scholarly journals Techniques for preparing of guide planes: in vitro comparative study

2014 ◽  
Vol 17 (2) ◽  
pp. 20 ◽  
Author(s):  
Eduardo Shigueyuki Uemura ◽  
João Maurício Silva ◽  
Alexandre Luiz Souto Borges ◽  
Eron Toshio Colauto Yamamoto

<p>The correct parallelism of guiding planes when constructing a Removable Partial Denture not only defines the axis of insertion and removal of the prosthesis, but also limits the possible axes of movement during functioning. Therefore, the purpose of the study was to compare some techniques and the use of an intra-oral device for those preparations. Dummies were performed in a direct manner, simulating the absence of teeth 15, 45, 12 and 42. The four preparation techniques chosen were: Group 1 – freehand preparation; group 2 - guide pins; Group 3 - crown guides and Group 4 - parallel intraoral device – ParalAB. No statistical difference was shown between the mean values of angles found for the freehand (82.85°) and guide pin (83.60°) groups. Also, no statistical significant difference was observed between the mean values of angles found for the resin cap (of 88.83) and intraoral device (88.58 º) groups; however they were superior to the findings for the freehand and guide pin groups. The studied methods are effective for what they were proposed; however, one should select the method according to the experience and skills, to promote the best results.</p>

2021 ◽  
Vol 14 (4) ◽  
pp. 1508-1513
Author(s):  
Ibraheem F Alshiddi

In order to assess the influence of finishing and polishing on the surface brightness and color stability of the ceramic veneer, fifty specimens were fabricated with 10 mm diameter and 2 mm thickness using IPS E-Max Ceramic. After glazing, 10 specimens were untouched as control group, and the other 40 specimens were abraded using 125µm diamond bur to create surface roughness. Forty specimens were divided into four groups (n=10), in group 1: specimens were finished using diamond point, in group 2 specimens’ surface was polished with a polishing kit, Group 3: Each specimen surface was polished with the polishing kit as in protocol 2 and was polished a polishing past and group 4 Each specimen was glazed by heating at 621℃ for 3 minutes followed by a temperature increase of 83℃/min up to 918℃ for 30 seconds. Color measurement was performed using spectrophotometer. Color stability data were analyzed using two-way ANOVA and Tukey’s HSD test (α=0.05). For Ra values, paired-samples t-tests were used to analyze the data and compare groups. The change in L and E showed a significant difference among the study groups; (group 1, group 2, group 3 and group 4) with respect to three variables L, a and b. A significant difference was noted when compared each group with the control; however, only group 2 showed a significant difference from group 4; the remaining groups demonstrated similar findings for all three variables. The study displayed a significant impact of the finishing and polishing technique on the surface brightness and color stability of ceramic restoration. However, it was evident that combination of two or three polishing techniques which includes polish kit and glaze enhances the surface finish and adds color stability by alternating the yellow – blue axis (increase in b) and red- green axis (decrease in a).


2011 ◽  
Vol 69 (2b) ◽  
pp. 365-370 ◽  
Author(s):  
J Bustamante ◽  
M Socolovsky ◽  
R S Martins ◽  
J Emmerich ◽  
M G Pennini ◽  
...  

Epineural stitches are a means to avoid tension in a nerve suture. We evaluate this technique, relative to interposed grafts and simple neurorraphy, in a rat model. METHOD: Twenty rats were allocated to four groups. For Group 1, sectioning of the sciatic nerve was performed, a segment 4 mm long discarded, and epineural suture with distal anchoring stitches were placed resulting in slight tension neurorraphy. For Group 2, a simple neurorraphy was performed. For Group 3, a 4 mm long graft was employed and Group 4 served as control. Ninety days after, reoperation, latency of motor action potentials recording and axonal counts were performed. Inter-group comparison was done by means of ANOVA and the non-parametric Kruskal-Wallis test. RESULTS: The mean motor latency for the simple suture (2.27±0.77 ms) was lower than for the other two surgical groups, but lower than among controls (1.69±0.56 ms). Similar values were founding in both group 1 (2.66±0.71 ms) and group 3 (2.64±0.6 ms). When fibers diameters were compared a significant difference was identified between groups 2 and 3 (p=0.048). CONCLUSION: Good results can be obtained when suturing a nerve employ with epineural anchoring stitches. However, more studies are needed before extrapolating results to human nerve sutures.


Author(s):  
Shahram Mosharrafian ◽  
Maryam Shafizadeh ◽  
Zeinab Sharifi

Objectives: This study aimed to compare the fracture resistance of a bulk-fill and a conventional composite and a combination of both for coronal restoration of severely damaged primary anterior teeth. Materials and Methods: In this in vitro experimental study, 45 primary anterior teeth were randomly divided into three groups. After root canal preparation, the canals were filled with Metapex paste such that after the application of 1 mm of light-cure liner, 3 mm of the coronal third of the canal remained empty for composite post fabrication. Filtek Z250 conventional composite was used in group 1, Sonic-Fill bulk-fill composite was used in group 2 and Sonic-Fill with one layer of Filtek Z250 as the veneering were used in group 3. Adper Single Bond 2 was used in all groups. The teeth were thermocycled, and fracture resistance was measured by a universal testing machine. The mode of fracture was categorized as repairable or irreparable. Data were analyzed using one-way ANOVA. Results: The mean fracture resistance was 307.00±74.72, 323.31±84.28 and 333.30±63.96 N in groups 1 to 3, respectively (P=0.55). The mean fracture strength was 14.53±2.98, 15.08±2.82 and 15.26±3.02 MPa in groups 1 to 3, respectively (P=0.77). The frequency of repairable mode of failure was 80% for the conventional, 73.6% for the bulk-fill and 80% for the bulk-fill plus conventional group, with no significant difference (P>0.05). Conclusions: Bulk-fill composites can be used for coronal reconstruction of severely damaged primary anterior teeth similar to conventional composites to decrease the treatment time in pediatric patients.


2012 ◽  
Vol 27 (12) ◽  
pp. 905-911 ◽  
Author(s):  
Jairo Zacchê de Sá ◽  
José Lamartine de Andrade Aguiar ◽  
Adriana Ferreira Cruz ◽  
Alexandre Ricardo Pereira Schuler ◽  
José Ricardo Alves de Lima ◽  
...  

PURPOSE: To evaluate the effect of local nitroglycerin on the viable area of a prefabricated flap for vascular implant in rats, and to investigate the surgical delay procedure. METHODS: A femoral pedicle was implanted under the skin of the abdominal wall in forty Wistar rats. The animals were divided into four groups of ten: group 1 - without surgical delay procedure and local nitroglycerin; group 2 - with surgical delay procedure, but without local nitroglycerin; group 3 - without surgical delay procedure, but with local nitroglycerin; and group 4 - with simultaneous surgical delay procedure and local nitroglycerin. The percentages of the viable areas, in relation to the total flap, were calculated using AutoCAD R 14. RESULTS: The mean percentage value of the viable area was 8.9% in the group 1. 49.4% in the group 2; 8.4% in the group 3 and 1.1% in the group 4. There was significant difference between groups 1 and 2 (p=0.005), 1 and 4 (p=0.024), 2 and 3 (p=0.003), 2 and 4 (p=0.001). These results support the hypothesis that the closure of the arterial venous channels is responsible for the phenomenon of surgical delay procedure. CONCLUSION: Local nitroglycerin did not cause an increase in the prefabricated viable flap area by vascular implantation and decreased the viable flap area that underwent delay procedures.


2019 ◽  
Vol 13 (04) ◽  
pp. 569-573 ◽  
Author(s):  
Abidin Talha Mutluay ◽  
Merve Mutluay

Abstract Objectives The purpose of this in vitro study was to investigate the effects of different disinfection methods on microleakage of Class V Giomer restorations. Materials and Methods Class V cavity preparation was performed on 40 sound permanent central incisors. Class V cavities (3 x 2 x 2 mm) were prepared on the buccal surfaces of the selected teeth. The teeth were randomly divided into four groups, each to be disinfected with a different method: Group 1—Disinfection with 2% chlorhexidine, Group 2—Disinfection with 6% sodium hypochlorite, Group 3—Disinfection with erbium, chromium: yttrium-scandium-gallium-garnet laser, Group 4—Control (distilled water). BeautiBond adhesive and Beautifil II Giomer restoration materials were applied to all surfaces of the cavities after the disinfection of all groups. The teeth were thermocycled 5,000 times (5–55°C), and then were immersed in 0.5% methylene blue for 24 hours. After rinsing, the teeth were longitudinally sectioned and dye penetration was assessed under a stereomicroscope (40x) to evaluate microleakage. Statistical Analysis The results were statistically evaluated by using the Kruskal–Wallis and Mann–Whitney U tests. Results Statistically, no significant difference was found between all four groups (p > 0.05). There was no statistically significant difference in microleakage scores of study groups (p > 0.05). Also, the microleakage scores of the gingival margins were significantly higher than the incisal margins (p < 0.0001). Conclusions Application of the different cavity disinfectants has no effect on the microleakage of Class V Giomer restorations.


Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 1500-1500
Author(s):  
Victoria J Weston ◽  
Tracey A Perry ◽  
Katie Brown ◽  
Shaun R Wilson ◽  
Pamela R Kearns

Abstract Abstract 1500 Five year survival rates for childhood AML in children are currently 55–65%. AML is an extremely heterogeneous disease, and while prognostic significance of some karyotypic abnormalities has become evident, the biology of the disease remains largely unknown. Full characterisation of leukaemia initiating cells which may be responsible for relapse has not yet been undertaken. We investigated the leukaemic stem cell populations from 10 childhood primary AML samples by comparing expression of CD34, CD38 and CD45RA, a marker of a committed granulocyte-macrophage progenitor (GMP)-like population frequent in adult AML, in vitro daunorubicin sensitivity and engraftment in immuno-compromised NOD/Shi-scid/IL-2Rgnull (NOG) mice. Consequently, we were able to classify AML samples into 4 subgroups. These comprised Group 1, CD34+CD38- AML (n=1); Group 2, CD34-CD38+CD45RA- (<10% CD34+ blasts) AML (n=4); Group 3, CD34+CD38+CD45RA- (>10% CD34+ blasts) AML (n=4); and Group 4, CD34-CD38+CD45RA+ (<10% CD34+ and >10% CD45RA+ blasts) (n=1). There was no apparent enrichment for high risk prognostic karyotypes in any of the groups. The Group 1 AML presented at 3y with t(16;21); In Group 2 AMLs, the mean presentation age was 11y, 2 carried good prognostic t(8;21), while 1 had MLL involvement and 1 had FLT3-ITD with chromosome 13 isodisomy, both higher risk indicators; The Group 3 AMLs presented with a mean age of 11.9y and 2 carried good prognostic inv(16) whereas 2 had FLT3-ITD one with additional chromosome 13 isodisomy, t(5;11) and TP53 loss. Finally, the Group 4 AML presented at 1.5y with a normal karyotype. When we compared the 2 most frequent subgroups, Group 2 had a much shorter mean EFS of 122d (n=2) compared with a 275d (n=4) for Group 3 (the mean follow up was 282d and 1013.5d, respectively). We next sorted four cell subpopulations based on CD34 and CD38 expression (CD34+CD38-, CD34+CD38+, CD34-CD38- and CD34-CD38+ blasts) and compared in vitro sensitivity to daunorubicin. In Group 1, CD34- and CD34+ cells were equally sensitive at nanomolar IC50 doses. In 2 of the Group 2 AMLs,CD34-CD38- cells were the most resistant to daunorubicin at micromolar IC50 doses (2.5-10mM) whereas the CD34-CD38+ cells (also the dominant subpopulation in this group) were the most sensitive cells exhibiting nanomolar IC50 doses (750–800nM). In contrast, the Group 3 AMLs were overall more sensitive to daunorubicin exhibiting lower nanomolar IC50 doses. Again in this group, the CD34-CD38- cells were typically the most resistant (this time being the dominant subpopulation) whereas the CD34+CD38+ were the most sensitive cells. Finally, in the Group 4 AML, while CD45RA+ cells rapidly underwent spontaneous apoptosis, CD45RA- cells exhibited extreme resistance to daunorubicin (IC50 >10mM) and CD38 expression had no impact on sensitivity. The reduced sensitivity of Group 2 AMLs to daunorubicin compared with Group 3 could, therefore, be an underlying factor contributing to shorter EFS. Finally, we initiated comparison of the stem cell qualities of the different subpopulations from representative samples from each of the two major subgroups, first by assessment of differentiation potential in vitro, and second by engraftment in vivo using NOG mice. In on-going experiments, the time to leukaemia will be compared between mice injected with unsorted and sorted cells and, at terminal cull, cells harvested from organs will be characterised by karyotype and immunophenotype and tested for clonogenic potential via subsequent serial transplantations. Peripheral blood sampling currently suggests higher human CD45+ engraftment in mice injected with sorted versus unsorted cells, and these are CD34+CD33+CD3- recapitulating the AML phenotype. We anticipate that particular subpopulations will be enriched for AML stem cells with the ability to repopulate the leukaemia. Overall, we have shown that childhood AML is diverse with respect to stem cell characteristics. AMLs with low CD34 (Groups 2 and 4) exhibit the greatest overall resistance to daunorubicin as well as shorter EFS. Furthermore, in the majority of AMLs, CD34-CD38- blasts exhibit the least sensitivity to daunorubicin. Novel therapies which can target these resistant subpopulations with leukaemia initiating activity could significantly improve the treatment responses in this clinically challenging disease. Disclosures: No relevant conflicts of interest to declare.


2008 ◽  
Vol 9 (7) ◽  
pp. 65-72 ◽  
Author(s):  
Emre Ozel ◽  
Yonca Korkmaz ◽  
Nuray Attar

Abstract Aim The aim of this in vitro study was to investigate the cervical microleakage and internal voids of nanocomposites comparing them with a hybrid composite in Class II restorations with the margins located coronal and apical to the cementoenamel junction (CEJ). Methods and Materials Standardized MOD cavities (one cervical margin located in dentin, one in enamel) were prepared in 40 extracted human molars and divided into four groups according to the composite used to restore them (n=10/group). Group 1: Adper Single Bond2/Filtek Supreme XT; Group 2: Excite/Tetric EvoCeram; Group 3: Prime & BondNT/Ceram X; and Group 4 (control) Adper Single Bond2/Filtek Z250. Groups were further divided into subgroups A and B. The “A” subgroups represent the level of the location of the cervial margin at 1 mm coronal to the CEJ, and the “B” subgroups represent the level of the cervical margin located 1 mm apical to the CEJ. After restoration of the cavities with nanocomposites, thermocycling, and immersion in 0.5% basic fuchsin, the dye penetration and internal voids were evaluated under a stereomicroscope. Data were analyzed with the Mann-Whitney U and Kruskal-Wallis tests with the Bonferroni correction for microleakage and with the Chi-square test for internal voids (p<0.05). Results The microleakage in the A subgroups was statistically significantly lower then B subgroups (p<0.05). No statistically significant difference was observed in terms of interface, cervical, and occlusal voids for all groups (p>0.05). No significant difference was observed between each group for three voids in all groups (p>0.05). Conclusion The location of the gingival margin affects the microleakage of nanocomposites but has no significant affect on the internal voids. Clinical Significance Gingival margin located 1 mm coronal to the CEJ provided a reduction in cervical microleakage in nanocomposite restorations. Citation Ozel E, Korkmaz Y, Attar N. Influence of Location of the Gingival Margin on the Microleakage and Internal Voids of Nanocomposites. J Contemp Dent Pract 2008 November; (9)7:065-072.


2015 ◽  
Vol 03 (02) ◽  
pp. 103-111
Author(s):  
Jaidev Dhillon ◽  
Sachin Passi ◽  
Ajay Chhabra ◽  
◽  

Abstract Objective: To compare and evaluate the fracture resistance of endodontically treated molars reinforced with various bonded restorations and to study the type of fractures in various restorations. Methods: Forty extracted mandibular molars were endodontically treated. MOD (Mesio-Occluso-Distal) cavities were prepared and Mesio-Buccal cusp was reduced in all to provide cuspal coverage. All the teeth were then divided into 4 groups. The cavities in group 1(control) were filled with high copper amalgam. Group 2 was restored with direct resin composite. In group 3 after the priming and bonding procedures as in group 2, cavity surfaces were coated with flowable resin composite. Before curing a piece of polyethylene ribbon fiber was cut and coated with adhesive resin and was embedded inside the flowable composite. The resin composite was cured with visible light cure (VLC) gun. For group 4, restorations were done according to the recommendations provided by the manufacturers of SR Adoro (Ivoclar-Vivadent, Schaan, Liechtenstein) composite material. Compressive fracture strength test was performed after at least 24 hours of the fabrication of the specimens, by application of compressive loading in a Universal testing machine, applied on the occlusal aspect of each specimen with a steel bar. The mean loads necessary to fracture were recorded in Newton and the results were statistically analyzed. Results: Group 4 (indirect composite inlay) had the greater fracture resistance and group 1(Amalgam) had the poorest. Difference between group 1 and 3, group 1 and 4, group 2 and 4 were statistically significant. No statistically significant difference was found between group 1 and 2, group 2 and 3, group 3 and 4. Predominant type of fracture in group 1 and 3 was fracture of tooth below cemento enamel junction at tooth restoration interface without mesio buccal cusp involvement. In group 2 and 4, predominant fractures were of tooth below cemento enamel junction through center of restoration without mesio–buccal cusp involvement.


2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Mehrdad Nateghi ◽  
Ramin Negahdari ◽  
Sahar Molaei ◽  
Ali Barzegar ◽  
Sepideh Bohlouli

Objectives. The impression-taking technique is one of the most critical factors that not only prevents the shrinkage caused by polymerization but also enhances the accuracy of implant impressions. Also, choosing the right time of taking impressions after splinting implants is one of the important criteria that affects the impression-taking technique. Accordingly, the present study aimed to evaluate the accuracy of different splint methods for implant impressions made at different times. Methods. In this in vitro study, a two-piece metallic index was prepared, and the patient’s jaw was simulated by placing self-cured acrylic resin in the lower part of the index. Then, two holes were made in the acrylic resin at a specific distance from each other, and the analogs were placed in these holes. Splinting of impression copings was carried out with autopolymerized acrylic resin (GC Pattern resin LS, GC America Inc., USA), and an open tray impression approach was performed. Thirty-six casts in three groups (n = 12) were fabricated from the acrylic model. After scanning the casts, the impression accuracy was compared between the three study groups by measuring the distance between the outer portions of the scan bodies screw-retained on implant analogs inside the cast using the Exocad software (2015.07 version). Group 1: splinting impression copings with autopolymerized acrylic resin and impression making immediately after the setting time (4 minutes); group 2: splinting and impression procedure after 17 minutes with splint sectioning and reconnection; group 3: splinting and impression procedure after 24 hours with splint sectioning and reconnection. The data were analyzed using SPSS 17 using the Kruskal–Wallis test. Results. The mean distance measured in group 1 was 19.14 ± 0.029 mm, which was significantly lower than the main model. The distances were 19.15 ± 0.039 and 19.159 ± 0.33 mm in groups 2 and 3, respectively. These two groups were not significantly different from the main model. Moreover, the mean distance measured in the three impression techniques was similar. Conclusions. There was no significant difference in the measurements between group 2, group 3, and the main model. Therefore, dentists can make an impression after 17 minutes to reduce chair time.


2014 ◽  
Vol 08 (04) ◽  
pp. 445-449
Author(s):  
Bahman Seraj ◽  
Sara Ehsani ◽  
Shirin Taravati ◽  
Sara Ghadimi ◽  
Mostafa Fatemi ◽  
...  

ABSTRACT Objective: The aim of this study was to comparatively assess the fracture resistance of the cementum-extended and conventional composite fillings with or without intracanal composite posts in severely damaged deciduous incisors. Materials and Methods: This in vitro study was performed on 60 extracted deciduous maxillary incisors that were randomly divided into four groups: Group 1: Composite filling (CF); Group 2: Composite filling with composite posts (CF + CP); Group 3: Composite filling extended 0.5 mm to cementum (ceCF); Group 4: Composite filling extended 0.5 mm to cementum with composite posts (ceCF + CP). The fracture resistance was assessed by exerting a progressively increasing load with a cross-head speed of 0.5 mm/min in a Universal Testing Machine. Statistical Analysis: Data were analyzed by SPSS-18 using one-way analysis of variance at ⍱ < 0.05. Results: The mean fracture resistance (MFR) values of the experimental groups were 410.57 ± 139.44 N, 564.44 ± 92.63 N, 507.5 ± 76.37 N and 601.08 ± 96.04 N. A significant difference was found between the MFR of Groups 1 and 2, Groups 1 and 4 and Groups 3 and 4 (P < 0.05). Conclusion: A superior outcome was achieved by intracanal composite posts in both conventional and cementum-extended composite fillings.


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