IMPRESSION MATERIALS IN ORTHODONTICS.pptx

IMPRESSION MATERIALS IN ORTHODONTIC

1. GOOD MORNING

2. IMPRESSION MATERIALS Guided by : Dr Abhishek Roy PROFESSOR & HOD Presented by : DR. NABEEL AFTAB PGT 1 st YEAR Mithila Minority Dental College and Hospital, Laheriasarai , Darbhanga Department of Orthodontics & Dentofacial Orthopedics 2

3. Contents Definition I ntroduction History Ideal requirements Classification of impression materials Hydrocolloids Elastomers Causes for failure of impression R ecent advancements Conclusion References 3

4. DEFINITION “In dentistry, the impression is the negative replica of teeth and its supporting and surrounding structures.” 4

5. Introduction I mpression materials are used to make an accurate replica of oral tissues. • The area involved may vary from a single tooth to the whole dentition or an impression of an edentulous mouth . • Usually the impression material is carried to the mouth in a plastic state on a tray and removed from the mouth when the material has set. • The accuracy, detail and quality of the final replica is of greatest importance. 5

6. T here are wide range of impression materials having its own advantages and disadvantages. When making impressions for orthodontic cast the hard and soft tissues should be accurately reproduced. The casts should include the teeth, palate and the alveolar process to the base of vestibule and to the floor of the mouth 6

7. DENTAL IMPRESSION An Imprint or a negative likeliness of the teeth and or edentulous areas where the teeth have been removed, made in a plastic material which becomes relatively hard or set when it comes in contact with these tissues. Any substance or combination of substances used for making a negative reproduction or a replica of the oral tissues 7

8. HISTORY PHILIP PFAFFS (History 1756 ) WAS THE FIRST TO DESCRIBE TAKING AN IMPRESSION OF THE JAW DELABARRE ( 1820 ) INTRODUCED THE IMPRESSION TRAY HARLES STENT ( 1857 ) A LONDON DENTIST TESTED A COMBINATION OF DIFFERENT KINDS OF WAXES HARDENED AT ORAL TEMPERATURES . JOSEPH RICHARDSON ( 1860 ) SUGGESTED THE EARLY USE OF GUTTA PERCHA FOR OBTAINING IMPRESSION BECAUSE OF ITS ELASTICITY S. WILLIAM WILDING ( 1940 ) USED ALGIN AS DENTAL IMPRESSION MATERIAL S. L. PEARSON , ( 1955 ) LIVERPOOL UNIVERSITY DEVELOPED ELASTIC IMPRESSION MATERIALS FROM SYNTHETIC RUBBER AND RESIN BASES. 8

9. In orthodontic impression are primarily made to obtain CASTS, which in turn are used for STUDY PURPOSE FABRICATION OF APPLIANCES MAINTAINING RECORDS 9

10. Ideal Requirements of Dental Impression Materials

11. Pleasant taste, odor Not contain any toxic or irritating ingredients Have adequate shelf life for storage and distribution Be economical Be easy to use with the minimum equipment Have adequate strength so that it will not break or tear while removing from the mouth

12. 7 .Faithfully reproduce the tissues of mouth 8 . Readily disinfected 9. No release of gas during setting of impression or cast and die materials

13. CLASSIFICATION OF IMPRESSION MATERIALS

14. 1 . By generic chemical name : Silicone material or ZOE or commercial brand names. 2. By the manner in which they harden or set irreversible reversible -Plaster of Paris Thermoplastic Non thermoplastic - ZnOE -Impression -Agar -Alginate compound - Elastomers -Wax

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16. Mucocompressive Mucostatic According to the viscosity or tissue displacement Impression plaster - Impression AGAR Compound Alginate - Putty elastomers

17. I n Orthodontics we r equire impression materials that are elastic since we deal with dentulous patients The most commonly employed materials include I. Hydrocolloid – Agar Agar (reversible) - Alginate (irreversible) II. Elastomeric impression materials. 17

18. IRREVERSIBLE HYDROCOLLOID -ALGINATE (ADA  no 18) ‘Algin’ - a peculiar mucous extract yielded by algae (a brown seaweed) In England, “S. William Wilding” received the patent for alginate as impression material. 18

19. Currently, alginate is more popular than agar because It is easy to manipulate It is comfortable for the Patient It is relatively inexpensive and does not require elaborate equipment TYPES TYPES TYPE I – RAPID OR FAST SETTING TYPE II – NORMAL SETTING 19

20. APPLICATIONS OF ALGINATE most communally used for making impression for orthodontic study models. For duplicating models. 20

21. COMPOSITION NO COMPOSITION FUNCTION   Composition Function % Salt of Alginic acid Dissolves in water & reacts with calcium ions 15% . Calcium sulphate Reacts with pottasium alginate to form calcium alginate 16% Tri sodium phosphate Reacts in preference with calcium sulphate –retarder 2% Pottasium Titanium Gypsum hardener 3% Zinc oxide Filler 4% Diatomaceous earth Filler 60% Flavouring & coloring agents traces 21

22. SETTING REACTION: Alginic acid is a linear polymer of Anhydro- B-D mannuronic acid of high molecular weight Two main reactions occurs during setting: i ) 2 Na 3 PO 4 + 3 Ca SO 4 Ca 3 (PO 4 ) 2 + 3 Na 2 SO 4 ( Sodium phosphate) (Calcium sulphate) (Retarder) (Reactor) (CALCIUM ) (SODIUM ) PHOSPHATE SULPHATE ii) Sodium Alginate + Ca SO 4 + H 2 O Ca Alginate + ( CALCIUMSULPHATE ) Na 2 SO 4 ( Powder) (Reactor) (Gel)

23. MANIPULATION Dental alginates are often manually mixed, but proprietary mechanical mixing devices are available. Alginate is supplied as a powder with a measuring scoop and a cylindrical cup for measuring water. The recommended powder-to-water ratio is usually 1:1 but is set by the manufacturer. Manual mixing is performed by adding the measured powder to a flexible rubber bowl and subsequently adding the corresponding amount of water. Mixing must be rapid, wiping or stropping against the side of the rubber bowl with a spatula. The final mixture must have a creamy consistency but should not fall from the spatula when lifted . The mixing time is important. Generally, 45 to 60 seconds is sufficient; total mixing time is dictated by the brand and type of alginate and a standard or fast set. The mixing time for regular alginate is 1 minute , and fast-set alginate should be mixed for no more than 45 seconds . The time must be carefully monitored; undermixing and overmixing affect the strength of the set impression.  23

24. Manufacturers have introduced a " dustless" alginate designed to reduce the dust encountered ; the powder is thicker and less prone to become airborne . In addition, color indicators have been added to some formulations to identify setting reactions, allowing the operator to decide when to proceed to the next step of impression-making. Semiautomatic mechanical mixing devices, available since 1978, create a less viscous mixture with fewer bubbles . Mechanical mixing may also improve the compressive strength . Water : powder 1:1 Mixing time :- 45-60 sec 24

25. 25 Types Mixing time Working time Setting time I- Fast set 45 sec 1.25 mins 1-2 mins II- Normal set 60 sec 2 mins 2 - 4.5 mins Control of gelation time: By manufacturers : by adding retarders By Dentist - Cold water : Longer is the gel n . time - Warm water : Shorter is the gel n . time

26. Selection of tray: The beginning of good impression starts with the selection of the correct stock tray. Tray is a device that is used to carry, confine and control impression material while making an impression. The space available in the mouth for upper impression is studied carefully by observation of the width and height of the vestibular spaces with mouth partly open. And in the lower the general form and size of basal seat is studied.

27. Advantages: Easy to mix and manipulate. Minimum requirement of equipment. Accuracy (if properly handled) Low cost Comfortable to the patient Hygienic (as fresh material is used for each impression) Disadvantages: Cannot be electroplated. Distortion occurs easily Poor dimensional stability (poured within 15 min.) Poor tear strength

28. 29 Flexibility ADA specification permits a range of 5% to 20% at a stress of 1000 gms /cm2 and most alginate have a typical value of 14%.

29. 30 Strength The compressive strengths range from 5000 – 9000 gms /cm². The Tear strength vary from 380- 700 gm/cm. •

30. ACCURACY ALGINATES are sufficiently flexible to record fine detail in the mouth. During setting of the material it is important that the impression should not be moved. The reaction is faster at higher temperature and so the material is contact with the tissues sets first. Any pressure on the gel due to movement of the tray will set up stresses within the materials which will distort the alginate after its removal from the mouth The material is sufficiently elastic to be withdrawn over undercuts. 31

31. SHELF LIFE Alginate impression material deteriorates rapidly at elevated temperature and The material should be stored in cool dry place.(not above 37c) The lid of bulk package can , must be replaced after every use, so as to minimize moisture contamination Stock only for 1 year 32

32. DIMENSION STABILITY A lginate impression loses water by evaporation and shrinks on standing in air If it is placed in water it absorbs water and swells .Therefore, cast should be poured immediately after making the impression. If storage is unavoidable keeping in a humid temperature of 100% results in least dimensional changes. BIOLOGICAL PROPERTIES Some of silica particles present in dust are of possible health hazards. Presently some manufacturers supply “Dust free” alginate. 33

33. Dustless alginate:- Many materials have now been formulated which gives off little or no dust particles, so avoiding dust inhalation. This can be achieved by coating the material with a glycol Siliconised alginates:- Two pastes alginates have been developed, which incorporate silicon polymer component. These materials have superior resistance to tearing compared to unmodified alginates. However dimensional stability is reported to be poor A combination r eversible hydrocolloid / alginate impression technique has been improved. 34

34. Modified alginates Flourides or silicofluorides to improve surface of stone model(hexafluoro titanate in alginoplast and xantalgin ) Chlorhexidine added to alginate powder ( hydrogum plus chlorhexidine) inactive bacterial microorganism. Mint and vanilla flavour ( orthoprint , formula 1) flavoured drops available(TOC) Zhermack vanilla flavored orthoprint is antinausea. 35

35. TYPES OF ALGINATE FLAVOURINGS There are three principal types of flavorings which are as follows:- Natural flavoring substances are obtained in their natural state from plant or animal raw materials, or by their physical, microbiological or enzymatic processes. Nature identical flavoring substances are synthesized, but are chemically identical to a substance found in nature. Artificial flavors, are synthesized and are not identical to any natural products. 36

36. T ray adhesive for alginates Come in liquid or aerosol presentation. Solvent is also available for cleaning metal trays after use. INDICATIONS Fix Adhesive – Liquid and Fix Adhesive – Spray are tray adhesives for alginate impression materials. Fix Solvent is used to remove Fix Adhesives from the impression tray after impression taking and casting. CONTRAINDICATIONS Use in patients or by persons with a known allergy to diethylenetriamine or any other components of the products. Kerr adhesive for silicones 37

37. IT is essential that impression materials adhere firmly to the impression trays. This can be achieved by either perforations or by the use of adhesives. Adhesive solutions are needed for alginates, polysulphides and silicones. Adhesives for alginates are solutions of resins in alcohol, they are supplied in a bottle with a brush or an aerosol spray. Polysulphide adhesives are rubber solutions in acetone. Examples of silicone adhesives are isopropylalcohol or amylacetone 38

38. Impression trays they are used to carry the impression material to the mouth in its plastic state till it sets 39

39. PERFORATED stock NON PERFORATED trays custom 40

40. Requirements of stock impression trays: Tray must be rigid. Flexible trays cause distortion of the impression. Dimensional stability. Tray should maintain its shape throughout the impression making. It should be smooth to avoid injury to oral tissues. It should provide uniform space for impression material. It should not distort the vestibular areas. Alkhafagy , Mohammed. (2020). Prosthodontics Impression trays. 10.13140/RG.2.2.19756.62082. 41

41. Disposable impression trays The disposable tray can be used for patients with transmissible diseases. It is bio-degradable. Reduces cross contamination. No need for auto- claving . It is biocompatible with oral cavity. The does not injure the soft tissue. Cost effective. PLASTIC AND METAL FREE DISPOSABLE DENTAL IMPRESSION IMPRESSION TRAYS MADE WITH PAPER 42

42. Maxillary tray The tray must completely cover the tuberosity Must be 4mm wider than the most apical portion of the alveolar process at the molar region. The tray must cover the anteriors with the incisors contacting the flat portion of the tray about 4 mm from the raised palatal part of the tray. 43

43. Mandibular tray The tray should cover all the teeth as well as the retromolar pad The tray should be 4-6 mm wider than the buccal and lingual portion of the anterior teeth 44

44. Modification of the tray Modification of the tray may be done using modelling wax when the t eeth are in extreme malposition or the arch is abnormally shaped, soft wax may be added to the impression tray. For example: to carry the impression material well up into the vestibule in Class II Division 1 In case where patients have high arched palates it is advisable to place wax in relation to the palatal aspect of the tray to ensure accurate recording of the palate and minimal wastage of the material. The wax has the advantage of reducing the pressure of the impression tray metal rim on the displaced tissue during the Impression taking technique 45

45. Preparation of the patient explain the procedure to the patient in the simplest of terms so that the patient is aware of the procedure and therefore the   fear of the unknown is over come. Seat the patient upright so as to prevent the gagging due to the backward flow of the excess material into the throat advice the patient to breath through the nose and in case of gagging try and distract the patient’s attention and ask the patient to look down wards. Prior to making the impression it is advisable to ask the patient to rinse the mouth with pre-impression mouth wash To Removes the debris To Reduce the surface tension of the teeth and tissues. 46

46. PRACTICE The placement of the empty tray into the patient’s mouth Assume the correct operator positioning Maxillary impression - 11 o’ clock Mandibular impression - 7 o’ clock 47

47. Sequence of impression making It is advisable to make mandibular impression  first as there is less chance of the patient to gag . This allows the patient to become accustomed to the taste and the feeling of the material in the mouth which in turn reduces the chances of gagging while making an impression of the maxillary arch. 48

48. Seating the impression tray – mandibular impression operator position at 7 O’clock Patient seated such a way that the occlusal plane placed parallel to the floor. Use the thumb and the index finger of the free hand to retract the cheek. Grasp the handle of the tray and rotate the tray into the mouth by using the front of the tray to deflect the other cheek. once inserted straighten the tray so that the tray is in line with the patient’s midface Note the position of the tray in relation to the anteriors . Using the index finger of both the hands press the tray downwards lightly and evenly over the mandibular arch until resistance is felt. 49

49. manipulate thepatients cheeks and lips to create a more detailed anatomy of the facial and vestibular area. Ask the patient to raise the tongue and then move it from side to side. Allow the material to set and then remove. Using a firm grip on the tray handle, use a side ways lifting motion to remove the tray. 50

50. Maxillary impression operator position at 11 O’clock position Patient seated such a way that the occlusal plane placed parallel to the floor. A blob of material may be placed in the palatal vault of the patient just behind the incisors, to eliminate the trapped air and to ensure the faithful reproduction of palatal tissue Use the thumb and the index finger of the free hand to retract the cheek. the tray is rotated into the mouth once again using the front of the tray to deflect the other cheek. Once inserted straighten the tray so that the tray is in line with the patient’s mid face . Begin to apply light pressure upwards till the light resistance is felt 51

51. initial seating the posterior region of the tray and subsequently the anterior part of the tray allowing the material to flow over the molars. Retract the upper lip as the tray is seated. This allows the material to flow and displace any air which might otherwise cause voids. Hold the tray in place till the material is set. To remove the impression , lift lips and cheek away with fingers to break the seal ,grasp handle pull tray away from teeth with quick motion 52

52. Impression for a functional appliance Impression for functional appliance fabrication differ some what from those for orthodontic diagnostic cast Areas where appliance components will contact soft tissue must be clearly delineated. Most appliances use contact with lingual mucosa to stimulate forward posturing,The impression must include the alveolar process below the lower molars if long lingual flanges are employed. the impression must not stretch and excessively displace the soft tissues in an area of contact with appliance.This is critical when lip pads and buccal shields are planned. To much extension of impression will result in pads and shield are too long and will cause soft tissue irritation and ulceration when the appliance is worn 53

53. Disinfecting the impression Disinfection of impression is a concern due to viral diseases such as Hepatitis B,A I D S and herpes simplex • Gently rinse the impression under the tap water to remove any debris that may be retained in the impression. • Gently shake the excess water. • Spray the entire impression with an O.S.H.A. (occupational health and saf ety administration) approved disinfecting solution. OR May immense the impression in a disinfectant such as : gluteraldehyde solution : iodophors :1:10 dilution of sodium hypochlorite :synthetic phenols • Rinse again 54

54. Criteria for accessing the impression Lack of voids. No distortion , clear and distinct impression Adequately extended. Free of debris and extraneous material. Adequate details and all structure must be recorded. Stable material which is sufficiently attached to the tray. 55

55. Causes of failure Grainy material Improper mixing Prolong mixing Undue gelation Water : powder ratio too low Tearing Inadequate bulk Moisture contamination Premature removal from mouth Prolong mixing 56

56. External bubbles Undue gelation, preventing flow Air incorporated during mixing irregular voids Moisture or debris on tissue Rough and chalky stone model Inadequate cleansing of impression Excess water or potassium sulfate solution left in impression Premature removal of model Distortion •Impression not poured immediately •Movement of tray during gelation • Premature removal from mouth 57

57. Introduced by “ Alphous poller of Vienna ” in 1925 Adopted commercially as “ Dentacol ” in 1928 It was the first successful elastic impression material Agar is an organic hydrophilic colloid extracted from “ Seaweed” It is a sulphuric ester of a linear polymer of galactose Though highly accurate, it has been largely replaced by alginates and elastomers due to its cumbersome manipulation Reversible hydrocolloids agar agar ( ada no:-11)

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59. 60 INGREDIENTS FUNCTION COMPOSITION AGAR BASIC CONSTITUENT 13-17 BORATES STRENGTH 0.2-0.5 SULPHATES GYPSUM HARDNER 1.0-2.0 WAX FILLER 0.5-1.0 THIXOTROPHIC MATERIAL THICKNERS 0.3-0.5 WATER REACTION MEDIUM BALANCE   ALKYL BENZOATE PRESERVATIVE 0.1%

60. The Material is supplied as: Gel in collapsible tubes (for impressions) A number of cylinders in a glass jar (syringe material) In bulk containers (for duplication) Manipulation: Agar hydrocolloid requires special equipments Hydro colloid conditioner Water cooled rim lock trays

61. Conditioner Consists of: Boiling or liquefaction section: 10 mins in boiling water (100 C). Storage section: 65-68 C is ideal it can be stored till needed Tempering section: 46 C for about 2mins

62. WATER COOLED RIM LOCK TRAYS

63. FINAL IMPRESSION WITH AGAR

64. Advantages: Hydrophilic Impression material Good elastic properties, Good recovery from distortion Can be re-used as a duplicating material Long working time and low material cost No mixing technique High accuracy and fine detail recording Disadvantages: Extensive and expensive equipment required It can not be electroplated Impossible to sterilize for reuse Low dimensional stability & tear resistance

65. Uses of Agar: Widely used at present for cast duplication For full mouth impression without deep undercuts As tissue conditioner Was used for crown & bridge before the advent of elastomers

66. Laminate technique or agar-alginate combination technique Injecting syringe agar material onto the prepared tooth Placing an impression tray with alginate over the injected syringe agar Wet field technique Area to be recorded is flooded with warm water Syringe agar material – quickly & liberally over prepared tooth Immediately, tray agar placed over the syringe agar Hydraulic pressure

67. PROPERTIES Permanent deformation ADA specification requires that the recovery from deformation be greater than 96.5% after the material is compressed 20% for 1 sec FLEXIBILITY- 4-15% STRENGTH- 8000gmcm² TEAR STRENGTH- 800-900gm/cm Compatibility with gypsum-more compatible with gypsum material AGAR impression are best stored in 100% relative humidity if models cannot prepared immediately BIOCOMPATIBILITY Thermal injury from reversible hydrocolloid as a result of improper tempering or faulty equipment during impression making 68

68. COMPARISON BETWEEN HYDROCOLLOIDS Properties Agar Alginate Flexibility 20 % 14 % Elasticity & elastic recovery 98.8 % 97.3 % Reprod n . of details 25 um < agar Tear strength 715 gm/cm 2 350-700 gm/cm 2 Comp. strength 8000 gm/cm 2 500-8000 gm/cm 2 Dim l . Stability Better Poor Reuse Possible Not possible Manipulation Conditioner & rim lock trays Normal trays

69. DUPLICATING MATERIAL Alginate and Agar –Agar may be used successfully as a duplicating material. In this way multiple casts can be duplicated from a single master cast, which may have been formed using some other material. This process is essential in ones orthodontic practice as it enables the use of one master cast to form several casts subsequently. 70

70. IMPRESSION WAX - Waxes were first used in dentistry in the 18 th century for the purpose of recording impressions

71. TYPES - Dental waxes are classified as: 1) Pattern wax 2) Processing wax 3) Impression wax - Impression wax is of 2 types : 1) Corrective wax 2) Bite registration wax

72. COMPOSITION - Waxes used in dentistry may be composed of natural and synthetic waxes, gums, fats, fatty acids, oils, pigments of various types. - Particular working characteristics of each dental wax achieved by the blending of appropriate natural & synythetic waxes & resins & other additives .

73. Bite Registration Wax - Bite registration wax is used to articulate models of opposing quadrants. - Bite registrations frequently are made from 28 gauge wax sheets or from hard baseplate wax, bite waxes are formulated from beeswax or hydrocarbon waxes such as paraffin or ceresin. - Certain bite waxes contain aluminium or copper particles. - The flow of several bite waxes at37ºC ranges from 2.5% to 22%indicating that these waxes are susceptible to distortion on removal from mouth

74. USES 1) Used in small quantities to fill in impressions in areas of insufficient material 2) for bite registration, mixture of border corrective & denture corrective waxes is used in patients with heavy masticatory musculature 3) For corrective impressions of free- end saddle areas of partial dentures

75. INELASTIC IMPRESSION MATERIALS

76. Impression compound: Rigid reversible impression material sets by temp change Primary impression in edentulous mouth. Was formerly used in fabrication of chin cups & head straps

77. Types: ADA specification No. 3 TYPE – I IMPRESSION COMPOUND - Primary impression - individual tooth impression TYPE - II TRAY COMPOUND - Border moulding - Check undercuts in inlay - Make a special tray

78. COMPOSITION: Ingredients Parts 1) Rosin 30 2) Copal resin 30 3) Carnauba wax 10 4) Stearic acid 5 5) Talc 75 6) Coloring agent Appropriate

79. CLINICAL PRESENTATION Supplied in rect or circular sheets 5-7.5cm length &0.65cm in thickness For copper band imp of inlays and crowns, material is supplied in stick form

80. Advantages 1) simple & easy to manipulate 2) economic 3)can be reused 4) compatible with gypsum Disadvantages 1) poor surface details 2) poor dimensional stability 3) compresses tissues

81. Uses: 1) primary imp in complete denture 2) indivisual tooth imp for die preparations 3) border moulding during secondary imp 4) checking undercuts in inlay prepaations 5) special trays 6)chin imp-used as special tray

82. ZINC OXIDE EUGENOL PASTE In orthodontics , for luting brackets

83. Composition: Base - Zinc oxide 87 % - Mineral oil 13 % Catalyst - Eugenol 12 % - Poly rosin 50 % - Filler (Silica) 20 % - Lanolin 3 % - Resinous balsam 10 % - CaCl2 5 %

84. Setting reaction: Acid-base reaction ZnO + H2O → Zn (OH)2 Zn (OH)2 + 2HE → ZnE2 + 2H2O (Base) (Acid) (Zinc eugenolate ) Working time - 1 min Setting time - 10-15 mins

85. Non eugenol pastes - Occasionally, eugenol may promote an allergic response in some patients . There may be a stinging or burning sensation when eugenol contacts soft tissues. - Alternative non-eugenol materials are based upon the reaction between zinc oxide and a carboxylic acid such as orthoethoxybenzoic acid , to form an insoluble soap (saponification reaction). The carboxylic acid may be present as a liquid or as a powder dispersed in a medium such as ethyl alcohol. ZnO + 2RCOOH (RCOO) 2 Zn + H 2 - The reaction is not greatly affected by temperature or humidity.

86. Causes for failure of impression 88 GRAINEY MATERIALS Inadequate boiling Storage temperature too low Storage time too long Separation of tray and material Water soaked layer of tray material not removed Tearing Premature gelation Inadequate bulk Premature removal from mouth Material partially gelled when tray seated External bubbles Gelation of syringe material preventing flow

87. Irregularly shaped void Material too cool or grainy Rough and chalky stone model Rough and chalky stone model 89

88. REFERENCES PHILIPS of dental materials XI Edition Nandini V V , Venkatesh K V, Nair K C. Alginate impressions: A practical perspective. J Conserv Dent 2008;11:37-41 Gupta R, Brizuela M. Dental Impression Materials. 2023 Mar 19. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan–. PMID: 34662010. : Aditya Jain et al. Preference of flavours in alginate impression materials among dentists. Int J Prostho Rehabil 2023 Alkhafagy , Mohammed. (2020). Prosthodontics Impression trays. 10.13140/RG.2.2.19756.62082. Dilip A, Gupta R, Geiger Z. Dental Alginate Impressions. [Updated 2023 May 30]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK470480/ 90

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