1. Single Tooth Indirect Class II MODB Pin Amalgam
March 9, 2009
Single Tooth Indirect Class II MODB Pin Amalgam
Restoration 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 caries
Solution: Complex posterior amalgam restorations should be considered when
Large amounts of tooth structure are missing
When 1+ cusps need recapping
When increased resistance and retention forms are needed
Pins, potholes and other retentive measures

3. Complex Amalgam Restorations
Causes for large amounts of tooth structure missing:
Existing caries
Previously placed restorative material
Fractured tooth structure
Remain tooth structure is weak

4. Indications and Contraindications for Pin Amalgam
There are a number of factors to consider:
Age and health of the patient
Example: 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 dentition
If the patient has significant occlusal problems, then treatment may be contraindicated
Class IV are rare because small anterior teeth involved
Could be used on amalgam Class IV distalinsical surface of canine
What is the prognosis?
Economics
Cast restoration is more expensive because of time and lab work
Aesthetics
Silver fillings are not aesthetic for anterior teeth
They 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, or
Foundations
In a tooth severely involved with caries or existing restorative material, any tooth structure subject to potential fracture must be removed and restored properly
There are designs for amalgam that improve resistance form of a tooth

6. Resistance Form
Definition: 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 floors
Cavity walls parallel to the long axis
Preservation of cusps and marginal ridges
Rounded internal line angles
Adequate thickness of restorative material
Reduction of cusps when indicated

7. Retention Form
Definition: 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 tooth
Converging occlusal walls
Grooves, pins, slots, steps, amalgapins
Occlusal 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 denture
Abutment tooth
Final Restoration
Provisional restoration: foundation or build up
Periodontal treatment
Orthodontic treatment
Final restorations are desirable only until all orthodontic and periodontal treatments are finished

9. Prognosis of the Tooth
FinCore build-up in anticipation of a cast restoration (See network presentation Foundations)
Interim restoration
IRM or temporary crown
Symptomatic
Caries activity
If 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 tooth
Tooth structure
Put 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 contour
Healthier gingival tissue
Facilitate control of caries and plaque
Provide resistance against fractures

11. Rules for Cusp Removal
If unsupported tooth structure OR caries extension from primary groove to cusp tip is:
½ the distance: No removal is indicated
½ to 2/3 the distance: Consider cusp removal
Over 2/3 the distance: Remove the cusp
Final Amalgam must have 2 mm of thickness over cusp

12. Types of Auxilliary Retention
More tooth structure lost = more auxilliary retention
Pins
Pulp Chambers
You 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
Slots
Grooves
Boxes
Pins, 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 Slot
The Slot
#34 inverted cone provides a little bit of an undercut
0.5 – 0.75 mm deep
0.5 – 1.0 mm wide
At least 1.0 mm in length
0.5 mm from DEJ

15. Slots, Amalgapins, Postholes
Slots, Amalgapins, Postholes, etc.
Threaded Pins
Slots

16. The Pin Retained Amalgam
Advantages
Conservation of tooth structure by pin placement versus crown placement (indirect restoration)
Less chair time
Cast restoration requires multiple appointments
Increase in resistance and retention form
Economic factors
Inexpensive restorative procedure
A 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 including
pins have significantly greater retention than those using boxes only or those relying solely on bonding systems

17. The Pin Retained Amalgam
Disadvantages
Possible microfractures of dentin
Preparation may create small fractures or lines
Microleakage
Decrease in strength of amalgam
More difficult resistance form
There is at least 2 mm of restorative material over pin to have enough to resist form—occlusion from above
Possible perforations to the pulp or external surface
Final 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 diameter
Tapped to place

20. Types of Pins Self Threading Pins – 1966
.003 to .004 inch smaller hole
Screwed to place.

21. Factors Affecting Retention
Diameter: greater diameter = more retention
Number: more pins = more retention
Orientation: better if placed in a non-parallel manner
Threaded v. Non Threaded
Threaded have more retentive form
Type: from least to greatest retention
Cemented 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 fractures
Over 2mm in amalgam
.024 Minimum pin fractures
Bottom 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 restoration
It should provide adequate bulk of amalgam betwewen the pin and the external surface

24. The Treadmate System Common Versatile Many pin sizes
Excellent Retentiveness
Color coding system
Corrosion resistant

25. What Size Pin? Posterior Teeth Minuta – Worthless
Minikin – May be helpful
Minum – Best and most used; recommended
Regular – Avoid
FIG 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 radiograph
Check exterior contour with the periodontal probe
Patient age (older patient: pulp recession)
Locate the bulk of amalgam
Check occlusion
Pinhole:
At least 1mm from DEJ
At least 1.5 mm from external surface
At least 5mm between pins

27. Amalgam Bonding Agents

28. Amalgam Bonding Agent Indications
Possible indications for amalgam bonding procedures
Large complex restorations
Foundations
Preparations lacking ideal retention
**Review typical cusp fracture sequence**
Contraindications
Existing 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 Groove
Cervical length: Even with level of mesial box
In general, the preparation is larger

30. MOD Preparation Prepare occlusal amalgam preparation
Extend to contact areas
Drop proximal boxes in normal manner
Occlusal depth: 1.5 – 1.8 mm deep

31. Cusp Reduction
Extend out the buccal groove at the level of the pulpal floor
Remove mesio-buccal cusp (#245)
Establish gingival seat on buccal continuous with mesial
mm in width

32. Gingival Seat Establish gingival seat on buccal continuous with mesial
1.0 mm in width
Axial walls parallel with long axis
Open 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 necessary
Smooth and finish all surfaces
Bevel axio-pulpal line angles and place retention (169L and ¼ round)

34. Pin Placement Instructor will place a "caries" area
Place liner on pulpal floor
Keep away from retentive areas and walls
Thin layer – less than 1.0 mm thick
Indicate placement of pin
Use 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 depth
Condensation of amalgam can occur
Pilot hole with ¼ round bur
Confirm angulation – better to hit pulp than to exit tooth

36. Placement Procedure
Rotate bur at slow speed (400 rpm) in latch handpiece (check rotation)
Enter in one fluid movement
Exit in one movement
Drill should NOT stop turning at any time
Place pin in handpiece
Place pin in hole and activate handpiece until pin shears

37. Pin Height and Pin Angle
If necessary:
Cut pin to length
Use a small round bur or 169L cutting perpendicular to the pin
Hold base of pin with hemostat
Bend the pin
Evaluate pin regarding contour of restoration
Provide bulk of amalgam around pin
TMS bending tool only

38. Restoration Matrix placement Correct wedging from lingual
Condensation and carving
Condense around pin
Cusp contours
Cusp inclines
Cusp height
Cusp tip placement