HLT-001-003-Provisional Prosthodontic-90070.202521

Intra coronal

1.1. Introduction

Unit 3 covered fabricating a three-unit fixed partial denture (FPD) provisional restoration using the indirect-direct method.
A stay-vac matrix was formed using a study model of the waxed-up FPD model.
The matrix was trimmed in preparation to form the provisional at the appointment.
Provisional material was placed into the matrix, and the matrix was placed on the prepared teeth to form the TSF (temporary self-cure form) of the provisional.
This unit focuses on the direct method for fabricating provisionals.
An impression taken during the preparation appointment will be used as a matrix to form the provisional.
The unit builds upon knowledge and skills from previous units and general dental education.
Principles of intra coronal direct restorations are given, along with a sequential overview of placing an onlay.
Main procedures covered are fabricating, cementing, and removing a MODL onlay.
Information on fabricating an inlay is also included.
Practice exercises must be signed by the sponsoring dentist and submitted to the instructor.
A self-test is included.

Unit Objectives

Explain the principles of fixed prosthodontics for intra-coronal restorations.
Describe the sequencing of a procedure for an intra-coronal restoration.
Explain the direct fabrication of an ESF matrix for intra-coronal provisional restorations.
Explain the direct method of fabricating provisionals for intra-coronal provisional restorations.
Explain the removal of an intra-coronal provisional.
Describe an intra-coronal provisional for an inlay preparation.

Prosthodontic Principles of Intra-coronal Restorations

Referring to an inlay or onlay as an intra-coronal restoration might be a new concept.
Choosing an inlay depends on the patient's needs and the tooth's condition.
An onlay can conservatively restore a tooth with severely worn dentition.
Dentists use diagnostic tools to determine the best treatment.
Contraindication for inlay or onlay: Insufficient tooth structure to provide resistance and retention.
Creating an inlay may have a disadvantage if a suitable preparation cannot be achieved without undercuts, and if accessibility for the impression is limited.
Inlays may not be conservative of tooth structure, leading to the selection of an alternative treatment plan.
Margin design includes the term bevel.

Sequencing of Procedures for Intra-coronal Restorations

Pretreatment Procedures for an Intra-coronal Restoration

Dr. Adams has developed a treatment plan including a MODL onlay for tooth #2.6.
Pretreatment procedures include reviewing previous records, medical/dental history, vital signs, hard and soft tissue examination, aesthetic assessment, radiographs, and study models.
A consultation appointment is scheduled to discuss the design, materials, appointment details (length, procedures), costs, and to obtain informed consent.
After the consultation appointment, the intra-coronal restoration appointment can be booked.

1.2. Fabrication

Direct Fabrication of a Matrix for a Provisional Intra-Coronal Restoration

Richard’s preparation appointment is scheduled for 9:00 AM.
Jasmin, the prosthodontic assistant, prepares the operatory with instruments, burs, materials, and trays, similar to the setup reviewed in Unit 2.
Jasmin greets Richard, takes his blood pressure (within normal range: less than 120/80), and takes a shade for the permanent restoration.
Richard puts on safety glasses.
Dr. Adams and Jasmin put on their PPE (Personal Protective Equipment: safety glasses, mask, and gloves).
Dr. Adams performs an oral examination and checks occlusion before administering local anesthetic.
Safe recapping methods for needles include scoop technique, needle guard, needle capping device, and use of a safety needle.
While waiting for anesthesia, Jasmin prepares to take a putty impression using a single-quadrant tray and could use a closed-mouth impression using a dual-arch or triple tray.
Jasmin takes the upper-quadrant impression, ensuring proper seating and setting time.
After rinsing, Jasmin inspects the impression to ensure it meets specific criteria (refer to Unit 2, Practice Exercise 2).

Clinical Procedures for an Intra-Coronal Restoration

Isolation can be achieved using cotton products or dental dam.
Dr. Adams prefers dental dam and isolates teeth from #2.7 to #1.3.
Inversion of the dental dam material creates a seal and prevents crevicular seepage.
Dr. Adams begins tooth preparation with a 170 tapered FG bur, but may use diamond or other types of burs.
She creates a butt joint on the gingival walls, then uses a 7406 football finishing bur for a heavier chamfer margin on the lingual wall, and a 7901 tapered pointed finishing bur to place a slight bevel on the facial.
Jasmin performs thorough cavity debridement.
Jasmin mixes resin-modified glass ionomer cement (Vitrebond) to protect the pulp. Resin cements are insoluble in oral fluids but can irritate the pulp.
A thin $(\frac{1}{2})$ mm layer of Vitrebond is placed and light-cured.
Tissue management involves retraction using a single cord dipped in aluminum chloride solution.
Ferric sulfate solution is not recommended for non-metal restorations as it causes a darker reaction with gingival tissues.
The size of retraction cord is determined by the sulcus, a ‘v’ shaped crevice, with the goal of placing the cord halfway into the sulcus, usually 1 – 3 mm.
If the cord is too shallow, there may be inadequate space or, if the cord is too deep, material tearing near the edge of the preparation upon removal may occur.
Over-packing can cause irreversible gingival recession.
If an astringent solution is not used, mechanical displacement of tissue takes 10 – 15 minutes, compared to 5 minutes with chemical retraction.
If epinephrine-impregnated cord is chosen, the prosthodontic CDA cannot perform this service.
Epinephrine-impregnated cord acts as an astringent and vasoconstrictor, constricting blood vessels and providing hemostasis and ischemia (tissue shrinkage).
Contraindications for epinephrine-impregnated cord: heart disease, hyperthyroidism, or diabetes, or when taking certain drugs because they often present with hypertension.
Always review the patient’s medical history prior to treatment.
Jasmin removes the cord from the dappen dish, places it on a 2X2 to absorb excess liquid, makes a loop, and holds it over the preparation with the closed loop on the lingual and the tails towards the buccal.
Using a gingival cord packer, she gently packs the cord vertically to horizontally retract the gingiva and expose inter-proximal gingival margins.
The area is rinsed and left for 5 minutes.
After five minutes, Jasmin scans the final preparation to check the presence or absence of fluids and whether or not the gingiva appears displaced.
She removes the cord by gently grabbing the tail with a cotton plier, pulling it across the tooth, and not outwards towards the gingiva, checking it is intact.
If the site had fluids present or the margins were not clearly visible, additional methods of retraction could be indicated, such as injecting local anesthetic or using a cotton ball dipped in astringent.
Surgical retraction, using a surgical knife to excise tissue or electrosurgery (high-frequency current with a small electrode), may be an alternative approach.
Electrosurgery is contraindicated for patients receiving radiation therapy, with cardiac pacemakers, or diseases that slow healing.
Laser therapy is a less invasive alternative with faster healing time.
The final scan is completed with the opposing arch and bite registration.
Jasmin uses a bisacryl material for the provisional, as the preparation is an area of low strength. This will require cement.
For an inlay, a modified microfilled provisional material such as Fermit N by Ivoclar Vivadent may be used, using a matrix and wedge technique. This would require no cement.
Jasmin checks her armamentarium and reseats Richard.
She checks the impression, shakes out any droplets of water, and gently dries it with air.
After checking the impression, she rinses, isolates, and dries the prepared tooth.
Jasmin mixes and loads the bisacryl material into the matrix and seats it over the prepped tooth.
After 2-3 minutes, she removes it from the mouth and allows it to cure outside of the mouth for an additional 5 minutes.
There is little to no shrinkage, so the next step is to place mandrel and selected disc with a slow handpiece in preparation for trimming.
She uses a pencil to mark the margins and trims the excess.
After trying it in the mouth and checking the margins, contacts, occlusion, and aesthetics, Jasmin is satisfied and calls Dr. Adams for a check.
After receiving Dr. Adams’s approval, Jasmin polishes the provisional with a long shank rag wheel and flour of pumice at chairside, before rinsing it clean.

1.3. Cementing

Cementation Procedure

Jasmin checks the tooth preparation to make sure that it is free from debris, saliva, and blood; contaminants and moisture will reduce the effectiveness of the provisional cement.
Jasmin checks that the cord has been removed before she rinses and gently dries the preparations, careful not to over dry as this could cause post-operative sensitivity.
A cotton roll is placed in the vestibule before Jasmin mixes the non-eugenol provisional cement, placing a small amount on the TSF of the provisional.
She then seats the intra-coronal provisional with finger pressure on the prepared tooth and uses a mirror and explorer to check that it is properly seated.
When she is satisfied that it is seated, Jasmin inserts a cotton roll for Richard to bite on.
The cement is allowed to set for the manufacturer’s recommended time.

Removal of Excess Provisional Cement

It is important that all cement be removed as it can act as a physical irritant and contribute to plaque retention, causing an adverse tissue reaction.
Jasmin carefully removes the excess using an explorer, appropriate hand instrument, floss and air before rinsing the area thoroughly.
After Jasmin does a final self-evaluation of the cement removal, she asks Dr. Adams to check for remaining cement and for the final position, as Dr. Adams is responsible for Jasmin’s work.
Afterwards, Richard receives a final rinse and he is returned to an upright position.
At this point in the appointment, Jasmin gives Richard the post-operative instructions.
She escorts Richard to the front desk and confirms his next appointment before saying good-bye.
In the operatory, Jasmin completes the chart entry.
After cleaning the operatory, Jasmin’s final responsibility is to prepare the lab slip and have Dr. Adams sign it before calling the dental laboratory to ask their driver to pick up Richard’s disinfected and bagged final impression, along with Dr. Adam’s lab prescription and any other patient records.
When Jasmin is writing out the prescription, she makes sure to include the shade of the Polymer material that will be used to create the onlay.
The onlay material decision relies on operator preference, Polymers have a good record of use and can polish to a high lustre.
Jasmin has Dr. Adams review the lab prescription, authorized it and sent the scan to the lab.

Removal of Intra-coronal Provisional and Residual Cement from the Preparation

Richard returns to the office later for placement of his permanent onlay. After seating, Richard is asked how the tooth felt over the last two weeks. With no complaints, Jasmin prepares to remove the provisional.
Forceps or hemostats could compromise the margins. Jasmin uses a sharp instrument to break the seal.
She immediately inspects the TSF to see if the cement is stuck to the provisional and not left on the tooth, indicating adequate protection by not over-drying prior to cementation.
Jasmin uses a perioaid with a rounded tooth pick to gently remove any residual cement from the tooth surface.
She then places a wet 2X2 over the tooth to keep it from drying out while she waits for Dr. Adams to come in and fit the prosthesis.
Dr. Adams checks the margins with an explorer.
She asks Jasmin to place and hold a PFI instrument on the occlusal surface to hold the onlay in place as she flosses. Dr. Adams is happy with the tight, broad flat contacts.
Jasmin then transfers a dry 2X2 and articulating paper so that Dr. Adams can check the occlusion, which appears accurate.
The shade appears correct, so they are ready for final cementation.
Dr. Adams takes off the onlay and picks up the high speed handpiece with a coarse diamond friction grip bur attached to roughen the TSF and enhance the mechanical retention. She then leaves to go to the lab to sandblast the TSF, making sure to avoid the margins. This procedure will enhance the mechanical retention and also clean the TSF.
Dr. Adams has asked Jasmin to prepare resin cement. From your education you know that resin cements do not adhere to metal/ceramic or polymer material.
In addition to the mechanical retention, Dr. Adams must also prepare the tooth with a silane coupling agent to produce a chemical bond between the resin cement and the onlay restoration.
While Dr. Adams is out of the operatory, Jasmin uses a soft ribbed cup, flour of pumice and water to further clean and prepare the tooth.
She then places a cotton roll in the vestibule to isolate tooth #2.6.
Dr. Adams returns and asks Jasmin to mix dual curing hybrid resin cement. The brand chosen has a separate self-etching primer that is microbrushed onto the prep for a prescribed time.
The self-etching primer occludes the dentinal tubules which in turn diminish post-operative sensitivity.
Jasmin transfers the microbrush and then, using the air water syringe, carefully blows air for one second, aiming the stream of air down the long axis of the tooth.
Dr. Adams applies the primer to the surfaces and it is allowed to sit for the prescribed time before Jasmin again blows down the long axis of the tooth.
The intra-coronal restoration is seated with 2 mm of resin cement placed onto the TSF. It is rocked buccal-lingual with finger pressure, holding it on the occlusal surface. A curing light is used to tack the cement on the facial and lingual.
The excess cement is picked off using an appropriate hand instrument. This is done to insure the preparation is seated properly at the margins. Proper seating prevents future marginal leakage.
After the excess cement is removed, the restoration is cured facially and lingually for the appropriate manufacturer time.
The next step is to use a disc on a mandrel to smooth the margins. The interproximal areas are checked with a finishing strip and then flossed.
Finally, Dr. Adams polishes using a product of her choice, such as Caulk Prisma Gloss.
A final check of the intra-coronal onlay is done before showing Richard. Both Dr. Adams and Richard are pleased with the final outcome.
Jasmin follows up with a review of post-operative care, completes the chart entry, and escorts Richard to the front to finish the business portion of the appointment and set up his next re-care appointment.

Conclusion

Unit 4 study materials are now complete.
The dental procedures for an intra-coronal restoration should now be understood.
Before completing the self-test, ensure that all in-text questions are answered.
All 14 practice exercises should be completed before attempting the self-test.
Discuss any difficulties with your dentist for full understanding of the procedures.
The self-test checks your understanding of Unit 4 material, including readings, and gives practice answering final examination questions.
Restudy any areas of difficulty or errors after marking the self-test.
Thoroughly understand problem areas before writing the assignment and the final examination.

1.4. Self Test

Go to Quiz

1.5. Appendix

Direct Fabrication of an Intra-coronal Provisional Onlay Using a Final Impression Material for the Matrix

Armamentarium

Quadrant impression
- Cartridge of impression material
- Extruder gun, mixing tip
- Quadrant impression tray
Bis-acryl material
Mixing containers and spatula
Lubricant/separating medium
Variety of trimming sandpaper disks and round acrylic burs
Handpiece and mandrels
Articulating paper
Pencil
Cotton rolls and pellets, cotton pliers, and scissors
Spoon excavator, discoid cleoid
Explorer, mouth mirror
Floss
Lathe, rag wheel, and flour of pumice
Shade guide

Procedural Steps

Take the impression. Rinse and gently dry the impression.
Trim excess material to assist with the reseating of the impression when the restoration is fabricated.
Set out the provisional material ready for use along with the manufacturer’s directions. Select and record the shade.
Isolate the prepared tooth in the impression by placing a piece of moistened cotton roll on either side of the prepared tooth depression. The dentist has prepared the tooth for a MODL onlay, and the prosthodontic assistant now fabricates the provisional.
Isolate the prepared tooth with cotton rolls and thoroughly dry the area.
Lubricate the prepared tooth and teeth adjacent to the preparation. Use a cotton pellet to ensure that the proximal areas are covered.
Explain to the patient what you are about to do, mentioning the taste and odor that she or he might notice.
Mix the provisional material according to the manufacturer’s directions and pour it into the matrix, filling the depression of the prepared tooth. Remove the pieces of cotton roll.
Seat the acrylic-filled impression in the patient’s mouth.
Time the set according to the manufacturer’s directions.
After the recommended time has passed, remove the impression. The provisional may stay on the preparation, or it may come out with the impression. Using a spoon excavator or other hand instrument, gently remove the provisional from the tooth or the impression.
Place the provisional in a bowl of warm water to continue the set.
Thoroughly rinse the patient’s mouth. Place the patient in an upright position and allow him or her to take a break.
Once the provisional material has totally set, remove the provisional from the water and dry it thoroughly.
Using a pencil, mark the contact points and the margin on the provisional.
Starting with a disk, trim any excess away from the margin.
Switch to finer disks as the trimming gets closer to the marginal area. Avoid trimming the contact points.
Tip the patient back again and dry and isolate the preparation.
Try the trimmed provisional in the mouth.
Check the marginal fit using the explorer and then adjust the provisional as necessary.
Check the contacts by passing floss through them, and adjust as necessary.
Using articulating ribbon, check the occlusal contacts and adjust as necessary. Note: any adjustments to the marginal fit or the occlusal contact must be done outside the mouth.
Once satisfied with the fit, shape and function of the provisional, have the dentist check the provisional before removing it for polishing.
Using a rag wheel and pumice, polish the provisional. Avoid the margins and the contact areas.
Disinfect the provisional if required. The provisional crown is now ready for cementation.

Cementation of a Provisional Restoration

Armamentarium

Completed provisional
Petroleum jelly
Provisional cement, mixing surface, and spatula
Desensitizing agent or disinfectant agent
Cement application instrument
Cotton rolls and pellets, cotton pliers
Half Hollenback
Explorer, mouth mirror
Dental floss

1.6. Copyright

First edition published by Open College for the Province of British Columbia Ministry of Education, Skills and Training and the Centre for Curriculum, Transfer and Technology, 1997.
Second edition revisions by Catherine Baranow, Okanagan College, 2013.
Third edition revisions by Lorna McFadden, Okanagan College 2024
This material is owned by the Government of British Columbia and is licensed under a Creative Commons Attribution---Share Alike 4.0 International license.