Showing 88 results for Rat
Marzieh Alikhasi, Pooya Aslani,
Volume 26, Issue 2 (5-2013)
Abstract
Background and Aims The purpose of this study was to evaluate the survival rate, mean bone loss and post operative complication of implants inserted in All-on-4 technique .
Materials and Methods: The literature was searched using keywords angled implant, All-on-4, tilted implant and graftless technique in the last 10 years (2001 to 2011) and clinical trial article that evaluated survival rate and mean bone loss around axial and tilted implants in All-on-4 technique was selected and evaluated. A total of 73 articles were found by searching. After evaluation of titles and abstracts, finally 10 clinical trial, that were fully consistent with including criteria such as mean of bone loss and survival rate was selected and evaluated.
Conclusion: Results showed that the survival rate (96-100%) and mean bone loss (0.34-1.9 mm) with All-on-4 technique in immediate loading is comparable with other implant support treatment plan. Comparison of implant survival and bone loss in axial and tilted implant in All-on-4 system is shown this treatment plan has consistent result with other conventional implant support prosthesis. Also, postoperative complication including fractures of the acrylic temporary prosthesis, detachment of the teeth, abutment or prosthesis screw loosening have been reported with All-on-4 technique.
Davari Abdolrahim , Kazemi Alireza Danesh , Mousavinasab Majid , Mohammadi Najmeh Pour ,
Volume 26, Issue 3 (8-2013)
Abstract
Background and Aims: Different adhesives with different solvents may have different solvent evaporation rates. The purpose of this study was to evaluate the solvent evaporation in the self etch and total etch adhesive in different air drying times.
Materials and Methods: Five adhesives were used in this study: Excite, Prime & Bond NT, UNO, Single Bond, SE Bond Primer. Twelve drops of each adhesive were used for each period of air drying (5, 15, 30 sec). The percentage of mass loss was measured during each test. Data were analized using two-way ANOVA and Tukey.
Results: Acetone base adhesives showed more loss of mass than other adhesives (P<0.01). P&B NT showed more loss of mass than other adhesives in all air drying times (P<0.01). Adhesives showed different evaporation rates in different air times (P<0.01).
Conclusion: Adhesives with acetone/water or alcohol/water solvent shows more stable behavior in comparison with adhesives containing pure aqueous solvents.
Reza Yazdani, Hamide Kalkou, Mohammadreza Khami ,
Volume 26, Issue 3 (8-2013)
Abstract
Background and Aims: Iatrogenic damage to adjacent tooth during proximal cavity preparation is one of the most common side effects in operative dentistry. The aim of this study was to determine prevalence of iatrogenic damages to adjacent tooth during the preparation of proximal Class II cavities among undergraduate students at dental faculty of Tehran University of Medical Sciences in 2010 .
Materials and Methods: 106 posterior permanent teeth which had Class II decay with sound proximal surfaces of adjacent teeth were selected and restored by dental students awarding the aims of the present study. After finishing restoration, proximal surfaces were completely dried by air and evaluated with dental chair light. In doubtful cases, surfaces were evaluated with × 3 magnification. Damages were classified into 2 groups abrasion and groove. Data were analyzed using Fishers exact and Pearson chi square tests .
Results: The frequency of adjacent surfaces damage were 57.5%, with 31.1% damages as abrasion and 26.4% as groove. Students who used matrix band and wedge in proximal area as preventive instruments showed 53.4% damages and other students showed 57.3% damages (P>0.05). A significantly higher number of females and students at restorative course level (3) used wedge and matrix band than males and students at restorative course level (4) for protecting adjacent teeth (P<0.05).
Conclusion: According to the high percentage of iatrogenic damages on adjacent sound teeth in class II cavity preparation, teaching of preventive methods and using proper techniques is necessary for dental students as future dentists.
Mahmod Kazemi, Saeed Nokar, Ahmad Rohanian, Adel Pazhohan,
Volume 26, Issue 4 (1-2014)
Abstract
Background and Aims: Thermal changes in the oral cavity can be transferred to the implants placed in bone and affect the prognosis of the treatments. Furthermore, some investigators proposed improvement of habitual consumption of hot or cold beverages. The aim of the present study was to measure the effect of temperature changes in the oral cavity following consumption of hot and cold drinks on the temperature of implant.
Materials and Methods: In this clinical trial, 3 eligible patients were selected. Two months after implant insertion, temperature of the implants was measured following the drinking of hot and cold beverages using a sensor connected to a thermometer. The thermal changes of the implants through the different time intervals were analyzed using Friedman non-parametric test.
Results: The implant temperatures were significantly increased in the time following drinking of the hot beverages (P=0.009). Furthermore, the implant temperature were statistically decreased in the time after drinking cold beverage (P=0.004). When drinking hot beverages, the maximum and minimum temperatures were 41.57 0 C and 36.77 0 C, respectively. The maximum and minimum temperatures of the implants were also 34.13 0 C and 26.83 0 C , respectively, when drinking cold beverages.
Conclusion: It seems that the temperatures noted in the implants in the current study cannot weaken the prognosis of implant restorations however, habitual consumption of hot and cold beverages can lead to debilitating implant prognosis and therefore, should be given the necessary warnings to patients.
Narges Dorri, Azita Kaviani, Ali Noori,
Volume 27, Issue 2 (6-2014)
Abstract
Background and Aims: The ability of composite restorations to prevent microleakage needs desirable bonding material for proper sealing . The purpose of this study was to evaluate class V composite restorations microleakage in premolars with/without electric current while applying variant dentin bonding in vitro.
Materials and Methods: 120 non-carious human premolars were used for this study and standardized class v cavities were prepared. The tooth roots were cut by discs at a distance of 5 mm from CEJ and pulp tissue was removed. The teeth were divided into six groups of 20. In the first group, electric current was applied, Single bond (3M ESPE, St Paul, MN, USA) with a broom motion attached to the cathode and a sponge containing bonding was used as anode. The used current was 15µA and the Single bond in the second group was used without electricity. Then two bondings PQ1 (Ultradent, Germany) and Optibond solo plus (Kerr, USA) were used with and without electricity. After adhesive application and curing the bonding agents, cavities were restored by a composite (Valux Plus). The root ends were sealed by wax and all teeth surfaces, except 1 mm around the restorations were covered with a nail varnish. The specimens were thermocycled for 1000 cycles and placed in fushin for 24 hours and were then sectioned vertically and examined under a stereomicroscope. Data were scored on a 0-4 scale based on microleakage at the gingival margins and analyzed using Kruskal-Wallis and Mann-whitney test.
Results: Based on the results, the extent of microleakage in the groups of electric current was significantly less than the groups without using the electric current (P=0.05). The lowest degree of microleakage was found in PQ1 group, and the greatest difference between the groups with and without electricity was also found in PQ1 group. Single bond and Optibond Solo Plus with electric current showed a lower degree of microleakge.
Conclusion: The result showed that use of electric current during the application of dental adhesives could reduce the extent of microleakage.
Farzaneh Jabari, Javad Mohammadnejad, Kamal Yavari,
Volume 27, Issue 3 (9-2014)
Abstract
Background and Aims: In the last decade, several studies have reported the isolation of stem cell population from different dental sources, while their mesenchymal nature is still controversial. The aim of this study was to introduce the isolating methods for stem cells from human dental pulp and to determine their mesenchymal nature before differentiation.
Material and methods: One of the best sources for stem cell is dental pulp tissue. Dental Pulp Stem Cells (DPSCs) would be the most convenient source of stem cells because teeth were easy to retrieve and removed throughout life. Pulp is a specialized connective tissue including blood and lymph vessels, nerves, and the interstitial fluid. DPSCs can be found within the ‘‘cell rich zone’’ of pulp. DPSCs have been isolated for the first time in 2000 by Gronthos these cells exhibited a differentiation potential for odontoblastic, adipogenic and neural cytotypes. Gronthos isolated stem cells in 2 different methods: The enzymatic digestion method and the second was out growth, these cells could be cryopreserved in liquid nitrogen. It has also been shown that human DPSCs can be used for complex structures such as pulp or woven bone formation in vivo.
Conclusion: DPSCs originate from the cranial neural crest and have neural characteristics such as the expression of neurotrophins. Therefore, DPSCs may represent a promising source in cell therapy for neurological disorders. Characterization of these cells and determination of their potentialities in terms of specificity of regenerative response will form the foundation for development of new clinical treatment modalities, whether involving directed recruitment of the cells and seeding of stem cells at sites of injury for regeneration or use of the stem cells with appropriate scaffolds for tissue engineering solutions. Such approaches will provide an innovative and novel biologically based on new generation of clinical treatments for dental disease.
Davari Abdolrahim , Daneshkazemi Alireza , Modaber Maryam , Malekzadeh Mohammad ,
Volume 27, Issue 4 (1-2015)
Abstract
Background and Aims: The most effective preventing tooth decay method is fluoride compounds applications. Some studies suggested that APF gels caused changes on the superficial physical properties of composite. Therefore, the purpose of this study was to evaluate the marginal microleakage of class V composite restorations before and after AFP gel application.
Materials and Methods: The class V cavities in buccal surfaces of 45 molar teeth were made in such a way that occlusal margin was placed in enamel and cervical margin in cement. In group 1, at first fluoride-therapy and then cavity preparation and restoration by composite resin was done. In group 2, at first the class V cavities were prepared and restored, then fluoride-therapy was carried out. In group 3, cavities were prepared and restored with no fluoride-therapy. The dye penetration rate in occlusal and cervical margins was examined by stereomicroscope. Data were statistically analyzed using Kruskal-Wallis and Mann-Whitney test.
Results: There was no statistically significant difference between groups ( P=0.975).
Conclusion: Fluoride-therapy using AFP gel before and after class V composite restorations, had no significant effect on the microleakage of dentin and enamel margins.
Feizi Ghader , Kaviani Naser , Mehrparvar Roza , Binandeh Elham Sadaat , Tabrizizadeh Mehdi , Saatchi Masoud ,
Volume 27, Issue 4 (1-2015)
Abstract
Background and Aims: Postoperativee endodontic pain is an outstanding problem for dental patients. Therefore, a successful management of endodontic pain has become as one of the main dental objectives. The aim of the present study was to compare the postoperative endodontic pain in patients under general anesthesia versus local anesthesia.
Materials and Methods: For conducting this clinical trial study, 50 patients having mandibular molars candidate for root canal therapy were selected. Twenty-five patients treated under general anesthesia because of their fear, anxiety or gag reflex. Other 25 patients treated under local anesthesia. All teeth were prepared using engine-driven rotary system in a crown-down technique and filled using lateral condensation technique. Heft- parker visual analog scale was used to measure the degree of pain at 6, 12, 24, and 48 hours after the treatment. Mann-Whitney, Chi-square, and T-tests were used to compare the intensity of postoperative pain between the groups.
Results: The mean intensity of postoperative pain in local and general anesthesia groups at 6, 12 and 24 hours had statistically significant difference (P<0.05).
Conclusion: Postoperative pain in patients who treated under general anesthesia was significantly less than the patients who treated under local anesthesia.
Ezatollah Jalalian, Fatemeh Rajaei, Marzieh Bavaisi, Niloofar Moghaddam, Fereshte Keykha, Rezvaneh Cheraghi,
Volume 28, Issue 2 (7-2015)
Abstract
Background and Aims: Tooth crowning often leads to changes in periodontal index through changes in emergence profile zone. The purpose of this study was to compare the effect of metal-ceramic with that of
All-Ceramic restorations on the plaque a accumulation.
Materials and Methods: In this clinical trial, we used 102 teeth covered with metal-ceramic and all-ceramic restorations. Before and after crowning, plaque index (PI) and gingival indexes (MGl) were measured. Data were analyzed using covariance (ANCOVA) test.
Results: Measured PI and MGI (Mean±SD) in PFM Group prior to crowning were (1.96±0.38) and (1.45±0.48), respectively. In metal-ceramic restorations group, six months after crowning, measured PI and MGI (Mean±SD) were (1.22±0.49) and (1.82±0.61), respectively. Measured PI and MGI (Mean±SD) in All-Ceramic Group prior to crowning were (1.22±0.52) and (1.25±0.29), respectively. In All-Ceramic, six months after crowning, measured PI and MGI (Mean±SD) were (0.88±0.51) and (1.43±0.50), respectively. ANOVA test showed statistical significance difference between metal-ceramic and All-Ceramic Groups in Indexes (P<0.001).
Conclusion: Metal-ceramic and All-Ceramic crowns were associated with inflammatory changes in gingival. Metal-ceramic restorations were associated with higher inflammatory indexes compared with All-Ceramic crowns.
Mohammad Ali Keshvad, Tabassom Hooshmand,
Volume 29, Issue 2 (11-2016)
Abstract
Resin-based composite restorative materials have a substantial share in dental treatments. Their esthetic has made them patients’ first choice as restorative materials. Marginal leakage is one of their problems which leads to recurrent caries and post-operative hypersensitivity. Our aim was to evaluate the theoretical and clinical methods that have been proposed in the dental literature. Around 50 articles from Pubmed, SCOPUS and google scholar were selected and categorized in 4 groups based on the selected keywords. All the studies discussed in this paper have emphasized that there is no way to eliminate the microleakage but it can be reduced by means of some approaches. On the other hand, due to the multifactorial nature and difference of oral environment and laboratory conditions, there isn’t any certain way to define precisely. It seems that there is an absolute need for more research in this field to make the relation of theoretical results and clinical findings possible.
Maryam Khoroushi, Mohammad Rabbani Khorasgani, Azam Aliasghari,
Volume 30, Issue 1 (6-2017)
Abstract
Background and Aims: Tooth decay has high prevalence in the world. The use of plant material for the prevention and treatment of this disease for various reasons is considered, due to the increasing resistance of bacteria to antibiotics, the high cost and adverse effects of some chemicals used in dentistry. This study was aimed to determine the antimicrobial effect of alcoholic extract of Pepper (Capsicum annuum) and eggplant skin and cap on the cariogenic streptococci.
Materials and Methods: In this study, the antimicrobial activity of ethanol extract of Capsicum annuum and eggplant skin and cap on the cariogenic streptococci, including Streptococcus mutans, Streptococcus sobrinus, and Streptococcus sanguis by microtitre plate method for MIC (Minimum Inhibitor Concentration) was performed. Data were analyzed by one-way analysis of variance using Prism 5 Graph Pad software.
Results: MIC for the Capsicum annuum and eggplant skin for Streptococcus mutans was 250 mg/ml (SD=0.052), and for the Streptococcus sobrinus and Streptococcus sanguis was 125 mg/ml (SD=0.027). The MIC for the cap eggplant for Streptococcus mutans and Streptococcus sobrinus was 500 mg/ml (SD=0) and for S. sanguis was getting 125 mg/ml (SD=0.159).
Conclusion: This study showed that the herbal extracts of Capsicum annuum and eggplant skin and cap had beneficially antimicrobial effects on all three strains of cariogenic streptococci.
Ahmad Jafari, Narges Gholizadeh, Rashid Ramezani, Hanie Emami Razavi, Shamsolmoulouk Najafi,
Volume 30, Issue 2 (8-2017)
Abstract
Background and Aims: Cancer is the second most common cause of death in developed countries. The goal of this study was to determine the important epidemiologic factors affecting diagnosis and survival rate of patients with laryngeal SCC, for prevention, control and increase longevity.
Materials and Methods: In this study, all the cases recorded at the Center of Cancer Office of the Iran Ministry of Health in Tehran between 2005-2009 were examined. From 513 cases, 279 that their follow-up was possible by phone or postal address were included in the study. Data collection were performed from questionnaire. The data were analyzed by SPSS version 20. The Kaplan Meier survival curves were utilized and, moreover, the corresponding influential factors were examined by using the Cox regression test.
Results: The mean age of patients were 61.1 years (SD=10.54). The gender of 92.1% of patients were male. The most widely used method for the treatment was a combination of three methods of surgery, radiation therapy, and chemotherapy. The overall five-year survival rate was 75.7% (SD=0.03). The gender, histological differentiation, and professional delay did not exhibit a statistical correlation with the survival rate (P=0.38, 0.14, 0.52), whereas the age and patient delay had a statistically significant relation with the survival rate (P=0.03, 0.07).
Conclusion: The survival rate was lower in older patients. Patient and professional delays were high, which need more attention for improving the quality of life.
Seyed Javad Ghazi Mirsaeid, Zahra Ganjipour,
Volume 30, Issue 2 (8-2017)
Abstract
Background and Aims: By measure of scientific publications, it is possible to present a real picture of scientific activities of a country. In this regard, based on joint work to achieve specific objectives that typically produce knowledge and scientific information, scientific and research cooperations are defined. Therefore, the purpose of this study was to analyze the scientific collaborations in Iranian dentistry articles in Scopus during 2010‐2014.
Materials and Methods: The population was Iranian dental articles which were indexed in Scopus during 2010‐2014. Finally, the results were presented in the format of tables and diagrams.
Results: The findings showed that scientific cooperations were increased in the field of dentistry during 2014-2010 in the Scopus. Tehran University of Medical Sciences had the most publications. The rate of index, degree and coefficient of collaboration during 2010-2014, were 4.23, 0.97 and 0.71, respectively with relatively high values. Most of the articles during the 2010-2014 were four, three, and five authored articles were the first, second and finally the third position of occurrence rate. Our data suggested that the lowest number of articles were related to articles with 9 authors or more.
Conclusion: According to the results of this study, it can be concluded that the Iranian prosperity of scientific publication in the field of Dentistry is growing. Furthermore, the results showed that the Iranian authors and researchers have tendency to scientific collaboration with other researchers in groups.
Abdolrahim Davari, Alireza Danesh Kazemi, Mehrrnaz Fallah Tafti,
Volume 30, Issue 4 (1-2018)
Abstract
Background and Aims: A suitable restorative material must have acceptable mechanical properties. The aim of this study was to evaluate the effect of conventional acidic drinks on the micro-hardness of two dental resins.
Materials and Methods: 48 samples of each of P60 and G-aenial composites were prepared and randomly divided into six groups: Coca-Cola, Fanta, yoghurt drinks, soft beer, Sprites and control groups. The study was in 3 steps: after one day in distilled water and after one day and one week of immersion in beverages per day
(6 hours). The Vickers micro-hardness was then evaluated. Finally, data were analyzed by, t-tests, ANOVA and Tukey tests.
Resultes: Comparing the results between the two groups, a significant difference between the two composite was found. After one day in the water, the average micro-hardness for P60 was of 27.12 (kgf/mm2) and 16.51 (kgf/mm2) for G-aenial amount and these differences were found statistically significant (P=0.0001). For the
6-hour maintenance interval, the average micro-hardness between P60 and G-aenial was statistically significant (P=0.0001). For 42 hours, the average micro-hardness ranged between P60 and G-aenial that were statistically significant (P=0.0004). The stiffness of the P60 composite after 42 hours’ storage in soft beer significantly decreased compared with the control group (P=0.03). G-aenial composite hardness after 42 hours of soaking in the Coca-Cola was reduced significantly compared to yogurt drinks (P=0.02).
Conclusion: As a result, the hardness of P60 composite was higher than that of G-aenial. The hardness of both composites reduced in acidic drinks after one week.
Abbasali Khademi, Seyed Amir Mousavi, Azizolah Moraditalab, Shirin Shahnaseri, Saber Khazaei, Reyhaneh Tajali,
Volume 31, Issue 1 (6-2018)
Abstract
Background and Aims: Microorganisms are the main cause of pulpal and periapical diseases. The most important failure factor is the lack of proper seals for the canal, resulting in microbial leakage. Therefore, the purpose of this study was to evaluate the sealing ability of ProRoot MTA and Bio MTA in canal obturation using fluid infiltration.
Materials and Methods: In this experimental study, 46 extracted mandibular premolar single canal teeth were used. After preparing and disinfecting the teeth with 3% sodium hypochlorite, their crowns were cut off from the cement-enamel junction. The teeth were then randomly divided into four groups: Group 1 (n=20) Bio MTA, Group 2 MTA ProRoot (n=20), negative and positive control groups, each of them contained 3 teeth. The preparation of teeth was performed using the step back method. The filled teeth were then evaluated by fluid filtration for leakage prevention. Data were analyzed by Mann-Whitney test and Tukey test (α=0.05).
Results: The results of statistical analysis showed that there was no significant difference between the MTA ProRoot and Bio MTA in sealing ability (P>0.05). That micro leakage is less in the Bio MTA group than in the ProRoot MTA group, but the difference was not significant.
Conclusion: This study showed that MTA ProRoot and Bio MTA can be used as appropriate canal filling materials.
Sasan Rasaeipour, Mahroo Vojdani, Safoura Ghodsi,
Volume 31, Issue 3 (11-2018)
Abstract
Background and Aims: Cleft lip and palate is among challenging dentistry problems that calls for a multidisciplinary treatment approach. The treatment protocols in adults aims to improve function, appearance, and psychological conditions. The present article aimed in introducing the procedure of conventional prosthesis application for treatment of an adult patient focusing on complicated intra-operatory challenges.
Materials and Methods: A 52-year-old male patient was referred for correcting his functional deficiency resulted from bilateral cleft lip and palate. After surgical stent fabrication and vestibuloplasty, transitional prosthesis was fabricated using “Melted-sugar method”. Six month later, Richmond copings and fixed prostheses were made and the treatment was completed by delivery of mandibular removable partial prosthesis and maxillary obturator. Finding the correct position of hard palate, not interfering with normal phonetic, and hollowing his obturator, along with stablishing correct vertical dimension were among several challenges call for special considerations.
Conclusion: Following sound procedure, the conventional prosthetic treatment could be considered as an acceptable and applicable treatment option for adults suffering from untreated cleft palate, who are not good candidates for more complicated treatment procedures.
Farzane Jabari, Behzad Houshmand, Saeed Hesaraki,
Volume 31, Issue 3 (11-2018)
Abstract
The Guided Bone Regeneration (GBR) treatment concept advocates that regeneration of osseous defects is predictably attainable via the application of occlusive membranes, which mechanically exclude non-osteogenic cell populations from the surrounding soft tissues, thereby allowing osteogenic cell populations originating from the parent bone to inhabit the osseous wound. The use of membrane to exclude non-osteogenic cells, is a key principle of guided bone regeneration. A large number of membranes have been evaluated in clinical and experimental studies. The object of this study was to review the literature regarding guided bone regeneration and all types of membranes that were used in this technique. 72 articles between the years 1968 through the 2016 from PubMed, Medline and Google Scholar using the related keywords, were selected. Finally, we concluded that the modification of mechanical and physico-chemical properties of membranes could improve the process of new bone growth. However, determination of the exact role of membrane porosity in this process, still needs to be clarified. Optimization the chemical composition of membrane with the focus and attention to obstructive property and bioactivity, is an important point in this research field. Various factors such as flexibility, mechanical strength and degradation rate determine the type of membrane used for bone tissue regeneration.
Fatemeh Ensafi, Tabassom Hooshmand, Maryam Pirmoradian,
Volume 32, Issue 1 (7-2019)
Abstract
Background and Aims: Today, resin composites are one of the most commonly used materials in restorative dentistry. However, failure in resin treatments is also common due to its chemical nature and its high talent for decay recurrence. According to conservative approaches, "conservative" treatments are more likely to be considered than "Replacement" of damaged remedies. The purpose of this study was to compare different surface preparation methods on composite surfaces to achieve the highest bond strength between the old and new composites after accelerated aging.
Materials and Methods: First, composite cylinders with a diameter of 6 and a height of 5 mm were prepared using an incremental technique and a microhybrid resin composite. The specimens were stored in distilled water for 6 months at 37°C and then the surfaces of all aged compsites were roughened using diamond milling followed by phosphoric acid etching. The specimens were randomly subjected into five groups. Group 1: GC Composite Primer. Group 2: Universal bonding containing silane (Kuraray). Group 3: Self etching adhesive (SE bond; Kuraray) Group 4: silane (Ivoclar Vivadent) + Second bottle of SE bond bonding system (Kuraray). Group 5: control group with no treatment. Then, 5 mm incremental of new composite (similar to the aged composite with different color) were placed on the surfaces of specimens, sectioned, and thermocycled for 3000 cycles for the microtensile bond strength evaluation. The specimens were evaluated using a stereomicroscope after failure. Data were analyzed by one-way ANOVA and Post Hoc Tukey test.
Results: The specimens in which silane and SE bond were used showed the highest mean microtensile bond strength and those treated by universal bond showed the least bond strength which were significantly different (P=0.02). All samples had cohesive failure patterns in all groups and the percentage of failures in old and new composites did not differ significantly (P=0.69).
Conclusion: : Based on the results, all surface preparations used in this study could provide an appropriate bond strength for repair of old composite restorations. Also, the microtensile bond strength between the old and new composites was higher than the cohesive strength of resin composite itself. However, the mean microtensile bond strength value for the group treated by universal bond was significantly lower than those treated by silane and hydrophobic containing bonding system.
Mohammad Najafi, Hassan Semyari, Rokhsareh Sadeghi, Fatemeh Mashhadiabbas, Fereshteh Shanei,
Volume 32, Issue 3 (11-2019)
Abstract
Background and Aims: Reconstruction of osseous defects is one of the ideal goals of periodontal treatments and dental implant therapy. Different biomaterials have been used for this purpose and many studies have tried to compare and introduce the best ones. The present study aimed to evaluate the effect of PDFDB (Partially Demineralized Freeze-Dried Bone Graft) and FDBA (Freeze Dried Bone Allograft) on the regeneration of rabbit calvarial defects.
Materials and Methods: In this experimental study, 48 similar defects with the diameter of 8 mm were generated in the calvarium of 16 rabbits. Two defects were filled with FDBA and PDFDB, while the other one remained unfilled as the control group. All defects were covered by collagen membranes. 6 and 12 weeks after surgery, the histologic and histomorphometric tests were performed to evaluate the following variables: the rate of new bone formation and its type, the amount of residual grafting material, degree of inflammation and pattern of bone formation. Comparison of osteogenesis percentage and residual biomaterial was performed by repetitive variance analysis, whereas qualitative variables were compared by Friedman non-parametric test.
Results: Regarding bone formation percentage, there was no statistically significant difference between three different groups at 6-week (P=0.33) and also at 12-week time points (P=0.98). The amount of residual material in the PDFDB group was significantly lower than FDBA (P=0.04) in the 6-week samples. However, this difference was not significant in the 12-week samples (P=0.41). Bone quality showed statistically significant difference between graft containing groups and control group after 12 weeks (P=0.01). It means, all samples in FDBA and PDFDB groups displayed lamellar bone after 12 weeks while in control group, only woven bone or a combination of woven and lamellar bone was seen.
Conclusion: FDBA and PDFDB demonstrated similar regenerating effect in the rabbit calvarial bone defects and hastened bone maturation compared to the non-grafted defects.
Pooya Jannati, Mohammad Ebrahimi Saravi, Tahmineh Bamdadian, Farhad Sobouti, Sahar Cheperli, Jamshid Yazdani Charati, Nasrin Khaki, Sahba Amini, Abbas Mesgarani,
Volume 32, Issue 4 (1-2020)
Abstract
Background and Aims: One of the most important challenges for dentists is providing a crown with appropriate marginal fit and gap. The 135-degree tooth preparation found to have some advantages such as technical ease and appropriate finish line record. Despite the advantages of 135-degree tooth preparation, scant research has been done in this area. Therefore, the aim of this study was to compare 135-degree and deep chamfer tooth preparation on the marginal fit and marginal gap of posterior metal-ceramic crowns.
Materials and Methods: Deep chamfer and 135-degree tooth preparation were performed on the two first mandibular molars with healthy coronal tissue and similar size. Impression was taken from each tooth and 30 crowns were made on each die. The sample plastered with fit checkers were pressed under the force of 40 N for 3 min in a universal testing machine. They were measured and recorded under a loop with 40x power in three points on each aspect. Data were analyzed by Wilcoxon and Kolmogorov-Smirnov tests using SPSS version 24.
Results: The mean marginal fit values in deep chamfer and 135-degree were 48.5417µm and 55.3333 µm, respectively with no statistically significant difference (P>0.05). While the mean marginal gap in deep chamfer (2.4833 µm) was significantly higher (P<0.05) than 135-degree (1.0083).
Conclusion: It can be concluded that the marginal gap by 135-degree’s tooth preparation was lower than that of deep chamfer in metal-ceramic crowns. However, no significant difference in the marginal fit between the deep chamfer and 135-degree tooth preparation was found.
