Restorations and periodontal considerations

Question 1

List the 3 different types of restorative margin placements

Answer 1

• Supragingival
• Equigingival
• Subgingival

Question 2

Discuss the 3 different types of restorative margin placements in terms of effects on the periodontium and finishing of restorations.

Answer 2

Supragingival:
• Least impact on periodontium
• Newer more translucent materials, adhesives and resins can be placed in aesthetic areas with little impact on the periodontium
• Finishing is easy

Equigingival:
• Margins are at (equal to) margins of the gingiva
• As result of newer materials, periodontium is not significantly affected
• Finishing easier than subgingival

Subgingival:
• Margins are not visible clinically
• Margins are also not accessible for finishing procedures
• However, when a restoration is placed too far below the gingiva, impingement of the gingival attachment and subsequent violation of biologic width occurs

Question 3

For subgingival restorations, provide three reasons why they are placed beneath gingival tissue

Answer 3

• Adequate resistance and retentive form in the prep
• For significant contour alterations due to caries or other tooth deficiencies
• To mask tooth-restoration interface

Question 4

Define:
• Biologic width
• Biologic zone
• Dentogingival complex

Answer 4

Biological width:
· The distance from the base of the sulcus or pocket to the alveolar bone (approx 2.0mm)

Biological zone:
· Refers to the connective tissue attachment, junctional epithelium and sulcus apical to the restored margin

Dentogingival complex:
· The measurement from the crest of the alveolar bone to the gingival margin
· It is the interface between the tooth and gingiva, including the epithelial attachments and connective tissue attachment of the gingiva

Question 5

State the depth at which it is considered safe to place restorative margins subgingivally and explain how this is determined.

Answer 5

The apical extent of the restorative margin should be a minimum of 2.5mm away from the alveolar crest

Determined:
· Technique called sounding: place probe under pressure into sulcus until you touch bone. Since you need to be 2.5 mm away from bone, minus 2.5 mm from the number you get.

Other ways:
· Probing depths can be used to predict how deep the restoration margins can be placed ‘safely’:
· Shallow sulcus depths (1.0 -1.5mm): margins should not be more than 0.5mm
· Deeper sulcus depths: margins can be placed further below gingival crest

However, the deeper the sulcus, the more likely the risk of recession

Question 6

Identify the two potential periodontal responses to restorative margins that violate the biologic width

Answer 6

· Bone loss

· Gingival recession

Question 7

Discuss how marginal fit can affect the periodontal response

Answer 7

• Level of gingival inflammation is directly related to margin fit
• Margins that are significantly ‘open’ (voids/ deficiencies) are more capable of harboring plaque biofilm
• Margins that impinge gingival tissue can cause recession (excess)

Question 8

Discuss how contour can affect the periodontal response

Answer 8

• Contour of restorations can affect access for oral hygiene, space for interdental papillae and food impaction
• Ideal contour allows for good plaque removal and good aesthetics
• Over-contoured restorations (E.g. ‘bulky’ crowns) provides areas for plaque to accumulate, leading to inflammation and make it impossible to clean interproximally

Question 9

Discuss how sensitivity to dental materials can affect the periodontal response

Answer 9

· Reports of gingival inflammation related to use of non-precious alloys in restorations like nickel)
· Inflammatory responses to precious metals are rare

Question 10

Discuss interproximal embrasures in terms of restorations and periodontal health

Answer 10

• Embrasures should not be excessive (too large) as the extra space serves as a ‘food trap’

Embrasure spaces created by restorations should:
• Allow gingival papillae to fill the space without impingement
• Papillary height should be maintained (4.5 to 5.0mm above the interproximal bone)
• Ideally, papilla will have pointed form

Question 11

Discuss occlusal considerations in terms of restorations and periodontal health

Answer 11

• Occlusal trauma can serve as risk factor for periodontal disease
• Understanding and creating the create occlusion is vital in restorative dentistry

Question 12

Discuss pontic considerations in terms of restorations and periodontal health

(Pontic is the part of the bridge that rests on the gingiva)

Answer 12

• Pontic should provide an occlusal surface to allow for normal mastication, while not overloading abutment teeth
• Pontic surface should not be rough or else it will accumulate plaque
• The pontic should be shaped appropriate to prevent accumulation of food debris and allow ease of their removal