BDS4 Perio-Restorative Interface 2021 PDF

Perio - Restorative Interface • What are the 3 possible positions for crown margins? • What are the advantages and disadvantages of each? Position of crown margins 1. Supra -gingival Advantages • Easy accurate impression taking & check fit of crown • Supragingival plaque control Disadvantage...

Perio - Restorative Interface • What are the 3 possible positions for crown margins? • What are the advantages and disadvantages of each? Position of crown margins 1. Supra -gingival Advantages • Easy accurate impression taking & check fit of crown • Supragingival plaque control Disadvantages • Appearance • Need adequate clinical crown height for retention Position of crown margins 2. Beneath free marginal gingiva – in the crevice Advantages • Appearance good • Reasonable access for plaque control if only 1 -1.5mm subgingival Disadvantages • More difficult to take accurate impression and check marginal fit • Plaque control more difficult the deeper subgingival Position of crown margins 3. Encroaching on the biological width Advantages • NONE Disadvantages • Loss of periodontal attachment • Impossible to clean effectively • Bleeding tissues during impression taking • Unable to check crown fit adequately 1mm JE 2mm CT attach. 1. Supragingival 2. Beneath free marginal gingiva 3. Encroaching on supracrestal tissue attachment • What determines your choice of crown margin position? Choice of crown margin position Anterior teeth – Aethetics important • In crevice – best appearance • Supragingival – margins visible • Encroaching on biological width • Persistent gingival inflammation • Further attachment loss with exposure of margins later Choice of crown margin position Posterior teeth or anteriors with no aesthetic concern • Supragingival preferable • Within crevice to be considered if a little more retention / resistance form required or need for crown margin to finish on sound tooth • DO NOT encroach on biological width! • What are the indications for crown lengthening surgery? Indications for crown lengthening surgery • Alternative to encroaching on the biological width • Access to subgingival caries • Access to subgingival fractures • Access to subgingival failing restorations • Some aesthetic problems • Inadequate crown height for a retentive preparationor adequate resistance form Suggest methods for the provisional replacement of anterior teeth during initial periodontal treatment. • Any replacement provides additional surface for plaque accumulation • Acrylic RPD • Resin retained bridge • Essix retainer Fixed or removable replacement? •Both potentially damaging if not cleansable •Some evidence for better periodontal health if fixed replacements •Balance of function & aesthetics •Prognosis of remaining teeth may be uncertain • Choose an adaptable option •Fixed option often more expensive & less adaptable •Patient choice – but options MUST be realistic RPD - Every design • Major connector clear of gingival margins • Support from palate (& a little on adjacent teeth) • Retention from • Ball ended clasps engage undercut on distal tooth surface • Flange engages buccal undercut & replaces lost periodontal tissue Alternative design • Support from palate (& a little on adjacent tooth) • Major connector clear of most gingival margins • Retention from • Adams cribs • Flange engages buccal undercut & replaces lost periodontal tissue What are the important factors when considering a periodontally -involved tooth as an abutment? • Absence of inflammation and periodontal stability • Extent of attachment loss – aesthetic compromise to avoid devitalisation • Degree of mobility • Position in arch - ? migration • Number of teeth to be replaced • Occlusion – location, loading, guidance • Patient factors including parafunctional habits When is occlusal adjustment indicated as part of periodontal therapy? • Normally carry out conventional active periodontal therapy to control inflammation before reassessing occlusion and considering adjustment • Where a clear occlusal interference is identified, e.g. fremitus when attempting to get into ICP and causing discomfort during function – initial adjustment may be justified to improve patient comfort What is a splint and what forms may they take? • Permanent – non -reversible treatment using a device to stabilise teeth with significant but stable attachment loss • Aim • improve masticatory function and comfort • Reduce risk of inadvertent extraction and unintended orthodontic tooth movement during normal function • Temporary • Used on unstable teeth to prevent mobility during the healing phase of regenerative periodontal procedure and may be removed later after healing. Where and why? • Where extensive periodontal attachment loss • Increased mobility, discomfort in function, tendency to migration due to occlusal forces • More common now following orthodontic therapy in adult patients with controlled periodontitis Types • Composite • Alone • Glass -fibre cord • Stainless steel (orthodontic retainer) • Stik Tech – pre -impregnated fibre glass reinforced materials – intimate bond between glass fibres and composite • Conventional • Joined extracoronal restorations – permanent • Adhesive cast splint • Laboratory made, permanent • Risk of caries if debonded • Vacuum -formed - Stik Tech Potential complications • Plaque retention – any splint compromises plaque control • Caries of abutment teeth – debonding • Reduced patient awareness • Occlusal overloading if too few teeth or too little attachment remaining • Devitalisation with conventional splinting if good aesthetics necessary Considerations • Appropriate treatment planning to decide whether teeth should be extracted rather than splinted • Flexible approach require due to susceptibility of patients • Composite -based approaches best • Conventional can be used later, opposite difficult • Conventional approaches have aesthetic limitations due to extent of recession • Extensive tooth preparation required • Risk of pulpal exposure • May be needed where teeth already heavily restored Considerations • Posterior teeth • consider shortened dental arch • Can use conventional single unit distal cantilevers if necessary – retention usually by longer tooth preparation • Where extensive teeth missing • Difficult • Splinting combined with implants or removable element • Precision attachments on conventional crown and bridgework or dentures • Skeleton denture with local areas of composite splinting – more simple and adaptable What can you do when a splinted tooth subsequently develops untreatable periodontitis? • Remove splint and extract tooth • Use teeth as natural pontics • Extract tooth, amputate root, construct splint using crown • Construct splint incorporating tooth, then resect root.