1.30 Jo_Periodontal wound healing Flashcards
What are the 4 stages of flap healing (according to Wilderman 1965)?
Wilderman & Wentz 1965
Flap pedicle healing goes through four stages:
1. Adaptation - Day 0-4
2. Proliferation - Day 4-21
3. Attachment - Day 21-28
4. Maturation
What are the three types of wound healing (primary, secondary, tertiary intention)?
Primary: Primary closure of the wound.
Secondary: Wound edges are not approximated, so healing occurs through formation of granulation tissue
Tertiary: Also known as “delayed primary closure”. In heavily infected or contaminated wounds, the wound is left to heal on its own.
What is the timeline of wound healing? Describe the timeline.
Hemostasis: immediately, to 1 day after injury. Formation of a platelet plug and stable fibrin clot.
Inflammatory: 2-4 days. Neutrophils and monocytes migrate, phagocytosis occurs, inflammatory cytokines are released
Proliferative: 4-21 days. Macrophages release growth factors for fibroblast proliferation. Fibroblasts produce abundant Type III collagen. At 1 week, fibroblasts differentiate into myofibroblasts (producing alpha-smooth muscle actin) and cause wound contraction.
Maturation / remodeling: 21days - 1 month+. Maturation of the collagen occurs (fibroblasts replace type III with type I collagen). Collagen cross-linking and VitC-dependent hydroxylation occurs.
How long does it take for the junctional epithelium to reform after surgery?
Stahl 1971: Pocket epithelium forms 1 week after curettage & root planing. After 8 weeks, SRP sites showed similar inflammatory Infiltrates compared to control sites.
Waerhaug 1978: Reformation of dento-epithelium junction (JE) occurs within 2 weeks post-SRP where subgingival plaque and calculus has been removed. If some subgingival plaque is left after SRP, the remnants cause rapid reformation of plaque (apical growth with a rate of 2μm/day) within pocket and loss of attachment.
Is the long JE more susceptible to periodontal disease?
Magnusson ‘83
Monkey study
Ligature-induced LJE responded similarly to plaque accumulation
compared to normal JE in an animal model.
Histologic inflammatory infiltrates induced by plaque did not extend
deeper into periodontium in LJE, indicating that a LJE has proper barrier
function against plaque infection, and is not inferior to that of dentogingival epithelium of normal length.
Beaumont & O’Leary ‘84:
Beagle dog study
LJE is resistant to plaque accumulation and disease progression similar to normal periodontium.
* Location of the apical cells of the attachment epithelium did not show
significant changes in both long and normal JE groups.
Who described the healing of the soft tissues after gingivectomy? (and proved that CT healing completes at 4-6 weeks?)
Engler & Ramfjord ‘66
2 hours - Blood clot formation and neutrophil migration.
13 hours - PMN band covers the wound.
1 day - new CT cells appear beneath the PMN poly-band. Peak DNA synthesis within 2 mm from the wound margins.
2 days - PMN’s are replaced by lymphocytes.
3 days - endothelial cells & fibroblasts are concentrated beneath the polyband (0.3 - 0.5 mm)
7 days - wound is fully epithelialized. Sulcus epithelialization begins.
9 days - the most osteoclastic activity is observed at the alveolar crest.
2 wks - no more osteoclastic activity seen. FGM is fully formed. Keratinization & collagen bundles increase.
35 days- The marginal and sulcular gingival surfaces are completely epithelialized. The new CT is indistinguishable from the old CT. Inflammatory cells are mostly lymphocytes and plasma cells.
What is the healing after mod Widman flap? (created by Ramfjord & Nissle ‘74)
Caton & Nyman ‘80:
Rhesus monkey study
Mod Widman heals by a long JE.
How strong is a full thickness flap?
Hiatt ‘68
16 Mongrel dogs
Silk sutures were used to determine flap tensile strength.
2-3 days: 225g
7 days: 340g
14 days: 1700 g
For a pedicle flap, what is the minimum length-to-width ratio of the flap?
Mormann ‘77
Blood supply of different flap designs was evaluated (horizontal, internal bevel, vertical incision, pedicle flap ± tension) by fluorescin angiography 24 hours post-surgery.
* The flap should have a broad base, length to width ratio = 2:1, minimal tension. A partial thickness flap should be not too thin to have more blood vessels in the lamina propria and more resistance to trauma.
What is the bone loss after flap reflection?
Wood ‘72:
Human study
Alveolar bone loss after partial thickness flap elevation = 0.98 mm
* Alveolar bone loss after full-thickness elevation = 0.62mm
*Critique
o Used 1-mm measurement instrument with a stent faraway from bone
o Variability in thickness of C.T. layer in partial thickness flap. No baseline bone & soft tissue thickness before surgery.
Fickl ‘11:
Dog study
Alveolar bone loss after partial thickness flap elevation = 0.12 mm
* Alveolar bone loss after full-thickness flap elevation = 0.64 mm
*Critique: Dog has very thick gingival phenotype, very limited sample size (n=4)
Describe the Velasquez & Chan ‘23 article on when to use certain incisions.
4 common incision designs involving papilla and neighboring tissues:
o Tunneling – supply of SPA can be preserved
o Papilla base – endo advocated; facial horizontal incision made b/t line angles,
papilla not elevated, ITOA and transverse anastomosis arterioles can be
preserved
o Simple papilla preservation – use for GTR to aim for primary closure
o Traditional papilla incision – compromise microcirculation
- Flap design can affect the blood reperfusion and blood inflow in the early healing phase.
- Tissue recession and loss is in direct relation to flap elevation and microvasculature anastomosis disruption.
Describe the Wilderman ‘70 study on healing after osseous surgery.
Wilderman ‘70:
Over a period of 6 months, 1.2 mm of bone resorption is expected initially.
* However, after 18 months of observation, it showed that there was a **0.4 mm bone re-formation **(apposition).
* A net alveolar bone loss of 0.8 mm.
* 3-4 weeks have peak bone repair. At 6-mo there is immature bone, at 18-mo there is mature bone.
How long does it take for the mobility after osseous surgery to disappear?
Selipsky ‘76
Removing interproximal bone in osseous surgery may be responsible for increased mobility.
* The increased mobility returned to pre-surgical mobility status within 1 year.
What is the average bone loss in furcations, interradicular regions, and radicular areas after osseous surgery?
Moghaddas & Stahl ‘80
The average bone loss following osseous surgery by location:
o Interradicular 0.23 mm
o Radicular 0.55 mm
o Furcation 0.88 mm
Osseous surgery is healed by repair with crestal bone resorption.
How long should you wait after crown lengthening before placing the crown?
Bragger ‘92: 85% of the sites showed +/-1mm FGM change b/w 6 weeks to 6 months.
* Wait 6 months before final crown delivery
Pontoriero ‘01: Changes might occur even after 12 months with rebound, especially in patients with thick biotypes.
* Tissue rebounds 2.9mm when the mean bone reduction is 1 mm.
Deas ‘04: Tissue rebound after CL is not fully stabilized by 6 months.
* Tissue rebound of 1.33 mm if <1 mm from crest
* Tissue rebound of -0.16 mm if >4 mm from crest
The amount of tissue rebound seems related to the position of the flap relative to the alveolar crest at suturing.
