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Human Molar Teeth (human + molar_tooth)
Selected AbstractsFracture resistance of root filled molar teeth restored with glass fibre bundlesINTERNATIONAL ENDODONTIC JOURNAL, Issue 5 2010F. B. Rodrigues Rodrigues FB, Paranhos MPG, Spohr AM, Oshima HMS, Carlini B, Burnett LH Jr. Fracture resistance of root filled molar teeth restored with glass fibre bundles. International Endodontic Journal, 43, 356,362, 2010. Abstract Aim, To evaluate the effect of unidirectional or woven glass fibre tapes inserted into MOD cavity preparations on the fracture resistance of root filled molar teeth. Methodology, Extracted human molar teeth were randomly divided into six groups (n = 15) : G1 , sound teeth, control; G2 , MOD cavity preparation; G3 , MOD + root canal treatment (Endo); G4 , MOD + Endo + composite resin restoration (Resin); G5 , MOD + Endo + unidirectional fibre (UF) + Resin; G6 , MOD + ;Endo + woven fibre (WF) + Resin. The teeth were subjected to a compressive fracture test in a universal testing machine. After testing, two failure modes were classified: pulp chamber floor or cusp. Results, The highest and the lowest mean fracture strengths were found in sound teeth (G1) (4960N) and MOD + root canal treatment (G3) (612.84N), respectively, with significant differences from the other groups (P < 0.05). The remaining groups had statistically similar means. In G5 and G6, there was a tendency for fracture to occur in the pulp chamber floor compromising tooth integrity. Conclusions, The insertion of glass fibres into MOD cavity preparations and restoring them with composite resin was not different than molar teeth filled with composite resin only in terms of fracture resistance. Fibres placed into MOD cavities do not reinforce teeth. [source] Effect of placement of calcium sulphate when used for the repair of furcation perforations on the seal produced by a resin-based materialINTERNATIONAL ENDODONTIC JOURNAL, Issue 2 2007L. Zou Abstract Aim, To evaluate the sealing ability of calcium sulphate when used under composite resin for the repair of furcation perforations having different diameters. Methodology, Perforations of different diameter were created in the floors of pulp chambers in 60 extracted human molar teeth with either a number 3 (1 mm diameter) or 5 (1.5 mm diameter) round bur. The specimens of each group were divided into four sub-groups which were repaired with composite resin either alone or in combination with calcium sulphate that created an artificial floor (15 teeth group -1). Eight teeth without furcation perforations served as negative controls. In the leakage detection device, 1 mol L,1 glucose solution was forced under a pressure of 1.5 KPa from the crown towards the pulp chamber floor. The concentration of leaked glucose was measured at 1, 2, 4, 7, 10, 15 and 20 days using a glucose oxidase method and the data evaluated using the rank sum test. Results, The specimens with larger perforations repaired with composite resin alone had significantly more leakage (P < 0.05). Using calcium sulphate as an artificial floor significantly decreased leakage of smaller perforations (P < 0.05). In groups repaired with calcium sulphate under composite resin, leakage in smaller perforations was markedly lower than that in larger ones (P < 0.05). No significant difference was found between the specimens with 1 or 1.5 mm perforations repaired with resin alone (P > 0.05). Conclusions, Calcium sulphate significantly improved the sealing ability of 1 mm perforations repaired with composite resin but not for 1.5 mm perforations. [source] An in vitro comparison of adhesive systems to seal pulp chamber wallsINTERNATIONAL ENDODONTIC JOURNAL, Issue 5 2004B. Ozturk Abstract Aim, To compare in vitro the sealing properties of five different dentine adhesive materials (Prime&Bond NT (PBNT); Prompt L-Pop (PLP); Clearfil SE Bond (CSEB); Scotchbond Multi Purpose Plus (SMPP); EBS-Multi (EBSM)) inside the pulp chamber. Methodology, Seventy-five recently extracted human molar teeth were used. The roof of the pulp chambers and roots were removed under water cooling. Pulp tissue was removed, and the canal orifices were sealed. The pulp chambers were then treated with 5% sodium hypochlorite (NaOCl) for 1 min. The teeth were randomly divided into five groups of 15 teeth each. Adhesive systems were applied to the pulp chamber walls according to the manufacturers' instructions. The samples were connected to Plexiglass plates, and a fluid filtration method was used for quantitative evaluation of leakage. Measurements of fluid movement were made at 2-min intervals for 8 min. The quality of seal of each specimen was measured immediately, after 24 h, 1 week and 1 month. The data were statistically analysed by repeated-measurements multivariate anova, Friedman test, Wilcoxon signed rank test, Kruskal,Wallis of one-way anova and Mann,Whitney U -tests. The pulp chamber wall with and without NaOCl and resin,dentine interfaces of specimens were observed under a scanning electron microscope (SEM). Results, The leakage values of the materials were significantly different at different measurement periods. In all groups, leakage values decreased with time (P < 0.05). PBNT and PLP had the least leakage during immediate measurements (P < 0.05). After 1 month, leakage of all adhesive systems was not significantly different (P < 0.05). SEM observation of pulp chamber walls demonstrated that the irregular dentine surface without smear layer was present in the nontreated group. However, NaOCl application removed the collagen fibrils leaving the dentine surface smooth. At resin,dentine interfaces of specimens, no hybridization zone was observed. Conclusions, None of the materials had created a perfect seal to the pulp chamber walls. PBNT and PLP had better sealing over the short term, but over the long term, there were no differences between the materials. [source] Evaluation of the effect of four self-etching adhesives ondentin permeabilityJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2009Hasan Orucoglu Abstract Objective: The aim of this study was to evaluate the effect of two two-step and two single-step self-etching adhesives on dentin permeability using a computerized fluid filtration (CFF) test method. Methodology: Forty recently extracted sound human molar teeth were sectioned at the mid level of the crown to obtain dentin discs of 1 ± 0.2 mm. A total of 40 discs were obtained and randomly divided into four groups (n = 10). The permeability of the discs was measured using the CFF test method before and after application of the following self-etching adhesives: Hybrid Bond, G-Bond, AdheSE, and Protect Bond. Fluid movement measurements were made at 2-min intervals for 8 min, and a mean of the values obtained was calculated for each specimen. Results: The in vitro fluid conductance of dentin discs treated with Hybrid Bond and AdheSE were lower than the dentin discs treated with G-Bond and Protect Bond (p < 0.05). Conclusion: 1-Treating dentin discs with self-etching adhesives caused significant reduction of dentin permeability. 2-All self-etching adhesives allowed diffusion of distilled water. However, AdheSE and Hybrid Bond showed the lowest permeability. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009 [source] Effect of cavity varnish, amalgam liner or dentin bonding agents on the marginal leakage of amalgam restorationsJOURNAL OF ORAL REHABILITATION, Issue 5 2001S. Belli The purpose of this in vitro study was to compare marginal leakage of Class II amalgam restorations lined with different agents (two new generation dentin bonding systems, a cavity varnish and an amalgam liner). Forty freshly extracted human molar teeth were divided into five groups. Class II preparations were prepared in the mesial and distal surfaces of each molar. While the cavities in two groups were lined with two new generation bonding systems, the other two groups were treated with an amalgam lining material and a cavity varnish. Fifth group was used as control, without any lining. Amalgam* was hand-condensed into each preparation. Specimens were thermocycled, stained and sectioned. Microleakage was graded using a stereomicroscope. Mean microleakage scores for occlusal and cervical margins were calculated and analised. For the leakage values on occlusal margins, Kruskal,Wallis test indicated no significant difference in all groups. For the leakage values on cervical margins, Kruskal,Wallis test indicated significant difference in four groups when compared with controls (P < 0·001). On the other hand, there was no significant difference between the occlusal and cervical leakage values in each group. [source] Effect of Auxiliary Grooves on Molar Crown Preparations Lacking Resistance Form: A Laboratory StudyJOURNAL OF PROSTHODONTICS, Issue 2 2008DClinDent, GradDipClinDent, Po-Ching Lu BDSc(Hons) Abstract Purpose: To investigate the effect of auxiliary grooves on resistance to dislodgment of crowns on compromised molar preparations lacking resistance form. Materials and Methods: Thirty human molar teeth were randomly assigned to three groups of ten, and prepared to a height-to-width ratio of 0.3 with a total convergence of 50°, and 1-mm shoulder margin. Base metal alloy copings were constructed with a 45° loading platform and cemented with zinc phosphate cement under a 50 N load. Initially, resistance testing was conducted using a Universal Testing Machine (Instron) at 1 mm/min for all 30 specimens. Following crown dislodgment, Group 1 copings were recemented and retested, Group 2 had one axial groove added, and Group 3 had two axial grooves added. New copings for Groups 2 and 3 were made, cemented, and again tested for resistance. Standardized radiographs were taken prior to initial cementation and scanned into digital images. The percentage of area occupied by the pulpal chamber above the acrylic mounting (PS), and the closest distance to pulp from the preparation surface (CD) were measured. Results: Recementation or the addition of one groove did not affect the dislodgment values (p > 0.05), but addition of two grooves caused a highly significant increase in resistance (p < 0.001). Regression analysis showed an inverse relationship between initial resistance values and pulpal space area. Lower resistance values were observed when the pulpal space area was large (p= 0.004). Conclusions: Crowns can be recemented without affecting resistance to dislodgment. Two grooves should be incorporated into compromised molar crown preparations to increase resistance form. Teeth with large pulps and therefore less coronal dentine have poorer resistance form, and therefore would benefit from placement of auxiliary grooves. [source] Marginal Adaptation of Cerec 3 CAD/CAM Composite Crowns Using Two Different Finish Line Preparation DesignsJOURNAL OF PROSTHODONTICS, Issue 3 2006Jaber Hussain Akbar DDS Purpose: The purpose of this study was to compare marginal discrepancies of Cerec 3 CAD/CAM composite crowns, fabricated on human prepared teeth with two different finish line designs, chamfer and shoulder. Materials and Methods: Sixteen human molar teeth were used to prepare full crowns. Eight teeth were prepared with a 1-mm-wide chamfer finish line and the other eight with a 1.2- to 1.5-mm circumferential shoulder. Cerec 3 crowns were fabricated from optical impressions using Paradigm MZ100 composite polymer. Marginal adaptation was evaluated in two ways: (1) using modified United States Public Health Service (USPHS) criteria to evaluate eight preselected sites on each crown margin, and (2) using scanning electron microscopy (SEM) to measure marginal gaps on all four axial walls with 15 measurements on each wall (60 measurements per crown). An evaluation of the number of acceptable crowns, determined by having all measured sites per tooth with margin gap size less than 100 ,m, as a function of finish line design was also conducted. Results: In both chamfer and shoulder groups, there were only two crowns (out of eight) with clinically acceptable ratings for all eight measurement sites according to USPHS criteria. Fisher's chi-square analysis showed that there was no statistically significant difference in marginal adaptability as a function of finish line design ( p > 0.05). With SEM imaging, overall mean marginal gaps for the chamfer group were 65.9 ± 38.7 ,m (range 35.0 to 130.0 ,m), and for the shoulder group were 46.0 ± 9.2 ,m (range 26.3 to 55.6 ,m); this difference was not found to be statistically significant ( p > 0.05). While crown assessment based on mean marginal discrepancy measurements indicated that both the chamfer and shoulder groups were considered clinically acceptable (<100 ,m); crown acceptability based on all measurement sites being less than 100 ,m indicated that in the chamfer and shoulder groups there were four and three acceptable crowns out of eight, respectively. The Fisher's chi-square test indicated no statistically significant difference between the groups ( p > 0.05). An agreement rate of 81.2% was calculated between the two evaluation methods, modified USPHS criteria and SEM measurements. Conclusions: Based on mean marginal discrepancy measurements, the typical marginal assessment technique, Cerec 3 Paradigm MZ100 crown restorations appear to have acceptable marginal adaptability (mean discrepancies <100 ,m). Thus, the evidence from this investigation would suggest that the finish line preparation design had no effect on marginal adaptation for Cerec 3 composite crowns. [source] | ||||||||||