Presentation on theme: "Class II MODB Pin Amalgam"— Presentation transcript:
1Class II MODB Pin Amalgam March 9, STIClass II MODB Pin AmalgamThese notes are taken from Dr. Reisfeis STI online presentation and slides.Restoration of Broken-Down Teeth: Manual ; Sturdevant Website Presentations: Foundations & Class II MODB pin amal & Placing the Pin - Movie
2Restoration of the Broken Down Tooth Scenario: Restoration of broken teeth where large amounts of structure missing could be because of different things—fractured tooth, fractured restoration, or cariesSolution: Complex posterior amalgam restorations should be considered whenLarge amounts of tooth structure are missingWhen 1+ cusps need recappingWhen increased resistance and retention forms are neededPins, potholes and other retentive measures
3Complex Amalgam Restorations Causes for large amounts of tooth structure missing: (objective 1)Existing cariesPreviously placed restorative materialFractured tooth structureRemain tooth structure is weak
4Indications and Contraindications for Pin Amalgam There are a number of factors to consider when restoring a broken down tooth: (objective 2)1. Age and health of the patientExample: If the patient is 6 years old, you do not want to place a cast on the tooth. Build it up with a pin retained amalgam. Wait until the patient ages and tooth erupts to give it more length to place a crown.Example: If the patient is older, a cast takes more time and several appointments. Do a pin retained restoration of some manner.2. Resistance versus retention: Availability of resistance and retention form
5Indications and Contraindications 3. How does the tooth affect the overall treatment plan?Consider the function of the tooth and its relation to surrounding dentitionIf the patient has significant occlusal problems, then treatment may be contraindicatedClass IV are rare because small anterior teeth involvedCould be used on amalgam Class IV distal insical surface of canine4. What is the prognosis?5. EconomicsCast restoration is more expensive because of time and lab work6. AestheticsSilver fillings are not aesthetic for anterior teethThey may be used as:control restorations in teeth that have a questionable pulpal and/or periodontal prognosis,control restorations in teeth with acute and severe caries,definitive final restorations, orFoundationsIn a tooth severely involved with caries or existing restorative material, any tooth structure subject to potential fracture must be removed and restored properlyThere are designs for amalgam that improve resistance form of a tooth
6Resistance FormDefinition: The ability of the tooth and material to withstand forces—all the forces coming down—directed along the long axis of the tooth. (objective 3)Criteria for amalgam restorationFlat pulpal floorsCavity walls parallel to the long axisPreservation of cusps and marginal ridgesRounded internal line anglesAdequate thickness of restorative materialReduction of cusps when indicated
7Retention FormDefinition: The ability of the tooth to retain the restoration when tipping or lifting forces are applied. (objective 4)Criteria for amalgam restorationIt is placed to prevent restoration from being lifted out of the toothConverging occlusal wallsGrooves, pins, slots, steps, amalgapinsOcclusal dovetail (keeps it from going distally)Adhesive systems that bond amalgam to tooth structure
8Prognosis of the Tooth (objective 5) FinCore build-up in anticipation of a cast restoration (See network presentation Foundations)Interim restorationIRM or temporary crownSymptomaticCaries activityIf there is extensive caries, then a root canal might be necessary.If there is high caries activity, then you do not want to put a casting on this tooth.Control disease process first.Fracture potential of toothTooth structurePut a temporary restoration to see how the tooth reacts before placing anything permanent on there.
9Treatment Plan Considerations What is the tooth going to be considered for? (objective 6)Do not treat one tooth up in the clinic. Consider everything!Fixed or removable partial dentureIt is an abutment toothFinal Restoration—is the tooth for final restoration?Provisional restoration: or foundation or build upPeriodontal treatmentOrthodontic treatmentFinal restorations are desirable only until all orthodontic and periodontal treatments are finished
10Reasons for Controlling Restoration What does a controlled restoration achieve? When we control a restoration it:Helps to protect the pulp from the oral cavity (fluid, pH, thermal insults, changes, bacteria)Provides an anatomical contourHealthier gingival tissueFacilitate control of caries and plaqueProvide resistance against fractures
11Rules for Cusp RemovalIf unsupported tooth structure OR caries extension from primary groove to cusp tip is: (objective 7)½ the distance: NO removal is indicated½ to 2/3 the distance: Consider cusp removalOver 2/3 the distance: Remove the cuspFinal Amalgam must have 2 mm of thickness over cusp
12Rules for Cusp Removal (objective 7) ½ the distance: No removal is indicated½ to 2/3 the distance:Consider cusp removalOver 2/3 the distance:Remove the cusp
13Types of Auxilliary Retention More tooth structure lost = more auxilliary retention is neededPinsPulp ChambersYou get the most retention form from the pulp chamber.If this tooth had a root canal, then putting cast material or direct material into pulp chamber gives best retention.Amalgapins: Prepare a 1 mm deep hole wide enough for small condenser (see slide 14)Slots (see slide 15)Grooves: this is what we have been practicingBoxes: this is what we have been practicingPins, slots, and amalgam bonding techniques can be used to enhance retention form when there is not enough remaining tooth structure for conventional retention features
14Amalgapin Amalgapin Depth: At least 1 mm Width: It should be wide enough to receive a small condenser
15The SlotThe Slot#34 inverted cone provides a little bit of an undercutDepth: 0.5 – 0.75 mm deepWidth: 0.5 – 1.0 mm wideLength: At least 1.0 mm in lengthIt should be 0.5 mm from DEJ
17The Pin Retained Amalgam Advantages (objective 9)Conservation of tooth structure by pin placement vs. crown placement (indirect restoration)Less chair timeCast restoration requires multiple appointmentsIncrease in resistance and retention formEconomic factorsInexpensive restorative procedureA pinretained restoration may be defined as any restoration requiring the placement of one or more pins in the dentin to provide adequate resistance and retention forms. Pins are used whenever adequate resistance and retention forms cannot be established with slots, locks, or undercuts only.The pin-retained amalgam is an important adjunct in the restoration of teeth with extensive caries or fractures. 47 Amalgam restorations includingpins have significantly greater retention than those using boxes only or those relying solely on bonding systems
18The Pin Retained Amalgam Disadvantages (objective 9)Possible microfractures of dentinPreparation may create small fractures or linesMicroleakageDecrease in strength of amalgamMore difficult resistance formThere is at least 2 mm of restorative material over pin to have enough to resist form—occlusion from abovePossible perforations to the pulp or external surfaceFinal tooth anatomy difficult to achieve with large complex restorations
19Types of Pins Cemented Pins – 1958 (objective 10) .001 to .002 inch larger hole drilled in dentin
20Types of Pins Friction Lock Pins – 1966 Hole is .001 inch smaller than pin diameterTapped to place
21Types of Pins Self Threading Pins – 1966 .003 to .004 inch smaller holeScrewed to place.
22Factors Affecting Retention (objective 11) Diameter: greater diameter = more retentionNumber: more pins = more retentionOrientation: better if placed in a non-parallel mannerThreaded v. Non ThreadedThreaded have more retentive formType: from least to greatest retentionCemented friction threaded is better
23Factors Affecting Retention What should the length of the pin be?Over 2mm in dentin.024 Minimum pin fractures on removal.031 Regular pin – dentin fracturesOver 2mm in amalgam.024 Minimum pin fracturesBottom Line: 2 mm is an ideal length into dentin and amalgam for strength of the dentin and retention of the amalgam.
24Factors Affecting Retention How should the pin be angled?The pin should be bent to position with the contour of the final restorationIt should provide adequate bulk of amalgam between the pin and the external surface
26The Treadmate System: What Size Pin? (objective 12) Posterior TeethMinuta – WorthlessMinikin – May be helpfulMinum – Best and most used; recommendedRegular – AvoidFIG Four sizes of TMS pins.A, Regular ( inch [0.78 mm]). B, Minim (0.024 inch [0.61 mm]). C, Minikin (0.019 inch [0.48 mm]). D, Minuta ( inch [0.38 mm]).
27Where is a pin placed in posterior teeth? (objective 13) Know your pulp anatomy and external tooth contoursObtain a current radiographCheck exterior contour with the periodontal probePatient age (older patient: pulp recession)Locate the bulk of amalgamCheck occlusionPinhole:At least 1mm from DEJAt least 1.5 mm from external surfaceAt least 5mm between pins
28Amalgam Bonding Agents Amalgam does not bond to tooth structure unless an amalgam bonding agent is used.The primary advantages for amalgam bonding agents in most clinical situations are the dentin sealing and improved resistance form, but the increase in retention form is not significant.The primary advantages for amalgam bonding agents in most clinical situations are the dentin sealing and improved resistance form, but the increase in retention form is not significant.
29Amalgam Bonding Agent Indications Possible indications for amalgam bonding proceduresLarge complex restorationsFoundationsPreparations lacking ideal retention**Review typical cusp fracture sequence**ContraindicationsExisting quality mechanical retention (if you don’t need it, then don’t use it)
30Class II Outline Form Standard Class II MOD outline (objective 14) Extend buccally 1.0 mm distal to buccal groove – Do Not Stop in GrooveCervical length: Even with level of mesial boxIn general, the preparation is larger
31MOD Preparation Prepare occlusal amalgam preparation (objective 15) Extend to contact areasDrop proximal boxes in normal mannerOcclusal depth: 1.5 – 1.8 mm deep
32Cusp Reduction (objective 16) Extend out the buccal groove at the level of the pulpal floorRemove mesio-buccal cusp (#245)Establish gingival seat on buccal continuous with mesialmm in width
33Gingival Seat Establish gingival seat on buccal continuous with mesial 1.0 mm in widthAxial walls parallel with long axisOpen proximal contacts distally and mesio-lingually (GF 11, GF 12)
34Finalizing Preparation Plane the facial wall, gingival seat, and axial wall ( #10-11, GF 16)Establish S-Curves as necessarySmooth and finish all surfacesBevel axio-pulpal line angles and place retention (169L and ¼ round)Objective 17
35Pin Placement (objective 18) Instructor will place a "caries" areaPlace liner on pulpal floorKeep away from retentive areas and wallsThin layer – less than 1.0 mm thickIndicate placement of pinUse ¼ round bur to dimple
36Pin Placement Procedure Flat surface – perpendicular to pin holePrepare notch to receive pin (if necessary)Drill is able to go to depthCondensation of amalgam can occurPilot hole with ¼ round burConfirm angulation – better to hit pulp than to exit tooth
37Pin Placement Procedure Rotate bur at slow speed (400 rpm) in latch handpiece (check rotation)Enter in one fluid movementExit in one movementDrill should NOT stop turning at any timePlace pin in handpiecePlace pin in hole and activate handpiece until pin shears
38Pin Height and Pin Angle If necessary:Cut pin to lengthUse a small round bur or 169L cutting perpendicular to the pinHold base of pin with hemostatBend the pinEvaluate pin regarding contour of restorationProvide bulk of amalgam around pinTMS bending tool only
39Restoration (objective 19) Matrix placementCorrect wedging from lingualCondensation and carvingCondense around pinCusp contoursCusp inclinesCusp heightCusp tip placement