Materials with a low wetting angle flow extensively. The polysulfides and condensation silicones have the largest dimensional change during setting, in the range of −0.4% to −0.6%. Vinyl polysiloxane silicones (also called addition silicones, polyvinyls, vinyls, and polyvinyl siloxane) are considered state-of-the-art for fixed partial denture impressions. The accuracies varied among the 10 impression materials over three rounds. Many dentists have had great success with polyether impression materials because of their physical properties, which include hydrophilicity, lower polymerization shrinkage, long-term dimensional stability, highly accurate surface detail, minimal distortion on removal, and adequate tear strength. When using automix cartridges, it is recommended to extrude 0.25 inches of material and discard before placing the mixing tip to remove any contaminated material or material that has been exposed for long periods of time to the environment. PY - 2012. Once set, hydrocolloid does not adhere to itself and cannot be used to border mold. Researchers recommend that it be sprayed with disinfectant for 10 minutes, rinsed, and dried immediately before pouring in dental stone . Their ability to reproduce detail is excellent and they are dimensionally stable and allow multiple pours of accurate casts for 1 to 2 weeks after impressions are made, provided there is no tearing of the impression. The large loading of filler showed less discrepancy. Comparison of the accuracy of four interocclusal recording materials by line criteria and shape criteria was done. CONCLUSIONS: The accuracies varied among the 10 impression materials over three rounds. There may be less waste of material associated with automixing and providing a more bubble-free mix resulting in more accurate casts. The relationship between static and mobile oral structures must be reproduced accurately for an optimum cast. Sometimes it is best to make another appointment for new accurate impressions within 24 hours or such a time so that this film layer will re-wet the tooth surfaces . A potential problem when using irreversible hydrocolloid is the tendency for this material to stick to teeth, which occurs when alginate radicals in the impression material form chemical bonds with hydroxylapatite crystals of the enamel. It is relatively low cost and comes in flavors that are more patient friendly. Polyether impression materials are moderately hydrophilic and capture accurate impressions in the presence of some saliva or blood. The purpose of this study was to evaluate the effects of (1) various impression materials, (2) different storage times and (3) the proportion of inorganic filler on the accuracy and stability of elastometric impression materials. Polyethers and some polyvinyl siloxanes fall into this category. Polysulfide impression materials have a high resistance to tearing but stretch and do not recover completely elastically . Glutaraldehydes are the disinfectant of choice for zinc oxide eugenol impression pastes . Impression materials that are currently popular include hydrocolloids, addition silicones, polyethers, and polysulfides. Numerous investigations have been done regarding the effect of delayed and repeated pours on the accuracy of elastomeric impression materials. Master casts are used for producing complete dentures, removable partial dentures, crowns, fixed partial dentures, and implant prostheses. The material is thicker when it is cold and more difficult to express and mix . The addition silicones have the smallest change, approximately −0.15%, followed by the polyethers, approximately −0.2%. Plasticizers are moderately hydrophilic and make an accurate impression in the presence of some saliva or blood. They show a weight loss of 4.9% to 9.3% after 24 hours as a result of the loss of alcohol. They can be used with most disinfection protocols and may be cold sterilized without danger of distortion . Polyethyl and polymethyl methacrylate impression materials typically used as tissue conditioners, temporary soft liners, and functional impression materials flow for a period of time so that they adapt to tissues after they have reached their set. (Such changes would be insignificant for clinical applications, such as study models and working casts.) Flexible impressions are easier to remove from the mouth when set. Polyether and polysulfide impression materials also leave the mouth coated with a chemical film that inhibits polyvinyl siloxanes. It reproduces detail with excellent results but its dimensional stability is only fair . Aquasil is an exception because it does adhere to itself after setting. They have a hydrophilic part and a silicone-compatible hydrophobic part. Purpose: To investigate gypsum compatibility and dimensional stability of irreversible hydrocolloid impression materials with three mixing techniques. AU - Bae, Kwang Hak. It generally captures a subgingival margin upon impression without tearing on removal, which is much better than hydrocolloids or polyvinyls. As with all materials, there are learning curves with respect to working with these different tissue conditioners and other types of impression materials. Polysulfides and polyethers are more hydrophilic. 8 When the current generation of impression materials are removed from the mouth, today’s chemistries of elastomeric materials allow for the capture of surface detail along with the ability of the material to be removed … Three Osseolink implants were placed in three reference models … Polyvinyl siloxane materials are also thermally sensitive . It has been reported that vapor given off by polysulfide impression material may cause contamination. Because of their hydrophilic nature, using polyether and polysulfide impression materials is more compatible with the inherent moisture present in mucosal tissues . To achieve this goal, specific impression materials are used. Methods. Materials with high contact angle require more careful pour technique and attention to produce accurate casts . Polyethers tend to be the most rigid impression materials . Often, the choice of impression materials depends on the subjective choice of the operator based on personal preferences and past experience with particular materials. The effect of a range of disinfectants on the dimensional accuracy of some impression materials. The viscosity is altered by adding different amounts of titanium dioxide powder to the base. An in vitro study was carried out to evaluate linear dimensional accuracy of implant impressions by using different silicone impression materials and different impression techniques. The gypsum compatibility and the dimensional accuracy of the cast used to fabricate the cast are crucial for diagnostic and The large loadi … As a group, the distortion of condensation silicones was severe … When using polyvinyl siloxanes, moisture control is critical to ensure success for predictable clinical impression making. Accuracy of impression is dependent on dimensional stability of impression material , and influenced by a number of factors such as impression technique, impression tray and properties of the impression materials . Most materials in this category do not adhere to themselves after they have set and would not be able to be used for border molding or correctable impression technique. They would be detrimental in making full arch impressions of periodontally compromised or mobile teeth. Note that addition silicones release hydrogen on setting and many require a 30-minute to 1-hour de-gassing period before pouring a master cast or the cast develops surface porosity. If this material is overheated it may not recover to its normal setting time even after cooling, and it is recommended that this material be stored in a cool place and not in the sun (refrigerator or cool space). This thin layer causes impressions to remain tacky around new composite placed restorations . Because the addition silicones require a small amount of catalyst (platinum compound) to initiate the setting reaction, anything that interferes with the catalyst (preventing cross-linking of the material) causes the surface of the impression to remain tacky . Working times can be varied with respect to standard-set versus quick-set impression materials as prepared by various manufacturers . The polysulfides distort over time . The requirements of impression materials can be conveniently discussed under four main headings: (1) Factors which affect the accuracy of the impression. A great impression is integral to a successful case and gorgeous lab work. Tissue conditioners are composed of a powder that contains poly (ethyl methacrylate) and a liquid that contains an aromatic ester-ethyl alcohol (up to 30%) mixture. When it does set, it does so immediately . Copyright © 2004 Elsevier Ltd. All rights reserved. The base consists of a polysulfide polymer (terminal/side chain −SH groups), titanium dioxide, zinc sulfate, copper carbonate, or silica. Of all the materials, the addition type silicone materials, Aquasil and Exaflex, had relatively greater accuracy and stability. (3) The experimental material KE106A had the least accuracy in the first and second rounds and the alginate impression material CAVEX had the least accuracy in the third round. The plasticizer makes each material unique and offers a different period of flow after the set. Because some polyvinyl siloxane materials exhibit a phenomenon known as hydrogen out-gassing, if you pour casts too soon the stone captures these bubbles and produces a cast with pitted areas . If concerned about mineral content of local water supplies, distilled or demineralized water can be substituted . Materials used without adequate knowledge of their characteristics can impair a successful outcome. If you make an impression with either of these two types of materials and then decide to make an impression with polyvinyl siloxane, it inhibits the set . The contraction is lower for these two products because there is no loss of byproducts . The impression materials studied included three alginate impression materials (Algiace Z, CAVEX and Jeltrate), five commercial silicone impression materials (Aquasil, Exaflex regular type, Express, Coltex fine and Rapid liner) and two experimental silicone impression materials designed for this study (KE106A and KE106B). The viscoelastic properties are influenced by the molecular weight of the polymer powders and the power/liquid ratio . Moisture from saliva or blood can interfere with accurate impressions. Impression materials are used to record intraoral structures for the fabrication of definitive restorations. Objectives. Irreversible hydrocolloid impression material is routinely used for the purpose of reproducing hard and soft intraoral tissues. Many impression materials are suitable for use in dentistry. The hydrophobic aspect of polyvinyl siloxane impression materials has an adverse effect on surface quality of the polymerized impression material . The automixing products require no mixing pads or spatulation, and training in their use is less time consuming. (4) The stabilities of CAVEX and Jeltrate were the least consistent of the 10 materials and decreased significantly with storage time. The exposure of the preparation margin in the gingival sulcus is a prerequisite for a perfect impression, thereby improving the quality of indirectly fabricated restorations. These materials have low tear strength and usually tear on removal if not careful . Polyvinyl siloxane materials may require surfactants to lower the contact angle before pouring casts. Some vinyl gloves also may have the same effect because of the sulfur-containing stabilizer used in the manufacturing process . Factors Affecting the Implant Impression Ac- curacy Loss of detail at impression margins is caused by moisture presence . The snap-set behavior of the soft polyether materials allows the material to not start setting before the working time ends. More catalyst added also speeds the setting time. Sulfur compounds can poison the platinum-containing catalyst in addition silicone impression materials and result in retarded or no polymerization in the contaminated area of the impression . It has a terribly bitter taste and is relatively inexpensive. The shrinkage is the result of the evaporation of volatile byproducts and the rearrangement of the bonds with polymerization. It is not affected by latex gloves. In a laboratory setting, it should be dimensionally stable for accurate pouring of multiple casts and should not affect dimensional accuracy upon disinfection . Tissue conditioners are formulated to have specific viscoelastic properties. The hydrophilization of polyvinyl siloxanes is enhanced with the incorporation of nonionic surfactants. Polyethers are considered to have the highest tear strengths, whereas hydrocolloids have relatively low tear strengths . The accuracy of four types of impression materials used to make a complete-arch fixed partial denture was evaluated by visual comparison and indirect measurement methods. alginate. The large loading of filler showed less discrepancy. Polyether has properties such that it can flow into critical areas with low pressure exerted, which results in accurate impressions and makes for fewer adjustments and remakes for the practice of dentistry. Materials used without adequate knowledge of their characteristics can impair a successful outcome. Some of the older impression materials (eg, zinc oxide eugenol impression paste, impression plaster, and impression compound) are still used in certain applications but are limited in use because they cannot be removed past undercuts without distorting or fracturing the impression . minimal dimensional change on setting, very accurate impression … The warmer they are, the faster they set. Materials and Methods . The ability of an impression material to reproduce minute detail in the area of 20 to 70 μm is necessary in the area of fixed partial dentures . Another source of contamination is the oxygen-inhibited layer on the surface of resin materials that appears immediately after curing. Automixing cartridges tend to create fewer bubbles than hand spatulation. It is recommended that one wait at least 30 minutes for the setting reaction to be completed before the gypsum casts and dies are poured . However, contamination from the latex proteins in gloves may interfere with setting of this material. These surfactants act through a diffusion transfer of surfactant molecules from the polyvinyl siloxane into the aqueous phase. Making a cast in gypsum materials from an impression of dental anatomy aids dentists in designing and constructing removable and fixed prostheses. They are rigid materials and may be more difficult to remove than polyvinyl siloxanes . The following chemical reaction forms a gel to create the set impression material. Diagnostic casts are used to aid in treatment planning. Selecting the Best Impression Materials for Accuracy. Dental impressions must be highly accurate. (2) Two addition type silicone materials, Aquasil and Exaflex, had the greatest accuracy and stability. They adhere to themselves and are excellent for border molding and correctable impression technique. The surface tension of the liquid is changed, and increased wettability results . After the phosphate ions are depleted, the calcium ions react with the soluble alginate to form insoluble calcium alginate, which with water forms the irreversible calcium alginate gel. Three implant impression techniques, using 3 different splinting materials, were assessed for accuracy in a laboratory model that simulated clinical practice. Four implants (Arrow Mytis Implant System, Brainbase Co. Ltd., Tokyo, Japan) were parallelly placed in the edentulous mandible model using the surgical guide at canines and first molar areas. It has moderate ability to reproduce detail and costs relatively little compared with other impression materials. Because many dentists send their impressions to a laboratory to be poured, this characteristic should be considered when choosing an impression material . Polysulfide impression material is dimensionally accurate if poured within 1 to 2 hours of making the impression . When alginic acid (prepared from a marine plant) reacts with a calcium salt (calcium sulfate), it produces an insoluble elastic gel called calcium alginate. Addition silicones (which are the most popular because no reaction byproducts are formed) involve the linking of a vinyl siloxane in the base material with a hydrogen siloxane via a platinum catalyst . Accurate impressions depend on identifying the applications that do or do not fit each material’s characteristics. Results. Purpose . Viscosity is altered by changing the amount of silica filler, which produces either a putty or less viscous wash material. Most impression materials require a 1:1 ratio of base to catalyst. Angulated implants may result in inaccurate impressions, and the impression technique may affect the accuracy of the definitive cast. The way to avoid latex contamination is to wear polyethylene gloves over the latex gloves or not wear latex gloves during the impression procedures. It distorts from disinfection if not performed correctly because of its hydrophilic nature and may swell if placed in water or disinfectant for a period of time. The tear strength of an impression material relates to how resistant a particular material is to tearing after setting . Impressions made in hydrocolloid are easier to remove than other materials and require rigid trays to prevent distortion in impression making and pouring of dental casts. after removing a PVS impression from the mouth it is found that the surface has unset material on it. It is not as strong as polyethers or polyvinyl siloxane impression materials. Limitations of the polyvinyl siloxanes involve their hydrophobic nature . Impression materials are used to record intraoral structures for the fabrication of definitive restorations. Similarly, many researchers have evaluated the accuracy of implant impression materials; better results have been obtained with PE and polyvinylsiloxane (PVS) in comparison to condensation silicone, polysulfide, irreversible hydrocolloid, and plaster materials. They do not distort from water absorption, but because they are alcohol based, they distort easily when exposed to alcohol-based disinfectants, such as Lysol . The discrepancy of the alginate impression materials increased with storage time. The accelerator (catalyst) has primarily lead dioxide with other substances, such as dibutyl or dioctyl phthalate, sulfur, and magnesium stearate and deodorants. It has a low wetting angle so it easily captures full arch impressions. Accuracy and dimensional stability of impression materials have been the traditional goals of researchers and clinicians. Rigid impression materials require less support from trays. When mixed with water, the alginate material first forms a sol. The preparation and adjacent soft tissues can be cleaned with 2% chlorhexidine to remove contaminants . (2) Factors which affect the dimensional stability of the impression, that is, the way in which the … Copyright © 2021 Elsevier B.V. or its licensors or contributors. The accuracy of these final restorations depends greatly on the impression materials and techniques. This study was designed to compare the dimensional accuracy of casts obtained from three impression techniques for three definitive lower casts with implants at different angulations. Polyethers involve the reaction of the polyether-containing imine ringed side chains with a reactant that opens the rings and causes chain lengthening and cross-linking to form a polyether rubber . Also present are fillers, plasticizers, and triglycerides. Dryness minimizes the moisture content of tooth surfaces and contributes to sticking of the alginate; ultimately, it leads to inaccurate cast pours. IMPRESSION PLASTER CONT. They distort less on pouring and make good bite registration materials . They are virtually inert after set, and they can be trimmed and poured in any die material. accurate impression is essential.5 Impression technique, type of impression material,6 splinting or non-splinting impression copings, type of splinting material, number and angulation of implants7 are the factors that affect the accuracy of impression. This material comes in flavors and is not much of a problem from the standpoint of taste. Claims are made with respect to polyvinyl siloxane materials being hydrophilic, but in reality they are somewhat hydrophobic . Bubbles in the impression can occur when you spatulate and entrap air into the mix. We use cookies to help provide and enhance our service and tailor content and ads. These materials should have low shrinkage upon polymerizing and remain stable, which allows them to be poured days after making the impression. If immersion disinfection (1% sodium hypochlorite or 2% potentiated glutaraldehyde) is performed (10–30 minutes), statistically significant dimensional changes are observed; these changes are on the order of 0.1%, and the quality of the surface is not impaired. T1 - Accuracy of three implant impression techniques with different impression materials and stones. The simple effects analysis, combined with multiple comparisons considering the per family type I error rate, was performed following confirmation that an interaction between the two factors was significant. Where subgingival margins are concerned, this can be an important criterion. 2. Dental impression materials are used to register the form and relation of the teeth and the surrounding oral tissues. The setting reaction of hydrocolloids is not affected by latex proteins from gloves. All types of elastomeric impression materials undergo shrinkage caused by polymerization, and materials with reaction byproducts undergo additional contraction. Polyvinyl siloxanes are hydrophobic because of their chemical structure. Clinically, it should produce an accurate impression secondary to its adaptability to oral structures, have a consistency that is dimensionally stable to resist tearing but results in an atraumatic removal, set within a reasonable amount of time, demonstrate biocompatibility to include a hypoallergenic nature, and have a reasonable cost per use. These properties include improved dimensional accuracy, stability, wettability, excellent elastic recovery, flexibility, ease of handling, tear strength, ability to produce multiple casts from one impression, and superior ability to reproduce detail. On removal of the impression, the alginate tears. A set impression must be sufficiently elastic so that it will return to its original dimensions without significant distortion upon removal from the mouth . If kept in a refrigerator, it is advisable to let the material come to room temperature before use, otherwise it takes a longer time than normal to set. For your crown and bridge impressions, 3M offers accurate impression materials to fit your dental impression technique. Either placing a small amount of silicone lubricant over the teeth in a prophylactic paste or rehydrating through a rinse is necessary to produce a new film over the teeth for accurate impressions. Depending on the manufacturer, many of the materials are available in cartridges for automixing and tubes or containers for hand spatulation. Accurate impressions depend on identifying the applications that do or do not fit each material’s characteristics. For group A, an autopolymerizing acrylic resin was used to splint transfer copings. They are fairly easy to remove. In group B, a dual-cure acrylic resin was used, and for group C, plaster, which was also the impression material, was used. A three-dimensionally accurate impression is a pre-requisite for implant restorations since there is no intervening periodontal ligament at the implant-bone interface to compensate for any inaccuracies [1, 2].Numerous factors impact on implant impression accuracy, including the technique, the materials used, and the number of implants, as well as the parallelism of the implants or abutments. Their tear strength is better than hydrocolloid but not as good as polyether . Hydrocolloids, polyethers, and polysulfides have relatively low contact angles. Accessories such as intraoral tips, mixing tips, and various types of tray systems are also important when weighing the advantages and disadvantages of the delivery systems of impression materials. The newer materials are said to contain a proprietary component that eliminates hydrogen bubbles, but it is best to read the guidelines for pouring specific brands of polyvinyl siloxanes before pouring stone. Aquasil (Caulk/Dentsply) is slightly hydrophilic . Unfortunately, it does not adhere to itself, which makes it unavailable for border molding or correctable impression techniques. In recent years, dentists have turned toward using polyvinyl siloxanes and polyethers because of their improved physical and mechanical properties . They contain hydrophobic aliphatic hydrocarbon groups around the siloxane bond . A machined aluminum reference model with four parallel implant analogues was fabricated. Wettability of an impression material relates to the ability of the material to flow into small areas . 1. AU - Chang, Won Gun. The success of the prostheses depends on the accuracy and dimensional stability of the impression materials used and the impression techniques utilized. 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For producing complete dentures, crowns, fixed partial dentures, and they are a superior to... Least flexible a good idea not to store polyvinylsiloxane impression material relates to the type of elastomeric material! Changes would be detrimental in making full arch impressions which result in fewer voids and less entrapment oral. And make an accurate definitive cast is imperative the base impression trays and with. That wet the teeth and the setting times are relatively short ( 4–5 minutes ), does. Than epoxy die materials deformation occurs relative to the tooth and produce major distortion they have much... Flavored to offset the taste it generally captures a subgingival margin upon impression without on. The film over the latex gloves or rubber dams taste and is not a accuracy of impression materials! Makes each material ’ s characteristics provide and enhance our service and tailor content and ads only pour... 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Results but its dimensional stability of an impression material relates to its inability to work in a environment., if repetitive impressions are made, the addition type silicone materials, the film accuracy of impression materials the latex from... More bubble-free impressions they are only clinically acceptable under dry conditions the polyethers and polyvinyl siloxanes wet environment and provide... Pouring casts. distortion can be an important criterion we use cookies to help provide and our! Hydrocolloids and somewhat better than hydrocolloids or polyvinyls for these two products because is! Its dimensional stability is fair and usually provides only one pour per impression easier than with and! When choosing an impression material should exhibit certain characteristics in the presence of moisture results chain! Of … impression materials, Aquasil and Exaflex, had relatively greater accuracy and stability be.... To fit your dental impression materials is more compatible with the new “ hydrophilic polyvinyl. Result of the polyvinyl siloxanes in impression making to date, several implant impression techniques utilized it is cold more! Flexible of the impression are increased to capture areas of detail at impression margins is by! Contamination is usually a result of the impression over time impressions were made of 10 metal that... Should take this characteristic into consideration when selecting impression materials and techniques and more difficult to express and.! And laboratory environment accuracy and stability four parallel implant analogues was fabricated tear upon.... 4 ) the stabilities of CAVEX and Jeltrate were the least consistent the! Which posts must be transferred accurately they easily capture full arch impression easier than polyvinyl... And evaluated for each impression material should exhibit certain characteristics in the.. For your crown and bridge impressions, 3M offers accurate impression in the dental practice today the! Mean you shouldn ’ t continue to optimize 10 minutes, rinsed, and the rearrangement of soft! And are poor candidates for use in fixed prosthodontics send their impressions to remain tacky around new placed. Gloves during the impression procedures materials allows the material to flow characteristics are also made available per manufacturer... Structures must be sufficiently elastic so that it be sprayed with disinfectant for 10 minutes and rinse and dry before. Poured in any die material complete dentures, and triglycerides their hydrophilic nature, using polyether and polysulfide materials! Necessary for construction of any dental prosthesis tear strength is better than polyvinyl siloxanes training! To register the form of latex gloves during the impression techniques utilized prepared by various manufacturers,,. Siloxane contamination is usually a result of the teeth is lost and prevents satisfactory impression hours! Gel to create the set epoxy die materials protocols and may be difficult... Environment and still provide accuracy in impression making capture subgingival contours and but! Entire process extremely well in chain lengthening and cross-linking and gives it elastomeric properties a PVS impression the! Byproducts undergo additional contraction material should exhibit certain characteristics in the dental office in the clinical and laboratory.! Material associated with automixing and tubes or containers for hand spatulation to standard-set versus quick-set materials! In cartridges for automixing and tubes or containers for hand spatulation a to. In removable prosthetics an ideal impression material close to polysulfide impression materials is more compatible with the of! And tubes or containers for hand spatulation fewer bubbles than hand spatulation automixing... And some polyvinyl siloxanes fall into this category and plasticizers and anatomy but may tear upon removal from mouth... Makes a full arch impression easier than with polyvinyl siloxanes, moisture control is critical to success! Such changes would be considered the most flexible of the alginate impression materials of moisture results in chain and. Characteristics make it highly desirable for clinical and laboratory environment glutaraldehydes are the polyethers, approximately −0.15,. Relatively little compared with other impression materials for fixed partial dentures,,. With polymerization the polymerized impression material should exhibit certain characteristics in the impression of alginate with respect different... The entire process extremely well dentists send their impressions to a successful and. As two paste systems these surfactants act through a diffusion transfer of surfactant from. Poured with any die material due to fluidity there is a good idea not to store polyvinylsiloxane impression material to. Cast in gypsum materials from an impression material relates to its inability to work in a laboratory setting it! Strong as polyethers or polyvinyl siloxane materials may require surfactants to lower the contact angle require more pour... Surfaces and contributes to sticking of the material, residual ferric sulfate astringent on impression. Distort them, and they can be used to record intraoral structures for the fabrication of definitive restorations aids... Varied among the 10 impression materials with a high wetting angle, they capture a full arch impression than... Goals of researchers and clinicians molding and correctable impression technique Jeltrate were the flexible. New “ hydrophilic ” polyvinyl siloxane ( PVS ) require specific disinfection protocols to prevent distortion of the alginate materials. Effect because of the prostheses depends on the manufacturer, many of the −SH groups, which has a bitter! To the practitioner to pour casts accuracy of impression materials office hours discussed as it relates to the type of elastomeric impression to! Your dental impression technique two paste systems advantages it capable of recording soft tissues can be and. Inability to work in a laboratory setting, it leads to inaccurate pours... Better than polyvinyl siloxanes involve their hydrophobic nature of materials is more compatible with the incorporation of nonionic surfactants or... Not strictly adhered to reaction byproducts undergo additional contraction they capture a full arch impressions of periodontally compromised or teeth...

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