RMTL Flashcards
Explain the shortened dental arch concept
-9-10 pairs of occluding teeth, still allowing adequate function. Around 21 teeth
-not replacing posterior teeth (molars beyond the premolars)
-aka premolar dental arch and premolarised occlusion
-theoretically this may cause TMD, occlusal, TSL, function and aesthetic problems. Loss of OVD. Dentoalveolar compensation (raised gingival margins)
-But evidence shows these problems are not actually common
-It is a simplified approach which can maintain adequate function at minimal cost, and bilateral free end saddle dentures are hard for patients to adapt to, never mind normal dentures.
Indications and contraindications for a shortened dental arch
-Indications: good long-term prognosis of anterior and premolar teeth (no perio, caries, endo concerns) Cost issues. Never had a denture before so likely to not adapt well to it, especially with bilateral free end saddles
-Conta-indications: severe class II or III dents-alveolar malrelationship, parafunction, TMD, advanced tooth wear, advanced perio disease, patient <40 years old
Difference between transitional, temporary, provisional, trainer dentures
-Transitional= used between edentulous and edentulous States, slowly getting them used to denture as teeth have poor prognosis. Can make additions, Not permanent.
-Provisional/ temporary= Short term to allow healing of bone, either made for after extraction, or before bridge/ implant
-Trainer= if odd occlusion (disorganised, dysfunction), trial dentures to test pt tolerance
Advantages and disadvantages of transitional partial dentures
(slowly adding teeth to existing denture when pt going from edentulous to edentulous)
-Pros= simple, untraumatic, maintains function, appearance occlusal stability, use of info given by remaining teeth, helping pts adapt to dentures, can make immediate additions
-Cons= prolonged treatment, difficulty constructing a functional denture, aesthetics can be poor (mismatch of colour of added acrylic), areas of weakness where additions have been made
What type of denture will you make for a young patient with severe hypodntia
short term provisional partial dentures that is re-made as the patient grows.
Pros using trainer dentures
-can test if someone can adapt and tolerate dentures
- no tooth prep is required so completely reversible
- useful for difficult tooth wear cases/ disorganised occlusion/ dysfunction.
-Diagnostic tool: complete over closure so want to re-establish occlusion and check aesthetics and new OVD
What is the typical design for transitional/ temporary/ trainer dentures
Usually:
-all acrylic as easy to make additions and modify
-only mucosal support
-broad extension of denture base
-ensure gingival clearance
How are transitional/ temporary/ trainer dentures retentive
tight contact points
muscular control
Can add clasps
Flanges
What are the clinical stages of provisional/ temporary/immediate dentures
Preliminary impressions (as or partial dentures)
Reg if no natural contacts
Survey and design
Tooth mods if required
Major impression (as for partial dentures)
Definitive registration
Try-in
Lab replace teeth to be extracted
insert after extraction
What are the stages of transitional dentures when extracting a tooth and needing to make immediate additions
Immediate additions= adding tooth to denture prior to extraction. Done within 1 day
-primary impression with denture in, and opposing dentition
-Denture stays in impression so patient will be left without it for a morning
-Lab form –draw design, circle ‘immediate’, teeth to be replaced, pocket depths, shade, flanged or open faced
-Lab pours the impression. Gingival margins marked, long axis of tooth marked, height measured. Wax matrix made to show the occlusal surfaces.
-Teeth size selected
-Teeth removed and socket prepped – tungsten carbide bur, carver. Considering the pocket depths provided. Keep the gingival margin in tact
-Add wax over the area and add the teeth
-Remove wax (matrix made to keep tooth in position), roughen old acrylic for better chemical bond, add self cure acrylic, pressure cooker, trim and polish
-Inserted in the afternoon after extraction
What is an immediate denture
-a provisional denture made before extraction then immediately placed after
Importance of a full flange for immediate dentures
-improves retention
-protects the socket
How to overcome undercut in anterior ridge form when making immediate dentures
-Alter path of insertion
-Remove the undercut (alveolectomy)
-Don’t put acrylic in that region= open faced without flange which look good initially but over time resorption creates a gap. less retention. Less bulky
-Part flange= does not go into full sulcus, but aesthetics and food trapping a problem
Advantages and disadvantages of immediate dentures
-Pros: Quick fix, Patient never without ‘teeth’
-Cons: Design based on ‘prediction’ of ridge form, Rapid resorption after extraction (so replacement denture or rebase needed), numerous appointments for additions etc. needed after, challenging for dentist
Indications and contraindications for immediate dentures
-Acute failing dentition (pain/sepsis)
-urgency (e.g. pre- radiotherapy)
-medical indication /convenience for patient
Contraindications:
-diabetes, haemophilia, post radiotherapy (risk of MRONJ)
-multiple peri-apical/ periodontal abscesses (>3), considerable oral surgery required
-poor pt compliance, unable to manage
-very elderly
-If many teeth need extracted
=Transitional may be better
Aftercare and review appointments after immediate denture insert
-Bite on gauze and give usual post op instructions
-Kept in for 24 hours otherwise tissues will swell and will be difficult to get back in
-24 hour review appointment - examination, remove denture, saline rinse, check clots, make any adjustments using pressure cream, patient instructions regarding removal and cleaning
-1 week review - any further adjustments
-1 month review - may need rebase
Due to rapid remodelling, poor adaption of immediate denture occurs overt time. What are the solutions
Tissue won’t fully heal for a while so need a temporary solution to improve adaption.
-Temporary reline on fitting surface chair side (hard or soft lining). May need many replacements.
-Once initial remodelling has stopped (after 3-6 months) then do a Lab reline/rebase. Impression is needed, often only in localized area
Why long term recall and maintenance is required for immediate dentures
-remodelling causes poor adaption over time so need to reline
-Monitor occlusal wear, occlusal discrepancies, fractures, loss of denture teeth
-Maintain oral health
- early detection and treatment of pathology (caries, candida)
Difference between rebase and reline
-Reline- adding additional material onto fitting surface to improve adaptation.
-Rebase- same thing, but strip away fitting surface AND base and replace with new base. Because otherwise would be too bulky palatally and feel bulky for the tongue.
-Rebase for upper, don’t rebase lower dentures
-Indications= loss of fit and adaptation due to rapid resorption during first 9 months, but everything else about the denture is fine
Clinical and lab stage of reline/ rebase
-Clinic: Ease undercuts and gently roughen the fit surface. Denture used as a tray to take a wash impression of the fit surface - closed mouth technique using ZOE/ kellys paste/ light bodied silicone to get thin film so don’t increase bulk or affect the occlusal position
-Laboratory: Cast made. Registration recorded. Denture separated from the model and matrix and all impression material is removed.
- If upper denture, centre of palate trimmed away otherwise reline would be too bulky =rebase
-Denture is relocated to the model and matrix to the correct occlusion and vertical dimension. Wax is then added to the space previously occupied by impression material.
-Denture then ‘flasked’ and new acrylic packed into the reline area once the wax has been boiled away, Polymerised, de-flasked, trimmed polished
Indications for using soft lining materials
-short term trauma management (acute inflammation, soreness, ulceration)
-temporarily improving adaptation of denture during rapid resorption period
-alleviate pressure on knife edge alveolar ridge or pronounced torus palatinus
-denture induced stomatitis
-utilise undercut areas to improve retention
-reducing load to underlying tissues
-persistent soreness
-obturators (fits into defects eg. after tumour removal)
Difference between temporary and permanent liners and the materials used
Temporary= Tissue conditioners (e.g. Ufi-gel) Visco elastic gels applied chair-side
Permanent liners: Last longer (number of years)
Materials used for temporary soft lining and properties
-Tissue conditioners
-Visco elastic gels
-Initial flow and softness= allows it to adapt to get functional impression (soft elasticity)
-After initial period of flow it needs to set so impression can be processed (plastic)
-biocompatable
-usually acrylic based
-Softness means high proportion of monomer, which can cause tissue irritation
-eg. Coe Comfort, ViscoGel, Coe Soft, GC SoftLiner
Permanent soft lining materials used for relining
-silicone based - molloplast-b
-heat-cured acrylic
-light-cured acrylic
-heat-cured fluoroelastomer
Disadvantage of heat cured acrylic over light cure for permanent soft liners
Disadvantage to heat cure= Plasticiser gradually leaches out so becomes less soft over time
Is silicone or acrylic based permanent soft liner material preferred. Why they can fail
Silicone-based is preferred
-Both materials tend to fail most due to fracture of acrylic base (as accommodating soft lining means reducing acrylic so it is thinner and weaker and more vulnerable to fracture).
- Surface degradation (leaching of plasticisers)
-Bond failure to rest of denture
-Discolour over time
-Chipping/ breaking away
Minimum thickness of permanent soft lining materials
2mm
Advantages and disadvantages of over dentures
-Pros: improves retention, preserves bone, sensory feedback, psychological benefit
-Cons: potential for caries and perio disease if poor OH, lack of space may cause problems setting artificial teeth, undercuts areas can cause problems
Steps for immediate over dentures
Primary impression
Design
Major impression
Reg
Try-in
Overdenture abutment prepped to maximum of 2-3mm and extract the remaining teeth.
Insert
Lab- Plaster teeth to be retained as over denture abutments will be domed on the model to a height of 3-4mm above the gingival margin. Slightly tapered to remove undercut. Doming on cast is done before natural teeth are on clinic so plaster abutment deliberately larger than necessary to ensure it still fits. Artificial teeth set over top, waxed up, processed
Review- reline to fill void above the over denture abutment. Acrylic also placed into area
Differences between implants and teeth
-Implant has osseointegration, direct contact with bone, no PDL, immobile, cannot migrate with growth, increased risk of peri-implantitis
Components of an implant
-implant in the bone
-abutment
-abutment screw
-crown
Indications/ advantages of implants
-Spaced dentitions
-Avoids tooth preparation
-Avoids RBB retainer shine through
-Avoids denture problems – e.g. accommodating a deep overbite
Disadvantages / risks of implants
-Surgical side effects after raising a flap- Soreness and inflammation, but this should resolve.
-Possible damage – inhaling small pieces, damage to adjacent structures
-Aesthetic challenges especially with the gingivae overlying the implant
-Lengthy treatment, 4-8 visits
-non bio-responsive, cannot move with growth or ortho
-costly
-increased/ life long risk of peri-implantitis - requires lifelong maintenance
Contraindications and risk factors for implants
-children (still growing, difficult to tolerate and understand)
-lots of co-morbidities
-systemic risks factors affecting tissue integration and healing: smoking, diabetes, immunosuppression, bisphosphonates, head and neck radiotherapy
-parafunctions
-perio disease
-high smile line means less likely to get away with poor aesthetics
-implant in dynamic occlusion (try get on natural teeth, if not shared guidance)
How much mesial-distal space is required for implants
-need 6.5mm between adjacent teeth. Because…
-need 1.5mm between implant and adjacent tooth on each side
-implant normally 3.5mm wide
-Otherwise get soft tissue collapse
What is minimum age to give implants
mid 20s
definitely not as teenager
Things to assess when have an implant patient
-Examining appearance, OH, recession, fistula, pocket probing
-assess if peri-implantitis
-Assess changes in risk status - smoking, diabetes etc.
Explain Hybrid and micro-fill composites. Which are stronger, which are better polished
- Hybrid:
-Filler particles are a mixture of large/ medium/ small
-Improved physico-mechanical properties
-used for normal restorations
-Cannot get good polish that is maintained - Micro-fill composites
-Smaller filler particle so better ability to be polished and retain good polish
-Disadvantage – weak = don’t use in load bearing areas
What type of articulator is used when face bow used for wear cases when changing OVD
semi-adjustable
List ways to create space
-reduce height of opposing tooth
-increase OVD
-Dahl concept
-Distalization (CR)
-Orthodontics
-Crown lengthening (used with other techniques)
Difference between finding space and making space to place restorations
-Finding space: If OVD decreased and FWS +++. Patient over closing so fairly easy to re-build the occlusion as you have space.
-However, need to making space if not wanting to change the OVD (FWS 3-5mm). OVD is not changed due to dentialveolar compensating
Explain the Dahl concept. How much space can be obtained. Example of when it is used
-Place composite restorations anteriorly on worn teeth
-this opens the bite and causes posteriors to over erupt
=Increase in OVD and disclusion of posterior teeth
=Re-establishment of posterior occlusion through extrusion/ over eruption of posteriors and intrusion of anteriors
-no tooth prep required, but may take several months for movements
-eg. if localised wear on upper anterior palatal surfaces. Or posterior over eruption into edentulous space
-2-3mm space
What space creation technique useful for localised wear, and generalised wear
-Localised= reducing height of opposing tooth (for small adjustments), Dahl concept, distalization, crown lengthening
-Generalised= increasing OVD, crown lengthening
What is distalization
An option for creating space
using CR
using a large horizontal component of RCP-ICP slide
Reasons for diagnostic wax ups for wear cases
-To create a 3D wax template which can be shown to the patient and shared between clinic and laboratory
-To assess aesthetics and function
-To identify possible difficulties and solutions
-To ascertain a new VD (if required)
-To create a matrix to use clinically for restorations
-Essential for treatment planning
Reasons for needing a semi adjustable articulator, opposed to an average value
-If occlusion is being re-organised
-If an increase in OVD is planned
- new restorations are involved in dynamic occlusion ( even when conforming to the existing occlusal scheme)
-If removal of occlusal interferences are planned (can do trial adjustment)
-if providing a hard occlusal splint for TMD problems or before treatment to stabilise jaw position
Uses of hard and soft splints
-Soft - protect restorations from the effects of bruxism, distributes heavy load
-Hard= alters occlusal equilibrium. if grinding through soft splint. Changes patients habits and muscle memory to prevent grinding by having no posterior contacts. Helps with TMD
What is the hard and soft material used for appliances (eg. splints) that use a vacuum forming machine
*Ethylene vinyl acetate ( EVA) – soft
*Polyvinyl chloride ( PVC) - hard
*Poly Carbonate – hard
Soft= splints for bruxism, mouth guards, sleep apnoea devices
Hard= Ortho retainers. Splints for retaining avulsed teeth. Splints for TMD. Bite raising appliances
What appliances can help treat sleep apnoea
-mandibular advancement splint (MAS) can treat sleep apnoea and can also prevent snoring
-improves breathing during sleep
-Made of soft EVA in a vacuum machine
Purpose of Kois dento facial analyser and Facebow. What interocclusal recordings record
-KDFA= used to register and transfer the patient’s occlusal plane and vertical facial mid-line
-FB= used to register the relationship between the maxilla and the condyles/ TMJ. Hinge axis
-Static Interocclusal recordings are taken at the same time as the FB/KDFA that relate the mandible to the maxilla - CR or RCP
Not needed if in ICP and restoration not in dynamic occlusion
Stages of composite build up using diagnostic wax up
-Alginate impression and face bow
-Casted and Semi adjustable articulator
-Assess space required to restore
-Wax to build up
-Putty or Memosil (clear) matrix of cast. And sectioned
-Bevel enamel or sand blast to improve bond
-Isolate, PTFE tape on adjacent teeth
-Etch, bond, load single tooth of matrix with composite and place over teeth
-Cure polish, then do the rest of the teeth
When to use centric relation with diagnostic casts
-when planning to adjust or reorganise the occlusion /changing vertical dimension.
-establishing a new inter cuspal position in centric relation. This would include composite build ups of wear cases
Why we re-organise
-lack of interocclusal space for replacing missing tooth structure (due to worn, TSL, dentoalveolar compensating). Or replacing missing teeth and no space in ICP
-when restoring all teeth in an arch extra coronally. This can be done in ICP but is more conservative in CR
