Vol 12, No 3 (2015)
Original Article
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Objectives: Bond strength of composite resin to enamel and dentin of primary teeth is lower than that to permanent teeth; therefore, it may compromise the ad- hesive bonding. New methods, such as laser application have been recently intro- duced for tooth preparation. The purpose of this study was to evaluate the effect of tooth preparation with bur and Er:YAG laser on shear bond strength of com- posite to enamel and dentin of primary teeth.
Materials and Methods: Seventy-five primary molar teeth were collected and 150 specimens were obtained by mesiodistal sectioning of each tooth. In each of the enamel and dentin groups, the teeth were randomly assigned to 3 subgroups with the following preparations: bur preparation + etching (37% H3PO4), laser preparation + etching, and laser preparation without etching. Single Bond adhe- sive and Z250 composite were applied to all samples. After thermocycling, the shear bond strength testing was preformed using the Instron Testing Machine. Data were analysed using SPSS-17 and two-way ANOVA.
Results: The bond strength of enamel specimens was significantly higher than that of dentin specimens, except for the laser-non-etched groups. The enamel and dentin laser-non-etched groups had no significant difference in bond strength. In both enamel and dentin groups, bur preparation + etching yielded the highest bond strength, followed by laser preparation + etching, and the laser preparation with- out etching yielded the lowest bond strength (P < 0.001).
Conclusion: In both enamel and dentin groups, laser preparation caused lower shear bond strength compared to bur preparation.
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Objectives: Cases of antimicrobial resistance are increasing, partly due to inappropriate prescribing practices by dentists. The purpose of this study was to investigate the prescrib- ing practices and knowledge of dentists with regards to antibiotics. Moreover, this study aimed to determine whether the prescriptions comply with the recommended guidelines and whether clinical audit can alter the prescribing practices of dentists leading to better use of antibiotics in the dental service.
Materials and Methods: A clinical audit (before/after non-controlled trial) was carried out in two dental clinics in the northeast of England. Retrospective data were collected from 30 antibiotic prescriptions, analysed and compared with the recommended guide- lines. Data collected included age and gender of patients, type of prescribed antibiotics and their dosage, frequency and duration, clinical condition and reason for prescribing. The principles of appropriate prescribing based on guidance by the Faculty of General Dental Practice in the United Kingdom (UK), FGDP, were discussed with the dental clini- cians. Following this, prospective data were collected and similarly managed. Pre and post audit data were then compared. Changes were tested for significance using McNemar's test and P value<0.05 was considered statistically significant.
Results: After intervention, data revealed that antibiotic prescribing practices of dentists improved, as there was an increase in the percentage of prescriptions that were in accor- dance with the FGDP (UK) guidelines.
Conclusion: In view of the limited data collected, this study concludes that there are inap- propriate antibiotic prescribing practices amongst general dental practitioners and that clinical audit can address this situation, leading to a more rational use of antibiotics in dental practice.
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Objectives: Caries and dental trauma are common reasons for primary anterior teeth restorations in children. This non-control clinical trial was designed to eva- luate crown restorations reinforced with a sectioned file post for the restoration of severely damaged primary maxillary incisors.
Materials and Methods: Thirty-eight primary maxillary incisors of 12 children (3-5 years old) with early childhood caries (ECC) received composite restorations with a custom made post. The restorations were evaluated using the modified United State Public Health Service (USPHS) criteria. The results were statistically analyzed by descriptive –analytical tests.
Results: In this trial, the quality of marginal adaptation decreased after three and 12 months intervals. Recurrent carious lesions were observed during intervals. In terms of restoration retention, only one patient lost both the post and the restora- tion at the 12-month follow up.
Conclusion: The sectioned file post technique showed good retention and aesthet- ics for restoring severely damaged primary maxillary anterior teeth.
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Objectives: The aim of the present randomized clinical trial was to evaluate marginal bone loss around two types of implants modified at the neck area: Nobel Active and Nobel Replace Groovy, both manufactured by Nobel Biocare.
Materials and Methods: A total of 25 Nobel Active and 21 Nobel Replace Groovy implants were included in the present study. The implants were placed based on the relevant protocol and patient inclusion and exclusion criteria. The amount of bone loss around implants was compared at 6 and 12-month intervals using digital periapical radiographs.
Results: The mean bone loss values in the Nobel Active and Nobel Replace Groovy groups were 0.682 mm and 0.645 mm, respectively, with no statistically significant difference based on the results of independent t-test (P=0.802).
Conclusion: Use of both implant types yielded favorable results, with high durability.The two implant types exhibited no superiority over each other in terms of bone loss.
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Objectives: The objective of this study was to assess the effect of new bonding techniques on enamel surface.
Materials and Methods: Sixty upper central incisors were randomly divided into two equal groups. In the first group, metal brackets were bonded using Trans- bondXT and, in the second group, the same brackets were bonded with MaxcemElite. The shear bond strength (SBS) of both agents to enamel was measured and the number and length of enamel cracks before bonding, after debonding and after polishing were compared. The number of visible cracks and the adhesive remnant index (ARI) scores in each group were also measured.
Results: There were significantly more enamel cracks in the Transbond XT group after debonding and polishing compared to the Maxcem Elite group. There was no significant difference in the length of enamel cracks between the two groups; but, in each group, a significant increase in the length of enamel cracks was noticeable after debonding. Polishing did not cause any statistically significant change in crack length. The SBS of Maxcem Elite was significantly lower than that of Transbond XT (95% confidence interval).
Conclusion: Maxcem Elite offers clinically acceptable bond strength and can thus be used as a routine adhesive for orthodontic purposes since it is less likely todamage the enamel.
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Objectives: Various methods have been introduced for evaluation of tooth movement in orthodontics. The challenge is to adopt the most accurate and most beneficial method for patients. This study was designed to introduce analysis of digital photographs with Auto- CAD software as a method to evaluate tooth movement and assess the reliability of this method.
Materials and Methods: Eighteen patients were evaluated in this study. Three intraoral digital images from the buccal view were captured from each patient in half an hour inter- val. All the photos were sent to AutoCAD software 2011, calibrated and the distance be- tween canine and molar hooks were measured. The data was analyzed using intraclass cor- relation coefficient.
Results: Photographs were found to have high reliability coefficient (P > 0.05). Conclusion: The introduced method is an accurate, efficient and reliable method for eval- uation of tooth movement.
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Objectives: Gastric infection with Helicobacter pylori may be one of the main causes of halitosis. This study was performed to evaluate the relationship of Heli- cobacter pylori infection with halitosis.
Materials and Methods: This case control study was performed on 44 dyspeptic patients with a mean age of 34.29±13.71 years (range 17 to 76 years). The case group included 22 patients with halitosis and no signs of diabetes mellitus, renal or liver failure, upper respiratory tract infection, malignancies, deep carious teeth, severe periodontitis, coated tongue, dry mouth or poor oral hygiene. Control group included 22 patients without halitosis and the same age, sex, systemic and oral conditions as the case group. Halitosis was evaluated using organoleptic test (OLT) and Helicobacter pylori infection was evaluated by Rapid Urease Test (RUT) during endoscopy. The data were statistically analyzed using chi square, Mann Whitney and t-tests.
Results: Helicobacter pylori infection was detected in 20 (91%) out of 22 halitosis patients, and 7 control subjects (32%) (P<0.001).
Conclusion: Helicobacter pylori gastric infection can be a cause of bad breath. Dentists should pay more attention to this infection and refer these patients to in- ternists to prevent further gastrointestinal (GI) complications and probable malig- nancies.
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Objectives: The purpose of this experimental study was to compare the disinfection efficacy of sodium hypochlorite and peroxygenic acid (Virkon) solutions for dental stone casts contaminated with microbial strains.
Materials and Methods: A total of 960 spherical stone beads with a diameter of 10 mm were prepared and used as carriers of bacterial inoculums. They were individually inoculated by soaking in broth culture media containing each of the four understudy microorganisms. Different concentrations of Virkon and hypochlorite solutions were prepared using distilled water and then were sprayed on the surfaces of dental casts contaminated with Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus subtilis and Candida albicans. The pour plate technique was used to evaluate the antimicrobi- al efficacy of each solution. Microbicidal effect (ME) was calculated according to the log10 of control colony counts minus the log10 of the remaining colony counts after the antimicrobial procedure. Statistical difference was assessed using the Kruskal Wallis and the Man Whitney U tests with a significance of 95%.
Results: We observed different bactericidal effects of Virkon at various concentra- tions; 1% Virkon killed S. aureus, P aeruginosa, and Candida albicans, while 3% Virkon solution was required to kill B. subtilis. For S. aureus, P. aeruginosa, and C. albicans, no significant difference was observed between1% Virkon and 0.525% so- dium hypochlorite (P >0.05). For B. subtilis, the efficacy of 3% Virkon and 0.525%sodium hypochlorite was not significantly different (P >0.999).
Conclusion: According to the obtained results for Virkon and based on its low toxici- ty and good environmental compatibility, it may be recommended as an antimicrobial disinfectant for dental stone casts as non-critical items.
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Objectives: This study sought to assess distal and lateral forces and moments of asymmetric headgears by variable outer bow lengths.
Materials and Methods: Four 3D finite element method (FEM) models of a cer- vical headgear attached to the maxillary first molars were designed in SolidWorks2010 software and transferred to ANSYS Workbench ver. 11 software. Modelscontained the first molars, their periodontal ligament (PDL), cancellous and cor- tical bones, a mesiodistal slice of the maxillae and the headgear. Models were the same except for the outer bow length in headgears. The headgear was symmetric in model 1. In models 2 to 4, the headgears were asymmetric in length with dif- ferences of 5mm, 10mm and 15mm, respectively. A 2.5 N force in horizontal plane was applied and the loading manner of each side of the outer bow was cal- culated trigonometrically using data from a volunteer.
Results: The 15mm difference in outer bow length caused the greatest difference in lateral (=0.21 N) and distal (= 1.008 N) forces and also generated moments (5.044 N.mm).
Conclusion: As the difference in outer bow length became greater, asymmetric effects increased. Greater distal force in the longer arm side was associated with greater lateral force towards the shorter arm side and more net yawing moment. Clinical Relevance:A difference range of 1mm to 15 mm of length in cervical headgear can be consi-dered as a safe length of outer bow shortening in clinical use.
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Objectives: The aim of this study was to evaluate marginal adaptation of mineral trioxide aggregate (MTA), calcium enriched mixture (CEM) cement, Biodentine and BioAggregate in presence of normal saline and human blood.
Materials and Methods: In this in-vitro experimental study, 80 extracted single-rooted human teeth were instrumented and filled with gutta-percha. After resect- ing the root-end, apical cavity preparation was done and the teeth were randomly divided into 4 groups (N=20)(a total of 8 subgroups). Root-end filling materials were placed in 3mm root-end cavities prepared ultrasonically. Half the specimens in each group were exposed to normal saline and the other half to fresh whole human blood. After 4 days, epoxy resin replicas of the apical portion of samples were fabricated and scanning electron microscopy (SEM) analysis was performed to find gaps in the adaptation of the root-end filling materials at their interface with dentin. The Kruskal-Wallis and Mann-Whitney tests were used for statistical analysis of data with P<0.05 as the limit of significance.
Results: There were no significant differences in marginal adaptation of the 8 tested groups (P>0.05).
Conclusion: Based on the results, blood contamination does not affect the mar- ginal adaptation of MTA, CEM cement, Biodentine or BioAggregate .
