complete denture - laboratory fabrication

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Complete Denture : 

Complete Denture A dental prosthesis that replaces all of the natural dentition and associated structures of maxilla and mandible. It may be supported by mucosa or sometimes by dental implants.

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Esthetic. Improve mastication. Improve speech. Function without interferences. Preservation of oral structures. Maintenance of health & comfort. Objectives of complete denture

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Types of impression

Primary impression : 

Primary impression Negative replica of the oral tissues Done for the purpose of diagnosis or construction of tray

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Stiff to prevent distortion. Workable thickness must be 4mm. Altered in areas hindering the ridge. Borders - 2mm short of vestibule. HOW A TRAY SHOULD BE?

Tray selection : 

Tray selection

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Perforated tray Non- perforated tray. Impression materials

Conditioning the impression : 

Conditioning the impression Sprinkle dental stone on impression Disinfection - immersing in disinfectants for 10 mins 2% glutaraldehyde bleach iodophor trimming excess with BP blade

Primary cast : 

Primary cast Pour the plaster in the impression in 3 steps. Done within 15min after impression making. Base should have 10mm thickness. Pouring should be done from distal end. Trimming

Requirement of cast : 

Requirement of cast Free of voids. Record the details accurately . Extend 3 to 4mm beyond retromolar pad . Moisture free.

Special tray : 

Special tray A custom made device prepared for the particular patient which is used to carry , confine and control an impression material while making an impression.

Why is it needed? : 

Why is it needed? Overview Of Border Moulding . To Support Green Stick Compound. To Make Out Final Impression . To Provide Even Thickness Of The Impression Material.

Requirements : 

Requirements Well adapted to the primary cast . 2mm thick in the palate area and lingual flange for rigidity. 2mm relief near the sulcus. Free of voids & projections in the tissue surface.

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shellac Cold cure resin polystyrene Materials for custom tray fabrication

Polystyrene Trays : 

Polystyrene Trays

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Soak in water Draw the outline on the cast. Block out the undercuts using wax. Place the wax spacer on the cast. Conditioning the primary cast

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record tissues in a state of anatomical rest. Stability during impression making. Relief the non stress bearing areas . 2mm thick. modelling wax , non asbestos & casting liner. Spacer: Why is a spacer needed?

Fabrication of custom tray (cold cure resin) : 

Fabrication of custom tray (cold cure resin) Sets by chemical reaction autopolymerising Irreversible Two techniques

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L/P ratio – 1 : 3 After mixing monomer & polymer undergoes six stages - wet sandy - early stingy - late stingy - dough - rubbery - stiff Dough technique

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Manipulate in dough stage. Knead to achieve a homogenous mix. Adapt the rolled sheet from centre to periphery. Remove excess with BP blade. After cutting hold in position to prevent shrinkage & warpage during polymerisation. Trimming . Monomer is sprinkled on the groove for chemical bonding .

Handle : 

Handle Place anteriorly. 3mm thick 8mm long 8mm high. Should be parallel to the long axis of the teeth. Soak the tray in water to prevent warpage

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Negative likeness made for the purpose of fabricating a prosthesis. It should have the finer details of denture bearing area at rest . border moulding / peripheral tracing make wash out impression postdamming Secondary impression Steps:

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Techniques in making secondary impression

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The shaping of an impression material by manipulation or action of tissues adjacent to the borders of impression : simultaneous border moulding incremental border moulding Techniques involved Border moulding/ peripheral tracing

Tray preparation before imp. making : 

Tray preparation before imp. making Wax spacer should be removed. Remove 0.5 – 1mm of tracing material but not in post. palatal seal. Flanges and the border should be 2.5 to 3mm thick. Drill holes in tray to prevent tissue displacement during imp.making.

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Tracing material enhances post palatal seal. Serves as guide for positioning the tray . Prevents aspiration of imp. Material. Why is post palatal seal preserved?

Materials for secondary imp making : 

Materials for secondary imp making

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Imp. must be free of voids which is rectified by wax. Disinfect with iodophor or 2% glutaraldehyde for 10 mins. Requirements

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Prevents the width and height of the sulcus Mainly preserves mucobuccal and mucolingual borders. Materials used beading utility wax boxing plaster with pumice , paddle boxing and caulking compound . Beading & boxing

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Replica of the tooth structures , residual ridge areas and other parts of the dental arch or facial structures used to fabricate a dental restoration or prosthesis. Master cast

Record base : 

Record base Base of denture . Support wax occlusal rims. Requirements : Well adapted to the final cast . Dimensionally stable. Retentive . 1mm thick on the crest and facial slope of the ridge . 2mm thick in the palatal and lingual flange. Smooth and rounded borders.

Record base

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ZnOE. Elastomeric impression materials . Soft and hard curing resins. Stabilising materials

Occlusal rims : 

Occlusal rims Occluding surfaces built on temporary or permanent denture bases for the purpose of making maxillo-mandibular relation records and arranging teeth. Primarily serves as gingiva Done mainly to arrange teeth

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Rolled wax technique Pre-formed occlusal rim Metal occlusal rim former Occlusal rim techniques

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22mm high from the depth of the sulcus. Ant region should be 8mm away from incisive papilla . 4 – 6 mm wide in ant region. Occlusal table should be 18mm high from the depth of sulcus. Occlusal table should be 8 – 12 mm wide posterior. Occlusal table should be 10 – 12 mm above the crest of alveolar ridge anteriorly. Maxillary occlusal rim

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Thermoplastic material Adapt from centre to periphery using Bunsen flame. Overheat may lead to leaching. Adapt by applying pressure with a wet cotton swab . Borders are adapted upto sulcus using a blunt spatula . shellac Adaptation:

Mandibular occlusal rim : 

Mandibular occlusal rim 6 -8mm high from the crest of the ridge anteriorly 18mm high from depth of the sulcus in the canine eminence region 3 – 6mm high from the crest of the ridge posteriorly The occlusal plate should extend to 2/3rd ht of the retromolar pad posteriorly Width anteriorly 4 – 6mm posteriorly 8 – 12mm

Centric occlusion: : 

Centric occlusion: Term used to describe the position of the lower jaw when the teeth are fully occluded together. Centric relation: It is the mandibular jaw relation in which the head of the condyle is situated as far superior and posterior as it can.

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A Device Used To Record The Positional Relations Of The Maxillary Arch To The Tempromandibular Joints And To Orient Dental Casts In This Same Relationship To The Opening Axis Of The Articulator . Facebow

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Articulator A device that may be adjusted to permit movement of the casts into various recorded eccentric relationships

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The procedure of attaching the maxillary and mandibular casts to the articulator in the recorded jaw relations. Zeroing the articulator. Mounting the maxillary cast. Mounting the mandibular cast. Articulation Mounting procedure:

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MOUNTING Bennett angle –30 Incisal pin position should be at zero point to the incisal table. Maxillary cast – face bow transfer records. Mandibular cast – centric relation records.

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Maxilla: Teeth setting

Mandible: : 


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A malocclusion of the teeth in which the front upper incisor and canine teeth project over the lower. vertical overlap. overbite

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Increased projection of the upper teeth in front of the lower teeth, usually measured parallel to the occlusal plane. Horizontal overlap. overjet

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The contouring of a pattern in wax generally to shaping in wax of the contours of a trial denture. Wax Up

Requirements : 

Requirements Aesthetics. Functions of denture. Prior to try -in for better treatment outcome . Retentive quality. Imitate the tissues around the natural teeth. Proper thickness.

procedure : 

procedure A softened rolled baseplate wax is kneaded and adapted over the cervical area of the teeth. Wax width-6mm, 5mm long Depression should be created between the central incisor and canine.

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. Should give convex contour to the dental flange. Concave flange contour to molar regions. Prominent bucco-gingival margins.

Festooning : : 

Festooning : By creating depressions interdentally. Wax should be carved around the neck of the tooth with wax spatula. Anteriors- 60degree. Posteriors – 45 degree. Thin down near neck of the teeth for free gingiva. Carving :

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Stippling is produced interdentally with a tooth brush or bristle brush in the region of attached gingiva. Effective in regions of interproximal areas.

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Polish by flaming and wiping with cotton. Polish with damp nylon stocking in rough areas. Normal thickness – 2mm -2.5mm. Polishing

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Involves Replacing The Base Of Waxed Portions With Final Denture Materials Denture processing

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Separation of cast Flasking Dewaxing Curing Denture processing Packing

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Sealing: The Denture Is Sealed To The Cast At Its Borders With Molten Wax. Cast Separation. Cast Preparation

Why sealing is done ? : 

Why sealing is done ? It Helps To Maintain Position Of The Denture. Mainly Prevents Plaster From Getting Under The Denture.

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Process by which trial denture is surrounded by stone / plaster in a metal flask . It basically creates a mould for acrylic denture. Flasking / Investing

Flasking Techniques : 

Flasking Techniques Two Pour Three Pour Four Pour Ideal Material For Investing - Stone

Three Pour Technique : 

Three Pour Technique Flask- Hanau flask . Soak the cast in slurry water. Checking the fit . Excess height is trimmed off. Lubricate using petroleum jelly . Reduces the possibility of distortion and fracture. Deflasking is easier. Advantage:

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Separating media is applied at base of sides. Stone filled in the lowest portion. Allowed to set for 20mins. Apply separating media over 1st pour . Middle portion of flask is assembled and pour the 2nd mix till the occlusal surfaces of teeth and allow to set for 20mins. Excess stone is removed to expose cusp tips . First pour: Second pour:

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Separating Media Is Applied Again. Stone Mix Is Poured Filling The Remainder Of Flask. Allow To Set For 20mins. Third pour:

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Similar To 3 Pour Technique. A Stone Core Is Built Over The Wax Surface Thickness – 2-4mm Height - 2-3mm Below Occlusal Surfaces. Four Pour Technique

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First Pour Cast Is Flasked In Lower Half. Second Pour Rest Of The Flask Is Filled. Difficult To Deflask Risk Of Fracture Risk Of Distortion Two Pour Technique Disadvantages:

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Eliminates the wax and temporary denture base for mould space. Place in boiling water for 5mins. Excess time in boiling water causes wax liquify and soak in stone. Opened flask is flushed with boiling water to remove remaining wax. Dewaxing

Separating Media : 

Separating Media Separating Media Is Applied To The Dewaxed Mold Space Prior To Packing The Acrylic Resin Objectives: Prevent Water From Mold Entering Into Resin Which May Affect The Rate Of Polymerisation. Prevent Monomer Penetrating Into Mold Material , causing Plaster To Adhere To The Resin And Producing A Rough Surface.

Types of separating medias : 

Types of separating medias Tin foil Cellulose lacquers Solution of alginated compounds Calcium oleate Soft soaps Sodium silicate Starches Most commonly used separating medium is sodium alginate solution which is also called as ‘cold mould seal’.

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Apply separating media on to the stone surface excluding the teeth. Mixed acrylic dough is formed into a roll and adapt into mould space. A plastic separating sheet is placed over the dough and 2 halves are closed with pressure. Packing

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The Flask Is Separated And Excess Is Trimmed Off. In Final Closure Remove The Separating Sheet. Flask Is Transferred To Clamp And Resin Is Allowed To Expand. Flasks Are Secured In Clamp And Placed Aside For 30mins.

WHY? : 

WHY? Permits equilization of pressure. Allows time for uniform dispersion of monomer. Helps in better bonding of tooth with base material.

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Polymerisation. It Is Defined As Forming Of A Compound By Joining Together Of Molecules Of Small Mol.Wt Into A Compound Of Large Mol.Wt. Curing

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Equipment Spl Electrical Curing Chambers : 

Equipment Spl Electrical Curing Chambers Short Curing Cycle Flask Is Kept In Water At Room Temp. Is Raised For 74 Degree And Maintain For 2hrs. Boil For 1hr.

Long Curing Cycle : 

Long Curing Cycle Slow. Cure At Low Temperature For Long Time For Thick Dentures. Less Prone To Porosity. Temp – 74 Degree. Time – 8hrs. No Need To Boil.

Less Risk Of Porosity. Less Residual Monomer. Indicated For Thick Acrylic Appliances. Advantages

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Slow Cooling Bench Cooling. Fast Cooling Bench Cooling For 30mins And Placing It Under Running Tap Water For 30mins. Cooling

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Removal of denture from flask using a wedge instrument. Hanau flask is stabilised in a hydraulic press. DEFLASKING


TRIMMING Excess should be trimmed off to reproduce the accurate details. Abrasives Used for polishing and finishing irregular surfaces.

Lathes Used For Trimming : 

Lathes Used For Trimming

Types: : 

Types: Pumice: Siliceous Material Of Volcanic Origin. Used As Both Abrasive/Polishing Agent Depending On Particular Size.

Carbides: : 

Carbides: Silicon carbide , boron carbide - abrading agents. si/boron + C carbides of the high temp respective forms.

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The silicon carbide is sintered / pressed with binder into grinding wheels/ disks. Eg: most of the stone burs are made of SiC.

Trimming: : 

Trimming: For trimming borders: lathe mounted arbor band. laboratory sized carbide burs. For deeper frenum notches: fissure bur mounted on lathe. To remove stone in betn. Teeth/ to remove acrylic nodules from denture: pointed chisel/ fissure bur

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To finish lingual border of denture: small sized carbide bur. To reduce thickness of palate: large egg shaped bur.

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Coarse abrasives

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FINE abrasives

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A slurry of fine flour of pumice with water is made. The rag wheel is wetted using the slurry and polished at low speed. In case of less accessible areas a brush/ prophy cup with slurry is used for polishing. High shine is produced using no.341 TiGleam . PUMICING PROCEDURES

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Finally the denture is brushed with green soap to remove all traces of polishing material. Rinse Storage - water.

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tHANK yoU B Y Radeep. Reetha. On udhaya. Eriyasamy. radeepa. 2nd yr BDS., TNGDC, chennai. P

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Questions? ?  ?  ?   ? ?    Questions? Questions? Questions?  

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