1
Q
Arcon Articulators
vs
Non-Arcon Articulators
A
Arcon Articulators: mimic TMJ more closely by having the condylar path elements (condyles) = lower member and the articular disc components on upper member. This setup resembles the anatomical arrangement of the human TMJ, thus, simulating > jaw movements.
Non-Arcon Articulators: The setup is reversed, with the condylar path elements placed on the upper member and the articular disc elements on the lower member. This type does not mimic the anatomical features of the TMJ as closely as arcon models and is typically simpler in design.
2
Q
7x factors to consider when deciding which tx option btw RPD, FDP, RBB, IMPLANTS
A
- Span Length
- Span Configuration
- Abutment Alignment
- Abutment Condition
- Occlusion
- Periodontal Condition
- Ridge Form
3
Q
- Span Length criteria for
RPD
FDP
RBB
implant
A
- Span Length
(RPD): Can span > than 2 teeth posteriorly and > 4 anteriorly.
(FDP): Suitable for spans of 2 or fewer posterior teeth and up to 4 incisors.
RBB Typically used for single teeth, occasionally 2 incisors.
Implant-Supported Fixed Partial Denture: Ideal for single tooth and spans up to 6 units.
4
Q
- Span Configuration criteria for
RPD
FDP
RBB
implant
A
- Span Configuration
RPD: no distal abutment and multiple edentulous spaces.
Conventional FPD: Uses distal abutments; short cantilever possible.
Resin-Bonded: Mesial and distal abutments to the pontic.
Implant-Supported: No distal abutment req, supports from implant to implant.
5
Q
- Abutment Alignment criteria for
RPD
FDP
RBB
implant
A
- Abutment Alignment
RPD: Tolerates tipped abutments and divergent alignment.
Conventional FPD: Accepts <25-degree inclinations with modifications.
Resin-Bonded: Req <15-degree angulation mesiodistally, same inclination faciolingually.
Implant-Supported: Needs close alignment between implant and abutment.
6
Q
- Abutment Condition criteria for
RPD
FDP
RBB
implant
A
- Abutment Condition
RPD: Can use short clinical crowns and insufficient abutments.
Conventional FPD: Suitable if abutments need crowns or have significant dental structure.
Resin-Bonded: Prefers defect-free abutments.
Implant-Supported: abutments not req.
7
Q
- Occlusion criteria for
RPD
FDP
RBB
implant
A
- Occlusion
RPD: Adaptable to irregularities in a healthy opposing dentition.
FPD: Supports favorable loading conditions.
Resin-Bonded: Cannot be used for incisor replacement if deep overbite
Implant-Supported: Requires occlusal forces to be as vertical as possible.
8
Q
- alv bone Condition criteria for
RPD
FDP
RBB
implant
A
- Periodontal/alv bone Condition
RPD: Can use secondary abutments when primary are weakened.
Conventional FPD: Requires good alveolar bone support and no mobility.
Resin-Bonded: Needs stable periodontal support without mobility.
Implant: Demands dense bone for placement.
9
Q
- Ridge Form criteria for
RPD
FDP
RBB
implant
A
- Ridge Form
RPD: Suitable for cases with significant gross tissue loss.
FPD: Works well with moderate resorption.
Resin-Bonded: Requires moderate to no resorption.
Implant-Supported: Requires minimal soft tissue defects.
10
Q
ABUTMENT’S LOAD BEARING EVALUATION
1see … ratio
2 …shape
3 what bears stress?
A
1 Crown to root ratio 2:3 or minimum 1:1
2Root configuration Preferably broad buccal-lingually; widely separated roots >conical
better periodontal support
3 PDL area > ; can bear more stress
11
Q
ante law…..
A
Total root surface-all teeth supporting FPD should equal/exceed total root surface area of teeth being replaced.
BUT NOT a strict rule.
12
Q
pier abutment when there is ….
A
An edentulous space can occur on both sides of tooth, creating a lone, freestanding pier abutment
13
Q
solution to pier abutment acting in middle as fulcrum to unseat retainers on other abutments?
A
Nonrigid connector: a type of connector that allows for some movement between the parts of a dental bridge to distribute stress more effectively.
T-shaped key: This is attached to the pontic on the mesial side.
Dovetail keyway: Located within a retainer on the distal side. The T-shaped key fits into this dovetail keyway to join the components together.
14
Q
repair versus replacement factors to consider 5x
A
1 %S -Prognosis: refers to the likely of success or durability of the prosthesis
2 Medical limitation:
3 Time limitation:
4 Economic limitation
5 EXTent and complexity of damage affect whether it is feasible to repair it.
15
Q
Pain in post-RCT , post and core +crown done- suspect root fracture// pain in bridge - connector problem - why pain?
A
pain is attributed to extra force being transmitted to the abutment teeth, leading to discomfort from overloading the periodontal ligament (PDL).
16
Q
Mechanical Failure of Fractured
porcelain Causes: 8x
A
1 PREP-overprep=Excessive porcelain thickness without adequate metal support
2 PREP-Insufficient reduction- insufficient interoccl space
3 LAB-Improper laboratory procedures; Microcracks within ceramic
4 Habit=Excessive occlusal parafunction
5 OCCL=Lack of occlusal adjustment causing stress zones on ceramic
6 Trauma
7 material=Incompatible Coefficient of Thermal Expansion (COTE) between metal framework and ceramic
8 Fatigue failure due to environmental factors like masticatory forces, which can cause crack initiation, propagation, and eventual fracture
17
Q
general Management (Mx) of porcelain #
fractured but the multi-unit prosthesis is otherwise satisfactory, ….to avoid…
If there’s little or no functional loading on the fracture site, fractured porcelain can be bonded using a porcelain repair system with…
A
If porcelain is fractured but the multi-unit prosthesis is otherwise satisfactory, repair rather than remake might be justified to avoid additional discomfort, time, and expense for the patient.
silane coupling agents (e.g., 4-META) to promote bonding with composite resin (CR). Additional mechanical undercuts in the metal framework to improve CR retention.
18
Q
steps in repairing # porcelain
A
1 LA and RDI.
2 Porcelain/metal surface -slightly abrade with high speed diamond bur/micro abrasion.
3 Hydrofluoric acid etchant on crown; thoroughly rinse and dry surface .Porcelain will have a frosted appearance.
4 Apply Silane on the crown and allow to evaporate for one minute. After one minute, air dry.
5 if exposed tooth etch and bonding on tooth- Dry-thin 10 sec with oil free/moisture free air. Prep should appear shiny. Light cure for 10 sec. (20 sec. for lights with output<600mW/cm2 ).
6. Restore with composite of choice+ final cure.
19
Q
Characteristics of Mutual Protection occlusal scheme
it is Known as…
In centric relation only …tooth contact
In protrusion…
In lateral excursions,
Aims to
A
canine protected occlusion.
In centric relation, only posterior teeth contact, directing forces along their long axes.
In protrusion, only incisors contact.
In lateral excursions, only canines contact.
Aims to eliminate frictional wear.
Preferred for ease of fabrication and patient tolerance.
20
Q
Rationale for Mutual Protection (Class 3 Lever System):
A
The mandible functions as a Class 3 lever:
Joint serves as the fulcrum.
Muscles provide the applied force or force vector.
Teeth or bolus act as the load.
Anterior Teeth: Long, single roots=>Withstand lateral loads; furtherest from fulcrum,reducing lateral forces
Posterior teeth: Multi-rooted=Withstand vertical loads
21
Q
For optimum stability, comfort, and function, the anterior teeth must be:
A
1In harmony with the neutral zone
2 In harmony with the lips
3 In harmony with phonetics
4 In harmony with centric relation
5 In harmony with the envelope of function
results in tooth position and contours that are in harmony with functional anatomy that also produces
the most natural esthetics
22
Q
partial grp fx allows for
A
Allows some posterior teeth to share the load during lateral excursions, while others contact only in centric relation.
Decisions are made on a tooth-by-tooth basis:
eg If a tooth is weak laterally, it should contact in centric relation only.
23
Q
Group Function an occlusal scheme where post…share the load during …
A
Group function is an occlusal scheme where post teeth on one side of the dental arch work together to share the load during lateral movements. This helps distribute the forces exerted during chewing more evenly across several teeth, reducing the risk of overloading any single tooth and potentially leading to less wear and tear or damage.
24
Q
Facebow eg 2x
A
Denar Slidematic Facebow- arbitary hinge axis FB
kinematic facebow req for FMR on a fully adjustable articulator
25
Incisal display in repose
* Female
* Male
2-4mm
1-2mm
Varies based on gender, age,length of maxillary
lip
26
radiograph to see if violate of Biologic width =Measure from pr.....
Measure from proximal gingival margin to alveolar bone crest , if <3mm, may need CL
superimposition reduce accurage of PA
27
CLOSER the restorative margins to the base of the sulcus, the GREATER THE 5x
1* Gingival inflam.
2* Gingival recession + alv bone loss
3* CAL
4* Probing depths
5 Number of spirochetes, and bacteria
28
Crown lengthening indications:- 4As
1.ACCESS=Margins, fractures, caries, impression taking
2. AESTHETIC -excess gums,thick fibrotic
3. AXIAL wall height retention
4. ACHIEVE BW
29
FACTORS TO CONSIDER DURING Crwn Lengthening
1esthetics
2whole tooth
3root
4crown
5 soft tissue
1 Esthetics- ging overgrowth
whole tooth
2 clinical tooth length, c:R 1:1- ideal 2:3
3 mobility short and conical
Root
1Proximity [if remove interprox. bone, black triangles -Extrusion/exo
2Root perforation [cervical in endo]
3 Exposure of furcation with short root trunk- higher perio risk
Crwn
1 Adequate coronal struc R+R [ mini. Axial height= 3mm ant and pm; 4mm molar]
2 Ferrule 360 deg 1-2mm in height 1mm in width
Ferrule is defined as the vertical band of tooth structure at the gingival portion of crown preparation. Ferrule Effect is the encircling of metal band that embrace the gingival portion of crown preparation that provide protection against#
Soft tissue
1 BW+ sulcular depth
2 Thickness of soft tissue /ridge morphology
30
Retention & Resistance Form for crown prep -
Minimum axial wall height: ant, premolar +molar
Anterior teeth & premolars: 3mm
Molars: 4mm (Goodacre 2001)
31
HEALING AFTER CL
wait at least
90 days; for sufficient healing to reestablish periodontal attachment before crown/bridge done
Anterior teeth =min 3 mths; Ideally 6mths
Posterior teeth min 4-6wks [not in esthetic zone- that usu 3months]
32
Perio-restorative interface is any area of contact between a fixed prosthesis and periodontal tissues.
Determined by prosthetic design 5x
1 Placement of finish lines- supra/subg
2 Adapation of margins -x marg leakage/overhang
3 Emergence profile=Axial contour that emerges from gingival sulcus which is either straight/concave; x overcontoured
4 Embrassure space- x large
5 Pontic design
33
ID Papillary Height Determined by 3x
1 Level of bone
2 Biologic width
3 Form of gingival embrasure
34
free gingival margin to alv bone crest distance
normal height of papilla to alv bone
effects of contact pt on whether papilla fill up the space
Free gingival margin averages 3mm above the underlying buccal bone.
Tip of papilla averages 4.5-5.0mm above the interproximal bone.
Thus, Gingival level of interproximal tooth contacts ≤5mm to the alveolar bone: Papilla fills the space.
6mm away from bone: >56% papilla fill.
7mm away from bone: >37% papilla fill.
35
Causes for Open Embrasures 3x
1 Papilla height inadequate due to bone loss.
2 Interproximal contact too high coronally.
3 Tooth shape is excessively tapered.
36
Design of pontic important in
preventing inflammation
ideally- in general have
connector shld have
ideally +ve tissue contact, convex intaglio [inner] surface
Connector: adequate occlusogingival dimension for strength,adequate clearance for hygiene access
37
furcation flutes added into crwn prep design; yes or no, why
yes, avoid plaque retention
38
contraindications of root resection 3x
1. Fused roots
2. Furcation too apical:too little bone to support remaining roots. Have to be at coronal 1/3
3. Excessive alveolar support has been lost uniformly
39
Sucessful restoration-periodontally weakened teeth-aided by creating occlusal scheme with: 3x
1Canine protected articulation
2 Decreased vertical overlap
3 Flattened posterior cusps
40
post purpose 3
vs
core purpose 2x
1. inc in intraradicular retention- resist vertical dislodging forces-long and active [engage walls] degisn [vs passive-retained by luting agent only]+ parallel>taper design
2 mainly to retain the core in a extensively broken down tooth
3 antirotational features - resist rotational forces
1 Replacement of lost tooth structure
2 achieve conventional tooth prep => increase axial wall height to increase the retention
41
displacement of gingival tissues via ...
**mechanical**-retraction cord and **chemical**-astringent and hemostatics [aluminium chloride/ferric sulphate/Epinephrine impregnated cord*] means of displacement of gingival tissues.
42
Double Cord Technique
First cord placed deep in sulcus, compressive and prevents GCF from oozing into the crevice.The second cord serves to deflect–driving gingival tissues
away from the finish line and is removed shortly before impression making.
Choose appropriate size -eg thin- shallow sulcus
repeated use-displacement cord->recession can result
Avoid leaving cords in sulcus >10mins=>tissue destruction , at least 4 mins for accurate impression taking.
43
Electrosurgery/electrocautery
Purpose:
Features:
Safety Note:
Purpose: Used for minor tissue removal before making dental impressions.
Features: Coagulates as it cuts, allowing immediate impression making; removes the inner epithelial lining of the gingival sulcus, which improves access but can cause gingival recession.
Safety Note: Must not contact metal instruments to avoid burns or electric shock.
44
Contraindications Electrosurgery/electrocautery 3x :
-pacemakers-electronic medical devices,
-radiotherapy patients with poor healing abilities or
-thin attached gingiva.
45
gingival architecture preservation by ... extraction & ... pontic design
by Atraumatic extraction & Ovate pontic design
Scalloped architecture=interproximal bone MZ be preserved to allow proper papilla formation
46
PRINCIPLES of PONTIC SELECTION Priorities:3x
1. Mechanical strength
2. Access for hygiene
3. Esthetics -Emergence profile with or w/o mucosal contact
47
pontic design with mucosal contact
full Ridge lap/ saddle- concave/ x sanitary/inf/ ulcers
Modified ridge lap -Gingival surface convex , buccal is concave surface
Sanitary & Ovate-Most aesthetically appealing+Best emergence profile;Convex undersurface;Easiest to clean
Conical-only 1point of contact- suitable for thin ridge and post teeth
48
pontic design w/o mucosal contact
Sanitary(hygienic)
Modified sanitary (hygienic)- gingival portion shaped like archway
49
Etched-Cast Resin Bonded FDP (Micromechanical Retention – Maryland Bridge)
Involves...
advantages 3x
Involves the electrolytic etching of cast base metal retainers.
1Improved retention due to strong bond between resin and etched metal.
2Retainers can be made thinner and are still robust against flexing.
3Oral surface of the cast retainers is highly polished, helping resist plaque accumulation, compared to perforated restorations.
50
**DIRECT adhesive bonding** in resin-bonded fixed dental prostheses (FDPs), also known as adhesion bridges, involves
steps...
involves the use of adhesive systems to secure the metal part[Nickel] prosthesis to the enamel tooth structure.
1 particle abrasion on Metal Surface to create micromechanical retention sites, wash, dry
2 primer
3 Enamel Etching, rinsing
4 resin cement application.
Adhesive Resin Systems:contains methyl methacrylate polymer powder and liquid modified with adhesion promoters such as 4-META (4-methacryloxyethyl trimellitic anhydride) and MDP (10-methacryloxydecyl dihydrogen phosphate).
Panavia 21 cement and alloy primer;
Multilink cement and multilink primer
self adhesive system; rely x unicem
51
Advantages of Resin-Bonded Bridges (RBBs): 7x
1 Preservation of tooth structure and pulpal health due to minimal tooth preparation.
2 Favorable for periodontal health as less tooth structure is removed+ supragingival margins
3 Prosthesis fabrication is relatively simple and cost-effective.
4 In case of failure, rebonding of the bridge is possible.
5 Aesthetically satisfactory, especially for anterior teeth.
6 Can serve as transitional bridges for young patients before implant placement.
7 Less invasive compared to conventional FDPs.
52
Disadvantages of Resin-Bonded Bridges: 6x
1 Enamel modification is required for bonding, which may not be ideal for all patients-AI,Ehypop.
2 Generally, RBBs have reduced longevity compared to conventional FDPs.
3 Correcting space discrepancies can be difficult with RBBs.
4 Not suitable for patients with heavy occlusion or those who bite on hard foods.
5 High annual failure rate due to debonding.
6 Positional changes due to bone growth in young patients can affect the fit and longevity of the bridge.
53
Indications for Resin-Bonded Bridges: 6x
1 Suitable for short-span replacements, particularly in anterior regions.
2 Ideal for well-aligned teeth+ in children
3 sound teeth- minimal prep is preferred
4 moisture control can be achieved
5 good periodontal health- no mobility
6 sufficient crown height
54
Contraindications for Resin-Bonded Bridges:7x
1 long-span FPDs with high stress
2 parafx habits and area with heavy bite forces, such as mandibular molars.
3 short clinical crowns
4 Not suitable for areas with compromised enamel due to hypoplasia or demineralization.
5 difference in mobility between abutment teeth
6 deep vertical overlap
7 nickel allergies-> use noble alloy with 30-50% incr in thickness [>stiff] dt lower modulus of elasticity
55
metal selection for the PFM metal framework 3 main types
High Noble Metal Alloys: These alloys contain a minimum of 60% by weight of noble elements, with at least 40% being gold. Examples include Gold-Platinum-Palladium (Au-Pt-Pd) alloys. They are biocompatible.
Noble Metal Alloys: at least 25% by weight of noble metal but no requirement for gold %. Examples include Palladium-Silver (Pd-Ag), and Palladium-gallium (Pd-Ga) They offer a balance between cost and performance.
Predominantly Base Metal Alloys: contain less than 25% by weight of noble metal such as Nickel-Chromium (Ni-Cr), Cobalt-Chromium (Co-Cr), and Titanium-based alloys. They are generally more cost-effective and have high strength, but may not offer the same level of biocompatibility as noble metal alloys.
56
Rigid connectors in Fixed Dental Prostheses (FDPs) are the components that join the .... to form a continuous structure. They are the most commonly used type of connector in FDPs. Rigid connectors can be fabricated through ....
individual retainers and pontics together
casting, soldering, or welding
57
Rigid connectors are indicated when abutment preparations have a common ....., allowing for a one-piece casting without any..... the pontic and the retainers. They are suitable for ....
path of placement
movement between
short-span FDPs where minimal flexing occurs.
58
However, in long-span or complex FDPs, rigid connectors may inhibit .... and cause .... of the FDP. solution? use....
mandibular flexure
stress that could lead to dislodgement or fracture
Nonrigid connectors /segmenting the FDP into shorter components maybe more appropriate.
59
Munsell Color System 3 main component
hue, value, and chroma.
Hue refers to the type of color (e.g., red, green, yellow), system arranges hues in a circular format.
Value indicates the lightness or darkness of a color on y-axis.
Chroma describes the intensity or saturation of the hue; by radiating out from centre of wheel.
60
Shade Selection Steps Clinically: 7x
1 Initial Hue Selection: Begin by choosing the closest hue, often using the cervical region of canines where chroma is highest as a reference point.
2 Value and Chroma Adjustment: After selecting the hue, adjust for the correct value (lightness or darkness) and chroma (saturation) using a shade guide like the Vitapan 3D Master.
But manufacturer recommends, selection of value first at arms length,then chroma then hue [more red or yellowish]
3 Environment and Lighting: Ensure the environment has neutral-colored walls and balanced, color-corrected lighting to prevent metamerism. Remove any brightly colored clothing or makeup that could influence perception.
4 Tooth Preparation: Clean the tooth to be matched, removing any stains if necessary. Use cheek retractors for an unobstructed view.
5 Shade Matching: Match the shade quickly (less than 5 seconds) to avoid eye fatigue, placing the shade tab directly next to the tooth. Squinting can help discern value by reducing the influence of color.
6 Confirmation: Confirm the shade selection at the beginning of the visit under several lightings and helpful to confirm with an auxiliary staff member.
7 Final Selection: If an exact match is not found, select a shade tab with lower chroma and highest value[White=10,black is zero], as extrinsic characterization can adjust these aspects later.
61
What makes a good smile is determined by several key factors: 4 x
1 Proportion: The most attractive smiles often have maxillary incisor height/width ratios close to a 75% to 78% range. The golden proportion (1.618:1) is a guideline but does not apply to all patients.
2 Balance: A balanced arrangement of teeth implies stability and permanence. The dental midline should appear centered and balanced with the rest of the face ideally. Studies suggest that a mean threshold for acceptable dental midline deviation is around 2.2 ± 1.5 mm.
3 incisor anglation- M is acceptable, avoid Distal ∠
4 Smile arc=the curvature of the incisal edges of the maxillary teeth relatively similar to the lower lip for an attractive smile.
62
RPA system consists of
mesial Rest, distal Proximal Plate, and Akers' clasp (also known as a circumferential clasp) instead of an I-bar clasp.
The Akers' clasp encircles the tooth, providing retention by engaging an undercut on the abutment tooth. This system is often used when an I-bar is not suitable due to anatomical limitations or esthetic concerns.
63
The Reverse Circlet Clasp is indicated for situations where ....
characteristics...
This clasp design controls stresses delivered to the abutment upon loading of the removable partial denture by allowing the clasp's ...
infrabulge clasp is contraindicated, and an there is a distofacial undercut on an abutment tooth .
It has a mesial rest and a cast circumferential clasp engaging the distofacial retentive undercut.
retentive terminus to move into an area of greater undercut, thus minimizing torsional stress. However, it is contraindicated when there is inadequate occlusal clearance, as the clasp needs to cross the mesial marginal ridge of the abutment tooth.
64
Cast Combination Clasp is an alternative...
, featuring a
to the RPI system
cast reciprocal element; a DISTAL rest and a round **wrought wire retentive clasp**, which is more **flexible** for its stress-breaking action. The cast reciprocal arm is rigid, effectively resisting lateral forces and reciprocating the force exerted by the retentive wrought wire during placement or removal of the partial denture.
65
Rest Seat Preparation/importance:
fx of rest lao chun fai man boob is REally enormous large in oct
1 Ensure LOAd transmission along the longitudinal axis of the tooth.
2 Avoid Cervical impingement.
3 Prevent Food traps
4 Maintain proper clasp-tooth position,
5 bracing-cingulum rest on canine,
6 IR
7 Prevent Extrusion
8 improving occl contact -with overLAys.
66
enamel modification for RPD besides for rest prep we adjust the ...3x
if too low..
If too high:
1Survey Line Adjustment:
If too low: Add retentive undercut with CR or align if too tilted w/- orthodontics.
If too high: Adjust to lower to eliminate interference.
2Occlusal/Incisal Plane Adjustment:
to correct uneven occlusal plane for esthetic reasons.
3 Occlusal Channel:
Create a path for the C clasp to cross occlusally to the buccal surface.
67
Bracing: vs
Indirect Retainers:
Bracing: Provides resistance to horizontal components of masticatory forces that tend to displace the denture in antero-posterior and lateral directions. Bracing occurs only when the denture is fully seated and is achieved through components like reciprocal arms [above survey line] and minor connectors.
Indirect Retainers: Specifically designed to resist vertical movement of the denture base away from the tissue, particularly in distal extension RPDs. Located as far from the primary fulcrum line as possible to maximize their effectiveness.
68
An immediate replacement denture is a prosthesis that is fabricated prior to the ...and inserted...
This allows the patient to have a .... prosthesis during the healing period. After healing, which typically takes a few months, take .....
This step is crucial as the immediate denture will likely need ......due to .....
extraction of the remaining teeth and is inserted immediately after the extraction.
functional and esthetic
final impressions for a more accurate and stable denture.
adjustments or replacement
residual ridge resorption post-extractions
69
DIRECT RETAINER EXAMPLES 8x-
1. Clasps (C-clasps and roaches)
2. Guide planes
3. Soft tissue undercuts (Flanges)
4. Fitting surface of denture base -- Cohesion adhesion
Anatomical undercuts: Proper engagement of flange into soft tissue and bony undercuts without causing discomfort or trauma enhances the stability and retention of the denture.
Border Sealing: Effective border molding to capture the functional depth and width of the vestibule helps in improving suction.
5. Muscular control-
6. Magnets
7. Precision attachments
8. Implants
70
Advantages of providing an immediate replacement denture include:5x
1 Preservation of esthetics and function during healing period
2 Protection of the extraction sites
3 Psychological benefit/ avoid social embarrassment
4 Adaptation: speech and mastication habits more quickly compared to waiting for a conventional denture after healing.
5 Minimization of the need for multiple appointments, impression taken, then tooth is removed from the cast to add tooth to existing denture.
71
Disadvantages of providing immediate replacement denture for patients include: 3x
1 Potential need for adjustments and relining (e.g., GIC Reline or Kooliner chairside) as the bone remodel and healing progresses-affect fit =first 6 weeks- 3months
2Potential for Complications: If does not fit well, irritation and discomfort occurs, and in some cases, it may impair the healing process.
3 Increased cost for fabricationand time for adjustments
72
eg mandibular major connectors available 6x
1.lingual plate-vertical plate extending from the lingual bar up to cover the cingula ant teeth
2.lingual bar, [8mm in Vest. depth]
3.sublingual bar-more lingually and inferiorly than the lingual bar
4.dental bar,
5.Kennedy bar aka continuous clasp/bar, 6.labial bar-Md tori is inoperable, and severe L inclined tooth, less common due to aesthetic concerns and lip irritation
73
why RPD is done?/factors to consider 6x
1Replacement of Missing Teeth:
=Mastication: Restores chewing ability, improves nutrition
=Speech: Helps in clear articulation, especially with missing anterior teeth.
2Positional Stability:
Prevents shifting and supraeruption of remaining teeth.
Maintains alignment, prevents occlusal disturbances and periodontal issues.
3 Distribution of Chewing Forces evenly across the dentition.
Reduces load on natural teeth, preserving their structure and health.
4 Aesthetics:
Supports lips and cheeks, preventing a sunken appearance.
Enhances facial aesthetics, filling in spaces of missing teeth.
Improves the patient's smile and confidence.
5 Economical Solution:
More cost-effective compared to single implants (SIC) or bridges.
Suitable for patients with multiple missing teeth.
6 Psychological Benefits:
Provides a sense of normalcy and well-being.
74
rule of thumb, abutments can carry its own
masticatory load + 1.5 replacement units
K cIV -LONG SPAN
LACK OF MUCOSAL SUPPORT [MAJOR CONNECTOR- NOT PALATAL PLATE WHICH ABLE SUPPORT MORE TEETH]- LACK OF COVERAGE OF ENTIRE PALATAL SURFACES
broader residual ridge, the better the load distribution.
75
Purpose of Rest Seat Preparations:
1 Produce Favourable Tooth Surface for Support: Ensure vertical loading of the tooth.
2 Create a stable foundation for the denture.
3 Prevent Interference with Occlusion
4 Reduce Prominence of a Rest and more comfortable.
5 Prevent Tooth Migration:
Keep remaining teeth in their proper positions.
5 Improve Accuracy of Fit:
Ensure a precise and comfortable fit of the denture.
6 Aid in Self-Cleaning of Tooth Surface
76
Consequences of Absence of Rest Seats:
On Unprepared Surface:
1 Rest stands out prominently.
2 plaque retentive.
3 Potential to irritate the tongue.
4 Can interfere with occlusion.
5 Specific to Cingulum Rests: Forces applied in a labial direction and tends to slide down the tooth under occlusal load.
77
Discuss the assessments of a fully edentulous patient before you commence on the rehabilitation with removable complete denture. 15x
1 previous denture h/o/ problems/ satisfaction
2 MHs: Diabetes, cardiovascular diseases, osteoporosis, Parkinson’s disease (affects manual dexterity).
Medications: causing xerostomia or altered oral mucosal health (e.g., beta blockers, ACE inhibitors, chemotherapy).
Nutritional Status: Good nutrition for healing and healthy mucosa.
Deficiencies: Vitamin B12 or C deficiency increases ulcer risk.
Allergies:
Assess for allergies to denture materials to ensure safe material selection.
3 Hygiene and Maintenance:
Assess patient’s capability and willingness to maintain oral hygiene and denture care.
4 Extraoral and Intraoral Examination
Orofacial Muscles and TMJ:
Evaluate: Muscle strength, TMJ function (impact on denture stability and comfort).
5 Ridge Anatomy and Health:
Evaluate: Size, shape, irregularities of alveolar ridges.
Concerns: Flabby ridges, undercuts, tori, sharp bony spicules.
Note: Significant ridge height reduction, especially in the first year of denture wearing.
Soft Tissue Health:
Look for: Signs of inflammation, pathology, oral cancer.
Pre-existing Conditions: Address oral candidiasis, denture-induced hyperplasia before fabrication.
6 Muscle and Frenal Attachments:
Consider impact on denture border extension.
7 Salivary Flow:
Assess for xerostomia, which is crucial for denture retention and oral health.
8 Esthetic and Functional Considerations
Facial Esthetics and VDO (Vertical Dimension of Occlusion):
9 Assess: Facial analysis, need for VDO adjustments.
Components: Occlusal plane orientation, lip support, teeth (number, size, shape, color, position), flange design.
Interarch Space:
Ensure adequate space for prosthetic components without compromising function or esthetics.
10 Phonetics:
Evaluate: Speech to determine placement in neutral zone.
Key sounds: F, V (incisal length), th (cingulum contour), S (smallest speaking space of 1mm).
Psychological and Social Evaluation
11 Patient Expectations:
Discuss expectations regarding appearance, function, and comfort.
12 Adaptability:
Assess psychological readiness, cognitive function, previous denture experiences.
Note: Conditions like ataxia;Parkinson’s affect neuromuscular coordination.
13 Caregiver Attitude:
Consider involvement in patient care and support.
Radiographic Assessment
Bone Quality and Quantity:
14 Use radiographs to evaluate bony structures, identifying significant resorption or pathology.
Pathologies:
Detect underlying conditions that may require pre-prosthetic surgery or special consideration.
15 Preliminary Impressions
Accurate Impressions:
Create study models for custom trays to capture detailed anatomy.
78
if excessive viscosity, there will be
discontinuity in the film
(bubbles causing air to flow in more readily)
79
Preliminary Impressions: Use
Final Impressions: Use
stock trays + alginate
custom trays + elastomeric materials for detailed capture of ridges and soft tissues
80
Obtaining Adequate Impressions in Flabby Upper Anterior Ridge and Severely Resorbed Lower Ridge
Challenges
Rationale for Impression Techniques
Upper Ridge
Upper Ridge (Flabby Maxillary Upper Anterior Ridge):
Excessive pressure **distorts** flabby tissue and Compression causes discomfort.
Lower Ridge (Severely Resorbed and Flat):
Difficulty in obtaining adequate support and stability.
Overextension: Inaccurate border molding may lead to overextended denture borders.
(Selective Pressure Technique):
Two-Step Process: Use light body impression material for flabby areas, heavier body for firm areas.
Custom Tray: Fabricate with relief areas over flabby tissues to minimize compression.
Goal: Ensure accurate impression without displacing mobile tissue; avoid undue pressure+ comfort.
Lower Ridge (Mucostatic and Functional Techniques):
Mucostatic Technique: Record resorbed ridges without damaging fragile tissues.
Functional Technique: Use low-viscosity materials like ZOE to capture tissues in a functional state.
Border Molding: Perform careful border molding to accurately capture border tissues.
81
Ferrule is defined as the ..
Ferrule Effect is the
vertical band of tooth structure at the gingival portion of crown preparation.
Ferrule Effect is the encircling of metal band that embrace the gingival portion of crown preparation that provide protection against#
82
Protemp Crown is composed of
LC resin- bis-GMA, and dimethacrylate resin. Fumed silica fillers and Silanated zirconia-silica fillers are used to impart physical strength, and wear resistance.
83
Causes of Dislodgement and Breakages of Provisional Crowns and Bridges 9x
how to prevent
1 Inadequate Retention and Resistance Forms: **height, ratio , taper**
Insufficient preparation design (short axial wall height=OC/FL RATIO 0.4 or higher, molar; lower than 0.4-poorer resistance to dislodgement crown)/inadequate total occlusal convergence. Goodacre 2001
Preventive Measure: Ensure proper taper (4-8° each surface) and sufficient axial wall height (minimum 4 mm for molars, 3 mm for other teeth). Use auxiliary resistance features [axial grooves or boxes, preferably on proximal surfaces] if needed.
2 Poor Material Selection or Handling:
Use of luting materials with inadequate strength or improper mixing.
3 Inadequate Thickness of tempMaterial:
Thin areas prone to fracture under normal masticatory forces.
Preventive Measure: Ensure sufficient bulk in areas of occlusal contact and cusp tips.
4 Improper Occlusal Adjustment:
High spots or premature contacts leading to fractures.
Preventive Measure: Adjust occlusion to ensure even distribution of forces.
5 Poor Marginal Adaptation:
causing dissolution of temporary cement and poor retention.
Preventive Measure: Fabricate precise margins and take accurate impressions.
6 Lack of Proper Support: BCZ edentulous space larger or smaller than normal tooth size->Inadequate support from underlying tooth structure or adjacent teeth.
Preventive Measure: Ensure proper support and contact with adjacent and opposing teeth.
7 Patient Factors:
Parafunctional habits (e.g., bruxism, clenching) and dietary preferences.
Preventive Measure: Educate patients, consider night guards, and advise against hard/sticky foods.
8 poor moisture control.
Preventive Measure: follow proper cementation protocols.
9 Cleansable tissue - pontic design
84
[Temp-Bond™ is a
vs Reinforced ZnOE or eugenol free ZnO
self-curing zinc-oxide eugenol-based temporary cement - ease of removal
with higher strength = tooth prep lack retention; long term use; parafunction
85
Considerations for Restorability and Prognosis of Endodontically Treated Central Incisor in Adolescents 8x
1 Remaining sound Tooth Structure:
Restoration: Direct restoration for sufficient structure; post and core if crown is needed.
2 Root Development; dentinal wall thickness, and root robustness.
Consider: C:R ratio and post/core indications if root is underdeveloped.
3 Occlusal Considerations:
Assess occlusal forces and lateral movements.
Design: Ensure restoration resists lateral and shearing forces.
4 Esthetics:
Ensure acceptable color match, shape, and alignment with adjacent teeth.
5 Orthodontics:
Align and position tooth in the arch before restorative plans.
6 Periodontal Health:
Assess and manage periodontal disease or recession before restoration.
Timing: Wait until gingival maturity (20s) for final restoration.
7Endodontic Treatment Quality:
Evaluate apical seal and integrity of root canal filling.
8 Patient Factors:
Consider oral hygiene, compliance, dietary habits, and parafunctional habits.
86
Restorative Treatment Options for Endodontically Treated Central Incisor in Adolescents
1Composite Resin Restoration:
For adequate remaining tooth structure.
Benefits: Minimally invasive, cost-effective, good esthetics.
2 Porcelain Veneer:
For durable, esthetic solution with adequate tooth structure.
Benefits: Excellent color match, resistance to staining.
3 Full Coverage Crown:
For significant loss of structure.
Material: pfm, zirconia layered with porcelain) offer durability and strength but Emax/ zirconia for >conservative prep.
4 Post and Core with Crown:
For insufficient coronal tooth structure.
Benefit: Post provides retention, core supports final crown.
87
Parafunctional habits-> more forces ; less ...
neuromuscular feedback - no proprioceptive reflex - to non axial loading -> TMJ problems
88
factors to consider when deciding on the choice of materials for:
Single Crown 11x
1 Esthetic Demands:
Anterior: High esthetics-translucency and color matching; use EMAX (lithium disilicate) or leucite-reinforced ceramics.
Try in paste with [Variolink]= better match shade
Posterior: Durability; use zirconia.
2 Strength,+flexural strength and Durability: Zirconia, densely sintered alumina [polycrystalline-procera].
3 Wear Resistance: Avoid excessive hardness to prevent wear on opposing teeth.
4 Tooth Preparation:
Conservative Preparation: Zirconia allows less tooth reduction.
5 Preparation Design: Avoid undercuts; ensure adequate thickness without excessive reduction.
6 Restoration Longevity:
7 Occlusal Considerations:
Stable MI - no TMD
Parafunctional Habits: Use durable materials (e.g., monolithic zirconia) for bruxism/clenching.
8 Biocompatibility: not cause allergic reactions.
9 Cementation Protocol: Adhesive bonding
10 Core Support:
Ensure compatibility with the core material for endodontically treated teeth.
11 Patient Preference and Cost:
Consider patient's choices and budget.
89
some Tooth Preparation considerations = ceramic anterior teeth:
1Conservative Preparation
2 Design: avoiding undercuts and ensuring enough thickness for material strength without excessive tooth reduction.
3 Position and margins 0,5mm subg
4 Emergence profile ideal and Embrasure space - self cleansing; simulate natural contour of teeth- IF OVERCONTOURED - ging infl [eg horizontal ridge at gingival third of crown above furcation flute will be plaque retentive]
5 Axial Thickness:
Feldspathic and zirconia ceramics can sometimes allow for more conservative preparations (0.3mm- 0.5mm).
Reinforced glass ceramics like leucite-reinforced and lithium disilicate generally require slightly more tooth reduction (1.0mm- 1.5mm) to accommodate the material thickness needed for strength and esthetics.
90
factors to consider when deciding on the choice of materials for: 3-Unit Fixed Dental Prosthesis (FDP)
1 Esthetic and Functional Requirements:
Anterior: High esthetics; use lithium disilicate.
Posterior: Strength and durability; use zirconia.
2 Span Length and Occlusal Forces:
Use zirconia for longer spans and higher occlusal forces.
3 Load Management:
Abutment Health: Use stronger materials for compromised abutments.
Ante's Law: Ensure root surface area of abutments equals or surpasses that of replaced teeth.
4 Connector Design:
Ensure adequate size and design for stress distribution.
5 Esthetics: Match translucency and appearance to natural teeth.
6 Speech:Avoid lisping ["s"]; ensure proper "f", and "v" sounds.
7 Occlusal Scheme: Ensure one stable MI position; direct forces axially.
8 Technique Sensitivity:
Consider clinician's skill and lab capabilities.
9 Marginal Fit:
Precise fit to prevent plaque accumulation and caries.
10 Wear Resistance:Similar wear resistance to natural enamel.
11 Biocompatibility:
12 Patient Preference and Cost.
91
Conventional PVS vs. Digital Impressions
Conventional PVS Impression:
Advantages: High accuracy, reliable, captures fine details.
Disadvantages: Potential patient discomfort, risk of distortion, requires timely pouring, technique sensitive.
Digital Impression:
Advantages: Quick, comfortable, instant transmission to lab, easy storage, immediate feedback.
Disadvantages: High initial investment, challenging to capture sub-gingival margins if not exposed properly. LMO
92
Discuss the factors of consideration for the following:
Prefabricated Post and Core
1 Tooth Structure:
Assess remaining dentin thickness for support-wide post INC risk root fracture.
2Canal Anatomy: Fit snugly without excessive dentine removal.
3 Retention and Stability:
Post Design: Parallel designs offer better retention.
Length and Diameter: Occupy at least two-thirds of the canal length; sufficient dentin must remain <1/3 diameter.
4 Material: Choose based on strength, esthetics, and compatibility (e.g., SS, titanium, fiber-reinforced resin post).
Fiber posts preferred for anterior regions due to esthetics and similar elasticity to dentin.
5 Fit and Adaptation:
Minimize voids and gaps for retention and longevity.
6 Occlusal Forces
Fiber posts suitable for lower occlusal loads
7 Ease of Use:
Easier and quicker to place than cast posts.
8 Cementation: Use adhesive resin cements for bonding.
9 < Resistance to Rotational Forces vs cast post:so, Incorporate anti-rotation features.
93
Indications: Cast Post and Core
and discuss the factors of consideration :
=For teeth with significant structural loss needing maximum strength and custom adaptation.
1 Custom-fabricated to fit root canal morphology, beneficial for irregular shapes or significant coronal loss.
2 Tooth Structure:
94
factors of consideration to decide on the restorability of a broken upper canine 13x
1. Extent of Structural Damage: Assess remaining sound tooth structure; < 1mm ferrule indicates poor prognosis.
Fracture Location and Direction: Favorable if confined to the crown; vertical fractures below the gum poor prognosis.
2. Endodontic Condition
Pulp Vitality: Check for pulp exposure or need for endodontic treatment.
Previous RCT: Consider prognosis; may need post and core for support.
Root Health: Favorable if roots are healthy and intact.
3. Periodontal Health: Evaluate for disease; ensure margins respect biological width.
4. Occlusal Considerations: Ensure restored tooth withstands occlusal forces and contributes to a stable bite.
5. Esthetics: High esthetic demands due to visibility during speaking or smiling.
6. Biomechanical Considerations
Biomechanics: Consider tooth length, restoration thickness, and dislodging forces.
7. Restorative Material
Material Choice: Based on strength, esthetics, and wear characteristics (e.g., emax, zirconia).
8. Patient Factors
Oral Hygiene: Assess patient’s hygiene, dietary habits, and parafunctional habits.
Prosthodontic Design: Ensure self-cleaning emergence profile and respect biological width.
9. Financial Considerations
Cost: Consider patient's financial situation and restoration costs.
10. Treatment Planning
Comprehensive Plan: Incorporate overall dental needs, patient expectations, and follow-up ability.
Options: Adjunct treatments (e.g., ortho extrusion, surgical CL).
11. Direct vs. Indirect Restorations
Minor Fractures: Direct composite bonding.
Significant Damage: Indirect restorations (crown, post+core, crown).
12. Failure Rates and Complications
Restoration Risks: Understand potential failure rates and complications.
13. Implants or Bridges
Alternative Options: Consider if natural tooth prognosis is poor.
95
Provisional Cementation eg and characteristics: 3x
1 Zinc Phosphate cement with a long track record.
2 self curing Zinc Oxide-Eugenol (ZOE): Tempbond -Excellent bond strength, yet easy-to-remove when desired
3 Zinc Polycarboxylate: Provides mechanical bond to tooth structure.
96
Definitive Cementation of FDP 5x
1 Reinforced ZOE: strength; biocompatibility.
2 Glass Ionomer Cement (GIC)
3 Resin-Modified Glass Ionomer Cement (RMGIC): Improved esthetics and strength compared to GIC.
4 Self-Adhesive Resin Cement:
5 Resin Cement (e.g., Panavia 21):
97
Resin Cement (e.g., Panavia 21):
Components:
Advantages:
Disadvantages:
Indications:
Contra-indications:
Components: Bis-GMA,silane (coupling agent); silanated filler (silica/barium glass) particles; Catalysts
Advantages: High bond strength to e,d, metal alloys, ceramics&CR, good esthetics, resistance to solubility; Anaerobic-curing,anaerobic curing-in the absence of Oxygen btw contact surfaces; reliable with self-etching PRIMER[extra step]. If etch-uncut enamel
Disadvantages: Technique-sensitive, potential post-cementation sensitivity.
Indications: All-ceramic, resin, metal restorations, high esthetic areas.
Contra-indications: Methacrylate monomer allergies, poor moisture control situations.
98
Self-Adhesive Resin Cement:
Components:
Advantages:
Disadvantages:
Indications:
Contra-indications:
Components: Methacrylate resins, filler particles[Silica, zirconia/ barium glass particles=strength and wear resistance], acidic monomers=10-MDP [self-etching capability].
Activators/Catalysts: Dual-cure system with photo initiators, camphorquinone for light curing and chemical activators for self-curing.
Inhibitors: Such as BHT (butylated hydroxytoluene) to prevent premature polymerization.
Stabilizers and Modifiers: To control setting time and improve handling properties.
Advantages: Ease of use[no need for separate etching, priming, or bonding steps], good mechanical properties-high compressive and tensile strength
Disadvantages: Technique-sensitive, potential post-op sensitivity[if x fully cured], higher cost.
Indications: All-ceramic, resin, metal restorations, posts, and prefabricated pins.
Contra-indications: Specific aesthetic adjustments, increased film thickness issues,allergies
99
Glass Ionomer Cement (GIC)
Components:
Advantages:
Disadvantages:
Indications:
Contra-indications:
Components: Fluoroaluminosilicate glass powder, polyacrylic acid.
Advantages: Fluoride release, chemical/ionic bond to tooth, biocompatibility, low COTE
Disadvantages: Less aesthetic, lower mechanical strength, moisture-sensitive.
Indications: Metal or PFM crowns and bridges, high caries risk areas.
Contra-indications: Veneers, all-ceramic restorations needing high esthetics, high bond strength situations.
100
Resin Matrix: Typically includes ...
Bis-GMA (bisphenol A-glycidyl methacrylate), UDMA (urethane dimethacrylate), or TEGDMA (triethylene glycol dimethacrylate)
as the base resin
101
zinc Phosphate Cement: Consists of a powder ... and liquid...
zinc Phosphate Cement: Consists of a powder (zinc oxide, magnesium oxide) and a liquid (phosphoric acid, water).
102
Resin-Bonded Prosthesis
Expected Survival: Average survival rate:
Factors Causing De-Bonding:
5-10 years.
1Poor tooth preparation.
2Improper bonding technique; Moisture contamination.
3Excessive occlusal forces.
4Poor prosthesis fit.
5 Material fatigue.
103
Margin Preparation Designs for Full Coverage Indirect Restorations
types
indication
1 Chamfer:
Indications: Full metal crowns (0.5mm), PFM with metal collar (0.5mm).
Advantages: Minimal tooth removal, good marginal adaptation, adequate bulk for restorative rigidity.
Disadvantages: risk of lip formation with deep chamfers.
2 Shoulder: porcelain butt joint
Indications: PFM with butt joint(1.0-1.5mm), all-ceramic crowns (0.7-1.5mm).
Advantages: Maximum aesthetics and crown strength, prevents overcontouring.
Disadvantages: Least conservative, can weaken the tooth, sharp internal line angle predisposes to fractures.
3 Heavy chamfer (Rounded): subgin 0,5mm
Indications: Full coverage crowns needing maximal strength and aesthetics.
Advantages: Maximum aesthetics and crown strength, less stress than classic shoulder.
Disadvantages: Less conservative than chamfer, more stress than chamfer.
4 Shoulder with Bevel:
Indications: Posterior PFM with supragingival margins.
Advantages: Maximal crown strength, less stress than classic shoulder.
Disadvantages: More stress than chamfer, requires a metal collar affecting aesthetics.
5 Knife Edge:
Indications: Not recommended
Advantages: Minimal tooth removal.
Disadvantages: Poor marginal adaptation for PFMs, overcontouring risk.
104
Bevel (Finishing or Contrabevel):
indicated in:
Adv
disadv
Indications: Maxillary partial coverage restorations and inlay/onlays.
Advantages: Better marginal adaptation, minimizes marginal discrepancy.
Disadvantages: Poor marginal adaptation for direct-bonded PFMs
105
Factors to Consider for Margin Design on Tooth 21
1 Esthetic Considerations:
Visibility in the smile line and patient's esthetic preferences.
Size, shape, and characteristics of tooth (Golden proportion 1:1.618).
2 Periodontal Health:
Condition of gingival tissues and presence of periodontal disease.
Preparation must respect gingival tissue and biological width.
3 Structural Integrity:
Amount of remaining tooth structure, including previous restorations, caries, or fractures.
Preserve as much healthy tooth structure as possible.
4 Material Selection:
Type of restorative material influences margin design.
Chamfer for zirconia, heavy chamfer for Emax (0.8mm).
5 Endodontic Health:
Consideration for post or not in endodontically treated teeth.
6 Occlusal Considerations:
Occlusal load and relationship with opposing teeth.
7 Subgingival vs. Supragingival Margins:
Affects both aesthetics and gingival health.
Subgingival margins for aesthetics, manage carefully to avoid periodontal impact.
8 Impression Technique:
Suitability for digital vs. conventional impressions.
9 Patient-Specific Factors:
Oral hygiene, compliance with follow-up care, and patient preferences or expectations.
106
Vital vs. Endodontically Treated Teeth
Vital Teeth retain natural moisture content and structural integrity; dentine supported by hydrated pulp->provides resilience [dentine]
Sensory feedback helps minimize occlusal overload.
Endodontically Treated Teeth:
Loss of pulp and tooth structure weakens the tooth. Dehydration makes dentin brittle, increasing fracture risk.*but Similar resistance to fracture as untreated teeth in lab tests.
Higher risk of fracture due to lack of sensory feedback, inc bite force and additional tooth structure removal for endodontic access.
Decision for Crown Use:
Based on remaining tooth structure and functional load [vertical/lateral forces].
107
Posterior Teeth need crown post RCT?
1 Subjected to vertical and lateral forces.
2 Broad occlusal surfaces and grinding function increase fracture risk.
3 Crowns provide necessary support and protection post-endodontic treatment.
if marginal ridges intact, may not need.
108
Considerations for Crown Placement
1 Aesthetic Considerations
Smile Line:
Color Matching: Match shade and translucency of adjacent teeth.
Ensure color stability over time.
Material Translucency:
Choose materials like lithium disilicate or zirconia based on desired light transmission.
3 Material Selection:
Prefer all-ceramic crowns for superior aesthetics, translucency, and tissue response.
Ensure material strength for occlusal forces (e.g., reinforced ceramics).
4 Occlusal Considerations: MI stable
5 Mechanical Considerations
i Margin Design:
Use subgingival/equigingival margins for a natural appearance and periodontal health.
iiTooth Preparation:
Conservative preparation to preserve tooth structure while achieving retention and resistance (3mm per Goodacre 2001).
iiiFunctional Considerations:
Ensure the crown functions effectively in bite and chewing patterns.
ivPhonetics: Check for proper speech sounds.
v Restorative Space:
Ensure adequate occlusal clearance for chosen material (e.g., zirconia requires less space than PFM).
vi Cementation Protocol:
Use **resin cements (e.g., Calibra)** for superior bond strength and shade range affecting final color.
6 Fabrication Technique:
Utilize CAD/CAM technology for precise fit and aesthetics.
7 Biological Considerations
Periodontal Health:to minimize recession/infl
Biotype and biological width (Gargiulo 1961).
8 Biocompatibility:
Ensure material does not cause adverse reactions, especially for allergies/sensitivities.
9 Maintenance and Durability: ohi
Material should resist wear and staining for longevity.
10 Patient Expectations and cost
109
Modifying an Abutment Tooth for a PFM Crown
1 Auxiliary Grooves or Boxes:
Difficult to ensure alignment with path of withdrawal and avoid undercuts.
Risk of pulp injury.
2Crown Lengthening:
Not in close proximity to pulp; consider if needed for additional retention.
Ortho extrusion as an alternative.
3 Axial Wall Height:
Evaluate if increasing height to at least 4mm is necessary for better retention and resistance.
Ensure existing heights are smooth and even.
4 Margin Designs:
Maintain lingual chamfer at 0.3mm.
Shoulder margin on buccal at 1.5mm width (butt joint or disappearing margin, or metal on lingual).
Rounded internal line angles to minimize stress in zirconia restoration.
Smooth finish lines for optimal seal and fit.
5 Occlusal Reduction:
Ensure 2mm reduction to accommodate restorative material.
May need slight increase for esthetic layering, considering occlusal dynamics.
6 Lingual Chamfer:
Convert to rounded shoulder for uniform margin if using zirconia.
110
When indicating the material and crown design for a 60-year-old patient requiring a full-coverage molar crown, several clinical considerations need to be taken into account:
1 Biological
1 Tooth Structure:
2 Occlusal Forces/ bruxism..
3 Pulpal Vitality/rct- post and core for support; more robust material like metal or zirconia..
4 Periodontal Status:
5 Subgingival Health= biological width
6 Material Biocompatibility:
2 Esthetic Demands: Even though,
esthetics may not be as critical as for anterior teeth, but the crown should still mimic the natural tooth to blend with the rest of the dentition.
3 Mechanical
1 Tooth Preparation: Adequate thickness is necessary to mask the darker color of the metal substructure and to ensure the porcelain veneer duplicates the appearance of a natural tooth in PFM
2 Durability:molar teeth are subjected to higher stress compared to anterior teeth.
3 Opposing Dentition material :zirconia may cause wear on the opposing natural dentition if not adequately polished or adjusted.
4 Patient’s Occlusion: ensuring it harmonizes with the overall occlusal pattern to distribute forces evenly.
5 Marginal Integrity: to prevent microleakage and secondary caries
6 Restorative Margin Placement: Margins in an area accessible for cleaning.
4 Patient's Oral Health: caries, periodontal disease, and any other factors that may impact the success of the crown restoration.
5 Economic Factors: budget= Gold alloys, for instance, are biocompatible and durable but can be more expensive.
6 Material Selection: Consider the advantages and disadvantages of different materials.
7 Longevity and Maintenance: Consider the long-term prognosis of the chosen material. Some materials are easier to repair than others.
8 Technical and Laboratory Support: The dentist's familiarity and comfort with the material, as well as the dental laboratory's expertise in fabricating the chosen type of crown, are also important.
9 Cementation: Different materials require different cementation techniques.
10 Medical History
111
Differences Between Conventional FDP and Resin-Bonded Prosthesis
1 Retention Mechanism +Tooth Preparation::
Conventional FDP: Mechanical retention through extensive abutment tooth preparation.
Resin-Bonded Prosthesis: Micromechanical retention using acid etching and adhesive cement and minimal enamel preparation.
2 Longevity:
Conventional FDP: Longer lifespan.
Resin-Bonded Prosthesis: Limited longevity.
3Indications:
Conventional FDP: Suitable for a wide range of situations, including abutment teeth with restorations.
Resin-Bonded Prosthesis: Preferred for intact abutment teeth. Young growing children
4 Time and Cost:
Resin-Bonded Prosthesis: Quicker and less expensive.
5 Invasiveness:
Conventional FDP: More invasive.
Resin-Bonded Prosthesis: Conservative treatment option.
112
Advantages and Disadvantages
Conventional FDP:
Advantages:
1Greater longevity
2 Higher retention and stability
3 Robust and durable
4 Suitable for multiple missing teeth
5 Abutment alignment mesio-distally with angulation is <25 deg [modify prep]; able accept slight discrepancy unlike RBB must be in same faciolingual plane
6 non surgical option
Disadvantages:
1Extensive tooth preparation
2 Higher cost
3 Risk of pulpal damage
4 Irreversible tooth structure loss
5 hard for OH maintenance
113
Resin-Bonded Prosthesis:
Advantages:
Disadvantages:
1Minimal tooth preparation
2Lower cost
3Conservative approach
4Less chair time
Disadvantages:
1Limited longevity
2Lower retention and stability
3 Suitable for single missing teeth (max 2 lower incisors)
4 Abutment alignment mesio-distally with angulation is <15 deg NOT easy to modify prep dt minimal reduction
5 Not suitable for high occlusal load or deep bite
114
Implant-Supported Prosthesis:
Benefits:
Risks:
1 Preserves adjacent tooth structure-Standalone solution with natural function and aesthetics
2 Maintains alveolar bone
3 Long-term stability and durable
Risks:
1 Invasive procedure with potential complications
2 Higher cost
3 Requires sufficient bone; possible bone grafting
4 Longer treatment duration for osseointegration
115
Removable Partial Denture (RPD):
Benefits:
Risks:
1Least invasive
2 Cost effective
3 Easy to repair or adjust
4 No alteration of adjacent teeth
Risks:
1 Less stable and discomfort
2 Potential for increased plaque accumulation
3 Can cause wear on supporting teeth and tissues
REVISION
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