Selasa, 27 September 2011

Functional appliances-Orthodontic Lecture note

Functional Appliances Definition
  • Appliances which change the position of mandible as to transmit the forces generated by stretching the muscles, fascia and periosteum to the dentition and underlying skeletal structures are called as functional appliances.
  • Functional appliances are mainly based on functional matrix theory by Moss (1968).
  • According to that theory mandibular growth can be altered by functional alteration of the rest position of the mandible.

History of development of functional appliances
• Robin 1902- monobloc
• Andresen 1908- Activator
• Herbst 1934- Herbst
• Balters 1960- Bionator
• Bimler 1964 – Bimler
• Frankel 1967- Frankel
• Clark 1977-Twin Block

Classification of Functional appliances
Two types
  • Removable
  •   Fixed

Removable functional appliences

Activator type
  • Twin block
  • Andreson
  • Bionator
  • Harvold

Frankel type
Eg: Frankel appliance

Fixed functional appliences
Eg: Herbst appliance

Twin block appliance

Two blocks
·         Upper block
·         Lower block

Upper block
  • Two adam’s clasps
  • Molar capping
  • U loop labial bow

Lower block
  • Two adam’s clasps
  • Molar capping
  • Ball clasps/Cleats

Andresen appliance
·         Mono block
·         Base plate covering the palate and lingual aspect of lower ridge
·         Labial bow anterior to the upper incisors
·         Buccal faceting

Bionater appliance

·         Light appliance with minimal bulk
·         Lingual horse shoe of acrylic
·         Palatal spring which is shaped like a reversed coffin spring
·         Labial bow is extended distally


Frankel appliance

Flexible appliance more wire components less acrylicthree main types

Herbst appliance

Mode of action of functional appliances
Mainly it functions on anterior growth rotation of the mandible. Anterior growth rotation is the rotation which grows the mandible in antero superior direction.whn patient wears the functional appliance mandible tent to draw forward, which in turn increases the pulling of muscles and ligaments acting on mandible. As a result anterior growth rotation gets activated. Finally by activating the u loop labial bow upper incisors will be retroclined.
  • Skeletal effects
  • Dentoalveolar effects
  • Soft tissue effects

Skeletal effects
Many studies have found an apparent increase in mandibular growth of 1-2mm during active treatment.
Restraint of forward growth of the maxilla.

Dentoalvelar effects
·         Inhibition of downwards and forwards eruption of maxillary teeth.
·         Retroclination of upper incisors
·         Proclination of lower incisors

Effects on soft tissues
Removal of lip trap and improved lip competence
Removal of adaptive tongue activity
Removal of soft tissue pressures from the cheeks and lips

Clinical use

Classic one stage treatment
Some patients can be treated to an extremely acceptable result with functional appliences
Such cases usually have a mild skeletal discrepancy, proclined upper incisors and no dental crowding.

Interceptive treatment
Effective at reducing the relative prominence of proclined upper incisors, which are particularly susceptible to dentoalveolar trauma

Two stage treatment
Improving the anteroposterior relationship with anchorage reinforcement at the beginning  of fixed appliance treatment

Compromise treatment
Some patients who are unstable for fixed appliences (such as physically handicapped patients) may gain some benefit, both occlusally and facially, from functional appliances.

Timing of treatment
Pubertal growth spurt
·         Male                      Age 14 + 2 years
·         Female                 Age 12+ 2 years

Case selection for the Functional appliance
  1. Patient should be on pubertal growth spurt
  2. Patient should be well motivated
  3. Moderate to severe skeletal discrepancy
  4. Posterior positioned mandible
  5. Well aligned arches
  6. Average or low FMPA angle
  7. Facial profile improves when mandible posture forward(chin not promonent)

Appliance management
  • Patient motivation
  • Records
  • Impression and occlusal registration
  • Bite registration
  • Fitting of appliance
  • Instructions to the patient
  • Assesment of the progress
  • Reactivation of the appliance
  • Retention

Senin, 26 September 2011

Facts about Amalgum and Mercury hygiene

Amalgum is alloy mercury with another metal or metals.
Mercury is liquid at room tempreture and freezing point is -390c.
It can readily undergo amalgamation reaction with metals such as silver, tin and copper.
High copper amalgams has significantly improved clinical performance of amalgam.

Composition of amalgam
  • Ag           58-70%
  • Sn           18-30%
  • Cu           12-22%
  • Zn           0.5-1%
  • Palladium

Mercury is used to; Bind the metals together and to provide a strong, hard durable filling.mercury is the only element that will bind these metals together in such a way that can be easily manipulated into a cavity.
Zinc; reduce incidence of fracture of margins by 45% and act as a scavenger during production of alloy (react with oxygen and form stag which can easily removed.
Zn free amalgams are made in intert atmosphere to prevent oxidation during melting.Zn containing amalgams can be contaminated with moisture during condensation.

Zn           +             O2                  =            ZnO        +             H2

Liberated hydrogen can cause delayed expansion of amalgam.

Classification of amalgam
  • Conventional amalgam-Less than 6% copper
  • Copper enriched amalgams-6-30% copper

Mercury in dental amalgam safe?
Dental amalgam is a safe and effective restorative material
Dental amalgam contains elemental mercury combined with other metals such as silver, copper, tin and zinc, which forms a safe, stable cavity-filling material. It's important to note that dental amalgam has entirely different properties than mercury by itself.

Mercury in dental amalgam is not poisonous. When mercury is combined with other materials in dental amalgam, its chemical nature changes. so it is essentially harmless. 
The amount released in the mouth under the pressure of chewing and grinding is extremely small (1-3 micrograms) and no cause for alarm.
In fact, it is less than what patients are exposed to in food, air, and water (5-7 micrograms a day)
Ongoing scientific studies conducted over the past 100 years continue to prove that amalgam is not harmful.
Claims of diseases caused by mercury in amalgam are anecdotal, as are claims of miraculous cures achieved by removing amalgam. These claims have not been proven scientifically

Why do dentists use dental amalgams?
Dental amalgam has withstood the test of time, which is why it is the material of choice. It has a 150-year proven track record and is still one of the:

·         safest

·         durable 

·         Least expensive materials to a fill a cavity. 
It is estimated that more than,1 billion amalgam restorations are placed annually.
Dentists use dental amalgams because, It is easier to work with than other alternatives.

Some patients prefer dental amalgam to other alternatives because of its
safety, cost-effectiveness, and ability to be placed in the tooth cavity quickly
Why don't dentists use alternativesto amalgam?
Alternatives to amalgam:

·         cast gold restorations

·         porcelain

·         Composite resins are more costly. 

Gold and porcelain restorations take longer to make and can require two appointments. Composite resins, or white fillings, are esthetically appealing, but require a longer time to place the restoration. It should also be known that these materials, with the exception of gold, are not as durable as amalgam

What about patients allergic to mercury?
The incidence of allergy to mercury is far less than one percent of the population.
People suspected of having an allergy to mercury should receive tests by qualified physicians, and, when necessary, seek appropriate alternatives.

Dentists are using pre-mixed capsules, which reduce the chance of mercury spills.
And newer, more advanced dental amalgams are containing smaller amounts of mercury than before.
Because dental staff are exposed to mercury more often, one would expect dental personnel to have higher rates of neurological diseases, such as multiple sclerosis. They do not.

What are other sources of mercury?
Mercury can be found in:
·         Air
·         Food
·         Water
We are exposed to higher levels of mercury from these sources than from a mouthful of amalgam.

Are amalgam dental restorations containing mercury safe for children?
Children who received dental restorative treatment with amalgam did  not score significantly better or worse on neurobehavioral and  neuropsychological assessments than children who received resin  composite material. Children who receive restoration with resin may be more likely to need additional treatment. Studies evaluating outcomes for longer than 5 to 7 years are needed.

Dental mercury hygiene
  • Alert-during training we need to observe good Hg hygiene practice
  • Ventilation-fresh air exchanges AC plants act as Hg reservoirs. Therefore filters should bee replaced with time.
  • Surgery atmosphere should be checked periodically
  • Do not carpet the floor. Sheet flooring up to 10cm of wall.
  •  Hg storage-Unbreakable, tightly sealed, and store away from heat.
  • Use single use capsule sealed during amalgamation
  • Avoid removal of excess Hg and use correct Hg: Alloy ratio
  • Use a totally enclosed amalgamator
  • Hg dispensers handle with care and heck regularly for any leaks
  • Check orifice for residual Hg.
  • Hg should not touch with bare hands
  • All amalgam scrap and Hg stored in a tight container and discard under radiographic fixer solution.
  • Spilled Hg immediately cleaned and placed in a scrap jar
  • Do not heat Hg or amalgam and instruments, clean them before heat sterilization
  • Do not use ultrasonic amalgam condensers
  • Remove old amalgams and polish under copious air water spray and high volume evacuation exhaust outside the surgery
  • Wear a mask
  • All the abrasions and cuts in the skin should be covered prior to handling the amalgam
  • Disposable material contaminated with amalgam disposed properly
  • Waste water systems-place Hg traps
  • Skin contaminated with Hg should washed thoroughly with soap and water
  • Do not eat, drink, smoke inside the surgery
  • If Hg toxicity problem suspected-urine analysis done for Hg.

Sabtu, 24 September 2011

Lecture notes on Prosthetics Dentistry (Prosthodontics)

History taking for construction of a partial or complete denture Patient complain 

1.   Appearance: Aesthetics
2.   Function: to restore function

Previous denture wearer
1.   Pain
2.   Retching
3.   Problems eating with prosthesis

Denture history
1.   New denture wearer
2.   Old denture wearer
3.   Age of denture when was first worn
4.   How many sets of denture worn
5.   Haterial of denture

General dental history 
1.    Number of Missing teeth  in upper arch
2.    Missing teeth in lower arch
3.    Oral hygiene condition
4.    Alveolar bone status
5.    Upper and lower arches
6.    Any areas of bone resroption
7.    Periodontal problems and gum recession
8.    Number of filled  teeth
9.    Any crowns present
11. Orthodontic therapy ,
12. Endodontically treated tooth
13. Splints
14. Previous treatment tried for present complaint

Medical history
Any medical condition
Anxiety and depression status of patient
History of stroke ,muscle disorders

Social history
1.   Marital status
2.   Mobility
3.   Access for treatment
4.   Drinking
5.   Smoking
6.   Job
7.   Examination

Extraoral examination
1.   TMJ positioning while closing and opening of jaw
2.   Any clicking of TMJ
3.   Masseter hypertrophy
4.   Tenderness in joint or muscle of mastioation

Facial counture
1.   Old photographs
2.   Loss of dental bulge
3.   Perioral skin wrinkling
4.   Angular cheilitis 
5.   Vertical hight
6.   Lip seal , over closure , or anterior openbite
Intra oral examination
1.   mucosa
2.   xerostomia,
3.   candida mucosal ulceration
4.   gingival hyperplasia
5.   undercuts

Periodontal health
1.   oral hygiene
2.   periodontal status
3.   mobility and drifting of remaining teeth

1.   number of carious teeth 
2.   and filled teeth , 
3.   recurrent caries

1.   skeletal classification ,
2.   competent lips ,
3.   prognathism ,
4.   overerypted teeth crowding or
5.   spacing of teeth

Endodontic status of teeth

Vital and non vital teeth
Endodontically traeated teeh

Support of edentulous area
1.   Quality of saddle area of  alveolar bone
2.   Degree of bone resorption
3.   Presence of tori , tubercle
4.   Bony or flabby ridges or muscle attachment 

Denture examination

1.   present denture or
2.   previous denture examination
3.   Examine both interiorly and
4.   extra oral exmmination

When existing denture in place examine
1.   Is the freeway space appropriate?
2.   Is the most retruded contact position registered correctly?
3.   Are the lips supported well
4.   Are both the posterior and anterior occlusal  plans in harmony
5.   Are the upper and lower dentures retentive at rest?
6.   Are the dentures stable in function?
7.   Is there any pain on occlusion?
8.   Does the patient like the appearance of denture?
9.   Can the patient articulate properly with the denture

With existing denture out of the mouth look for,

1. Is the base extension, anterior posterior, lingual and buccal appropriate
2. Is the denture Under extended  in lingal pouch and retromolar pads and on hard palate  or
3. Is the denture overextended overextended  to the external oblique ridige  of the mandible

Is the tooth position appropriate ?

Common problem includes,
1.   excessive  lingual positioning of posterior mandibular  teeth  and,
2.   excessive  labial positioning of anterior teeth

Underextension = Lower Dentures are frequently
                                  underextended In lingual pouches and retro molar pads

Upper denture    = Underextended,distally on the hard palate

Overextension    = Lower Dentures are frequently
                                   Overextended to,The external oblique ridge of mandible

Has the denture been altered since the insertion
1.   Addition
2.   Relining
3.   Repair

Is there any sign of parafunction e.g.
1.   Excessive wearing of denture = aged denture
2.   Wear facets
3.   Tongue thrust,
4.   Clenching of jaw ,
5.   eating on one side only

Radiographic Examination

Radiographic examination  of partial denture wearer,
can reveal,
1.   Periodontal bone level
2.   proximal caries
3.   Apical pathology
4.   Retained roots
5.   Unerypted teeth
6.   Ridge contour
7.   Bone height and width
8.   Anatomical features  such as the inferior alveolar canal
9.   Mental foramen , maxillary sinus TMJ anatomy

useful radiographs for prosthodontics are ,

1.   periapicals
2.   panaromics
3.   occlusal
4.   lateral cephalometrics and
5.   tomograms

Some cases require special tests and additional features of prosthodontoc examination
These are,
1.   study cast
2.   surveying
3.   full occlusal assessment
4.   diagnostic wax up

Study cast determine ,
Interarch and intra-arch relationship
Reveal overerypted and tilted teeth
Helps plan the design of saddle area
Helpful for construction of primary bases  or tray construction
Used for wax pattern
Helpful for outlining the difficult daddle area

1.   Surveying of cast is useful in areas of undercut and
2.   determine potential path of insertion ,
3.   removal or displacement of partial denture
4.   Is helpful for design of denture

Full occlusal adjustment
1.   For determination of lateral jaw movements
2.   May be required for face bow mounting of maxillary cast and
3.   The use of semiadjustable articulator
4.   Particularly useful for tooth wear and craniomandibular disorders

Diagnostic wax up
May be helpful; for evaluation of alternative design
Can help patient evaluation of options

Partial Dentures design
1.   May be in acrylic or
2.   Cobalt chrome denture

Alternative to denture
1.   Fix appliance e.g. crown & brides or
2.   Implant Or
3.   Not wearing denture at all

Preprosthetic management
1.   Any caries
2.   Endodontic treatment
3.   Periodontal trement must be controlled before any prsthodontic construction

No prosthodontic treatment for cases
1.   Less motivated
2.   No aesthetic problem
3.   No functional problem
4.   Stable occlusion or in harmony

Changes following extraction of teeth
There are 3 types of changes
1.   Facial changes
2.   Intraoral changes
3.   Psychological changes

Facial changes following extraction of tooth
1.   Loss of dental bulge
2.   Loss of lip support
3.   Witches chin
4.   Lips folds inwards
5.   And look thinner

Intraoral changes following extraction of teeth
1.   Loss of mandibulr height = 4 mm after one year
2.   9-10 mm after 25 years
3.   Loss of maxillary height is ine quarter of loss of mandibular height
4.   Decreasded masticatory performance
5.   Decreased propioceptive ability
6.   Resorption of buccal bone width

Psychological changes following tooth extraction
1.   Some people find edentulousness difficult to accept
2.   Or growing old or as a result of underline systemic disease
3.   Or lack of  self motivation and lack of interest

Complete dentures principles

"The artificial teeth should replace the denture space( space previously oocupied by   natural teeth ) approximitelt the same position number shape and size and place"

Features of complete dentures
1.   Good retention
2.   Good support
3.   Good muscle balance
4.   Good occlusal balance And
5.   stability

Complete denture Retention
1.   Retention is the resistance to displacement of a denture away from the ridge
2.   Good retention gives psychological comfort
3.   For good Retention close contact between denture and tissue

Retention of lower denture is more difficult to achieve because of the,

Mobility of mandible and floor of mouth than maxilla

Support of complete denture

Support is resting of denture on the mucosa and alveolar bone

Effective support requires
  •  Denture cover the maximum surface area  without moving or impinging on soft tissue
  •  Good tissues are the tissue resistant  to resorption  capable of taking load during function 
Tissues most capable of resisting vertical displacement should make contact with bases during function

    Different areas in complete dentures
    1.   Primary support area
    2.   Secondary support area
    3.   Areas non contributing to support
    4.   Areas to be relieved

    Primary support area is,

    Primary support area in upper denture is hard  palate

    Secondary support areas in complete dentures is,
    alveolar ridge crest

    Areas non – contributing to support,

     Denture border

    Areas to be relieved in upper complete denture construction  
    1.   Mid line suture and
    2.   incisive papilla

    Primary support area in lower denture
    1.   buccal shelf and
    2.   Pear shaped retro molar pad

    Secondary support area in lower denture,
    Lower alveolar ridge crest and
    Genial tubercles

    Areas non- contributing to support,
    Labial ridge incline

    Relief area in lower denture,
    1.   Lingual ridge incline and
    2.   mylohyoid ridge
    3.   prominent genial tubercle
    4.   prominent mental tubercle

    Muscle balance
    1.  Muscle balance is achieved when the forces of muscles of  lips , tongue , cheeks  do not dislodge the denture during functional movements of the mouth  and
    2.  When the teeth are out of contact
    3. Concave shape of denture polished surface gives a vertical seating force when buccinator contract
    4.  A thinner denture flange in the premolar region results in more free movement of the Modiolus ( the site of muscle fiber decussation from buccinator and orbicularis oris muscle)

    Muscles balance provided by muscles
    1.   Orbicularis oris = lips
    2.   Buccinator = cheek 
    3.   Tongue
    4.   Modiolous
    5.   Retromolar pad = pterygomandibular raphae

    Occlusal balance
    1.   Occlusal balance is achieved when the forces of one denture do not dislodge the other denture during functional jaw movements with the teeth in contact
    2.   This can be achieved by a balanced articulation

    1.   Is the ability of dentures to resist displacement by functional stresses.
    2.   Stability gives physiological comfort

    Design features of complete denture

    1.   Maxium extention of denture bases
    2.   Peripheral seal
    3.   Postdam
    4.   Fraena
    5.   Relief areas
    6.   Retruded contact position
    7.   Balanced articulation
    8.   Freeway space
    9.   Tooth position

    Denture faults 
    1.   Incorrect peripheral extension
    2.   Teeth set not in neutral zone
    3.   Un- balanced articulation

    Polished surface is unsatisfactory
    1.   Patient factors
    2.   Inadequate saliva
    3.   Poor ridge forms
    4.   Decreased adaptive skills

    Burning mouth.
    Sensitivity to acrylic monomer

    Speech difficulties
    1.   Difficult F, V sounds = incisors are set too far palatally
    2.   Difficulty with S, T, D sounds = incorrect palatal contour ->correct palatal contour
    3.   S becomes ‘th’ - incisors set too far palatally or palatal plate too thick

    Whistling sound produced
    Palate vault too high behind incisors

    Clicking teeth
    Due to increased occlusal vertical dimension

    Recurrent fractures of denture.
    1.   Carelessness
    2.   Notching of denture
    3.   Flabby ridges
    4.   Occlusal faults
    5.   Acrylic fatigue due to constant stressing
    6.   Flexing of denture

    Candida and denture
    1.   Use antifungals
    2.   Nystatin suspension 100,000 units /ml  or
    3.   Amphotericin suspension 100mg /ml or 2% miconazol gel
    For Complete denture Maximum extension of denture base by
     Covering the whole of the available space of denture bearing area

    In maxillary upper base,
    Posterior extension is just anterior to the line of flexure of the soft palate 

    In mandibular ( lower ) denture base,

    1.   Posteriorly  extended to the retromolar pad and
    2.    lingually to Lingual sulcus region

    Peripheral seal

    1.   Is the of contact between the mobile mucosa and the denture surface and ,
    2.   is determined at the master impression stage
    3.   Good peripheral seal is good for the retention  and stability

    Potsdam is,
    1.   A round smooth line at the junction of hard and soft palate
    2.   Aids in peripheral seal of maxillary denture

    1.   Labial frenum ,
    2.   buccal frenum,
    3.   lingual freum and
    4.   buccal frenum
    5.   A technique of impression taking is adopted to obtain fraenal relief

    Relief areas,
    1.   Small tori
    2.   Prominent mylohyoid ridge
    3.   prominent mental nerve foramen Often have to be relieved

    Retruded contact position
    1.  Complete denture should be registered in the most  retruded contact position
    2.  This is the position of the mandibular condyles in the most retruded position in the glenoid fossa
    3.  As this is the most reproduciable position

    Balanced articulation
    1.   The complete denture should have a balanced articulation
    2.   Which is the continuous contact position of upper and lower cusps
    3.   all around dental arch during all closed grinding movements of mandible

    Freeway space
    1.   2-4 mm of free space in  vertical dimension  for construction of complete denture
    2.   This is the distance between the two arches in rest position
    3.   This space is variable in individual mandibular movements in speech

    Position of Upper anterior teeth
    1.   Are set labial to the residual ridge
    2.   They are 10mm labial to the middle of the incisive papilla
    3.   About 2-3 mm of teeth are shown when lips are apart and relaxed

    Lower anterior teeth
    1.   If there is little ridge resorption ,
    2.   teeth should be placed marginally in front of the ridge crest
    3.   In cases where there is lots of ridge resorption
    4.   teeth should be placed to the buccal sulcus

    Upper posterior teeth set up
    1.   slightly buccal to  the residual ridge
    2.   and parallel to the ala-tragus line

    Lower posterior teeth set up
    Teeth should be set directly over the ridge

    According to individual needs  of patient
    Without loss of functional concepts

    Types of impressions

    1.   Mucocompressive and
    2.   Mucostatic

    Mucocompressive impression is,
    1.   an impression under load  
    2.   so that the mucosa is reduced  in volume  equally and evenly condensed

    Mucostatic impression is,
    1.   Made without load application 
    2.   so that mucosa is neither displaced nor compressed 

    for insertion of complete denture incorrect occlusal balance is checked by ,
    1.   using articulating paper
    2.   and modified by selective grinding

    If  there is muscle balance problem ,
    grinding  of denture periphery may be required
    overextention  should be  corrected
    speech checked
    and patient allowed to comment on denture 

    Common denture problems
    1.   Inadequate support
    2.   Pain on pressure on supporting areas
    3.   Discomfort under denture
    4.   Burning sensation in denture bearing areas
    5.   With no redness or ulceration

    Inadequate retention  Loose denture
    1.   At rest and in function
    2.   Denture can be removed without any resistance
    3.   Denture is removed from mouth after firmly seated in mouth
    4.   is treated by improving peripheral seal by self cure acrylic
    5.   relining the denture may be required

    Muscle balance problem
    1.   dentures becomes loose during function and drops
    2.   denture feel too large
    3.   cheek biting
    4.   on tongue protrusion lower denture comes out
    5.    this is treated by careful trimming of denture area encroaching on muscles .

    Occlusal balance problem
    1.   patient wears denture well but find difficult to eat with it
    2.   there may be pain on pressure  or
    3.   denture moves when teeth grind together
    4.    problem can be treated by slective grinding or
    5.    laboratory remounting  or
    6.    resetting of teeth

    Appearance problem
    1.   shade of tooth wrong
    2.   shape of teeth wrong
    3.   too much or too little tooth shows
    4.   lips look odd
    5.   face looks asymmetrical , patient unhappy
    6.   problem is treated by resetting of teeth
    7.   is due to incorrect recording vertical or horizontal components of occlusion

    Speech problems
    1.   problem with F and V sounds or hissing S sounds
    2.   may be due to tooth position
    3.   or vertical dimension of occlusion
    4.   notoriously difficult problem to solve

    1.   Retching is a  protective reflex
    2.   Examination and impression taking is difficult
    3.   There may be psychiatric elements to retching
    4.   is treated by progressive adaptation to denture
    5.   construction of base plates first
    6.   hypnotherapy or desensitization therapy

    Acrylic allergy

    For proven acrylic allergy an alternative material may be considered

    Acrylic alternatives are
    1.   Vulcanite
    2.   Nylon
    3.   Polycarbonate  are useful alternative materials
    4.   porcelain  teeth are alternative to acrylic teeth

    Partial Dentures Aim
    1.   Partial denture should not damage the adjacent teeth
    2.   Or restoration
    3.   Partial denture is designed according to the periodontal health
    4.   Should restore function and aesthetic

    Problems arising as a result of non replacement of missing teeth ,
    1.   Dirffting and tilting of adjacent teeth
    2.   Overeryption of opposing teeth
    3.   Decreased masticatory function
    4.   craniomandibular disorders
    5.   overloadoing of remaining teeth  or mucosa
    6.   tooth wear
    7.   poor oral hygiene
    8.   speech problems
    9.   aesthetic problems

    Negative effects of partial dentures
    1.   increased plaque accumulation
    2.   dental caries
    3.   gingivitis
    4.   periodontitis
    5.   gingival stripping
    6.   overloading of abutment teeth

    These problems can be solved by,
    1.   careful partial denture  design
    2.   patient selection
    3.   motivation
    4.   oral hygiene instructions
    5.   regular checkups
    6.   and achieved before partial denture construction

    Partial denture Design

    Systematic approach to partial denture design construction must be followed for each case according to the Kennedy classification

    Kennedy classification of edentulous space

    Class I = bilateral free end saddle
    Class II = unilateral free end saddle
    Class III = unilateral bounded saddle
    Class IV = anterior across the mid line

    Saddle classification,(Craddock's classification)
    1.   Saddle is part of alveolus from which teeth are missing
    2.   Mucosa borne – e.g.  bilateral free end saddle
    3.   Tooth borne – e.g. small bounded saddle
    4.   Tooth and mucosa borne

    Types of connectors in maxilla
    1.  Anterior palatal bar – used for anterior saddle or for indirect retention in a bilateral free end saddle
    2.   Mid palatal bar – connect 2 posterior bounded saddle
    3.  Posterior palatal bar - Posterior border on the vibrating line used for free end saddles
    4.   Palatal horse shoe  connector – for anterior saddle
    5.   Full coverage palatal plate is used when very few natural teeth are present.

    Types of connectors in mandible
    1.   Lingual bar – needs to be 4 mm deep and 3 mm thick , 1.5 mm away from the gingival margin  and 1.5 mm above the floor of mouth
    2.   Lingual plate  used when insufficient room for lingual bar
    3.   Lingual bar and continuous clasp - provides indirect retention than lingual bar but had many sharp edges
    4.   buccal bar –very few indications
    5.   sub lingual bar – lies low in floor of mouth

    Metals sued for clasp are ,
    1.   stainless steel
    2.   cobalt chromium
    3.   wrought gold

    For different undercuts depths different metals are used
    1.   For 0.75 mm undercut - stainless steel is used
    2.   For 0.25 mm undercut - cobalt chromium is used
    3.   For 0.5 mm undercut - wrought gold is used.

    Partial denture clasps can be
    1.   Occlusally approaching clasp
    2.   Gingivally approaching clasp
    3.   I bar clasp

     Rests provide tooth support common types include,
    1.   Occlusal rests
    2.   Cingulum rest

    Occlusal rests – placed mesially or distallty on
    1.   occlusal surface of molars or premolars .
    2.   may require tooth prepration ,
    3.   must not interfere occlusion

    Cingulum rests are placed on the
    1.   cingulum of incisors and canine
    2.   may require tooth prepration


    1.  During fabrication of lower denture it was slightly extended so what muscle does it touch.
    2.   Why is it that you cure slow overnight than rapid cure
    3.   Which nerve supplies the posterior third of the tongue?

    What is an immediate denture?
    An immediate denture is a complete denture or partial denture inserted on the same day, immediately following the removal of natural teeth.

    What are the advantages of an immediate denture?

    1.  There are several advantages of an immediate denture.
    2.  The most important factor is that the patient  will never need to appear in public without teeth.
    3.  It is also easier to duplicate the shape, color and arrangement of  natural teeth while some are still present in mouth.
    4.   When an immediate denture is inserted at the time of extraction,
    5.   It will act as a Band-Aid to protect the tissues and reduce bleeding.
    6.  An immediate denture will allow establishing speech patterns early. You will not have to learn to speak without a denture in place and then later relearn to speak with a new denture.
    7.  An immediate denture will also allow to chew better than without any teeth and minimize facial distortion that may occur when teeth are removed.

    What are the disadvantages of an immediate denture?
    1.   The biggest disadvantage is the increased cost.
    2.   Another disadvantage is that you cannot always see how the denture will look before the teeth are extracted and the immediate denture is inserted.
    3. Also, initially, an immediate denture does not always fit as accurately as a conventional denture,
    4. Which is made after the tissues have healed for six to eight weeks following extractions, and without wearing a denture.

    Why does an immediate denture cost more?
    1.   An immediate denture is initially more expensive than a conventional denture because additional time is needed for construction.
    2.   A surgical stent (a guide for recontouring tissues after extraction) is often necessary and
    3.   more follow-up visits are needed for adjustments and re-fitting.

    A soft temporary reline material will be utilized for re-fitting denture when it becomes loose during the healing process.

    1.   After the soft tissues have healed and
    2.   shrinkage of the underlying bone has occurred
    3.   about six months following extractions

    The immediate denture must be finalized
    1.   by a permanent reline or new denture.
    2.   At this time, patient will be charged for either a reline or a new denture, depending on choice.
    3.   discuss with  the patient  the  pros and cons of a permanent reline versus making a new denture,

    A major advantage to making a new denture is,

     that the immediate denture can be a spare denture if the new denture breaks, is misplaced, or has to be repaired or relined in our laboratory.

    A major disadvantage to relined, denture is
    If the immediate denture is relined, it will usually need to be left overnight while it is permanently relined in the laboratory.

    Is an immediate denture for everyone?
    1.   Not everyone is a candidate for an immediate denture.
    2.   Some people may be advised against this treatment,
    3.   due to general health conditions, or
    4.   because of specific oral problems.

    How long does it take to complete?
    1.   Four to five visits may be necessary for the fabrication phase of an immediate denture,
    2.     Plus any preliminary surgery.
    3.   For patients requiring a complete immediate denture, the back teeth are often extracted six to eight weeks prior to the fabrication phase.
    4.   This allows the extraction sites to heal and a better-fitting immediate complete denture to be fabricated.

    The fabrication phase consists of,
    1.   impressions,
    2.   bite records,
    3.   tooth selection and
    4.   try-in of the back teeth.

    On the day of delivery,
    1.   patient  will be seen in oral surgery
    2.   for extraction of the appropriate teeth,
    3.   followed immediately by the insertion of the immediate denture.

    Dentures reline helps
    1.   an old denture fit better
    2.   As with age gums and bone underneath the denture changes
    3.   the bone in the mouth was meant to support natural teeth and
    4.   when these teeth are lost, the bone resorbs quickly
    5.   denture acrylic keeps its shape and form while the gums and bone change
    6.   so that older  denture can get loose and rub the underlying gums tissues  resulting in ulceration
    chairside dentures reline,
    1.   Grinds away some of the acrylic that contacts the gums.
    2.   This makes room for new acrylic without significantly changing the plate.
    3.   New acrylic is added to the old and
    4.   the new acrylic base is custom fitted to the shape of the gums and bone.

    The self cure acrylic used for relining
    is not as hard and durable as the processed acrylic used to make the  heat cure acrylic

    advantage of chairside procedure is,
    1.   its quick and
    2.   patients don't have to wait a day or two to get their plates back.

    Alginate Impression Materials

    1.   Container of powder should be shaken before use to get an even distribution of constituents.
    2.   Powder and water should be measured to manufactures instructions.
    3.   Water at room temperature should be used,
    • this gives a reasonable working time of ,a couple of minutes.
    • Faster or slower setting times can be achieved,by using warm or cold water respectively.
    • The material nearer the tissues, sets first .
    Retention is needed to the impression tray and is provided by
    perforations in the tray and/or adhesives.

    Once removed from the mouth the impression should be,
    1.   Rinsed with cold water to remove any saliva or blood.
    2.   It should then be covered in a damp gauze/napkin to prevent syneresis
    3.   (not placed in water which would cause imbibition-expansion).
    4.   The impression should be soaked in hypochlorite for 60 seconds and then cast as soon as possible.

    Properties of Alginates

    1.   On mixing the powder with water a sol is formed,
    2.   a chemical reaction takes place and
    3.   a gel is formed.

    The powder contains
    1. Alginate salt (e.g. sodium alginate)
    2. Calcium salt (e.g. calcium sulphate)
    3. Trisodium phosphate

    The setting reaction is as follows:
    On mixing the powder with the water



    The chemical reaction occurs too quickly
    often during mixing or loading of the impression tray.

    It can be slowed down by,
    1.   adding trisodium phosphate to the powder.
    2.   This reacts with the calcium sulphate
    3.   to produce calcium phosphate,
    4.   preventing the calcium sulphate reacting with the sodium alginate to form a gel.

    This second reaction occurs in preference to the first reaction
    1.   until the trisodium phosphate is used up,
    2.   then the alginate will set as a gel.
    There is a well-defined working time during which there is no viscosity change.

    PROPERTIES of alginate
    • Good surface detail
    • Reaction is faster at higher temperatures
    • Elastic enough to be drawn over the undercuts, but tears over the deep undercuts
    • Not dimensionally stable on storing due to evaporation
    • Non toxic and non irritant
    • Setting time can depend on technique
    • Alginate powder is unstable on storage in presence of moisture or in warm temperatures
    1. Non toxic and non irritant
    2. Good surface detail
    3. Ease of use and mix
    4. Cheap and good shelf life
    5. Setting time can be controlled with temperature of water used

    1. Poor dimensional stability
    2. Incompatibility with some dental stones
    3. Setting time very dependent on operator handling
    4. Messy to work with

    Denture maintenance

    Ill-fitting denture results in
    1.   Resorption of ridges
    2.   Candida infection
    3.   denture irritation hyperplasia
    4.   Inflammatory papillary hyperplasia of palate

    Rebasing is,
    1.   Replacement of all of denture base
    2.   When improvement in the fitting surface is required
    3.   Heat cure acrylic is the material  of choices

    Relining is,
    Replacement of fitting surface with a self cure acrylic

    Laboratory dentures relining is a similar procedure.
    1. Instead of using self cure acrylic,
    2.The old denture is used to take a precise impression of the underlying tissues with very accurate impression material.

    The old denture is sent to a dentures lab and new acrylic
    1.   is processed to the old denture in the same manner that the original denture was manufactured.
    2.   The result is a very nice well fitting old denture.

    A dentures relining
    1.   can help make wearing dentures much more comfortable ,
    2.   but they should always be replaced every five years
    3.   to adjust to the natural changes of face and
    4.   the changes in the bone within  mouth.

    Immediate denture definition,

    denture provided to the patient soon after extraction of a tooth

    Q: advantages of  Immediate denture for dentist,

    1.   smooth wound healing ,
    2.   conservation of apace,
    3.   provision of primary basis, 

    Advantages of immediate denture for patient

    1.   immediate replacement of  extracted tooth
    2.   no aesthetic loss,

    Disadvantages of immediate denture  

    1.   denture becomes loose with time
    2.   due to bone resorption and
    3.   tissue regression, 
    4.   cost of new denture due to repeat denture

     Copy denture is

    1.   When old denture is used to make new denture.
    2.   definition: patient’s  old denture is used as a model to make new denture.

    Indications of copy denture;
    1.   when patient is satisfied with the old denture , or
    2.   not willing to pass through any of the steps of denture making
    3.   e.g. impression taking  or trial 

    Contraindications of copy denture
    1.   When denture is loose or
    2.   has a major defect, or
    3.   there is change in the oral structures
    4.   e.g extraction of a tooth or boone resorption

    Disadvantages of copy denture
    Any fault present in the old denture is likely to be repeated.
    Maxillary tuberosity and tooth fracture management?
    Allow the fracture to heal by providing a supportive appliance e.g a denture or splint
    Centric Occlusion

    1.   the maximal intercuspation of the teeth.
    2.   The relationship of the mandible to the maxilla
    3.   when the teeth are in maximum occlusal contact,
    4.   irrespective of the position or alignment of the condyle-disk assemblies.
    5.   The occlusion of opposing teeth when the mandible is in centric relation.

    Centric Relation = retruded contact position

    1.   The position of the mandible
    2.   when the condyles are in an orthopedically stable position.

    This occurs when the condyles are in their most superoanterior position,
    1.   Resting on the posterior slopes of the articular eminences with the disks properly interposed.
    2.   The maxillomandibular relationship
    3. in which the condyles articulate with the thinnest avascular portion of their respective disks
    4.  With the complex in the anterior-superior position against the slopes of the articular eminences.
    5.   This position is independent of tooth contact.
    6.   syn. retruded contact position

    Compensating Curve

    1.   The anteroposterior curvature (in the median plane) and the mediolateral curvature (in the frontal plane)
    2.   in the alignment of the occluding surfaces and incisal edges of artificial teeth
    3.   that are used to develop balanced occlusion.

    Cross-Bite= reverse articulation

    1.   When the maxillary teeth occlude with buccal cusps contact the central fossa of the mandibular teeth.
    2.   An occlusal relationship in which the mandibular teeth are located facial to the opposing maxillary teeth;
    3.   the maxillary buccal cusps are positioned in the central fossae of the mandibular teeth.
    syn. reverse articulation

    Curve of Monson
    archaic sees Compensating Curve

    Functional Occlusion
    is the contacts of the maxillary and mandibular teeth during mastication and deglutition.

    Most common Denture problems

    Most common denture problem is,
    1.   Pain on insertion  or
    2.   loose denture

    Can be due to ,
    1.   Denture errors or
    2.   Patient factors

    Patient fctors are ,
    1.   patient should be warned in advance the limitations of a denture
    2.   excessive salivation
    3.   speech problems pain
    4.   bruxism
    5.   other paranormal habits , like clenchinh of teeth

    Causes of pain,
    1.   Rough fitting surface
    2.   Errors in occlusion
    3.   bruxism
    4.   Retained root
    5.   Sharp alveolar ridge
    6.   Premature contact
    7.   Excessive bone resorption – mental foramen pressure or exposure in localised area of pain
    8.   Leverage – due to unstable denture
    9.   Clasp arm too high

    Complain of loose denture is more in,
    Lower denture

    Altered Cast Technique

    1.   In Free end saddles dentures ,
    2.   There is displacement of denture  under occlusal pressure
    3.   There is anteroposterior rocking around the abutment tooth, which acts as a pivot.
    4.   This is as a result of the displaceability of the mucosa.

    The altered cast technique is employed
    1.   to try and prevent this anteroposterior rocking around the abutment tooth,  
    2.   by taking an impression of the mucosa under controlled pressure.
    3.   The metal framework is constructed on a cast produced by a mucostatic impression material, usually alginate.
    4.  Baseplates are then constructed in self-cured acrylics on the framework in the saddle areas, these are close fitting.
    5.  Impression paste or a medium viscosity silicone paste is then applied to the fitting surface of the self-cured acrylic.
    6.   The denture is then inserted in place, held in place by the framework only,
    7.    no finger pressure is applied as this would lead to over displacement of the mucosa.
    8.   Border moulding is then carried out as the is impression material is setting.

    1.  In the laboratory, the free end saddle areas on the master cast are sectioned off.
    2.  The denture is then positioned on the model and the new saddle areas are poured.
    3.  The resulting model represents the free end saddle areas under conditions, which mimic functional load.
    4.  Denture construction then continues as normal.
    5.  The distribution of loading of the free end saddles is improved and denture is more stable.

    How long do I leave the impression in the mouth before it's fully set?
    1.   Setting time in the mouth is based on use of room temperature water.
    2.   All materials will gel in 5 minutes except one.
    3.   Lavender Acculoid requires 7 minutes to gel.

    How do I disinfect my hydrocolloid impressions?
    Hydrocolloid impressions may be disinfected by immersion in one of the following:
    1.   Sodium Hypochlorite,
    2.   Iodophor,
    3.   Acid Gluteraldehyde.

    Sterilization Pouches

    Sterilization Pouches offer not only the highest quality dental pouch, but also features the patented Internal-Processing-Indicator. Available in 12 sizes

    Fixed and Removable Prostheses

    Any fixed or removable prosthesis which has been in the patient's mouth ,
    1.   must be rinsed under running water to remove excess blood and saliva.
    2.   Do not splash water excessively;
    3.   droplet spatter can carry microorganisms.

    For Cleaning Dentures Place the prosthesis in,
    1.   an ultrasonic cleaner
    2.   with Midwest Stain and Tartar Remover
    3.   for the manufacturer’s recommended time.
    4.   This is the pre-cleaning step of the disinfection procedure.

    Prior to adjustment or transport to the laboratory, disinfect the prosthesis as follows:
    1.   Rinse with water and spray with a complex phenol disinfectant.
    2.   Place in a plastic bag for 10 minutes, and
    3.   Rinse with water.
    4.   Wrap prosthesis in plastic (or place in a plastic bag) and send to the laboratory.
    5.   Do not add disinfectant to the bag.

    Cleaning Dentures

    1.   Use Midwest’s Stain and Tartar Remover and follow manufacturer's directions for proper dilution.
    2.  With gloves and safety glasses on, pour Stain and Tartar Remover solution directly into bag containing dentures.
    3.   Close bag and place in a glass cylinder.
    4.    Fill cylinder with water.
    5.   Place cylinder in ultrasonic cleaner and vibrate for manufacturer’s recommended time.
    6.   Wearing clean gloves,
    7.   remove dentures from bag and thoroughly rinse with water.
    8.   Place dentures in denture cup containing mouthwash.
    9.   Remove and discard gloves and wash hands.
    10. Return denture cup to the student or faculty member.

    Disinfecting Impressions; Alginate or polyether:

    1.   Rinse with water and

    2.   spray with a complex phenol disinfectant.

    3.   Place the impression in a plastic bag for 10 minutes,

    4.   rinse with water, and pour.

    5.   Pour alginate impressions immediately;

    6.   pour polyether impressions immediately or within 24 hours.

    Polysulfide, silicone, and polyvinylsiloxane:
    1.   Rinse with water and
    2.   immerse in a complex phenol disinfectant for 10 minutes.
    3.   Remove and rinse again with water.
    Pour polysulfide and silicone impressions,within 15-60 minutes;
    Pour polyvinylsiloxane impressions , within 15 minutes to seven days.

    Cleaning/Disinfecting Prosthodontic Items

    1.   Items contaminated only by handling or
    2.   that have minimal contact with oral fluids
    3.   do not require sterilization for routine reuse,
    4.   but should be cleaned and disinfected with an EPA-registered disinfectant.
    Such items include,
    1.   torches,
    2.   face bows (not including the facebow fork),
    3.   articulators,
    4.   rulers,
    5.   mixing spatulas,
    6.   knives,
    7.   rubber bowls,
    8.   shade guides, and
    9.   mold guides.

    Any items such as impression trays and facebow forks that are placed in the mouth,
     Should be heat-sterilized.

    Contaminated Stone Casts

    Contaminated stone casts transferred to or from a laboratory area or a clinic
    1.   should be sprayed with a complex phenol disinfectant and
    2.   allowed to set for 10 minutes before rinsing thoroughly with water.
    3.   A protective mask must be worn when using a model trimmer.

    Other Work-Related Items

    1.   All other work-related items (articulators, case pans, etc.)
    2.   which are transferred from a clinic to a laboratory area or vice versa
    3.   must be disinfected.
    4.  Moving parts of the articulator should not be disinfected since this may impair function.

    The following items should be cleaned and heat-sterilized or chemically disinfected as indicated:

    1.   recommended on primary molars
    2.   Grossly carious molars
    3.   tooth has received a pulpotomy
    4.   provide more durable and reliable restoration.  


    Sticky foods like caramel, gum, taffy

    Hard candy

    Chewing on ice

    Popcorn kernels or "old maids

    The crown of the tooth is protected
    1.   Where the crown meet the gum tissue is an area where bacteria can live and cause decay. 
    2.   It is important that parents supervise the cleaning of this area. 
    3.   Make sure  child brushes not only his teeth but where their teeth meet the gum tissue. 
    4.   It is also important to floss, especially in this area, once a day. 
    5.   Brush teeth and not flossing is leaving 40% our mouth loaded with acid protecting bacteria!     
    6.   The crowned tooth will usually fall out normally when the permanent tooth comes in.


    1.   Save all the parts of broken denture, bridge or partial denture
    2.   Repair or replace as soon as possible
    3.   Temporary bridges, plates and dentures until the permanent one is repaired or replaced

    • If a wire is causing an irritation, cover the end of the wire with some bees wax or a piece of gauze
    • If a wire becomes embedded in the gum or cheek DO NOT remove  it, go to the dentist immediately  

    1.   Try to snap it back in
    2.   Purchase a small tube of denture adhesive paste put a small amount in the crown and place it back on your tooth
    3.   Try Dent Temp or Tempenol as a temporary adhesive
    4.   Do NOT use ordinary household glue
    5.   Call the dentist as soon as possible to recement it properly  

    Q: Instructions for Denture?

    1.   For dentures, a written leaflet is given which is discussed with patient.

    2.  Major highlight of this is emphasis on denture hygiene- twice daily routine of brushing, soaking and then brushing again should be adopted.

    3.  Brushing is with small multitufed toothbrush to help gain access to awkward corners.

    4.   after brushing, denture should be soaked in a specialist cleaner to help to remove stubborn stains, calculus and plaque.

    5.   If patient has to leave the new dentures out because of pain or soreness, request that the dentures be worn 24 hours before the review appointment, 

    6.   in order that the cause of the discomfort may be more readily detected.

    An Articulator
    1.   An articulator assists in the fabrication of removable appliances (dentures),
    2.   is a mechanical device used to casts of the maxillary and mandibular teeth are fixed and
    3.   reproduces recorded positions of the mandible in relation to the maxilla.
    4. fixed prosthodontic restorations (crowns, bridges, inlays and onlays)and orthodontic appliances.

    Plane line articulator

    1.   The simplest type of articulator consisting of a simple hinge joint.
    2.   No lateral or sliding movements are possible with a plane line articulator.
    3.  An articulator that allows that reproduces movement of the mandible only in a sagittal plane.