1. Class IV Preparation and Direct Restoration
RSD 810 Spring 2016
Class IV Preparation and Direct Restoration
By Rodriguez
referenced:
Fundamentals of Operative Dentistry
A Contemporary Approach
edited by Summitt et al
Sturdevant’s Art and Science of Operative
Dentistry, 5th ed. By Roberson et al

2. A Class IV Lesion is one that involves the incisal angle of an anterior tooth.
As such it involves 4 or more surfaces of the tooth.
For instance: MIBL, DIBL
The restoration of these lesions requires close attention to shading and contour of the remaining natural tooth.

3. Generally there are two situations which give rise to the class IV lesion:
1) Extension of a class III lesion
2) Trauma
Many techniques for restoration of these lesions are described in the literature.
Today we will introduce some fairly complex prep and restoration concepts which will allow you to be successful in managing these in the clinical situation.

4. Perhaps it started like this: a badly stained class III restoration
Old restoration removed
Undermined lingual wall may need to be removed
The class III becomes a class IV involving the incisal angle

5. Typical Class IV fractures: these occur suddenly as a result of trauma
Most commonly occur in children and young adults.
Why?
Fractures can not always be classified as strictly horizontal or vertical.

6. They often require no other preparation than a wide scalloped bevel.

7. There is generally no need for additional retentive elements.
Regardless of the etiology, the method for preparing the class iv lesion remains the same:
PPE
Health history and clinical exam including occlusal exam
Shade matching/color mapping
Anesthesia as needed
Isolation
Preparation
One must remove diseased or defective structure, protect vulnerable inner tooth as needed and prepare enamel by beveling.
There is generally no need for additional retentive elements.
Etched enamel will provide sufficient adhesive retention for the composite resin restoration.

8. There is generally no need for additional retentive elements.
Regardless of the etiology, the method for preparing the class iv lesion remains the same:
PPE
Health history and clinical exam including occlusal exam
Shade matching/color mapping
Anesthesia as needed
Isolation
Preparation
One must remove diseased or defective structure, protect vulnerable inner tooth as needed and prepare enamel by beveling.
There is generally no need for additional retentive elements.
Etched enamel will provide sufficient adhesive retention for the composite resin restoration.

9. 2) Occlusal Considerations
Preparation extension:
Margins should not be placed on centric stops or along the path of
protrusive guidance.
Why?
Retention and resistance form features may have to be added due to size and or heavy occlusion.
What does this mean?

10. Let’s take a closer look at this prep
MI Occlusal stops
Margin and bevel placement must be respectful of occlusion
Incisal edge

11. Beveling the cavosurface margin
The first bevel should be placed at a 45 degree angle using a flame shaped diamond. This bevel removes any friable enamel.
A second wide, shallow scalloped bevel may be placed primarily to aid in blending the composite and the tooth structure.
Width of a bevels varies from .25 to 2.0mm depending on the following:
the amount of tooth structure missing and the amount of retention necessary.
Remember that retention comes primarily by micromechanical bonding of the composite to the enamel and dentin.

12. 3) Shade matching/ and color mapping
What do you see?
Moderate to high incisal translucency
Reddish brown hue
Low to moderate chroma
Three distinct anatomical lobes
Mammalons essentially worn away
Distinct incisal and facial embrasures

13. 3) Shade matching/ and color mapping
A2 is chosen: combine A3 body and A1 enamel
These areas have increased chroma as compared to the lobed areas (thinner enamel)
These areas have increased translucency (no underlying dentin)

14. 6) Class IV (Traumatic Lesion) Preparation
Note the rough and jagged fractured enamel edges

15. 1) First take an alginate impression of fractured tooth, then pour in mounting stone. This is a “quick cast”
3) Next create a lingual matrix on the ideal wax-up.
2) Wax to ideal form on the quick cast

16. 6) Class IV (Traumatic Lesion) Preparation
First Bevel: 45 degree angle rounds the sharp friable edges
facial and lingual (if not in path of occlusion)

17. Second Bevel: 60 degree angulation and 2-3 mm wide scalloped shallow, on the facial only. This bevel has variable thickness, starts inside the DEJ, and feathers and disappears onto the enamel surface. It’s purpose is for esthetic blending. I fine diamond bur should be used, and may be followed by a medium grit polishing disk.

18. 45 degree lingual and Gingival (first) bevels: use round, football, or flame burs, SofLex discs. Bevel should start at the DEJ. Width is 1.0 mm.

19. Are they necessary or desirable?
Retention: Pins?
Are they necessary or desirable?
Even gold plated pins tend to develop surface oxidation over time creating unsightly black stain.
Studies have shown that it would be better for the restoration to be lost than to be held in by a pin.
Sturdevant

20. The esthetic restoration of the direct composite class IV requires operator skill and attention to detail

21. Inserting and Curing the Composite:
Why do we avoid thicknesses greater than 2mm when sculpting composite?
Can the next layer be placed directly without additional adhesive or wetting resin?
How long should curing occur?
What are the consequences of too short curing times?

22. Inserting and Curing the Composite:
Why do we avoid thicknesses greater than 2mm when sculpting composite?
One must ensure complete cure of resin
Can the next layer be placed directly without additional adhesive or wetting resin?
Yes, if the surface has not been contaminated
How long should curing occur?
20 seconds minimum from the facial and 20 seconds from the lingual. Darker shades and deeper preparations require longer curing times.
What are the consequences of too short curing times?
1)Inferior physical properties
2)unreacted monomer leaches out.
review

23. Mylar and a small wedge are very gently placed.
Etched 30/15 seconds
.5 mm beyond bevel,
Washed for 15 sec.
Concepsis 60 sec., lightly dried

24. Adhesive system applied: Optibond FL
Dentin primer, solvent evaporated

25. Thin layer adhesive
Light cured 20 sec.
Facial & lingual

27. Wrap a one-inch piece of Mylar around the adjacent tooth.
Apply a thin layer of Filtek A1 Enamel into the putty matrix, then firmly seat the Matrix against the lingual surfaces of the teeth and light cure for 20 sec.

28. Teflon tape
The first layer creates a thin lingual shell of enamel shade.
Note it’s translucency.

29. Dentin or body shade A3, blended into enamel layer
The second layer creates dentinal opacity

30. Teflon tape
Lobes created with body or dentin shade A3
Teflon tape
(imaginary)
The third increment is somewhat opaque and creates lobes and hints of mammalons

31. The Mylar “push/pull through” technique
Material is pushed toward
lingual using flat instrument
Interproximal
contact point
Final increment is Enamel shade and very translucent:
Gold Instrument, brush, composite instrument, very small amount of wetting resin

32. Teflon tape
Matrix (not yet cured) is removed by gently pulling through toward lingual

33. Contour margins before light cure

34. Lingual view before light cure
Gingival margins sealed and almost finished.
Another small increment may need to be pulled through to round the marginal ridge.

35. Light cured 20 seconds each surface

36. Big RED Sof-Lex disc
Diamond flame bur (LOW SPEED!!!)
30-fluted carbide finishing bur

37. Interproximal polishing strips
These strips are available in varying degrees of abrasiveness and also in a more narrow width. Remember to separate teeth slightly prior to smoothing the contact area.

38. It may be helpful to mark lobes and mammelons prior to polishing in order to not lose contours.

39. Final Facial View

40. Final Lingual View

41. three facial lobes
occlusion adjusted
Final Incisal View

42. Before Lesions may have developmental origin.
Note: teeth are very monotone and opaque.

43. Friday afternoon emergency. Tooth was not further harmed
Friday afternoon emergency. Tooth was not further harmed. No anesthesia necessary.

44. Monday morning emergency. Pt diagnosed with ADHD.
You’ve got 10 minutes tops to achieve treatment or refer.
The good news: the patient was not in pain
Gently prophy with flour of pumice slurry to remove gross plaque
Determine tooth shade
Isolate
Quickly and gently prep bevels on facial and lingual
Gently place Mylar matrix
Etch, Concepsis, Prime, Adhesive
Place composite resin as close to ideal shape as humanly possible
Shape, check occlusion, polish

45. Clinical case: Gross carious lesions MIBL #8 & #9.
Treatment plan options included:
1)Extraction (but teeth are asymptomatic and vital)
2)Full coverage crowns (out of patient’s range of affordability)
3)Direct Composite Resin restorations
Note the characterization