1. PIN RETAINEDRESTORATIONS

2. CONTENTS1. Introduction2. Definition3. Indications and contraindications4. Advantages and disadvantages5. Pins types and designs6. Pin placement factors7. Techniques for inserting pins8. Cavity preparations9. Complications and failures 3. INTRODUCTION Most of the teeth can be restored withamalgam and composite but when thetooth preparation is extensive due tocaries or other reason the remaining toothstructure is very less, it becomes difficultto achieve optimal resistance andretention form. In such cases dentin lock and slots areprepared in dentin 4. But when these retention features areinsufficient to provide desired retentionthen pin supported restorations areused In these cases pins support therestorative materials and resist theirdislodgment in severely damagedtooth 5. HISTORYIn 1958, Dr. Miles Markley introduced apractical instrumentation for the use ofa stainless steel cemented pin thatresulted in the extensive use ofcemented pins in dentistry 6. DEFINITIONPin retained restoration is defined as any restoration which requires the placement of pin/pins in dentin in order to provide retention and/or resistance form to the restoration 7. INDICATIONS Extensive tooth loss Questionable prognosis As a foundation Economics Age and health of the patient 8. CONTRAINDICATIONS Occlusal problems Esthetics Access difficulties 9. ADVANTAGES Conservation of tooth structure Appointment time Resistance and retention form Economics 10. DISADVANTAGES Dentinal micro fractures Lowered fractured resistance Strength of amalgam restoration isreduced Micro leakage Perforations Difficulty to achieve proper contours 11. TYPES OF PINS1. Cemented pins2. Friction locked pins3. Self threaded pins 12. CEMENTED PINS Developed by Dr.Markley to retainlarge amalgamrestorations Made of StainlessSteel They are used tobuild foundation afterendodontictreatment as theyproduce the leastamount of stress Offer less resistancethan the other pins 13. FRICTION LOCKED PINS Developed by Dr.Goldstein in 1966 Made of stainlesssteel More retentive thancemented pins Used in vital teethwith good accessand ease of tappingthe pins Cause craze lines orcracks 14. SELF THREADED PINS Developed by Dr.Going in 1966 Most popular typeamong all thedifferent type of pinsand extensively used Made of stainlesssteel or titanium pins Provide maximumretention among alltypes of pins Cause craze lines Used in vital teeth 15. CEMENTED PINS FRICTION LOCKED PINS SELF THREADED PINSStainless steel withStainless steel with Stainlessthreads or serrations threadssteel/Titanium with gold platingPin channel [0.020 Pin channel is 0.001 Pin channel is 0.015to 0.32] larger than smaller than pin size to 0.004 smallerpin size [0.018 to than pin size0.30]Luted with standard Taped into place with Placed by handluting agents malletwrench or contraangle hand pieceEase of placement Pin placement is Pin placement isdifficulteasy 16. CEMENTED PINS FRICTION LOCKED PINS SELF THREADED PINSLess internal Increased internal Increased internalstressesstress stressesLeast retentive 2-3 times more 5-6 times moreretentive than retentive than frictioncemented pinslocked pins 17. SELF THREADED PINS THREAD MATE SYSTEM 18. SELF THREADED PINS THREAD MATE SYSTEM 19. REGULAR MINIMMINIKIN MINUTALargestNext smallerDiameter isSMALLESTdiameter pins diameter pinslesser than SIZE of pinsCauses Lesser stress minim pinsThey are toomaximal are createdVery less risk small tostressLesserof dentinal provideCauses dentinal crazing adequatemaximum crazingGood retentiondentinalGoodretention Not widelycrazing retentionMINIM ANDusedRarely used MINIKIN ARE COMMONLY USED SIZES OF TMS SYSTEM 20. PIN DESIGNS 21. Standard 7mm longdesign They have flattened heads to fit into the hand wrench or handpiece chuck After placement the pin is reversed 1/4th turn to reduce stresses on dentin Pin height can be adjusted appropriatelySelf Avaliable in varying lengthsshearing They have flattened heads to fit into the hand wrench ordesign handpiece chuck During pin placement when the pin reaches the bottom of the pin hole, the head automatically shears off, leaving a portion projecting from dentinTwo in one It consists of 2 pins connected by means of a joint which servesdesign as a shear line for peripheral pin Total length is 9mm and 2 pins are about 4mm each They have flattened heads to fit into the hand wrench or handpiece chuck The handpiece need not be reloaded during insertion of more than 1 pin 22. Link series They have a plastic sleeve that fits into the latch typedesigncontra angle handpiece or a special plastic hand wrenchSelf shearingPin engages the dentin and the plastic sleeve can bediscardedCan align well into pin channelsLink plus Similar to link series designdesignSelf shearingAvaliable as single or 2 in 1 pinsThe major difference in this pin design is that pins havesharper threads and a tapered tip to decrease dentinal stresseswhile seating 23. ADVANTAGES OF TMS PINS Versatile design Wide range ofpin sizes Color codingallows ease ofuse Gold platingeliminatescorrosion Good retention 24. PIN PLACEMENT1. MECHANICAL ASPECTS2. ANATOMICAL ASPECTS3. MECHANO ANATOMICAL ASPECTS 25. MECHANICALASPECTS[PINS AND TOOTHSTRUCTURE]A] Stressing capabilities of pins Type of pins 26. Diameter of pins Pin depth anddentinalengagement Bulk of dentin Type of dentin 27. Shape of pinchannels Loose pins Irregularly shapeddentinal end of pins Ratio of dentinalengagement : pinprotrusion [ideal2:1] Number of pins inone tooth 28. Drill its use and function Stresses induced during shorteningpins Retentive features Inserting pins in stress concentrationarea of tooth 29. B] RETENTION OFPINS IN DENTIN Type of pin Pin depth anddentinal engagement Pin channelcircumferentialshape relative to thatof pin Inter pin distance 30. Type of cement Ratio of dentinal engagement : pinprotrusion [ideal 2:1] Type of involved dentin Surface roughness of the pins Mode of shortening of pins afterinsertion of pins Bulk of dentin around the pin 31. C] MICROCRACKING AND CRAZING Type of pin Proximity of pin to DEJ Induced stresses in involved dentin Type of dentin 32. MECHANICAL ASPECTS[PINS AND RESTORATIVEMATERIALS]A] Effect of pins on the strength ofamalgam and composite restorations Compressive strength Tensile strength 33. B] RETENTION OF PINS TO RESTORATIVE MATERIALS Type of pin Pin diameter Inter pin distance Pin length in restorative material Proximity of restorative material with thepin surface Surface material of pins 34. ANATOMICAL ASPECTS Knowledge ofanatomy Radiograph Outer surface oftooth Amount of dentin 35. Anatomical features Tooth alignment Cavity extent Effect of age or relative age on thepulp chamber 36. MECHANO ANATOMICALASPECTS FOR PIN PLACEMENT 37. TECHNIQUES FOR INSERTINGPINS Pin channel preparations Cemented pin technique Threaded pin technique Friction grip pin technique 38. PIN CHANNEL PREPARATION Twist drill No. 1,2,3 round burs Measuring probes or depth guage 39. CEMENTED PIN TECHNIQUEINDICATIONS Ideal technique Only technique for endodonticallytreated tooth Only technique to be used whenavaliable location of the pin is close toDEJ 40. Ideal technique for a sclerotized /tertiary / calcific barrier / highlydemineralized / dehydrated dentin For class IV restorations When there is limited bulk of dentin 41. PROCEDURE Preparation of pin channel Checking the surface irregularities ofpins Slow setting phosphate /polycarboxylate introduced by perioexplorer tip or lenticulo spiral at slowspeed Placement of pin using lock in ormagnetised tweezer or hemostat 42. Large amalgam plugger is needed tocheck the complete seating of the pin In case of class IV restorations,bending of the pins is to be donebefore cementation of the pin channel 43. THREADED PIN TECHNIQUEINDICATIONS Vital teeth Dentin to engage the pin is eitherprimary or secondary Minimum avaliable location is 1.5mmfrom DEJ If minimum pins are needed for therestoration 44. PROCEDURE Preparation of pin channel Pin is engaged to a driving device andpin is continuously threaded into the pinchannel until it offer resistance initiatedby the pin channel floor Desired length of the pin can be cutusing small bur and high speedhandpiece in the direction of threadingand with light intermittent touches Surface irregularities are corrected No bending should be performed 45. FRICTION GRIP PIN TECHNIQUEINDICATIONS For vital teeth When bulk of dentin is present [min4mm in all 3 dimensions] Only in the accessible areas 46. PROCEDURE Pin channel is prepared Checking the surface irregularities ofpins Put a colored mark on the pin toindicate the exact depth of the pinchannel using a measuring probe Pin is held in its place at the entranceof the cavity Concave headed seater is placed onthe pin 47. With the hammer light strokes aregiven until that colored mark Remove all the holding devices Check for cracks, chipped pieces orgrossed fractures 48. CAVITY PREPARATION Remove all carious and weakenedtooth structure Initial cavity is prepared withdovetails, boxes, grooves etc Facial and lingual walls are keptparallel wherever possible Margins are placed supragingivally 49. Areas to receive pins should be flatand perpendicular to long axis of thetooth. There must be enough dentin for pinplacement Weakened cusps should be reducedand occlusal contour should follow thenormal contour of the unreduced tooth PULP PROTECTION 50. CLASS II DESIGN Pins should be put in apically deepestand most peripheral parts of the cavity Pin should not be placed below thecusp Decreasing the stress concentrationon the pin Use of minimum number of pins withless diameter Placement of the pin should be suchthat theres enough restorative materialaround it 51. CLASS III AND CLASS IVDESIGNCLASS III Pronouncedgingival floor in 2dimensions mustbe made One pin pergingival floor issufficient 52. CLASS IV For unilateralclass IV, Lshaped cementedpin is sufficient For bilateral classIV, U shapedcemented pin isused 53. CLASS V DESIGN Pins are placed axiallyparallel to the adjacentproximal surface Pin protrusion shouldbe minimal Deep retentive groovesare placed Pins should be placedmidway in thepreparation but asclose to gingival wall aspossible 54. RESTORATION 55. COMPLICATIONS Drill breakage Pin breakage Loose pins Heat generation Dentinal cracks Perforation into pulpal space orexternal tooth surface 56. FAILURES 57. EFFECT OF PINS ON PULP Generally it responds positively andaccepts its presence without anyadverse effects Histologic evaluation revealsinflammatory response, necrotic tissueencapsulation, fibrous tissueregeneration and formation of predentin by odontoblasts Inflammatory reactions have beenobserved under all kinds of pins 58. CONCLUSION The prognosis of the involved toothand its role in overall treatment planhelps to decide the restoration to beplaced If amalgam is selected as therestorative material to be placed, pinsplaced in dentin improve the retentionof the restoration Pins have been extensively used inthe past to restore such badly broken 59. REFERENCES1. Principles and practices of Operative Dentistry Gerald T Charbeneau2. Text book of Operative Dentistry Nisha Garg3. Text book of Operative Dentistry Vimal K Sikri4. Operative Dentistry Modern theory and practice M A Marzouk5. Sturdevents Art and Science of Operative Dentistry6. Clinical Operative Dentistry Principles and 60. THANK YOU