curing acrylic resin [Acron, AC]) were used. The specimens were created on master casts constructed of high-strength stone that simulated a maxillary edentulous ridge. Additionally, high-expansion stone was used as the master cast for RN specimens. The ES-B, LF and RN specimens were prepared with and without annealing after injection molding. The gaps between the molded resin and the cast were measured. Results. ES had the smallest gap and was significantly smaller than AC (p < 0.05). The gap sizes of ES-B, LF and RN (high-expansion stone) without annealing were similar to AC (p > 0.05), while the gap size of RN (high-strength stone) with and without annealing was significantly greater than AC (p < 0.001). The gap sizes of ES-B and LF with annealing were significantly less than AC (p < 0.05). Further, the gap sizes of ES-B, LF and RN with annealing were significantly smaller than the gaps without annealing (p < 0.05). Conclusions. The results suggested that ES, ES-B and LF have adequate fitting accuracy for incorporating metal framework into dentures and that annealing effectively improved the fitting accuracy of ES-B, LF and RN.
- Influence of preparation design on fit and ceramic thickness of CEREC 3 partial ceramic crowns after cementation. [JOURNAL ARTICLE]
- Acta Odontol Scand 2014 Oct 9.:1-7.
Abstract Objective. This study investigated the influence of preparation design on the marginal and internal gap and ceramic thickness of partial ceramic crowns (PCCs) fabricated with the CEREC 3 system. Materials and methods. Sixteen extracted human mandibular molars were prepared according to two different preparation designs (n = 8): a retentive preparation design with traditional cusp capping (Group I) and a non-retentive preparation design with horizontal reduction of cusps (Group II). PCCs were fabricated from IPS Empress CAD with the CEREC 3 system. The parameters for luting space and minimum occlusal ceramic thickness were set to 30 μm and 1.5 mm, respectively. The fabricated PCCs were cemented to their corresponding teeth with self-adhesive resin cement and were then scanned by micro-computed tomography. The marginal and internal gaps were measured at pre-determined measuring points in five bucco-lingual and three mesio-distal cross-sectional images. The ceramic thicknesses of the PCCs were measured at the measuring points for cusp capping areas. Results. Group II (167.4 ± 76.4 μm) had a smaller overall mean gap, which included the marginal and internal gap measurements, than that of Group I (184.8 ± 89.0 μm). The internal gaps were larger than the marginal gaps, regardless of preparation design. Group I presented a thinner ceramic thickness in the cusp capping areas than the minimum occlusal ceramic thickness parameter of 1.5 mm. Conclusion. Preparation design had an influence on fit, particularly the internal gap of the PCCs. Ceramic thickness could be thinner than the minimum ceramic thickness parameter.