Amalgams final preparation

1. What is the composition of amalgam Silver –increases strength and expansion Tin-decreases strength and lengthens the setting

time Copper-increases strength, decreases tarnish and

corrosion and creep Zinc-prevents oxidation of the other metals in alloy

during the manufacturing process Mercury-wets alloy particles and decreases strength

in excessive amounts

2. What are different types of amalgam and trade names

Classification High copper and low copper Zinc and Zinc free amalgams Admix alloys Spherical alloys Lathecut alloysAdmixed alloys Dispersalloy (Densply) Valiant PhD

Spherical alloy Valiant Megalloy Sybralloy

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Lathe cut Indiloy (shofu)

3. Advantages and disadvantages of spherical and admixed amalgams.

Spherical Admixed

Faster set Increased strength due to Ag-Cu particles

Earlier initial strength Contacts easier to develop

Requires less condensation force Disadvantages – Slower set

Better adaptation around pins Needs more condensation force

Crown preps at same appointments Difficult around pins

(After 30 to 45 minutes)

4. Advantages and disadvantages of spherical amalgams Require less mercury than lather-cut, because they

have smaller and spherical particles which has smaller surface area and less spaces between particles

Easier to condense into areas of difficult access (around pins) because they provide less resistance to condensation pressures

Hardens rapidly when compared to lathe cut alloys Smoother for carving, burnishing and polishing

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Disadvantages-Difficult to achieve tight proximal contacts because of plashy nature

5. Advantages and disadvantages of lathe cut alloys Advantages-Easier to achieve tight proximal

contacts, because they resist the forces of condensation well

Disadvantages-difficult to condense around pins Harden more slowly-greater chances of marginal

fracture during removal of matrix band Not as smooth for carving and burnishing and

polishing when compared to lathe-cut

6. Advantages and disadvantages of Admixed alloys

Have the advantage of spherical alloys but not their disadvantages

Have the body of lathe cut when condensing Easily condensed with good adaptation High Cu admixed alloys are good and they do not

corrode (first hour 154 and 24 hours 413) Low copper alloys seals the margins fasters than

high copper as corrosion products are responsible for self sealing

7. What are the lining material available under amalgam

Calcium hydroxide Type-III GIC Type-IV ZOE

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Brand namesCalcium hydroxide Dycal

Life (Kerr)

GIC Vitra bondFuji II LCFuji Linning Cement LC

(GC)

ZOE Type IV Unmodified-Tempac (type III)

Cavitic (type IV)Polymer modified-IRM

(Type-III)

8. What are basic cavity preparation steps?

Initial – 1) Outline form and initial depth2) Primary resistance form3) Primary retention form4) Convenience form

Final - 5) Removal of any remaining infected dentin or old restorations.6) Pulp protection if indicated7) Secondary resistance and retention forms8) Procedure for finishing external walls

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9) Final procedures like cleaning, inspecting and sealing

Ideal Dimensions of amalgam cavity preparations

Ideal depth – 1.5 to 2mm 0.2 to 0.5mm into dentin Axial depth – 0.2 to 0.8mm deep in dentin Clearance 0.5mm gingival from adjacent

tooth Isthmus width – ¼th of the intercuspal

distance (1 to 1.5 faciolingually) Axial dentinal depth – around 0.5 to 0.6,

Root – 0.75mm to 0.8mm

Class-V – Axial depth 0.8mm gingival wall 1.25mm occlusal wall and 0.5mm

into dentin

9. Functions of matrix bands and wedges.

A) Matrix bands – Rigidity, rigid enough to withstand the forces while condensation.

B) Establishment of proper anatomical contoursC) Restoration of correct proximal contactsD) Prevent overhang marginsE)Provides good surface finish in proximal areas

which is difficult to finish.F)Wedges – Separation of teeth (helps in contact

breaking)

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G) Proper adaptation of matrixH) Prevent overhanging marginsI) Protect gingival tissues and rubber dam.

10. Types of matrix bands Tofflemire which is straight and contrangled Siqiueland which is wide and narrow Automatrix Compound supported copper band T band Pallodent matrix system Omni matrix

11. What matrix will u select and what will u check? Universal matrix (Tofflemire-straight and

contrangled) Advantages Used when three surfaces of posteriors are involved

or tooth has been prepared Position the band and retainer are fairly stable Retainer is easily separated from band Precontoured bands available – require little or no

modification after positioning around the tooth Bands are available with varying occlusogingival

measurements

Ivory No-1 matrix Advantages Adjustable metal retainer Provide the missing wall for the single proximal

surface restoration

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Varying size bands available

Automatrix Best indications Very large class II preparations especially those

replacing one or more cusps Advantages-Auto lock loop can be positioned

either facial or lingual surface with equal ease

Disadvantage Bands are not precontoured and development of

physiological proximal contours is difficult

12. Different between matrix and retainer? Two types With retainer Tofflemire Ivory no-1 Siqiueland Pallodent Without retainer Automatrix T-band (used in children) Compound supported copper band Mylar strip

13. How do you use matrix? Position the band Lesser circumferences of matrix and slot of retainer

is toward gingivally

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Burnishing – burnish pad first on resilient paper band with egg shaped burnisher to develop proper proximal contour

Placement – band should be 1mm beyond gingival margin

Evaluate with explorer the gingival margin of cavity for proper extension-beyond cavity margin

Evaluate proximal proper level of contact and proximal contour by placing mirror or buccal and lingual side with reflected light

It should be convex with contact and junction of occlusal 1/3rd and middle 1/3rd

Evaluate occlusally the location of contact buccolingually and reburnish if required either in mouth or remove retainer and do it out side mouth with flat back end of spoon excavator (VIIP)

Some times matrix band has to be cut in order to avoid injury to the gingival attachment

14. Resistance form, how do u achieve?

Flat pulpal floor Minimal extension of external wall Strong ideal enamel margins Sufficient depth to provide adequate thickness of

amalgam bulk 90 degrees cavosurface margin

15. Primary resistance form, how do you achieve? Flat pulpal and gingival floor

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Minimal extension to allow strong cusp and ridge areas (isthmus width)

Restricting occlusal outline from to area receiving minimal occlusal contact

Rounding sharp internal line angles to decrease stress concentration

To provide minimum depth of 1.5 to 2mm to provide bulk of the restoration

Box shape Bevel the gingival wall to get full length of enamel

rods

16. How do you achieve primary retention form?

Occlusal convergence of facial and lingual walls Dovetail design Occlusal convergence of mesiofacial and

mesiolingual wall of proximal box Secondary retention form can be achieved by Proximal locks Pins Slots Amalgam pins Coves

17. If recent filling is high what does the patient complain and how do you determine it

Sensitivity to cold Pain on biting Shiny spot if amalgam filling Determined with articulating paper

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Apical Periodontitis

18. What happens if occlusion is high or what are the symptoms of high point?

Pain or sensitivity on biting Patient feels discomfort Fracture of amalgam (if its high point) Patient may develop Para functional habit Patient may get facial pain Deviation of closure of mandible from normal position

19. How to check if occlusion is high (amalgam filling).

Ask the patient to close slightly and check visually the occlusal anatomy.

Check occlusion Check visually occlusal anatomy Ask the patient to bite lightly, if amalgam filling there

will be a shiny spot Check with articulating paper Check with shim stock – will not come out while

pulling during light closure Check occlusion – centric occlusion, lateral excursion

and excursive movements

20. What happens if occlusion is not high but there is gross excess of amalgam?

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Proximal overcountouring – overhang margin Plaque accumulation Food lodgment Gingival trauma Affects the periodontal health – inflammation of

surrounding soft tissues.

21. How will you remove excess amalgam?.

With amalgam carver or blade on proximal surface With proximal finishing stripes Green stone with pumice (remember there is no need

for post burnishing for high Cu amalgams).

22. Instructions to patient after filling For amalgam restorations-liquid food for 2 hours. No hard food chewing on that side at least for 24

hours Slight sensitivity may be present If any discomfort and sensitivity persisting more than

two weeks ask the patient to report to clinic for check up

Ask patient to come for polishing and finishing if indicated

23. If you restore an amalgam in a bruxer, won’t it wear away? Best material to use is gold

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To prevent wearing and to take initial loading fast setting spherical amalgam is better to use

Increase retention and resistance forms of the cavity preparation

Identify and remove the high points Ask not to bite or take any thing till the amalgam sets Night guard and occlusal splints should be considered Try to find out the etiology and treat the condition

24 .How do u restore amalgam in bruxer, wont it break away?

High cu spherical amalgam is used as it has early setting strength (262 Mpa)

Try to avoid centric holding stop from your cavity preparation

Use of proper cavity design to have good bulk of amalgam, so it resist the occlusal forces

Good resistance form should be obtained Avoid any high points after restoration Give occlusal splint advice patient no to bite any hard things

25. What is the best material for bruxer?

Cast gold restoration is best for bruxer Type –I small lesions without stress bearing areas Type-II inlay or onlay Type – III crown and bridge work Type – IV RPD frame work

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26. Do you burnish amalgam before or after condensation, if so why?

Precarve burnishing Is a form of condensation Produce denser amalgam at the margins of occlusal

preparation restored with conventional amalgam alloys (heavy strokes mesio-distally)

Marginal adaptability and faciolingually with large burnisher

Is a continuous process of condensation Better marginal adaptability Denser amalgam at margin Brings up the excess mercury to margins

Post carve burnishing Light rubbing action Improve smoothness and satiny appearance (not shiny) Denser amalgam (conventional) Is a viable substitute for conventional polishing High copper – no post carve burnishing – (it has no

significant effect)

27. When do you stop burnishing? On burnishing you achieve a smooth satiny surface. At

this time u stop burnishing

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28. How will you restore occlusion in amalgam restorations?

When occlusal surfaces are involved in the cavity preparation use articulating paper to register preoperatively the centric holding stops and excursive contacts so that these marked areas can be either excluded from the outline form or properly restored.

Proper condensation, precarve burnishing and carving Overcarving should be avoided – put the carver on

unprepared tooth surface parallel to margin to preserve continuity of surface contour across the margins and helps to prevent over carving

Check occlusion visually and by articulating paper Always check occlusal clearance or interference with

articulating paper in centric occlusion, lateral excursion movement and protrusive movements

29. What is the purpose of condensation?

Adaptation of the amalgam to cavity walls Eliminate void spaces that produce denser amalgam Decrease mercury content in restoration The ideal condensation time (21/2 to 31/2 minutes and

it may be high for high copper amalgam).

30. When is polishing of amalgam is done, and what is the purpose of amalgam polishing?

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Amalgam polishing is done after 24 hours (as crystallization of amalgam is not complete).

For high cu amalgams no need of finishing-less time for polishing, these are less susceptible to tarnish and corrosion

Purpose To complete the carving Refine anatomy, contour and marginal integrity To get the smooth surface of the restoration for

becoming self cleansing area To get tarnish resistance always use wet polishing with slow speed hand piece

to minimize release of mercury vapor and heating of amalgam restoration

If mercury is brought to surface it will appear cloudy. this will produce corrosion and loss of strength of amalgam and

Overheated amalgam may permanently damage pulp

31. How will u polish amalgam? What speed you will use to polish the amalgam Explain retention form in this particular case

Finish and polishing is usually done after 24 hours because crystallization is not complete. Finishing and polishing achieves tarnish and corrosion free amalgam

Check the occlusion with articulating paper, if discrepancy is present correct with pointed white fused alumina stone or green carborandum stone. If

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scratches are left with this use of rubber abrasive point is indicated to remove these scratches

Initiate polishing procedure by using a coarse, rubber abrasive point at low speed and air-water spray to produce an amalgam surface with a smooth, satiny appearance

If the amalgam surface does not exhibit this appearance after only few seconds of polishing, and if surface is too rough, resurfacing with a finishing bur is necessary, followed by coarse rubber abrasive point to develop the satiny appearance.

It is important that rubber points used at low speed to prevent danger of point disintegrating at high speeds and the danger of elevated temperature of the restoration and the tooth which may cause damage to the pulp

As an alternative to rubber abrasive point, final polishing can be done using a rubber cup with flour of pumice followed by a high luster agent, such as precipitated chalk

Interproximal surface may be smooth enough with matrix band and should be finished if accessible

Retention form-all steps of cavity preparation should be followed

Also depends on the type of restoration used

32. How do you do amalgam finishing? Check the occlusion with articulating paper and

evaluate the margins with explorer If both have be corrected then use white fused

alumina stone or green carborandum stone

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Stone’s long axis is held at right angle to margin Then re-evaluate the margin and occlusion Use large round finishing bur no 4/6 to remove

scratches (scratches are formed by white and greenstone)

Polishing Use coarse rubber abrasive point It will give smooth and satin appearance Here if you don’t get the appearance do the

finishing and polishing again High polishing Use medium and fine rubber abrasive point

Alternatively to rubber abrasive points use rubber cup with flour of pumice followed by precipitated chalk

33. How do you check contact area after restoration?

We usually check with dental floss (u hear click sound with tight contacts and if the dental floss frays (tear), contacts are not smooth and there may be overhangs.

Visually check for all embrasures (occlusal, gingival, facial, lingual)

Site of contact point posteriors – middle 1/3rd and anteriors – incisal 1/3rd

How to check proximal over counters – Visual Overhangs – Tactile sensation with explorers,

radiographs, dental floss.

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34. How does gamma 2 phase interfere with strength of amalgam

SnHg phase is gamma 2 phase and is weakest and least resistant to corrosion and so needs to be eliminated. In high Cu alloys tin has greater affinity to Cu and it forms tin-copper phase instead of tin-mercury phase. Tin-Copper phase is tarnish and corrosion resistance and is stronger than tin-mercury phase.

35 What is ditching.

Ditching is the deterioration of amalgam tooth interface on the occlusal surfaces as a result of wear, fracture or improper cavity preparation.

36 Which scale is used to measure ditching?

Visually Explorer drooping into opening Shallow ditching less than 0.5mm – polishing

is enough (no replacement) More than 0.5mm – fissure sealant or

composite replacement.

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37. What is amalgam creep?

Creep is time dependant deformation of amalgam under stress.

As strength increases - Creep decreases. To minimize creep – Decrease mercury – alloy

ratio Increase condensation pressure

38 .Will you add freshly mixed amalgam if it is insufficient-YES

39. Finishing amalgam for spherical amalgam immediately – YES

40. Where areas contact areas located?

Maxillary and mandibular incisors the contact area are located in incisal 1/3rd and more facially

Molars they are situated at junction between incisal 1/3rd and middle 1/3rd or in middle 1/3rd

When u go posteriorly contact points goes gingivally

So increase occlusal embrasures

41. How will u come to know the patient is suffering from Parafunctional habits?

History of early morning facial pain Pain of masticatory muscles

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Patient spouse complaining of grinding sound at nights

Early morning headaches History of stress or depression History of sensitivity Occlusal wear facets Generalized attrition Broken restorations

42. Bruxism-when u restore tooth in co? Or relieve it a little bit to prevent fracture

No, you need to restore tooth in CO and need to give splint otherwise it changes occlusion

43. Indications, advantages and role of complex restorations in overall treatment plan. Also give long term complications of these restorations

A) Indications – 1. When large amount of tooth structure is missing2. When increased resistance and retention form are

required3. When questionable Pulpal or PDL prognosis4. In case of acute and severe caries5. Final definitive restoration6. Foundations (core)

Advantages1. Protect pulp from oral cavity (oral fluid, bacteria

and thermal stresses)2. Maintain occlusion3. Control caries and plaque

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4. Cost effective5. Provide anatomical contour6. Keeps gingival healthier7. Conservation of tooth structure8. Cost effective

Disadvantages1. Dentinal micro fractures (pin holes, pin

placements)2. Increased micro leakage (with varnish and not

using amalgam bonding)3. Pulpal penetrations and perforations4. Tooth anatomy (difficult to produce contacts,

contours and anatomy)

Contraindications2. Esthetic demands3. Occlusal discrepancy4. Anatomic and functional considerations (Para

functional habits)

44. When and why u decide to reduce cusp

When the facial extension is 2/3rd from the primary groove toward the cusp tip, reduction of cusp is mandatory

When extensive caries or previous restoration undermines cusp and become weaker

Reduction is done to increase resistance form in order to eliminate weak cusp and to avoid cuspal fracture

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45. Measurements of cusp capping.

For amalgam - 2mm functional cusps and 1.5mm for nonfunctional cusps.

For porcelain – 2mm functional cusps and 1.5mm for nonfunctional cusps.

For metal – 1.5mm functional cusps and 1mm for nonfunctional cusps.

Complex Amalgam Restorations Functional Cusps for Lower Teeth - Buccal

cusps Functional Cusps for Upper Teeth – Palatal

cusps

Cusp capping for amalgam restorations (page-sturdervant-770)

Functional cusps – 2mm Non Functional cusps – 1.5mm The occlusal contour of the reduced cusp

should be similar to the normal contour of the unreduced cusp

Any sharp internal corners of the tooth preparation formed at the junction of prepared surfaces should be rounded to reduce stress concentration in the amalgam and thus improve its resistance to fracture from occlusal forces

When reducing only one of two facial or lingual cusps, the cusp reductions should be extended just past the facial or lingual groove,

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creating a vertical wall against the adjacent unreduced cusp

46 When do you use pins?

Indications of pins With few or no vertical walls When large amount of tooth structure missing When u need one more cusp capping When u need increased resistance and retention

form Final definitive restoration Core build up

47. Pins in Amalgam Restorations and their guidelines in placing?

Guidelines for placing pins The depth of the pin hole varies from 1.3 to 2mm

depending on the diameter of pins used. However the general guideline for pinhole depth is 2mm

Self threading pins are most retentive pins, but the pulpal stress is maximum, when pin is inserted perpendicular to the pulp

As the diameter of the pin increases the retention also increases, but potential effects on pulp may also increase due to more stresses induced

The pin extension into dentin and amalgam greater than 2mm is unnecessary for pin retention

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and is contraindicated to preserve the strength of the dentin and the amalgam

As a rule one pin per missing axial line angle There should be at least 1mm of sound dentine

around the circumference of the pin hole, this elicits minimal pulpal response

The pin hole should be positioned no closer than 0.5 to 1mm to the DEJ or no closer than 1 to 1.5mm to the external surface of the tooth, whichever distance is greater (before pin Hole location carefully probe gingival crevice to determine if any abnormal contours exist that would predispose the tooth to the external perforation

As a rule, the pinhole should be parallel to the adjacent external surface of the tooth

Whenever three or more pinholes are placed, they should be located at different vertical levels on the tooth if possible, this will reduce stresses resulting from pin placement in the same horizontal plane of the tooth

Spacing between pins, or the inter pin distance depends on the size of the pin used. The minimal pin distance is 3mm for the manikin (0.48mm) and 5mm for the minim (0.61mm). Maximum inter pin distance results in lower levels of stress in dentin.

Dangerous areas in pin placements

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Fluted and furcal areas should be avoided. Specifically external perforations may result from pinhole placement over following areas

Prominent mesial concavity of the maxillary first premolar

At the midlingual and midfacial bifurcations of mandibular first and second molars

At the midfacial, midmesial and middistal furcations of the maxillary first molars and second molars

Pulpal penetration may result from pin placement at the mesiofacial corner of the maxillary first molar and the mandibular first molar

When possible the location of pin holes on the distal surface of the mandibular molars and lingual surface of maxillary molars should be avoided, because obtaining the proper direction for preparing a pinhole in these locations is difficult because of the abrupt flaring of the roots just apical to the cementoenamel junction. If the pinhole is to be placed parallel to the external surface of the tooth crown, penetration into the pulp is likely

Preparation of Pin Hole No 1/4th bur is first used to prepare a pilot hole

(dimple) approximately one half the diameter of the bur at desired pin location. This will prevent the crawling of pin drill

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Determine angulation for twist drill. Place drill in gingival crevice and position it flat against tooth

Now move it occlusally into position without changing angulation obtained

Repeat the procedure and get correct angulation Now prepare pinhole in one or two thrusts until

depth-limiting portion of drill is reached With drill tip in its proper position and with the

hand piece rotating at very low speed (300 to 500 rpm), apply pressure to the drill, and prepare the pinhole

The drill tip should never stop rotating from insertion to removal from the pinhole to prevent the drill from breaking while in the pinhole

Placement of pins All pin designs can be inserted with an

appropriate hand wrench A conventional latch-type contra-angled hand

piece also can be used to insert any of the pins except the standard design (recommended for link plus and link series)

With hand piece, place the pin in it and place the pin in the pin hole and now activate hand piece at low speed until the plastic sleeve shears from the pin

A standard design pin is placed in the appropriate wrench and slowly threaded clockwise into the pinhole until a definite resistance is felt when the pin reaches the bottom of the hole. The pin should then be rotated one-quarter to one-half

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turn counterclockwise to reduce the dentinal stress created by the end of the pin pressing the dentin

If rubber dam is not used, a gauze throat shield must be place in order to prevent accidental swallowing

Once the pins are placed, evaluate their length. Any length of pin greater than 2mm should be removed

To remove the excess length of pin, use a sharp 1/4th or ½ or 169L bur at high speed and oriented perpendicular to the pin. If oriented in different direction, it may result in rotating the pin in clockwise. Also during removing pin, the pin may be stabilized with a small hemostat or cotton pliers

Now check for tightness of pin and now determine whether pins have to be bend, so that they will be within the contour of final restoration and to provide adequate bulk of amalgam between the pin and the external surface of the final restoration

Pins are not to be bent t make them parallel or to increase their retentiveness

However, occasionally pins are bend to condense amalgam occlusogingivally

When pins require bending, a TMS bending tool is used. The bending tool should be placed on the pin where the pin is to be bent, and with firm controlled pressure, the bending tool should be

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rotated until the desired amount of bend is achieved

A hand instrument such as condenser or spoon excavator should not be used, as they cause dentinal crazing or fracture of dentin. also the operator have less control with a hand instrument

Disadvantages or Complications with Pins Dentinal micro fractures Dentinal crazing Microleakage Strength of amalgam or composite could be

reduced Perforation of pulp Perforation into periodontal ligament and

furcation areas Fracture of pins Broken drills Loose pins and pinholes too large Tooth anatomy complicating the pin placement

48. Can u bend pins in attempt to provide more retention?

Pins can not be bend to increase retention or to make them parallel

Pins are bend to position them within the contour of restoration

To provide adequate bulk of amalgam To allow condensation of amalgam

occlusogingivally

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Pin bends with TMS bending tool, not with another instrument

49. How do you prepare pin holes?

After ascertaining position of pinhole from external tooth surface make starting pin hole with 1/4th round bur approximately one half the diameter of the bur

Purpose – accurate placement of the twist drill and preventing the slipping of the drill when we are placing hole

Prevent crawling once it begun to rotate Drill the pinholes with same size Twist drill in ultra slow hand piece (300 to 500

rpm) using only one or 2thrusts other wise it becomes wider hole

Never use dull drill (change drill after 20 uses)

50. With what materials the pins are made of? TMS pins are usually made up of titanium or

stainless steel plated with gold

51. What are the different designs available? Standard, Two-in-one, Self shearing and Link

plus and Link series The link series and link plus are recommended The Minuta, Minkin, and minim pins are

available in link series

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52. What are the different sizes of pins available and what is commonly used and why?

Four sizes of pins are available with corresponding color-coded drill

TMS – For severely involved posterior teeth Minikin pins – 0.48mm Minim pins – 0.61mm Minuta pins – 0.015 inch Minikin pins are generally used because of less

dentinal crazing and less perforations Regular pins has highest dentinal crazing and

perforations

53. What are different types of pins? Cemented pins Friction-lock pins Self-threaded pins (more retentive than all) some of the Self-threaded pins are Thread mate system Coltene/Whaledent Mahwah, Newjersy

54. What should be the dimensional retentive slots prepared in an extensive amalgam restoration.

Slot is a secondary retention feature and is place in transverse direction in dentin to resist horizontal forces. Slots should be convergent occlusally

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0.5mm occlusally 0.6mm gingivally and 0.6mm deep 2-4mm length, minimum greater than 1mm Should be away 1.5mm away from external tooth

surface Slot very close to pulp can cause pulpal

inflammation

Slot Preparations Slot is a retention groove in dentin whose length

is in a horizontal plane. Slot retention may be used in conjunction with pin retention or as an alternative to it

Slots are usually placed on the facial, lingual, mesial, and distal aspects of the tooth preparation

McMaster has shown that shorter slots provide as much resistance to horizontal force as do longer slots

The slot is placed in the gingival floor 0.5mm to 1mm axial of the DEJ. The slot is 1mm or more depending on the distance between the vertical walls

Slots are placed with 33½ inverted cone bur (or ¼th inverted cone bur. The width of the slot at apex is around 0.5mm and at base is 0.6mm and the depth is around 0.6mm. The length of the slot can vary from 1 to 2mm depending on the retention needed

An alternative technique is to prepare the slot initially with a no 169L bur, then ensure convergence by refining it with a No 331/2 bur

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Pin retention is used more frequently in preparations with few or no vertical walls. Slots are particularly indicated in short clinical crowns and in cusps that have been reduced 2 to 3mm for amalgam

Compared to pin placement slot require more tooth structure removal but are less likely to create micro fractures and perforations with pin placements

Remember that the slot depth can be of 0.5mm to 1mm in depth. The length can be also 2mm to 4mm depending on the distance between the remaining vertical walls

55. Proximal locks, coves and amalgapins and what are the uses?

Function: Counter the proximal displacement of restoration

Depth -0.5mm in dentin Length-if greater than 2mm vertical wall, it will

terminate at axiolinguopulpal point angle Diminish depth occlusally-if less than 2mm axial wall,

then proximal locks are extended occlusally to disappear midway between DEJ and enamel margin

Prepared with 331/2 or 1/4th round bur or 169L bur

Proximal Locks (page-705)

Proximal retention locks are place in axiofacial and axiolingual line angles (believed to

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strengthen the isthmus of class II restoration and are believed these locks are significantly better than axiogingival grooves in increasing the restoration’s fracture strength

To prepare a retention lock, No 169L bur is used with air coolant and reduced speed to improve tactile feel and control.

The retention lock is always placed 0.2mm inside the DEJ regardless the depth of the axial wall, which maintains the enamel support

Some operators prefer ¼th bur to cut the proximal locks. The rotating bur is carried into the axiolinguogingival or axiofaciogingival point angle and then moved parallel to DEJ to the depth of the diameter of the bur. It is then drawn occlusally along the axiolingual or axiofacial line angle, allowing the lock to become shallower and to terminate at the axiolinguopulpal or axiofaciopulpal point angle (or more occlusally if the line angles are less than 2mm in length)

Coves in amalgam restorations Coves are prepared in a horizontal plane and

locks are prepared in vertical plane Both of them are prepared before placement of

pinholes and inserting pins

Amalgapins Are circular chambers cut vertically into dentin to

provide resistance and retention from for the

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restoration, these features are called amalgam inserts

Studies by Seng (depth 1.4mm in diameter and depth) and Shavell (depth of 3mm with no 1156 bur) have shown that the resistance to displacement provided by amalgapins is similar to that provided by pins

It has been demonstrated that depth of 1.5 to 2.0mm is adequate for amalgapins and that an amalgapin with a diameter of 0.8 to 1mm is sufficient

burs used are no 33m or no 56 or no 1157 or no 1156 by shavel)

56. What are the causes of cuspal fracture?

Inadequate cavity preparation Improper restoration Heavily restored tooth Parafunctional habits Bruxism Malocclusion

57. How do you diagnose incomplete cusp fracture?

Exclude other causes of pulpal and periodontal pain

Pain on biting and while releasing Tooth slooth or orange wood stick or cotton roll

or rubber disk Duplicate the patient pain

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Transillumination Dyes-stain tooth Magnifying loops Indirect aid-ortho band, and sealant is place if

patient pains stops, diagnosis could be made in restored tooth some times cusp may fly off

while removing

58. Signs and Symptoms of CTS

Symptoms Experience cold sensitivity Sharp pain of short duration while chewing

Signs Cold sensitivity on pulp test Biting test will be positive Signs of Parafunctional habits Occlusal wear facets Evidence of malocclusion Heavily filled tooth or large restorations

59. Which tooth is more commonly effected in CTS and why

Lower mandibular molar is most commonly affected because there is some embryonic problem during development (This may be due to developmental weakness of the tooth.(incomplete fusion of areas of calcification)

In specific mandibular second molars are affected because this tooth is in the area of masticator

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muscle attachments, so takes the greater forces of mastication

Mandibular second molars, followed by mandibular first molars and maxillary premolars, are the most commonly affected teeth

More prone to development of caries Sharp lingual cusp Heavily restored teeth

60. Does the crack in crack tooth syndrome visible? Cracks rarely show up on radiographs Mesial-distal cracks can never be seen Buccal-lingual cracks will only appear if there is

actual separation of the segments or the crack happens to be at exactly the same angle as the x-ray beam

Taking periapicals from more than one angle and taking bite wings may increase the chance of catching a crack-induced defect early in its development

61. How often do you see a fractured cusp in a practice – once in a week

62. Oblique ridge considerations Preservation Of Oblique Ridge – Consider Always

Try To Preserve Oblique Ridge Be, It Provides Cross Splinting Support To The Tooth

Involve oblique ridge When less than 0.5mm sound tooth structure between

two cavities If deep fissures and If undermined

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63. What is the best material to restore buccal cusp of Premolar.

A) Indirect ceramic onlayB) PFM onlayC) PFM Crown or all ceramic crownD) Amalgam with pin

64. What is the thickness of the base – 0.75-2mmMOD restoration distal cusp reduction with pin retained amalgam. What kind of amalgam you are using High Cu Admix alloy-Dispersalloy or Vallian PhD

65. Marginal Ridge preservation.

Premolars its 1.6mm minimum Molars its 2mm minimum How would u achieve this – divergence of wall

distally or mesially rather than converging to prevent undermining of marginal ridge (169L BUR)

66. What is the function of dovetail?

It gives increased retention It prevents the mesiodistal displacement of restoration

67. What is the ideal width of the proximal box?

0.2 to 0.3 mm clearance from the adjacent tooth

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0.5mm clearance with gingival margin

68. Upper premolar, only buccal and lingual walls remaining what material will u use and what treatment options you have?

Amalgam build up with pin or without pins Composite with pin or without pins Gold inlay or ceramic onlay PFM crown All ceramic crown

69. What would happen if there is no adequate thickness of amalgam covering the cusp?

Chances of fracture of restoration Chance of fracture of tooth U can’t get enough resistance Amalgam has low tensile strength, low edge strength,

so enough bulk of material is needed to withstand occlusal forces

70. Why would u place slots with grooves for retention instead of pins in an extensive cavity for amalgam?

Advantage of slot-slots can use with short clinical crowns

Increased retention and resistance form by bulk of amalgam

Less chances of micro fracture Less chances of microleakage

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Less chance of pulpal perforations If placed within in 0.5mm of pulp wont produce pulpal

inflammation Less chances of creating internal stress on dentin

71. What are the forces acting on the restoration?

Occlusal forces - perpendicular to those forces of mastication that are directed in the long axis of the tooth

Masticatory forces Long axis of tooth Obliquely directed forces Laterally directed forces

What are the forces affecting on the restoration (urvi)

Vertical or oblique forces Occlusal forces Masticatory force in oblique or vertical direction Lifting forces

72. Why have u done your minimal cavity preparation like this, how did u know how big to cut it?

Minimal extension of facial and lingual walls to conserve dentin supporting the cusps as well as facial and lingual ridges thereby maintaining as much strength of remaining tooth structure as possible so remaining tooth structure has resistance to fracture

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This resistance is against obliquely delivered forces, as well as those on tooth’s long axis direction

extension also depends on the extension of caries and depends on amount of retention and resistance needed and the type of restorative material used

73. Why when we restore tooth, we have to follow contour of tooth and what happens with overcountour or undercountour?

Improper embrasure form-food will not deflect itself leading to food lodgment and periodontal problems

Difficulty in using dental floss Impinges on soft tissues Irritation to tongue Plaque and food lodgment due to improper deflective

action

74. Why do you not prepare the cavity for erosion cavities?

How do you get retention form for restoration? Erosion is a non-carious lesion No caries excavation needed Not a stress bearing area Depends on choice of restorative material For example GIC (chemical bonding),

composites(micromechanical bonding) – they do not need or require extensive cavity preparation

And at this areas these materials do not need excessive thickness to withstand occlusal forces

These material rely on adhesive systems for retention

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75. If the patient comes complaining of sensitivity after amalgam placement what will be the cause and how to overcome it?

Two reasons for sensitivity after amalgam placement Sometimes due to high points Sometimes due to open dentinal tubules after cutting

dentin Hydrodynamic theory – changes in the direct of fluid

are perceived as pain by mechno-receptor near the pulp

Tactile, thermal or osmotic stimuli can induce changes in fluid flow and elicit pain receptor

Treatment Correct the etiology Remove the high points with large round diamond

finishing bur and then polish with rubber cup with pumice

Block dentinal tubules before restoration with dentin bonding agent

Do not cut dentine overzealously in dry field Some times it could be normal discomfort which could

be relieved in few days

76. What are the causes of dentinal hypersensitivity, and how do u treat it?

Exposed dentinal tubules Erosion Attrition Gingival recession Caries lesions

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The degree of sensitivity is influenced by the number and size of the open tubules

Treating the etiology is prime important Fluorides Periodontal treatment of gingival recession Sensitivity tooth pastes Dentine bonding agents Use of liner are bases when even indicated Correction of Parafunctional habits if present

77. What are the characteristics of inlays?

Occlusal depth-1.8mm Proximal box – follows curvature of original tooth

surface Follow outline precise path of withdrawal Axiogingival groove- 0.2mm deep Gingival, proximal bevels – 45 degrees, 0.8mm width Width of box just pass contact area Axial depth – 1mm Buccal and lingual walls for retention Proximal clearance at gingival level from adjacent

tooth – 0.6mm Round all sharp angles Good conservation of buccal and lingual cusps

78. What is smear layer and why it should be removed?

If the tooth structure is cut or polished during dental treatments, the tubules orifices become occluded with debris called smear layer

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Smear layer consists of primarily of tooth debris but also contains plaque, pellicle and salines and possible blood and saliva

Smear layer occludes the dentinal tubules and forms a smear plugs

Smear layer decreases the dentinal permeability by 86%

Decreased diffusion of bonding resin Smear layer loosely adherent to the bonding system

79. How would you follow up the case?

Recall visits Checking for signs and symptoms clinically Vitality tests Radiographs Study models

80. Causes of pain in cusp fracture is due to the flexion of cusp during function leads to pain

81. Would you take radiograph before, during and after treatments?

Actually it depends on the treatment procedures I do, for endodontics and any other surgical procedures and periodontics we may need to take X-rays during and after treatments.

82. What would happen to tooth after trauma?

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May be asymptomatic for few days Pulpal necrosis, ankylosis, resorption, impacted, May be extruded, intruded or avulsion, Luxation or

subluxation Concussion

83. What will u do to provide fixation, flexible and rigid splints, why and for how long?

Flexible splint-Niti ortho wire 014 gauge – for avulsion and intrusion for one week Semi rigid –Niti – 016 or 018 gauge for root fracture,

alveolar fracture and severe Luxation – for 3-4weeks For stabilization of tooth, decrease discomfort of

patient and avoid occlusal interference

85. What is the action of Ca(OH)2 when used as a pulp capping agent

A) Direct pulp capping agent – It may stimulate the pulp to form secondary odontoblasts, which in turn produce a dentin bridge across the exposure site.

B) Indirect Pulp capping agent – If the pulp is healthy, secondary odontoblasts will differentiate and form a reparative dentin to further protect (thermal, chemical, mechanical protection)

C) Antibacterial property - High Ph of 11-12 bactericidal.

D) Hard setting calcium hydroxide is DYCALE) Ca (OH)2 in methylcellulose base – slow setting –

Pulpdent.

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86. What is the difference between setting and non setting calcium hydroxide and uses of each?

Hard setting is used in direct pulp capping procedure (dycal)

Non-setting (pulpdent) is used as endodontic intracanal medicament

Root fracture Perforation Apexification

87. What is the action of calcium hydroxide when it is placed close to the pulp – direct pulp capping

Direct Pulp Capping – calcium hydroxide dressing may stimulate the pulp to form secondary Odonoblasts which can produce a layer of reparative dentin called dentin bridge to seal the pulp form further insult and it also have bactericidal effects

Indications for direct pulp capping The exposure is small which is less than 0.5mm in

diameter The tooth has been asymptomatic showing no signs of

Pulpitis The hemorrhage from the exposure site is easily

controlled The exposure occurred in a clean, uncontaminated

field (such as that provided by a rubber dam The invasion of pulp was relatively atraumatic with

minimal physical irritation to the pulp tissue

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88. Indirect pulp capping indications and procedure?

Usually all soft infected dentin must be removed However if pulpal exposure is anticipated by the

complete excavation of all questionable dentin, indirect pulp capping indicated

Thin layer of remaining carious dentin (affected dentin (hard) is not excavated but is left intact

It is then covered with calcium hydroxide base and the excavated area is restored with temporary material

Proximity of calcium hydroxide material to the pulpal tissue promotes reparative dentin formation

Thus the questionable remaining dentinal area may re-mineralize and form a dentine bridge in this area

This re-hardening of questionable dentine area usually occurs in 6-8weeks

This procedure prevents frank pulpal exposure and prevents potential adverse pulpal response to such as exposure

Problems with polycarboxylate cementWhat instruction would you give the patient sensitivity for one month (if not RCT)

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