Overlay Denture 3

Dr. Mahmoud Ramadan

Rem. Prosthodontics 502

I

Dr. Mahmoud Ramadan

Remote Over-denture -:Metal base Over­denture → -:Advantages * .( Strong ( i.e. less susceptible to breakage -1 .( More rigid ( i.e. resist the dimensional changes of the denture base -2 .Supporting tissues responds more favorable to the metal base -3 .(It is excellent in jaw relation recording ( i.e. highly stabilized& highly supported -4

-:Disadvantages * .High cost& ↑ time -1 .Relining gives more technical problems -2 .Occupy a space → so, interfere with positioning of artificial teeth -3 .Give poor esthetic effects -4

-:Indications * .Pt. who respond favorably to an interim Overdenture for 8-12 month -1 .Pt. who have the motivation -2 .Pt. who have proper oral hygiene -3 .Pt. who break resien interim Overdentures repeatedly -4

-:Contraindications * .Poor oral hygiene -1 .Lack of motivation -2

-:Abutment coping ♥ -:Advantages → .Caries protection for abutment teeth -1 .Reinforce the endodontically treated teeth -2 .Preserve abutments contours -3 .Produce specific abutment contours& obtain excellent psychological results -4

-:Disadvantages → .time& ↑ cost of treatment ↑ -1 .Irritate the gingival tissue -2 .Marginal caries can occur -3

-:Preparation of the abutment teeth ♥ Incisal or occlusal surface of the coping for metal base Overdenture is convex → → in order to provide rounded contact. → Periodontal, Endodontic, Restorative& Surgical procedures are completed before .teeth prepared for coping

II

Dr. Mahmoud Ramadan -:Sufficient tooth structure is removed 2 or 3mm above the gingival margin for → .A favorable C/R ratio -1 .Placement of artificial tooth similar in size& shape to natural one -2

-:The basic principals in Full crown preparation → a- Occluso-gingival reduction of clinical crown to provide advantage of periodontal .support b- Reduction of the axial surfaces to provide sufficient space for esthetic placement .of denture teeth of proper size& contour .A dowel 5:7mm in root canal is used to achieve the desired retention → Parallel tapered groove can be place in buccal or lingual surface of the canal → preparation to counter rotational forces& to identify the buccal side from the .lingual side during cementation Pins may used for retention instead of a post. ( 2 or 3 pins 4 -5mm long are → .( adequate

-:Making abutment impression ♥ .Full arch impression is made by alginate or rubber base impression → .Impression material is injected carefully around the post preparation → .After setting, the impression is removed& examined → Abutment is treated with fluoride containing solution to inhibit caries & canal → .opening sealed with Gutta-percha It is preferable to cement coping within few days& the interim prosthesis used → .during this period .Impression is poured& die obtained →

-:Wax pattern ♥ Contour should be hemispheric with convex upward& smoothly rounded axial → .surfaces .All abutments copings should be 2:4mm above gingival margin → .Pattern then are sprued, invested, burned out& casted in type III gold →

-:Adaptation of interim Overdenture ♥ By removing resien from coping indentation to permit the denture to seated over → .the coping without interference Acrylic resien is added to the indentation& adapted to coping contour & → .finished .It can be used until pt.'s new denture is completed →

-:Make the impression ♥ .Base plate wax is used to create a space for impression material → .Impression compound used to border molding the tray → .Tray is perforated to ↑ retention of the impression material& to minimize voids →

III

Dr. Mahmoud Ramadan .Then, impression should be poured soon as possible →

-:Design consideration for the denture base Metal base shouldn't extent into pronounced tissue undercut. Because, this → .would interfere with seating the base on master cast Posterior tilt minimize the presence of anterior undercut& facilitate extension of → .the base to this area

-:Mandibular metal base design consideration ♥ -:Extension of metal base (1 .The metal base should extend sufficiently to allow it for jaw relation recording → Displaceable residual ridge tissue& undercut areas may required modifications → .in base extension The base should extend over the ridge portion of the cast& the coping far enough → .to approximate the area covered by the attached gingiva The borders of the metal base should be short enough& completed with resien to → .permit adjustments

-:Relief for copings (2 The relief area should extend approximately 2/3 of the distance up the abutment → and taper in thickness from about 0.5mm at the gingival margin to 0.0mm at the .Incisal extent of the relief

IV