Comparison of the Young's modulus for six reinforced dental materials.
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Analysis of Variance↗
Biomedical subjects
B L Musikant
Publications and source records attributed to B L Musikant.
Rational predictable posthole preparation.
Restoration of the endodontically treated tooth is a common occurrence in everyday dental practice. Unfortunately, clinical posthole preparation seems to be a random technique. Even for a prefabricated post supplied with matching drills, the task is often difficult or not straightforward. Some questions inevitably arise. How long should the posthole be? How wide should the canal be prepared? How can the proper width be maintained so that the prefabricated post does not strip in the canal and lose its retention? If it is decided to use a cast post, what is the best posthole preparation to maximize retention? Is there an easy way to avoid perforating the root while preparing the canal for the post? Clinically, how can the posthole be prepared quickly, easily, and predictably every time? These key questions must be addressed when preparing the posthole.
Dental Prosthesis Retention↗
Effect of power settings on temperature change at the root surface when using a Holmium YAG laser in enlarging the root canal.
The aim of this study was to determine the maximum amount of power, in watts, that a Holmium YAG laser could deliver via a 245-micron fiberoptic to the canal surface and still not raise the temperature (delta T) of the cementum by > 5 degrees C. Sixty single-rooted teeth were divided into three groups according to power selection (0.50, 0.75, and 1.00 W). The three main outcome variables were: change in apical temperature, change in coronal temperature, and maximum size of an endodontic file that could fit into the canal after lasing. The group means for apical delta T were: 1.00 W = 2.2 degrees C, 0.75 W = 2.68 degrees C, and 0.50 W = 1.58 degrees C. The group means for coronal delta T were: 1.00 W = 1.15 degrees C, 0.75 W = 0.99 degree C, and 0.50 W = 0.56 degree C. The group means for file size were: 1.00 W = 41.25, 0.75 W = 38.75, and 0.50 W = 40.75. The canal size was increased from a size 25 file up to approximately a size 40 file with all power groups. There were no significant differences between the groups for change in apical temperature (p = 0.32), coronal temperature (p = 0.17), or maximum file size (p = 0.86) when adjustments were made for tooth dimensions. In all groups studied, the delta T was < 5 degrees C. This represents a safe and predictable laser procedure.
Analysis of Variance↗
Pilot study comparing the photoelastic stress distribution for four endodontic post systems.
This pilot study compared stress distribution using photoelastic blocks for both vertical loading and oblique loading (26 degrees angle) for four groups of post systems (Flexi-Post, Flexi-Flange, ParaPost and AccessPost dowels). For each group, three test blocks of photoelastic material were prepared with simulated endodontic canals, and the specimens were then photographed. Minimal stresses were observed for all the posts after cementation in the unloaded state. Stress distribution for the Flexi-Post, Flexi-Flange and AccessPost were favourable under vertical loading at 134 N and oblique loadings of 89 N and 134 N. Stress patterns were symmetric over the entire length of these posts. Stress distribution for the ParaPost under vertical loading at 134 N generated stress patterns that were asymmetric with concentration of stresses apically compared to coronally. Stress distribution for the ParaPost during oblique loadings of 89 N and 134 N were asymmetric with stress concentrated apically as compared to coronally. Stress distribution for the Flexi-Post, Flexi-Flange and AccessPost were all favourable under loading conditions studied.
Birefringence↗
Comparison of the fractural strength for three combination cast post systems.
This study compared the fractural strength measured on a 45 degree angle for three combination cast post systems (Parapost, ExactaCast and Luminex 2000). A force applied at a 45 degree angle on the bench was used to simulate the clinical situation. Many similar studies are found in literature. The experiment was divided into three groups made up of 10 samples each. Castings were fabricated in semi-precious metal from: Parapost burnout post / Duralay patterns (group 1), ExactaCast / a new butyl methacrylate acrylic (AccuSet) patterns (group 2) and Luminex 2000 / Lumin-X light cured gel patterns (group 3). The fractural strength [tests] were performed using a MTS testing machine and failure was measure in pounds. Statistical analysis including a student's test were performed to ensure complete significance between groups. The ExactaCast system had the highest mean (283.9 pounds), while the Luminex 2000 system had the lowest (255.1 pounds). There was no statistical difference in the fractural strength for all three groups studied. It seemed that the fractural strength of tooth structure represents the highest level of failure obtained regarding this experimental test constraint.
Bicuspid↗
The surgical microscope, Not just for the specialist.
The surgical microscope, today used almost exclusively by endodontists, will eventually be used by general dentists as well. This will give them the ability to perform a myriad of tasks and achieve superior results.
Dental Calculus↗
Presentation of a new Flexi-Flange post system for clinical use.
Advantages of a new post design, Flexi-Flange are described. It incorporates a split-shank parallel threaded post with a flange that seats into an occlusal countersunk dentine space. This case report describes placement of three Flexi-Flange posts in a first bicuspid, canine and central incisor. The Flexi-Flange system was designed to offer high retention of the post in the root, superior distribution of stresses on insertion and under function, and long-term resistance to metal fatigue.
Contraindications↗
Dimensional accuracy of three different alginate impression materials.
PURPOSE: The purpose of this study was to evaluate the dimensional stability of three different alginate impression materials (Jeltrate [Caulk Dentsply, LD Caulk Division, Dentsply International, Milford, DE], Hydrogum [Zhermack, Padoua, Italy], and a new hydrophilic alginate material [Essential Dental Systems, South Hackensack, NJ] under five different storage conditions. MATERIALS AND METHODS: The study was divided into four groups with at least eight samples in each group. The five storage conditions were as follows: immediate, 10 minutes with a wet towel, 30 minutes without a wet towel, 1 hour with a wet towel, and 24 hours with a wet towel. A 4 X 5 factorial two-way analysis of variance (P<.05) was used on each dependent variable. Dunnett's test was used to compare each alginate with Jeltrate. RESULTS: The new hydrophilic alginate (group 4, 2:2) showed smaller measurements in the buccolingual and diagonal dimensions compared with Jeltrate (control). CONCLUSIONS: The immediate method (measured buccolingually and diagonally) produced more accurate casts for the alginate materials studied. All other materials studied were similar statistically. The new hydrophilic alginate in group 3 resulted in similar dimensional accuracy compared with Jeltrate and Hydrogum and incorporated 25% less water.
Alginates↗
Split-shank threaded posts and threaded posts: tensile properties and stress levels.
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Analysis of Variance↗
A 10-year literature review of a split-shanked threaded post.
A review of 10 years of literature on prefabricated threaded and passive post systems is presented along with recent literature supporting the validity of the split-shanked threaded post design, Flexi-Post. It is important to note that a split-shanked threaded post is altogether different from a solid-shanked threaded post. The research discussed in this article confirms the high retention of the Flexi-Post and dispels the notion that high retention must be accompanied by high stress.
Dental Prosthesis Design↗
Comparison of the photoelastic stress properties for two combination prefabricated cast post systems.
The reason for a post and core preparation is to provide an anchoring system for a final restoration to the tooth root. This experiment was divided into two groups with the following systems; ExactaCast and Parapost. Casts for these systems were fabricated in photoelastic plastic and cemented with zinc phosphate cement. These photoelastic blocks were placed in a special jig on a universal testing machine. The experiment compared the photoelastic stresses generated for these two systems in two different stress modes; vertically at 30 pounds and obliquely (at a 26 degree angle) at 20 and 30 pounds. Specimens were then photographed after cementation in the unloaded and loaded states. Minimal stresses were observed for the ExactaCast in the unloaded state, while symmetric, even patterns of stresses concentrated coronally were present in the loaded vertical and oblique states. Minimal stresses were observed for the Parapost in the unloaded state, while asymmetric, uneven patterns of stresses concentrated apically were present in the loaded vertical and oblique states. The presence of the multiple tiered system for the Exacta-Cast clearly directs stresses in a symmetric pattern, while the single tiered Parapost system directs stresses in asymmetrical pattern. The symmetric even stresses for the ExactaCast are more favorable than the asymmetric, uneven stresses for the Parapost.
Birefringence↗
Fluoride release from four reinforced composite resins; a one year study.
PURPOSE: Four fluoridated composite resins were described and separated into four groups. Two composite resins were high viscosity core materials Ti-Core (Group 1) and Ti-Core Natural (Group 2) and two were low viscosity core materials Flexi-Flow Cement with titanium (Group 3) and Flexi-Flow Natural (Group 4). MATERIALS AND METHODS: This study recorded the fluoride release measured in parts per million in deionized water for each of four fluoridated composite resins for one year. RESULTS: Repeated measures analysis of variance (RMANOVA) was computed to separately analyze interval release and cumulative release over time and between groups. One-way analysis of variance (ANOVA) (P<0.0001) was selected to compare average weekly release between the four groups. The student-Newman-Keuls (SNK) test revealed that the mean weekly release was similar for both Flexi-Flow Natural and Flexi-Flow with titanium. CONCLUSIONS: The Ti-Core systems of groups 1 and 2 were both different from the Flexi-Flow systems and different from each other. Ti-Core with titanium Group 1 yielded the greatest fluoride release over a 52-week period, followed closely by Ti-Core Natural of Group 2. The fluoride released for these systems in Groups 1-4 was similar to the ranges reported in other fluoridated dental cements and composite resins.
Analysis of Variance↗
Comparison of the photoelastic stress for a split-shank threaded post versus a threaded post.
PURPOSE: This study compared the stress distribution during insertion and after cementation for two prefabricated endodontic posts, (1) a split-shank threaded post, and (2) a threaded post with no split in the shank. MATERIALS AND METHODS: Three test blocks of photoelastic material were prepared with simulated endodontic canals for each group studied. Specimens were then photographed after insertion and cementation. RESULTS: Minimal stresses were observed for the post with a split (group 1) throughout the length of the shaft, whereas asymmetric patterns of stresses for the post without a split (group 2) were present. Stress distribution for the post without a split were concentrated more apically rather than coronally. CONCLUSIONS: The presence of a split reduces insertion and cementation stresses for this post system. The split also acts as a vent during the cementation of the post into the canal and minimizes stress concentration during cementation.
Birefringence↗
The Flexi-Flange post system and its clinical use.
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Dental Prosthesis Design↗
Open labeled, single arm trial of denture shield for the treatment of dentures.
A new denture product, Denture Shield is described. This product was designed to aid denture wearers. It results in sealing the external surfaces of denture which provides comfort, cleansability and reduces odour while the denture is under function in the mouth. A trial was conducted in which 133 persons were recruited for a four week study. Each participant was well-informed about the product benefits. A total of 71 participants completed the study. The majority of the responses were positive (62 positive responds, representing 87.3% positive). Positive responses included: improved cleansability, food not sticking to the denture, reduced odour, better fitting dentures and more denture comfort. This product is intended as an additional treatment to current denture regimen and seems to provide improved characteristics for denture wearers.
Adult↗
Post removal using a thick-walled hollow tube post design.
PURPOSE: The retention of a post into the root is critical for the successful restoration of an endodontically treated tooth. A total of 80 Access Posts (Nos. 0, 1, 2, and 3) comprising eight groups were cemented in root canals with two different luting agents, Flexi-Flow cem with titanium and zinc phosphate cement. MATERIALS AND METHODS: Removal of these Access Posts was then performed with the corresponding retreatment drills. RESULTS: None of the samples for the No. 0 Access Posts were removed by extraction with the retreatment drills. None of the samples for the No. 1 Access Posts cemented with zinc phosphate were removed by extraction with the retreatment drills. All these posts were removed by hand with a hemostat, after breakage of the cement seal. 60% (group 3) and 40% (group 7) of the samples for the No. 2 Access Posts were removed by extraction with the corresponding retreatment drills. 80% (group 4) and 70% (group 8) of samples for the No. 3 Access Posts were removed by extraction with the corresponding retreatment drills. On an average removal of each Access Post Nos. 0 and 1 took between 1 and 2 minutes. On an average removal of each Access Post (Nos. 2 and 3) took between 2 and 3 minutes. CONCLUSION: No root fractures were observed for any sample with either technique. This was confirmed by visual and radiographic analysis.
Composite Resins↗
Comparison of the retentive properties of two hollow-tube post systems to those of a solid post design.
The retention of a post in a root is critical for the successful restoration of an endodontically treated tooth. This study compared the retention of two hollow-tube post designs (Access post and World post) cemented with zinc phosphate cement or a titanium-reinforced composite resin cement (Flexi-Flow cement with titanium) with that of the control Para-Post system, a solid post design cemented with zinc phosphate cement. The experiment was divided into 11 groups of 10 samples. Retentive values were measured with a universal testing machine and the data were recorded in pounds. A one-way analysis of variance was computed and included Duncan's multiple comparisons test, Tukey's Student range test, and Dunnett's test. Duncan's multiple comparison test and Tukey's test were inconclusive. Only Dunnett's test revealed a significant difference between group 5, Access post, grooved dentin with Flexi-Flow cement with titanium (mean of 89.7 lb), and the control, group 11, Para-Post dowel cemented with zinc phosphate cement (mean of 61.3 lb). All other groups exhibited similar results with retentive values that ranged from 62 to 76 lb.
Acid Etching, Dental↗
Retentive properties of a threaded split post with attachment sleeves cemented with various luting agents.
This study determined the retention, in pounds, of Nos. 1 through 3 stainless steel attachment sleeves for the threaded split post system cemented with various cements. Post heads and matching sleeves were also sandblasted and compared with attachments not sandblasted. Four luting agents were selected, zinc oxyphosphate cement (ZOP), and three brands of composite resin cement (CRC). The experiment was divided into two parts; in part 1, samples were not treated, and in part 2, samples were sandblasted. Retentive values were recorded with a universal testing machine. A 2 x 3 x 4 factorial three-way analysis of variance was used to compute the effects sandblasting, sleeve and post type, and the luting agent. No statistical differences were recorded for sleeves not sandblasted, Nos. 1 and 2, regardless of the luting agent. The nonsandblasted No. 3 sleeve cemented with Panavia CRC had significantly greater retention than All-Bond CRC or ZOP. There were no statistical differences in retention of sandblasted sleeves for the No. 1 sleeve despite the type of luting agent. For sandblasted sleeves Nos. 2 and 3, ZOP and Panavia CRC recorded significantly greater retention than All-Bond CRC. However, there was no difference between sandblasting and not sandblasting for the No. 1 sleeve. Mean loads for Nos. 2 and 3 sleeves were substantially greater for sandblasted compared with attachments not sandblasted.
Adhesives↗