01: The Edentulous Ridge Flashcards
Where do the differences in morphology of alveolar bone depend on?
Differences in morphology of alveolar bone are depended on:
- the size and shape of the teeth
- events occurring during tooth eruption
- the inclination of the erupted teeth
What differences can be observed in different biotypes?
Differences observed in different biotypes include:
1. long and narrow teeth , compared with subjects who have short and wide teeth ,
2. appear to have a more delicate alveolar process and,
3. in particular in the front tooth regions , a thin , sometimes fenestrated , buccal bone plate
Subjects with long and narrow teeth, compared with subjects who have short and wide teeth, appear to have a more delicate alveolar process and, in particular in the front tooth regions, a thin, sometimes fenestrated, buccal bone plate.
What do we expect when we have subgingival restoration margins on a thin biotype?
Recession
What do we expect when we have subgingival restoration margins on a thick biotype?
inflammation
How can you also name the functional unit described in Fig. 3-2?
Attachment apparatus , which includes the
1. bone,
2. cementum,
3. periodontal ligaments.
It is well documented that following multiple tooth extractions and the subsequent restoration with removable dentures, the size of the ridge will become markedly reduced, not only in the horizontal but also in the vertical dimension
Do we expect to see the same bone resorption in all patients?
No , there is a wide variation in the degree of bone resorption and amount of remaining bone among the patients.
It comes down to thin or thick biotype. It depends on the pressure on that area, why you lost the teeth, due to caries or perio. By having recession, the root is exposed, that means there is no bone there.
By having a single tooth extracted , do we expect to see a different process of resorption compared to multiple teeth ?
Same process of resorption , how much it will be resorbed it will depend on the factors discussed.
Even on a single tooth you can see the change in the buccal aspect.
Picture: the amount of buccal resorption that occurs
Try not to deliver a lot of things when you do an extraction. The problem is unpredictable. That is the major issue. You know it will happen (resorption) but not how much.
What percentage of bone reduction do we expect to see in 3 and 12 months of healing , concerning the bucco-lingual or bucco-palatal dimension , following tooth extraction?
- 3 months: The bucco‐lingual/‐palatal dimension during the first 3 months was reduced by about 30% .
- After 12 months the edentulous site had lost at least 50% of its original width.
Even if you do something in 3 months, it might change a bit more later on, in the year. Consider the possible change.
Furthermore, the height of the buccal bone plate was reduced and after 12 months of healing the buccal prominence was located 1.2mm apical of its lingual/palatal counterpart.
What would be the clinical ramifications concerning prosthetic rehabilitation (implant or tooth supported)?
- Replacing lost teeth with implants – consider bone augmentation
- Provide a bridge – there might be space between pontic, bridge, bone
- For both of these points – when the bone is resorbed then the bone will continue resorbing and the patient will complain of aesthetics anteriors or food impaction on the posteriors
- In a tooth supported restoration, the problems are less and more predictably handled. The biggest issue in the anteriors are the aesthetics, but food impaction if it happens you can replace the bridge, if you use implants then you need to plan ahead.
Where does the degree of buccal bone resorption depend on?
The degree of buccal bone resorption plate following tooth extraction was dependent on its original dimension .
- Thin bone plates (<1 mm wide) lost substantially more dimension (width and height) than plates that were >1 mm wide.
- More or less, it depends on the original dimension of the area (3D). Height and width play a role .
- You have to remember as dentists we work with mm. 1 mm here it makes a difference. If you have a bone plate less than a mm wide, you expect to lose a lot.
- Even if the plate is more than 1 mm you expect to have resorption, but you might get away with it.
In the anterior region, more than 80% of the sites have less than a mm of bone width.
This is where most people do immediately implant placement.
So, in more than 80% of the sites you will get a lot of bone resorption. In the aesthetic area, it is more difficult to provide an aesthetic result because you will have resorption.
Which factors will influence the changes of the alveolar bone proper following tooth extraction?
- Tooth-related diseases , (ex: periodontitis or periapical periodontitis)
- Traumatic injuries (ex: during extraction or after an accident – falling down the stairs)
In Fig. 3-9 we can observe two different classifications of an edentulous area. Give a brief description.
a classification of residual jaw shape :
cross-sectional shapes of the five different groups of both upper and lower jaws based on the volume of remaining mineralized bone
- In groups A and B , substantial amounts of the ridge still remain , whereas
- in groups C, D, and E , only minute amounts of hard tissue remain .
- A and B – can place a full mouth denture or implants
- C, D, E – problems with placing a denture or implant
In Fig. 3-9 we can observe two different classifications of an edentulous area. Give a brief description.
4 different groups of jaw bone quality :
- class 1 and class 2 : characterized a location in which the cortical plates are thick and the volume of bone marrow is small .
- class 3 and class 4 : Relatively thin walls of cortical bone will border sites that belong to class 3 and class 4, while the amount of cancellous bone , including trabeculae of lamellar bone and marrow is large .
- Quality 1 to 4: less cortical bone, more bundle bone present
- Quality 1: thick and resistant bone – very good for dentures, not very good for implants – there is no proper blood supply to the area so you might have problems with osseointegration
Vs
- Quality 4: it is so soft so there is no primary stability so when you are placing an implant you might need to stop before placing the correct size, there is a lot of bleeding upon working
Discuss the clinical ramifications of tooth extraction in each of the pictures in Fig. 3-10
a) Very thin buccal plate due to facial positioning of the tooth, which will cause fast resorption leading to probably the disappearance of it.
(b) In this case the cortical plated of alveolar processes are continuous with the bone that lines the socket, so by extracting the tooth there will be no plate left. Also the basal bone is very small. There will be a problem if implants are to be placed later on.
(c) In the xray we can see how the normal orientation of the tooth can affect the way the bone resorbs.
(d) No buccal bone can be detected, leading to esthetic problems.
What is the clinical significance of the pattern of extra-alveolar process healing? Discuss replacing the missing tooth/ teeth with implants/ FPDs.
(Use Fig. 3-26 to help answer the question).
- The resorption of the buccal bone wall is more pronounced than the resorption of the lingual/ palatal wall and hence the center of the ridge will move in a lingual/palatal direction
- This should be taken into consideration during implant placement, due to the possible lingual movement of the ridge, leading to possible dehiscence or making it possible for the implant to be revealed.
- This should be also taken into consideration during FDP placement, as replacement of a missing pontic should allow enough time for the socket to heal prior to FDP placement in order for good adaptation of the gingiva to be achieved.
