Tooth Supported Dentures

Question 1

Why not extract all remaining teeth and plan a complete denture?

Answer 1

The teeth and the alveolar bone are closely interlinked. Without the teeth the alveolar bone tends to atrophy and resorb. The longer the teeth remain in the alveolar bone the longer it is preserved.

Question 2

Why not leave the remaining teeth and plan an RPD?

Answer 2

Over a period of time mobility and periodontal breakdown could ensue resulting in failure of the abutments.

Question 3

Why shorten the teeth?

Answer 3

Shortening the natural tooth changes the crown root ratio. This reduces the lateral stresses. It also reduces lever action on the tooth. The load is now in a more occlusal direction which is better tolerated by the tooth.

The complete denture resting on these shortened teeth exerts largely vertical forces directed towards the bone which are better tolerated by the teeth (fig. 24-2). Reducing the crown-root ratio also forms the basis of using mobile teeth which otherwise would have been indicated for extraction. Reducing the crown-root ratio reduces the mobility of these teeth and improves their prognosis.

Question 4

What’s t.s.d?

Answer 4

Any removable dental prosthesis that covers and rests on one or more remaining natural teeth, the roots of natural teeth, and/or dental implants; a dental prosthesis that covers and is partially supported by natural teeth, natural tooth roots, and/or dental implants (GPT-7).

Question 5

What’s classification of t.s.d? Based on abatement preparation?

Answer 5

1. Noncoping
   a. With endodontic therapy
   b. Without endodontic therapy
2. Coping
   a. With endodontic therapy (short coping)
   b. Without endodontic therapy (long coping)
3. Attachments

Question 6

What’s classification of t.s.d? Based on type of overdenture?

Answer 6

1. Immediate over denture
2. Transitional over denture
3. Remote over denture

Question 7

Talk about non coping a abutment in t.s.d

Answer 7

Noncoping abutments with endodontic treatment Most teeth require endodontic therapy because of a lack of interocclusal space. Selected root abutments are reduced to a coronal height of 2 to 3 mm and then contoured to a convex or dome shaped surface. The root canal access opening is restored with amalgam or composite.

Noncoping abutment without endodontic treatment This type is given only if there is sufficient interocclusal space. The pulp should have receded sufficiently so that the reduced teeth are not sensitive. It is usually indicated in patients with partial anodontia and severe attrition.

Question 8

What’s coping a abutments? Short and long coping

Answer 8

Coping abutments A coping is a thin covering. The abutment teeth may be covered with copings to give better protection against caries. Cast metal copings with dome shaped surfaces and chamfer finish lines at the gingival margins are made and cemented.

Short cast copings (fig. 24-4) These are 2 to 3 mm long and normally require endodontic treatment because of the risk of pulp exposure. The coping is attached by means of a post in the root canal. The canal should therefore be obturated with gutta percha (instead of silver points).

Long cast copings These are about 5 to 8 mm long and are given in an attempt to avoid endodontic treatment. They also require greater bone support.

Question 9

What’s Abutments with retentive devices in t.s.dd?

Answer 9

In cases where increased retention is required for the denture, special retentive devices may be attached to the abutment and to the inner surface of the denture.

Question 10

What’s Immediate, transitional and remote overdentures

Answer 10

The immediate overdenture is constructed for insertion immediately after extraction of some natural teeth.

A transitional overdenture is obtained by converting an existing removable partial denture into an overdenture.

The remote overdenture is constructed after the extraction of the teeth, endodontic therapy, cast copings or any other procedure.

Question 11

What are INDICATIONS FOR OVERDENTURES

Answer 11

1. Patients with few remaining natural teeth (fig. 24-5)
2. Patients with poor prognosis for routine complete dentures.
   a. High palatal vault
   b. Xerostomia
   c. Poor mandibular ridges
   d. When high rate of resorption is expected
   e. When opposing natural teeth are present
   f. Smaller dental arches
3. Patients with congenital or acquired intraoral defects.
   a. Partial anodontia
   b. Cleft palate
   c. Microdontia
   d. Amelogenesis imperfect
4. In case of severe attrition, vertical height can be restored with an overdenture.
5. Very young patients facing total extraction.
6. Patients with few remaining natural teeth
7. Low caries index and good oral hygiene.

Question 12

What are contraindications for over denture?

Answer 12

1. High caries index and poor oral hygiene
2. When the abutments have a doubtful prognosis

When endodontic treatment is not possible When periodontal therapy and reduction of crown-root ratio does not improve periodontal health.

3. Failure to establish a sufficient zone of attached gingiva.
4. Uncooperative, terminally ill, or senile patients.

Question 13

What are advantages of over denture

Answer 13

1. Preservation of the alveolar bone. Presence of the abutment teeth reduce resorption.
2. Preservation of the proprioceptive response. Oral function and feeling is improved because of the proprioceptive feedback from receptors in the root.
3. Improved support because of the abutment teeth.
4. Improved retention. Retention devises can be attached to the abutment teeth when increased retention is needed.
5. Less psycologic trauma as patients are able to retain their original teeth.
6. Can be converted to a routine complete denture in case of abutment failure

Question 14

What are disadvantages of overdenture?

Answer 14

1. High risk of caries especially for the noncoping abutments due to coverage of the teeth by the denture
2. Risk of periodontal problems due to improper care by the patient
3. High initial cost due to the castings, precision attachments, preceding endodontics, periodontal and other therapies.
4. Long bony undercuts are often found near the abutment teeth. They cause many problems like
   a. Tissue injury during insertion and removal
   b. To avoid the undercuts the flanges are sometimes shortened which can reduce the peripheral seal
   c. Blockage of the undercuts results in a flange placed away from the tissues. This can result in esthetic problems due to the bulging of the lips. Spaces between the tissues and the flange can also create a food trap
5. Tooth arrangement is difficult in some cases because of the reduced interocclusal distance.

Question 15

Talk about Endo and perio treatment in In tooth supported complete denture

Answer 15

ENDODONTIC THERAPY It is beneficial to treat the tooth endodontically to allow for sufficient reduction of the crown root ratio. Therefore it is important to determine of successful endodontics can be done. Single rooted teeth like canines with single patent canals are good candidates. However, multirooted teeth may also be used.

PERIODONTAL THERAPY Periodontal therapy includes elimination of inflammation, pockets, and bone defects. The reduction of crown height considerably reduces mobility, including grade I, most grade 2 and sometimes even grade 3 mobility.

Attached gingival zone A common problem encountered is the presence of an insufficient zone of attached gingiva around the abutment teeth.

This is necessary

1. To reduce the incidence of inflammation
2. To reduce the potential for pocket formation

The zone of attached gingiva can be increased by means of a graft - either a free gingival or an apically repositioned graft.

Question 16

Talk about fluoride therapy and amalgam plug in In tooth supported complete denture

Answer 16

FLUORIDE THERAPY In cases where cast copings are not going to be provided, the dentist must make sure that the tooth structure is properly smoothed and polished after the remodelling. Secondary caries is a major cause for concern in unprotected teeth. Research has shown that regular fluoride application during routine office visits, in addition to regular home care considerably reduced the incidence of caries.

AMALGAM PLUG Some operators place an amalgam restoration into the root canal after the endodontic therapy. The tooth is sectioned slightly above the gingival margin. Amalgam is condesed into the exposed root canal. The amalgam restoration along with the exposed tooth structure is finished and polished.

Question 17

Talk about IMPRESSION AND CONSTRUCTION OF OVERDENTURE

Answer 17

After the cementation of the copings, impressions are made for the construction of the denture.

Cast metal base or frame Some dentists construct a metal base, prior to denture construction. This reinforces the denture and increases its strength and resistance to fracture.

Cast housing A metal housing or receptacle may be provided within the denture if only acrylic is to be used.

One of the problems faced during the overdenture construction is the reduced interocclusal clearance especially in the region of the abutments. A great deal of grinding may be required to fit the teeth in the available space during teeth arrangement.

Question 18

Talk about -RETENTION OF AN OVERDENTURE

Answer 18

RETENTION OF AN OVERDENTURE

In the case of large well formed ridges, overdentures may be constructed with or without retentive devices. However, in case increased retention is required they may be constructed with embedded retentive devices.

There are many types of retentive devices currently being used.

1. Precision attachments
   a. Stud attachments
   b. Bar and clip attachments
2. Magnets

Question 19

Talk about ATTACHMENTS in RETENTION OF AN OVERDENTURE it’s indications and disadvantages.

Answer 19

ATTACHMENTS Many overdentures are secured to the abutments using attachments. These are tiny devices (usually prefabricated) with a male and female portion.

One part is joined (soldered or joined by casting) to the coping and the other to the overdenture. To use attachments, the patient should have good bone support and adequate interocclusal clearance. Magnets have also been used to provide retention. Some of the attachments are rigidly connected, whereas others have some kind of a stress breaking effect (resilient). The resilient ones reduce the transfer of harmful stresses to the abutment teeth.

Indications Precision attachments increase the stress on the abutments as well as increase the cost of the overdentures. For this reason the following factors are absolutely vital

1. Low caries index
2. Improved periodontal health
3. Good oral hygeine
4. Greater bone support

Disadvantages

1. More expensive
2. Requires more time to construct
3. Difficult to correct in case of failure.

Question 20

Talk about parts of stud attachments and it’s classification

Answer 20

Parts The attachment consist of 2 basic parts

1. A male portion or stud
2. A female portion or housing or receptacle

Usually the male portion is soldered on to the abutment tooth. The female portion is incorporated into the denture. Retention is obtained when the female housing engages the male stud. (In the Zest anchor attachment (24-7), this relation is reversed - the male portion in the denture engages the female receptacle which is placed within the root canal.) In some systems the male stud has a soldering base from which it can be detached. This allows them to be replaceable in case of damage or wear.

Classification They may classified as

1. Resilient or
2. Nonresilient (rigid)

Nonresilient The female part is rigidly attached to the male portion. This type places greater stress on the abutments.

Resilient This type is designed to provide some amount of controlled movement between the male and female portion. This dissipates some of the stresses transferred to the abutments.

Question 21

Talk about bar and clip attachments and its functions

Answer 21

Bar and clip attachments The typical bar attachment consists of a bar connecting two or more abutments (fig 24-9. A & B), e.g. a bar joining or connecting two canine copings. Joining the two abutments provides a splinting action. A metal or plastic clip fixed on the tissue side of the denture attaches it to the denture (fig. 24-9.C).

Function

1. Splinting of the abutments
2. Allows rotational movement allowing the denture to take more support from the ridges (toothtissue borne).
3. Provides the regular functions of retention and support like the earlier mentioned stud attachments.

Question 22

Talk about classification of Bar and clip attachments

Answer 22

Classification The bar attachment can also function like a rigid stud when designed in a certain way. These are known as bar units.

Thus there are two types of bar attachments

1. Bar joints - Permits rotational movement (fig. 24-9 A to C & fig 24-10).
2. Bar unit - Rigid fixation. Permits no movement (fig. 24-11).

The bar joint is generally used as a splint connecting the abutments together, whereas the bar unit is placed as a single unit on the abutment teeth (like a stud attachment).

There are many bar attachments available. Among the famous ones are the Baker clip, Hader and the Dolder bar etc.

The bars are attached to the abutment copings by soldering.

Question 23

Talk a bout magnets in over denture

Answer 23

Special magnets are available (fig. 24-12) which can be attached to the overdenture abutments. The mangets attract small metal plates embedded in the overdenture. The magnets generate forces of attraction sufficient to provide retention to the ovedenture.