The Periodontal - Restorative Interface Flashcards
What relationship does gingival margin have with the crestal bone
Healthy gingival margin appears to maintain a predetermined relationship to underlying crestal bone
Biological width =
Biological width = summation of supra-crestal conn. tiss. attachment & junctional epithelium
BW approx. 2.0 - 3.0mm but variable
Dento-gingival complex
Suggested effects of violating the biologic width
Physical trauma & plaque retention may cause gingival inflammation
Crestal bone resorption & apical migration of dento-gingival complex to re-establish BW
Requirements of ideal restoration margin
Shape contributes to minimal marginal opening
Strength of material to resist distortion or fracture during function (CSA)
Good appearance
Convenient to prepare & record by dentist
Easy to locate on die & work with in lab
Contribute to maintenance of periodontal health
Location of restorations margins
1908 – Black’s sub-gingival extension for prevention
1970’s Sub-gingival margins challenged
Assoc. with increased incidence & severity of gingival & periodontal disease
Overhanging margins correlated with clinical & radiographic evidence of alveolar bone
Supra-gingival margins - why are they good?
Good access / visibility
Convenient to prepare / record impression
Simple to locate & work to in lab
Allows better evaluation of margins clinically
Easier for patients to clean (sub gingival margins are hard to clean)
Reasons for sub-gingival margins ?
Extension of dental caries
Sub-gingival fracture of teeth
Previous restoration extended sub-gingival
Mechanical retention (lack of crown height)
Strength (ferrule effect = 1.5mm)
Aesthetics
Crown lengthening procedures
Periodontal surgery
Gingivectomy/gingivoplasty
Apically repositioned flaps with bone removal
Orthodontic extrusion
If not enough height, - gingivectomy / gingivoplasty / crown lengthening surgery
Design/form of restoration margins ?
- Direct restorations
- Indirect restorations
Knife / feather edge
Bevel
Chamfer
Shoulder
Shoulder bevel
Fit & quality of margins - what causes them to be PRF?
Open margins
Overhangs (different types)
Micro-porosity
Surface roughness
Shrinkage
All margins are imperfect & collect plaque!
Insertion of direct restorations - how to decrease chance of overhangs
Accurately contoured & positioned matrix
Wedges
Gingival displacement around margins
Mechanical
Mechanical/chemical
Gingitage
Electrosurgey
Retraction cord
Electrosurgery
Restoration contours & Embrasures
Buccal & lingual contours
Emergence profile = tooth profile that emerges from the gingival sulcus
Greater convexity = more difficult to remove plaque
Flat or slightly concave desirable
Note furcation areas and shape accordingly
If emergence profile incorrect, then all other contours will be wrong’s,,.,k
Embrasure space
Embrasure form depends upon
Clinical crown height
Root proximity
Cervical contour
Root anatomy
Aesthetics
Embrasures
Contact areas in occlusal 1/3 & buccal
Sufficient tooth reduction critical
Embrasure space large enough to allow for normal papilla – avoid impingement of col
Embrasures
Contact areas in occlusal 1/3 & buccal
Sufficient tooth reduction critical
Embrasure space large enough to allow for normal papilla – avoid impingement of col
Traditional occlusal teachings
Forces directed along long axis
Minimize lateral forces
Contacts in ICP (intercuspal position) / RCP
Anterior & lateral guidance
Occlusal stability
Occlusion & periodontal disease
Trauma from occlusion = pathological alterations or adaptive changes which develop in the periodontium, as a result of excessive occlusal forces from premature contacts or parafunction
Primary & secondary occlusal trauma
Occlusion & periodontal disease -
What does Trauma in the presence of marginal periodontitis cause
Trauma in the presence of marginal periodontitis increases alveolar bone loss radiographically, BUT loss of connective tissue attachment is controversial
Occlusal therapy
May reduce occlusal load by occlusal adjustment of tooth during initial therapy
Can spread load by splinting teeth, (after initial therapy to reduce plaque related inflammation)
Occlusal therapy
May reduce occlusal load by occlusal adjustment of tooth during initial therapy
Can spread load by splinting teeth, (after initial therapy to reduce plaque related inflammation)
Splinting – suggested indications?
Occlusal trauma
Increasing mobility of teeth
Mobility decreases function
Patient comfort
To retain orthodontically repositioned teeth
To prevent drifting & overeruption
Temporary splints for CRT & surgical treatment
Prosthodontics & the Periodontium
Justify replacing missing teeth?
Benefits?
Risks?
“28 tooth syndrome”
“Shortened dental arch concept”
