Post on 17-Dec-2015
Provisional Restorations
Dr. Arwa H.AL-Musa
211 RDS
Definition
A dental prosthesis worn following the tooth preparation for a various periods of time, which maintains esthetics, provides articulating surfaces & protects hard & soft tissues prior the delivery of the permanent dental prosthesis (temporary, interim)
Requirements
1- Protect the remaining tooth structure from chemical, thermal & biological insult.
2- Pulpal protection: a- Thermal insulation b- Well adapted margins to prevent leakage of saliva
3- provide for esthetics, phonetics and masticatory function
4- Maintain the health of the periodontium, should have no overhangs or impinging margins
5- Diagnosis and patient evaluation.
Types of Provisional Restorations
1- Zinc oxide eugenol (IRM).2- Prefabricated provisional restorations.3- Custom made provisional restorations.
Zinc oxide Eugenol
Zinc oxide eugenol (IRM) :
Polymer-reinforced zinc oxide eugenol interim restorative material used for small intracoronal preparations e.g. inlays
Disadvantages:
a- doesn’t protect the remaining tooth structure b- can only be used as an intracoronal restoration
Prefabricated ProvisionalRestorations
Definition: ready-made restoration that needs minimal adjustment
e.g polycarbonate crowns, metal crowns
Polycarbonate Crowns
Tooth colored, supplied in incisor, canine and premolar shapes
Adv.
• mimic the natural tooth color
Dis.
• Available only in one shade
Prefabricated Metal Crowns
• Suitable for posterior teeth
• Needs some modifications for
proper adaptation
Steps of fabrication
1- after tooth preparation, select the proper crown size from the mold
A- polycarbonate crown:
adjust the length of the crown by trimming the excess gingival part using carborundum stone or acrylic bur
2- Adjustment:
A- Metal crown:
length is adjusted by removing gingival excess by scissors, then smoothened and contoured using plires.
2- Adjustment:
3- apply separating medium on the prepared tooth ( petroleum jelly)
4- mix autopolymerizing acrylic resin in a dappen dish
5- Fill the crown with acrylic resin then seat it correctly on the tooth and remove the excess resin around the margins.
6- check the occlusion using articulating paper
7- remove the high spots then finish it and polish it using white stone burs and rubber points.
8- cement it using temporary cement.
Custom Made Provisional
Made to fit specifically the patient’s prepared tooth
Techniques for FabricatingCustom Made Provisional
1- Direct
2- indirect
Made directly inside the patient’s mouth
Direct
Made outside the patient’s mouth
Indirect:
Steps for fabricatingCustom made provisional
1- Direct technique
1- Take a preoperative impression ( before the tooth preparation).
2- After tooth preparation, apply a light film of petroleum jelly ( separating medium).
3- Mix the self-cure acrylic resin in a dappen dish.
4- Fill the impression at the area of the prepared tooth with acrylic resin.
5- Place the impression on the prepared tooth correctly.
6- Take it in and out until the material sets.
7- Remove the provisional rest.
8- Then finish it and polish it.
9- Check the occlusion then cement it using temporary cement e.g. temp bond cement.
Wake Up!!
1- Indirect technique
1- Take a preoperative impression.
2- After tooth preparation take a postoperative impression and pour it to get a postoperative cast.
3- Apply a separating medium on the cast then mix some acrylic resin in a dappen dish.
4- Fill the preoperative impression at the area of the prepared tooth with acrylic resin.
5- Seat the postoperative cast into the preoperative impression.
6- After the resin has set remove the provisional and finish it an polish it.
7- After the resin has set remove the provisional and finish it an polish it.
8- Try it in the patient mouth and check the occlusion
9- Cement it using temporary cement material.
It’s almost over
Adv.
• Faster• Fewer steps
Dis.• Slightly inferior in
marginal fit• Might lock in the
undercuts of the prepared tooth
• Thermal &chemical insult to the tooth
Direct
Adv.
• Better marginal fit• Avoids the possibility of
locking on the tooth• No thermal or chemical
insult to the tooth or soft tissue
Dis.
• Takes more time• Has more steps
Indirect
Materials Used for custom made provisional restorations
1- polymethyl methacrylate
Adv.
• High strength• color stability• wear resistance
Dis.• Tissue damage
from the monomer & exothermic heat reaction
• Polymerization shrinkage
2- polyethyl methacrylate
Adv.
•Less exothermic heat reaction•Less polymerization shrinkage
Dis.
• Less color stability• Less wear
resistance
3- Filled Resins:
Adv.
• Most esthetic• Accurate fit
Dis.
• Brittle• subject to bulk
fracture