custom tray.pptx

an essential step in complete denture construction

1. Custom ( Special ) T ray

2. Secondary impression 1- Construction of custom tray 2- Border molding + impression Laboratory step Clinical step Laboratory step 3- Master cast

3. Custom ( Special ) Tray Definition : Is an individualized tray made from a cast recovered from a preliminary impression.it used in making a final impression.

4. Custom tray Criteria for Special tray construction : 1 . The tray should retain its shape throughout the impression procedure and pouring of impression. 2 . The borders must be under extended (2 mm ) from the vestibular . 3 . The tray should be simple to construct in minimal amount of time at reasonable cost. 4 . The tray should be rigid and of sufficient thickness (2-3 mm) that it will not fracture during its use.

5. 5 . The tray must have a handle for manipulation and the handle (L-shape) must not interfere with functional movement of the oral structures. 6 . The tray must be smooth on its exposed surfaces, and should have no sharp edges which would injury the patient . 7 . The tray should simulate the finished denture in size and shape .

6. Advantages of special trays 1- More accurate impression. 2- less impression material required ( economy). 3- provides even thickness of impression material . 4- The work with special tray is more easier & quicker than stock tray. 5- Special tray is more accurately adapted to the oral vestibules. 6- Special tray are less bulky than stock tray ( comfortable for the pt ). 7- it allows minimum thickness of imp. M.

7. Types of custom trays the primary considerations are the amount of undercut present and whether any areas of the mucosa are mobile or unsupported : 1- Close-fitting trays. 2- Spaced trays( with or without stoppers). 3- Windowed trays.

8. Function of spacer 1- The spacer allows the tray to be properly positioned in the mouth during border molding procedure. 2- To allow the impression to have an even thickness of impression material. 3- Prevent distortion of the material at final stage.

9. Material used in custom tray construction

10. Custom impression tray fabrication for upper and lower edentulous arches Step I : Outline of sulcus, relief & block out , custom tray border, wax spacer and tissue stops . Step II: Adaptation of wax spacer . Step III : 1- Fabrication of resin custom tray . 2- Fabrication of shellac custom tray.

11. Step I: Outline of sulcus: is marked in the preliminary cast with a black colored pencil in the upper and lower edentulous casts. Outline Custom tray border: The periodontal probe is placed in the sulcus and the 2 mm marking is done on the cast.

12. Tray outline done with the probe. A . labial and buccal sulcus a 2 mm markings are done on the cast with the probe along the with blue pencil .

13. Outline of tray border in the posterior area. B. The posterior aspect of the maxillary cast is drawn at least 1 mm beyond the posterior vibrating line of posterior palatal seal area ( post . Fovea palatini )( line extended from hamular notchs ). Outlining the sulcus Outlining the custom tray borders Wax spacer + tissue stops

14. Outline of the wax spacer: with a red- colored pencil t he spacer outline is done at a level of 2 mm short of the tray outline . A- in the maxillary cast: the posterior aspect of it is limited to the anterior vibrating line of the PPSA. B- In the mandibular cast: the buccal shelf area is not included in the spacer design.

15. Outline of tissue stops: In the maxillary cast: Four tissue stops are outlined. two in the anterior canine region and two in the posterior molar region. A 4 × 4 mm square is outlined with a red- coloured pencil. In the mandibular cast: two tissue stops are outlined in the anterior canine region only.

16. Function of Tissue Stops 1- To orient the tray . 2- For uniform thickness of the impression material.

17. Step II: Adaptation of wax spacer A- In the maxillary cast : 1- A half sheet of modelling wax is softened over a Bunsen burner and is adapted on the cast without any wrinkles.

18. 2- The wax spacer is trimmed on the cast to the derived outline with a blade . The tissue stop area is also cut along the outline drawn of 4 × 4 square dimensions.

19. 3- The outline of wax spacer is done at a level of 4 mm short of the sulcus and in the posterior aspect is limited to the anterior vibrating line.

20. Adaptation of wax spacer B- in the mandibular cast: Same as in maxillary cast except in the tissue stop area is cut along the outline drawn of 4 × 4 square dimensions + the wax spacer is not included in the buccal shelf area. the relief areas are covered with the wax spacer. *To this step the same for close fit and spaced special tray. Severe undercuts should be blocked out using wax.

21. Fabrication of resin custom tray Armamentarium: 1 . Maxillary and mandibular preliminary edentulous cast 2. Three coloured pencils 3. Modelling wax sheet 4. Wax carver 5. Wax knife 6. BP handle and blade no. 15 7. Separating medium like sodium alginate solution 8. Brush 9. Dappen dish 10. Self-cure resin 11. Cellophane sheet 12. Template 13. Roller or a glass plate 14. Porcelain cup with lid 15. Micromotor 16. Tungsten carbide bur 17. Sandpaper and mandrels

22. Step III: 1- Fabrication of resin custom tray The technique of fabrication of resin custom tray can be done by two Methods: 1. Finger adapted method. 2. Sprinkle on method.

23. 1- Finger adapted method is the most widely used technique of making impression trays . 1- A separating medium of sodium alginate (cold mould seal) is applied on them cast with a brush in unidirectional stroke ….. to aid in easy removal of the tray from the cast.

24. 2- The resin is mixed in the form of dough and is rolled to the desired thickness ( 2mm ) by either pressing the material between two glass slabs or by plastic roll .

25. 3- adapted to the cast with finger pressure over the cast from the center to the periphery to prevent the formation of wrinkles . 4- Then cut the excess material with blade before setting the material . 5- Then the material should be held in position until complete polymerization. 6- the excess dough material is used to handle fabrication.

26. 7- The handle : 3–4 mm thick, 8 mm in length , 8 mm in height . should be inclined at an angle of 45degrees . should not interfere with the lip movements of the patients. The handle for the lower tray should be straight . Stabilizing handles one on either side are positioned posteriorly . 8- The borders of the tray should be smoothened with tungsten carbide bur followed by using sandpaper.

27. Stabilizing handles

28. 2-Sprinkle on method this technique is not widely used ?! there is no control of uniform thickness of resin impression tray. 1- the polymer powder and the liquid monomer are added in incremental layers.

29. 2- A small quantity of powder is sprinkled on a particular area over the cast and liquid is sprinkled over the powder . 3- Sprinkling drops of the liquid polymerizes the powder. 4- This is continued till the entire ridge and the associated landmarks are covered.

30. Fabrication of shellac custom tray Armamentarium: Shellac baseplate: Maxillary Mandibular • Master cast • Bunsen burner • Curved scissors • Wax spatula • Chip blower • Sandpaper • Marker pen

31. 2- Fabrication of shellac custom tray: the maxillary tray 1- An upper base plate ( D shaped) Is softened by passing both sides Through the flame of a Bunsen Burner. 2- it is then centered over the cast and middle portion is closely adapted to the surface of the cast & allowed to harden.

32. 3- Borders are rolled. 4- section by section the base plate is softened and readapted to the cast following the drawing outline. 5- excess material is trimmed using scissors ,the edges are smoothened using a file. 6- a handle can be made by softening a piece of the same material.

33. the mandibular tray 1- made in the same manner as maxillary tray . 2- a lower base plate ( horse shoe shape) .

34. The difference between shellac & acrylic resin special tray: Shellac plate Self cure acrylic resin 1- low strength. 2- easily distorted by temp.. 3- improper adaptation to the cast. 1- higher strength. 2- not distorted by temp. 3- good adaptation. 4- easily trimmed. 5- light in weight. 6- easily constructed .

35. Thank you