Silicone Impression Technique Research Articles

Investigating the implant position reproducibility of optical impressions obtained using an intraoral scanner and 3D-printed models fabricated using an intraoral scanner

PurposeThis study aims to examine the effect of the size of the intraoral scanning area on implant position reproducibility and compare the implant position reproducibility of plaster models fabricated using the silicone impression technique, the digital model of an intraoral scanner, and three-dimensional (3D)-printed models fabricated using an intraoral scanner.MethodsScanbodies were attached to an edentulous model with six implants (master model) and were scanned using a dental laboratory scanner to obtain basic data. The plaster model was fabricated using the open-tray method (IMPM; n = 5). The master model was then scanned in various implant areas using an intraoral scanner to obtain data (IOSM; n = 5); the scanning data of six scanbodies were used to fabricate the 3D-printed models (3DPM; n = 5) using a 3D printer. Scanbodies were attached to the implant analogs of the IMPM and 3DPM models and data were obtained using a dental laboratory scanner. The basic data and IMPM, IOSM, and 3DPM data were superimposed to calculate the concordance rate of the scanbodies.ResultsThe concordance rate of intraoral scanning decreased as the number of scanbodies increased. Significant differences were observed between the IMPM and IOSM data, and between the IOSM and 3DPM data; however, the IMPM and 3DPM data did not differ significantly.ConclusionsThe implant position reproducibility of the intraoral scanner decreased with an increase in the scanning area. However, ISOM and 3DPM may provide higher implant position reproducibility than plaster models fabricated using IMPM.

Silicone impression technique for proper-fitting mandibular complete dentures

総義歯最終印象の目的を顎堤および周囲組織との良好な適合の獲得としたときの下顎総義歯製作における効果的なシリコーン印象法について，印象の成否の評価基準を明確にしたうえで検討を行った．評価基準は，安定して機能している下顎総義歯群における適合検査の粘膜面から得た3 つの特徴的所見とした．印象面の評価のしやすさでは，単一シリコーン印象材による単層印象が最適と考え，Biofunctional Prothetic Syetem（BPS）にみる印象法を対照として検討を進めた．その結果，単層印象では維持不足に陥る傾向が認められ，それを補うには個人トレーの床縁設計が重要であることが分かった．また，中程度の流動性のシリコーン印象材を使用し，さらに，シリコーンと個人トレーの色の相性を考慮することで印象面の評価のしやすさが向上することが分かった．本研究により，義歯製作の全過程において適合検査の活用により3 つの特徴を共有しながら，下顎吸着メカニズムに則り製作された個人トレーを使用し，単一シリコーン印象材による単層印象を実践することが良好な適合の獲得に繋がるとの結論に達した．【顎咬合誌 40（3）:245-252，2020】

Evaluation of the quality of fixed prosthesis impressions in private laboratories in a sample from Yemen

BackgroundFixed prosthodontics require an accurate impression for the teeth and the area to be restored for the laboratory to fabricate the desired restoration without mistakes. This study evaluated the quality of impressions received by private laboratories for the fabrication of fixed prosthesis by describing the frequency of clinically detectable errors and by analyzing association between the various factors involved.Methods165 impressions were collected from four dental laboratories. Jaw involved, type of tray, size of tray, number of prepared units, type of impression materials, techniques and viscosity in case of elastomeric impressions and type of prosthesis requested were recorded. Data referring to errors and visible defects including errors in finish line, in preparation area, in silicone impression technique and blood in impression were also documented. Factors affecting errors present were also assessed. Association between dentist gender and experience years and impression errors was assessed. Chi square and Fisher exact tests used to examine the association between categorical variables and outcomes.ResultsThe total of error considering not immediately pouring as an error. Alginate was the most impression used. of impressions evaluated (50.9%), 97% were have at least one visible error; 92.1% had errors in finish line, 53.9% had errors in preparation area and (72.8%) of elastomeric impressions were have at least one error in technique. Blood in impression was detected in 52.1% of impressions. Significant association was found between material type and errors in finishing line and preparation area. Significant relationships were found between gender and errors in silicone impression technique (p < 0.05).ConclusionWithin the limitations of this study, high frequency of detectable errors was found in fixed prosthesis impressions received by private dental laboratories. This high frequency is of serious concern, as this will result in poor fitted fixed prosthesis provided to patients.

Comparative study of all-ceramic crowns obtained from conventional and digital impressions: clinical findings

To compare clinical aspects of all-ceramic crowns fabricated from conventional and digital impressions. Thirty patients with 30 posterior teeth with the need of a crown restoration were selected. Zirconia-based ceramic crowns were made using an intraoral digital impression system (TRIOS®, 3shape) and two-step silicone impression technique. Two external blinded operators evaluated the all-ceramic crowns. Five selection items were assessed of which four were clinical: "marginal fit," "occlusal contacts," "interproximal contact points," and "primary retention." Then, the last selection item "final selection" was assessed when the operators considering all the variables had to select which of the digital or conventional crown had the best clinical conditions. Data was analyzed using Kappa index test and the Pearson's chi-square test (α = 0.05). For the items marginal fit and interproximal contact points, moderate agreement between the two operators was described and significant differences were found between the two study groups. Conversely, for the variables primary retention and occlusal contacts, the agreement between the operators was fair and no significant differences were found. For the final selection, a substantial agreement was reached between the two operators and significant differences were found between the two groups (p &lt; 0.05). In most cases and in a significant way, the digital crowns had better clinical conditions according to both evaluators. The digital crowns were statistically superior for the interproximal contact points and marginal fit. For the variables occlusal contacts and primary retention, no difference between the two groups was observed. Digital intraoral impressions can be used for manufacturing ceramic crowns, with the same or better clinical results as conventional impressions.

Examination of the Position Accuracy of Implant Abutments Reproduced by Intra-Oral Optical Impression.

An impression technique called optical impression using intraoral scanner has attracted attention in digital dentistry. This study aimed to evaluate the accuracy of the optical impression, comparing a virtual model reproduced by an intraoral scanner to a working cast made by conventional silicone impression technique. Two implants were placed on a master model. Working casts made of plaster were fabricated from the master model by silicone impression. The distance between the ball abutments and the angulation between the healing abutments of 5 mm and 7 mm height at master model were measured using Computer Numerical Control Coordinate Measuring Machine (CNCCMM) as control. Working casts were then measured using CNCCMM, and virtual models via stereo lithography data of master model were measured by a three-dimensional analyzing software. The distance between ball abutments of the master model was 9634.9 ± 1.2 μm. The mean values of trueness of the Lava COS and working casts were 64.5 μm and 22.5 μm, respectively, greater than that of control. The mean of precision values of the Lava COS and working casts were 15.6 μm and 13.5 μm, respectively. In the case of a 5-mm-height healing abutment, mean angulation error of the Lava COS was greater than that of the working cast, resulting in significant differences in trueness and precision. However, in the case of a 7-mm-height abutment, mean angulation errors of the Lava COS and the working cast were not significantly different in trueness and precision. Therefore, distance errors of the optical impression were slightly greater than those of conventional impression. Moreover, the trueness and precision of angulation error could be improved in the optical impression using longer healing abutments. In the near future, the development of information technology could enable improvement in the accuracy of the optical impression with intraoral scanners.

Comparison of the accuracy of digitally fabricated polyurethane model and conventional gypsum model

PURPOSEThe accuracy of a gypsum model (GM), which was taken using a conventional silicone impression technique, was compared with that of a polyurethane model (PM), which was taken using an iTero™ digital impression system.MATERIALS AND METHODSThe maxillary first molar artificial tooth was selected as the reference tooth. The GMs were fabricated through a silicone impression of a reference tooth, and PMs were fabricated by a digital impression (n=9, in each group). The reference tooth and experimental models were scanned using a 3 shape convince™ scan system. Each GM and PM image was superimposed on the registered reference model (RM) and 2D images were obtained. The discrepancies of the points registered on the superimposed images were measured and defined as GM-RM group and PM-RM group. Statistical analysis was performed using a Student's T-test (α=0.05).RESULTSA comparison of the absolute value of the discrepancy revealed a significant difference between the two groups only at the occlusal surface. The GM group showed a smaller mean discrepancy than the PM group. Significant differences in the GM-RM group and PM-RM group were observed in the margins (point a and f), mesial mid-axial wall (point b) and occlusal surfaces (point c and d).CONCLUSIONUnder the conditions examined, the digitally fabricated polyurethane model showed a tendency for a reduced size in the margin than the reference tooth. The conventional gypsum model showed a smaller discrepancy on the occlusal surface than the polyurethane model.

Silicone impression technique for securing skin grafts in the cranio-facial area

Silicone impression technique for securing skin grafts in the cranio-facial area

Sudomotor function and sweat gland innervation in galanin knockout mice

The presence of galanin and galanin binding sites in sweat gland has been demonstrated previously. In order to investigate whether galanin can influence sweat gland function, we compared sweating induced in footpads of wild type and galanin knockout mice by cholinergic and thermal stimulation using the silicone impression technique. Pilocarpine injections resulted in a similar number of reactive sweat glands and non-significant difference in the amount of sweat secretion in wild type and galanin knockout mice. However, thermal stimulation led to a significant increase in the number of secreting sweat glands in galanin knockout mice. To further evaluate possible differences in the innervation of sweat glands that could explain differences in their secretory activity, immunohistochemical labeling of cutaneous and sudomotor innervations against protein gene product 9.5, vasoactive intestinal polypeptide and choline acetyltransferase in plantar pads was performed. Immunohistochemical analysis revealed no significant differences in the distribution and intensity of the innervations between wild type mice and galanin knockout mice. Although our results indicate normal cholinergic responses and innervation of the sweat glands in galanin knockout mice, they also demonstrate that galanin plays a role in regulating the sudomotor activity in response to thermal stimulation.

Accuracy of one-step versus two-step putty wash addition silicone impression technique

This study compared the accuracy of one-step putty wash with two-step putty wash impression techniques. Five addition silicone impression materials—Mirror 3 (MR), Mirror 3 Extrude (ME), Express (E), Permagum (P), and Absolute(A)—were tested. A stainless steel model containing two full-crown abutment preparations was used as the positive control. Five replications for one-step and two-step patty wash impressions of the master model were made for each test material. Accuracy of the materials was assessed by measuring six dimensions on stone dies poured from impressions of the master model. Accuracy of addition silicone impression material is affected more by material than technique. Accuracy of the putty wash one-step impression technique was not different from the putty wash two-step impression technique except at one of the six dimensions where one-step was more accurate than two-step. Mirror 3 putty wash two-step impression presented less distortion than Mirror 3 Extrude putty wash one-step or two-step impression.

模型‐埋没法によるポストの適合性に関する研究 印象法，専用液濃度および支台歯部位の相違による検討

Post core being used as an abutment tooth for pulpless tooth whose crown tooth substance is considerably damaged is indispensable. Its construction generally depends on indirect methods. There are two constructing techniques: to take wax pattern on an indirect working model using plaster in accordance with the normal method, and to invest wax pattern together with working model prepared by using die-investment (die-investing technique). The former has such demerits as to be difficult in wax pattern taking, the abutment tooth root canal being too narrow and long in shape to see directly, and wax pattern is liable to be deformed and damaged when it is taken out of the root canal. Contrarily the latter requiring no wax manipulation in the root canal, having the merit of improving the demerits of the former, is advantageous in the post core constructing technique.But in the present die-investing technique, the dimensional accuracy of the cast products is much influenced by the dimensional change in process of constructing working models, as it shows properties quite contrary to those of the conventional cast investment; large in setting expansion and small in thermal expansion. Consequently it is necessary to make out the phases of the dimensional change of working models, in case the die-investing technique is applied to the construction of post cores.We have hither to performed studies on models for outer cast products, using model investment, but no report has ever been published with regard to post cores, inner cast products, to be adapted in the root canal, and we consider it necessary to examine in order to construct post cores having preferable adaptability.The author, to find out the post core construting technique, taking advantage of the merit of die-investing technique, choosing upper left incisal, canine and second premolar as experimental objects, examines the effects of the difference in the impression technique and the special liquid concentration on the adaptability of post cores prepared for the respective abutment teeth. The results are as follows:1. Difference in impression materialsIn the case of silicone impression technique, as compared with in the case of agar-alginate combined impression technique, post cores showing a tendency to be large in the upper-lower, bucco-lingual and mesio-distal directions, preferable adaptability can be expected.2. Difference in special liquid concentrationPost cores show a tendency to be small in the upper-lower, bucco-lingual and mesio-distal directions in case the special liquid concentration is small.3. Difference in abutment tooth positions Some difference in the adaptability of post cores in the bucco-lingual and mesio-distal directions can be seen in the cases of incisal and canine, but there is little difference of it in both directions in the case of second premolar.4. Clinically, it is suggested that post cores having preferable adaptability can be obtained: by silicone impession technique with 50% special liquid used in the case of incisal abutment tooth; by agar-alginate combined impression technique with 100% special liquid used in the case of canine abutment tooth ; and by silicone impression technique with 100% and 50% special liquid and by agaralginate combined impression technique with 100% special liquid used in the case of second premolar abutment tooth.

A Study on the Relation between the Impression Pressure and Dimensional Accuracy in Silicone Impression Technique

A Study on the Relation between the Impression Pressure and Dimensional Accuracy in Silicone Impression Technique