MANAGEMENT OF BADLY BROKEN DOWN TEETH (II) Dr. Nasrien Ateyah

MANAGEMENT OF BADLY BROKEN DOWN TEETH (II) Dr. Nasrien Ateyah

PIN-RETAINED AMALGAM RESTORATION Defined as any restoration requiring the placement of one or more pins in the dentin to provide adequate resistance and retention forms. Used whenever adequate resistance and retention forms cannot be established with slots, locks, or undercuts only. It has a greater retention than those using boxer or relying solely on bonding system.

PIN-RETAINED AMALGAM RESTORATION It is indicated for tooth with extensive caries or fractures. Rarely used in anterior teeth (Bonding Technique). In class V is rare (horizontal groove in the gingival & occlusal aspect).

ADVANTAGE Conservation of tooth structure Save time vs. cast restoration Economic Provide resistance & retention form

DISADVANTAGE Dentinal microfracture or crazing Microleakage around pin strength of amalgam Perforation of the pulp or external tooth structure

TYPE OF PINS 1. Cemented Larger than other pin Use Zn Ph cem or Zn Polycar cem 2. Friction locked pins Smaller Retained by resilience of dentin retentive than cemented pin With time dentin relax loose pin

TYPE OF PINS 3. Self-threading pin (TMS) Different size Threads engage dentin Depend on elasticity of dentin Most retentive (3-6 6 times) No corrosion (gold plated) Create horizontal & vertical stress Cause dentinal craze line (size of pin)

MOST CURRENTLY MARKED PINS HAVE: Metal thread separated Wider dentinal thread retained well in dentin Shoulder stop (to prevent putting stress at the end of pin channel)

TMS PIN (THREAD MATE SYSTEM) Regular 0.031 inch diameter Minim 0.024 inch diameter Minikin 0.019 inch diameter Minuta 0.017 inch diameter

TMS PIN (THREAD MATE SYSTEM) Available in Double shear (two pins in one) Gold plated, stainless steel or titanium alloy Inserted manually or with low-speed, latch-type type handpiece

FACTORS AFFECTING THE RETENTION OF THE PIN IN DENTIN AND AMALGAM Type of pin Self-threading most retentive Friction-locked intermediate Cemented least Surface characteristics Number & depth of the elevation on the pin (serration or thread) Shape of self-threading pin greatest retention

FACTORS AFFECTING THE RETENTION OF THE PIN IN DENTIN AND AMALGAM Orientation, number and diameter Non-parallel pin - retention Bending of pin not desirable Interfere with condensation of amalgam Weaker pin, fractured dentin no. of pin - retention crazing & fracture amount of dentin available amalgam strength

FACTORS AFFECTING THE RETENTION OF THE PIN IN DENTIN AND AMALGAM diameter of pin retention no., diameter, depth Danger of perforation on pulp or external tooth surface Interfere with condensation of amalgam and adaptation to pins Extension into dentin and amalgam Retention is not increase when depth of the pin 2mm in dentin fracture of dentin in dentin fracture of dentin in amalgam fractured amalgam If 2mm in amalgam

PIN PLACEMENT FACTORS AND TECHNIQUES Pin Size Depend on the amount of dentin available and amount of retention desired. TMS pin of choice is Minikin (0.019 inch) and Minim (0.024) Minikin risk of: Dentin crazing Pulpal penetration Potential perforation

PIN PLACEMENT FACTORS AND TECHNIQUES Number of Pins Several factors must be considered: Amount of tooth structure Amount of dentin available to receive pin safely Amount of retention required Size of the pin

PIN PLACEMENT FACTORS AND TECHNIQUES Number of Pins As a rule one pin/missing axial line angle should be used Excessive number of pins fracture the tooth weaken the amalgam restoration

PIN PLACEMENT FACTORS AND TECHNIQUES Location Several factors aid in determining pinhole location: 1. Knowledge of normal pulp anatomy & external tooth contour 2. Current radiograph of the tooth 3. Periodontal probe 4. Patient s s age

SOME CONSIDERATIONS: Occlusal clearance should be sufficient to provide 2mm of amalgam over the pin. Pinhole should be located halfway between the pulp and DEJ (0.5-1 1 mm inside DEJ) At least 1 mm of sound dentin around the circumference of the pinhole.

Such location ensures proper stress distribution of occlusal force Pinhole: Should be located near the line angles of the tooth Should be parallel to the adjacent external surface of the tooth (not closer than 1-1.5 mm) Should be prepared on a flat surface

If three or more pinholes are placed: Should be located at different vertical levels on the tooth ( stress if pin in same horizontal plane) Inter-pin distance depend on the size of the pin to be used For Minikin (0.019 inch) 3mm For Minim (0.024 inch) 5 mm Maximal inter-pin distance results in lower level of stress in dentin.

EXTERNAL PERFORATION MAY RESULT FROM PINHOLE PLACEMENT 1. Over the prominent mesial concavity of the maxillary first premolar. 2. At the midlingual and midfacial bifurcations of mandibular first & second molars. 3. At the midfacial, midmesial, mid-distal distal furcations of maxillary first and second molars.

PULP PENETRATION MAY RESULT FROM PIN PLACEMENT At mesiofacial corner of: Maxillary first molar Mandibular first molar When possible, location of pinholes on: Distal surface of mandibular, molars Lingual surface of maxillary molars Should be avoided

PINHOLE PREPARATION: No. ¼ bur used to prepare a pilot hole (dimple) To permit more accurate placement of the twist drill Prevent the drill from crawling once it has began to rotate Optimal depth of the pinhole into the dentin is 2mm (Omni-Depth gauge used)

PINHOLE PREPARATION: The hole should be prepared on flat surface and the drill perpendicular to it. Place flat thin-bladed hand instrument into the crevice and against the external surface of the tooth To indicate the proper angulations for the drill

PINHOLE PREPARATION: Place the drill tip in its proper position Hand piece rotating at very low speed Apply pressure to the drill Prepare pinhole in one or two movement until the depth-limiting portion is reached Remove the drill from pinhole

Using more than one or two movements, tilting the hand piece too large pinhole The drill should never stop rotating to prevent the drill from breaking while in the pinhole

PINHOLE PREPARATION: Dull drill frictional heat Cracks in the dentin To bend the pin TMS bending tool

INTERNAL STRESS CAUSE BY THE PIN BY: 1. space between pins 2. Channel 2mm deep 3. Pins parallel to occlusal force

The success of all amalgam restoration depend on Matrix: stability of the matrix Tofflemire Double matrix Copper Auto matrix

FAILURE OF PIN-RETAINED RESTORATION Occur at any of five different location: 1. Restoration fracture (failure within rest) 2. Pin restoration separation (at the interface between the pin and restorative material) 3. Pin fracture (within the pin) 4. Pin dentin separation (at the interface between the pin and dentin) 5. Dentin fracture (within the dentin) Failure is more likely to occur at the pin dentin interface

PROBLEMS THAT ARISE DURING PIN- RETAINED RESTORATION: 1. Broken drills and pins Twist drill will break if: Stressed laterally Allowed to stop rotating before removing from the pinhole Dull (20 holes) Pin will break During pending Over - screwed in the hole Solution: Leave it in place. Do another hole 1.5mm from broken item

2. Loose pins PROBLEMS THAT ARISE DURING PIN- RETAINED RESTORATION: Due to: Loosened while shortened with bur Pinhole prepared too large Solution: Remove pin, pinhole prepared with next largest size drill, appropriate pin inserted Drill another hole 1.5mm from original pinhole, close the other one with amalgapins or cement the pin

PROBLEMS THAT ARISE DURING PIN- RETAINED RESTORATION: 3. Penetration into the pulp and perforation of the external tooth surface: Either penetration is obvious if there is hemorrhage in the pinhole Radiograph can help sometimes. Pulpal penetration treated as a pinpoint exposure Ca OH and prepare another hole If patient complains of pain after that endodontic treatment

PROBLEMS THAT ARISE DURING PIN- RETAINED RESTORATION: Lateral Perforation: Occlusal to gingival attachment Pin cut-off flush with the tooth surface. Pin cut-off and cast restoration extend gingivally. Remove pin, enlarge hole and restored with amalgam.

Apical to gingival attachment Surgically remove the bone after reflecting the tissue, enlarge pinhole, restored with amalgam Crown lengthening and cast restoration cover the perforation.

Resin Bonded Amalgam Restoration

RESIN BONDED AMALGAM RESTORATION An amalgam restoration that has been bonded to the existing tooth structure through the placement of a resin dentin bonding agent followed by a viscous resin (or glass ionomer) liner into which the fresh amalgam is condensed while the liner is still unset.

AMALGAM ATTRIBUTES Proven clinical longevity despite being non- adhesive Various resistance/retention forms have been successful even in large restorations Long - term seal

AMALGAM DEFICIENCIES Amalgam is not adhesive Restorations are passive and do not significantly strengthen remaining tooth structure Mechanical retention/resistance form is provided at the expense of tooth structure Microleakage is present until corrosion seals the cavo - surface interface (process is much slower in high-copper amalgams)

ADVANTAGES OF RESIN BONDED AMALGAM 1. Minimize or eliminate microleakage 2. Enhance traditional resistance and retention methods 3. Increase the fracture resistance of the restored tooth 4. Permit more conservative restorations 5. Decrease marginal breakdown and ditching 6. Reduced incidence of postoperative tooth sensitivity

INDICATION Used for: Supplementing mechanical resistance feature in large, complex amalgam restorations especially those replacing cusps. When an improved initial seal is needed, such as after a direct or indirect pulp capping procedure in tooth being restored.

BONDING MECHANISM Dentin Interface micromechanical (formation of hybrid layer) Amalgam Interface micromechanical (interlock between viscous resin and fresh amalgam) Weak Links resin/amalgam interface and resin/dentin interface

SOME COMMERCIAL SYSTEMS All bond 2 with -Resin bonding agent -Liner F -Resinomer (BISCO) Amalgam bond plus (HPA) (Parkell( Parkell) Multipurpose resin bonding agents - Optio-bond (Kerr) - Scotchbond multipurpose plus (3M)

CLINICAL TECHNIQUE FOR RESIN BONDED AMALGAM RESTORATION Rubber dam isolation is essential for the best clinical results. Clean preparations and apply conditioner (etchant) to enamel and dentin following the manufacturers recommendations. Rinse and dry lightly. Do not desiccate the tooth. This step should be done prior to Matrix band placement.

CLINICAL TECHNIQUE FOR RESIN BONDED AMALGAM RESTORATION Apply dentin primer/sealer following manufacturer s s recommendations. Apply the chemically-cured cured resin bonding liner manufacturer s instructions.

CLINICAL TECHNIQUE FOR RESIN BONDED AMALGAM RESTORATION Condense the amalgam immediately into the wet liner before it cure. The resin will have a tendency to stick to metal condensers and you may need to wipe them frequently. You will find the bonding material will ooze out at the cavosurface margins and some of this excess can be removed before the material is completely set. Do carving as you can at this stage to minimize the finishing time. Try to keep excess resin off of adjacent tooth structure.

CLINICAL TECHNIQUE FOR RESIN BONDED AMALGAM RESTORATION Remove the wedge and matrix band carefully. If you have lubricated the band properly, this step should not present problems. Check inter proximal and cervical first. Scalpels and sharp chisels will help carve any resin at margins. Resin at Occlusal margins can be carefully removed with rotary finishing burs. Occlusal anatomy can be refined with carvers and rotary instrumentations.

CLINICAL TECHNIQUE FOR RESIN BONDED AMALGAM RESTORATION Remove rubber dam and check and adjust occlusions as necessary

DISADVANTAGES Extra steps and expense (both time and materials) Technique sensitive and messy Adhesive may stick to matrix, instruments and adjacent tooth structure Carving more difficult Finishing usually requires rotary instrumentation

CLINICAL TECHNIQUE FOR RESIN BONDED AMALGAM RESTORATION 1. Rubber dam isolation is essential for the best clinical results. 2. Current recommendations are to execute conventional amalgam preparation following traditional guidelines. It is possible to be somewhat conservative, but you must remember that the bulk of the restoration will be dental amalgam and that you cannot treat these as preparations for composite resin.

CLINICAL TECHNIQUE FOR RESIN BONDED AMALGAM RESTORATION 3. Clean preparations and apply conditioner (etchant) to enamel and dentin following the manufacturers recommendations. Rinse and dry lightly. Do not desiccate the tooth. This step should be done prior to Matrix band placement.

CLINICAL TECHNIQUE FOR RESIN BONDED AMALGAM RESTORATION 4. Carefully lubricate (very thin coat of Vaseline) matrix band and wedge. Do not contaminate conditioned tooth surface.

CLINICAL TECHNIQUE FOR RESIN BONDED AMALGAM RESTORATION 5. Apply dentin primer/sealer following manufacturer s s recommendations. NOTE: in systems that have a separate dentin bonding agent that is placed before the more viscous bonding liner is applied, apply that dentin bonding agent prior to matrix band placement

CLINICAL TECHNIQUE FOR RESIN BONDED AMALGAM RESTORATION 6. Apply the chemically-cured cured resin bonding liner manufacturer s s instructions. Current research indicates that the best attachment between amalgam and liner occurs with the more viscous materials.. In addition, it has been suggested that systems that have a fluoride release mechanism may be advantageous

The use of adhesive resins to increase the retention, resistance, and marginal seal of amalgam restorations has gained much popularity

The use of adhesive resins to increase the retention,, resistance, and marginal seal of amalgam restorations has gained much popularity

Several posterior teeth have anatomic features that may preclude safe pinhole placement Fluted & Fureal areas should be avoided.