8 GEN 2022 · Structural Durability :- i. Functional cusp bevel -2 mm* for structural durability ii. Proper oclusal / incisal clearance iii. Incisal edge — 2 mm * iv. labial — 1.5 mm METAL CROWNS  All surface reduction of 0.5 (max-1.0mm)  Sharp line angles are okay METAL-CERAMIC CROWN - 1.5 (max-2MM) PREP (0.5 FOR METAL, 1-1.5 FOR CERAMIC) - FUNCTIONAL CUSP / INCISAL – 2MM REDUCTION - WALLS -6 DEGREE TAPER, NOT MORE THAT 10DEGREE - CHAMFER FINISH LINE - ALL MARGINS PLACED SUPRAGINGIVALLY - Can have sharpline angles ALL CERAMIC CROWN  SAME CONFIGURATIONS 1.5-2mm  At incisal / cuspa – 2mm for any type of preparation  Shoulder finish lines  ALL line angles SHOULD BE ROUNDED, NO SHARP ANGLES  THIS IS TO AVOID PORCELAIN FRACTURE Q. For onlays preparation reduction of functional cusp 1.5 mm. Q. The amount of reduction in all ceramic crown 1 – 1.5 mm. Q. The amount of reduction in PFM crown 1.5 – 2 mm. Q. The incisal reduction for a metal ceramic restoration should be 2 mm. Q. The amount of reduction in metallic crown 0.5 mm. *Minimum thickness of metal — 0.5 mm required, thus gives adequate strength *Bevel all functional cusp — to give thick material at the region and thus resist occlusal forces Maryland / Resin bonded bridge i. Indication a. maxillary lateral incisors * b. poor oral hygiene ii. Advantage a. better hygiene maintainability b. conserve tooth structure. iii. Disadvantage — weak bond — poor retention of resin and metal

8 GEN 2022 · PRINCIPLES OF TOOTH PREPARATION Preservation of the tooth structure - 4 models of preparations 1. THREE QUARTER CROWN i. Occlusal + proximals + lingual ii. Labial is untouched iii. They are retained by grooves on mesial, distal & occlusal surfaces. iv. For all teeth v. Bur used to add retentive groove is – Tapered (/radial) fissure bur* vi. Always made of cast metal. 2. REVERSE / MODIFIED ¾ CROWN  Preserves lingual surface  Commonly for mandibular molars  Damaged buccal surface with intact lingual side  Also useful on lingually tilted molar, coz lare amount of tooth structure may need to be removed, might involve the pulp. So to avoid that. 3. MESIAL / PROXIMAL HALF CROWN vii. Mesially tilted mandibular molars 4. SEVEN BY EIGHT CROWN  For posterior esthetics  On maxillary molars  Mesiobuccal area not prepared or crowned  Mesial 1/3rd of buccal surface — unprepared.  Useful in distal surface caries  More coverage than a ¾ th crown Mesially Tilted crown cases — mandibular molars. b. Orthodontic uprighting (theoretically 1st choice , for exam point of view) c. Use of non-rigid connectors (key and key hole, tenon-mortis etc) d. Mesial half crown e. Telescopic crown (least preferred type) Retention and Resistence a) Degree of taper - 6° tapering b) Best bur — tapered fissure ---------i. Diamond coated ---------ii. Or tungsten coated carbide bur, known as 159L bur TWO PLANE PREPARATION * COMPLICATIONS OF 1 PLANE A. Incisal only — food lodgement i. Poor oral hygiene ii. Gingival health compromised B. Gingival only — opaqueness on incisal edge Q. The ideal post drill for most posterior teeth is: peso drill size 2-3. Q. Instrument used for wax grooving for a die in FPD: * Instrument we use to make a groove in the wax is: PKT no3.

8 GEN 2022 · Marginal Integrity – FINISH LINES a) Finish line — the junction between prepared and unprepared position — should be at contra bevel — core b) Position of the finish line;  Supra — best, hygienic maintenance  Equi — for gold crowns only, gingival 1/3rd  Subgingival — gingival 1/5th Shoulder – 1.0-1.5mm thick o All-ceramic crowns, coz edge strength of porcelain is low- so need but joint, 90 degree o For the labial side of Anterior PFM also, as it maximizes the aesthetics by eliminating the display of metal. o Bur used is – diamond end cutting bur Light Chamfer – 0.3-0.5mm thick o Mostly for gold crowns & Metal crowns o rarely in PFM o Preferred finish line For cast Gold restorations o Leaves adequate bulk for marginal strength with acute angle & produces minimal stress at the margin. Heavy chamfer - 1.0-1.5mm thick o Best for PFM, esp in posteriors o And some all-ceramic crowns o If not given enough thickness at the finish line, the lab will be forced to over contour the crown – means to increase the thickness at the margin – it will stick- bacteria will accumulate and eventually affect the gingiva o metal-ceramic labial only Knife edge o — SS crowns (subgingival)  Most important aspect of FPD abutment complex is its finish line.  margin of crown if brokn — causes caries  if caries at margin ----o marginal leakage ----o unsupported crown ----o redo crown  Failure of marginal caries — crown margin damage  Failure of margin of crown —caries

8 GEN 2022 · VENEERS  Etching porcelain veneer by 9.6 % hydrofluoric acid *  The amount of reduction in laminate veneer o 0.3 (gingival 3rd) o 0.5 mm (mid-facial reduction) o 1-2mm (incisal)  Grooves are made using tapered fissure

29 AGO 2020 · FIXED PARTIAL DENTURE THE PROCESS 1. Treatment planning a. See if abridge is possible b. Check the health of the abutment c. Check if we can follow Ante’s law d. Choose the pontic 2. Primary Impression-for temporary bridge 3. Crown preparation 4. Take the Impression 5. Pour cast 6. Provisional restoration 7. Crown from lab 8. Cementation ABUTMENT TEETH  It is not a part of FPD unit / Bridge itself !  Selection o Should have Well sounded periodontium o Must fullfill ante’s law o Caries if any must have been restored o Should be able to withstand force o Must be in alignment with the common path of insertion (not tilted cases)  Best abutment — ankylosed teeth - Diverging multirooted, curved roots preferred to fused, single conical roots  Least preferred — endo treated tooth - 3rd molar if it is tilted, short-fused root. ANTE’S LAW:- States thaaaat : Root surface area of the 2 orrrr three abutment teeth supported by bone should be greater than or at least equal to, to the root surface area of the tooth or teeth that is being replaced. Root/Crown Ratio:- 𝑅𝑜𝑜𝑡/𝐶𝑟𝑜𝑤𝑛 =2/1 --- ] 𝐼𝑑𝑒𝑎𝑙 𝑅𝑜𝑜𝑡/𝐶𝑟𝑜𝑤𝑛=3/2 ----- ] 𝑟𝑒𝑐𝑜𝑚𝑚𝑒𝑛𝑑𝑒𝑑 2 abutments 1 pontic 3 abutment teeth 2 pontics Remember, Crown is always the lesser no. It will be easy to remember if they alter the ratio position, 𝑅𝑜𝑜𝑡/ 𝐶𝑟𝑜𝑤𝑛 = 1/1 --- ] 𝑚𝑖𝑛𝑖𝑚𝑢𝑚 Cantilever for lateral Q. crown to root ratio: a. ideal 1-2 b. Optimum 2-3 c. normal 1-1.5 d. acceptable 1-1.

29 AGO 2020 · PARTS OF FPD/BRIDGE 1. Pontic – that we replace for the missing tooth 2. Crown /Retainer – that is placed on the abutment 3. Connectors – that connects the pontic with the crown & thereby the abutment teeth CONNECTORS: - >RIGID --- casted connectors --- fixed >NON – RIGID ---- key and keyway connectors— Tenon and mortise – male female design ---- Included when we are not able to get a coomon path of insertion ---- For example a tilted crown – wich will have an oblique path of insertion, compared to the path of insertion that is parallel to the long axis in the normal tooth on the other end of the bridge. ---- So we put the single crown 1st and then the bridge unit on it. Any connector in a PFM should have a min vertical height of 3mm PONTIC DESIGNS  Replaces the missing natural tooth / teeth 1. SANITARY / HYGIENIC  Can clean with brush  Best pontic in posterior*  Best overall pontic* 2. SADDLE/ RIDGE LAP SHAPE  1st type of pontic design  It grips firmly on the ridge both buccally and lingually, not giving any space to clean  Concavity on the center area ∴ food lodgement possible  Bad hygiene  Least preferred- Actually never use. 3. EGG-SHAPED / CONICAL  Conical shape  One point contact at the ridge  More hygienic than ridge lap  Less hygienic than sanitary pontic 4. MODIFIED – RIDGE LAP / SADDLE LAP  Touches ridge at labial / buccal aspect only  Mimics natural tooth – as it appears emerging from the gingiva labially  Good aesthetics  Best for anteriors 5. OVATE  Most superior aesthetics  In cases where there's a ditch – like in Recently extracted areas  Accident cases- replacing immediately after extraction..  It Touches the ridge at the center  Egg-shaped  Has great emergence profile

29 AGO 2020 · ANTERIOR CROWNS IPS impress — most esthetic Inceram — high esthetic + high strength — anterior deepbite Zirconia — high strength

29 AGO 2020 · Preservation of Periodontium: -  The disaster of crown / FPD — Overhanging /Overcontoured crown o food lodgement o could affect perio eventually  Biological width — junctional epithelium + connective tissue = 2 mm  If at aaalll we are going subgingivally – it is only for aesthetic reasons, otherwise never preferred.  Preserve about 3 mm for assurance of preservation of periodontium.

29 AGO 2020 · FERRULE EFFECT: -  Value = 1.5 to 2 mm — minimum height / length of crown after prep  Most important factor for placement of crown*  If not enough height o Surgical crown lengthening + clinical post and core o Orthodontic extrusion (#ed at gingival part)  Q. The degree of the inclination of an abutment, which can be used 15 – 25 º. TEMPORARY CROWN  Anterior — polycarbonate-Prefabricated crown-like cover *most esthetic than acrylic and composite  Transparent cellulose acetate covers-trim the template-fill it with material-stick it on the tooth and after setting remove the plastic cover.  Putty impression template  Materials used ----o PMMA- INDIRECT METHOD, EXOTHERMIC ----o Bis acryl composite is used for direct method, little brittle so good for single or short span bridge Try-in — if correct fit And final — poor fit is due to over contouring

29 AGO 2020 · LAYERS OF PFM  CORE METAL : cast metallic framework. Also known as coping  OPAQUE PORCELAIN : o first layer consisting of porcelain modified with opacifying oxides. o Mask the darkness of the oxidized metal framework o metal-ceramic bond o Initiate the colour  Final buildup of DENTIN AND ENAMEL PORCELAIN o Best tissue tolerated material o Highly glazed layer *