DEN203_20F_W3_Impression and Boxing.pdf

DEN203 Prosthetic Dentistry II Lecturer: Dr. Rana Turunç Oğuzman & Dr. Demet Ayvalıoğlu E-posta: [email protected] Impression and Boxing Altınbaş Üniversitesi Rana Turunç Oğuzman [email protected] DEN203 Protetik Diş Tedavisi 2 To remember… • Mark the anticipated final e...

DEN203 Prosthetic Dentistry II Lecturer: Dr. Rana Turunç Oğuzman & Dr. Demet Ayvalıoğlu E-posta: [email protected] Impression and Boxing Altınbaş Üniversitesi Rana Turunç Oğuzman [email protected] DEN203 Protetik Diş Tedavisi 2 To remember… • Mark the anticipated final extensions of the denture with red pencil on the cast. To remember… • Mark the tray extension with black pencil about 2 mm shorter than the first pencil line except in posterior palatal seal area To remember… • Block out under cuts with modelling wax • To avoid breakage of the cast or the tray Undercut • The contour of a cross sectional portion of a residual ridge or dental arch that prevents the insertion of a dental prosthesis. To remember… To remember… • The spacer provides room for the impression material . • It also minimizes the pressure that could distort the mucosa To remember… • Apply seperating media on the cast so that acrylic resin does not stick to the cast To remember… • Seperating Media; Sodium Alginate + calcium sulfate = insoluble calcium alginate To remember… To remember… • Adapt tray material in dough stage Handle • Supports the lip while making impression • Tray handles are particularly helpful while loading, placing and orienting custom trays in the mouth. Finger Rests • Finger rests help in holding the tray in position while making the final impression Trim the tray Trim the tray To remember… • Tray periphery should be 2- 3 mm thick. The edges should be rounded. The rest of the tray should be about 2 mm in thickness. Border Molding • Check the borders Low fusing Compound Border Molding • Shaping the border areas with an impression material by functional or manual manipulation of the soft tissue adjacent to the borders to duplicate the contour and size of the vestibule. Materials Used For Border Molding • Low fusing compound • Putty consistency of elastomeric impression materials Border Molding - Maxillary Border Molding - Mandibular Final Impression • The impression that represents the completion of the registration of the surface or object. • Also called master impression Final Impression Materials Used For Final Impression • Zinc Oxide Eugenol Impression Paste • Elastomeric Impression Materials Definitive Cast • A replica of the residual ridge areas, and/or other parts of the dental arch used to fabricate a prosthesis; • Also called final cast or master cast Materials used for making final casts: • Alpha hemihydrate (dental Stone) Methods of Pouring Casts 1. Inversion Method ( for preliminary casts) 2. Beading and boxing method ( for master casts) - Wax Boxing Method - Plaster of paris and pumice method Wax boxing Method Maxillary Impression 1) Apply a layer of sticky wax around the the impression 3 mm below the periphery as shown. Wax boxing Method Maxillary Impression 2) Apply and seal rods of beading wax to the sticky wax on the impression to form the land. Wax boxing Method Maxillary Impression 3) Wrap a sheet of red boxing wax around the beading wax to form a container. All joints must be sealed with hot wax to prevent stone from leaking through. Wax boxing Method Maxillary Impression Land Area Wax boxing Method Maxillary Impression The portion of a dental cast that extends beyond the impression’s replica surface laterally Plaster of Paris and Pumice Method Maxillary Impression 1) Draw a line around the impression 3 mm up from the periphery. 2) Set impression in a 1:1 mixture of plaster and pumice. 3) Push impression halfway into the mix. 4) Push the mix up around the impression with a spatula to create a land at the level of the line drawn on the impression. 5) When the mix is set, trim on the model trimmer to create a 4-6 mm land. Plaster of Paris and Pumice Method Maxillary Impression 6) Wrap the impression in sheet wax and seal it to the plaster pumice boxing with hot wax 7) Brush a light layer of vaseline onto the plaster land area so that the stone of the cast does not stick to the land 8) The container made from the wax sheet must be at least one half inch above the highest point of the impression to create an adequate base to the cast. Maxillary Impression, Pouring the Cast Prepare a dense mix of yellow stone using your vacuum mixer and vibrate the stone into the boxed impression. Be careful to avoid entrapment of air bubbles. Wax boxing Method Mandibular Impression • Apply a layer of rubber base adhesive or hot sticky wax to the impression as shown. • This layer should about 3 mm above the height of the border of the impression. Wax boxing Method Mandibular Impression •Apply a strip of red beading wax to the sticky wax layer to form the land of the cast. •Close the lingual tongue area of the impression with a sheet of wax or with pumice and plaster. Wax boxing Method Mandibular Impression Plaster of Paris and Pumice Method Mandibular Impression The same result can be achieved by boxing the entire impression with a mixture of plaster and pumice (to form the land area) and boxing wax to create the enclosure. If you use this method be sure to coat the plaster pumice mixture with vaseline before you pour stone into impression so that cast will separate from this mixture. Mandibular Impression- Pouring the Cast • Before you pour the cast make sure the boxing is sufficient to permit the fabrication of a cast at least 10 mm thick. •Mix the yellow stone •Carefully pour the stone into the impression. Start on the buccal of one side and progress to other side. Vibrate the impression during pouring to avoid air bubbles •Wait 1 hour for the stone to set • Immerse the cast-impression into hot water and wait for 5 minutes to soften the compound border molding before separating the cast from the impression. Retrieving the Cast After heating the compound in a water bath, carefully separate the cast from the impression Trimming the Cast • With a model trimmer flatten the base, so that the base is parallel to the ridge. • Trim the sides of the cast, so that there is an even 4-6 mm of land around the cast. • Trim the land with a burr or sharp knife and reduce so that the depth of the peripheral roll is 2-3 mm throughout. Trimming the Cast Trim master casts. The base should not be thicker than 15-20 mm. If the base is too thick the cast will not fit within the confines of the denture flask. The land of the cast must be at the same level as the edge of the lower member of the flask. Completed Master Cast Land (4-6mm thick) Depth of peripheral roll (2-3 mm) Base (15-20 mm thick) Trimming the Master Cast Thickness of the base for this cast was insufficient and eventually it fractured necessitating remaking of the impression Master Casts These casts have been properly trimmed. Place rounded notches (arrows) on the bottom of the master cast. These notches will later be used to remount the processed denture back onto the articulator. Videos 1. Border molding of lower jaw and znoe final impression https://youtu.be/KpmyZj3_fbY 2. Boxing ▪ a) Wax boxing Maxillary https://youtu.be/Yq9bAEG73W4 Mandibular https://youtu.be/Tq-x5M61Cz8 b) Plaster pumice technique https://youtu.be/G37zfglUf80 3. Fabricating master cast for full denture • pouring the dental stone: https://youtu.be/k2wPI7lpTJg • separating impression tray from stone and trimming: https://youtu.be/F_OV14CHxIg