BDS5 content + exam Qs Flashcards

Question

Exam Q: What factors do you need to consider when making a diagnosis for TSL?

Answer 1

- Age --> distinguish between physiological vs pathological TSL - MH --> GORD ('heartburn'), pregnancy, parafucntional habits (TMJ/TMD), psychological disorders (clenching) - Drugs --> protein pump inhibitors (lansorprazole)/ antacids = GORD | liquid meds can cause wear - SH --> stress, alcohol, occupation (wine tasting/ swimmers) - Diet history --> fizzy drinks, fruits, sugar

Answer 2

- Pt w restored abutment teeth - where implants are contraindicated - good OH - most favourable prognosis: lateral incisor replacement

Answer 3

Each abutment tooth has different physiological movements in magnitude & in direction. There may have also been an unequal distribution of occlusal forces on the abutment teeth. As a result, one of the abutments may have debonded (+ develop caries) while the other remained cemented

Answer 4

- rubber dam (split dam) - Use narrow diamond bur (or new pear shaped one) for porcelain element of crown - Use narrow tungsten carbide pear shaped bur to section metal - Always stop at cement layer - Keep cutting groove narrow & in midline of crown (easier to remove w/ flat plastic) - Make sure all of the metal is cut on buccal, occlusal & palatal aspects - consider ultrasonic o remove old cement debris from tooth surface

Answer 5

Metal types: 1) High noble metal alloys (Au-Pd-Ag) 2) Noble metal alloys (Pd-Ag) 3) Basic metal alloy (Ni-Cr, Co-Cr,Ti) Ceramic types: 1) synthetic GLASS-MATRIX ceramic, e.g. lithium disilicate (E-MAX - has more translucency/aesthetics & is etching) 2) glass-infiltrated GLASS-MATRIX ceramic, e.g. alumina 3) feldspathic GLASS-MATRIX ceramic 4) POLYCRYSTALLINE (oxide) ceramic, e.g. zirconia or alumina toughened zirconia (stronger, more opaque/slightly less aesthetic) 5) RESIN-MATRIX (hybrid) cermaic, e.g. resin nanoceramic (ideal for CAD/CAM)

Answer 6

- Metal : ○ Margin = 0.5mm ○ Non-functional occlusal reduction = 1mm ○ Functional occlusal reduction = 1.5mm - Metal-ceramic: need to add approx 0.5mm to where you will add ceramic: ○ Labial/Buccal margin = 1mm (to max 1.5mm if incisor)

Answer 7

Attrition: this is due to enamel contact between tooth and tooth or tooth and dental material (restoration). Worsened by parafunction (TMJ/ TMD problems) Erosion: acid dissolution due to a chemical process. Intrinsic acid --> morning sickness, GORD, binge drinking, swimmers, anorexia + bulimia | extrinsic acid --> fruit juices, wine, fizzy drinks, sugary drinks, polypharmacy Abrasion: TSL is due to friction with exogenous material forced over the tooth surface, mainly due to aggressive brushing. Abfraction: TSL presents as V-shaped crevices on the tooth cervical. This is due to transmission of forces from cusp tips to thin cervical enamel.

Answer 8

* Over-impression not accurate * Moisture control poor * Preparation not retentive - over tapered &/or inadequate reductions and does not follow contour of tooth * Cement not mixed properly and/or too thick * Margins not accurate - overextension, underextension, overcontoured or open margins * Occlusion incorrect – excessive loading e.g. interferences during lateral excursion, premature contacts

Answer 9

Zinc-oxide Eugenol (e.g. Temp Bond, self-curing but don't use straight after comp resto as eugenol inhibits cure of composite) Non-eugenol cements (e.g. Temp Bond NE, a ZnO & nonanoic acid like clove oil so contraindicated in clove oil allergy)

Answer 10

* Loss of interdental space and contacts e.g., tilting of adjacent teeth, which may obstruct the seating of the permanent crown * Changes in the occlusal relationship: e.g., over-eruption of opposing tooth, which can result in premature contacts when fitting the permanent crown * Gingival hyperplasia at the margins and deterioration of gingival health: e.g., gingival overgrowth may make margins not visible or subgingival * Exposure of dentinal tubules, which can damage the pulp of the tooth or compromise the seal of an RCT tooth

Answer 11

* Retained temporary cement or trapped gingival tissue – check to make sure neither of these are present. If residual temporary cement is present, then clean the preparation of it and remove any debris * Tight proximal contacts – check and adjust tight proximal contacts, and also check the original cast for damage to the stone in these contact areas. Conversely, open contacts need to be modified in the laboratory (gold solder or addition of ceramic) * Laboratory errors e.g., casting blebs, damaged or shipped dies or over/under-extended margins. Casting blebs can be removed with a bur. Over-extended margins can be adjusted from the axial surface using softlex discs. * Internal discrepancies or areas of interference – can be located by applying a dry aerosol indicator (Occlude), disclosing wax or impression-type materials (light-bodied silicone). Any imperfections can be ground with a bur or stone.

Answer 12

Temporary crowns are usually cemented using soft cements. These cements allow: easy removal of the temporary restorations (from more retentive preparations). This is important as temporary crowns are not to a long-term treatment and are to be replaced.

Answer 13

* Complete laboratory prescription and indicate that impression has been disinfected. This prescription must also be signed by the prescribing clinician at each stage of laboratory. It is a legal requirement that work entering the laboratory is accompanied by a written prescription from a qualified professional user. * Ensure any sharp areas of impression tray/any potential sharps are properly packaged/rounded-off to avoid sharps injury * Disinfection of the impression: o Rinse the impression under running water to remove saliva and blood o Shake off water over sink o Immerse impression in disinfection bath containing 'Perform' for 10 minutes o Rinse thoroughly under running water o Place impression in plastic bag and label

Answer 14

* Do they ever experience 'Heartburn', if so how often? * What does your daily diet typically consist of? do you consume fizzy drinks, fruit juices, herbal and fruit teas? * What is you occupation? do you ever feel stressed? * Are you currently taking any medications? * Do you have suffer from any medical conditions such as Gastro-oesophageal reflux, Anorexia nervosa, Bulimia nervosa? "

Answer 15

* Intrinsic causes: wear of palatal surfaces of upper anteriors and occlusal surfaces of posteriors * Extrinsic causes: Buccal surfaces of upper anteriors worn, occlusal and palatal surfaces of posteriors * Smooth, rounded polished and often shiny lesions * Rim of enamel around tooth (in anteriors) - perimylosis * Restorations can be standing proud of tooth structure"

Answer 16

* Take impression and jaw registration in RCP * Cast up in dental laboratory and mount in RCP * Build up teeth in wax, and show the patient - ensure they are satisfied * Take putty impression of wax build ups * Isolate tooth/teeth with rubber dam * Using putty impression build up palatal surface of tooth in composite. Putty index acts as a guide to build up to. Make sure margins are flush and smooth. * May require to build up prominent cingulum on upper central incisors to act as a occlusal stop for lower centrals. * Adjust occlusion, and ensure patient is comfortable and satisfied with result Following restoration: * Medical referral if required to treat systemic conditions such as GORD * Dietary advice and post-op instructions * Monitor patient's tolerance to increase in OVD"

Answer 17

* Weight – if patient is severely underweight (sign of anorexia nervosa) or of a normal weight (e.g., in Bulimia nervosa) * Hands – Russell’s sign (calluses on knuckles/hands) as with Bulimia nervosa * Enlarged salivary glands - Puffy cheeks (caused by repeated vomiting) * Dry eyes/skin * Hair – thin and brittle * Angular cheilitis * Reduction in OVD

Answer 18

* Composite build ups may chip off (if RCP is not equal to ICP) * Debonding and wear of composite (esp if bonding to dentine, where bond strength of composite is weaker than bonding to enamel) * Staining of composite * Erosion may resume the cause has not been addressed e.g. GORD Others: * If we are increasing the OVD the patient may struggle to cope with the change (it is generally advised that OVD should be raised no more than 5mm or leaving a minimum of 2mm of freeway space. The greater the change the more difficult it can be for the patient to adapt) * If give patient a splint but habits continue, acid may get under splint and cause rapid erosion of build ups and teeth as no saliva to buffer and acid is contained"

Answer 19

* Conservative preparation that satisfies retention and resistance form requirements: ideally 3% taper, 6% convergence angle, sufficient height * Structural durability - sufficient bulk to withstand occlusal forces * Ferrule effect * Well defined, supragingival margins (ideally if possible) * Does not invade biologic width

Answer 20

During occlusal reduction, follow the natural anatomy of the tooth. Incisor full ceramic reductions: - incisal surface: 1.5 mm - buccal surface: 1 mm in 2-3 planes following the contour of the tooth - palatal and cingulum: 1 mm - shoulder margin: 1 mm wide all around the preparation Premolar CMC reductions: occlusal: - non-functional occlusal: 1 mm - functional occlusal: 1.5 mm - functional cusp bevel: 0.5 mm - buccal surface: 1-1.2 mm (metal-ceramic side) with a 1 mm shoulder margin - lingual surface: 0.5 mm (metal side) with 0.5 mm chamfer margin Molar (full gold) reductions: - non-functional occlusal 1 mm - functional occlusal: 1.5 mm - functional cusp bevel: 0.5 mm - lingual/palatal & buccal axial wall margins: 0.5 mm (chamfer margin)

Answer 21

* Cheap & easy to use * Be able to record fine detail providing an accurate replica of the crown preparation (good surface detail and flows into small spaces accurately capturing crown margins) * Confer a degree of wettability (hydrophilic) * Dimensional stability (e.g. in transport) * Good elasticity & tear strength * biocompatibiloty w mucosal tissues

Answer 22

* Inadequate structural durability: crown may not be able to withstand occlusal forces * Metal or ceramic layer may be too thin, and therefore have a higher propensity to fracturing * Occlusal interferences e.g. premature contact with opposing teeth

Answer 23

* Tooth shade * What material to use and return date * Patient details (identification number) and dentist details * The actual prescription

Answer 24

- Stained or worn down / fractured - Microleakage / caries growing underneath - Natural dentition has aged & changed colour

Answer 25

1. Protects the prep (& tooth from sensitivity, microleakage or caries) 2. Maintains appearance / aesthetics 3. Maintain occlusal relationship & stops opposing tooth from over erupting 4. Maintain the interdental space & contacts 5. Maintain function (speech & mastication) 6. Confirm that tooth prep is adequate (taper & reductions) 7. To prevent gingival hyperplasia at the margins and maintain gingival health 8. To protect dentinal tubules from microleakage (even in RCT tooth)

Answer 26

1. Preservation of tooth structure 2. Cusp coverage (cover compromised w the onlay to protect them form fracture) 3. Occlusal reduction: 1-1.5mm 4. Axial wall taper: 6-10 degree taper 5. Margin design: butt joints, 45 degree bevel w 1-1.5mm length & 1mm shoulder

Answer 27

- Medium-large cavities where one or more cusps are missing - Cavities where coverage of one or more cusps is advisable to improve the prognosis of the complex restoration - Morphological modification &/or raising the posterior OVD - Cracked tooth syndrome - Multiple medium - large sized cavities in the same quadrant - Endodontically treated tooth

Answer 28

a fixed intracoronal restoration a dental restoration made outside of the tooth to correspond to the form of the prepared cavity, which is then luted into the tooth (Journal of Prosthodontic Dentistry, 2017)

Answer 29

a partial coverage restoration that restores one or more cusps and adjoining occlusal surfaces or the entire occlusal surface & is retained by mechanical or adhesive means (Journal of Prosthodontic Dentistry, 2017) Note: when you cover all the cusps, it's called an 'overlay'

Answer 30

* Amalgam ('Nayyar core for multi-rooted teeth') – fast setting & can prepare the tooth shortly after * Composite – placed under rubber dam for moisture control * GIC – only as space fillers, not to build up entire core Other considerations: * Build the core to full anatomy – will help with putty index etc * Ideally build the core once you have completed the RCT & same appointment under rubber dam * Use the automatrix if only one tooth

Answer 31

To retain a core (they don't reinforce teeth)

Answer 32

DIRECT POSTS (no casting or impression required) 1) Wrought pre-fabricated posts: - Gold - Titanium - Stainless steel - Aluminium 2) Fibre posts INDIRECT POSTS (casting & impression required, duralay technique or direct technique) 1) type 3 alloy (noble gold alloy) 2) Basic metal alloy (Ni-Cr, Co-Cr,Ti)

Answer 33

Use the larger palatal canal to create the hole for the post

Answer 34

Lower teeth: BUCCAL functional cusp Upper teeth: PALATAL functional cusp

Answer 35

Adhesive resin based cements - self-curing (panavia) - dual-curing

Answer 36

Conventional luting cement - Zn phosphate - RMGIC - GIC (e.g. aquacem)

Answer 37

- Photographs - Full mouth radiographs - Sensibility testing (repeat on multiple occasions) - Articulated study casts - Duplicate casts - Diagnostic wax ups - Mock up - Review wax up - Trays selected and adhesive prepared - Lab card written

Answer 38

- Under-extended margin = crown lies short of finish line of prepared tooth - Over-extended margin = overhang, margin of crown resto lies beyond finish line of prepared tooth - Open margin = margin w/in the finish line but there is space between the rest of margin & prepared tooth - Over-contoured margin = w/in finish line but contour of gingival 3rd show excessive bulk

Answer 39

- Cement dissolution - Plaque retention & affect the health of gingiva - Recurrent caries

Answer 40

Identity w dental floss, it wouldn't pass through & therefore must be reduced ○ Correct by: § Unglazed porcelain is easily adjust w cylindrical stone § Glazed porcelain adjusted w/ diamond impregnated silicone points or diamond polishing paste

Answer 41

Identity w dental floss, it would pass through too easily with no resistance (cotact point area would appear deficient & under-contoured) ○ Correct by: § repeat impression & adding solder to that area / adding porcelain (in lab)

Answer 42

Use futar-d and measure clearance with callipers or, go below the contact points with your margins even if it feels destructive

Answer 43

- Always take your preparation over the cusp tip & onto the axial wall but reduced length - Try and avoid finishing your preparation on cusp tip

Answer 44

Risk of fracture of that axial wall during lateral excursions/chewing

Answer 45

* If bleeding as subgingival prep, aim for at least completing prep and perfectly adapted provisional * Make your temp first, make sure margins & occlusion is well & then take your impressions for the lab & then cement your temp * Use sectional tray or lower tray on uppers & lowers to help avoiding drags in the putty

Answer 46

- Ferrule: amount of sound tooth tissue to distribute occlusal forces from post to tooth too - If you can't get ferrule, you can do surgical crown lengthening, lasers, electrosurgery

Answer 47

* Panavia is a resin-based cement used for definitive cementation of restorations such as permanent crowns * There are different types of Panavia systems, distinguished from one another by their curing mechanism. - For example, Panavia 21 is a self-cure system, whereas Panavia F 2.0 is a dual cure system – a bi-cure system that cures both chemically and via light activation A distinguishing feature of all Panavia systems is the presence of resins with a phosphate group (MDP) and a carboxyl group (4-META) that promote bonding to the Ca2+ in the tooth and metal oxide in ceramic or metal-alloy restoration (but no direct bond to precious metals) i.e., Panavia bonds tooth to metal * This molecular adhesion of the tooth and crown material results in a high compressive and tensile strength, useful for retention of the restorative material * Other contents may include, but are not limited to: Bis GMA, camphorquinone, DMPT, phosphorylated methacrylate molecule.

Answer 48

* For base metals e.g., NiCr you can simply etch the metal surface with hydrofluoric acid and this leaves an oxide layer for Panavia to bond to * For precious metals, this oxide layer doesn’t occur so they must be grit blasted with Al2O3 and SiO2 (sandblast). Then a metal primer is added to the metal surface and a silane coupling agent.

Answer 49

1) Undercuts in the remaining tooth tissue - undercuts in preparation help to retain cores. 2) Slots - slots are placed in the base of the cavity in horizontal direction and grooves are placed parallel to the long axis of the tooth 3) Grooves - provide retention by limiting path of insertion and by preventing the rotation of restoration 4) Adhesives - e.g. Panavia – core is retained using adhesive. Main disadvantage is that it cant be used in conjunction with pins, amalgapins, slots or grooves. They also do not bond to well to wet substances e.g. dentine 5) Cores (e.g., Nayyar core): amalgam (usually 1st choice) or composite"

Answer 50

* Fill over 50% of canal length * Leave 4mm of GP at apex. (minimum length of 4-5 mm of GP). No space between post and GP. * Extends well below bone crest - ideally at least an equal amount of post below and above the alveolar crest * Longer than crown height * Design: Parallel sided (offers more retention than tapered) * Diameter should leave at least 2mm of surrounding tooth tissue to reduce chance of fracture * Aesthetic (consider white carbon posts or fibre posts) * Roughen surface - better retention

Answer 51

Creates a high fulcrum, which is above the supporting bone. This leaves the tooth at high risk of horizontal fracture when forces are directed onto it, which could eventually lead to loss of the crown and tooth

Answer 52

* Tapered screw engages the dentine to gain retention * Stress is created within the tooth as the taper forces tooth tissue apart leading to tooth fracture"

Answer 53

Crown margins may encroach onto the biologic width (N.B. do not write biological width as this would be incorrect), which may result in: * Gingival inflammation * Loss of alveolar bone * Formation of a periodontal pocket "

Answer 54

* When retention is of utmost importance - threaded posts offer best retention * Smaller tapered roots e.g., lateral incisors

Answer 55

* Conventional gold cast not adequate to resist bending (unless in thick sections) - instead use wrought precious metal * For paraposts < 1.25 mm (red), use wrought post as this gives strength in thin sections "

Answer 56

A resin bonded bridge (or resin retained bridge or more recently a fixed partial denture) are minimally invasive fixed prostheses used to replace missing teeth. They are luted to tooth structures (primarily enamel), which has been etched to provide micromechanical retention for the resin luting agent (as defined by the glossary of prosthodontic terms).

Answer 57

* Resin composite luting cement – usually variants of Panavia * Panavia is a resin cement with the addition of a phosphonated methacrylate monomer. * It has a very high strength and offers superior bond strength than other types of cements. * Longer working time requires oxyguard to prevent oxygen inhibition – anaerobic set"

Answer 58

* Increased occlusal demands (versus anterior spans). * More load on bridge & bridge framework, * Surface area coverage of abutments may not be sufficient for dealing with magnitude of forces * Difficult to keep clean

Answer 59

A bridge that has an abutment or abutments at one end only, with the other end of the pontic remaining unattached "

Answer 60

* Minimally invasive and easier to clean as it is only fixed to one end * Less clinical time in comparison to other treatment modalities e.g., implants * Less expensive (in comparison to implants and removable options) * Less demanding to fit than all other forms of tooth replacement (although moisture control imperative) * Aesthetic and predictable restoration * If fails, complete dislodgement of bridge, which can be recemented

Answer 61

* Flexure of cavity walls results in flexure fatigue and fracture * Excessive occlusal forces on restoration e.g., because the restoration is high * Exogenous agents e.g., hard food during mastication "

Answer 62

* Signs and symptoms: pain with hot and cold fluids and on biting and or/release. Sharp pain with short duration. Long history of symptoms, may be difficult to localise tooth * Examination findings: heavily restored tooth, evidence of parafunction/bruxism habits, may be visible evidence of a fracture e.g., stained enamel fracture (although common not to see fracture thought), may be TTP * Special investigations: * Visual inspection with magnification * Removal of existing restoration (if one is present) * Tooth slooth/Frac finder – usually will have pain on release of pressure * Transillumination – uses fibreoptic light which is held against the gingival margin of the tooth to investigate for fractures. * Dyes * Sensibility testing – usually positive with an exaggerated response * Radiographs

Answer 63

* Resistance and retention form: optimal taper: 3% taper (and 6% convergence angle); and sufficient preparation height (longer preparations have more surface area and therefore more retentive) * Optimal finish: rounded line angles, smooth finish, no sharp line angles or corners * Marginal integrity: clear well-defined supragingival margins (where possible) not encroaching onto the biologic width * Structural durability: enough tooth structure to withstand occlusal forces * Adequate reduction e.g. occlusally, on functional cusps, buccal, palatal etc * Aesthetics and preservation of the periodontium * Preparation should follow natural contour of tooth e.g. occlusal table should be similar to that of tooth prior to preparation, not flat General consideration: a conservative preparation that satisfies all of the aforementioned attributes

Answer 64

Poly methyl methacrylate (PMMA) - Duralay Bis acryl composite - Protemp II, Quicktemp

Answer 65

* Crown margin finish lines may have been placed subgingivally, onto the biologic width * This results in gingival inflammation, formation of a periodontal pocket and loss of alveolar bone"

Answer 66

* OHI, PMPR * Place a new temporary crown which has proper fitting (use retraction cords to aid placement) and ensure that crown is seated such that it not encroach on the biologic width * Electrosurgery - involves removing the gingival overgrowth surgically * Crown lengthening - reshapes and recontours the gingivae surgically "

Answer 67

* Condensation silicones - poly dimethyl siloxanes * Addition silicones - poly vinyl dimethyl siloxanes (PVDMS) * Polyethers * Polysulphide

Answer 68

1. Hue: quality by which it is possible to distinguish one colour family from another i.e. red from yellow or green. It corresponds to the wavelength of light reflected by the teeth. 2. Value: an achromatic measure of the lightness or darkness of a particular colour, ranging from pure black to pure white (best determined by a black & white photo). High value = light shade, low value = dark shade. Value is considered the most important factor in colour determination. 3. Chroma: degree of strength or saturation of colour of a particular hue - describes the intensity or vividness of a colour.

Answer 69

Light scattering phenomenon caused by the presence of fine particles (opalizers)

Answer 70

1. Lighting conditions - tooth shade may vary under different light conditions. natural light vs. artificial light. If using artificial ideally use colour corrected artificial light source (5500 K) 2. Contrasts - value or hue-contrast effects - e.g. tooth may appear brighter in patient with dark coloured lip stick, therefore remove prior to shade match 3. Observer - eye fatigue can change the appearance of colours 4. Lip position, angle and distance 5. Tooth dehydration - e.g. following rubber dam placement. Tooth dehydration makes them appear whiter, therefore shade match before placement i.e. using "wet tooth" 6. Tooth preparation may also change its colour

Answer 71

Taper: The angle between one axial wall of the preparation and the long axis of the preparation Ideal taper = 3 degrees (with 6 degree convergence angle) Convergence angle: angle is defined as the angle between two opposing axial walls of a preparation and equals the sum of the tapers of two opposing axial walls Consider drawing a diagram to illustrate these definitions

Answer 72

- Aesthetics - Functional issues ○ Discomfort ○ Reduced chewing ability / speech impairment - Biological ○ Drifting of teeth & over eruption ○ TMD ○ Bone loss ○ Occlusal stability - Pt perception & self image

Answer 73

83% of unopposed teeth are likely to overerupt

Answer 74

51.6% of unopposed teeth likely have interferences with RCP or excursive movements.

Answer 75

1 - How did they lose their tooth? 2 - When did you lose it? 3 - Is it causing you trouble / functional issues 4 - Is there an aesthetic issue 5 - Check if there is any contact point on the opposing tooth or drifting / overeruption Over-eruption happens mostly in the first 2-3 years

Answer 76

1 - No tx 2 - Implants 3 - Bridges (RBB or conventional) 4 - Removal partial dentures

Answer 77

1) Benefits 2) Risks 3) Cost 4) Longevity, depends on: ○ Materials used ○ Type of restorative procedure ○ Patient parameters ○ Operator variables ○ Local factors (occlusion etc) 5) Maintenance

Answer 78

- Prolonged tx - Tx stress & discomfort - Subsequent problems w abutment teeth

Answer 79

Oral function was adequate where at least 4 occluding premolar units were left, depending on the age of the patient & preferably in a symmetrical position.

BDS5 content + exam Qs Flashcards

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