(DD13-14) Prostho 02 (DD13-14) Prostho 02 PDF

Preview

Summary

complete denturesThe shape and amount of the distobuccal extension of a complete mandibu- lar edentulous impression is determined during border molding by t h e: ramus of th e mandible position and action of t h e masseter muscle lateral pterygoid muscle tone of th e buccinator muscle size and locat...

Description

complete dentures The shape and amount of the distobuccal extension of a complete mandibular edentulous impression is determine d during border molding by the:

• ramus of the mandible • position and action of the masseter muscle • lateral pterygoid muscle • tone of the buccinator muscle • size and location of the buccal frena

1 copyright

PROSTHODONTICS

2013-2014 - Dental Decks

• position and action of the masseter muscle When border molding a mandibular custom tray that will be used for a final denture impression: • The distobucca l extension is determined by the position and action of the masseter muscle. • The distolingual extension is limited by the action of the superio r constricto r muscle. • buccal vestibule: proper extension into this area provides the best support for the mandibular denture. This is referred to as the buccal shelf. • Lingual the proper borders must be established with movements of the tongue when border molding. The genioglossus muscle influences the length of the flange during normal movements of the tongue. • The muscle will elevate the mandibular anterior labial area unless this border is established by accurate border molding. • The retromolar pad : marks the distal termination of edentulous ridge structure needs to be covered for support and retention. • The mylohyoid area: the flange in this area must accommodate the movement of the mylohyoid muscle in swallowing. • The area : this area is limited posteriorly by the action of the palatoglossus muscle and inferiorly by the lingual slip of th e superior constrictor muscle. Remember: The palatoglossus, superior pharyngeal constrictor, mylohyoid, and genioglossus muscles are influential in molding the lingual border of the mandibular impression for an edentulous patient. Important: Note: The custom tray for a final mandibular or maxillary complete denture impression should have a spacer with stops to insure tha t the tray will be seated in proper relationship to the arch and that there will be adequate room for the impressio n material. The space is created with wax covered by aluminum foil over the master cast prior to forming the tray. The primary difference between border moldin g with a ZOE impression material and border molding with modeling plastic is that the ZOE impression material must be border molde d durin g one insertion and within the setting time of the material — as opposed to two insertions with modeling compound.

complete dentures The primary reasons fo r obtaining the most extensive mandibular complete denture are:

coverage for a

> to increase the capacity of underlying structures to withstand the stress due to biting force and to improve appearance • to provide balanced occlusion and to increase tongue space • to increase the capacity of the underlying structures to withstand the stress due to biting force and to increase the effectiveness of the seal • to improve retention and to increase tongue space

2 Decks

complete dentures Immediate dentures should be scheduled for relines at:

• 1 month and 3 months post extraction • 4 months and 7 months post extraction • 5 months and

months post extraction

• 1 year and 2 years post extraction

3 copyright © 2013-2014- Dental Decks

PROSTHODONTICS

• t o increase the capacit y of the underlying structures to withstan d the stress due to biting force and t o increase th e effectiveness of the seal *** Key point — of the peripheral border of a complete mandibular denture decreases tissue-bearing surfaces, thereby . Marked ridge resorption will occur if a mandibular complete denture base terminates short o f the retromolar pad.

The active border molding performed by the lips, cheeks, and tongue determines the peripheral areas of a mandibular arch, thus establishing maximal base bone coverage. Limiting structures of the mandibular denture: • Mandibular anterior labial area: action of the mentali s muscle and the fold determines the extension of the denture flange in this area. • Mandibular labial this band of fibrous connective tissue helps attach The size of this structure limits the extension of the denture border, the thickness of the denture base, and • Buccal vestibule: is influenced by the buccinator muscle which has muscle fibers that run in an oblique direction and therefore have little displacing action. • Masseter area: the denture is limited in a lateral direction by the action of the masseter muscle. • Retromolar pad: marks the distal termination of the edentulous ridge structure and needs to be covered for support and retention. By doing this the integrity of bone in thi s area is maintained and allows for support. • Lingual frenum: the proper borders must be established with movements of the tongue when border molding. The genioglossu s muscle influences the lengt h of the flange durin g normal movements o f th e tongue. • Sublingual gland area: maximum extension desired without overextension. • Mylohyoid area: the flange in this area must accommodate the movement of the mylohyoid muscle in swallowing. • Retromylohyoid area: this area is limited posteriorly by the action of the palatoglossus muscle and interiorly by the lingual slip of the superior constrictor muscle. If these muscles are impinged upon,

• 5 months and

months post extraction

Recontouring of the healing ridge progresses rapidly for four to six months and does not become stable in form until 10 -1 2 months post extraction. Due to this, immediate dentures become progressively more ill-fitting. They should be relined five months and ten months after delivery in order to compensate for contour changes . Note: This is a general timeline; each case needs to be evaluated monthly and, if necessary, performed. A reline is indicated on any denture whe n the diagnostic information indicates that a line will effectively solve the patient's chief complaint — when the denture base adaptation is the major defec t in the prosthesis . A reline is contraindicated when there is excessive overclosure of the vertical dimension — a large decrease in vertical dimension. In this case, new dentures are indicated at the proper vertical dimension. Note:

complete dentures All new dentures should be evaluated:

3 hours after delivery hours after delivery 24 hours after delivery > 48 hours after delivery

copyright ©

- De nt al Decks

PROSTHODONTICS

complete dentures Posterior teeth that are set edg e to edge may cause:

• gagging

• cheek biting • reduced taste • speech aberrations

copyright €> 2013-2014 - Dental Decks

PROSTHODONTICS

• 24 hours after delivery This is done for the purpose of correcting undetected errors and adjusting areas that are causing tissue trauma. Tissue trauma attributed to denture function manifests as hyperemia, inflammation, ulceration, and pain. The basic sequence of the clinical procedure for a 24 hour recall appointment is: Remove the dentures from the mouth. 2. Thoroughly examine the mouth. 3. As k the patient about the areas of tissue trauma which have been observed. 4. Permit the patient to describe additional complaints. *** After collecting all of the diagnostic information, the dentist can determine the source of the problem and the cure. Remember: During the first few days following the insertion of complete dentures, the patient should expect some difficulty in masticatin g most foods and excessive saliva — which is due to Over time this will subside and become normal. Important:

cheek biting

Common Causes of Chee k Biting with New Dentures Cause

Treatment

Posterior teeth edge to edge

Reduce the facial surfaces of mandibular molars to create proper horizontal overlap

Inadequate vertical dimension of occlusion

Reline at corrected VDO, patient remount, fabricate new denture

Biting corners of the mouth

Reset canines/premolars

Lip biting may be due to reduced muscle tone a large anterior horizontal overlap. 2. Tongue biting may b e caused by having posterior teeth too far lingually.

complete dentures Maxillary anterior teeth in a complete denture are usually arranged:

facial • lingual

the ridge the ridge

• exactly over the ridge

6 copyright © 2013-2014 - Dental Decks

PROSTHODONTICS

complete dentures A patient who wears a complete maxillary denture complains of a burning sensation in the palatal area of his/her mouth. This i s indicative of too much pressure being exerted b y the dentur e on the:

incisive foramen palatal mucosa notch posterior palatal seal

7 copyright ©

PROSTHODONTICS

- Dental Decks

• facial t o th e ridge - for best esthetics

Setting anterior teeth directly over the ridge usually causes poor esthetics of dentures. Also, it is important to have accurate adaptation of the border seal and adequate bulk of the maxillary facial flange for good esthetics. Vertical dimension of occlusion affects the lip support as well.

Important: The long axes of the maxillary central incisors should be perpendicular to the occlusal plane; the long axes of the maxillary lateral incisors should have an asymmetric mesiodistal inclination. Remember: Maxillary central incisors are the most important teeth in terms of esthetics. Their placement controls the midline, speaking line, lip support and smiling line composition. Note:

Some of the common errors in the arrangement of teeth include: • Setting mandibula r anterior teeth too far forward to meet the maxillary teeth • Failure t o make canines th e turning point of the arch • Setting the mandibular firs t premolar s buccal to the canines • Establishing the occlusal plane by an arbitrary line on the face • Not rotating anterior teeth enough to give an adequately narrowe r effect

• incisive foramen

Notes

A burning sensation in the mandibular anterior area is cause d by pressure on the mental foramen. 2. A patient having trouble swallowing may have insufficient interocclusal space — decreased freeway space caused by excessive vertical dimension of occlusion.

Learning to chew satisfactorily with new dentures requires at least 6-8 weeks. This time is spent on establishing new memory patterns for both facial and masticatory muscles. Residual ridges can be ruined by the use of denture adhesives and Therefore, patients should be specifically warned about their uses. These agents can modify the position of the denture on the ridge and as a result, change both vertical and centric relations.

complete dentures The treatment plan for a patient indicates that both mandibular and maxillary immediate dentures are to be fabricated. The ideal way to do this is:

• fabricate the maxillary immediate denture first • fabricate th e mandibular immediate denture first • fabricate the maxillary and mandibular immediate dentures at the same time

8 Decks

PROSTHODONTICS

complete dentures The step in the treatment of abused tissues in a patient with existing dentures is to:

• fabricate a new set of dentures • reline the dentures • educate the patient • excise the abused tissues

9 copyright © 2013-2014 - Dental Decks

PROSTHODONTICS

• fabricate th e maxillary and mandibular immediat e dentures at the same time

The main reason for this is to avoid setting the maxillary teeth to the likely malpositions of the remaining mandibular teeth. Important: If the master casts are altered in an immediate denture procedure (e.g., elimination of gross undercuts), it is advisable to construct a second denture base that is transparent (called a surgical stent or template). This surgical stent is placed over the ridge after the teeth are extracted. Pressure points and undercut s are readily visible and surgical ridge correction can be performed. Remember: The duplication of the master cast used for the construction of the surgical template to be used at the time of immediate denture insertion is best made after wax elimination and after the cast is trimmed. Note:

• educate the patient Important: The patient should understand both the cause of the tissue deterioration and the eventual outcome if the process is not arrested. Treatment plan for tissue recovery from abused tissues: • Educate the patient • Remove the dentures: at least for 24 hours or until the tissues return t o normal size, shape, color, consistency, and texture. Note: If the constant wear of unacceptable dentures is the cause of the tissue abuse, the most efficient preliminary treatment is removal of the dentures. However, business and social commitments may not permit removal for extended periods. In such patients, resilient tissue conditioning materials may be used to assist i n th e tissue recovery program. • Have the patient clean the dentures: with a soft brush and no abrasive agents. They should be instructed to soak the dentures for at least 30 minutes in a commercially available denture disinfectant solution. •

• Resilient tissue conditioning materials may be needed t o assist in the tissue recovery program. Other procedures recommended as aids in the treatment of abused tissues include massage and warm saline rinses.

complete dentures The most important

of an overdenture (root-retained denture) is:

• the psychological comfort of avoiding the loss of all teeth • the continuous functional feedback tors in the periodontal membrane

the neuromuscular system from propriocep-

• the preservation of the alveolar ridge • the improved support and stability for the denture • the increased retention of the denture

10 copyright ©

- Dental Decks

PROSTHODONTICS

complete dentures The incisal edges of the maxillar y anterior teeth should just touch line of the lower lip when enunciating which sound (s)l

wet/dry

• linguoalveolar sounds or sibilants (such as s, z, sh, fricatives or labiodental sounds (such as f, v, > b, p, and m sounds linguodental sounds (such as this, that, or those)

copyright © 2013-2014 - Dental Decks

PROSTHODONTICS

• th e preservation of the alveola r ridg e

The overdenture is a denture whose bas e is constructed to cover all of the existing residual ridge and selected roots. Retained roots help to prevent resorption of the alveolar ridges. These roots also improve retention and afford the patient some proprioceptive sense of "naturalness" in function of the dentures. It is not always necessary to cover a roo t beneath an overdenture, however, if a root is not covered, the exposed surfaces are highly susceptible to decay. The oral hygiene of the patient must be impeccable to prevent the decay o f these roots. Note: . Important: The general rule for retained root tips with no radiolucency and the cortical margin of bone intact is that they can remain in place; however, the patient should be informed of their presence. They should be removed if the cortical plate is perforated and/or the PDL or radiolucent area is getting larger.

• fricatives or labiodental sounds (such as f, v,

Speech sounds i n the complete denture patient: • Fricative or labiodental sounds (f, v, are formed between the maxillary incisors contacting the wet/dry lip line of the mandibular lip. Note: These sounds help determine the position of the incisal edges of the maxillary anterior teeth. andj): are made with the tip of the • Linguoalveolar sounds or sibilants (s, z, sh, tongue and the most anterior part of the palate or lingual surface of the teeth. Note: These sounds help determine the vertical length and overlap of the anterior teeth. Important:

• Linguodental sounds (this, that, and those): the tip of the tongue should protrude slightly between the maxillary and mandibular anterior teeth. Note: These sounds help determine the labiolingual position of the anterior teeth. • The b, p, and sounds: are made by contact of the lips. Note: Insufficient lip support by th e teeth or the labial flange can affect the production of these sounds. Note:

Important: To evaluate vertical dimension, have the patient pronounce the s sound; the interincisal separation should be This is known as the closest speaking space. Remember: •

complete dentures The primary role of anterior teeth on a denture is:

• to incise food • occlusion • esthetics • stability of the denture

12

PROSTHODONTICS

A patient has wor n a complete maxillar y denture for 8 years against mandibula the mandibular teeth are missing). She com-

13 copyright © 2013-2014- Dental Decks

• esthetics Spaces, lap pi ng , rotation, and color chan ge s can b e judiciously use d t o create a natural appearance. No te : Proper lip support is provided by the facial surfaces of teet h and simulated atta ched g ing iv a. Setting the anterior teeth either too far lingually or facially to satisfy esthetic concerns should not be done. When selec ting teeth, pre-extra ction records are very valuable.

The outlin e of anterior teeth should harmonize with the form of the face: • Convex profile faces should hav e a similarly conve x labial surface of anterio r teeth • Broader co ntact a re as of teeth look m o re natu ral on dentures as they s ee m mor e com patible with advanced age

Note: In general, functional needs overshadow those of esthetics when selecting posterior teeth.

• a lack of posterior occlusion These signs and symptoms are caused by a lack of posterior occlusion. Important: A patient wearing a maxillary complete denture and a mandibular bilateral distal-extension removable partial may show: • Note: When a complete maxillary denture opposes natural mandibular anterior teeth, the maxillary anterior ridge often becomes very flabby. Remember: The best impression technique for an edentulous patient with loose, hyperplastic tissue in the maxillary anterior region is to 1.

. Surfaces of a denture that play a part in retention: • Intimate contact of the denture base and its basal seat • Teeth: no occlusal prematurities to break retention • Design of the labial, buccal, and lingual polished surfaces: configuration hannonious with forces generated by the tongue and musculature 4. Factors that influence denture surface: • Adhesion: saliva to denture and to tissues — primary retentive force • Cohesion (the attraction of molecules for each other) depends on: the area covered and the type of saliva (i.e., thick, ropy — unfavorable; thin, watery — better retention) • Atmospheric pressure : proportionate to area covered and depends on peripheral seal • Mechanical: ridge size, shape, and interridge distance

complete dentures The prim ar y indicator of the accuracy o f border mo lding is:

adequate coverage of tray borders wit h the material used for border molding contours of th e periphery similar to the final form of th e denture stability and lack

displacement

the tray in th e mouth

uniformly thick borders of th e periphery

14 copyright ©

- Dental Decks

PROSTHODONTICS

complete dentures You are in t he process of making a complete maxillary denture for a patient. Which of th e following structure (s) will be the secondary support area (s)l

• residual ridges • palatal rugae • incisive papilla • maxillary tuberosity • buccal vestibule

15 copyright ©

PROSTHODONTICS

- Dental Decks

• stability and lack of displacement of t...