CD2NDMONTHQ1.PDF

MASTER CAST/ WORKING CAST RETRIEVING OF CASTS -replica of the denture bearing areas and other -after the cast has set, place the tray with cast structures of the oral cavity needed to fabricate in hot water to soften the low fusing compound a dental prosthesis...

MASTER CAST/ WORKING CAST RETRIEVING OF CASTS -replica of the denture bearing areas and other -after the cast has set, place the tray with cast structures of the oral cavity needed to fabricate in hot water to soften the low fusing compound a dental prosthesis and carefully separate the cast from the impression REFRACTORY CAST TRIMMING THE MASTER CAST Treatment MASTER CASTS FOR COMPLETE DENTURES 1. Boxing 2. Basing -it is on these cast that dentures are made Requirements Equal thickness No U-shaped cast for the lower 1. TRIMMING BEADING -procedure of reducing the size altering the shape of the cast and retaining important structures behind LAND AREA Requirements -the portion of a dental cast that extend beyond -smooth and flat base the impressions replica surface laterally -absence of nodules -absence of undercuts BOXING AN IMPRESSION -the enclosure (box) of an impression to produce the desired size and form of the base 2. OUTLINE OF BASE FOR TRIMMED of the cast and to preserved desired details CASTS -follow the contour of the ridges, with rounded angles ADVANTAGES OF BEADING AND BOXING COMPLETED MASTER CAST -superior hardness of cast surface LAND – 2-3 mm - provides land area DEPTH OF VESTIBULE – 2-3 mm -preserves border of the impression BASE – 15-17 mm thick Minimizes trimming TRIMMED MODEL POURING OF CASTS -sides of the cast should be vertical an -once beading and boxing is done pour cast perpendicular to the base. with dental stone ( 100 gm of stone to 28-3] ml of water) and allow it to set about an hour -they should not inclined inward or outward -tongue space on the mandibular casts should 3. The anterior of the PPS is drawn in the cast to be trimmed flat coincide displaceable (glandular) soft tissue of the palate -it is approximately 3-6 mm anterior to the POST DAMMING OF THE MASTER CAST vibrating line -beading along the posterior palatal seal area 4.The deepest extent of the PPS should be on *do grooving on the cast along the PPS area the posterior border which connects from the hamular notch -a cut of 5mm in depth passing the vibrating line -done using a discoid end of the veje carver, must extend 3mm lateral to the crest of the FUNCTIONS hamular notch 1. To provide tissue displacement 5.The anterior border is shaped For peripheral seal area -going anteriorly the depth decreases from 1.5 2. To compensate for nah acrylic resin to 0 dimensional change that takes place after processing 3. To maintain the constant intimacy of RECORD BASE AND OCCLUSION RIM the contact between the posterior border of the maxillary denture and soft BASEPLATE palate during function -an interim material device used in making maxilla mandibular relation records and arrangement of teeth PROCEDURE -it is where the occlusion is placed 1.Determine the type of soft palate DENTURE BASE a.Form A -the part of the denture that rest of the denture -narrow soft palate bearing areas -wider and deeper post damming OCCLUSION RIM/RECORD RIM b. Form B -occlusal surfaces fabricated on denture bases -average soft palate for the purpose of making maxillomandibular relationship records and where the teeth are -narrow butterfly shaped post dam arranged c. Form C -made of wax - broad and deep soft palate form 2. The posterior border of the PPS is drawn in the cast -best guide is by placing it 1-2 mm anterior to the fovea palatini REQUIREMENTS OF RECORD BASES 3.Light cured resin 1. It should be readily adapted to the -they are copolymers with silica fibers required shaped and contour with -exposed to high intensity light 400-50] mm for minimum time, expense and technical 10 mins skills 2. It must relatively rigid and strong in Advantage: does not contain ,monomer no relatively thin section time element, can be moulded to desired 3. It does not exhibit flow at mouth shape temperature Disadvantage: slightly slow strength compared 4. It does not warp or distort during the with autopolymerizing resin procedures of denture fabrication 5. It must exhibit a color close to that of the natural gingiva 4.Wax -extra hard baseplate is used/high heat wax MATERIALS FOR RECORD BASES Advantages: easier to use during setting of 1. Shellac base plate teeth with restricted inter arch distance, setting 2. Auto polymerizing resin is easier if you don’t have space 3. Light cures resin (vlc) Disadvantage: brittle, lacks rigidity and 4. Wax stability, can be easily distorted 5. Vacuum formed base 6. Microwave activated resin 7. Processes acrylic resin 5.Processed acrylic resin 8. Cast alloys -make use of heat cured resin in slow curing Advantage: permanent denture base, stable ADAPTATION OF RECORD BASES Disadvantage: might get distorted during 1.Shellac base plate double processing when not properly handled -available as preformed shape for max and man arches 6.Cast Alloys Advantage: inexpensive, easily and quickly adapted -can be made of of gold, chrome cobalt, nickel chrome Disadvantage: tends to warp (do nkt expose direct to sunlight) brittle, when overheated it Advantage: rigid, accurate and dimensionally adheres on the cast stable, thinner with thermal productivity Disadvantage: more expensive, time consuming, adds more weight 2.Auto polymerizing resin -polymer and monomer pink resin with fibers Advantage: easy to manipulate Disadvantage: high polymerization shrinkage USES OF OCCLUSAL RIMS a.orientation relation-facebow -wax forms are used to establish b.vertical relation 1. Level of occlusal plane c.horizontal relation 2. Arch form 3. Different jaw relations CONSTRUCTION 1. Adapt shellac base plate same as doing the individual tray, but now follow the outline of the prospected baseplate 2. Soften wax, roll Maxillary: the roled wax is place slightly buccal to the ridge Mandibular: rolled wax is placed directly on the crest of the ridge 1.LEVEL OF OCCLUSAL PLANE FRONTAL VIEW: incisal plane parallel to the interpupillary line 3. Adapt the wax to the baseplate and countour. SAGITTAL VIEW: occlusal plane parallel to the ala-tragus line Retromolar pad- determines the height of 4. Maxillary and mandibular occlusion rim occlusal plane must occlude and are even in contact with each other -divide into 3 equal parts -2/3 will be level of the occlusal plane 2.ARCH FORM -related to the activity of the lips, cheeks, and tongue and harmonious with the various forces acting on it. -arch should mimic the facial profile -placing in the neutral zone- it must simulate the the dental arch, as if the teeth are there 3.THE DIFFERENT JAW RELATIONS