Presentation on theme: "Single Tooth Indirect Class II MODB Pin Amalgam"— Presentation transcript:
1 Single Tooth Indirect Class II MODB Pin Amalgam March 9, 2009Single Tooth Indirect Class II MODB Pin AmalgamRestoration of Broken-Down Teeth Manual ; Sturdevant Website Presentations: Foundations & Class II MODB pin amal & Placing the Pin - Movie
2 Restoration 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
3 Complex Amalgam Restorations Causes for large amounts of tooth structure missing:Existing cariesPreviously placed restorative materialFractured tooth structureRemain tooth structure is weak
4 Indications and Contraindications for Pin Amalgam There are a number of factors to consider: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.Resistance versus retention: Availability of resistance and retention form
5 Indications and Contraindications 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 distalinsical surface of canineWhat is the prognosis?EconomicsCast restoration is more expensive because of time and lab workAestheticsSilver 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
6 Resistance FormDefinition: The ability of the tooth and material to withstand forces—all the forces coming down—directed along the long axis of the tooth.Flat pulpal floorsCavity walls parallel to the long axisPreservation of cusps and marginal ridgesRounded internal line anglesAdequate thickness of restorative materialReduction of cusps when indicated
7 Retention FormDefinition: The ability of the tooth to retain the restoration when tipping or lifting forces are applied.It 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
8 Treatment Plan Considerations What is the tooth going to be considered for?Fixed or removable partial dentureAbutment toothFinal RestorationProvisional restoration: foundation or build upPeriodontal treatmentOrthodontic treatmentFinal restorations are desirable only until all orthodontic and periodontal treatments are finished
9 Prognosis of the ToothFinCore 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.
10 Reasons for Controlling Restoration What does a controlled restoration achieve?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
11 Rules for Cusp RemovalIf unsupported tooth structure OR caries extension from primary groove to cusp tip is: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
12 Types of Auxilliary Retention More tooth structure lost = more auxilliary retentionPinsPulp 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 condenserSlotsGroovesBoxesPins, slots, and amalgam bonding techniques can be used to enhance retention form when there is not enough remaining tooth structure for conventional retention features
13 Amalgapin Amalgapin Depth: At least 1 mm Width: It should be wide enough to receive a small condenser
14 The SlotThe Slot#34 inverted cone provides a little bit of an undercut0.5 – 0.75 mm deep0.5 – 1.0 mm wideAt least 1.0 mm in length0.5 mm from DEJ
16 The Pin Retained Amalgam AdvantagesConservation of tooth structure by pin placement versus 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
17 The Pin Retained Amalgam DisadvantagesPossible 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
18 Types of Pins Cemented Pins – 1958 .001 to .002 inch larger hole drilled in dentin
19 Types of Pins Friction Lock Pins – 1966 Hole is .001 inch smaller than pin diameterTapped to place
20 Types of Pins Self Threading Pins – 1966 .003 to .004 inch smaller holeScrewed to place.
21 Factors Affecting Retention 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
22 Factors Affecting Retention How long should 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.
23 Factors 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 betwewen the pin and the external surface
24 The Treadmate System Common Versatile Many pin sizes Excellent RetentivenessColor coding systemCorrosion resistant
25 What Size Pin? Posterior Teeth Minuta – Worthless Minikin – 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]).
26 Where? Know your pulp anatomy and external tooth contours Obtain 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
28 Amalgam 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)
29 Class II Outline Form Standard Class II MOD outline 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
30 MOD Preparation Prepare occlusal amalgam preparation Extend to contact areasDrop proximal boxes in normal mannerOcclusal depth: 1.5 – 1.8 mm deep
31 Cusp ReductionExtend 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
32 Gingival 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)
33 Finalizing 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)
34 Pin Placement Instructor will place a "caries" area Place 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
35 Placement Procedure Flat surface – perpendicular to pin hole Prepare 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
36 Placement ProcedureRotate 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
37 Pin 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
38 Restoration Matrix placement Correct wedging from lingual Condensation and carvingCondense around pinCusp contoursCusp inclinesCusp heightCusp tip placement
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