Relines/repairs/rebasing/addition Dentures Flashcards
How often is tissue conditioner used
they are used most commonly where you want to settle down inflammed tissues prior to taking primary imps - e.g. in cases of denture related stomatitis, but need to be replaced every couple of days
When is tissue conditioner used as a functional imp
- patient to go away with the tissue conditioner for a few days to capture a functional impression, if using them for a functional impression (though this is more specialist type treatment in a hospital and probably rarely done in general practice) some people may just keep material in place for an hour or so, others may send patient away for a couple of days - depends upon the operator you can either do it
- can get pt to chew on wet towel with tissue conditioner in place to capture ridge
How to add tooth onto a denture
Study condition and design of denture, to ensure that an addition is possible. You will then take an impression using alginate in a stock tray of the denture in-situ, imp of opposing arch, shade and interocclusal record.
What may cause a denture to break? (5)
- Fatigue:
Possibly design related
• e.g. anterior labial notch, other frenal notches - Thin acrylic
- Around teeth or over retained roots
- Because of deep overbite so need to make it thin
- Teeth are very worn down so there is little occlusal clearance so has to be thin - Trauma
- Dropping it
- Incorrect occlusal balance, creating stress in certain areas of acrylic - Clasps
- If placed too deep in an undercut
- Been adjusted too often
- Patient may bend it accidentally/deliberately - Breaks again in the same place:
- Because cold cure acrylic has inferior mechanical properties.
- Previous stresses may still be there, it is still weak in that area.
Are there any situations where a repair or addition may not be possible?
- if the denture doesn’t fit accurately in the mouth eg it has distorted
- if metal work is a long way from the tooth to be added and it’s not possible to laser weld
- very old and worn dentures
What potential problems may be encountered when fitting a denture following an addition? How do you overcome these?
POTENTIAL PROBLEMS:
- insertion of denture, if path of insertion not taken into account by the lab
- incorrect occlusion
- retention problem
- undercut not blocked out by the lab
- denture doesn’t fit well - distortion of the impression
OVERCOME THESE:
- check and correct the occlusion
- remove the undercut
- activate the clasps
- may need to remake the addition part of the denture
Indications for rebasing
- Warped base (distorted)
- Base is constantly fracturing along line of weakness
- Patient with immediate denture usually after 3-6months.
- Diabetic patient that complains of continuous poor retention and stability due to bone resorption.
- Geriatric patient and very poorly health patients that can’t bear the visits of new denture construction.
- Socioeconomic status and economic consideration.
Contraindications for rebasing
- Severely resorbed ridge, it is better to make new denture with advanced impression techniques or make implant or overdenture.
- Aesthetically not acceptable dentures, especially teeth shade.
- Flabby tissue covering the residual ridge, unless the condition is treated.
- Speech problems due to incorrect setting of teeth
What are common causes of midline fracture
Common causes of midline fracture:
- Design features e.g. deep frenal notch
- Resorption of alveolar ridge
- Displaceable denture bearing tissues
- Occlusal wear of teeth
- Heavy occlusal load
- Impact + fatigue (denture sitting close to hard palate but not resorbed ridges, stresses concentrated in midline, that area specifically more prone to fracture) - so any factor influencing stress distribution can predispose to fracture
How to repair midline fracture
- Examine extent of fracture, ensure no other fracture, ask pt if happy with denture beforehand
- Stick pieces back together with sticky wax
- Any undercut blocked out with wax/putty
- Paint vaseline/separating medium onto fit surface
- Stone plaster poured into fitting surface
- After stone set, denture removed from cast and cleaned from any traces of sticky wax
-Fractured edges widened along fractured lines & bevelled towards polished surface to increased bonding SA
- Retention grooves/dove tails made to strengthen repaired joints
- Cast painted with vaseline & denture secured to cast with rubber bands
- Self cure acrylic resin applied to modified fracture area until area overfilled, denture cured in pressure pot
- Deflasking, finishing and polishing done as usual
- MAY PLACE METAL IN AREAS OF REPEATED FRACTURE - lighter than conventional CoCr
DISADVS of repairing midline fracture
- May not fit well after repairs
- Occlusal changes can occur
When might you need to make a new denture after fracture?
- Broken pieces cant be assembled accurately, more than 2 fractured pieces etc
- If denture needs to be replaced anyway due to poor fit or occlusal wear/any other reason
Indirect technique for hard reline
(pt will be without denture)
- Imp taken (open/closed mouth technique) using denture like special tray with
ZOE or silicone after border moulding with green stick, removing undercuts etc
^^ Open mouth = you taking imp, closed mouth = get patient to bite down during
imp (more common)
- Lab adds lining
Chairside process for hard reline, advs and disadvs
Direct technique:
- Chairside addition
- Look for undercuts in mouth (wont be able to remove it)
- Adv = pt can keep denture
Disadv of chairside:
- Materials have an exothermic setting reaction
- Materials are porous and can develop bad odour over time
- Low colour stability
- Also impossible to remove once material has set
- No control over the inevitable increase in OVD
DISADVS of hard reline overall
- Could add too thick of a layer of acrylic to fitting surface of denture = dropping
down occlusal plane = more tooth showing, affecting aesthetics - Can affect freeway space, affecting function
List types of materials used for permanent soft reline (2)
- Plasticised acrylic resin e.g. Eversoft
- Silicone rubbers e.g. Molloplast B (most commonly used as heat cured permanent soft line)
DISADVS of permanent soft reline
- 2-3mm thickness of material required
- Reduction of denture base material to compensate- fracture of denture base common
- Extensive bony prominences
- Failure of adhesion of silicone soft lining to denture base although more resilient and elastic
- Acrylic resin harden over time and more readily distort
- Difficult to adjust
- Staining
- Colonisation with Candida
- Harder to carry out chairside permanent soft reline than indirect version where lab applies the reline (after using pts denture as special tray)
- MUST NOT INCREASE PTS OVD
Indications of permanent soft reline
- Atrophic / knife edge alveolar ridge esp. clenching or grinding habit (mucosa
squished between denture and knife ridge = painful) - Superficial mental nerve
- Extensive bony prominences
- Congenital / acquired oral maxillofacial defects
- Xerostomia?
Contraindications of permanent soft reline
- Excessive resorption - denture unstable, can’t be positioned properly
- Denture with bad aesthetics/jaw relationships
- If denture has speech problems
- Soft tissue inflammation present
- Severe osseous undercuts
Indications for temporary soft reline (11)
- After recent XLA e.g for fit of immediate denture (fill space with temp soft reline after resorption)
-After surgery to remove hyperplastic tissue - Diagnostic aid e.g to establish whether permanent soft liner would benefit patient
- loss of retention
- instability
- food trapping
- abused mucosa
- as a temporary measure to maintain function of an immediate denture
- Border additions
- To improve retention
- Around overdenture abutments
DISADVS of temp soft reline
- Plasticiser and solvent leach out over time = lining will need replacing
- Porous and stain easily
- Avoid when mental nerve is superficial
- Need more thickness for it to be effective which can weaken the denture.
Types of temp soft reline material (2)
- Acrylic based preformed sheets- not really effective and need replacement, bought by patient
- Powder-liquid formulations eg PEMA, or PMMA (powder) and MMA/n-butyl methacrylate (liquid) (chairside by dentist), plasticiser (maintains softness), peroxide inhibitor
COE SOFT
