gtc 6 - finishing (ppsg lectures)

7/28/2019 GTC 6 - FINISHING (Ppsg Lectures)

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FIXED PROSTHODONTICS

DR. ERWAN SUGIATNO

DR HARYO M.DIPOYONO

PUSAT PENGAJIAN SAINS PERGIGIAN

UNIVERSITI SAINS MALAYSIA


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FINISHING & CEMENTATION

The surface of the casting that is retrievedfrom investment is too rough for use in themouth

Five preparatory procedures need to beperformed on any type of cementedrestoration after it has been fabricated inthe laboratory : preliminary finishing, try-in

and adjustment, pre-cementationpolishing, cementation, and post-cementation finishing


3/20

Preliminary Finishing

To minimize the expenditure of valuable

chair time, preliminary adjustment usingthe die and master cast should be

completed on the internal and external

surfaces of the restoration prior to the

cementation appointment


4/20

Armamentarium

1. High-speed handpiece 2. Straight handpiece

3. Separating disc on mandrel

4. No.2F Craytex disc on mandrel

5. 5/8-inch Burlew wheel on mandrel

6. Sulci disc on small-head mandrel

7. No. 0 budfinishing bur

8. No. 330 friction-grip bur 9. Articulating paper

10. Green stone


5/20

Remove any small nodules or bubbles with ano. 330 bur in a high-speed handpiece

Use a separating disc to cut the sprues from thecasting

Use a coarse rubber disc to smooth away theroughness left by the separating disc

Use the finer Burlew or Gold Lustre Blue disc in asimilar manner after the coarse disc

The axial surface should be finished to themargin, the disc should be rotated parallel withthe margin, rather than perpendicular to it.


6/20

Remove nodules used no. 330 burSprue is removed with a separating disc.

Axial surface are smoothed with a Burlew wheel (A). The

wheel should be turned parallel with the margin (B).


7/20

Use a no. 0 bud finishing bur to smooth

out the grooves on the occlusal surface

Smooth the cusp ridges and blend them

into the groove on the occlusal surface with

a small rubber sulci disc.


8/20

Grooves are finished with a small bud finishing bur.

Cusp ridges are finished with a small sulci disc.


9/20

Try-in and Adjustment

If you are careful and gentle, the try-in procedurecan be accomplish on many patients withoutadministering an anesthetic.

Cementation should be postponed if the patientreports that the tooth has been hypersensitiveunder provisional crown.

Make sure the provisional restoration is not

hyperocclusion and that it covers all preparedtooth surfaces.

Recement it for several days.


10/20

Adjustment of Proximal Contacts

The proximal contacts of a restoration must be

neither too tight nor too light.

If they are too tight, they will interfere with

correct seating of the restoration, producediscomfort, and make it difficult for the patient to

floss.

If they are too light, they will allow impaction ofstrands of food, which is deleterious to the

gingiva and annoying to the patient.


11/20

A frequent cause for failure of restoration to seat

completely is an overcontoured proximal surface.Hold the restoration firmly in place and test both

proximal contacts with waxed floss.

If both proximal contacts feel too tight, adjust

only the tighter contact first.

Care must be taken not to remove too much

material from the contact area.

If the proximal contact is open or too light, thismust be corrected by adding solder before

cementation.


12/20

Proximal contacts are tested with dental floss.


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Marginal Adaptation

After the proximal contacts have been

corrected, seat the restoration and examine

the margins closely.

An acceptable margin is not overextended,

underextended, too thick, or open.


14/20

Types of defective margins : overextended (A),

underextended (B), thick (C), and open (D).


15/20

Margin Finishing

Two types of margins need to be considered

Subgingival margins can be burnished on the

die with a beavertail burnisher or fine stone

Supragingival margins of inlays, onlays, and

partial veneer crowns can be finished on the

tooth.


16/20

A burnisher, such as a dull Spratley knife, can

be used to press the margins against the tooth

surface

The white stone should always rotate from

casting to tooth surface, under heavy pressure

and at low speed.


17/20

All accessible margins are burnished intraorally with a

smooth, dull instrument.

Margins are finished with a white stone rotating fromalloy to tooth.


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Occlusal Adjustment

Insert the restoration and see, if the patient can

still hold the shim between the same pair of

nearby teeth.

If not the crown is high in the intercuspal position.

If the patient can hold

shim stock on adjacent

teeth with the crown out,

but not with in it, the

crown is too high.


19/20

If the mandible shifts to the side where therestoration is located, the buccal incline of the

maxillary lingual cusp or the lingual incline of themandibular buccal cusp needs adjustment.

If the mandible shifts to the side away from therestoration, one of two deflective contacts requires

correction, there is a possibility of a heavy contactbetween the lingual incline of the maxilary buccalcusp and the buccal incline of the mandibular buccalcusp.

There may also be excessive contact between thelingual incline of the maxillary lingual cusp and thebuccal incline of the mandibular lingual cusp thatneeds correction.


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A premature contact on the buccal incline of the maxillary lingual cusp

produces a buccal shift of the mandible.

A premature contact on the lingual slope of the maxillary buccal cusp

produces a lingual shift of the mandible.A premature contact on the lingual incline of the maxillary lingual cusp

produces a lingual shift of the mandible.

gtc 6 - finishing (ppsg lectures)

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