جستجوی مقالات مرتبط با کلیدواژه « Dental Restoration » در نشریات گروه « پزشکی »

Assessment of dental materials do by different methods. The aim of this study was to compare the flexural strength and surface roughness of temporary crowns manufactured through conventional and digital methods.

An experimental laboratory study was conducted on 60 rod-shaped samples made from three different materials. These materials were ENA high filler flowable composite, CENTRIX self-curing acrylic base composite and 3D printer resin. To create the 3D printer group samples, the original metal model was scanned and the design file was printed using a 3D printer. For the composite samples and acrylic bases, a silicone index was used, which was composed of the original metal model. Ten samples of each material were stored in artificial saliva for 30 days. The samples were then tested for flexural strength and surface roughness. The data collected was analyzed using a one-way analysis of variance, Bonferroni’s post hoc (α =0.05).

The average flexural strength varied significantly among the three materials after being im-mersed in artificial saliva for a month (p<0.001). The ENA flow material's average flexural strength was significantly higher than the CENTRIX material and printed resin (p<0.001), and the CENTRIX material's average flexural strength was significantly higher than printed resin (p<0.001). The CENTRIX material also had a significantly higher initial roughness mean (Ra) value compared to the ENA flow material (p=0.010) and printed resin (p=0.009), while there was no significant difference between the ENA flow mate-rial and printed resin (p=1.00). One month after immersion in artificial saliva, the CENTRIX material's mean surface roughness (Ra) was significantly higher than the ENA flow material (p=0.005) and printed resin (p=0.040).

Flowable composite resin presents better mechanical properties when compared to acrylic base resin and printed resin. The surface roughness of flowable composite and printed resin is lower than acrylic base composite, but the surface roughness of all materials increases when exposed to saliva.
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Although oxidative mouthwashes have many antimicrobial benefits, it has been suggested that residual oxygen interferes with composite resin adhesion to dental structures. This study aimed to evaluate the effect of an oxidative mouthwash on the microleakage of composite restorations. Twenty-four extracted human third molars were randomly assigned into three groups: Group 1: a 0.05% sodium fluoride mouthwash, Group 2: an oxidative mouthwash, and Group 3: distilled water. The teeth were immersed in the corresponding solution for 10 minutes a day over 14 days. Class V cavities were prepared in the buccal and lingual surfaces of the teeth (n=15 per group) and restored with Filtek Z250 composite. The teeth were thermocycled between 5º C and 55º C for 1000 cycles, then immersed in 2% fuchsin solution for 24 hours, followed by sectioning in the bucco-lingual direction. The gingival and occlusal microleakage were inspected using a stereomicroscope. Data were analyzed using Kruskal-Wallis and Mann-Whitney U tests. The statistical significance level was considered at P 0.05. The highest and lowest average microleakage scores were observed at the gingival and occlusal margin of cavities immersed in the sodium fluoride mouthwash, respectively. No statistical differences were observed in microleakage among the three groups either at the occlusal or at the gingival margin (P>0.05). The Mann-Whitney U test showed a statistically greater microleakage at the cervical (1.05±1.1) compared to the occlusal (0.694±0.53) margins, irrespective of the treatment groups (P=0.033). Using an oxidative mouthwash does not affect the microleakage of composite restorations

Statement of the Problem: 

By development of adhesive dentistry and noble mechanical strength of ceramics, reconstruction of posterior teeth with partial coverage restorations such as ceramic endocrowns is possible. Different ceramics may show different mechanical properties which should be investigated.

The aim of this experimental in vitro study was to compare the tensile bond strength of endocrowns made by CAD-CAM using 3 types of ceramics.

In this in vitro study, 30 fresh extracted human molars were prepared to evaluate the tensile bond strength of endocrowns made by IPS e.max CAD, Vita Suprinity, and Vita Enamic blocks (n=10). The specimens were mounted and endodontically treated. Standard preparations were done with 4.5±0.5 mm intracoronal extensions into the pulp chamber and the restorations were designed and milled by CAD-CAM technique. All specimens were cemented with a dual polymerizing resin cement according to the manufacturer's instructions. The specimens were incubated for 24 hours and then thermocycled for 5000 cycles at 5-55°C and underwent the tensile strength test by universal testing machine (UTM). Shapiro-Wilk and one-way ANOVA test were used to statistically analyzed (α= 0.05).

The highest tensile bond strength values were achieved in IPS e.max CAD (216.39 ±22.67N) and Vita Enamic (216.22±17.72N) followed by Vita Suprinity (211.54±20.01N). There was no significant statistical difference between retention of endocrowns made by CAD-CAM technique among ceramic blocks (p= 0.832).

Within the limitation of this study, there was no significant difference between retention of endocrowns made by IPS e.max CAD, Vita Enamic, and Vita Suprinity as ceramic blocks.

 Considering the increased use of preheating and novel resin-based materials to restore teeth, the present study investigated the impact of preheating on the flexural strength of a giomer and compared it with a nanohybrid composite resin.

Two restorative materials (Beautifil II giomer and Alpha III nanohybrid composite resin) were used. Thirty rod-shaped samples (adding up to 60 samples) were prepared from the materials above and divided into two subgroups: with and without preheating (n=15). Before sample preparation, the giomer and nanohybrid composite resin tubes were preheated at 68ºC for 15 minutes in the preheating subgroups. In the subgroups without preheating, the tubes were kept in a room at 25ºC. Then the flexural strength was compared between the two groups with two-way ANOVA at a significance level of P<0.05.

The results showed significantly higher flexural strength in the preheated subgroups than in the non-preheated subgroups (P<0.001). In addition, the mean flexural strength values were significantly higher in the giomer groups than in the nanohybrid composite resin groups (P<0.001).

Preheating increased the studied materials’ flexural strengths significantly. The flexural strength of the giomer restorative material was higher than that of the nanohybrid composite resin, irrespective of preheating.

The present study aimed to evaluate the antibacterial agents of composite resin materials, their efficacy in caries prevention, and their impact on the mechanical properties (flexural strength) of composite resin restorative materials.

In this systematic review and meta-analysis, all published articles on the effects of antibacterial properties of composite resin materials in the prevention of dental caries (between 2005 to 2020) were evaluated using valid databases, including PubMed, Google Scholar, Web of Science, ISI, Scopus, Cochrane, ProQuest, and Embase, found by searching the keywords “anti-bacterial agents,” “composite resins,” “dental restoration,” and “dental caries” according to the MeSH system. The context of the studies was extracted and subjected to modified CONSORT. The required data were extracted and analyzed with the Comprehensive Meta-Analysis software.

According to the results of the random effect model, the heterogeneity of biofilm colony forming unit (CFU) average was -1.90 (CI: -1.68 to -2.13). The mean value of the control group was higher than the intervention. The heterogeneity of flexural strength (FS) average was -11.92 (CI: -8.30 to -15.55). The mean value of the control group was higher than the intervention group. The heterogeneity of thiazolyl blue tetrazolium bromide (MTT) absorbance average was -0.90 (CI: -0.65 to -1.14). The mean value of the control group was higher than the intervention group.

The results of the present study showed that the antibacterial agents had a significant effect on the caries prevention properties of the composite resin materials; however, due to the bias related to different control groups, laboratory conditions, and mismatch between in vitro and in vivo conditions, more studies are needed in this regard.

Many adult patients requiring orthodontic treatment have posterior restorations. Bracket bonding to dental restorations is a clinical challenge. The aim of this study was to compare the effect of universal adhesive with the conventional method on shear bond strength (SBS) of orthodontic brackets to amalgam restorations.

Ninety cavities were filled with admixed amalgam and divided into six groups (n=15) according to the surface pretreatment (nomechanical preparation, diamond bur preparation, and sandblasting) and type of bonding agent (alloy primer plus Transbond XT or universal adhesive). Mandibular central incisor brackets were bonded to the restoration surfaces. The primary outcome was the bond strength in megapascals (MPa) which was compared by two-way ANOVA. The mode of failure was the secondary outcome determined by determination of the adhesive remnant index (ARI). The Kruskal-Wallis and Mann-Whitney tests were used to compare the ARI scores among the groups.

Among the groups with the conventional method, the sandblasted subgroup showed the highest SBS (P<0.05). The three subgroups of universal adhesive were not significantly different in terms of SBS (P=1). Overall, the highest SBS was noted in the sandblasted/conventional adhesive group.

The results demonstrated that sandblasting plus alloy primerand Transbond XT bonding agent could be recommended for bracket bonding to amalgam restorations. Further studies using other bonding agents are recommended.

This study aimed to compare the marginal fit of temporary restorations fabricated by the conventional chairside method, 3D printing, and milling.

In this in vitro, experimental study, 14 temporary restorations were conventionally fabricated over an implant abutment and analog that had been mounted in a phantom model at the site of canine tooth, using auto-polymerizing acrylic resin and putty index. In digital manufacturing, the original model was scanned, and the final restoration was designed. Fourteen temporary restorations were milled out of polymethyl methacrylate (PMMA) blocks, and 14 others were printed by a 3D printer. Temporary crowns were placed on the abutment, and images were obtained from specific areas under a stereomicroscope at x100 magnification to measure the amount of marginal gap. Data were analyzed using one-way ANOVA and Tukey’s test (α=0.05).

The mean marginal gap values for the temporary crowns in the 3D printing, milling, and chairside groups were 91.40, 75.28 and 51.23 µm, respectively. The crowns that were conventionally fabricated chairside exhibited the lowest marginal gap, and the difference in this respect was significant among the three groups (P<0.05).

Temporary crowns fabricated by the chairside method showed significantly smaller marginal gap; however, the marginal gap of all three groups was within the clinically acceptable range.

Bulk fill composites are preferred to conventional composites with time-consuming incremental application technique, given that they have good mechanical properties and low microleakage. The aim of this study was to evaluate and compare the dentinal marginal microleakage of bulk fill (in two viscosities) and conventional composites in class II cavities in maxillary premolars.

In this in vitro studyˏ 42 class II cavities were prepared in the mesial and distal surfaces of 21 maxillary premolars extending 1 mm below the cementoenamel junction, and restored with Grandio composite with 2-mm increments, and X-tra fil and X-tra base with 4-mm increments. After 24 h of storage at 37oC and 100% humidity, they were thermocycled (500 cyclesˏ 5-55oC), stored in basic fuchsine, sectioned, and evaluated under a stereomicroscope (×40). The microleakage scores of the gingival margin were recorded. Statistical analysis was done by SPSS 21 via the Kruskal-Wallis and Mann-Whitney U tests at P≤0.05 level of significance.

No statistically significant differences were noted among the groups in marginal microleakage (P=0.47). No statistically significant difference was noted between bulk and incremental application techniques in this respect either (P=0.23).

There was no difference in marginal microleakage between the bulk fill and conventional composites.

Considering the ever-increase use of vital bleaching procedures and an increase in the use of newly introduced resin-based materials for the restoration of teeth, this in vitro study was designed to evaluate the effect of 15% carbamide gel on the flexural strength of three resin-based restorative materials.

Three different types of restorative materials, Beautifil II giomer, Cention N and Z250 micro-hybrid composite resin, were evaluated in the current study. Twenty-four bar-shaped samples were prepared from each restorative material, totaling 72 samples, and randomly assigned to two groups: with and without bleaching procedures (n=12). In the groups with a bleaching procedure, 15% carbamide peroxide gel was applied 8 hours a day for 14 days. The flexural strengths of the samples were determined. Two-way ANOVA and post hoc Tukey test were applied to compare the flexural strengths of the samples.

There were significant differences in the flexural strengths of the materials in terms of the exposure to the bleaching agent (P<0.05), with significantly higher flexural strength in the groups without a bleaching procedure. However, the mean flexural strengths were not significantly different in terms of the restorative material (P=0.12).

It was concluded that 15% carbamide peroxide bleaching gel significantly decreased the flexural strengths of Beautifil II giomer, Cention N and Z250 micro-hybrid composite resin. There were no significant differences in the mean flexural strengths between the three resin-based restorative materials, irrespective of the use or no use of 15% carbamide peroxide gel.

This in-vitro study aimed to evaluate the effect of cavity disinfection with chlorhexidine (CHX) on marginal gaps of Class V composite resin restorations bonded with a universal adhesive using self-etch and etch-and-rinse bonding strategy.

Sixty sound human premolars were randomly assigned to two groups (n=30): group 1 (CHX) and group 2 (no CHX). Each group was divided into two subgroups (n=15) according to the bonding strategy of the universal adhesive (self-etch or etch-and-rinse). Class V cavities were prepared on the buccal surfaces of the teeth. The occlusal and gingival margins of the cavities were placed in enamel and dentin, respectively. In the first and second subgroups of both groups, the All-Bond Universal adhesive was applied with self-etch and etch-and-rinse bonding strategy, respectively. After restoration and thermocycling, the samples were sectioned, and marginal gaps at the gingival margins were measured in micrometer (µm) under a stereomicroscope. Two-way analysis of variance (ANOVA) was used to compare marginal gaps between the groups and the subgroups.

The mean marginal gap size was significantly affected by cavity disinfection (P=0.001) and bonding strategy (P=0.002). However, the interaction effect of these two factors on the mean marginal gap size was not significant (P=0.79).

The use of CHX resulted in larger marginal gaps at the gingival margins of Class V composite resin restorations. Irrespective of disinfection, the self-etch bonding strategy resulted in larger marginal gaps compared to the etch-and-rinse bonding strategy.

It has been reported that bulk-fill composites simplify tooth restoration with no adverse effect on the success rate. This study sought to assess the cuspal deflection of premolars with mesio-occluso-distal (MOD) cavities restored with bulk-fill and conventional posterior composite resins.

This in-vitro experimental study was conducted on 64 human maxillary premolars. MOD cavities were prepared on teeth and restored with Filtek P60 conventional composite and Filtek Bulk Fill flowable, X-tra fill, and X-tra base bulk-fill composites in four groups (n=16). Distance between the cusp tips was measured before, five minutes, 24 hours, 48 hours, and one week after restoration. The data were analyzed using repeated-measures analysis of variance (ANOVA) and Tukey’s test (α=0.05).

The mean±standard deviation (SD) of cuspal deflection at five minutes after the restoration was 13.5±5.3, 12.2±3.5, 11.3±4.4, and 10.4±3.7 µm for Filtek P60, Filtek Bulk Fill, X-tra fill, and X-tra base, respectively. ANOVA showed that bulk-fill composites did not cause a significant reduction in cuspal deflection compared to P60 (P>0.05). Cuspal deflection in all groups significantly decreased with time (P<0.05).

Bulk-fill composites have no superiority over P60 in the reduction of cuspal deflection. The cuspal deflection was variable at different time points in all groups and decreased over time.

Immediate implant placement has advantages such as time saving, optimal soft tissue architecture preservation and patient acceptance. In this case prior to implant placement, minimal guided bone regeneration was performed to augment the concavity on the apico-labial aspect of fractured maxillary right lateral incisor. After 8 months this tooth was extracted and an implant immediately inserted and provisional composite based crown was delivered in the same appointment. After 4 months well molded mid-facial gingiva and inter-proximal papilla were obtained and definitive metal ceramic crown was fabricated.

The purpose of this study was to evaluate the bond strength between two porcelains (VITA VMK Master and VITA VM13) and two types of base metal alloys (Ceramill Sintron and Verabond).

In an experimental study, 20 rectangular strips (25 mm × 4 mm × 0.5 mm) of each base metal alloy (Ceramill Sintron and Verabond) were fabricated according to the manufacturer’s instructions. After sandblasting and polishing, the samples were placed in an ultrasonic device to remove surface contaminants. A surface of 8 mm × 4 mm × 1 mm of samples was veneered with Vita VM13 and VITA VMK Master. The samples were divided into four groups (n = 10 each group; VM13/Ceramill, VMK Master/Ceramill, VM13/Verabond, and VMK Master/Verabond), and bond strength was evaluated by three‑point bending test with a universal testing machine. Two‑way ANOVA was used for comparison in each group, post hoc Scheffe’s test was used for analyzing data between groups, and the Kolmogorov–Smirnov test was used for the normality (P < 0.05).

The maximum bond strength was related to Verabond/VM13 (44.35 ± 7.9 MPa) and then the Ceramill Sintron/VM13 (39.33 ± 4.43 MPa), and the lowest was related to the Ceramill Sintron/VMK Master (29.75 ± 3.2 MPa). There was no significant difference between bond strength of VM13 with the two alloy groups (P > 0.05), and bond strength of VMK Master to Ceramill Sintron CAD/CAM alloy was less than the conventional Verabond alloy (P < 0.05); however, bond strength of all the groups was above the standard threshold (25 MPa).

Based on the results of this study, the bond strength of the porcelain to Verabond was better, but the bond strength of the porcelain to Ceramill Sintron also was not less than the standard threshold; thus, this new CAD/CAM alloy can be an alternative to the conventional base metal alloys in the metal‑ceramic restorations.

This study aimed to evaluate the child’s salivary cortisol levels, clinical performance and marginal adaptation of restorations after selective removal of necrotic dentin in primary teeth using Er: YAG laser irradiation. A double-blind clinical study was performed in children at 7-10 years. Children who had at least 2 teeth with carious lesions involving the occlusal and proximal surfaces of primary molars counterparts were selected. Removal of necrotic dentin was performed by 2 methods Er: YAG laser irradiation and bur-preparation. Cortisol levels (n = 24) was evaluated by ELISA. Clinical analysis (n = 20) was performed after the restorations polish, 6 and 12 months after restorative procedure using United States Public Health Service (USPHS) method and photographs. Scanning electron microscopy (SEM) was used to analyz the marginal gap formation (n = 20). The analysis of the data was performed by 95% confidence interval, Shapiro-Wilk test, Friedman and Wilcoxon post hoc tests (α = 5%). Cortisol levels were higher during selective removal of necrotic dentin, regardless of the method used (P > 0.05). After 12 months, there was no evidence of the difference in the restorations performed on cavities prepared by both methods. SEM analysis revealed that the laser-irradiated teeth showed 10% of gaps in the full extent of restoration. For bur-prepared teeth, 20% of gaps were found at the cavosurface margin. The salivary cortisol levels on children that received Er: YAG laser irradiation for removal the necrotic dentin was similar to the control group. Class II restorations evaluated after 1 year period did not suffer interference by the use of Er: YAG laser irradiation.

 This study aimed to assess the distribution and classification of restored primary molars according to the tooth type, gender, jaw, quadrant, filling material and G.V. Black classification in children presenting to the Department of Pediatric Dentistry, College of Dentistry, and University of Baghdad.

In this retrospective study, 1,341 patient records were retrieved from the archives of the Department of Pediatric Dentistry and reviewed for the presence of restored primary molars. If present, they were classified according to the tooth type, gender, jaw, quadrant, filling material, and G.V. Black classification. Data were statistically analyzed by SPSS version 24 using z-statistic, with 0.05 level of significance.

The frequency of filled primary second molars was significantly higher than that of primary first molars. The frequency of filled primary molars was the same in males and females. The frequency of restored primary molars in the mandible was significantly higher than that in the maxilla. Also, the frequency of restored primary molars in the right side was higher than that in the left side; however, this difference was not significant. According to the type of filling material used, amalgam was the most frequently used filling material followed by composite with no significant difference. According to the G.V. Black classification, class II had the highest percentage, followed by class I but the difference was not significant. Class V had the lowest percentage.

The current findings regarding the filled primary molars provided baseline data for future achievements in the respective department and comparisons.

Coronal restoration could affect the setting reaction of the underlying CEM cement. The aim of the present study was to evaluate the effect of immediate coronal restoration placement on the subsurface microhardness of CEM cement. Methods and Materials: In 50 extracted human mandibular molars, access cavities were prepared and CEM cement was placed in the pulp chamber at a 3-mm thickness. Samples were divided into ten groups (n=5). CEM cement was placed and after 10 min, two groups were restored with Zonalin temporary restoration and eight groups were restored with glass ionomer cement (GIC), resin modified glass ionomer (RMGI), resin based composite and amalgam respectively. Vickers microhardness number (VHN) of CEM cement was measured in two time intervals (7- and 21-days). Data was analyzed with SPSS and two-way analysis of variance and Bonferroni tests. Level of significance was set at the 5%. The mean VHN of CEM cement showed statistically significant differences only between Zonalin and amalgam groups (P=0.021). There were also significant differences considering the effect of time (P=0.042) and material (P=0.046). Although the effect of time-material on the microhardness values showed no statistically significant differences (P=0.636). Based on the results of the present study, immediate placement of final restorations affects the setting reaction in underlying CEM cement. Therefore, sufficient moist curing and hydration should be guaranteed before the placement of the coronal restoration.