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

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.

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.

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

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.

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

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.

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.

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?

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

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.

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

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)

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

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

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)

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.

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.

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

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

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?

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

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

Adhesive system applied: Optibond FL Dentin primer, solvent evaporated

Thin layer adhesive Light cured 20 sec. Facial & lingual

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.

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

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

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

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

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

Contour margins before light cure

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.

Light cured 20 seconds each surface

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

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.

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

Final Facial View

Final Lingual View

three facial lobes occlusion adjusted Final Incisal View

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

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

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

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