Bonding, Cementation, and Finishing of Full Crowns: 5 Steps and 19 Key Points

1. Preliminary Preparation

 

(1) Inspect the Integrity of the Crown: Check for defects, sand holes, or shrinkage porosity.
(2) Confirm Complete Seating on the Model: The crown should contact the model only at the margins, with the internal surface having a gap of 30-40μm from the model surface.
(3) Adjust Proximal Contacts on the Model: Use thin articulating paper for precision.
(4) Adjust Occlusion on the Articulator: First, address premature contacts in centric occlusion, followed by premature contacts in eccentric occlusion.
(5) Preliminary Polishing and Cleaning: Polish the external surface, sandblast the internal surface, and clean thoroughly.

 

 

2. Intraoral Try-In and Adjustment

(1) Patient Inquiry: Ask if the affected tooth has experienced any abnormalities since the last treatment.
(2) Examination of the Affected Tooth: Perform a periodontal assessment and check the pulp status for vital teeth.
(3) Clean the Surface of the Affected Tooth: Ensure it is free from debris or contamination.
(4) Placement of the Prosthetic Crown: Position the crown carefully on the prepared tooth.

 

1. Theoretical Indicators

The gap between the inner surface of the prosthetic crown and the tooth surface should not exceed 50μm.

 

2. Reference Indicators

(1) The gingival margin of the prosthetic crown should reach the designed position.
(2) Occlusion should be generally appropriate.
(3) The crown should be stable after placement, with no rocking or movement.

 

3. Factors Hindering Crown Seating and Solutions

Factors Hindering Crown Seating	Solutions for Overcoming Crown Seating Issues
Undercut	Small problem require appropriate adjustment, while big peoblem require remaking
Sharp Line Angles	Appropriate Adjustment
Model Damage	Appropriate Adjustment
Casting Defects	Grinding and Removal
Tight Proximal Contacts	Adjustment
Gingival Impingement	Removing Overgrown Gingiva
Other Reasons	Process according to actual factors

 

(5) Adjustment Sequence After Crown Placement

1. Proximal Contact: Adjusted based on the placement of the artificial crown.
2. Retention
3. Marginal Adaptation: The gap between the crown margin and the cervical margin should be <50μm.

 

4. Occlusal Adjustment

1. Reference Point: A pair of teeth adjacent to the affected tooth, able to bite down on a 13μm thick layer of articulating paper.

 

2. Adjusting Centric Early Contact: Both sides of the teeth bite simultaneously. If the lower jaw shifts toward the side of the artificial crown, adjust the artificial crown on the upper jaw on the lingual-cuspal inclined surface

(A) On the lower jaw, adjust the buccal-cuspal inclined surface.

If the lower jaw shifts toward the opposite side of the artificial crown, adjust the artificial crown on the upper jaw on the buccal-cuspal inclined surface

(B) On the lower jaw, adjust the buccal-cuspal inclined surface.

The artificial crown on the upper jaw may also need adjustment on the lingual-lingual inclined surface

(C), and the artificial crown on the lower jaw may require adjustment on the lingual-buccal inclined surface.

 

3. Adjusting Non-working Side Early Contact: The early contact points on the upper jaw's lingual-cuspal inclined surface or the lower jaw's buccal-cuspal inclined surface should be eliminated.

 

 

4. Adjusting Working Side Early Contact: For canine-protected occlusion, remove the early contact points on the upper tooth's buccal-cuspal inclined surface and the lower tooth's buccal-cuspal inclined surface. For group function occlusion, retain these contact points and adjust them to align with the contact between the canines.

 

 

5. Adjusting Protrusive Early Contact:
Adjust the distal inclined surface of the cusp on the upper jaw's artificial crown, and adjust the mesial inclined surface of the cusp on the lower jaw's artificial crown. For anterior teeth, in centric occlusion, the anterior teeth should not contact. During protrusion, the anterior teeth should make contact.

 

 

(6) Contour: Meets physiological requirements and anatomical features.

(7) Esthetics: The position, shape, alignment, and color are coordinated with adjacent teeth and the overall dental arch.

 

 

3. Surface Treatment of the Restoration Before Cementation

 

Mechanical Polishing and Glazing

1. Metal Crowns:
Before cementation, polish the areas adjusted during the try-in according to the preliminary polishing sequence until they are consistent with the remaining surfaces. Then, use a wet abrasive wheel to polish, followed by a dry polishing wheel with polishing paste to achieve a high-gloss, mirror-like finish. Use ferric oxide polishing paste for gold alloys, and chromium oxide polishing paste for other metals.

2. Porcelain Crowns:
After smoothing the adjusted areas, apply glazing.

 

 

4. Cementation

1) Requirements for an Ideal Cementing Agent

1. Strong Bonding Strength

2. High Internal Strength

3. Insoluble in Saliva

4. Non-irritating to the Pulp

5. High Flowability, Easily Forms a Thin Film Between the Restoration and Prepared Tooth Surface

6. Simple to Use

7. Excess Cement Overflow After Cementation is Easy to Remove

8. Affordable Price

 

2) Properties of Different Cementing Agents

Cementing Agents	Properties
Zinc Phosphate Cement	High compressive strength, strong bonding strength, but it can be irritating to the pulp and is not suitable for vital teeth.
Polycarboxylate Cement	high tensile strength, low compressive strength, relatively high bonding strength, and no irritation to the pulp.
Glass Ionomer Cement, GIC	Antibacterial properties, low solubility, can release fluoride, and is suitable for individuals prone to cavities.
Resin Cement	High bonding strength, is insoluble in water, and is available in chemical curing, light curing, and dual curing forms.

 

5. Post-Cementation Treatment

1. Check the occlusion

 

2. Marginal polishing

Polish the crown margins with a rubber cup and pumice.

 

3) Oral hygiene education: Use dental floss to clean the mesial and distal surfaces of the crown, and schedule regular check-ups.