What do systematic reviews say?

Indirect restorations (crowns, fixed partial dentures, inlays/onlays/veneers) vs None (single-group incidence)

Periapical pathosis incidence among follow-up >5-10 years was 3.88% (subgroup analysis; not GRADE-rated).

• Incidence and influential factors in pulp necrosis and periapical pathosis following indirect restorations: a… 2023 All outcomes

  >5-10 years · University clinics and dental practices, multiple countries · Follow-up >5-10 years
  Proportion 3.88 [1.95, 6.45]
  1864 participants
  GRADE not reported
• Incidence and influential factors in pulp necrosis and periapical pathosis following indirect restorations: a… 2023 All outcomes

  >10 years · University clinics and dental practices, multiple countries · Follow-up >10 years
  Proportion 4.05 [0.89, 9.36]
  2656 participants
  GRADE not reported
• Incidence and influential factors in pulp necrosis and periapical pathosis following indirect restorations: a… 2023 All outcomes

  Follow-up ≤5 to >10 years · University clinics and dental practices, multiple countries · Fixed partial dentures (FPD)
  Proportion 4.59 [2.28, 7.64]
  9 studies · 2435 participants
  GRADE not reported

Gum chewing (sugar-free) vs Within-subject before/after comparison of soft gum vs hard gum (no no-gum control)

One small study found that chewing hard (but not soft) gum increased oral mucosal moisture.

• The effect of gum chewing on xerostomia and salivary flow rate in elderly and medically compromised subjects: a… 2023 All outcomes

  2-week chewing period (soft then hard gum, with 2-week wash-out) · Haemodialysis units, elderly / geriatric care, cancer and palliative care, and xerostomia / hyposalivation clinics (studies from multiple countries)
  Single study [22] (Nakagawa 2017): chewing hard gum significantly increased oral mucosal moisture whereas chewing soft gum did not.
  1 study · 12 participants
  GRADE not reported

Polyether impression material vs Polyvinyl siloxane impression material

The pooled incidence with polyether impression material was 4.02%.

• Incidence and influential factors in pulp necrosis and periapical pathosis following indirect restorations: a… 2023 All outcomes

  Polyether
  Proportion 4.02 [2.47, 5.92]
  2985 participants
  GRADE not reported
• Incidence and influential factors in pulp necrosis and periapical pathosis following indirect restorations: a… 2023 All outcomes

  Polyvinyl siloxane
  Proportion 3.17 [1.55, 5.34]
  636 participants
  GRADE not reported

Ceramic restoration material vs Porcelain-fused-to-metal restoration material

The pooled incidence with ceramic restorations was 5.59%.

• Incidence and influential factors in pulp necrosis and periapical pathosis following indirect restorations: a… 2023 All outcomes

  Ceramic
  Proportion 5.59 [2.89, 9.12]
  460 participants
  GRADE not reported

Pulp-status assessment method

The pooled incidence with radiographic assessment was 4.95%.

• Incidence and influential factors in pulp necrosis and periapical pathosis following indirect restorations: a… 2023 All outcomes

  Radiographic
  Proportion 4.95 [2.43, 8.29]
  5 studies · 1853 participants
  GRADE not reported
• Incidence and influential factors in pulp necrosis and periapical pathosis following indirect restorations: a… 2023 All outcomes

  Objective
  Proportion 5.66 [3.71, 7.99]
  24 studies · 6581 participants
  GRADE not reported

Zinc polycarboxylate cement

One study reported a 1.1% incidence with zinc polycarboxylate permanent cement.

• Incidence and influential factors in pulp necrosis and periapical pathosis following indirect restorations: a… 2023 All outcomes

  Zinc polycarboxylate
  Proportion 1.1
  1 study
  GRADE not reported

Intervention not reported

• Incidence and influential factors in pulp necrosis and periapical pathosis following indirect restorations: a… 2023 All outcomes

  Compound impression material
  Proportion 3.27
  1 study
  GRADE not reported

Gum chewing (sugar-free) vs No chewing gum

Gum chewing was linked with improved self-reported xerostomia / dry mouth in most studies (12 of 17 positive, 5 no effect); heterogeneous instruments precluded meta-analysis.

• The effect of gum chewing on xerostomia and salivary flow rate in elderly and medically compromised subjects: a… 2023 All outcomes

  Various (single session to 3 months) · Haemodialysis units, elderly / geriatric care, cancer and palliative care, and xerostomia / hyposalivation clinics (studies from multiple countries)
  Narrative vote-count: of 17 studies measuring self-reported xerostomia / dry mouth, 12 found a positive effect of gum chewing [18,19,21,23,24,25,26,27,30,31,38,40] and 5 detected no effect [17,29,33,34,37]. No study…
  17 studies
  GRADE not reported

Indirect restorations (crowns, fixed partial dentures, inlays/onlays/veneers) vs None (single-group incidence)

The pooled incidence with ≤ 5 years of follow-up was 3.53%.

• Incidence and influential factors in pulp necrosis and periapical pathosis following indirect restorations: a… 2023 All outcomes

  ≤ 5 years · ≤ 5 years
  Proportion 3.53 [2.10, 5.31]
  5532 participants
  Low

Preterm birth (<37 weeks gestation) vs Full-term birth (37 weeks or more gestation)

In children aged 3 years or younger, preterm birth was not associated with early childhood caries (OR 0.90, 95% CI 0.59 to 1.37); certainty not graded.

• Relationship between preterm, low birth weight and early childhood caries: a meta-analysis of the case-control and… 2020 All outcomes

  Community/epidemiological studies of preschool children (multiple countries) · Children aged 3 years or younger
  OR 0.90 [0.59, 1.37]
  2 studies
  GRADE not reported
• Relationship between preterm, low birth weight and early childhood caries: a meta-analysis of the case-control and… 2020 All outcomes

  Community/epidemiological studies of preschool children (multiple countries) · Overall
  OR 1.59 [1.36, 1.87]
  16 studies · 21279 participants
  GRADE not reported