Search

Statement of Problem: Bioglasses are a series of biocompatible dental materials, which are considered as light conducting inserts in resin composite restorations. Consequently, their chemical stability is more essential when they are used in conjunction with resin composite. Objectives: The aim of this study was to evaluate and compare the chemical stability of Bioglass with dental porcelain and resin composite by determining the amount of released K+, Na+, Ca2+ ions and silicone elements from these materials as a result of exposure to tested solutions with different pH levels including: Sodium Bicarbonate [SB, (pH=9.2)], Sodium Buffer Lactate [SBL, (pH=2.4)], Acetic Acid [AA, (pH=2.4)], and Distilled Water [DW, (pH=6.2)]. Materials and Methods: In this experimental study, forty 2.0 × 4.0 cylindrical rods for each tested material group (Dental porcelain, Resin composite and Bioglass) were prepared. They were divided into four subgroups of 10 rods each, which immersed in one of the four testing solutions in a designated container. The containers were stored at 50°C and 100% humidity for one week. The released ions were measured by using a spectrophotometer (µg/cm2/ml). The data were statistically analyzed by nonparametric Kruskal-Wallis H test. Results: It was observed that the tested materials released ions at different levels of concentration. The significant amounts of Sodium, Calcium, and Silicon ions release were measured in Bioglass subgroups in all the tested solutions (p < 0.001). Potassium ion release from dental porcelain was the largest in all solutions except for AA in which Bioglass had the greatest potassium ion release (p < 0.001). Conclusions: A greater structural instability was observed for Biogalss group than dental porcelain and resin composite in testing solutions with different pH .levels

Aim: To examine the effect of reduction in MTA particle size on dento-alveolar and osseous healing in dogs., Methodology: Root canals of 24 mandibular premolars in four 2-year-old beagles were prepared and filled with gutta-percha and sealer. Two to four weeks later, during periapical surgery, the root-end cavity preparations in these teeth were filled with either grey ProRoot MTA or modified (reduced particle sizes with faster setting time) MTA. The animals were sacrificed 4 months later. Degrees of inflammation, type of inflammatory cells, fibrous connective tissue adjacent to the root-end filling materials, cementum formation over the resected roots and root-end filling materials and bone healing were examined. Data were analysed using the McNemar test., Results: No significant differences in healing of periapical tissues were found when comparing ProRoot MTA to a modified MTA containing reduced particle sizes., Conclusion: Reducing the particle sizes of MTA did not impact its biological properties., (© 2016 International Endodontic Journal. Published by John Wiley & Sons Ltd.)

Aim: The aim of this prospective cohort study was to evaluate the postinsertion posterior single-implant occlusion changes at 3- and 6-month intervals using T-Scan computerized occlusal analysis., Materials and Methods: A total of 21 patients received single implant, opposed by natural dentition, in posterior regions of the maxilla or mandible (13 premolar, 8 molar) and were finally restored with cemented-retained metal-ceramic crowns. The occlusal contacts were equilibrated according to the implant-protective occlusion concept to develop light contact with heavy occlusion and no contact with light occlusion in maximum inter-cuspation. The percentage of force applied to the implant crowns (POFI) and contralateral teeth (POFT) was evaluated using T-Scan computerized occlusal analysis at prosthesis insertion, 3- and 6-month follow-up appointments. The data were statistically analyzed using Friedman test and Wilcoxon post hoc test (α = 0.05)., Results: The POFI values at the 6- and 3-month follow-up appointments were significantly higher than those at prostheses insertion (p = 0.001 and p = 0.005 respectively). In addition, there were significant differences between the POFI at 3- and 6-month follow-up (p = 0.020). However, the POFT values at 3- and 6-month follow-up appointments were significantly lower than those at baseline (p < 0.001)., Conclusion: The intensity of occlusal contacts of implant-supported prostheses opposed by natural dentition gradually increased after prosthesis insertion. Placement of single posterior implant-supported restoration decreased the percentage of occlusal force applied to contralateral arch., Clinical Significance: A periodic occlusal adjustment of implant-supported prostheses is necessary to prevent potential overloading from the movement of opposing natural dentition.

Statement of the Problem: Similar to conventional amalgam, high-copper amalgam alloy may also undergo corrosion, but it takes longer time for the resulting products to reduce microleakage by sealing the micro-gap at the tooth/amalgam interface., Purpose: The aim of this study was to evaluate the effect of self-etch adhesives with different pH levels on the interfacial corrosion behavior of high-copper amalgam restoration and its induction potential for self-sealing ability of the micro-gap in the early hours after setting by means of Electro-Chemical Tests (ECTs)., Materials and Method: Thirty cylindrical cavities of 4.5mm x 4.7mm were prepared on intact bicuspids. The samples were divided into five main groups of application of Adhesive Resin (AR)/ liner/ None (No), on the cavity floor. The first main group was left without an AR/ liner (No). In the other main groups, the types of AR/ liner used were I-Bond (IB), Clearfil S 3 (S 3 ), Single Bond (SB) and Varnish (V). Each main group (n=6) was divided into two subgroups (n=3) according to the types of the amalgams used, either admixed ANA 2000 (ANA) or spherical Tytin (Tyt). The ECTs, Open Circuit Potential (OCP), and the Linear Polarization Resistance (LPR) for each sample were performed and measured 48 hours after the completion of the samples., Results: The Tyt-No and Tyt-IB samples showed the highest and lowest OCP values respectively. In LPR tests, the Rp values of ANA-V and Tyt-V were the highest (lowest corrosion rate) and contrarily, the ANA-IB and Tyt-IB samples, with the lowest pH levels, represented the lowest Rp values (highest corrosion rates)., Conclusion: Some self-etch adhesives may increase interfacial corrosion potential and self-sealing ability of high-copper amalgams.

Objective: The aim of this study was to evaluate the effect of increased exposure time and light intensity on microhardness of cured composite through different thicknesses of tooth structure in primary teeth., Materials and Methods: One hundred and seventy cylindrical resin composite specimens were prepared. All specimens were divided into 17 experimental and control groups. "Light-emitting diode" light curing unit (LCU) applied directly or through 1, 2, and 3 mm thicknesses tooth slices for experimental groups. The irradiation protocols were 25 and 50 s at 650 mW/cm(2) and 15 and 30 s at 1100 mW/cm(2). The "quartz-tungsten-halogen" LCU (400 mW/cm(2)) for 40 s was used in control group. Microhardness was measured by the Vickers hardness test., Results: Indirectly cured specimens and those cured through a 1 mm thick tooth structure, an increase in intensity caused hardness drop. In the specimens cured through 2 and 3 mm thick tooth structures, increased intensity and/or exposure time did not show any appropriate changes on microhardness., Conclusion: Irradiation through a 1.0 mm thick tooth slice resulted in reduced microhardness although it was still within the clinically acceptable level. The hardness values of the specimens cured through 2 or 3 mm thick tooth slices fell below the clinically acceptable level even after doubling the exposure time and/or light intensity.

Objectives: The objectives were to evaluate the shear bond strength (SBS) of fiber-reinforced composite (FRC) retainers when bonding them to teeth with and without covering the FRC bars using two different adhesive systems., Materials and Methods: Hundred and twenty extracted human maxillary premolars were randomly divided into eight groups (n = 15). FRC bars (4 mm length, Everstick Ortho(®), Stick Tech, Oy, Turku, Finland) were bonded to the proximal (distal) surfaces of the teeth using two different adhesives (Tetric Flow [TF, Ivoclar Vivadent, Switzerland] and resin-modified glass ionomer cement [RMGIC, ODP, Vista, CA, USA]) with and without covering with the same adhesive. Specimens were exposed to thermocycling (625 cycles per day [5-55°C, intervals: 30 s] for 8 days). The SBS test was then performed using the universal testing machine (Zwick, GMBH, Ulm, Germany). After debonding, the remaining adhesive on the teeth was recorded by the adhesive remnant index (0-3)., Results: The lowest mean SBS (standard deviation) was found in the TF group without covering with adhesive (12.6 [2.11] MPa), and the highest bond strength was in the TF group with covering with adhesive (16.01 [1.09] MPa). Overall, the uncovered RMGIC (15.65 [3.57] MPa) provided a higher SBS compared to the uncovered TF. Covering of FRC with TF led to a significant increase in SBS (P = 0.001), but this was not true for RMGIC (P = 0.807). Thermal cycling did not significantly change the SBS values (P = 0.537). Overall, eight groups were statistically different (ANOVA test, F = 3.32, P = 0.034), but no significant differences in bond failure locations were found between the groups (Fisher's exact tests, P = 0.92)., Conclusions: The present findings showed no significant differences between SBS of FRC bars with and without covering by RMGIC. However, when using TF, there was a significant difference in SBS measurements between covering and noncovering groups. Therefore, the use of RMGIC without covering FRC bars can be suggested, which can be validated with in vivo studies.

Background: Although using light-cured composites for bonding orthodontic brackets has become increasingly popular, curing light cannot penetrate the metallic bulk of brackets and polymerization of composites is limited to the edges. Limited access and poor direct sight may be a problem in the posterior teeth. Meanwhile, effectiveness of the trans-illumination technique is questionable due to increased bucco-lingual thickness of the posterior teeth. Light-emitting diode (LED) light-curing units cause less temperature rise and lower risk to the pulpal tissue. The purpose of this study was to evaluate the clinical effectiveness of trans-illumination technique in bonding metallic brackets to premolars, using different light intensities and curing times of an LED light-curing unit., Methods: Sixty premolars were randomly divided into six groups. Bonding of brackets was done with 40- and 80-s light curing from the buccal or lingual aspect with different intensities. Shear bond strengths of brackets were measured using a universal testing machine. Data were analyzed by one-way analysis of variance test and Duncan's post hoc test., Results: The highest shear bond belonged to group 2 (high intensity, 40 s, buccal) and the lowest belonged to group 3 (low intensity, 40 s, lingual). Bond strength means in control groups were significantly higher than those in experimental groups., Conclusions: In all experimental groups except group 6 (80 s, high intensity, lingual), shear bond strength was below the clinically accepted values. In clinical limitations where light curing from the same side of the bracket is not possible, doubling the curing time and increasing the light intensity during trans-illumination are recommended for achieving acceptable bond strengths.

Background and Aims: Adhesive permeability is hindered by application of an additional layer of hydrophobic resin, which increases its concentration within the hydrophilic layer, reduces its affinity to water, and enhances its physical prop-erties. The aim of the present study was to evaluate the effect of a hydrophobic layer on the microleakage of class V composite restorations using different adhesives., Materials and Methods: The adhesives including total-etch Scotchbond MP and Single Bond, and the self-etch Clearfil SE Bond and Clearfil S3 Bond were applied to 80 class V cavities in vitro on the buccal surface in CEJ and then were fol-lowed by hydrophobic resin (Margin Bond) in half of the cavities in each group (n=10). After restoration with microhybrid composite, Z100 and immersion in fuchsine, the degree of microleakage was assessed. Data were analyzed using the Krus-kal-Wallis, Man-Whitney, and Wilcoxon tests., Results: The hydrophobic layer significantly reduced the microleakage of Clearfil SE Bond and Clearfil S3 Bond only in dentin (p<0.05). There was no significant difference between enamel and dentinal margins in Clearfil S3 Bond, Clearfil SE Bond plus Margin Bond, and Clearfil S3 Bond plus Margin Bond (p>0.05)., Conclusion: Within the limitation of this study, only Clearfil S3 Bond could demonstrate the identical values of microle-akage in enamel and dentinal margins.

Aim: The purpose of this laboratory research was to compare the accuracy of digital and conventional bitewing radiographs in the diagnosis of recurrent caries under class II amalgam restorations., Methods and Materials: This study involved 82 posterior intact teeth in which class II amalgam boxes were prepared. Carious lesions were simulated in half of the proximal boxes in the intersection between the facial or lingual wall and the gingival floor or midway between the facial and lingual walls. The other half of each tooth specimen served as a control. The prepared boxes were then restored with a Tytin FC (Kerr, USA) amalgam. The teeth were radiographed in the bucco-lingual direction to obtain images comparable to bitewing. Digital radiographs made with an intraoral CCD sensor and conventional radiography with dental E film were used. Three expert observers evaluated both types of images for the diagnosis of recurrent caries., Results: Sensitivity and specificity values for direct digital radiography were 73 and 95 percent at the buccal and lingual line angles, respectively, and 29 and 90 percent at the mid-gingival floor, respectively. These corresponding values for conventional radiography were respectively 63 and 93 percent at the buccal line angle, 61 and 93 percent at the lingual line angle, and 44 and 95 percent at the mid-gingival floor. The total sensitivity and specificity values were 58 and 93 percent for digital radiography and 56 and 93 percent for conventional radiography. The overall accuracy was 76 percent for digital and 75 percent for conventional radiography. No significant difference in specificity or sensitivity was found between the digital and conventional radiography (p=0.104). Separately, no significant difference was seen between the buccal line angle and the mid-gingival floor, but a significant difference was seen between the two methods in the lingual line angle (p=0.004)., Conclusion: The digital and conventional bitewing radiographs had similar diagnostic accuracy for the diagnosis of recurrent caries. Lesions located at the buccal or lingual line angle were more easily detected than those at the mid-gingival region., Clinical Significance: Although there was no significant difference between digital and conventional radiography in the diagnosis of recurrent caries, digital radiography requires less ionizing radiation, making this method of imaging suggested for routine dental practice.

Aim: Core buildup composite resins with prefabricated posts are commonly used to restore endodontically treated teeth. This study compared the sealing ability of Core Max II and Panavia F2.0 cement with total-etch and self-etch adhesive systems., Methods and Materials: Sixty recently extracted human second premolar teeth were chosen and their crowns were cut 3 mm above the CEJ. After preparing proximal boxes (4+/-1 mm buccolingually and 3 mm occlusogingivally dimensions) and finishing root canal therapy, the teeth were randomly divided into four groups (n=15): groups 1 and 2, Core Max II without and with total-etch adhesive; groups 3 and 4, Clearfil photocore composite, A2 shade, and Panavia F2.0 cement without and with self-etch adhesive respectively. The Dentatus posts (# 2 Long) were used in canals approximately 8 mm depth. According to manufacturer guidelines, pins were cemented and cores were restored. After keeping the specimens for 24 hours at 37 degrees C and 100% humidity, they were thermally cycled for 500 cycles, sealed with nail varnish except 1 mm beyond the margins of restoration, and then immersed in a 0.5% fuschin basic for 24 hours. Samples were embedded in clear epoxy resin, sectioned mesiodistally, and observed at 20x magnification. The microleakage was assessed under stereomicroscope and the results were recorded in percentage of dye penetration to the whole path from the cavosurface margin of the proximal boxes to the end of the post. Analysis of variance and the Tukey test were used to evaluate the data (p=0.05)., Results: Groups 1 and 4 had the highest and the lowest values of microleakage respectively. Microleakage of Panavia F2.0 cement was lower than for Core Max II and for both cements using adhesive made the microleakage smaller than without it (p<0.05)., Conclusion: Application of adhesive using Core Max II cement and Panavia F2.0 cement is strongly recommended to decrease microleakage. Self-etch adhesive performed better than total-etch adhesive., Clinical Significance: With regards to microleakage, the self-etching primer displayed better sealing than that obtained with the total-etching, two-step dental adhesive.

Background: Fibre reinforced composites (FRC) can be used to join teeth as a rigid unit for anchorage purposes and/or for tooth movement. The utility of FRCs for these applications depends on the fracture characteristics and durability of the material under masticatory loads., Aims: To evaluate the effect of simulated masticatory loads on the fracture characteristics of FRC bars joining two bicuspids., Methods: Eighty extracted maxillary bicuspids were used. Pairs of bicuspids were joined with FRC bars on the buccal surfaces. The specimens were divided into two equal groups. In group A the fracture loads of the FRC bars were measured, and in group B the specimens were placed in a simulator and subjected to 4x10(5) chewing cycles, simulating a 2-year period of mastication. At the conclusion of this test the fracture loads of the FRC bars were measured in the intact specimens. All specimens were examined stereomicroscopically to determine the fracture pattern., Results: There were no bond failures in group B during the simulated masticatory forces. The mean fracture loads in groups A and B were 195.8 N and 190.6 N, respectively. Stereomicroscopic examination showed that most fractures occurred at the enamel-composite interfaces in both groups. There were no significant differences between the groups in the fracture loads and fracture patterns., Conclusions: Fibre reinforced composite bars bonded to bicuspids had sufficient durability to withstand the loads simulating a 2-year period of function. The fracture loads and fracture patterns of the FRC bars were not affected by the loads exerted by the simulator.