Open Tray Impression Technique Research Articles

Comparative evaluation of open tray impression technique: investigating the precision of four splinting materials in multiple implants

BackgroundThis study aimed to determine the relative positioning accuracy of multiple implants utilizing four distinct types of splinting materials.MethodsThe purpose of this in-vitro study was to compare the precision of four splinting materials in an open tray impression technique in multiple implant situations. Based on the material used for splinting, four groups were made (n = 40)- Group A: Conventional Method, Group B: Prefabricated Pattern Resin Framework, Group C: Prefabricated Metal Framework, Group D: Light Cured Pattern Resin, these groups were compared with the master model. A heat-cured clear acrylic resin and a master model were constructed. A pilot milling machine drill was used to drill four parallel holes in the anterior and premolar regions, which were later labeled as A, B, C, and D positions from right to left. Then, sequential drilling was carried out, and four 3.75‑mm diameter and 13-mm long ADIN implant analogs with internal hex were placed in the acrylic model using a surveyor for proper orientation. The impression posts were then manually screwed to the implant analogs using an open tray, and they were secured to the implants using 10 mm flat head guide pins with a 15 N.cm torque. 10 Open tray polyether impressions were made, and casts were poured. Each splinting method’s distortion values were measured using a coordinate measuring machine capable of recordings in the X-, Y-, and Z-axes. Comparison of mean distances for X1, X2, and X3 was made using the Kruskal-Wallis test, and Pairwise comparison was done using Post Hoc Tukey’s Test.ResultsThe differences between the groups were significant when assessing the distances X1, X2, and X3 (p < 0.05). The comparison of deviations between the groups revealed a statistically significant difference (p < 0.05) for the deviation distance X3 but not for the deviation distances X1 and X2. For distance Y1, the difference between the groups was statistically significant (p0.05), but it was not significant for distances Y2 and Y3. A statistically significant difference was seen in the comparison between the groups (p < 0.05) for the deviation distances Y1, Y2, and Y3. The results were statistically significant for the distance Z1 comparisons, namely, control vs. Group A (p = 0.012), control vs. Group B (p = 0.049), control vs. Group C (p = 0.048), and control vs. Group D (p = 0.021), and for distance Z3 comparison for control vs. Group A (p = 0.033). The results were statistically insignificant for the distance Z2 comparisons (p > 0.05).ConclusionsAll splinting materials produced master casts with measurements in close proximity to the reference model. However, prefabricated pattern resin bars splinting showed the highest accuracy among the studied techniques. The most recent splinting techniques using prefabricated metal framework and light-cure pattern resin showed similar accuracy.

A modified open tray direct abutment level impression technique: A clinical tip

Reproducing the accurate intraoral relationship of an implant through impression making is first step in achieving accurate fit prosthesis. Traditionally impression techniques used in implant dentistry can be classified into closed tray and open tray impression techniques. Open tray impressions are considered to be more accurate as compared to the closed tray impressions in cases with multiple implants. It requires long impression copings which are picked up in the impression during impression procedure thereby reproducing the exact relationship of an implant. Present article describe a modified direct abutment open tray impression technique utilizing applicator tips in absence of long impression copings.

Comparison of accuracy of hexed and nonhexed pickup impression copings in a multiple variable impression setup for recording multiple straight and angulated implant positions: An in vitro study.

The aim of this study was to evaluate and compare the accuracy of hexed and nonhexed pickup impression copings with and without splinting using polyether (PE) and polyvinyl siloxane (PVS) impression materials in open-tray technique in recording multiple straight and angulated implant positions. An accurate impression results in an accurate definitive cast, thus minimizing the incidence of prosthesis misfit. The critical aspect is to record the three-dimensional location of the implant in bone rather than reproducing fine surface details. Precise fit of a fixed implant-supported prosthesis depends on the accuracy of the implant analog location within the definitive cast. Factors which affect impression accuracy include implant angulation, impression material, impression copings, technique, and splinting. A sample size of 80 study models fabricated from the impression of different groups was included. A reference master model based on All-on-4 implant concept with two parallel (implants 1 and 2) and two angulated (implant 3 at 17° and implant 4 at 30°) was fabricated using implant angulation guide. All impressions were recorded using open-tray impression technique. The groups were divided into two main groups of 40 samples each. Group A used hexed open-tray impression copings and Group B used nonhexed open-tray impression copings. Both the groups involved impression recording using splinted (Subgroup I) and nonsplinted impression copings (Subgroup II). Further, impressions in each subgroup were made using PE (Subsubgroups a) and PVS (Subsubgroup b). A total of eight subsubgroups with ten samples each were included. Impressions were recorded for each group and poured into Type IV die stone for fabrication of study models. After 24 h, the study models and reference master model were fitted with implant abutments for measurement with coordinate measuring machine. The mean differences of the interimplant distance R1 (1-2), R2 (1-3), R3 (2-4), and R4 (3-4) between the reference model and sample models in different subsubgroups were calculated and three-way analysis of variance test was applied with Tukey's post hoc tests. No significant difference was found in mean coronal deviations for distance R1, R2, and R3 (P > 0.05) between different study groups. P = 0.02 for R4 (distance between 17° and 30° implants) between impression materials subsubgroups suggested that significantly less distortion was created in location of highly angulated implants (>30°) using PVS impression material. Splinting and type of coping did not have a significant influence on impression accuracy. Increasing angulation decreased the accuracy. PVS was found equivalent in accuracy to rigid PE for recording parallel or angulated implants. Impressions of implants with higher angulations were recorded more accurately with PVS. The study found no difference in accuracy with or without splinting. Furthermore, nonhexed impression copings facilitate easier and accurate recording of multiple angulated implant location in bone.

Evaluation of accuracy and time taken to make an open tray implant impressions with two techniques.

Implant dentistry's emergence and acceptance have provided physicians with a wide range of new options for fixed and removable rehabilitation. The eventual replacement of the lost tooth is the ultimate success, and this can be accomplished using recognized prosthodontic methods. The present study aims to evaluate the time and dimensional accuracy of implant definitive models with an open tray impression with two different techniques. Impression was made in two different techniques and the cast was poured and checked for the time taken and the accuracy of the impression. In IBM SPSS software version 23.0 all the results were statistically analyzed. An Independent t-test was performed for the parameters. No statistically significant difference was present (P > 0.05) when comparing the accuracy and time taken between the two groups. It is concluded that time taken and the misfit is less for modified open tray impression techniques when compared to the regular open tray impression.

Fabrication of non-replaceable superstructures on conventional and digital impression intraosseous implants

Introduction : Implantology is the fastest growing specialty in dentistry. A key point for the accurate fabrication of fixed prosthetic structures is taking an accurate impression of the prosthetic field. The implant-prosthetic restoration of the masticatory apparatus after the composition of the function and aesthetics of the dentition through digital technology is gaining wider popularity. Aim : The purpose of this article is to address impression materials and compare the two methods of impression taking from implants—conventional and digital—and clarify their advantages and disadvantages. Materials and Methods : After reviewing materials, studies, and publications on the subject, we tried to present and systematize the main methods and techniques for taking an impression of implants in a conventional and digital way, as well as their advantages and disadvantages. The search was conducted using various keywords and combinations: “transfer impression”, “conventional impression”, “intraoral scanner”, “CAD/CAM”, “scan body”. Results : Forty-one original and review articles were reviewed. Impression materials, impression-taking techniques in permanent implant prosthodontics by conventional and digital methods, and types of intraoral scanning systems are discussed. Conclusion: Taking an accurate impression is a key point in implantology. There are differences in the impression taking techniques of implants. Two main impression techniques are used, direct with an open tray and indirect with a closed tray. According to many literature sources, the open-tray impression technique is more precise and produces more accurate results, while others believe that the closed-tray technique is more accurate. More and more often, conventional impressions are being replaced by digital ones. Digital impressions entered dentistry and, in particular, implantology as an alternative to conventional ones for the restoration of small defects such as single crowns and short bridges.

Digital assessment of the accuracy of implant impression techniques in free end saddle partially edentulous patients. A controlled clinical trial

ObjectivesThis in vivo study aims to assess the accuracy of the digital intraoral implant impression technique, the conventional closed-tray impression technique, and open-tray impression techniques in a standardized method of data segmentation along with the best-fit algorithm to overcome the inconsistency of results of previous studies regarding implant impression techniques.Materials and methodsSixteen implants were placed in eight patients. Each patient has undergone four impression techniques: direct intraoral scanning of the stock abutment, intraoral scanning using a scan body, conventional closed tray impression technique, and the conventional open tray impression technique. The conventional impressions were poured into stone casts with analogues and stock abutments and scanned using a desktop scanner. In intraoral scanning of the scan body, computer-aided design software was used for the replacement of the scan body with a custom-made abutment that is identical to the stock abutment, allowing comparison with the other impression techniques. The deviation in implant position between the groups was measured using special 3D inspection and metrology software. Statistical comparisons were carried out between the studied groups using a one-way analysis of variance (ANOVA) test.ResultsThe total deviation between groups was compared to the reference group represented by the intraoral scanning of the abutment. The total deviation was statistically significantly different (P = 0.000) among the different studied groups. The mean deviation was recorded as 21.45 ± 3.3 μm, 40.04 ± 4.1 μm, and 47.79 ± 4.6 μm for the intraoral scanning of the scan body, the conventional closed, and open tray, respectively.ConclusionFor implant impressions in partially edentulous patients, intraoral oral scanning using a scan body significantly improves scanning and overall accuracy. Regarding conventional impressions, the closed-tray impression techniques showed more accuracy than conventional open-tray impressions.Clinical relevanceIntraoral digital implant impression using scan body offers more accuracy than conventional implant impression techniques for recording posterior implant position in free-end saddle partially edentulous patients.

Comparison of the accuracy between conventional and various digital implant impressions for an implant-supported mandibular complete arch-fixed prosthesis: An in vitro study.

This in vitro study compared the accuracy between conventional and different intraoral scanner impression methods and stereophotogrammetry term of 3D deviation for a complete mandibular edentulous arch with 5 placed implants. An edentulous mandibular model was prepared with three straight and two 17° angled screw-retained abutments screwed on implants. Different impression techniques were compared: one conventional impression, CO (open-tray splint impression coping, Polyether), three groups of intraoral scanners, TS (Trios 4), IT (iTero Element 2), and PS (Primescan), and one stereophotogrammetry, PIC (Precise Implants Capture). An extraoral scanner (E4 scanner) was used to digitize the reference model as a control group. Scan body positions were compared with 3D deviation by using a 3D analysis software program (Geomagic ControlX 2020.1.1) with the best-fit alignment technique. The accuracy of the scan bodies' position of each impression technique between each group area was analyzed using one-way ANOVA followed by Scheffé's comparison test for trueness and precision. (α = 0.05). Statistical 3D deviations of the whole scan body were found among the CO, TS, PS, IT, and PIC groups for both trueness (p < 0.05) and precision (p < 0.05). PIC showed the least 3D deviation of trueness (48.74 ± 1.80µm) and precision (5.46 ± 1.10µm), followed by TS, PS, IT, and CO. CO had the highest 3D deviation of trueness (141 ± 5.58µm) and precision (40.4 ± 1.3.39µm), which was significantly different from PIC, TS, and PS. For completed-arch digital implant impressions, stereophotogrammetry has shown better accuracy than other digital and conventional impression techniques, especially in terms of precision. The highest 3D deviation was found in the conventional splint open-tray impression technique.

Accuracy of Impression Techniques for Dental Implants Placed in Five Different Orientations.

The purpose of this study was to evaluate the impression accuracy of two implants placed in different orientations and compare the impression accuracy obtained with the dual-arch impression technique using hybrid impression copings and the conventional open-tray impression technique. Five mandibular dentiform models were prepared by placing implants in the second premolar and second molar regions in the following different orientations: parallel to each other; 15-degree mesiodistal angulation; 30-degree mesiodistal angulation; 15-degree buccolingual angulation; and 30-degree buccolingual angulation. After making 10 impressions for each model with the open-tray impression technique and dual-arch impression technique with hybrid impression copings, cast models were fabricated for each impression (n = 10). Scan bodies were mounted on the five dentiform models and the fabricated 100 cast models were scanned using a desktop scanner. The three-dimensional deviation of the scan bodies on the cast models was calculated and compared to the reference data from the dentiform models. A two-way analysis of variance was conducted (α = .05). The root mean square deviation values obtained from the implants placed with 30-degree mesiodistal angulation were 93.05 ± 6.21 μm with the open-tray impression technique and 104.01 ± 8.89 μm with the dual-arch impression technique, which were the largest deviation values for both techniques (P < .001). Compared to the open-tray impression technique, the dual-arch impression technique with the hybrid impression copings showed significantly lower accuracy when the angulation between the implants was 15 degrees mesiodistally (P < .001), 30 degrees mesiodistally (P = .016), or 30 degrees buccolingually (P < .001). However, there was no significant difference between the accuracy of the two impression techniques for parallel implants (P = .74). When the two implants were inclined 30 degrees mesiodistally, both implant impression techniques showed the largest deviation and the dual-arch impression technique showed lower accuracy compared to the conventional open-tray impression technique. Parallel placement of implants may improve impression accuracy and enable use of the dual-arch impression technique.

Accuracy of photogrammetry, intraoral scanning, and conventional impression techniques for complete-arch implant rehabilitation: an in vitro comparative study

BackgroundTo compare the accuracy of photogrammetry, intraoral scanning and conventional impression techniques for complete-arch implant rehabilitation.MethodsA master cast containing 6 implant abutment replicas was fabricated. Group PG: digital impressions were taken 10 times using a photogrammetry system; Group IOS: intraoral scanning was performed to fabricate 10 digital impressions; Group CNV: splinted open-tray impression technique was used to fabricate 10 definitive casts. The master cast and conventional definitive casts were digitized with a laboratory reference scanner. For all STL files obtained, scan bodies were converted to implant abutment replicas using a digital library. The accuracy of a digitizer was defined by 2 main parameters, trueness and precision. "Trueness" was used to describe the deviation between test files and reference file, and "precision" was used to describe the closeness between test files. Then, the trueness and precision of three impression techniques were evaluated and statistically compared (α = 0.05).ResultsThe median trueness was 24.45, 43.45 and 28.70 μm for group PG, IOS and CNV; Group PG gave more accurate trueness than group IOS (P < 0.001) and group CNV (P = 0.033), group CNV showed more accurate trueness than group IOS (P = 0.033). The median precision was 2.00, 36.00 and 29.40 μm for group PG, IOS and CNV; Group PG gave more accurate precision than group IOS (P < 0.001) and group CNV (P < 0.001), group CNV showed more accurate precision than IOS (P = 0.002).ConclusionsFor complete-arch implant rehabilitation, the photogrammetry system showed the best accuracy of all the impression techniques evaluated, followed by the conventional impression technique, and the intraoral scanner provided the least accuracy.

The Accuracy Of Digital Versus Conventional Open Tray Implant Impression Technique, In Partially Edentulous Patients.

Abstract: Impression techniques using digital technology seemed to be studied with the accuracy planning to initiate acceptable prosthetic results in implant dentistry. In order to overcome these misfit, digital impression by means of an intra-oral scanner may assist. The purpose of this study was conducted to assess the efficacy of using digital impression technique compared to conventional technique Material and Methods: 8 patients were examined with a total of 22 implants placed, each patient had undergone two impression techniques: a digital impression: intraoral scan body, and a conventional impression: open tray impression, the total deviation between the two impression techniques was measured. This was done by scanning the scan body in patient mouth in group I and digitalizing the conventional open tray impression by scanning the scan body on the cast produced by the open tray in group 2. The scan body was replaced on the software (Exocad software) with custom made abutment and the deviation between the two groups was measured using (Geomagic Control X; 3D systems) GOM inspection software Results: Total deviation between groups, the open tray conventional impression was compared to hypothesized reference digital impression and were calculated using GOM inspect software. The total deviation was statistically significantly different among the studied groups. Conclusions: In partially edentulous patients, intraoral oral scanning using intra oral scan bodies improves over all accuracy, than conventional open tray impression technique.

Three-dimensional accuracy of innovative implant-level impression techniques with plastic snap-on impression copings.

Several studies have assessed the accuracy of the indirect snap-on impression technique. However, some impression techniques that utilize plastic snap-on impression copings have not yet been investigated. This study aimed to assess the three-dimensional (3D) accuracy of innovative implant-level impression techniques with plastic impression copings and the splinted open-tray technique with metal impression copings. This in vitro study used a reference model of the mandible with 4 parallel dental implants. Forty impressions were made with polyether impression material, using the splinted opentray technique with metal impression copings (SOM group), the non-splinted closed-tray technique with snap-on impression copings (NCS group), the non-splinted open-tray technique with snap-on impression copings (NOS group), or the splinted open-tray technique with snap-on impression copings (SOS group); n = 10 per group. Linear discrepancies in the inter-implant distances on the obtained casts were determined in the X, Y and Z axes with the use of a coordinate measuring machine. Subsequently, the 3D accuracy of each impression technique was calculated. Data was analyzed by means of the one-way analysis of variance (ANOVA) followed by Tukey's post-hoc tests. Among different impression techniques, the amount of linear discrepancy was significant only for the Z axis. The SOM, NOS and SOS groups showed less discrepancy in this axis as compared to the NCS group (p < 0.001). A significant difference was also noted in 3D discrepancy (p = 0.022), with the SOM group showing a significantly higher discrepancy as compared to the SOS group (p = 0.016). The 3D accuracy of the implant-level splinted open-tray impression technique with plastic snap-on impression copings was significantly higher than that of the splinted open-tray technique with metal impression copings.

Open tray impression technique using a silica-nylon mesh for splitting implants: a case report

This article describes an alternative open tray technique for implant impressions using a novel reinforced silica-nylon mesh covered with acrylic resin as a splitting system in assembling the abutment complex. The purpose of the procedure is to simplify the technique and improve the resin contraction during clinical procedure, and also optimizes and reduces the chairside time for the patient. The clinical report was supported by an in vitro study where an analysis tool, Strain Gauge Analysis, was used to prove the clinical effectiveness of the technique. The peri-implant strain was determined on polyurethane casts with the torqued prosthesis, and statistically there was no difference in strain under torque of transfers or in the final prosthesis. The nylon mesh attached to acrylic resin represents a promising option for open tray impression technique, creating a resistant union to transfer in an excellent procedure time.

Making an open-tray implant or abutment-level impression technique easier

Various methods exist for taking implant impressions. The open-tray or pick-up impression technique is one of the conventional methods for transferring the impression coping from the implant to the impression. In this method, a window directly above the implant is made in a stock or custom tray to allow access to the impression coping. Traditionally, the window is either left open, or closed with melted wax or foil. This technique tip describes a modification to create a stable and secure seal over the opening using rayon-based adhesive tapes. The benefits of this modification over the conventional open-tray technique are due to the enhanced adhesive quality of the materials to metal or plastic. Because there is less chance of impression material leaking from the tray window into the mouth, it is more comfortable for patients and less messy for clinicians. The benefit of this method over the closed-tray technique is the ability to feel for the head of the impression coping at the same time as making sure the impression material is in good contact with the underlying structures. It is easy to use, and efficient in terms of time and cost.

Use of aluminum foil to facilitate open-tray implant impressions

When the conventional impression technique is selected over digital optical scanning for multiple implants, the open tray impression technique has been recommended over the closed tray or transfer technique in situations where 4 or more implants are present.1,2 The open tray technique incorporates a large opening in the impression tray that accommodates the complete-arch impression copings.3 While loading the impression material into the tray, preventing the material from escaping through the opening is often difficult.

A Comparative Evaluation of the Positional Accuracy of Multiple Implants by Open Tray Impression Technique using Three Different Splinting Materials: An in vitro study

&#x0D; Aim: To comparatively evaluate the positional accuracy of multiple implants by open tray impression technique using three different splinting materials namely self-cure acrylic resin, pattern resin and flowable composite.&#x0D; Materials and Methods: An edentulous maxillary model was fabricated with heat-cure acrylic resin. Four dummy implants were placed bilaterally at canine and second premolar positions in the acrylic model, perpendicular to the horizontal plane and parallel to each other. Open tray impression copings were attached to dummy implants. The copings were splinted with dental floss onto which self-cure acrylic resin was added, which was sectioned and rejoined (for Group A). Similarly, pattern resin (for Group B) and flowable composite (for Group C) were used as splinting materials after sectioning and rejoining as previously described for Group A. Open tray impressions were made using polyvinylsiloxane impression material to obtain 10 casts for each group categorized according to the splinting material used. Interimplant distances were measured between implants on the master model and between the implant analogs in the retrieved casts in three different groups using a Coordinate measuring machine and a comparative evaluation of positional accuracy was done.&#x0D; Results: Splinting with materials of all three Groups showed minimal variation in positions of multiple implants and within clinical limits. Group B (pattern resin) had more accurate values similar to master model compared to Group A (self-cure acrylic resin) and Group C (flowable composite), although statistically insignificant. The results with Groups A and C were similar. No statistically significant difference was derived between the three different groups.&#x0D; Conclusion: It was concluded that all the three splinting materials evaluated in the study can be recommended as splinting material of choice for multiple implants using open tray impression technique.

Dimensional accuracy of vinyl polyether and polyvinyl siloxane impression materials in direct implant impression technique for multiple dental implants.

The present study compared the dimensional accuracy of vinyl polyether silicone (VPES) and polyvinyl siloxane (PVS) impression materials used for non-splinted (NS) and splinted (S) direct open-tray impression techniques for multiple implants inserted in simulated edentulous mandibles. A mandibular stainless steel model with eight internal connections for implant analogs was fabricated to simulate a clinical scenario. The acrylic resin splinted and non-splinted direct impressions were obtained for both VPES and PVS materials. Seventy-two cast samples were divided into four groups based on the impression techniques and materials used. The dimensional accuracies of the casts were measured in three different axes using a computerized coordinate measuring machine (CMM), and were statistically compared. The differences in the distortion values between the VPES and PVS impression materials were not statistically significant. Similarly, the differences between the splinted and non-splinted groups among the VPES and PVS materials were not statistically significant. The casts fabricated from VPS or PVS impression materials provide similar dimensional accuracy regardless of the implant splinting method.

Accuracy of 3D Printed Implant Casts Versus Stone Casts: A Comparative Study in the Anterior Maxilla

To conduct an in vitro comparison of the amount of three-dimensional (3D) deviation of 3D printed casts generated from digital implant impressions with an intraoral scanner (IOS) to stone casts made of conventional impressions. A maxillary master cast with partially edentulous anterior area was fabricated with two internal connection implants (Regular CrossFit, Straumann). Stone casts (n = 10) that served as a control were fabricated with the splinted open-tray impression technique. Twenty digital impressions were made using a white light IOS (TRIOS, 3shape) and the Standard Tesselation Language (STL) files obtained were saved. Based on the STL files, a digital light processing (DLP) and a stereolithographic (SLA) 3D printer (Varseo S and Form 2) were used to print casts (n = 10 from each 3D printer). The master cast and all casts generated from each group were digitized using the same IOS. The STL files obtained were superimposed on the master cast STL file (reference) to evaluate the amount of 3D deviation with inspection software using the root mean square value (RMS). The independent-samples Kruskal-Wallis test and Dunn's test with Bonferroni correction (for post-hoc comparisons) were used for statistical analyses. The Varseo S group had the lowest median RMS value [77.5 μm (IQR = 91.4 - 135.4)], followed closely by the Conventional group [77.7 μm (IQR = 61.5 - 93.4)]. The Form 2 had the highest mean value [98.8 μm (IQR = 57.6 - 87.9)]. The independent-samples Kruskal-Wallis test revealed a significant difference between the groups (p = 0.018). Post-hoc testing revealed a significant difference between Varseo S and Form 2 (p = 0.009). The casts generated from the Varseo S 3D printer had better 3D accuracy than did those from the Form 2 3D printer. Both the Varseo S group and the conventional stone casts groups had similar 3D accuracy. This article is protected by copyright. All rights reserved.

An in vitro study to assess the positional accuracy in multiple implants using different splinting materials in open-tray impression technique

Context: Numerous implant techniques have been suggested in the literature to obtain an accurate master cast. One of those is to splint the impression copings; however, many controversies exist in type of splinting materials used. Aim: The aim of this study is to evaluate and compare the positional accuracy in multiple implants using different splinting materials in open-tray impression technique. Settings and Design: The study design involves an in vitro study. Materials and Methods: An acrylic resin model of a mandibular edentulous arch was used as a reference model in which four 3.75 mm × 10 mm implant analogs were placed and sequentially numbered as 1, 2, 3, and 4 from left to right. Open tray impression copings were attached to each of them and were then splinted by three different materials and divided into three Groups as Group I, Group II, and Group III splinted with pattern resin, composite resin, and titanium wire, respectively. Five implant level impressions were made from each group and poured in Type IV dental stone. The implant analogs were transferred to the casts and inter-implant distances were compared to the reference model using the Coordinate Measuring Machine. Statistical Analysis Used: One-way ANOVA test was used as a test of significance. Results: The present study revealed that all the three splinting materials can be used for the accurate reproduction of spatial relationship. There was no significant difference between the centroids of implant analogs 1 and 2, 1 and 3, 1 and 4, 2 and 3, 3 and 4, and 2 and 4 of reference model with the master models. Conclusion: Clinically acceptable accuracy in transferring the position of implants to the master cast could be obtained from all the three splinting materials used. However, splinting of impression copings with titanium wire showed greatest accuracy.

Study the Effects of Bilateral Balanced Occlusion and Canine Guidance on Masseter and Temporalis Muscle Activity in Implant-Retained Overdentures Constructed with Open and Closed Tray Impression

The aim of the study was to investigate the effects of balanced occlusion and canine guidance on masseter muscle activity in implant- retained overdentures constructed with open and closed tray impression. Material and methods: For the current study Twelve completely edentulous patients were selected from the Outpatient Clinic of Removable Prosthodontic Department, Faculty of Dental Medicine, Al Azhar University (Assiut branch) according to special inclusion and exclusion criteria. All procedures were explained to all the patients and informed consent was assigned by each patient before the commencement of the investigation. All patients were divided into two groups; with the first group open tray impression techniques was used. While the second group used close tray impression techniques.For each group two dentures were constructed; the first denture was constructed with bilateral balanced occlusion, while the second denture was constructed with canine guidance.Conclusion: Successful implant overdenture has a positive effect on the masticatory efficiency regardless of the type of impression used. Masticatory efficiency improved with closed tray impression method together with bilateral balance occlusion had the best masticatory efficiency during chewing soft food or hard food than any other impression method (close-open tray impression) with any other occlusion (bilateral balance-canine guided occlusion) during chewing soft or hard food.

Three-Dimensional Accuracy of Conventional Versus Digital Complete Arch Implant Impressions.

The accuracy of digital impressions is still controversial for complete arch implant cases. The aim of this study is to compare the accuracy of different intraoral scanners with the conventional technique in terms of trueness and precision in a complete arch implant model. Eight implants were inserted asymmetrically in a polyurethane edentulous mandibular model with different angulations. A 3-dimensional (3D) reference model was obtained by scanning this polyurethane model with an optical scanner. First, digital impressions were made by using 3 different intraoral scanners: Carestream 3500 (DC), Cerec Omnicam (DO) and 3Shape Trios 3 (DT). Subsequently, a nonsplinted open tray impression technique was used for conventional impression group (C) and then the master casts were digitalized with a lab scanner. Each 10 STL files belonging to 4 different impression groups were imported to a reverse engineering program, to measure distance and angle deviations from the reference model. All statistical analyses were performed after taking absolute values of the data. After comparing the impression groups with one-way ANOVA, the trueness and precision values were analyzed by Tukey post hoc test and 0.05 was used as the level of significance. The mean trueness of distance was 123.06 ± 89.83 µm for DC, 229.72 ± 121.34 µm for DO, 209.75± 47.07 µm for DT, and 345.32 ± 75.12 µm for C group (p < 0.0001). While DC showed significantly lower deviation compared to DO and C, no significant difference was found between DC and DT. C showed the highest distance deviation significantly in all groups; and no significant difference was found between DO and DT groups. In angle measurements; the trueness was 0.26° ± 0.07° for DC, 0.53° ± 0.42° for DO, 0.33° ± 0.30° for DT, and 0.74° ± 0.65° for C group. There was no significant difference between the groups in terms of angular trueness (p = 0.074). In terms of the precision for distance, the results of DC 80.43 ± 29.69µm, DO 94.06 ± 69.96 µm, DT 35.55 ± 28.46 µm and C 66.97 ± 36.69 µm were determined (p = 0.036). The significant difference was found only between DT and DO among all groups. Finally, angular precision was determined to be 0.19° ± 0.11° for DC, 0.30° ± 0.28° for DO, 0.22° ± 0.19° for DT, and 0.50° ± 0.38° for Group C. No significant difference was found between the groups, in terms of angular precision (p = 0.053). All digital impression groups yielded superior data compared to conventional technique in terms of trueness. DC formed the impression group with the highest trueness in both distance and angular measurements. The results of this in vitro study suggest the use of intraoral scanners compared to the conventional impression techniques in complete arch implant cases with high angulations.