Assessment of Bond Strength between Metal Brackets and Non-Glazed Ceramic in Different Surface Treatment Methods

Objective: The aim of this study was to evaluate the bond strength between metal brackets and non-glazed ceramic with three different surface treatment methods.Materials and Methods: Forty-two non-glazed ceramic disks were assigned into three groups. Group I and II specimens were etched with 9.5% hydrofluoric acid. Subsequently in group I, silane and adhesive were applied and in group II, bonding agent was used only.In group III, specimens were treated with 35% phosphoric acid and then silane and adhesive were applied. Brackets were bonded with light-cured composites. The specimens were stored in water in room temperature for 24 hours and then thermocycled 500 times between 5°C and 55°C.Results: The difference of tensile bond strength between groups I and III was not significant(P=0.999). However, the tensile bond strength of group II was significantly lower than groups I, and III (P<0.001). The adhesive remnant index scores between the threegroups had statistically significant differences (P<0.001).Conclusion: With the application of scotch bond multi-purpose plus adhesive, we can use phosphoric acid instead of hydrofluoric acid for bonding brackets to non-glazed ceramic restorations

Radiographic Vertical Bone Loss Evaluation around Dental Implants Following One Year of Functional Loading

Objective: Vertical bone loss evaluations in the Nobel Biocare Replace® Select Tapered TM implant system in the human after one-year loading time.Materials and Methods: This retrospective cross-sectional study was performed on 31 patients (14 men, 17 women; mean age, 60.39 years) receiving 170 implants (mean, 5.48 for each patient) of Groovy and Non-groovy designs in the Nobel Biocare Replace® Select Tapered TM system. The marginal bone loss was measured at mesial and distal aspects of the implants on OPG x-rays after one-year follow-up. The data regarding the patient's gender, age, history of disease, smoking, bone type at implant location, loading time of prosthesis and implant, implant design, diameter and length were recorded by the patients'records and interview. The data were subjected to multiple linear regression and Pearson coefficient ratio regarding different factors.Results: The mean (standard deviation) distal, mesial and overall bone loss was 0.688 mm (0.851), 0.665 mm (0.849) and 0.935 mm (0.905), respectively in the studied implants. No significant differences were found regarding implant location, bone quality at the implant region, implant design and bone graft reception. In addition, no significant correlation was found between the occurred bone loss and implant diameter, length and number of usedsplints.Conclusion: Due to the criteria mentioned for implant success in term of bone loss values after one-year loading time, Noble Biocare Replace® Select Tapered TM implant system is an acceptable treatment option for implant restorations in this regard

Shear Bond Strength of Composite to Nd-YAG Lased Dentin with and without Dye

Statement of Problem: The achievement of a good and durable dentin/composite resin bond is an important task in restorative dentistry. The application of acid conditioners and dentin bonding agents is an accepted method to enhance this bond strength. Pretreating of dentin surface by laser irradiation seems to be a supplemental way to obtain better results,since lased dentin is more roughened and has a widest surface area to interact with acidconditioner.Purpose: In this study, the effect of dentin surface pretreating by Nd-YAG laser on dentin/composite shear bond strength was examined. Moreover, the effect of Chinese ink as a surface energy absorber on this value was investigated.Methods and Materials: Thirty-nine freshly extracted human teeth without dentinal caries were collected and their occlusal dentins were exposed using a diamond disk. The collected samples were divided into three identical groups. The dentin surface of the first group was lased by an Nd-YAG pulsed laser (100 mJ, 20 Hz) through a 320 mm fiber optic in a swiping movement. In the second group, 10% solution of Chinese ink was applied on the dentinal surface before lasing. The samples of the third group were not lased at all. Thedentinal surface prepared by 35% phosphoric acid and Scotchbond MP primer and adhesive. Then, composite resin was cured on dentinal surface. After incubation, in water at 37°C for 24 hours, the samples were tested by Digital Tritest ELE machine.Results: The values of bond strength were 20.83±3.96 MPa, 17.83±3.63 MPa and 19.38±4.88 MPa for the lased, unlased and dye-enhanced groups, respectively. The results were not significant by ANOVA test (a=0.05). Although in the Weiboul modulus, the lased group offered better bond strength.Conclusion: Further studies are required to determine whether chemical as well as physical alterations to the dentin surface are induced by laser etching, and whether these influence the performance of the range of dentin bonding systems used currently in clinical practice

Evaluation of two electronic apex locator of 4th generation, Raypex4 and Apit7, in canal length determination

Background and Aim: Determining correct working length in root canal therapy is of great importance in successful treatment. The purpose of this study was to compare the accuracy of two electronic apex locators of fourth generation, Raypex4 and Apit7, in determining working length in vivo. Materials and Methods: In this test evaluation study performed at Dental School of Tehran University, a total of 32 single canal vital teeth planned for extraction because of orthodontic and prosthetic reasons were selected. Working length determination by each of the two electronic apex locators was performed by two different dentists. These measurements were compared with direct visual measurement after tooth extraction. The dentists working with devices and the endodontist who determined the working length of the extracted teeth as well as the statistician, all were blind regarding the results. The data were compared using binominal distribution test with P&lt;0.05 as the limit of significance. Results: The accuracy of actual length determination of Raypex4 was 68.8% in the limit of ± 0.5 and 83.3% in the limit of ±1. From the actual length measurements, 75.1% were within the tolerance of +0.5 to-1. The accuracy of the working length determination by Raypex4 was 68.8% within the tolerance of ± 0.5 and 84.3% within the tolerance of ± 1. Taking the tolerance of + 0.5 to -1 mm into account, the accuracy of the instrument was about 78.8%. The accuracy of actual length determination of Apit7 was 65.7% in the limit of ±0.5 and 78.3% in the limit of ±1. Compared to the visual length determination, 78.8% of the actual length measurements were within the tolerance of +0.5 to-1. The accuracy of the working length determination was 62.6% within the tolerance of ±0.5 and 81.3% within the tolerance of ±1. Taking the tolerance of + 0.5 to -1 mm into account, the accuracy of the instrument was about 75.1%. Conclusion: Raypex4 and Apit7 had similar accuracy in determining the actual length. However, they still can not replace the routine methods of actual length determination

Effect of three porcelain etchants type (HF-APF-PHA) on porcelain- composite shear bond strength

Statement of Problem: Porcelain restorations are susceptible to fracture and a common method for repairing is the use of silane and composite on etched porcelain. Although HF is very effective in porcelain etching but has detrimental effects on tissues. Purpose: In this study, the effect of APF and PHA was compared with HF in porcelain etching. Also the role of silane, unfilled resin and dentin bonding in bond strength of composite- porcelain was evaluated. Methods and Materials: In this experimental in-vitro study, one-hundred twenty porcelain square blocks (5&amp;#61620;5&amp;#61620;2 mm) were prepared and bonding surfaces of each sandblasted. Samples were divided into three groups. The first group (n=40) were etched with buffered HF 9.5% (Ultradent) for 1 min., the second group (n=40) were etched with Iranian APF 1.23% (Kimia) for 10 minutes and the third group (n=40) were etched with Iranian PHA 37% (Kimia) for 1 min. Ultradent silane was applied on the surfaces of half of cases in each group. On the surfaces of half of silane-treated samples unfilled resin was applied and dentin bonding was used on the surfaces of the remaining. Samples without silane were treated in a similar manner. Composite cylinder with 4mm diameter and 2 mm height was bonded to porcelain. Specimens were stored in 37°C distilled water for 24 hours and subjected to 500 cycles. Shear bond strength was measured with an Instron machine and type of fracture was evaluated using a stereomicroscope. Results were analyzed using 3 way ANOVA, Kaplan- Maier and Tukey HSD tests. Results: Findings showed that PHA and APF roughened the porcelain surface without creating retentive micro undercuts but HF etches porcelain and creates retentive microundercuts. Ultradent silane had no significant effect on bond strength of porcelain- composite. Unfilled resin with Ultradent silane compared with dentin bonding with the same silane is more effective in bond strength of composite- porcelain. Conclusion: Based on present study, application of Ultradent silane on sandblasted and etched porcelain with PHA or APF cannot be used as an alternative to this silane on sandblasted and etched porcelain with HF

An evaluation on the accuracy of an electronic apex Locator (EAL) in the determination of working length inprimary teeth (In-vitro)

Statement of Problem: Radiography is the most common technique in working length determination, however, because of its limitations is not considered as an ideal technique. Its application, particularly for children due to radiation hazards, technical problems in young and unco-operative children and the superimposition of permanent teeth bud on primary teeth root, lead to numerous problems.&quot;nPurpose: The goal of this study was to evaluate the accuracy of an electronic apex locator (EAL) in working length determination of primary teeth.&quot;nMaterials and Methods: In this in-vitro study 96 canals of the extracted primary teeth, with at least 2/3 of the root length remained, were investigated. There were no obstructed canal, previous root canal therapy and perforation of pulp chamber floor. All working lengths were also measured by radiography. The results of Raypex 4 and radiography were compared with actual root canal lengths determined by direct observation. The applied EAL, in this study was called Raypex 4, a new device belonged to the fourth generation (Ratio Type). The results were analyzed by Chi-Square and Pearson correlation statistical tests.&quot;nResults: The accuracy of Raypex and radiography were 61.5% and 63.5%, respectively. The differences between Reypex 4 root canal length measurements and those of direct observation were not significant (P=0.08), but such difference between radiography and direct observation was statistically significant (P=0.01). The diameter of the apical foramen (the site of canal opening) did not affect on Raypex 4 accuray (P&amp;gt;0.05).&quot;nConclusion: Considering the acceptable safetyness, Painlessness, simple and rapid application and an accuracy comparable to that of radiography, the use of Raypex4 EAL for the measurement of primary teeth length is suggested

Comparison of Formocresol and Ferric Sulfate Pulpotomy in Primary Molars: A Systematic Review and Meta-analysis

Objective: Several studies have compared ferric sulfate and formocresol pulpotomy in primary molars. The results of these studies, however, could not be compared due to differencesin evaluated outcomes (clinical, radiographic, or histologic) and follow up duration.The aim of the present study was a systematic review of similar studies and a metaanalysis of their results to provide the latest evidence on the issue.Materials and Methods: Web-based search was done in EMBASE,Cochrane, Pubmed,Google Scholar, IranMedex, Scientific Citation Index (SCI), and Scopus index databases.A hand search also was conducted in scientific and research dental journals approved by the Ministry of Health and Medical Education of Iran. Eight randomized clinical trial articles were selected. Clinical success, clinical and radiographic success (total success) rate were assessed as outcome variables. Peto test served for data analysis.Results: The clinical success of formocresol pulpotomy was comparable to that of ferric sulfate (P=0.574). In addition, the difference between total success rate of the two methods in different studies was insignificant (P=0.42).Conclusion: No significant difference existed between the total success rate of formocresol and ferric sulfate pulpotomy, and ferric sulfate can be an appropriate alternative for formocresol