This document discusses cavity preparation for cast metal restorations. It begins by introducing cast metal restorations and their history. It then defines inlays and onlays. The document discusses various materials used for cast restorations including gold, platinum, and nickel-chromium alloys. It covers the requirements, properties, and classes of different dental casting alloys. The document provides details on cavity preparation principles, outline forms, and features to provide resistance and retention. It also discusses preparation modifications and secondary retention methods.
An inlay may cap none, or may cap all but one cusp.
Sturdevant’s 4th ed. page579
Inlays may be used as single-tooth restorations for proximo-occlusal or gingival lesions with minimal to moderate extensions
Shillingburg page 1
An inlay may be defined as a restoration which has been constructed out of mouth from gold, porcelain, or other material & then cemented into the prepared cavity of a tooth.
William McGehee pg410
a detailed account of the principles of tooth preparation with main reference from Shillingburg
The presentation is available on request. Mail me at apurvathampi@gmail.com
DR. SWARNEET KAKPURE (DEPT OF CONSERVATIVE DENTISTRY AND ENDODONTICS)
THE TOPIC PRESENTED IN SEMINAR COVERS ALMOST ALL THE ASPECTS OF COMPLEX AMALGAM RESTORATIONS INCLUDING PIN RETAINED,SLOT RETAINED AMALGAM RESTORATIONS,CEMENTED,FRICTION LOCKED & SELF THREADING PINS, TMS SYSTEM,AMALGAM FOUNDATIONS ALONG WITH TECHNIQUES OF INSERTION AND MATRIX PLACEMENT.
An inlay may cap none, or may cap all but one cusp.
Sturdevant’s 4th ed. page579
Inlays may be used as single-tooth restorations for proximo-occlusal or gingival lesions with minimal to moderate extensions
Shillingburg page 1
An inlay may be defined as a restoration which has been constructed out of mouth from gold, porcelain, or other material & then cemented into the prepared cavity of a tooth.
William McGehee pg410
a detailed account of the principles of tooth preparation with main reference from Shillingburg
The presentation is available on request. Mail me at apurvathampi@gmail.com
DR. SWARNEET KAKPURE (DEPT OF CONSERVATIVE DENTISTRY AND ENDODONTICS)
THE TOPIC PRESENTED IN SEMINAR COVERS ALMOST ALL THE ASPECTS OF COMPLEX AMALGAM RESTORATIONS INCLUDING PIN RETAINED,SLOT RETAINED AMALGAM RESTORATIONS,CEMENTED,FRICTION LOCKED & SELF THREADING PINS, TMS SYSTEM,AMALGAM FOUNDATIONS ALONG WITH TECHNIQUES OF INSERTION AND MATRIX PLACEMENT.
This presentation specifically deals with the maxillary and mandibular Major connectors used in a cast partial denture. it also mentions the uses, advantages and disadvantages of each,
Bevels and flares are very important components of resin restoration procedure. This presentation focuses on bevels and flares in restorative procedure.
Smear layer is a controversial topic in the field of operative dentistry and endodontics. This presentation includes composition, concepts, structure, advantages, disadvantages, and removal methods of smear layer.
This presentation specifically deals with the maxillary and mandibular Major connectors used in a cast partial denture. it also mentions the uses, advantages and disadvantages of each,
Bevels and flares are very important components of resin restoration procedure. This presentation focuses on bevels and flares in restorative procedure.
Smear layer is a controversial topic in the field of operative dentistry and endodontics. This presentation includes composition, concepts, structure, advantages, disadvantages, and removal methods of smear layer.
The cast metal restoration is versatile and is especially applicable to Class II onlay preparations. The process has many steps, involves many dental materials, and requires meticulous attention to prepration.
Tooth treatment planned to be restored with an intracoronal restoration, but the decay or fracture is so extensive that a direct restoration, such as amalgam or composite, would not be able to sustain or bear forces.
Additionally, when decay or fracture incorporate areas of cusp or remaining tooth structure that undermines perimeter walls of a tooth, an onlay might be indicated.
principles of tooth preparation - ann george final.pptxDrHIMANSHUTIWARI1
No recent literature has reviewed the current scientific knowledge on complete coverage tooth preparations.Nine scientific principles have been developed that ensure mechanical, biologic, and esthetic success for tooth preparation of complete coverage restorations.
preparation for full coverage restorations .pptxSonal Baseer
The preparation of teeth for a full coverage restoration involves reduction of teeth to provide adequate mechanical and aesthetic properties in the restoration.
The prostate is an exocrine gland of the male mammalian reproductive system
It is a walnut-sized gland that forms part of the male reproductive system and is located in front of the rectum and just below the urinary bladder
Function is to store and secrete a clear, slightly alkaline fluid that constitutes 10-30% of the volume of the seminal fluid that along with the spermatozoa, constitutes semen
A healthy human prostate measures (4cm-vertical, by 3cm-horizontal, 2cm ant-post ).
It surrounds the urethra just below the urinary bladder. It has anterior, median, posterior and two lateral lobes
It’s work is regulated by androgens which are responsible for male sex characteristics
Generalised disease of the prostate due to hormonal derangement which leads to non malignant enlargement of the gland (increase in the number of epithelial cells and stromal tissue)to cause compression of the urethra leading to symptoms (LUTS
Title: Sense of Smell
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the primary categories of smells and the concept of odor blindness.
Explain the structure and location of the olfactory membrane and mucosa, including the types and roles of cells involved in olfaction.
Describe the pathway and mechanisms of olfactory signal transmission from the olfactory receptors to the brain.
Illustrate the biochemical cascade triggered by odorant binding to olfactory receptors, including the role of G-proteins and second messengers in generating an action potential.
Identify different types of olfactory disorders such as anosmia, hyposmia, hyperosmia, and dysosmia, including their potential causes.
Key Topics:
Olfactory Genes:
3% of the human genome accounts for olfactory genes.
400 genes for odorant receptors.
Olfactory Membrane:
Located in the superior part of the nasal cavity.
Medially: Folds downward along the superior septum.
Laterally: Folds over the superior turbinate and upper surface of the middle turbinate.
Total surface area: 5-10 square centimeters.
Olfactory Mucosa:
Olfactory Cells: Bipolar nerve cells derived from the CNS (100 million), with 4-25 olfactory cilia per cell.
Sustentacular Cells: Produce mucus and maintain ionic and molecular environment.
Basal Cells: Replace worn-out olfactory cells with an average lifespan of 1-2 months.
Bowman’s Gland: Secretes mucus.
Stimulation of Olfactory Cells:
Odorant dissolves in mucus and attaches to receptors on olfactory cilia.
Involves a cascade effect through G-proteins and second messengers, leading to depolarization and action potential generation in the olfactory nerve.
Quality of a Good Odorant:
Small (3-20 Carbon atoms), volatile, water-soluble, and lipid-soluble.
Facilitated by odorant-binding proteins in mucus.
Membrane Potential and Action Potential:
Resting membrane potential: -55mV.
Action potential frequency in the olfactory nerve increases with odorant strength.
Adaptation Towards the Sense of Smell:
Rapid adaptation within the first second, with further slow adaptation.
Psychological adaptation greater than receptor adaptation, involving feedback inhibition from the central nervous system.
Primary Sensations of Smell:
Camphoraceous, Musky, Floral, Pepperminty, Ethereal, Pungent, Putrid.
Odor Detection Threshold:
Examples: Hydrogen sulfide (0.0005 ppm), Methyl-mercaptan (0.002 ppm).
Some toxic substances are odorless at lethal concentrations.
Characteristics of Smell:
Odor blindness for single substances due to lack of appropriate receptor protein.
Behavioral and emotional influences of smell.
Transmission of Olfactory Signals:
From olfactory cells to glomeruli in the olfactory bulb, involving lateral inhibition.
Primitive, less old, and new olfactory systems with different path
Title: Sense of Taste
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the structure and function of taste buds.
Describe the relationship between the taste threshold and taste index of common substances.
Explain the chemical basis and signal transduction of taste perception for each type of primary taste sensation.
Recognize different abnormalities of taste perception and their causes.
Key Topics:
Significance of Taste Sensation:
Differentiation between pleasant and harmful food
Influence on behavior
Selection of food based on metabolic needs
Receptors of Taste:
Taste buds on the tongue
Influence of sense of smell, texture of food, and pain stimulation (e.g., by pepper)
Primary and Secondary Taste Sensations:
Primary taste sensations: Sweet, Sour, Salty, Bitter, Umami
Chemical basis and signal transduction mechanisms for each taste
Taste Threshold and Index:
Taste threshold values for Sweet (sucrose), Salty (NaCl), Sour (HCl), and Bitter (Quinine)
Taste index relationship: Inversely proportional to taste threshold
Taste Blindness:
Inability to taste certain substances, particularly thiourea compounds
Example: Phenylthiocarbamide
Structure and Function of Taste Buds:
Composition: Epithelial cells, Sustentacular/Supporting cells, Taste cells, Basal cells
Features: Taste pores, Taste hairs/microvilli, and Taste nerve fibers
Location of Taste Buds:
Found in papillae of the tongue (Fungiform, Circumvallate, Foliate)
Also present on the palate, tonsillar pillars, epiglottis, and proximal esophagus
Mechanism of Taste Stimulation:
Interaction of taste substances with receptors on microvilli
Signal transduction pathways for Umami, Sweet, Bitter, Sour, and Salty tastes
Taste Sensitivity and Adaptation:
Decrease in sensitivity with age
Rapid adaptation of taste sensation
Role of Saliva in Taste:
Dissolution of tastants to reach receptors
Washing away the stimulus
Taste Preferences and Aversions:
Mechanisms behind taste preference and aversion
Influence of receptors and neural pathways
Impact of Sensory Nerve Damage:
Degeneration of taste buds if the sensory nerve fiber is cut
Abnormalities of Taste Detection:
Conditions: Ageusia, Hypogeusia, Dysgeusia (parageusia)
Causes: Nerve damage, neurological disorders, infections, poor oral hygiene, adverse drug effects, deficiencies, aging, tobacco use, altered neurotransmitter levels
Neurotransmitters and Taste Threshold:
Effects of serotonin (5-HT) and norepinephrine (NE) on taste sensitivity
Supertasters:
25% of the population with heightened sensitivity to taste, especially bitterness
Increased number of fungiform papillae
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Report Back from SGO 2024: What’s the Latest in Cervical Cancer?bkling
Are you curious about what’s new in cervical cancer research or unsure what the findings mean? Join Dr. Emily Ko, a gynecologic oncologist at Penn Medicine, to learn about the latest updates from the Society of Gynecologic Oncology (SGO) 2024 Annual Meeting on Women’s Cancer. Dr. Ko will discuss what the research presented at the conference means for you and answer your questions about the new developments.
Anti ulcer drugs and their Advance pharmacology ||
Anti-ulcer drugs are medications used to prevent and treat ulcers in the stomach and upper part of the small intestine (duodenal ulcers). These ulcers are often caused by an imbalance between stomach acid and the mucosal lining, which protects the stomach lining.
||Scope: Overview of various classes of anti-ulcer drugs, their mechanisms of action, indications, side effects, and clinical considerations.
Lung Cancer: Artificial Intelligence, Synergetics, Complex System Analysis, S...Oleg Kshivets
RESULTS: Overall life span (LS) was 2252.1±1742.5 days and cumulative 5-year survival (5YS) reached 73.2%, 10 years – 64.8%, 20 years – 42.5%. 513 LCP lived more than 5 years (LS=3124.6±1525.6 days), 148 LCP – more than 10 years (LS=5054.4±1504.1 days).199 LCP died because of LC (LS=562.7±374.5 days). 5YS of LCP after bi/lobectomies was significantly superior in comparison with LCP after pneumonectomies (78.1% vs.63.7%, P=0.00001 by log-rank test). AT significantly improved 5YS (66.3% vs. 34.8%) (P=0.00000 by log-rank test) only for LCP with N1-2. Cox modeling displayed that 5YS of LCP significantly depended on: phase transition (PT) early-invasive LC in terms of synergetics, PT N0—N12, cell ratio factors (ratio between cancer cells- CC and blood cells subpopulations), G1-3, histology, glucose, AT, blood cell circuit, prothrombin index, heparin tolerance, recalcification time (P=0.000-0.038). Neural networks, genetic algorithm selection and bootstrap simulation revealed relationships between 5YS and PT early-invasive LC (rank=1), PT N0—N12 (rank=2), thrombocytes/CC (3), erythrocytes/CC (4), eosinophils/CC (5), healthy cells/CC (6), lymphocytes/CC (7), segmented neutrophils/CC (8), stick neutrophils/CC (9), monocytes/CC (10); leucocytes/CC (11). Correct prediction of 5YS was 100% by neural networks computing (area under ROC curve=1.0; error=0.0).
CONCLUSIONS: 5YS of LCP after radical procedures significantly depended on: 1) PT early-invasive cancer; 2) PT N0--N12; 3) cell ratio factors; 4) blood cell circuit; 5) biochemical factors; 6) hemostasis system; 7) AT; 8) LC characteristics; 9) LC cell dynamics; 10) surgery type: lobectomy/pneumonectomy; 11) anthropometric data. Optimal diagnosis and treatment strategies for LC are: 1) screening and early detection of LC; 2) availability of experienced thoracic surgeons because of complexity of radical procedures; 3) aggressive en block surgery and adequate lymph node dissection for completeness; 4) precise prediction; 5) adjuvant chemoimmunoradiotherapy for LCP with unfavorable prognosis.
Pulmonary Thromboembolism - etilogy, types, medical- Surgical and nursing man...VarunMahajani
Disruption of blood supply to lung alveoli due to blockage of one or more pulmonary blood vessels is called as Pulmonary thromboembolism. In this presentation we will discuss its causes, types and its management in depth.
2. Introduction
• The cast metal restorations are versatile and procedure requires
meticulous care in preparation and laboratory procedures.
• Dr. Phil Brook in 1897, was the first to introduce Inlay in
dentistry who gave the concept of forming an investment
around a wax pattern, eliminating the wax and filling the
created mold with a gold alloy.
• In 1907 Taggart changed the practice of restorative dentistry by
introducing his technique of cast gold dental restorations.
• It was most certainly Taggart who recognised the significance of
cast gold restorations.
3. Definitions
Inlay
- It is primarily intracoronal cast
restoration that is fabricated outside
the oral cavity and placed in
prepared cavity.
Onlay
- An onlay is combination of
intracoronal and extracoronal
restoration when one or more cusps
are covered.
4. Materials For Cast Restoration
• Until recently gold based alloys were the only choice for cast
dental restorations. The ADA specification #25 still requires
75% of gold – plus – platinum group metals to be present in the
alloys for cast restoration.
• According to sturdevant,
Traditional high gold alloys
Low gold alloys
Platinum-silver alloys
Base metal alloys
5. According to Marzouk,
• Class 1 – gold and platinum based alloys
• Class 2 – low gold alloys. Gold < 50%
• Class 3 – non – gold platinum based alloys
• Class 4 – nickel – chromium based alloys
• Class 5 – castable , moldable ceramics
6. Requirements of dental casting alloy
• Biocompatability
• Coefficient of thermal expansion
• Melting range
• Tarnish and corrosion resistance
• Modulus of elasticity
• Castability
• Finishing and polishing
• Esthetics and cost factor
7. Gold alloys – class 1
• According to ADA #25,
• - type 1 (83% Au, 10% Ag, 6% Cu) – soft gold alloys – for
restorations subjecting to slight stress like inlay
• - type 2 (77% Au, 14% Ag, 7% Cu) – medium hard alloys – for
restorations with moderate stress like onlay.
• - type 3 (75% Au, 11% Ag, 9% Cu) – hard alloys – high stress
situations like onlay, short span FPD, veneer crowns.
• - type 4 (69% Au, 25% Ag, 10% Cu) – extra hard alloys – high
stress situations like long span FPD, crowns, endodontic post and
core.
8. Low gold alloys – class 2
• Economy gold alloys
• Gold content lower than class 1 alloys
• Palladium replaces gold.
• Palladium is responsible for imparting the desirable physical
properties, strength, hardness ant the plasticity of the mass.
9. Non – gold platinum based alloys – class 3
• Composed mainly of palladium and silver.
• They are either palladium – silver alloys or silver – palladium
alloys.
• Palladium is most influential in dictating the properties.
• Also has indium, copper, tin, zinc constituting not more than
10%.
• Indium acts as a scavenger while melting, and increases
resistance to tarnish and corrosion.
10. Nickel – chromium based alloys – class 4
• These metals are referred to as non-noble or non-precious alloys
because of their low cost.
• The chromium content in these alloys should not exceed 30%.
• The chromium imparts the passivating effect on base metals
making them corrosion resistant.
• Beryllium and molybdenum have been added to improve upon
properties of the base metals.
• Beryllium – control castability and oxidation
• Molybdenum – decreases co-efficient of thermal expansion.
11. Castable moldable ceramics – class 5
• Composed of aluminium tri oxide( at least 50%) and
magnesium oxide ( at least 15%)
• Ratio of Al2O3 : MgO is 7:1
• To this 0.5% of stearate or wax is added to improve the
moldability.
• When heated above the glass transition temperature ( 30-150°)
the mass becomes moldable and deformable.
12. Physical and mechanical properties
Type of
cast
metal
Density
gm/cm²
Melting
range °F
Tensile
strength
PSI
Yield
strength
0.2%
PSI
Elongati
on
M.E.
PSI
Hardnes
s VHN
Tarnish
and
corrosio
n rate
Class 1 15 – 16 1800-
2000
80,000 40,000 20-25% 10-12
million
150-170 Almost
0%
Class 2 11 – 12 2200 100,000 47,000 20% 12
million
200 2-3%
Class 3 10-11 2250 140,000 65,000 15 –
18%
15
million
250 5 – 10%
Class 4 8 3500 160,000 80,000 3-11 % 30
million
315 0%
Class 5 2.7 3300 19,000 - 0% 60
million
350 0%
13. Indications
• Large restorations
• Endodontically treated teeth
• Teeth at risk of fracture
• Dental rehabilitation with cast metal alloy
• Diastema closure and occlusal plane correction.
• Prosthodontic abutment.
• Correction of occlusion.
• Wide open contacts.
• Sub – gingival lesion.
14. Contraindications
• Physiologically young dentition with large pulp chamber.
• Developing and deciduous tooth.
• High plaque / caries index
• Dissimilar metals.
• Esthetics.
• Small restoration.
16. Dis-advantage
• Extensive tooth preparation
• Cemented restoration, discrepancy and microleakage
• Abarassive and splitting force on natural tooth
• Galvanic currents.
• Number of appointments and chair side time.
• Cost and temporary restoration requirement.
• Technique sensitive.
17. Factors affecting the design of the cavity
• Length of clinical crown.
• Anatomic contours of the occlusal, proximal, buccal and lingual
surface.
• The position of tooth in arch.
• The occlusal and proximal relations.
• Unusual esthetic conditions, if any.
• The condition of soft tissues around the tooth.
• The extend and location of carious lesion.
18. Mouth preparation prior to cast restoration
For a single tooth cast restoration, every precaution should be
taken to ensure that the longevity of the restoration.
• Control of plaque.
• Control of caries.
• Control of periodontal problems.
• Proper foundation.
• Control of pulpal condition of tooth.
• Occlusal equilibrium.
• Diagnostic wax-ups and temporary restoration.
• marzouk
19. Burs used in cavity preparation
• Bur no:271 – tungsten carbide
tapering fissure bur with 0.8mm
width.
• Bur no:169L – tapering fissure
with 0.5mm width.
• Bur no:8862 – flame shaped
diamond instrument.
20. Principles of cavity preparation for cast
restorations
• Cast alloys can be used to restore intra-coronal or extra-coronal
restorations.
• Most single tooth restorations are a combination of these intra
and extra coronal restorations.
• Intracoronal restorations are mortise shaped, having definite
walls and floors joined by line angles and point angles.
• General principles of tooth preparation can be applied to
intracoronal preparation with slight modifications for the
effectiveness of the preparation.
21. Outline form
External outline form
• External outline form should consist of straight lines and
smooth following curves, avoiding any short angles.
• Cavosurface margin placed is placed on sound, unbroken tooth
tissue to obtain a well fitting casting.
• Placement of bevels make the outline form slightly wider.
22. Internal outline form:
• The pulpal floor and the axial wall of the inlay preparation
should be placed in the dentin and care should be taken to
protect the pulp.
• Line angles in both occlusal and proximal portions of the
preparations should be well defined and the axio-pulpal line
angle slightly rounded.
• It is sometimes desirable to incline the cutting instrument so that
it forms either an exaggerated taper from the cavosurface to
pulpal floor or a long bevel on that area.
23. Outline form
• Depth of the cavity is 1.75 to 2
mm from the central groove.
• Long axis of 271 bur is held
parallel to long axis of tooth
crown at all times.
• For mandibular molars and
premolars the bur is tilted 5-10°
lingually to conserve the
strength of lingual cusp.
• After occlusal outline
preparation, the cavity is
extended proximally as in
Black’s class 2 preparation.
24. Outline form
• Proximal ditch cut is made.
• 0.3 mm of enamel and 0.5 mm of dentin is cut since the width
of the bur is 0.8 mm.
• Gingival seat is kept just below the contact area.
• In ideal box , the buccal and lingual walls should be
perpendicular to proximal surface clearing adjacent tooth by
0.5mm.
• Depth is 0.2 – 0.5 mm in the dentin.
25. Outline form
• Ragged enamel edges at the gingival and proximal areas may be
removed using hand instrument such as chisel or flame shame
shaped diamond point.
• However it is better to postpone the finishing till the remaining
caries and/or old restorative material is completely removed and
the base is applied.
• Width of the cavity – 1/3rd of the cuspal inclines is included on
both sides of the central groove.
• In madibular premolar, 2/3rd of occlusal width is placed on the
buccal inclined plane and 1/3rd from lingual incline plane.
27. Preparation path
• Single insertion path
• Opposite to occlusal loading force.
• Parallel to long axis of the tooth.
• Helps in retention and decrease its micromovements during
function.
• The occlusal force should seat the restoration rather than
displace it.
28. ResistanceAnd Retention Form
• Parallel opposing walls aids in retention.
• Flat pulpal and cervical floors – resistance form.
• Well defined angles help in maintaining precise relationship
between restoration and tooth tissue improving retention and
resistance.
• Divergent walls – 2-6° taper increased in case of deeper cavity
but not exceeding 10°.
29. Factors affecting proximal margins
• The extend of tooth tissue loss
• The location of that loss.
• Configuration of tooth i.e curvatures and embarasures.
• The relationship with adjacent teeth.
• The need for extra retentive devices.
30. Pulpal floor
• The pulpal floor should be flat.
• It should be 1 – 1.5 mm from DEJ.
• The pulpal floor should meet all the surrounding walls at
definite line angles except for the axiopulpal line angle where it
should be rounded.
31. Features for resistance and retention
• Axiopulpal line angle rounded to dissipate stress equally.
• Occlusal dovetail or interlock prevents proximal displacement
of restoration.
• If no proper parallelism or no proper depth of cavity is there
then secondary retentive devices like slots and pinholes can be
given.
• Shallow retentive grooves , 0.3mm deep, maybe given on
buccoaxial and linguoaxial line angles. – indicated when
preparation is shallow.
34. Preparation Features For Circumferential Tie
• The weakest link in any cast restoration is the teeth/cement/cast
joint.
• The peripheral marginal anatomy is called circumferential tie.
• Bevel – plane of the cavity wall or floor directed away from
the cavity preparation.
• Bevel helps in
• - lap sliding fit at the gingival margin
• - results in 30° metal that is burnishable.
• - Weak enamel is removed.
• Bevels should include surface defects and supplementary
grooves.
35. Types of Bevels
1. Partial bevel – not more than 2/3rd of
enamel. Enameloplasty.
2. Short bevel – entire enamel without dentin.
For gold alloys.
3. Long bevel – entire enamel and one half of
dentinal wall. Intracoronal cast restorations.
4. Full bevel – whole of enamel and dentin.
Not used due to lack of retention.
5. Reverse bevel – for cusp capping. Usually
on facial and lingual surface of cusp.
6. Hollow ground bevel – in the form of
concavity. For materials with low
castability. Not used.
36. Preparation of bevels and flares
• The slender flame shaped fine-grit diamond is used to bevel the
occlusal and gingival margins and to apply the secondary flare
on the facial and lingual walls.
• This result in 30-40° marginal metal and 140-150° cavosurface
margin.
37. TypesAnd Features Of FacialAnd Lingual
Flares
• Flares are present on the proximal box of intra-coronal cast
preparations.
Two types of flares:
1. Primary flare – similar to long bevel formed on the facial
and lingual wall of proximal box. It has angulation of 45° to
the inner dentinal wall proper.
Funtions : makes the proximal portion of the restoration self
cleansable.
1. Secondary flare – it is a flat plane superimposed peripherally
to a primary flare. Indicated in lesions with wide contact areas
and wide bucco-lingual extensions.
41. Box preparation
Introduced by Dr.G.V.Black
Proximal cavities are box shaped.
Advantages are
• Resistence and retention form
• The outline form can be made on all types of teeth.
• Minimum display of metal.
Disadvantages are
• Involves removal of lot of tooth structure.
• Time consuming clinically.
• Narrow bevels leave a sharp edge and an undercut gingivally, which cannot
be reproduced satisfactorily.
• While taking impressions, distortions and breaking of wax pattern occurs
43. Slice preparations
• This form of cavity is modified so that the proximal surface is
flat without definite side walls.
• Retention mainly depends upon occlusal key, locks cut in the
axial wall.
Indications
• As abutment in bridge work.
• Teeth with proximal undercuts can be eliminated which
facilitates taking impression.
• For indirect wax pattern technique.
44. Slice preparations
Advantages :
• Less tooth structure is sacrificed.
• Quicker and easier.
• Well protected enamel margins.
• Increase resistence and retention by exposing larger amount of
tooth structure.
Disadvantages :
• It displays more amount of gold. (Thoma 1951)
• Direct wax pattern cannot be made as distinguishing between
margins become difficult.
• Metal margins are likely to distort due to less thickness.
45. Slice preparations
It involves conservative disking of
proximal surface to establish buccal
and lingual extend of finish lines and
provide a lap joint.
46. Auxiliary slice preparations
• Wraps partially around the proximal line angles, thus providing
additional support.
• Resistance form is enhanced
• Provide external retention form.
47. Modified flare preparation
• Modified flare is a combination of box preparation and slice
preparation.
• Minimum disking of proximal walls is done for better finishing
and polishing.
48. Secondary modes of retention
Luting cement
• Fills gaps between the inlay and the tooth giving a physio
chemical bonding.
• Physical – zinc phosphate
• Chemical – glass ionomer cement
• The exposed cement dissolves in oral cavity . So it should not
be considered as a retentive factor
49. grooves
• The grooves are placed in the bucco-axial and linguo-axial line
angles with 169L bur.
• It is placed at the expense of buccal and lingual walls and never
at the expense of axial wall.
• Its depth is 0.3mm.
50. Reverse bevel
• It is given on the gingival seat. This
bevel has three planes.
• First – reverse bevel plane where
the inclination is on the
gingivoaxial plane which prevents
proximal displacement of the
restoration.
• Second – flat plane made of dentin.
• Third – plane that is sloping away
from the axial wall made up of
enamel and dentin. This helps in
preventing proximal displacement
51. Internal box
• It is made on the pulpal floor,
which improves retention by 4-5
times.
• It should have sharp line and point
angles and definite walls.
• This prevents micro movements of
the inlay.
• Internal box should always be
reciprocated with reverse bevel or
groove .
52. Roughening of the pulpal floor
• Pulpal floor is made more
retentive by irregularities and
lateral locking.
• The irregularities should not
have undermined enamel.
53. Precementation grooves.
• After casting, making grooves on the walls of inlay and/or on
the cavity wall exactly opposite .
• This will house a solid mass of the cement and help in good
retention.
Electrolytic etching of inlay.
• This gives hinge like projections
• Procedure – the proximal and occlusal surface is protected with
wax and kept in electrolyte solution of 0.5 normal nitric acid.
• Inlay is kept in anode and metal with greater EMF in cathode
• Current causes microporosities in inlay surface that enables the
luting cement to flow into it for better retention
• This takes 10-15 min
54. Tooth preparations for onlay cast
restorations
It is partly intracoronal restoration and partly extracoronal
restoration, which has cuspal protection as main feature.
Indications
• Cuspal protection is considered when the lesion width is 1/3rd to ½ the
intercuspal width.
• Cuspal protection is mandated when the length:width ratio is more than
2:1 .
• When there is a need to change the dimention, shape and inter relationship
of the occluding surfaces, onlay cavity is considered as it is more
conservative.
• Ideal for abutment teeth for RPD or FPD.
• When inclusion of wear facets that exceed the cusp tips and triangular
ridges are necessary, onlay is considered.
55. General shape
• Onalys are dovetailed internally and follow the cuspal anatomy
externally.
• Proximal box are cone shaped.
• The main feature of the design is capping of functional cusp and
shoeing of non functional cusps.
56. Tooth preparation for onlay
Occlusal preparation
• The initial entry is made in the
central fossa to a depth of 1mm
into dentin( 2.5mm in total
depth).
• The occlusal outline form must
be as conservative as possible.
• The bur is kept in long axis of
the tooth so that a taper of 3-5
deg divergence is provided to
the internal walls.
57. Proximal preparation
• The boxes are created on the
proximal surface.
• The facial and lingual walls should
exhibit a combined divergence of 6
to 10 deg from each other as was
provided in the occlussal area of
the preparation
58. • The facio-lingual dimension is
likely to be determined by the
presence of restoration, caries
lesion.
• The bevels will extend the
preparation slightly beyond the
proximal contact area so that the
margins of the restoration will be
accesible for finishing with a disk.
59. Cuspal reduction
• A carbide bur or a diamond bur is used to reduce the cusps.
• Depth cuts of 1.5-2mm are made for the centric cusps and 1mm
for non centric cusps.
• After depth cuts are made, a uniform reduction of cusp that
parallels the anatomic contours of the occlusal surface is made.
60. Shoulder preparation
• A shoulder is prepared on the external surface of the centric
cusp to provide a band of metal to protect the tooth.
• The bur is held parallel to the external surface of the tooth and
a shoulder about 1mm in height and 1mm axial depth is cut.
• The finish line should extend at least 1mm beyond occlusal
contact.
• The occluso-axial line angles are rounded.
• Adequate clearance of 1-1.5mm in all eccentric mandibular
positions.
61. Non – centric cusp
• A chamfer or long bevel is given on non-centric cusp.
• A barrel shaped bur can be used to create chamfer.
• The bur is positioned at 45 deg to the axial surface.
• This provides additional cusp protection.
62. Gingival bevel
• A smooth distinct bevel on the gingival margin is established
with no:7901 bur or GMT.
• The bevel should be 0.5mm width and at 45 deg to the external
root surface.
63. Shoulder bevel:
• A 1mm bevel is placed on the shoulder with no:7901 bur.
• This bevel is blend with the proximal bevels.
• Any sharp angles at the junction of various bevels and across
the occluso-axial line angles are eliminated.
Proximal bevels:
• The proximal bevel or flare is established with a fine tapered
diamond.
• Divergence established from gingival floor occlusally.
• The proximal bevel should blend smoothly with the gingival
beval, lingual and buccal bevels.
64. Retention grooves
• Retention grooves are placed in the proximal boxes.
• The grooves should be present bisecting the facio-axial line
angle and the linguo-axial line angle.
• The grooves should diverge occlusally.