فهرست مطالب
Journal of Dental Materials and Techniques
Volume:9 Issue: 3, Summer 2020
- تاریخ انتشار: 1399/08/22
- تعداد عناوین: 8
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Pages 107-115IntroductionHigh fracture resistance of prostheses are well accepted by both patients and dentists to have a proper restoration of the dentition. The research designated assess polymerization time effect distinct and complete temperatures on mechanical properties (denture base resin) of a high strength. The research purpose is to assess and compare the procedure used in polymerization distinct effect autoclave on the elastic modulus and transverse strength of a high strength acrylic resin to the conventional heat polymerizing.MethodsRectangular sample of ninety-one polymarised high heat strength denture base resin were created. Polymerized sample done by hot water regarded as control group and the other groups were polymerized in autoclave at different temperatures and time lenghts. After deflasking of sample before procedure it was kept forty eight hours in water. Three parameters were used when conducting transverse strength test bending using calibrated universal testing machine with a load of 500 kg cell and a crosshead speed of 5 mm/min. One-way ANOVA was used in assessing transverse strength and elastic modulus data. And for comparison of the groups application of Tukey HSD trial has been seen appropriate (p <0.05).ResultsSpecimens that polymerized by autoclave at 130ºC for 20 and 30 minutes showed significantly better characteristics compared to the other groups.ConclusionUpgrading of base resins transverse strength is required because the research indicated autoclave polymerization at 130°C for 20 and 30 minutes may be an alternative polymerization method.Keywords: Acrylic resins, Polymerization, Elastic modulus
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Pages 116-122IntroductionUnderstanding the variations in the thickness of facial soft tissue is important in forensic medicine, dentistry, and plastic surgery. This study aimed to evaluate the thickness of the facial soft tissue in adolescents with different maxillary skeletal patterns and compare them between both sexes, by using digital lateral cephalometric radiographs.Methods97 patients over 18 years of age referring to a private radiology center for digital lateral cephalometric radiographs participated in this study. Standard digital lateral cephalometric radiographs of patients were categorized based on the ANB angle to three Skeletal jaw classes ( I, II, and III). Then, in each of the lateral cephalometric radiographs, the Soft tissue landmarks including glabella, nasion, subnasale, labrale superius, stomion, labrale inferius, labiomental, pogonion, menton, and the vertical distance of each landmark to the bone surface were determined. Soft tissue thickness landmarks at each site were measured separately in males and females and in three different skeletal class groups. Statistical analysis of multivariate multiplicative variance was used to compare the data.ResultsThe results of the study showed that soft tissue thickness in Glabella and Labiomental points were not significantly different between men and women (P-value >0.05). Other landmarks in men were significantly higher than women(P-value<0.05). As for the relationship between soft tissue thickness and skeletal classes, subnasale, labrale superius, stomion, labrale inferius had significant association with skeletal classification (P-value<0.05).ConclusionThese findings point to the importance of sex and cranial morphology in soft facial tissues for accurate facial reconstructionKeywords: Thickness of facial soft tissue, Skeletal jaw classes, Lateral cephalogram
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Pages 123-129Introduction
Mechanical debridement of diseased root surfaces produces a smear layer that encompass microorganisms and residual cementum which may interfere with periodontal healing and regeneration of connective tissue attachment. Accordingly, this study aimed to determine impact of 940nm diode laser on adhesion of fibroblasts to root surface of extracted teeth from patients with chronic periodontitis.
MethodsTwenty extracted single-rooted teeth with hopeless prognosis were collected and debrided with hand curettes. Afterward, two specimens were obtained from each tooth by splitting them with a sterile diamond disk. Samples were submerged in fibroblast suspension and randomly divided into two groups. Group A comprised of 20 specimens subjected to scaling and root planing only and group B included 20 specimens which received SRP and and 940 nm diode laser irradiation. The adhesion of fibroblasts was investigated by MTT and cell morphology was assessed with scanning electron microscopy (SEM).
ResultsThe extent of adhesion was higher in group B compared with group A, though this difference was not statistically significant. In the laser group, fibroblast cells showed more elongated morphology and a smaller number of rounded forms was found. But no significant difference was observed between the two groups.
ConclusionA diode laser with a wavelength of 940 nm has a negligible effect on adhesion of fibroblasts to the root surface of teeth extracted because of chronic periodontitis
Keywords: chronic periodontitis, Diode laser, laser(s), Fibroblast(s), Root planing -
Pages 130-138IntroductionThis study aims to evaluate surface wettability of additional silicone impression materials, which are immersed in different disinfecting agents with different time intervals.MethodsNinety disk-shaped specimens to be eighteen specimens from each of five different impression materials (four vinyl polysiloxane and one vinyl polyether siloxane) were prepared. The specimens were divided into six groups according to the disinfecting agents (one of them containing ethanol and other one containing benzalkonium chloride) and periods. Then, the specimens were immersed in two disinfecting agents for 1 minute, 1 hour and 24 hours. Later, surface wettability was tested and recorded. Data were analyzed with analysis of variance (ANOVA).ResultsThere was no difference between impression materials and disinfectants in terms of the effect on the contact angle (p>0.05), and there was a significant difference between disinfection times (p=0.001).ConclusionsOne-minute disinfection process increases wettability of specimens compared to long term disinfections.Keywords: Additional silicone, Contact angle, disinfection, wettability
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Pages 139-146Introduction
Refractory root canal infection is mostly associated with enterococcus faecalis. The chemomechanical cleaning of root canal is one of the most critical steps in endodontic treatment. Intracanal medicaments are used as a supplementary disinfection process. Essential oils are rich in antibacterial properties and can be used against bacteria in root canals.Aim of this study was to evaluate antimicrobial activity of 5 essential oils mixed with calcium hydroxide against E.faecalis
MethodsEnterococcus faecalis (ATCC 29212) was assigned as test organism, inoculated into Brain heart infusion broth, incubated overnight at 370 C and subcultured onto Brain heart infusion agar. 4 cup wells of 10 mm diameter were bored in each petriplate. These wells were then filled with freshly prepared test medicaments and incubated for 24 hours in upright position. The zones of inhibition were analyzed and diameters were measured using a ruler.
ResultsThe mean zone of inhibition was significantly higher among Geranium oil + Ca(OH)2, Lemon grass oil+ Ca(OH)2, Rosemary oil+ Ca(OH)2 and Saline + Ca(OH)2 when compared to Jojoba oil +Ca(OH)2 and Almond oil+ Ca(OH)2.
ConclusionCalcium hydroxide combined with essential oils can be used as an effective intracanal medicament against E.faecalis.
Keywords: Essential oils, Antimicrobial, E. faecalis, Zone Of Inhibition -
Pages 147-151IntroductionThe Aim of endodontic treatment is to remove infection and prevent recontamination of root canal system. Endodontic sealers are used to fill irregularities that are inaccessible for core filling material. Their penetration into dentinal tubules is of great importance to obtain a better seal. Sealers with nanoparticles may have a deeper penetration because of their smaller particles. The purpose of this study was to compare the penetration ability of a new nanoparticle sealer with two other sealers.MethodsTwenty single-rooted premolars were decoronated and prepared using NeoNiTi rotary files. Then the smear layer was removed and canals were randomized in three groups and filled with gutta-percha. Nano-ZnO sealer, AH26, and Pulp Canal Sealers were used for each group. Teeth were sectioned at two levels (4 and 8 mm from the apex) and examined under a scanning electron microscope.ResultsThe results showed the deepest penetration for AH26 Penetration depth in the coronal section was deeper than apical. There was no significant difference between penetration depth of AH26 and Nano-ZnO sealer in the apical region, but AH26 showed significantly more penetration in coronal section.ConclusionAccording to the results of this study, Nano-ZnO sealer showed less penetrability compared to AH26 in coronal region of the roots.Keywords: AH26, Nano-ZnO sealer, Pulp Canal Sealer, scanning electron microscope, tubular penetration
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Pages 152-160Introduction
Short implants are considered as a sole option in many patients due to anatomical limitations. It was aimed to assess the functional load stress at implants, surrounding bone and superstructures with different inclination angle.
MethodsSeven finite element models with three implants (4 mm × 8 mm) and a separate model with longer implants (4 mm× 10 mm) with an angulation of 37° were designed. The implants were first placed vertically and then angled in distal direction preserving their parallelism increasing 6 ° at each step. Chromium-Cobalt was used to prepare superstructures. Oblique force of 100 N was applied on superstructures.
ResultInclined implant replacement did not significantly increase stress and compressive forces on bone, and the stress on implant surrounding bone decreased as inclination angle increased. On the other hand, in the model with linger implant more homogenous stress distribution was observed and implant’s von Mises values decreased.
ConclusionInclination of implants could have no detrimental effects on bone. Furthermore, inclination of implants provides the opportunity of placing longer implants and also more favorable stress distribution around the implants and in bone.
Keywords: Finite element analysis, dental implant, Fixed Partial Denture, Implant Inclination, Stress analysis -
Pages 161-170Introduction
The aim of this experimental in-vitro study was to evaluate and compare marginal accuracy of interim restorations made with three chemically different interim materials one hour after fabrication and at one week interval.
MethodsTwenty samples from each group with a total of sixty were fabricated on a customized metal die. The three test groups were as below; Group A - Protemp TM 4 (3M ESPE AG Dental Products, Germany), a bis-acrylic based self-cure temporary material; Group B - Revotek LCTM (GC Dental Products Corp., Japan), a urethane dimethacrylate based light cure temporary material and Group C - Tuff-Temp™ Plus (Pulpdent Corporation, U.S.A), a rubberized-urethane based dual cure temporary material. All samples were stored in artificial saliva and evaluated for marginal discrepancy using a stereomicroscope, one hour and one week after fabrication. Statistical analysis was done using one way ANOVA test and Tukeys Post-hoc tests.
ResultsStatistical significant difference existed between three groups after one hour (p <0.001) and after one week (p <0.001), Tuff-Temp™ Plus showed the least marginal discrepancy (at one hour =192.3± 0.75µm; at one week = 242.69 ± 5.64µm), while Revotek LCTM (at one hour = 232.52± 0.48µm; at one week = 293.68 ± 3.75µm) had the highest discrepancy.
ConclusionsTuff-Temp™ Plus showed higher marginal accuracy followed Protemp TM 4 and Revotek LCTM at one hour and one week interval.
Keywords: marginal accuracy, provisional restoration, interim crown