12.4 Iatrogenic Factors, Occlusal Trauma and Multidisciplinary Periodontal Care
Key Takeaways
Overhanging and subgingival restoration margins, overcontoured crowns, open contacts and poorly designed partial dentures retain plaque and are common iatrogenic causes of localized periodontal breakdown.
Primary occlusal trauma is injury from excessive forces on a normal periodontium; secondary occlusal trauma is injury from normal or excessive forces on a reduced periodontium.
Occlusal trauma does not initiate periodontitis, but in the presence of plaque-induced inflammation it may accelerate attachment loss, so inflammation is controlled first and occlusal therapy follows.
Comprehensive periodontal care follows a systemic phase, Phase I cause-related therapy, re-evaluation at about 4-8 weeks, Phase II surgery when needed, Phase III restorative care and Phase IV supportive maintenance.
Definitive restorative margins are placed only after the gingiva has stabilized following periodontal surgery, commonly at least 6 weeks posteriorly and longer (often several months) in the esthetic zone.
Two periodontal blueprint subsections, iatrogenic factors and multidisciplinary care and referral, test whether the general dentist recognizes the damage dentistry itself can do and coordinates care with other disciplines.
Iatrogenic Risks to the Periodontium
| Iatrogenic factor | Mechanism | Prevention or correction |
|---|---|---|
| Overhanging margins | Plaque-retentive ledge; pathogenic flora shift | Remove with finishing strips, fine diamonds or reciprocating files, or replace the restoration |
| Subgingival margins | Plaque at margin, biologic width (supracrestal attachment) violation | Keep margins supragingival when possible; crown lengthening if needed |
| Overcontoured crowns | Excess facial and lingual bulge traps plaque | Reproduce natural heights of contour; flat emergence profile |
| Open contacts | Food impaction, papilla inflammation | Restore tight contacts with correct position |
| Rough or poorly finished surfaces | Plaque accumulation | Finish and polish restorations |
| Poor RPD design | Gingival coverage, no rests, tissue-borne loading | Rests on abutments, relief over gingiva, open design, hygiene |
| Orthodontic forces | Labial movement through thin bone causes dehiscence and recession; tipping of plaque-covered teeth creates infrabony defects | Control inflammation first, light forces, keep roots within the alveolus |
| Surgical and chemical trauma | Flap damage, caustic agents, cord trauma | Gentle technique |
| Faulty tooth brushing | Abrasion and recession | Instruction in atraumatic technique |
Remember that removing an overhang during Phase I therapy often produces dramatic resolution of a localized pocket.
Trauma From Occlusion
| Type | Definition | Example |
|---|---|---|
| Primary occlusal trauma | Excessive occlusal forces on a periodontium with normal support | A high crown on a healthy tooth causing mobility and pain |
| Secondary occlusal trauma | Normal or excessive forces on a reduced periodontium | A tooth with 50% bone loss that drifts and becomes mobile under normal chewing |
Signs include increasing mobility, fremitus, pain on chewing, widened periodontal ligament space, thickened lamina dura and root resorption. Classic research (Glickman's co-destruction concept versus Waerhaug's view, and animal studies by Lindhe and colleagues) shows that occlusal trauma does not cause periodontitis on its own, but jiggling forces combined with plaque-induced inflammation can accelerate attachment loss. Management:
- Control inflammation first (cause-related therapy).
- Occlusal adjustment to remove prematurities and interferences.
- Splinting when mobility is increasing or interferes with function or comfort.
- Occlusal guard for parafunction.
The Phased Treatment Plan
| Phase | Content |
|---|---|
| Systemic phase | Medical history, risk factors, smoking cessation, glycemic control, antibiotic prophylaxis where required |
| Phase I (cause-related) | Oral hygiene instruction, supra- and subgingival instrumentation, removal of overhangs and plaque-retentive factors, caries control, extraction of hopeless teeth, provisional restorations |
| Re-evaluation | About 4-8 weeks after Phase I: probing, bleeding, plaque scores |
| Phase II (surgical) | Access flaps, regenerative or resective surgery, mucogingival procedures, implants |
| Phase III (restorative) | Definitive restorations and prostheses once the periodontium is stable |
| Phase IV (supportive) | Maintenance recall, usually about every 3 months initially |
Timing of definitive restorations: the gingival margin continues to move after surgery. Final margins are generally placed after the tissue has stabilized, commonly at least about 6 weeks after crown lengthening in non-esthetic areas and longer (often several months) in the esthetic zone, with provisional restorations in the meantime.
Restoration Design Decisions That Protect the Periodontium
| Clinical decision | Periodontally favorable choice |
|---|---|
| Margin location | Supragingival or equigingival whenever esthetics and retention allow |
| Margin that would invade the supracrestal attachment | Crown lengthening or orthodontic extrusion first |
| Emergence profile | Straight or flat, not bulbous |
| Furcation areas | Open embrasures that admit interdental brushes; fluting of crowns over furcations |
| Pontics | Modified ridge lap or sanitary designs with convex, polished tissue surfaces |
| Splinted crowns | Only when necessary; leave room for interdental cleaning |
| Removable prostheses | Rests on abutments, gingival relief, minimal coverage of marginal gingiva |
Multidisciplinary Care
- Perio-restorative: design restorations with supragingival margins, cleansable embrasures and pontics, and appropriate contours; respect the supracrestal tissue attachment.
- Perio-orthodontic: treat periodontitis before orthodontics; use light forces in adults with reduced support; orthodontic extrusion can level bone defects or prepare implant sites; long-term retention (bonded retainers) is often needed.
- Perio-endodontic: evaluate pulp vitality in teeth with deep pockets; treat the endodontic component first in combined lesions (see the endo-perio section).
- Perio-prosthodontic and implant: treat periodontitis before implant placement, because previous periodontitis increases peri-implantitis risk.
- Medical collaboration: diabetes control, medication-induced enlargement, anticoagulant management, and smoking cessation programs.
When to Refer to a Periodontist
Referral is generally appropriate for Stage III or IV periodontitis, Grade C progression, disease that progresses despite good Phase I therapy, furcation involvement needing surgery, deep vertical defects suitable for regeneration, mucogingival problems needing grafts, patients with systemic conditions complicating care, and complex implant cases. A referral letter should include history, charting, radiographs, diagnosis and the treatment already provided, and the general dentist continues to coordinate maintenance and restorative care.
Exam Traps
- Splinting mobile teeth without first controlling inflammation does not halt periodontitis.
- An overhang on a restoration next to an isolated deep pocket should be removed during Phase I, not after surgery.
- Secondary occlusal trauma refers to the reduced periodontium, regardless of whether forces are normal or excessive.
A patient with generalized Stage III periodontitis and 50% bone loss has increasing mobility of tooth 31 under normal chewing forces. How is this classified?
Secondary occlusal trauma, because normal forces act on a reduced periodontium
Necrotizing periodontitis, because mobility is its most specific diagnostic sign
Primary occlusal trauma, because any mobility means the occlusal forces are excessive
Physiological mobility, because the periodontal ligament always allows 2 mm of movement
Tooth 36 has an isolated 6 mm pocket on its mesial surface, directly next to a large amalgam overhang. What should be done during Phase I therapy?
Wait for periodontal surgery, because overhangs are corrected only in Phase II
Extract tooth 36, because overhangs cause irreversible bone loss in every case
Remove or correct the overhang together with subgingival instrumentation
Prescribe systemic antibiotics, because overhangs harbor resistant bacteria
Crown lengthening was performed on tooth 11 to expose a fracture before a new crown. When is it generally appropriate to make the final crown impression?
Exactly 7 days after surgery when the sutures are removed, regardless of healing
Never, because crown lengthening permanently contraindicates a crown on the same tooth
On the same day as surgery so the margin can be placed before the tissue swells
After the gingival margin has stabilized, usually several months in the esthetic zone
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