Typodont Teeth Research Articles

Inter‐ and Intrarater Reliability Using Different Software Versions of E4D Compare in Dental Education

The problems associated with intra- and interexaminer reliability when assessing preclinical performance continue to hinder dental educators' ability to provide accurate and meaningful feedback to students. Many studies have been conducted to evaluate the validity of utilizing various technologies to assist educators in achieving that goal. The purpose of this study was to compare two different versions of E4D Compare software to determine if either could be expected to deliver consistent and reliable comparative results, independent of the individual utilizing the technology. Five faculty members obtained E4D digital images of students' attempts (sample model) at ideal gold crown preparations for tooth #30 performed on typodont teeth. These images were compared to an ideal (master model) preparation utilizing two versions of E4D Compare software. The percent correlations between and within these faculty members were recorded and averaged. The intraclass correlation coefficient was used to measure both inter- and intrarater agreement among the examiners. The study found that using the older version of E4D Compare did not result in acceptable intra- or interrater agreement among the examiners. However, the newer version of E4D Compare, when combined with the Nevo scanner, resulted in a remarkable degree of agreement both between and within the examiners. These results suggest that consistent and reliable results can be expected when utilizing this technology under the protocol described in this study.

An experimental and computational study of the hydrodynamics of high-velocity water microdrops for interproximal tooth cleaning

The flow field and local hydrodynamics of high-velocity water microdrops impacting the interproximal (IP) space of typodont teeth were studied experimentally and computationally. Fourteen-day old Streptococcus mutans biofilms in the IP space were treated by a prototype AirFloss delivering 115µL of water at a maximum exit-velocity of 60ms−1 in a 33-ms burst. Using high-speed imaging, footage was generated showing the details of the burst, and demonstrating the removal mechanism of the biofilms. Footage was also generated to characterize the viscoelastic behavior of the biofilms when impacted by an air-only burst, which was compared to the water burst. Image analysis demonstrated the importance of fluid forces on the removal pattern of interdental biofilms. X-ray micro-Computed Tomography (µ-CT) was used to obtain 3D images of the typodont and the IP spaces. Computational Fluid Dynamics (CFD) simulations were performed to study the effect of changing the nozzle position and design on the hydrodynamics within the IP space. Results confirmed our previous data regarding the wall shear stress generated by high-velocity water drops which dictated the efficacy of biofilm detachment. Finally, we showed how CFD models could be used to optimize water drop or burst design towards a more effective biofilm removal performance.

An in vitro study to evaluate the accuracy of dies obtained from dual-arch impression trays using addition silicone impression material and tray combinations

Objectives: This study aims to evaluate and compare the accuracy of dies obtained from dual-arch impression trays using vinyl polysiloxane impression material and tray combinations. Materials and Methods: Typodont teeth were embedded in the maxillary and mandibular Dentoform model bases and mounted in an articulator using maximum intercuspation. Impressions were made with vinyl polysiloxane materials (Reprosil Putty, Aquasil Ultra Heavy, Aquasil Ultra LV [Dentsply International]) using one-step simultaneous dual viscosity technique in dual-arch plastic trays and metal trays as well as in full arch acrylic resin custom trays. These were compared for the dimensional accuracy with the dies prepared from typodont tooth as a control. Results obtained were statistically analyzed. Results: The results indicated that dies obtained from all the impression combinations showed increased dimension (acrylic resin custom trays 9.4 ± 0.048 mm, dual-arch plastic trays 9.5 ± 0.035 mm, and dual-arch metal trays 9.41 ± 0.017 mm) as compared to the dimension of control (9.39 ± 0.007 mm). Conclusion: All the tray impression material combinations showed variable accuracies. Full arch acrylic resin trays exhibited the greatest accuracy whereas dual-arch plastic trays showed the least accuracy. CLINICAL RELEVANCE TO INTERDISCIPLINARY DENTISTRY In fixed prosthodontics, a lower incidence of errors can be obtained using a combination of PVS impression material with metal or custom tray, thereby improving the accuracy of the subsequent restoration. Interdisciplinary dentistry necessitates good prosthodontics and as such prosthodontics is an integral part of good interdisciplinary dentistry.

Evaluation of three different tooth preparation techniques for metal ceramic crowns by comparing preparation depths: An in vitro study.

Aim:To determine the effect of three different tooth preparation techniques had on operator's ability to appropriately and consistently prepare teeth for metal ceramic crowns.Materials and Methods:Ninety maxillary left central incisor typodont teeth were allocated to three equal groups (A, B and C) of thirty and mounted in standard working model one at a time. A freehand approach was used to prepare the teeth in Group A, which acted as a control. Groups B and C were prepared with the assistance of silicon index and suitable depth gauge burs, respectively. A silicon index of unprepared teeth, into which contrasting colored silicon injected to occupy the space created by tooth preparation, was sectioned in the midline. Images of sectioned index were captured with optical microscope attached to a personal computer. A calibrated image analysis software was used to measure the depth of preparation (in millimeters) at five points (labial-cervical, mid-labial, incisal, mid-palatal and palatal cervical) on two occasions. These results were pooled and averaged to give a mean labial, incisal and palatal preparation depths in mm. The data were analyzed by one-way analysis of variance and Scheffe's post-hoc statistical test.Results:The mean depth of labial and incisal preparation for Groups A, B and C was 1.23 and 1.72 mm, 1.45 and 1.96 mm, 1.47 and 1.95 mm, respectively. The difference between the groups’ labial preparation depth was significant as well as the difference between groups’ incisal preparation depth. The mean palatal preparation was 0.46 mm for Group A, 0.54 mm for Group B and 0.59 mm for Group C.Conclusion:Teeth preparation for metal ceramic crowns without any assistance can lead to under-preparation of labial and incisal surface.Clinical Significance:Whenever possible, considerable importance should be given to the use of index or depth gauge burs for preparing teeth for receiving metal ceramic crowns.

Evaluation of marginal fit and internal adaptation of zirconia copings fabricated by two CAD - CAM systems: An in vitro study.

Statement of Problem:Three main factors which determine the success of an All-ceramic restoration are esthetic value, resistance to fracture and third being the marginal fit. Marginal fit and internal adaptation are crucial factors in increasing the longevity of the restoration. Newer and economical CAD CAM systems have been introduced claiming better marginal fit and adaptation of All ceramic crowns. CAD CAM systems involves scanning of the die or the tooth preparation and milling of the restoration, which may have variations among the systems available.Aim of the Study:Our study intended to check the marginal fit and internal adaptation of commonly used CAD CAM systems namely CERAMILL and CEREC -In Lab MC XL.Materials and Methods:Two groups of typodont teeth (n = 10) were prepared using a standardized protocol to receive All ceramic copings. 10 samples of Group A were used for fabrication of copings using CERAMILL system and 10 samples of Group B were used for fabrication of copings using CEREC -In Lab MC XL system. They were then luted with glass ionomer cement under mild finger pressure. Samples were embedded in resin and sliced longitudinally. They were then viewed under stereomicroscope and readings were measured along 15 points using ImageScope software. The P value was set at 0.05 at 95% confidence interval with 80% power. The data were checked for normality and unpaired t-test was used to evaluate the results of the two groups.Results:The overall internal adaptation was 61.5 ± 5.2 μm for CERAMILL and 56.9 ± 5.7 μm for CEREC -In Lab MC XL (P < 0.05). The marginal fit for CERAMILL was 83 μm and for CEREC -In Lab MC XL was 68 μm (P < 0.05).Conclusion:The marginal adaptation of CEREC -In Lab MC XL (68 μm) was found to be superior to CERAMILL (83 μm) (P < 0.05). Both the CEREC -In Lab MC XL and CERAMILL copings demonstrated internal adaptation and marginal fit within acceptable discrepancy range. When corroborating both the internal adaptation and marginal fit, CEREC -In Lab MC XL was found to be better than CERAMILL.

Measurement of total occlusal convergence of 3 different tooth preparations in 4 different planes by dental students

Total occlusal convergence of crown preparation is an important didactic and clinical concept in dental education. The purpose of this study was to compare the discrepancy between the total occlusal convergence of dental students' typodont crown preparations and the ideal range (4 to 10 degrees) in 3 different regions of the mouth and in 4 different planes of the teeth. The dental students of the Class of 2012 at Harvard School of Dental Medicine were asked to prepare typodont teeth for crowns on 3 different teeth, the maxillary left central incisor (ceramic), mandibular left first molar (complete metal), and mandibular left first premolar (metal ceramic), during their third year preclinical summative examination and the Comprehensive Clinical Examination in their fourth year. Eighteen students prepared 3 teeth in their third and fourth years, whereas 19 students participated only in their fourth year, for a total of 55 sets of 3 teeth. By using custom fit die bases to reproduce the position, a novel procedure of measuring each tooth was accomplished in 4 different planes: the faciolingual, mesiodistal, mesiofacial-distolingual, and mesiolingual-distofacial. The total occlusal convergence of each image was measured with a computer screen protractor. The gingival 2 mm of the axial wall was used to determine the taper of each wall. Linear mixed model analysis was used to estimate and compare the total occlusal convergences of different teeth and planes (α=.05). Bonferroni corrections were used to adjust for post hoc multiple comparisons. The mean total occlusal convergence varied by tooth and plane (2-way interaction; P<.001). For the first molar, dental students excessively tapered in all 4 planes; the model-predicted 99% CIs for the total occlusal convergence were as follows: faciolingual (12.7, 19.4), mesiodistal (14.0, 19.3), mesiofacial-distolingual (13,4, 19.4), and mesiolingual-distofacial (13.7, 19.1). For the central incisor, 99% CIs for the total occlusal convergence were (15.9, 24.4) for the faciolingual measurement, providing strong evidence of excessive tapering, and (4.1, 8.0) for the mesiodistal measurement, which was within the ideal total occlusal convergence range. The mesiofacial-distolingual and mesiolingual-distofacial planes in the central incisor and all 4 planes in the first premolar had mean total occlusal convergences that exceeded 10 degrees; however, excessive tapering could not be statistically established, because their CIs included values within the ideal range. The present study found significant evidence of excessive tapering in a study comparing the total occlusal convergence values of crown preparations with those of the ideal preparation for 3 different teeth in 4 different planes. The total occlusal convergence for the molar preparations had the highest mean values.

Accuracy of Ceramic Restorations Made Using an In-office Optical Scanning Technique: An In Vitro Study

The present in vitro study concerns determination of the pre-cementation gap width of all-ceramic crowns made using an in-office digital-impression technique and subsequent computer-aided design/computer-aided manufacturing (CAD/CAM) production. Two chairside video camera systems were used: the Lava Oral scanner and Cadent's iTero scanner. Digital scans were made of a first molar typodont tooth that was suitably prepared for an all-ceramic crown. The digital impressions were sent via the Internet to commercial dental laboratories, where the crowns were made. Also, an impression of the typodont tooth was made, poured, and scanned in order to evaluate the pre-cementation gap of crowns produced from scanning stone dies. These methods and systems were evaluated by creating replicas of the intermediate space using an addition-cured silicone, and the gap widths were determined using a measuring microscope. Hot-pressed leucite-reinforced glass-ceramic crowns were selected as a reference. The mean value for the marginal measuring points of the control was 170 μm, and the values for all the evaluated crowns ranged from 107 to 128 μm. Corresponding figures for the internal measuring points were 141-210 μm and 115-237 μm, respectively. Based on the findings in the present study, an in-office digital-impression technique can be used to fabricate CAD/CAM ceramic single crowns with a marginal and internal accuracy that is on the same level as that of a conventional hot-pressed glass-ceramic crown. In the present study, however, slight differences could be seen between the two types of ceramic crowns studied with respect to the internal fit obtained.

Residents' journal review

Residents' journal review

A study of composite restorations as a tool in forensic identification

Introduction:Comparing ante-mortem and post-mortem dental data is a principal method of identification in forensic odontology. Radiographic images of amalgam have been used in dental forensics for identification due to their unique appearance.Aim:The aim of this study was to investigate whether radio-opaque composite restorations have a potential for identification in forensic odontology.Materials and Methods:Thirty typodont mandibular first molar teeth were prepared with Class-II (proximo-occlusal) cavities and restored with a radio-opaque composite (Tetric N-Ceram). Two sets of standardized radiographs were taken from the 30 teeth, keeping the radiological parameters constant. One set of these 30 radiographs was named as SET 1. Ten randomly chosen radiographs from the other set and two other radiographs of Class-II composite restorations in typodont teeth constituted SET 2. Thirty dentally trained examiners were asked to match the 12 radiographic images of SET 2 with those of SET 1.Results:The results show that 15 examiners were able to correctly match all the 12 images. Statistical analysis was done using kappa statistical test.Conclusion:This study shows that, if the post-mortem radiographs are accurate duplicates of ante-mortem radiographs of composite restorations, then the shape of the composite restoration is unique and can be used for identification.

The failure load of CAD/CAM generated zirconia and glass-ceramic laminate veneers with different preparation designs

Fracture of feldspathic porcelain laminate veneers represents a significant mode of clinical failure. Therefore, ceramic materials that withstand a higher load to fracture, especially for patients with parafunctional habits, are needed. The purpose of this study was to examine the correlation of material (zirconia, TZP, glass-ceramic, IEC, and feldspathic porcelain, FP) design (incisal overlapped preparation, IOP, and three-quarter preparation, TQP), and fracture mode to failure load for veneers supported by composite resin abutments. A typodont tooth prepared with 2 designs (IOP, TQP) and the corresponding 2 definitive dies were used to fabricate the composite resin abutments (30 for IOP and 30 for TQP). Ten veneer specimens for each system (Y-TZP, IEC, and FP), were fabricated for each design. The veneers were cemented, invested, and tested in compression until failure by using a universal testing machine. Significant differences were evaluated by 2-factor ANOVA (α=.05). No statistical mean load difference was noted between the preparation designs for Y-TZP (IOP: 244 ±81 and TQP: 224 ±58 N), IEC (IOP: 306 ±101 and TQP: 263 ±77 N), and FP veneers (IOP: 161 ±93 and TQP: 246 ±45 N). No statistical difference in the mean load was found among the 3 veneer materials for each preparation design except between IEC (306 ±101 N) and FP (161 ±93 N) veneers for TQP. Preparation design did not influence the failure load of the veneer materials. Zirconia veneers were the least likely to fracture but the most likely to completely debond; feldspathic porcelain veneers exhibited the opposite characteristics.

Evaluation of the spatter-reduction effectiveness of two dry-field isolation techniques

BackgroundThe authors conducted a study to compare the effectiveness of two dry-field isolation techniques with that of a control technique (no isolation) in reducing spatter from a dental operative site.MethodsThe authors designed a benchtop experiment to evaluate spatter patterns after performing simulated occlusal surface preparations on three typodont teeth in a dental manikin. Fluorescein dye served as the marker to enable visualization of the spatter distribution. The authors compared the effectiveness of a nonisolated control consisting of high-volume evacuation (HVE) alone with that of two dry-field isolation techniques: a dental dam with HVE and the Isolite system (Isolite Systems, Santa Barbara, Calif).ResultsThe authors performed a two-way analysis of variance. Both the Isolite device and the dental dam with HVE exhibited a significant decrease in the number of contaminated squares (P < .001) compared with that for the nonisolated control. In addition, overall, the results showed no statistically significant difference between the Isolite system and the dental dam with HVE (P = .126).ConclusionsThe study results showed that use of a dental dam with HVE or the Isolite system significantly reduced spatter overall compared with use of HVE alone.Clinical ImplicationsIsolation with a dental dam and HVE or with the Isolite system appears to aid in the reduction of spatter during operative dental procedures, potentially reducing exposure to oral pathogens.

Comparison Between Laceback and Tie-back in Sliding Mechanics (An in vitro study)

Aims: The current study aims to investigate the rate of space closure, tipping and rotation of canine during its retraction by laceback and tieback using standard ceramic brackets along 2 types of arch- wires using typodont simulation system (Ormco). Materials and Methods: The standardization crite- ria were all typodont teeth situated in well aligned position, covered and immobilized by the acrylic bite except canine, laceback and tieback were used to slide the canine. Results: The present study showed that when slide the canine on 0.017x 0.025 inch archwire gave rise to significant decrease in the rate of space closure, degree of tipping and rotation as compared when sliding it on 0.020 inch archwire, also sliding the canine using laceback as a method of retraction gave rise to a significant de- crease in the rate of space closure, degree of tipping and rotation as compared with tieback. Conclu- sions: It was concluded that canine retraction using laceback retraction method along 0.017x0.025 inch archwire gave rise to a significant decrease in the rate of space closure, degree of tipping and rota- tion.

Evaluation of Canine Tipping During its Retraction with Sliding Mechanics.(An in Vitro Study)

Aims: The present study concerned with the evaluation of the effects of using different bracket,s types (material and design), different arch wire types (shape and size) and different methods of retraction (elastic chain and closed coil spring) on the degree of tipping of canine during its retraction along an arch wire using typodont simulation system (Ormco). Materials and methods: The standardization criteria were all typodont teeth situated in well aligned position, covered and immobilized by the acryl-ic bite except canine, elastic chain and nickel – titanium closed coil spring exerting 180 gm of force on canine measured carefully by tension gauge., the angle between bite plane extension,s bar and canine,s extension bar was (90°) measured by protractor directly on photographs that were taken for typodont using digital camera from both vertical and horizontal direction. Results: The present study showed that sliding the canine on large rectangular arch wire (0.019x0.025 inch) gave rise to a significant de-crease in the degrees of tipping when compared with 0.018 inch and 0.018x0.022 inch arch wires were used. Also, sliding the canine using ceramic brackets (0.022) inch gave rise to the significant decrease in the degree of tipping than when using stainless steel brackets. Another finding of the present study showed that when using elastic chain as a method of retraction gave rise to a a significant decrease in the degree of tipping as compared with nickel – titanium closed coil spring and lastly the attachment of the method of retraction around the bracket tie wing rather than hook gave rise to the high degree of tipping . Conclusion: It was concluded that the canine retraction with 0.019x0.025 inch wire on stan-dard ceramic bracket(0.022)inch by elastic chain retraction method could be regarded as the best com-bination variables that produced less degrees of tipping While the opposite is true for canine retraction with 0.018 inch wire on Roth stain less steel bracket by closed coil spring.

The effect of translucency of Y-TZP based all-ceramic crowns fabricated with different substructure designs

PurposeTo analyse the effect of translucency of Y-TZP based all-ceramic crowns fabricated with different substructure thicknesses and extensions. The effect of restoration shading is also investigated. Materials and methodsA maxillary right central incisal typodont tooth was prepared and a die was fabricated with Type IV stone after making impression. Horizontally and vertically reduced substructure extensions were designed at the facial cervical part with 0.3mm and 0.5mm thick Lava Y-TZP. Each substructure was fabricated with two different shades, FS1 and FS7. A1 shade veneering porcelain was applied on FS1 shade Y-TZP substructures and D3 shade veneering porcelain was applied on FS7 shade Y-TZP substructures with lost wax and press ceramic technique. Ten specimens were fabricated for a total of 8 groups. The cervical and body color of specimens were analysed with a spectrophotometer, after placing specimens on the two different colored abutment teeth using translucent try-in cement. The data were obtained in CIELAB color coordinates L*a*b*, and ΔE* through the test specimens over ND1 and ND8 shade abutments were calculated. ResultsAt the cervical area, there was a significant difference on substructure extension (P<0.001). At the body area, results were borderline on substructure thickness (P=0.05) and there was a significant difference on restoration shade (P=0.001). ConclusionsVertical reduction design of Y-TZP substructure could increase ΔE* at the cervical area. Decreasing thickness of Y-TZP substructure may increase ΔE* at the body area. Increasing the value of Y-TZP based-all ceramic crown shade could increase ΔE* at the body area. Clinical significanceThe translucency of a Y-TZP based all-ceramic crowns may influence its esthetic outcome when it is used on a discolored abutment tooth.Clinicians should be aware of the effect of substructure design on the translucency of Y-TZP based all-ceramic crowns.

A new method to measure mesiodistal angulation and faciolingual inclination of each whole tooth with volumetric cone-beam computed tomography images

The purpose of this study was to develop a methodology to measure the mesiodistal angulation and the faciolingual inclination of each whole tooth (including the root) by using 3-dimensional volumetric images generated from cone-beam computed tomography scans. A plastic typodont with 28 teeth in ideal occlusion was fixed in position in a dry human skull. Stainless steel balls were fixed to the occlusal centers of the crowns and to the apices or bifurcation or trifurcation centers of the roots. Cone-beam computed tomography images were taken and rendered in Dolphin 3D (Dolphin, Chatsworth, Calif). The University of Southern California root vector analysis program was developed and customized to digitize the crown and root centers that define the long axis of each whole tooth. Special algorithms were used to automatically calculate the mesiodistal angulation and the faciolingual inclination of each whole tooth. Angulation measurements repeated 5 times by using this new method were compared with the true values from the coordinate measuring machine measurements. Next, the root points of 8 selected typodont teeth were modified to generate known angulation and inclination values, and 5-time repeated measurements of these teeth were compared with the known values. Intraclass correlation coefficients for the repeated mesiodistal angulation and faciolingual inclination measurements were close to 1. Comparisons between our 5-time repeated angulation measurements and the coordinate measuring machine's true angulation values showed 5 teeth with statistically significant differences. However, only the maxillary right lateral incisor showed a mean difference that might exceed 2.5° for clinical significance. Comparisons between the 5-repeated measurements of 8 teeth with known mesiodistal angulation and faciolingual inclination values showed no statistically significant differences between the measured and the known values, and no measurement had a 95% confidence interval beyond 1°. We have developed the novel University of Southern California root vector analysis program to accurately measure each whole tooth mesiodistal angulation and faciolingual inclination, in a clinically significant level, directly from the cone-beam computed tomography volumetric images.

A comparison of grades awarded by peer assessment, faculty and a digital scanning device in a pre‐clinical operative skills course

The aim of this study was to compare the grades awarded by two experienced assessors with peer-assessment marks and measurements from a digital scanning device (Prepassistant; KaVo, Biberach, Germany), for full gold crown preparations completed in a pre-clinical operative skills course on typodont teeth. Seventy-eight preparations on typodont teeth were randomised and assessed by all three methods. Agreement was measured using weighted kappa statistics, and mean rank scores given by the Friedman test. The highest agreement was seen between the experienced assessors (0.38), closely followed by peer assessment and experienced assessor agreement (0.36, 0.29). Despite this, the results indicate poor levels of agreement. No agreement was seen between any of the assessment methods when compared to the digital scanning device. The findings of this study could be related to the difficulty of calculating a single grade from the output of the device, in addition to the inability of the machine to assess all the factors necessary for an acceptable preparation. From this study, it can be concluded that this device is not suitable for calculating grades when used in isolation. Further research could explore the role of the Prepassistant in providing student feedback, its potential to enhance the learning experience and the subsequent effect on performance.

Fabrication of Provisional Restoration Using Direct Technique

OPEN ACCESSDecember 6, 2011Fabrication of Provisional Restoration Using Direct Technique Mercedes Porter, DDS, Rainer Adarve, DDS, MS, MHPE Mercedes Porter, DDS University of Minnesota School of Dentistry - Division of Prosthodontics Google Scholar More articles by this author , Rainer Adarve, DDS, MS, MHPE University of Minnesota School of Dentistry - Restorative Sciences Google Scholar More articles by this author https://doi.org/10.15766/mep_2374-8265.9055 SectionsAbout ToolsDownload Citations ShareFacebookTwitterEmail AbstractAbstractDental students learning fixed prosthodontics should have the conceptual understanding and procedural skills that allow them to prepare teeth for full coverage restorations and also to fabricate provisional restorations for these teeth. Fabrication of a provisional restoration is a clinical skill that a dental student should be able to demonstrate. This resource provides a stepwise approach to learning how to fabricate provisional restorations for full gold and porcelain fused to metal crowns. Faculty can use this module as an adjunct to their teaching. The module can provide faculty members who have different teaching styles with a consistent method of making provisional restorations that achieve desirable results and meet the evaluation criteria. This module is used by dental students in a preclinical setting. It is intended to allow self-guided and self-paced instruction with or without the assistance of faculty. In order for the module to be employed, students should be proficient in the fundamentals, principles, and skills involved in preparing typodont teeth for full coverage restorations. This resource should be thoroughly reviewed before beginning the restoration fabrication procedures and should be followed step-by-step to achieve the goals of successful provisional fabrication. The purposes of each characteristic of an ideal restoration should be reviewed and learned prior to fabrication so that the evaluation criteria can be used effectively. This resource has been utilized in the University of Minnesota School of Dentistry preclinical Fixed Prosthodontic course for the past 2 years. Students are given a lecture about this procedure and then allowed to use this resource during their preclinical laboratory time to fabricate provisional restorations. This resource is supplemented by faculty feedback; however, this feedback time can be more effectively spent addressing specific questions and/or pitfalls rather than setting up and providing live demonstrations. Students appreciate having detailed, step-by-step instructions to follow even in the absence of faculty. Educational Objectives By the end of this module, learners will be able to: Describe the steps in fabricating a provisional restoration using direct technique.Manipulate materials such as Exaflex putty matrix material and Protemp provisional material.Fabricate provisional restoration using direct technique.Mix putty and fabricate matrix.Prepare and dispense Protemp provisional material.Fill putty matrix with Protemp, place onto typodont tooth, and remove putty matrix.Trim, polish, and evaluate provisional restoration. Sign up for the latest publications from MedEdPORTAL Add your email below FILES INCLUDEDReferencesRelatedDetails FILES INCLUDED Included in this publication: Instructor's Guide.pdf Fabrication of Provisional Restoration Using Direct Technique.pdf To view all publication components, extract (i.e., unzip) them from the downloaded .zip file. Download editor’s noteThis publication may contain technology or a display format that is no longer in use. Copyright & Permissions© 2011 Porter and Adarve. This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial-No Derivatives license.KeywordsFull Gold CrownPorcelain Fused to Metal RestorationProvisional Fabrication Direct TechniqueCrownsRestoration Disclosures None to report. Funding/Support None to report. Loading ...

Evaluation of space closure rate during canine retraction with nickel titanium closed coil spring and elastomeric chain.

Aims: . To investigate the rates of space closure achieved by elastomeric chain and nickel titanium coil springs with the evaluation of the effects of using different bracket types on the rate of space closure during its retraction along different sizes of orthodontic arch wires using typodont simulation system (Ormco). Materials and Methods: The standardization criteria were all typodont teeth situated in well aligned position, covered and immobilized by the acrylic bite except canine, elastic chain and nickel – titanium closed coil spring exerting 180 gm of force on canine measured carefully by tension gauge. The available space was 13.5mm (the rate of space closure). Results: The present study showed that when using elastic chain as a method of canine retraction gave rise to a a significant decrease in the rate of space closure as compared with nickel – titanium closed coil spring also sliding the canine using ceramic brackets gave rise significant reduction in the rate of space closure than when using stainless steel brackets. Another finding of the present study showed that sliding the canine on large rectangular arch wire (0.019x0.025 inch) gave rise to a significant reduction in the rate of space closure when com-pared with 0.018 inch and 0.018x0.022 inch arch wires were used. Conclusions: It was concluded that the canine retraction with 0.018 inch wire on Roth stainless steel bracket by closed coil spring gave rise a large amount of space closure rate. While the opposite is true for canine retraction with 0.019x0.025 inch wire on standard ceramic bracket by elastic chain retraction method.

The Chamfer Finish Line: Preclinical Student Performance Using Different Bur Designs

The primary purposes of this investigation were to evaluate sophomore dental student performance in the production of a chamfer finish line using two diamond bur types-a round-ended bur and a torpedo-shaped bur-and to gain student feedback about their preferences for bur type. Fifty students took part in the study, each of whom prepared the buccal surfaces of two mandibular molar typodont teeth, producing chamfer finish lines. Students prepared both teeth in the same laboratory session and were randomly assigned to two groups that were required to prepare the first of the two molars with a specific bur type. The prepared chamfer finish lines were scored and the data analyzed using the Wilcoxon signed-rank test. Student performance was significantly better when the round-ended bur was used (p=0.005). Student feedback was collected with a survey that consisted of four questions and the opportunity to provide write-in comments. In response to the question "Overall, was one bur type better?" 58 percent of the students preferred the round-ended bur for creating a chamfer finish line. The most frequent write-in comment, made by twelve of the fifty students, criticized the torpedo-shaped bur for creating finish lines that were too shallow or too long.

Comparison of the Marginal Fit of Pressable Ceramic to Metal Ceramic Restorations

The aim of this in vitro study was to compare the marginal adaptation of a pressed ceramic material, when used with and without a metal substructure, to a traditional feldspathic porcelain-fused-to-metal restoration with a porcelain butt margin. A maxillary central incisor typodont tooth was prepared with a 1.5 mm 360 degrees shoulder with rounded internal line angle, and 30 polyether impressions were made. Dies were poured in type IV dental stone, and 30 restorations were fabricated: 10 metal ceramic restorations (MCR) with porcelain butt joints, 10 pressed to metal restorations (PTM), and 10 all-ceramic restorations (PCR). All restorations were evaluated on their respective dies at 45x magnification using an Olympus SZX-12, measurements of the marginal openings were made, and ANOVA and Scheffé post hoc tests were used to evaluate the data. The mean marginal opening was 72.2 +/- 5.9 microm for MCR, 49.0 +/- 5.9 microm for PTM, and 55.8 +/- 5.9 microm for PCR. The post hoc tests showed that there was a statistical difference between the marginal adaptation of the PTM and MCR groups (p < 0.05). There was no significant difference in marginal adaptation between the PTM and the PCR groups, or the PCR and the MCR groups. The PTM group demonstrated a smaller mean marginal opening than the MCR group. The mean marginal openings of all three groups were within a clinically acceptable range.