Removable partial dentures (PRD’s) are used to replace one or more teeth in a jaw. Once all teeth are missing, a full denture will be required.
They may act as a permanent solution for teeth replacement, or they may just be provisional appliance – an appliance that fulfils a short term purpose while other longer term fixed options are planned.
Types of partial dentures (RPD’s)
In the past, partial dentures were more commonly used as a permanent solution for the replacement of teeth.
With the advent of dental implants, partial dentures are now more often used as temporary or ‘Provisional’ devices.
In some instances, a dental implant (the current state-of-the-art tooth replacement system), or fixed bridgework (the next best alternative) may not be suitable for the replacement of a missing tooth.
This can be due to lack of bone to support the implant, a lack of space due to drifting of surrounding teeth, the presence of active and aggressive gum disease, or the need to replace lost bone to return youthful cheek and lip support.
For people in these situations, it has always been the case that RPD’s provide an alternative for replacement of missing teeth and bony structure.
Vitallium
(Tooth and tissue supported)
Vitallium is a brand of Cobalt chrome denture material that is currently the most highly regarded material in its class. It provides a metal framework which serves as the dentures skeleton.
It is extremely strong, rigid and can be made very thin so it is unobtrusive.
It is also extremely biocompatible and will not cause allergies as some other alloys containing Nickel or Beryllium can.
Denture teeth and pink acrylic to mimic lost gum tissue are firmly attached to the framework.
The framework design often incorporates rests and clasps.
The clasps are designed to grip the teeth tightly to maintain the stability of the denture and prevent any movement during use. The clasps can be cast to be small in size so they are less visible and are less likely to distort over time as stainless steel clasps will.
The rests suspend the denture on teeth (so it does not rest completely on soft tissue). This not only helps stabilize the plate in function, but also helps to reduce the bite forces placed on the residual ridges (the gum areas where the teeth previously were). Excessive forces to this ridge will lead to its accelerated shrinkage with denture looseness the result.
Being so accurate in fit, Vitallium plates are also less likely to generate as much damaging torque (tipping and twisting forces) on the remaining anchor teeth.
Flexidentures – Valplast
(Tissue supported)
These dentures are produced from a form or nylon rather than acrylic. They are extremely tough, light, flexible and resistant to fracture.
They are considerably thinner than traditional acrylic RPD’s. Coupled with their flexibility this makes them very comfortable and stable in function in comparison.
Rather than metal clasps to help retain them, they have gum coloured finger like extensions that grip into spaces around the gum line of surrounding teeth. They provides great resistance to dislodging forces while in many cases being almost invisible.
They are a great option for people who are allergic to acrylic.
They do however come with some disadvantages. They are more costly to produce than acrylic, and are difficult to refit or ‘reline’, repair, or add additional teeth to in the future if required.
A RPD can provide temporary tooth replacement while other long term solutions such as dental implants or dental bridges are being considered. There are two types we commonly use at Melbourne Dentist:
Essix appliance
(Entirely tooth supported)
A temporary device that allows the healing of gum & bone in an extraction site – entirely tooth supported so pressure is removed from the delicate tissues as they heal.
It’s like an ultra thin, see through mouthguard that is trimmed to follow the gum line of the teeth surrounding the missing tooth.
Tooth coloured resin is added to the inside of this appliance where the tooth is to be lost and often mimics exactly the tooth being removed.
These are generally used to replace one or a few teeth only.
They are most often made as an ‘immediate’ denture to replace a tooth straight after it is removed. They are extremely easy to get used to and can sometimes be so firm in place as it’s a little difficult to remove.
One minor disadvantage is that they change the bite slightly while they are being worn and can thus can only be used for a few months.
The Essix appliance is very commonly used after a tooth is removed and prior to implant placement. This is because they are very gentle and supportive to the gum tissues surrounding this area, helping with gum aesthetics around the final implant crown.
Acrylic partial plate aka a ‘flipper’
(Tissue supported)
These appliances are often called ‘flippers’, so called because they can be easily flipped out with the tongue.
They are kept in place by clinging around the necks of other teeth, often with the help of metal wire clasps.
They need to be relatively thick to resist fracture so they are generally less comfortable than other options.
However, they are quick, easy and cheap to produce.
They are most often used as immediate dentures, placed in straight after a tooth or teeth are removed. In many of these cases, time is required for healing until a more permanent solution can be carried out.
Permanent RPD's
In some instances, a dental implant (the current state-of-the-art tooth replacement system), or fixed bridgework (the next best alternative) may not be suitable for the replacement of a missing tooth.
This can be due to lack of bone to support the implant, a lack of space due to drifting of surrounding teeth, the presence of active and aggressive gum disease, or the need to replace lost bone to return youthful cheek and lip support.
For people in these situations, it has always been the case that RPD’s provide an alternative for replacement of missing teeth and bony structure.
Vitallium
(Tooth and tissue supported)
Vitallium is a brand of Cobalt chrome denture material that is currently the most highly regarded material in its class. It provides a metal framework which serves as the dentures skeleton.
It is extremely strong, rigid and can be made very thin so it is unobtrusive.
It is also extremely biocompatible and will not cause allergies as some other alloys containing Nickel or Beryllium can.
Denture teeth and pink acrylic to mimic lost gum tissue are firmly attached to the framework.
The framework design often incorporates rests and clasps.
The clasps are designed to grip the teeth tightly to maintain the stability of the denture and prevent any movement during use. The clasps can be cast to be small in size so they are less visible and are less likely to distort over time as stainless steel clasps will.
The rests suspend the denture on teeth (so it does not rest completely on soft tissue). This not only helps stabilize the plate in function, but also helps to reduce the bite forces placed on the residual ridges (the gum areas where the teeth previously were). Excessive forces to this ridge will lead to its accelerated shrinkage with denture looseness the result.
Being so accurate in fit, Vitallium plates are also less likely to generate as much damaging torque (tipping and twisting forces) on the remaining anchor teeth.
Flexidentures – Valplast
(Tissue supported)
These dentures are produced from a form or nylon rather than acrylic. They are extremely tough, light, flexible and resistant to fracture.
They are considerably thinner than traditional acrylic RPD’s. Coupled with their flexibility this makes them very comfortable and stable in function in comparison.
Rather than metal clasps to help retain them, they have gum coloured finger like extensions that grip into spaces around the gum line of surrounding teeth. They provides great resistance to dislodging forces while in many cases being almost invisible.
They are a great option for people who are allergic to acrylic.
They do however come with some disadvantages. They are more costly to produce than acrylic, and are difficult to refit or ‘reline’, repair, or add additional teeth to in the future if required.
Temporary RPD's
A RPD can provide temporary tooth replacement while other long term solutions such as dental implants or dental bridges are being considered. There are two types we commonly use at Melbourne Dentist:
Essix appliance
(Entirely tooth supported)
A temporary device that allows the healing of gum & bone in an extraction site – entirely tooth supported so pressure is removed from the delicate tissues as they heal.
It’s like an ultra thin, see through mouthguard that is trimmed to follow the gum line of the teeth surrounding the missing tooth.
Tooth coloured resin is added to the inside of this appliance where the tooth is to be lost and often mimics exactly the tooth being removed.
These are generally used to replace one or a few teeth only.
They are most often made as an ‘immediate’ denture to replace a tooth straight after it is removed. They are extremely easy to get used to and can sometimes be so firm in place as it’s a little difficult to remove.
One minor disadvantage is that they change the bite slightly while they are being worn and can thus can only be used for a few months.
The Essix appliance is very commonly used after a tooth is removed and prior to implant placement. This is because they are very gentle and supportive to the gum tissues surrounding this area, helping with gum aesthetics around the final implant crown.
Acrylic partial plate aka a ‘flipper’
(Tissue supported)
These appliances are often called ‘flippers’, so called because they can be easily flipped out with the tongue.
They are kept in place by clinging around the necks of other teeth, often with the help of metal wire clasps.
They need to be relatively thick to resist fracture so they are generally less comfortable than other options.
However, they are quick, easy and cheap to produce.
They are most often used as immediate dentures, placed in straight after a tooth or teeth are removed. In many of these cases, time is required for healing until a more permanent solution can be carried out.
The role of implants and partial dentures
The strategic placement of one or two dental implants may not dramatically increase costs, but could significantly improve the stability of a RPD.
The most common case where this can be used to great effect is where a ‘free end saddle’ is present. This is where several teeth are missing on one side with no end back tooth to anchor onto. Such dentures are notorious for lifting at the back during use.
With an implant in place where the last tooth would have been, a small ‘Locator’ abutment can be attached to the top of it. This small device (sitting on top of the implant) protrudes just above the gums and will latch onto the underside of the denture and hold it very firmly in position.
The production process.
In the service industries of the modern world, speed of service can be valued higher than all else. Some dental providers proudly advertise that dentures can be made in a few short visits.
Here at Melbourne dentist, if speed and cost are paramount to you, we have the necessary experience to condense the process to deliver economy appliances fast.
All ‘provisional’ appliances we produce are made with this in mind. However, a Premium permanent RPD can not be made in this fashion. A Premium RPD requires a meticulous adherence to process, where the inclusion of extra steps ensures the absolute best quality appliance.
Below is an outline of the ‘average’ Vitallium process:
Conventional evaluation.
Oral tissue health, bite and jaw joint function as well as oral cancer screening are amongst the things we check.
It’s important to ensure that the remaining teeth are in good condition – particularly the ones that will be asked to support the denture.
- The gums and supporting bone around each tooth will be assessed and therapy provided as required. Vitallium production may be halted until the certainty of these teeth’s longevity is decided.
- The supporting teeth will be assessed and restored if appropriate. Longer lasting restorations should be considered so that these restorations are likely to last at least as long as the Vitallium will. Vitallium production may be halted until the certainty of these teeth’s longevity is decided.
Any surgery that may be required (for example tooth removal or implant placement) has to be completed and has healed before further appointments for denture production.
Aesthetic evaluation.
This analysis focuses on the your aesthetic wants and needs but is only important if most of your front teeth are missing (or if you wish to change the appearance of your remaining teeth).
You are guided by us in this process by using a digital smile guide and smile test questionnaire. This process will help us determine your preferences for teeth shape, colour, teeth positioning, improved lip and cheek support and numerous other processes used to customise the dentures.
Video capture
Captured moments from video recordings allow us to assess how your current denture relates to your face during normal speech, smiling and laughter. By studying these we can readily determine what will be needed to improve your smile.
Impressions of your mouth are taken.
Plaster study models are fabricated from these impressions.
Before you come back for your next visit:
- A digital smile blueprint is produced using information we discovered from your aesthetic evaluation and video capture. (This is only carried out if most of your front teeth are being replaced or modified with other restorations for enhanced aesthetics)
- ‘Wax rims’ and a ‘Special tray’ will be fabricated by our laboratory to be used at your next visit.
Smile design preview and feedback
The digital smile blueprint is presented to you using computer-generated images simulating your new teeth.
Adjustments to the design are made if necessary based on feedback from you.
‘Wax rim’ Registration
Horseshoe-shaped rims made of wax are made to fit the plaster study models.
Multiple additions and subtractions are made to these rims after repeatedly trying them in the mouth.
The final shape of these rims will simulate the position of the teeth, gums and level of lip and cheek support.
Guide plane and rest preparations.
Minor modifications will be made to some teeth and filling surfaces to ensure a tighter fit and correct seating of the framework onto teeth. This is done after carefully studying the plaster study models.
‘Secondary’ Impressions of your mouth are taken.
The previous impressions are used to make a plastic device that can be used to take an even more accurate impression to deliver a precision fit of the metal framework. Again, plaster study models are fabricated from these impressions.
Vitallium framework try-in
This is a very short, but extremely important visit. Before any wax or plastic additions are made to the metal framework, it is tried into your mouth to ensure it fits exactly.
The lab returns this mock-up ready for a further try-in visit.
Vitallium framework and teeth mock-up try-in
This should also be a very short visit and is used to ensure you are completely happy with the new teeth set-up.
Video capture
Captured moments from video recordings allow us to assess whether the final proposed set up is indeed correct. (This is only carried out if most of your front teeth are being replaced or modified with other restorations for enhanced aesthetics).
Vitallium delivery
The denture is placed in your mouth and the bite is adjusted for correct balance if required. Specific instructions will be given on the care of these dentures and you will likely be asked to return for a follow up within the next seven days.
Getting to know you
Conventional evaluation.
Oral tissue health, bite and jaw joint function as well as oral cancer screening are amongst the things we check.
It’s important to ensure that the remaining teeth are in good condition – particularly the ones that will be asked to support the denture.
- The gums and supporting bone around each tooth will be assessed and therapy provided as required. Vitallium production may be halted until the certainty of these teeth’s longevity is decided.
- The supporting teeth will be assessed and restored if appropriate. Longer lasting restorations should be considered so that these restorations are likely to last at least as long as the Vitallium will. Vitallium production may be halted until the certainty of these teeth’s longevity is decided.
Any surgery that may be required (for example tooth removal or implant placement) has to be completed and has healed before further appointments for denture production.
Aesthetic evaluation.
This analysis focuses on the your aesthetic wants and needs but is only important if most of your front teeth are missing (or if you wish to change the appearance of your remaining teeth).
You are guided by us in this process by using a digital smile guide and smile test questionnaire. This process will help us determine your preferences for teeth shape, colour, teeth positioning, improved lip and cheek support and numerous other processes used to customise the dentures.
Video capture
Captured moments from video recordings allow us to assess how your current denture relates to your face during normal speech, smiling and laughter. By studying these we can readily determine what will be needed to improve your smile.
Impressions of your mouth are taken.
Plaster study models are fabricated from these impressions.
Before you come back for your next visit:
- A digital smile blueprint is produced using information we discovered from your aesthetic evaluation and video capture. (This is only carried out if most of your front teeth are being replaced or modified with other restorations for enhanced aesthetics)
- ‘Wax rims’ and a ‘Special tray’ will be fabricated by our laboratory to be used at your next visit.
Design preview and set-up
Smile design preview and feedback
The digital smile blueprint is presented to you using computer-generated images simulating your new teeth.
Adjustments to the design are made if necessary based on feedback from you.
‘Wax rim’ Registration
Horseshoe-shaped rims made of wax are made to fit the plaster study models.
Multiple additions and subtractions are made to these rims after repeatedly trying them in the mouth.
The final shape of these rims will simulate the position of the teeth, gums and level of lip and cheek support.
Guide plane and rest preparations.
Minor modifications will be made to some teeth and filling surfaces to ensure a tighter fit and correct seating of the framework onto teeth. This is done after carefully studying the plaster study models.
‘Secondary’ Impressions of your mouth are taken.
The previous impressions are used to make a plastic device that can be used to take an even more accurate impression to deliver a precision fit of the metal framework. Again, plaster study models are fabricated from these impressions.
Framework try-in
Vitallium framework try-in
This is a very short, but extremely important visit. Before any wax or plastic additions are made to the metal framework, it is tried into your mouth to ensure it fits exactly.
The lab returns this mock-up ready for a further try-in visit.
Denture test-drive
Vitallium framework and teeth mock-up try-in
This should also be a very short visit and is used to ensure you are completely happy with the new teeth set-up.
Video capture
Captured moments from video recordings allow us to assess whether the final proposed set up is indeed correct. (This is only carried out if most of your front teeth are being replaced or modified with other restorations for enhanced aesthetics).
Denture delivery
Vitallium delivery
The denture is placed in your mouth and the bite is adjusted for correct balance if required. Specific instructions will be given on the care of these dentures and you will likely be asked to return for a follow up within the next seven days.
Benefits and risks of RPD’s
- They can be an excellent cost-effective way to replace numerous teeth
- If a minimum of four teeth can be kept (two towards the front and two towards the back), these teeth can be used to ‘clasp’ onto making the RPD markedly more stable than a full denture alternative
- They are a little easier to manage to keep clean than fixed bridges as they are removable
- They can stop the remaining surrounding and opposing teeth from moving into the gaps.
- Such movement will always put the teeth involved under increased stress leading to further breakdown and collapse of the bite
- If a more permanent solution such as an implant or bridge is being considered, such movement can make the fixed options impossible to carry out if limited spaces remain
- They can return chewing function and allow for proper nutrition and digestion
- They can be used to support the cheeks and lips as a ‘sunken’ look can develop with multiple tooth loss.
- They can help protect the remaining teeth.
- With fewer correctly connecting teeth, the remaining teeth will be forced to take on increased loads leading to them chipping and breaking.
- In the absence of back teeth, the front teeth can be overloaded and are more likely to drift apart or to break
- They can help to retain correct ‘vertical dimension’.
- When fewer teeth remain, those that do will tend to drift and wear down leading to a collapse of the bite.
- This puts undue stress on your jaw joint and effectively places your chin closer to your nose.
- Plaque will tend to accumulate more around the areas where the denture contacts the teeth putting these areas at a greater risk of decay and gum disease.
- If RPDs are not designed or maintained correctly (including regular relines) they can accelerate damage to surrounding structures.
- Rocking plates will increase forces on teeth they rest on or against causing them to loosen
- They can apply excess pressure to the soft issues and bone they are supported by causing them to shrink away. This will serve to make future appliances larger, heavier and more difficult to use
- They can cause irritation to underlying tissues and promote infections in these areas
Benefits
- They can be an excellent cost-effective way to replace numerous teeth
- If a minimum of four teeth can be kept (two towards the front and two towards the back), these teeth can be used to ‘clasp’ onto making the RPD markedly more stable than a full denture alternative
- They are a little easier to manage to keep clean than fixed bridges as they are removable
- They can stop the remaining surrounding and opposing teeth from moving into the gaps.
- Such movement will always put the teeth involved under increased stress leading to further breakdown and collapse of the bite
- If a more permanent solution such as an implant or bridge is being considered, such movement can make the fixed options impossible to carry out if limited spaces remain
- They can return chewing function and allow for proper nutrition and digestion
- They can be used to support the cheeks and lips as a ‘sunken’ look can develop with multiple tooth loss.
- They can help protect the remaining teeth.
- With fewer correctly connecting teeth, the remaining teeth will be forced to take on increased loads leading to them chipping and breaking.
- In the absence of back teeth, the front teeth can be overloaded and are more likely to drift apart or to break
- They can help to retain correct ‘vertical dimension’.
- When fewer teeth remain, those that do will tend to drift and wear down leading to a collapse of the bite.
- This puts undue stress on your jaw joint and effectively places your chin closer to your nose.
Risks
- Plaque will tend to accumulate more around the areas where the denture contacts the teeth putting these areas at a greater risk of decay and gum disease.
- If RPDs are not designed or maintained correctly (including regular relines) they can accelerate damage to surrounding structures.
- Rocking plates will increase forces on teeth they rest on or against causing them to loosen
- They can apply excess pressure to the soft issues and bone they are supported by causing them to shrink away. This will serve to make future appliances larger, heavier and more difficult to use
- They can cause irritation to underlying tissues and promote infections in these areas
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