wax pattern M.Hosny.pdf

2/19/2019 M.Hosny Presented by Dr. Mohammed Hosny Associate Professor of Fixed Prosthodontics Collage of Dentistry Taibah University 2/19/2019 M.Hosny Steps 2/19/2019 M.Hosny Wax pattern is a wax form that is a positive replica of an object to be fabricated 2/19/2019 M.Hosny Uses ...

2/19/2019 M.Hosny Presented by Dr. Mohammed Hosny Associate Professor of Fixed Prosthodontics Collage of Dentistry Taibah University 2/19/2019 M.Hosny Steps 2/19/2019 M.Hosny Wax pattern is a wax form that is a positive replica of an object to be fabricated 2/19/2019 M.Hosny Uses Fabrication of : •Full metal inlays and onlays . •Partial coverage restorations. •Custom made post and core. •Full metal fixed prosthodontics. •Substructure for ceramo- metallic restorations. •Ceramics. •Precision attachments. •Metallic framework for removable partial denture. •Complete denture. 2/19/2019 M.Hosny b. MODIFIER Waxes c. COLORANT 2/19/2019 M.Hosny Inlay casting wax Boxing wax Occlusal registration wax 2/19/2019 M.Hosny Sprue wax Generally: •Non toxic •Environmentally neutral In fixed prosthodontics work : •Conveniently manipulated and precisely shaped by heating. •Can be completely eliminated from the mold with burning out after investing. 2/19/2019 M.Hosny 1- Be of some color that will contrast easily from the stone die. 2- Flows readily when heated without chipping, flaking or loosing smoothness. 3- When cooled, it must be rigid. 4- Accepts addition and capable of being carved without chipping or distortion. 2/19/2019 M.Hosny 5- Has a minimum rate of stress relaxation after carving and before investing to prevent any distortion. 6- Preserves the fine and sharp details till investing without distortion. 7- Burnout without leaving any residual ashes that might contaminate the produced casting. 2/19/2019 M.Hosny ADA classification Type I 2/19/2019 M.Hosny Type II  Type I: Used for making intra-oral wax pattern (direct technique) it must not follow at mouth temperature.  Type II: Used for the indirect fabrication of casting. It must not flow at room temperature. 2/19/2019 M.Hosny According to use Dipping wax 2/19/2019 M.Hosny Modeling wax •Electrically heated , heated with Bunsen flame. •Opaque ,transparent •Special purpose wax 2/19/2019 M.Hosny Occlusal anatomy wax 2/19/2019 M.Hosny Pontic wax 2/19/2019 M.Hosny According to site 2/19/2019 M.Hosny Direct method 2/19/2019 Indirect method M.Hosny Indirect -Direct method 1- Direct Technique: ❑ Pattern is constructed inside patient’s mouth Indicated for inlays and casted posts. ❑ Medium or hard wax is usually used for this method 2/19/2019 M.Hosny 2- Indirect Technique: ➢Pattern is constructed outside the patient’s mouth ➢Most commonly used method due to its accessibility, visibility & time saving for both dentist and patient. 3- Indirect-Direct Technique: Pattern is constructed indirectly and fine adjustments are carried out intra-orally before its casting. 2/19/2019 M.Hosny 2/19/2019 M.Hosny Dipping method Molten press method 2/19/2019 M.Hosny Addition method Injection method Used for researches purposes only 1- Dipping method: by dipping the die in a molten wax using dipping pot. 2. Addition method: by melting the wax and dropping it on the die by a heated carver, then carved by sharp carver→ strain collected from multiple additions → after cooling → released → distortion 2/19/2019 M.Hosny 3. Molten press method: by adding molten wax and pressing it by the fingers at each application → then electric wax instrument used for wax addition ❖ overcomes stress relaxation of wax; most accurate technique. 4. Injection technique: by injection of molten wax through metallic syringe into mold. Used in researches only. 5- CAD/CAM system 2/19/2019 M.Hosny 2/19/2019 M.Hosny Electric heating Bunsen flame 2/19/2019 M.Hosny According to mode of usage Manual 2/19/2019 M.Hosny Electric Hand instrument according to use 1&2 for PKTs instrument Wax addition No. 3 for Wax burnishing No. 4 for Wax carving Wax spatula No. 5 for Wax carving 2/19/2019 M.Hosny Other instrument:1- Separating liquid 2- Soft wax brush 3- Occlusal indicator powder. 4-Wax gauge (caliper) 5- Die lubricant 2/19/2019 M.Hosny 2/19/2019 M.Hosny 2/19/2019 M.Hosny Preparation of die prior to wax pattern construction 1. Trim away free gingiva to define the margin. 2. Ditching; acts as a guide during wax pattern construction. It is a circumferential groove below finish line to 0.3 mm depth. 3. Color FL with red color. 4. Die spacer; space 20-40micron. 1mm band at the margin is left unpainted. 5. Die is lubricated by water-soluble lubricant to reduce surface tension and allow free flow of wax. 2/19/2019 M.Hosny 2/19/2019 M.Hosny 2/19/2019 M.Hosny Well adapted (correct) Poor adapted (incorrect) 2/19/2019 M.Hosny 2/19/2019 M.Hosny 2/19/2019 M.Hosny 2/19/2019 M.Hosny 2/19/2019 M.Hosny  Flat or slightly concave; not convex.  Over contouring→ gingival inflammation.  Under contouring→ make flossing ineffective. 2/19/2019 M.Hosny Contact areas  Large → plaque control difficult and can lead to periodontal disease.  Very small → contacts unstable and cause teeth drifting.  Deficient → lead to food impaction. 2/19/2019 M.Hosny 2/19/2019 M.Hosny ➢ Height of contour buccally and lingually is rarely 1mm wider than at the CEJ. ➢ Height of contour: facial→ cervical 1/3 ➢ Lingual maxillary → cervical 1/3 ➢ Lingual mandibular → middle 1/3 2/19/2019 M.Hosny Emergence profile  Tooth surface gingival to height of contour till the base of gingival sulcus is called emergence profile. It is either flat or slightly concave. 2/19/2019 M.Hosny Occlusal scheme  It is classified by the location of occlusal contact made by the functional cusp on the opposing teeth in centric relation.  Functional cusps; B of mandibular and P of maxillary contact either with occlusal fossae (cusp-fossa) or marginal ridges (cusp-MR) of opposing teeth. • Non functional cusps:  Prevent food from overflowing  Protect buccal mucosa and tongue 2/19/2019 M.Hosny Cusp to fossa  In cusp-fossa scheme, mandibular centric cusps contact further distally into the mesial fossa of the maxillary tooth; they contact only one tooth. * It is recommended in full mouth rehab, yet it is rarely found naturally. Advantages: 1. Prevent food impaction; prevent wedging between teeth. 2. Forces falling nearer to long axes. 3. Improved stability→ from tripod contacts for each centric cusp. 2/19/2019 M.Hosny Cusp-Marginal ridge  In cusp-marginal ridge scheme, the buccal cusps of mandibular premolars and mesiobuccal cusps of mandibular molars contact into the embrasures between maxillary teeth; they contact two teeth. 2/19/2019 M.Hosny Curve of Spee  The functional and non functional cusps of the maxillary posterior teeth become slightly shorter as they progress distally.  The resulting antero-posterior curvature of occlusal plane is called curve of Spee.  It helps to prevent protrusive interferences. 2/19/2019 M.Hosny Curve of Wilson  It is the left-right curvature resulting from the non functional cusps being shorter than the functional cusps.  It prevents the interferences in lateral excursions. 2/19/2019 M.Hosny Margin finishing  Return the pattern to the die.  Margins must be reflowed and refinished immediately prior to investing the wax pattern. This happens over a band 1mm wide.  It is a combination of melting, burnishing and carving Objectives: 1. minimize dissolution of cement. 2. facilitate plaque control. 2/19/2019 M.Hosny Wax Reflow (Margination) Marginal flashes are then carved to the finish line 2/19/2019 M.Hosny Checking wax pattern on the die 2/19/2019 M.Hosny Removal of wax pattern ➢ To remove the wax pattern, the die is held by the fingers of the left hand and the right hand holds the pattern, the die is then pulled from the pattern by bending the fingers of the left hand. 2/19/2019 M.Hosny 2/19/2019 M.Hosny