Journal of Dentistry of Tehran University of Medical Sciences最新文献

Objectives: The main disadvantage of fiber posts is their low bond strength to root canal wall. The aim of the present study was to assess the effect of different root canal post space treatments on push-out bond strength of fiber posts to root canal dentin.

Materials and methods: After post space preparation in 40 endodontically treated human premolars, the teeth were randomly divided into four experimental groups: Group 1: control group, group 2: Endsolv R, group 3: ultrasonic cleaning, group 4: Clearfil Repair. Afterwards, the posts were bonded with Panavia F 2.0 bonding cement. The bond strength of fiber posts to root canal wall in the middle part of canal was evaluated following thermocycling using push-out test. Data were analyzed using one-way ANOVA and Tamhane's multiple comparisons test. The failure mode of each group was determined under a stereomicroscope.

Results: There was a significant difference in the mean push-out bond strength among the groups (P<0.05). The lowest bond strength was noted in the control group. The control group had significant differences with ultrasonic and Clearfil Repair groups (P<0.05). The bond strength of Endsolv R group increased; however, it was not significant (P>0.05).

Conclusions: It seems that ultrasonic cleaning and Clearfil Repair can modify the root canal wall and significantly increase the bond strength of fiber posts.

Objectives: The aim of this study was to evaluate and compare the retentive strength of orthodontic bands cemented with amorphous calcium phosphate (ACP)-containing and conventional glass ionomer cements (GICs).

Materials and methods: One-hundred-and-twenty mandibular third molars were embedded in acrylic resin blocks with the buccal surface of crowns perpendicular to the base of the mold. The teeth were randomly divided into four groups containing 30 teeth each. Groups 1 and 3 were cemented using conventional GIC and groups 2 and 4 were cemented using ACP-containing orthodontic cement. Groups 1 and 2 without thermocycling, and groups 3 and 4 after thermocycling (5000 cycles, 5° to 55°C) were tested for retentive strength using a universal testing machine (crosshead speed of 1mm/minute). Two-way ANOVA was performed to compare the retentive strength of the groups.

Results: The highest retentive strength belonged to group 1, and it was significantly higher than that of group 2 (P<0.001) and group 3 (P=0.02). The mean strength for group 2 was significantly lower than that of group 1 (P<0.001) and group 4 (P=0.04).

Conclusions: Although retentive strength decreased when ACP was added to GIC, the retentive strength of the samples cemented by ACP-containing GIC was remarkably high after thermocycling. It seems that in the oral cavity, ACP-containing GIC provides sufficient strength to endure forces applied on posterior teeth.

Objectives: Indicators of oral health-related quality of life (OHRQoL) in children are widely adopted to evaluate the effects of oral problems. Recently, the scale of oral health outcomes for 5-year-old children (SOHO-5) was developed based on the children's self-reports. This study aimed to evaluate the validity and reliability of the Persian version of the questionnaire in a sample of Iranian children.

Materials and methods: This cross-sectional study was conducted on 160 children from four areas of Isfahan selected via non-random purposive sampling. After forward-backward translation of the questionnaire, content and face validity evaluation, a pilot test was carried out. Children forms were completed by interview, while parents forms were self-administered. Test-retest reliability was evaluated in 30 subjects. Construct validity, internal consistency and descriptive quality of life score were assessed with SPSS 18. The child-parent agreement was measured with correlation test and paired t-test (α=0.05).

Results: The mean (±standard deviation) quality of life scores in children and parents were 2.3±3 and 1.3±1.9, respectively. The most prevalent impacts were difficulty sleeping and eating. The Cronbach's alpha coefficients were 0.82 and 0.67 for the child and parent versions, respectively. Significant correlation of the scores with the oral health rating, pain history and perceived need for treatment confirmed its construct validity (r: 0.4-0.6, P<0.05). The hypothesis of the agreement was not supported (P>0.05).

Conclusions: Based on the findings, the Persian version of SOHO-5 has acceptable reliability and validity for use in the pediatric population of Iran while there were some conflicts by parents.

Objectives: This study aimed to evaluate the effect of storage period on dimensional stability of Alginplus and Hydrogum 5.

Materials and methods: In this in vitro experimental study, 60 impressions were taken of an upper jaw typodont, including 10 impressions for each storage period to be tested (12 minutes, 24 and 120 hours) for each type of alginate. Then, the impressions were stored in an incubator with stable temperature and humidity, and poured using a type III dental stone. Subsequently, the mesiodistal dimension, occlusogingival height, and interarch distance were measured using a digital caliper with an accuracy of 0.01mm. The data were analyzed using ANOVA and t-test (P<0.05).

Results: Alginplus and Hydrogum 5 impressions were not significantly different from the master model after 12 minutes and 24 hours in terms of dimensions (P>0.05). After 120 hours, all dimensions measured on casts were significantly different from those measured on the master model, except for the mesiodistal dimension of the Hydrogum 5 impressions.

Conclusions: At a consistent temperature and humidity, the Alginplus and Hydrogum 5 impressions were dimensionally stable for at least 24 hours.

Objectives: The aim of this study was to compare the accuracy of dental implant impressions obtained by a combination of different impression techniques and viscosities of polyvinyl siloxane (PVS).

Materials and methods: Four parallel fixtures were placed between mental foramina in a master model of lower dental arch. Three different viscosities (putty/light body, medium body/light body, and monophase: heavy body) and direct and indirect techniques (six groups) were used, and seven impressions were obtained from each group (n=42). To measure the accuracy of impressions, drift, horizontal, and vertical angles of the implants, as well as the hex rotation of the implants in casts were evaluated using a digitizer device (1μm accuracy), in comparison with master arch. Data were analyzed using five-factor two-way ANOVA and Tukey's post-hoc test.

Results: The accuracy of impressions was assessed and the results showed that direct technique was not significantly different from indirect technique (P>0.05). Also, there were no significant differences between the mentioned viscosities except for the horizontal angle (P=0.006).

Conclusions: Viscosity of impression materials is of high significance for the accuracy of dental impressions.

Objectives: The aim of the present study was to compare the effects of intranasal ketamine and midazolam on behavior of 3-6 year-old children during dental treatments.

Materials and methods: In this randomized cross-over clinical trial, 17 uncooperative children requiring at least two dental treatments were selected and randomly received ketamine (0.5mg/kg) or midazolam (0.2mg/kg) prior to treatment. The other medication was used in the next visit. The children's behavioral pattern was determined according to the Houpt's scale regarding sleep, movement, crying and overall behavior. Physiological parameters were also measured at different time intervals. The data were subjected to Wilcoxon Signed Rank test and two-way repeated measures ANOVA.

Results: The frequency of crying decreased significantly following ketamine administration compared to midazolam (P=0.002); movement of children decreased with fewer incidence of treatment interruption (P=0.001) while their sleepiness increased (P=0.003). Despite higher success of sedation with ketamine compared to midazolam, no significant differences were found between the two regarding patients' overall behavior (P>0.05). The patients had higher heart rate and blood pressure with ketamine; however, no significant difference was found regarding respiratory rate and oxygen saturation (P>0.05).

Conclusions: Ketamine (0.5mg/kg) led to fewer movements, less crying and more sleepiness compared to midazolam (0.2mg/kg). No significant differences were found between the two drugs regarding children's overall behavior and sedation efficiency. Both drugs demonstrated positive efficacy for sedation of children during dental treatments.

Objectives: The aim of this study was to evaluate the effect of conventional and high-power light emitting diode (LED) light curing units on shear bond strength (SBS) of metal and ceramic brackets to tooth surface.

Materials and methods: Forty sound bovine maxillary central incisors were used for the study. The teeth were divided into four groups (n=10). Teeth surfaces were etched with 37% phosphoric acid for 20 seconds. After applying a uniform layer of adhesive primer on the etched enamel, composite was placed on the base of brackets. The samples were light cured according to the manufacturer's instructions and thermocycled. The SBS was measured. The failure mode was scored using the adhesive remnant index (ARI).

Results: The mean SBS of samples in groups A (high-power LED, metal bracket), B (high-power LED, ceramic bracket), C (conventional LED, metal bracket) and D (conventional LED, ceramic bracket) was 23.1±3.69, 10.7±2.06, 24.92±6.37 and 10.74±3.18MPa, respectively. The interaction effect of type of LED unit (high-power/conventional) and bracket type on SBS was not statistically significant (P=0.483). In general, type of LED unit did not affect SBS. Type of bracket significantly affected SBS (P<0.001). The ARI score was not significantly influenced by the interaction between the type of LED unit and bracket.

Conclusions: The obtained SBS is the same for both bracket types by use of high-power and conventional LED light curing units. Regardless of the type of LED unit, SBS of ceramic brackets was significantly lower than that of metal brackets.

Objectives: Dental composite wear in posterior restorations is a concern and is affected by different factors. This study was conducted to evaluate the effect of polishing and mechanical loads on wear of silorane-based and methyl methacrylate-based composites resins.

Materials and methods: Of each dental composite (Filtek P90 and Filtek P60), 40 samples were fabricated in a polyethylene mold (4mm diameter, 10mm height). According to the finishing and/or polishing protocols (180-grit or 2500-grit silicon carbide papers), the samples of each composite were divided into two groups. Surface roughness (R _ә ) was measured and recorded using a contact profilometer. The weight of each sample was also measured in grams. The wear test was performed in a pin-on-disc device under two different loads (70N, 150N). Afterwards, samples were subjected to profilometry and their weight was measured again. Data were analyzed using t-test and univariate ANOVA. P <0.05 was considered statistically significant.

Results: Higher mechanical load resulted in greater weight loss (P<0.001). Samples polished with 2500-grit papers showed significantly lower Ra changes compared to those polished with 180-grit papers (P<0.001). Filtek P90 had greater weight loss than Filtek P60 except in one condition (180-grit, 70N).

Conclusions: Results showed that wear of posterior composite restorations depends on mechanical load, type of composite resin and surface properties.

Objectives: During root canal preparation, apical extrusion of debris can cause inflammation, flare-ups, and delayed healing. Therefore, instrumentation techniques that cause the least extrusion of debris are desirable. This study aimed to compare apical extrusion of debris by five single-file, full-sequence rotary and reciprocating systems.

Materials and methods: One hundred twenty human mandibular premolars with similar root lengths, apical diameters, and canal curvatures were selected and randomly assigned to six groups (n=20): Reciproc R25 (25, 0.08), WaveOne Primary (25, 0.08), OneShape (25, 0.06), F360 (25, 0.04), Neoniti A1 (25, 0.08), and ProTaper Universal. Instrumentation of the root canals was performed in accordance with the manufacturers' instructions. Each tooth's debris was collected in a pre-weighed vial. After drying the debris in an incubator, the mass was measured three times consecutively; the mean was then calculated. The preparation time by each system was also measured. For data analysis, one-way ANOVA and Games-Howell post hoc test were used.

Results: The mean masses (±standard deviation) of the apical debris were as follows: 2.071±1.38mg (ProTaper Universal), 1.702±1.306mg (Neoniti A1), 1.295±0.839mg (OneShape), 1.109±0.676mg (WaveOne), 0.976±0.478mg (Reciproc) and 0.797±0.531mg (F360). Compared to ProTaper Universal, F360 generated significantly less debris (P=0.02). The ProTaper system required the longest preparation time (mean=88.6 seconds); the Reciproc (P=0.008), OneShape (P=0.006), and F360 (P=0.001) required significantly less time (P<0.05).

Conclusions: All instruments caused extrusion of debris through the apex. The F360 produced significantly less debris than did the ProTaper Universal.

Trauma to primary teeth can lead to devastating sequels in development of permanent successors. The disturbance may range from enamel hypoplasia and/or hypo-calcification to arrest of dental bud development. Crown dilaceration of permanent teeth is one of the consequences of trauma to deciduous teeth mainly due to intrusion or avulsion. This report presents a mandibular central incisor with dilacerated crown and yellowish discoloration with symptomatic apical abscess. History revealed avulsion of primary mandibular central incisors. The purpose of this report is to present: 1. Reasons of dilacerated crown, yellowish discoloration and necrotic pulp in this case, 2. Treatment options in different types of crown dilacerations and also in this case. The tooth was successfully managed by nonsurgical root canal therapy and restoration with composite resin to restore esthetics. We emphasize that trauma to deciduous teeth should not be understated, and regular follow up is essential.