FREEHANDING -THE FULL LEWIS
My first successful freehand case was a five surface lower second molar that was mesially tilted. The tilt precluded placing a Tofflemire retainer. Three of the margins were subgingival. The patient’s name was Lewis, so afterward, whenever we had something similar to do, we called it “The Full Lewis”.
FREEHANDING A SUBGINGIVAL MARGIN AS AN AID TO SUBSEQUENT TOFFLEMIRE BAND PLACEMENT
- A second application for this approach is the MODB/L restoration when the buccal or lingual cusp has fractured to the gingival line, and it is impossible to achieve band stability.
- The solution is to follow the steps below and freehand a margin until enough structure projects supragingivally to place the band.
- Very important: confine the freehand buildup to the facial or lingual surface – don’t build the cusp past the proximal line angles, because you want to wedge the band tightly interproximally, and excess freehanded resin at the line angles prevents proper adaptation of the band to the interproximal root. Excess resin puddled at the line angles disrupts the shape of the band, compromises its stability, impedes wedging and gives you big finishing problems in the line-angle area after the band is removed.
- Exaggerate the emergence angle of the build-up For example, if the buccal cusp is being free-handed, overcontour to the buccal. This creates an infrabulge, necessary to stabilize the Tofflemire retainer, and tends to set the band towards the gingival. This keeps the band engaged on the perimeter of the root. This excess contour is removed in finishing .
Only build up half the height of the missing cusp before matrixing- it is easier if the remainder of the missing cusp is built up inside the matrix. See Bandbender for the steps in creating a properly contoured matrix
STEPS TO FREEHAND AUGMENTATION
It’s pretty simple|:
- Cord the entire perimeter see Retraction Cord
- Make sure to use caries detector to disclose any plaque, and remove this plaque with an instrument see Caries Detector as a Plaque Disclosing Agent
- Cut the prep as usual; choose appropriate enamel bevels, shoe cusps as needed, eliminate dentin stress risers,see Dentin axioms cut back fluoridated reminerialzed amorphous enamel to etchable rod ends, see Enamel Axioms, establish a flowing cavosurface, etc.
- Make sure your saliva isolation is perfect, because you will need to take your time in reconstructing the tooth. The Hygoformic saliva ejector is ideal for the lower arch, accompanied by a silvered Dri-angle or Richmond Reflective Dri-Shield Plus in the buccal vestibule. See Isolation
- Use a light shield to prevent premature cure when sculpting resin freehand.See
LOWER ARCH ISOLATION
If a Dri-angle (silver side facing the tooth) is fitted inside the Hygoformic saliva ejector, it adds light to the field, absorbs saliva, and extends the placement time one has in a dry field.
UPPER ARCH ISOLATION
- Fit one or multiple dri-angles over the parotid gland orifice or orifices (bilaterally) to supply passive isolation. For active isolation, bend a normal saliva ejector to the junction between the tongue and retromolar pad to evacuate the back of the mouth. The Zirc Pink Petal is helpful in this application. See Isolation
- Here’s a devious trick for upper molars where a rubber dam is impossible to apply: place a Dri-angle flat on the tongue. This will protect the operative site from unwanted tongue-stabs. The tongue just sits there quivering with the Dri-angle hovering on its dorsum. The silvered Dri-angle also increases the light level in the mouth.
- Put on the yellow anti-curing light shield over the operating light to prevent premature increment cure and increase placement time.
- Complete the bond sequence and then place flowable on the subgingival margins in intelligent increments, going slowly. It is effective to place small increments and snap-cure them for 5 seconds. In this way you don’t allow excess flowable to puddle subgingivally. As the mass of flowable accumulates, cure for your usual full duration. Finish by applying flowable onto all remaining parts of the prep.
PREMIER CURE-THRU CLEAR MATRIXES
- Premier cure-through cervical matrix forms can occasionally be very helpful to begin the
- restoration’s emergence from the sulcus. A similar matrix with a blue tint is available from Garrison Dental.
- When used with finesse, these matrixes can reduce the amount of post-op finishing. Trial fit the matrix after preparation, after fresh cord has been placed, Hemostatic Etch and standard bonding protocol have been completed. Tune in to your tactile cues that reveal correct placement with best adaptation to the preparation perimeter. Try to ensure that the matrix also serves as a gingival retractor.
- If the matrix obstructs access for placement, remove the matrix after memorizing the tactile cues to placement. Ensure isolation is perfect and no bleeding is occurring. Then place flowable, reapply the matrix with the same tactile cues as before, and cure the flowable. Now the margin is sealed with minimum subsequent finishing required. Bring the finish line up to a slightly supra-gingival level with more increments of flowable and then build the restoration free hand or with a circumferential matrix from there.
Never use cure-through matrixes to apply a bulk of material unless you want to drive a huge quantity of material into the sulcus, and make post op finishing an iatrogenic nightmare.
- Warming the resin improves handling qualities, physical properties,and adaptation.See Heated Resins
- Lubricate the plastic instrument with ethyl alcohol (99% anhydrous) to aid in placing and shaping the resin. Do not use proprietary wetting agents for this, as they will instigate weak interfaces throughout the restoration. See ethanol instrument lubrication The surface appearance may also acquire mottling if bond is used as an instrument lubricant. Isopropanol is effective, but is more toxic than ethanol and is usually sold with 1% moisture, i.i., 99% pure, whereas ethanol is 99.999% pure.
Have the CDA blow a brief air stream over each increment to evaporate the ethanol.
LIQUID LENS AND BITE IN PLACE OCCLUSION
- When close to the right occlusal height, add a last bulk increment of resin, and cover both it as well as the opposing tooth with Zest Danville Liquid Lens,, a glycerine gel. Make sure that the mouth is free of any pools of saliva that may adversely contaminate the interface of this last increment and its underlying layers. Have the patient close into occlusion on this last increment. While they are still occluding, cure the resin from as many angles you can access, then have them open and cure to completion.
- Another technique developed by long-time study group participant Dr. Raymond Wong in Port McNeill, BC, is to cover the restoration with a transparent film like Saran wrap and bite in place, and then cure while in occlusion.
- Rinse off the Liquid Lens or remove the Saran Wrap and have the patient occlude on articulating paper to indicate centric contacts in the bulk of resin. If clear markings are not being established, coat the paper with Vaseline, and clearer markings should result, see Occlusal adjustment and verification
- Develop your occlusal anatomy around these marked points. Finish as usual. Use caries detector to help highlight surface irregularities or defects. See Caries detector to identify flash voids bubbles and irregularties
POST CURE AND COOLING THE TOOTH DURING PROLONGED CURE CYCLES
- After final shaping, see Shaping large restorations quickly post-cure the restoration from all angles to optimize surface hardness.
- Cool the tooth with syringe air or water/air and high volume suction as curing proceeds to mitigate overheating if using multiple high intensity cure cycles. Outputs greater than 2000mW are counterproductive. see Curing resins
You can see that this whole approach is designed to normalize the presenting structure so you can restore it like a MOD, which we already know how to do.