Occlusal Adjustment
On this page
Direct answer
Occlusal adjustment — coronoplasty, selective grinding — removes the interferences that displace the mandible or overload individual teeth, converting a traumatic occlusion into a stable, mutually protected one, and in periodontics it is an adjunct delivered only after inflammation is controlled. The craft rests on definitions: a premature contact occurs before full intercuspation in the retruded contact position, a deflective contact displaces the mandible from centric relation into maximal intercuspation, and laterotrusive and protrusive interferences are eliminated so the anterior teeth guide the excursions while posterior teeth disocclude. What the grinding actually follows is the BULL rule — adjust the Buccal cusps of Upper teeth and the Lingual cusps of Lower teeth, the non-supporting cusps, so the supporting stamp cusps that carry the vertical load are preserved.
What you must remember
- BULL rule: grind buccal cusps of maxillary teeth and lingual cusps of mandibular teeth — non-supporting cusps — protecting the supporting (stamp) cusps: palatal of upper, buccal of lower.
- Centric prematurities are corrected first, then working and non-working side interferences, then protrusive interferences; each adjustment is re-marked before the next cut.
- The evidence hierarchy on trauma from occlusion (Glickman's concept, tested by Lindhe and colleagues): trauma alone does not initiate periodontitis or cause attachment loss in a healthy periodontium, but combined with plaque inflammation it can alter the pathway and speed of destruction — jiggling forces on an inflamed periodontium widen the periodontal ligament and accelerate bone loss.
- Primary occlusal trauma: excessive force on a healthy attachment; secondary: ordinary force on an attachment already reduced by disease — mobile tooth with widened ligament space.
- Splint therapy precedes irreversible grinding: a flat-plane occlusal splint worn for a period deprogrammes musculature and reveals whether the interference is structural or muscle-enforced.
- Freeway space, the interocclusal clearance between rest and occlusion, is 2-4 mm; equilibration must never consume it.
- Systematic reviews find occlusal adjustment alone does not treat periodontitis — it is adjunctive, and sequence demands phase I therapy first, with mobility often improving as inflammation resolves.
- Contraindications: bruxism unaddressed (grinding does not stop the habit), acute temporomandibular disorders, and gross skeletal or dental discrepancies better served by orthodontics, restorative or surgical correction.
An equilibration walkthrough
A 45-year-old with treated stage III periodontitis has a stable dentition except the lower right first molar: grade II mobility, widened ligament space, and a deflective contact that slides the mandible forward and left on closure. Step one is timing — inflammation is already controlled and the patient has completed cause-related therapy, so occlusal therapy is now legitimate. Step two is diagnosis with a splint: a full-arch flat-plane splint for two to three weeks removes the muscle engram and lets the mandible find its reproducible retruded contact position; the pretreatment slide often shrinks or disappears, changing the plan. Step three, marking: bilateral articulating papers in the retruded path of closure identify the first prematurity — here the mesial-lingual cusp of the upper first molar striking early. Step four, the adjustment itself follows BULL: the interfering buccal cusp of the upper molar is reduced, never the supporting palatal cusp, and the mark is re-tested rather than deepened blindly. Step five, excursions: non-working interferences on the balancing side are removed, working-side guidance confirmed on canines and premolars, protrusive guidance handed to the anteriors. Step six, polish with fine stones and fluoride paste, and review at two to four weeks — the hypermobility after adjustment is often transient, and mobility may downgrade as the ligament remodels.
How the exam frames it
The celebrated viva question is "Does traumatic occlusion cause periodontitis?" and the disciplined answer has three clauses: no, trauma alone does not initiate inflammatory periodontal destruction; yes, trauma superimposed on plaque-induced inflammation can change the pattern and rate of breakdown; and treatment of the inflammation is primary, with occlusal correction adjunctive. Examiners then trap the eager candidate who adjusts mobile teeth at presentation: mobility falls measurably after scaling alone in many teeth, so premature equilibration removes enamel that phase I therapy alone would have spared. A final favourite is the BULL acronym expanded correctly — buccal cusps of upper, lingual cusps of lower — a mark routinely given away by half-remembered answers.
Frequently asked questions
Does occlusal trauma initiate periodontitis?
No — animal and human evidence shows trauma alone does not cause attachment loss in a healthy periodontium, but combined with plaque-induced inflammation it can accelerate and redirect destruction.
What does the BULL rule direct?
Grinding is confined to the buccal cusps of upper teeth and the lingual cusps of lower teeth — the non-supporting cusps — so the load-bearing stamp cusps are preserved.
Why is splint therapy done before irreversible grinding?
A flat-plane splint deprogrammes muscle-induced occlusal positions and reveals the structural interference in a reproducible centric relation, preventing unnecessary enamel removal.
Distinguish primary from secondary occlusal trauma.
Primary trauma is excessive force on a healthy periodontium; secondary trauma is normal or excessive force on an attachment already reduced by periodontal disease.