৪৮তম বিশেষ বিসিএস [স্বাস্থ্য] ⎯ ডেন্টাল অংশ [Archived]

Resin bonded FPD:

Based on technique/type of retention, Resin bonded FPD classified as follows: 

A. Mechanical- Rochette bridge 

B.Micromechanical -  Maryland Bridges 

C.Macromechanical- a)Virginia bridge b) Cast mesh fixed partial denture

D. Chemical -[ most commonly used method for bonding resin bonded FPD]
  Example-Adhesive bridge.
Materials used- Super bond,Rocatec system, Modified bis-GMA cement.

Ref: Rangaranjan 2nd edition


Cantilever bridge-- type of bridge where support can be obtained only one side of edentulous space( that means use only one abutment instead of using 2 abutment in Conventional FPD) 


Ref: deepak nallaswamy 2nd edition

Function of different component parts of RPD:

1. Minor connector- act as a connecting link.Connects other components with the major connector. 

2.Major connector- Largest and Most important component & forms basic framework of RPD. Connect all parts on one side arch to those on opposite part.

3. Rest- Transmit the occlusal forces along the long axis of the abutment tooth

4. Direct retainer-  Most critical component. Prevents the displacement of the denture.

5.Indirect retainer- Retains the denture in place. Assists direct retainer by level action on the opposite side of the fulcrum line.

6.Denture base- Distributes the force acting on denture over the entire residual ridge. Holds the tooth replacements in position. 

7. Artificial tooth replacement - reproduces the contour & function of the missing teeth..

First 5 are components of cast in metal. Others 2 are fabricated using other materials.  




Ref: Deepak Nallaswamy 

Kennedy's classification :
Most popular to classify edentulous arch-

Posterior area
A. Class I
B.ClassII 

Anterior area

C.Class III
D.Class IV


Class I arches are most common.
Class  IV arches are least common.

Ref- Deepak Nallaswamy

To determine the potency of an abutment, periodontal ligament area is measured by Ante' s Law.

Ante's Law: The sum of the pericemental areas of abutment teeth should be equal to or surpass that of the teeth begin replaced. 

That means, The total pericemental surface area of the abutments should be equal to or greater than that of the missing teeth  

If Pericemental area is not sufficient according to Ante's Law, an additional tooth should be used as a secondary abutment. 


Ref: Deepak

6 common types of mandibular major connector RPFmD are:
1. Lingual bar-most commonly used  
2.Lingual plate
3.Kennedy bar/double lingual bar.
5.Sublingual bar
6.Mandibular cingulum bar/continuous bar
7.Labial bar.

Ref: Deepak

Rest: Rigid  part of RPD that contacts the  remaining teeth to dissipate vertical or horizontal forces.
Function -a) Primarily transfers  forces acting on the  denture along the long axis of abutment teeth.
b) Act as a vertical stop to prevent injury to soft tissue under partial denture.

Rest seat: A shallow and saucer/spoon shaped prepared surface of the tooth into which the rest fits. It is made on enamel part of tooth Only. 

Generation consideration : 
 1. Should be placed on the proximal surfaces of all teeth adjacent to the edentulous space.
2.should be aligned to the crest of the edentulous ridge.
3. Rest should move slightly within the rest seat( ball& socket joint)



ref: Deepak

Component parts of a clasp in RPD:

1. Retentive terminal- Only flexible part of the cusp and Only  component that crosses the height of contour during insertion& removal of the denture.
2. Retentive clasp arm.
3.Reciprocal arm.
4. Occlusal  rest
5. Shoulder.
6.Body.
7. minor connector.

Ref: Deepak Nallaswamy

Designing a RPD includes determining the path of insertion of the denture,location,position & type of components to be used in Prosthesis. 

RPD designed on an  instrument is called surveyor and the procedure is called surveying.

So,it is the first step in design of a RPD


Ref: Deepak Nallaswamy 

Type of Lever: 3types
1. Ist order levers
2.2nd order levers
3.3rd order levers

Ist order levers is seen in patients with distal extension partial denture..More efficient &easily controlled. 

2.2nd order levers can be achieved by converting 1st order lever using indirect retainer which is more beneficial to Prosthesis (generally seen)

3.3rd order levers- Dose not occur in partial denture.

Ref: Deepak

Bar clasp:

1.Arises below the height of contour of the  abutment teeth.
2.Has a flexible minor connector 
3.easier to seat
4.Less bracing effect due to 3-point contact. 
5.More aesthetic 
6.No calcification 

Disadvantage : 1.Difficult to remove & repair
2. More complex design.
3. Increases food debris accumulation 


Ref: Deepak

Indication of FPD:
1.Short span edentulous space 
2.Presence of sound teeth with sufficient support adjacent to the edentulous space. 
3.Cases with ridge resorption. 
4.Patient preference 
5.Mentally compromised & physically handicapped patient.

Contraindication of FPD:

1. Long span edentulous space 
2.Periodontally compromised abutments. 
3.Very young patients 
4.Bilateral edentulous space 
5.Very old patients 
6.Medically compromised patients (leukemia, HTN)
7.Mentally sensitive patient. 
8.Congenitally malformed teeth.

Ref: Deepak

Pier Abutment :

A single tooth (that is going to be used as abutment in FPD) is surrounded by an edentulous space on either side. 

Ref: Deepak

Classification of pontics:

Based on the amount of mucosal contact -

A.With mucosal contact 
 1 Saddle pontic
2.Ridge lap pontic
3. Modified ridge lap pontic
4.Ovate pontic

B.Without mucosal contact
1.Bullet pontic
2.Hygienic or sanitary pontic

*Trupontic is a prefabricated pontic

Ref: Deepak.

The factor influenceing the choice of an Abutment :

1.Location,position & condition of tooth
2.Root configuration 
3.Crown root ratio
4.Root support 
5.periodontal Ligament area.
6.Assessment of pulpal health.

crown root ratio : Length of crown & root should always be less than one. Here,Length of Crown indicates the length of tooth structure above the crest of the alveolar bone.
Ideal crown : root is - 2 : 3
Upto 1:1 is acceptable. 
More than one is unacceptable. 

Ref: deepak.

The role of an abutment is Very crucial because, it accepts the load acting on a FPD and has to withstand both the forces - a)Acting  on it b) Acting on the pontic.

Hence, Abutment selection is the most important factor in the design of a FPD.


Ref: Deepak.

Contraindication of All ceramic crown preparation : 
1.High caries index
2. Insufficient coronal tooth structure for support. 3.Bruxism.
4.Unfavorable distribution of occlusal load
5.When metal ceramic crown is more appropriate for Greater strength.

Ref: Deepak

Type of maxillary defects :

Broadly classified 2 categories -

A.Congenital
1.Cleft lip
2.Cleft palate.

B.Acquired
1 Total maxillectomy
2.Partial maxillectomy.


*Most common congenital maxillary defects include cleft lip& palate. others defect are
a) Sub mucous cleft palate.
b)Pierre Robin syndrome
c) Hemifacial microsomia

Ref : Deepak

An ideal abutment shoulder have-

1.Ideal crown root ratio.
2.Adequate thickness of enamel & dentine
3.Adequate bone support
4.Absence of periodontal disease 
5. Proper gingival contour

Ref: Deepak 

Basic principle of tooth preparation :

1.Preservation of tooth structure. 
2. Retention & resistance 
3.structural durability
5. Marginal integrity 


Taper is important to balance between three retention & resistance form.

Zero(0°) degree taper is most retentive but impossible to obtain.
 Optimum retention 4°-10° converge is sufficient to obtain rentiontion.


Ref: Deepak.

Crown- Extracoronal restoration 
Inlay & Onlay -  Both are intracoronal restoration 

Ref: Deepak

Ref. Bhalajhi 9th edition,  page 04.

convex facial profile is associated with 
1) prognathic maxila
2) Retrognathic mandible 
3) class 2, div 1

The space is 0.9 mm on each side in maxilla and total 1.8 mm in upper arch and 1.7 mm on either  side in mandible total 3.4 mm in lower arch

it is a temporary phase during the process of normal development developing upper permanent Canon causes medial displacement of roots of permanent Incisor, distal divergence  of crown of these incisors.this usually correct itself.
Ref Bhalajhi Ed 7th page 70

Thumb sucking habit may causes anterior open bite and spacing on upper anterior  segment due to flaring of upper anterior teeth.
Ref. Bhalajhi ed 7th, pg- 142

Ref: prof. Emadul page -25
strap like lip:
1.lower lip line in low 
2.Mandibular alveolar process grow at a retruded position 
3.lower incisors  may also be retrocliened 
4.class 2 division 1 Incisor relationship

ক) curve spee should be flat.
খ) absence of rotation 
গ) tight contact should be present

ক)sagittal plane
গ,ঘ) Vertical plane 
Ref. Pfof. Emadul,  pg -33

Angle class 2 malocclusion 
lower arch occlude at least half a cup distal than normal in relation to the upper arch judged by the first molar relation ship. this arch relationship  is called disto-culation or post normal occlusion 
Ref: prof Emadul,pg -34

Angle considered naloculation only in the anterior  poster plan 
Psudo class 3 cannot be classified 
individual teeth male position is  not included 
Ref.Bhalaji edition 7th page 105 

Features  of class 2 division 2 Malocclusion
Retroclanation of Central incisors
molars in disto occlusion 
backward path of closure 
deep over bite
deep mentolabial sulcus
※ Ref. professor emadul page 167 

causes of pseudo class 3 malocclusion 
1. Presence  of occultural prematurity may deflect the mandible  forward 
2.In case of premature loss of deciduous posteriors, the child tends to move the mandible  forward to establish contact in the anterior  Region 
3.a child with enlarged adenoids tends to move the mandible  forward in an attempt to prevent the tongue from contracting the adenoids 
※ Ref  Bhalajhi edition 7 page 103-104 

in pressure area, cells are 
1) osteoclast 2) fibroblast 
※ ref Bhalahji  7th edition page- 242 

theories of tooth movement 
1) pressure tension theory 
2) blood flow theory 
3) bone bending theory 
4) piezo electric theory
※ ref  Bhalahji 7th edition page -288

Corrections  of developing cross bite - interceptive orthodontic  procedure

arch contraction- corrective orthodontics
※ Ref  Bhalajhi edition 7th page_299 

Active  components are
Labial bow
springs
Expansion  screw
elastics
Arch wires

The following appliance can be group under the functional appliance 
bite plan
Activator
frankl appliance
twin block appliance
Jasper jumper
bass appliance
Ref. Balaji 7th edition page394