Final Revision Flashcards
Do we prefer restorative material core with or without a post?
without a post b/c no further structure is removed
For which teeth does the restorative material core without a post, works best and why?
best for molars b/c of large pulp chamber space where core material will be placed
but for premolars and anteriors as well
Core retention can be obtained using:
undercuts slots grooves boxes pulp chamber !! root canals !! pins bonding
Core definition:
= center/base of a structure
- restores sufficient coronal anatomy of a vital or endo treated tooth
When is the choice of core not important?
where there is substantial residual coronal dentin
SOS
When we should use a post? (indications)
- if only 1 cavity wall is remaining./less than 2 axial cavity walls or if there are no cavity walls
- if teeth are used as RPD abutments
- a wall less than 2 mm thickness (not consider as wall)- 1 mm
- when the residual tooth structure is not enough to retain the core/ to retain a core in a tooth with extensive loss of coronal tooth structure !!!! it should be used only if there are no other options to retain a core
- if high tooth length over bone crest
- if less than half of the residual tooth
- for retention of core
- Premolars: small pulp chamber so require more often a post than molars
- Molars: post placed in largest and straightest canal, not used that often
- Anteriors: when there is thin remaining tooth structure after RCT and crown prep, they have small pulp chambers so need posts (not enough R and retention)
- lateral forces and teeth positions are another reason to know when a post is needed
- determined by the remaining coronal tooth structure and the functional tooth requirements
- posts do not make the roots/teeth stronger !!!!!!!
When you should consider a core ‘a build up’?
when it contributes to the strength and retention of a crown preparation
When you should consider a core ‘a filler’?
when it alters the shape of the prep in order to eliminate undercuts
Characteristics of the ideal core material:
stable in wet env easily manipulated rapid, hard set for immediate crown prep high compressive and tensile strength high modulus of elasticity (rigid) high fracture toughness inert (no corrosion) cariostatic properties (inhibit the formation of dental caries) biocompatible cheap
Core material examples:
composite resin, amg, resin-modified glass ionomer, glass ionomer
ADV Vs DISADV of Composite Resin:
ADV:
strong, used in thinner sections than AMG, fast-setting, doesn’t contain mercury, aesthetic, doesn’t always need matrix placement, can bond to most of the current post systems, can be dual-cured or self-cured, better bonding if resin luting cements are used, different delivery systems, different consistencies, can be used as a luting cement and core material at the SAME TIME, can be bonded
DISADV:
high technique sensitivity (shrinks), difficult isolation for deep cavities, same color with tooth and core so difficult to distinguish between them, incompatible with ZOE sealer, many adhesive systems incompatible with dual or self cured composites, relies on multi-stage dentin bonding requiring effective isolation
ADV Vs DISADV of Amalgam:
ADV:
not technique sensitive, strong, good sealing (no shrinkage), CAN BE BONDED, contrast with tooth (can distinguish them)
DISADV:
best to set 24h before tooth prep, weak in thin section, not aesthetic, contains mercury
Recommendations of Composite Resin Vs Amalgam:
Composite Resin:
for all teeth, for interim restoration (provisional use) - takes longer than amg, material of choice, post cementing, core build up, cementing of restoration
Amalgam:
for posteriors, for interim restoration (provisional use), for pin retention (avoid it), for long term use, core build up
Resin-modified glass ionomer ADV Vs DISADV:
ADV:
bonds with tooth, stronger than GIC, light cured - adv when you use it as a base (not for metal restorations), FLUORIDE RELEASE, biocompatible, replaces many GICs today
DISADV:
weaker than AMG and composite, ABSORBS WATER and swells leading to porcelain crack
Recommendations for Resin-modified glass ionomer Vs Glass ionomer
filler Vs build up core?
useful FILLERS but not as core build up materials
Glass ionomer ADV Vs DISADV:
ADV:
bonds with tooth, FLUORIDE RELEASE
DISADV:
weak material, tends to crack, radiolucent, little improvement in physical properties
Nayyar core:
for posterior teeth and badly broken down teeth needs 2-4 mm coronal GP removal used with cuspal coverage condensation of AMG into canal orifices alternative to post
Endocrown:
ceramic restoration and then bond it not for long term high technique sensitive no need for post and core keep enamel in order to bond alternative to post
Types of post:
active/passive, parallel/tapered, prefabricated/custom-made, metal/fiber/zirconium
SOS
Ideal post properties:
biocompatible, cheap, radiopaque, aesthetic, similar mechanical properties to dentin, retrievable, resistant to fracture, not technique sensitive, min prep required for post space
SOS
Active Vs Passive posts:
Active:
= engages with the root dentin via threads and gain retention from this (act like screws)
-more retentive than passive posts (most retentive system we have)
-no longer recommended b/c they cause high stresses into the root and microcracks leading to root fracture!!
-should be used to short roots
Passive:
= sits in the prepared canal space without engaging with the dentin
-for retention
-retained by luting agent
-more favorable stress distribution when post is situated passively !!!!
SOS
Parallel Vs Tapered posts:
Parallel:
- more retentive
- induce less stress to the root due to less wedging effect so less risk of root fracture
- require more dentin removal so higher risk of perforation
Tapered:
-for thin roots and delicate morphology teeth !!!!!!!!
-most systems combine both of them together
SOS
Custom-made posts DISADV Vs ADV Pre-fabricated posts:
Custom-made posts: (cast)
-more conservative most of the times
DISADV
-requires 2 appointments (temporization and laboratory fees)
-temporary crowns/posts are ineffective in preventing contamination of the RC b/w visits
-expensive
-leak a lot
-higher chance of mistakes since more appointments
Pre-fabricated posts: ADV -1 appointment -cheaper -easier -many different sizes and materials available -used to avoid core decementation
SOS
Custom-made posts/cores indications:
- when multiple teeth require posts
- when tooth is misaligned (achieves proper alignment with adjacent teeth)
- for tapered roots and roots with substantial concavities (mandibular I and maxillary P1)
- oval shape RC (pre-fabricated are for round shapes)
SOS
Metal posts:
- made of stainless steel, NiCr, Ti alloys
- very rigid and strong (to transfer all forces to the RC)
- better retention of cement and core material
- provide channels for cement to escape during cementation
- Ti posts are less prone to corrosion but they are hard to detect on radiographs due to similar radiodensity to GP
- if they deform, they cause stress and then can cause root fracture
SOS
Fiber posts:
-we always use resin cements to place these posts
2 types:
1. Carbon fiber posts:
ADV:
-similar modulus of elasticity with dentin so forces are distributed more evenly in the root, reducing the risk of root fractures SAME
DISADV:
-dark, non-aesthetic OPPOSITE, hard to mask and unsuitable for use under ceramic restorations
2. Glass fiber posts: ADV: -similar modulus of elasticity with dentin so forces are distributed more evenly in the root, reducing the risk of root fractures SAME -aesthetic OPPOSITE -allows bonding to post to resin cement -easy to retrieve by drilling DISADV: -TECHNIQUE SENSITIVE -debonding is complicated -because the modulus of elasticity and flexural strength are similar to that of dentine, occlusal load may result in flexure, micro-movement and subsequently leakage, secondary caries and loss of the restoration (this risk is reduced if sufficient ferrule present)
SOS
Zirconium posts:
ADV:
aesthetic
high strength to bending forces
DISADV:
- rigid and hard -> may cause root fractures
- doesn’t bond well with core material
- not recommended for posteriors b/c of higher occlusal forces !!!
- retrieval of fractured zirconium post is difficult
Mr Plingos never used them
SOS
Principles of posts:
length (where retention comes from)
apical seal
diameter
SOS
Post Apical seal:
- determines length
- if post too long for retention then you will lose apical seal
- no leakage at 4 mm of apical seal
- more leakage and post-treatment periapical lesions when less than 3 mm of GP was left
- leave 4-5 mm space at least, for GP
best: 5 mm
worst: 4 mm (NOT 3 mm)
SOS
Post Length:
- where retention comes from
- ideal post length: 2/3 the length of the root OR at least equal to the clinical crown of the tooth; OR at least half the length of root in bone
- length and shape of root determines the length of the post
- length of the post should not compromise the minimum adequate apical seal
- the greater the length the better the retention and better stress/force of distribution (if post too long for retention then you will lose apical seal)
- when root short or curved not able to use long post
- molars with short roots more than one post with shorter length will provide additional retention
- shorter posts may increase the possibility of root fractures due to stress concentration on the gingival margin
-rely more on the post length than the cementation, since the bonding inside the canal is not predictable
4-5 mm rule for apical GP works for:
for all teeth except Molars
Molar posts should not extend more than 7 mm apical to the canal orifice at the base of the pulp chamber, therefore this rule is not for molars
SOS
Posts should:
be as long as possible
extend to GP w/o voids
-bearing in mind the root length and root morphology - root concavities and curvatures (limitations) and without compromising the apical seal of GP !!!!!!
SOS
Post Diameter:
- shouldn’t exceed 1/3 of root diameter !!!!
- as diameter increases, stress in the root increases and fracture resistance decreases due to unnecessary removal of dentin and root weakening (so the larger diameter the more removal of dentin; and we don’t want thin walls)
- post tip diameter shouldn’t exceed 1 mm (not for any tooth; it depends)
The thicker the post:
the less flexible, the more inside the forces are transmitted
SOS
Post complications:
core decementation vertical root fracture post fracture post/core decementation root perforation root concavities
SOS
Core decementation:
= not correctly bonded to rest of the structure and it came off
solution: longer post for better retention, pre fabricated b/c cements break easily
SOS
Vertical root fracture:
thick and very long/large post
SOS
Post fracture:
very thin post and probably not good ferral effect so forces are transmitted to post and loss of proprioreception and also a different material was used than what was necessary
SOS
Post/core decementation:
not good/lack of ferral effect and cementation procedure went wrong so the post didn’t fit the space correctly
SOS
Why did root perforations happen?
not following the RC anatomy and going straight to the bifurcation area
-the worst you can make to a tooth
Root concavities: Which roots to avoid?
mesial roots of lower M and buccal roots of upper M
b/c their root surfaces facing the furcation are common sites for perforations
SOS
How to prepare space for post?
by removal of GP by thermal, mechanical or use of solvents
then prepare the dentinal walls
What is the first step of RCT?
final coronal restoration to prevent re-infection
prevent bacteria from re-entering the RC
Which technique for the removal of GP is the best and why?
thermal removal b/c it removes only GP, NOT dentin
SOS
Thermal removal of GP process:
- heated instrument with desired length is inserted into GP to soften it and remove it
- radiograph used for correct dimension measurement and a rubber stop to mark the length
- heat plugger used for vertical compaction of the softened GP
SOS
Mechanical removal of GP adv and disadv:
process:
- efficient and most common method
- can result in the most damage to the tooth -> root weakening, periodontium damage, root perforation
process:
- use of non-end cutting drill to remove GP
- smallest size of drill GG used first to reduce the risk of overheating and the risk of cutting away root dentin to one side of the canal
SOS
GG drill sizes Vs Peeso Reamer sizes Vs Tungsten Carbide round bur sizes:
GG drill sizes:
2,3,4
-their edge doesn’t cut, only cut the at the sides
Reamer sizes:
4,5,6
Tungsten Carbide round bur sizes:
not FG 4-8
SOS
Use of solvents for removal of GP:
- to soften the GP use of Eucalyptus oil, oil of turpentine and chloroform(-> toxic and carcinogenic)
- DISADV: difficult to control the depth of GP softening and risk of potential leakage to the periradicular tissues
- used to repeat a RCT, not for RC preparation
- avoided
Why do we need clean (not disinfected, but clean) walls?
B/c we want to bond
-if there’s even a little saliva or blood it wont bond well
The post drill should only be used:
- to REMOVE any minor amounts of DENTIN which prevent the complete seating of an appropriately selected diameter of post
- WITHOUT heavy apical or lateral FORCES
- should NOT be used to remove GP
- included with prefabricated post kits
- should not change anatomy of the canal
When are Endo files used in canal prep?
after GP removal to ensure a round prep
The post should provide adequate retention of the core and crown primarily … and secondarily by …?
primarily: through its adequate length
secondarily by: the use of adhesive techniques
SOS
What are the types of cements we have?
conventional or adhesive cements
temporary or definitive cements
Which are adhesive cements?
light cure resin dual cure resin self cure resin self etch resin => cements
Which are conventional cements?
zinc phosphate zinc polycarboxylate GIC resin-modified glass ionomer ZOE (temporary) => cements
SOS
temporary Vs definitive cements:
temporary cements =allows restoration to be removed after assessment of its performance
definitive cements =restoration must be destroyed to be removed (permanently on the tooth)
What are the cautions that we need to take into account when using temporary cements?
- restoration not easily removed
- restoration may DISLODGE
- pt may not return for permanent cementation
- to avoid with single unit restorations the risk of ingestion or inhalation
SOS
How to choose a cement?
it depends on 2 things:
- requirements of the MATERIAL
- retentiveness of the prep and restoration (TOOTH)
DO NOT USE A STRONGER CEMENT IF YOU DO NOT NEED TO
Conventional cements Vs Adhesive cements Indications:
Conventional cements = retained in tooth by friction (adhesive, by bonding)
- retentive conventional castings: ex: pfm, bridges, metal inlays/onlays
- metal pre-fabricated or cast posts
- retentive tooth colored restorations
Adhesive cements:
- all ceramic restorations requiring adhesive bonding
ex: feldspathic, porcelain veneers, inlays/onlays - non-retentive conventional castings ex: pfm
- resin bonded bridges ex: maryland
- posts of any type (better to avoid doing the conventional way with posts)
- non-retentive natural tooth colored restorations
ex: zirconium oxide or lithium disilicate crowns - > all these you can cement, you can bond
for non-retentive preps you go for the strongest cement, so conventional resin cements
SOS
Characteristic of conventional cements Vs adhesive cements:
conventional cements:
- ionic
- susceptible to acid attack
- more soluble in oral environment so can get easier carries
- less mechanical properties
- when proper isolation can’t be achieved, these are recommended
adhesive cements:
- more technique sensitive
- more difficult to use
- more difficult to clean up (tooth colored so difficult to see)
- more expensive
- more difficult to remove
- more time consuming
- need good isolation
- MORE MECHANICAL PROPERTIES since resins have more fillers so they are stronger
- bonding so better retention
- increase the R of post and tooth from fracture
- LESS SOLUBLE IN ORAL CAVITY
Cementation process:
hydrofluoric acid then silane primer then on bonding cement
SOS
Zinc Phosphate cement:
-conventional cement
-low film thickness (25μm) !!!!!!!!!!
-easy clean up of excess cement
-good working time that can easily manipulated
-safe to use, it won’t kill the pulp (only bacteria kill the pulp)
-acidic cement (less than phosphoric acid)
-not toxic
-a little pulp irritation on placement but it is reversible
-used for inlays/onlays, crowns and bridges
• Very long successful track record
SOS
Zinc Polycarboxylate cement:
- conventional cement
- weaker cement
- more biocompatible
- low working time
- more difficult to clean up than ZnPO3
- less irritating to the pulp
- thicker consistency during mixing
- more difficult to use than ZnPO3
- used for metal restorations, covers the pfm, for retentive restorations of crowns and bridges (not for single crowns or less retentive preps, not on an old ceramic restoration or transparent restorative)
What is the result if the cement’s thickness is high?
/What is the result if the cement starts setting quickly?
restoration won’t sit properly
Glass Ionomer Cement (GIC) :
- conventional cement
- biocompatible
- chemical bonding to dentin
- hydrophilic (adaptation to dentin)
- fluoride release (need of F in mouth to take it and then release it)
- stronger than ZnPO3 and Zn polycarboxylate
- should be protected from water for at least 10 min
- no indication that is improving caries resistance
- more soluble and weaker than RMGI cement
(indicated for: luting, base, fissure sealing, restorative fillings prior to crown prep and fillings)
Resin cements:
= composite resins
- bonding to tooth same as restorative composite resins
- different polymerization
- low viscosity
- more technique sensitive
- more difficult to use
- more difficult to clean up (tooth colored so difficult to see)
- more expensive
- more difficult to remove
- more time consuming
- need good isolation
- more flowable than most cements
- dual, self and light cure-> ONLY FOR THIN PORCELAIN VENEERS
- require a bonding agent (any)
Adhesive cements Vs Resin cements:
same properties except:
- mode of polymerization
- viscosity
SOS
What are the 5 classes of adhesion?
ETCH AND RINSE:
• 3 step: acid etching, primer and bonding resin (separate and individual solutions)
-BETTER -> for direct restorations
-DUAL CURE (ADV)
-The 1st hydrophilic dentin bonding agents
-compatible to dentin
-process:
1. phosphoric acid (rinse it off)
2. then apply hydrophilic primer
3. filled/unfilled resin bonding agent containing both hydrophobic and hydrophilic monomers
• 2 step: acid etching and primer with bonding resin in a single bottle
-completely etching enamel and dentin with phosphoric acid
SELF ETCH: •2 step: 2 bottles: Self Priming Etchant /Self Etching Primer and Bonding Resin -primer and acid etch in 1 bottle, and bonding resin -DUAL CURE activator (ADV) -best for indirect restorations or posts -can use selective etch -ex: MILD ETCHING (not complete etch) -best out of all self etch systems
•1 step: all in 1 bottle (UNIVERSAL - primer, acid etch and bonding resin)
- easier for the dentist to use
- total etch using a phosphoric acid and then apply the universal adhesive OR selective etch step
- you might also not use phosphoric acid at all
- used for indirect restorations or direct restorations
•1 step: mixing 2 or 3 components only prior to the clinical application
SOS
Why is 3 step etch and rinse adhesive better than 2 step etch and rinse adhesive?
- it results in better laboratory and clinical performance
- with 2 step you put hydrophilics in the same bottle with hydrophobics which is not good; they are not compatible with each other
DISADV: more difficult to use, expensive, more time consuming
ADV: But better dentistry with these
3 step etch and rinse adhesive process:
- phosphoric acid 32-38% to remove smear layer (microretentive pattern)
- rinse (to remove it)
- decalcify enamel and dentin and expose collagen fibrils
- then primer containing reactive hydrophilic monomers in ethanol or acetone or water, is used to penetrate into dentinal tubuli to replace what was etched to create hybrid layer (hydrophobic)
- a non-solvated unfilled/filled resin bonding agent contains hydrophobic monomers such as Bis-GMA, combined with hydrophilic molecules such as HEMA
composite resin cement
————————————-bonded
adhesive - hydrophobic resin unfilled
————————————-bonded
hybrid layer
————————————
dentin
Self etch Vs Etch and rinse techniques:
Etch and rinse:
- aggressive etching / harsh etching process
- penetrates tubuli so can cause post operative sensitivity
- dissolves/removes smear layer
- dissolves hydroxyapatite crystals in collagen network
- exposes intertubular and peritubular collagen
- opens tubules
- decreases surface-free energy
Self etch:
- doesn’t dissolve/remove smear layer
- no opening of dentinal tubuli
- movement of dentinal fluid in dentinal tubules is prevented so
- minimal risk of post operative sensitivity
- hydroxyapatite crystals remain in collagen network thus prevents hydrolysis
- weaker bond than E+R, causing the composite to separate from enamel
what’s stopping the composite from getting close to the tooth?
smear layer
Resin-modified glass ionomer cement =
light cured GIC
- better aesthetics
- easier process
- better binding to composite
SOS
Etch and rinse Vs Self etch approach:
Etch and rinse:
- 2 step don’t contain a final hydrophobic bonding agent layer; they contain solvents and hydrophilic components from the primer that are mixed with the hydrophobic monomers from the bonding agent
- only 1 bottle containing hydrophobic and hydrophilic so total=hydrophilic
- then it becomes hydrophobic after the evaporation of the solvent
- the hydrophobic monomers from bonding agent and hydrophilic components from primer MIXED together
- hydrophilicity goes together with acidity which make it quickly to degrade thus FASTER DEGRADATION IN MOUTH
- mixing chemistries together so not so good
- easy and fast (single purpose)
Self etch:
- no etching or rinsing needed
- smear layer is not removed
- both interaction of dentin and etching of enamel depend on pH OF THE ADHESIVE which is an important parameter for these adhesives
- etching of enamel not adequate
- more superficial interaction of dentin and smear layer
What is the result of curing before placing the restoration?
it may create problems, such as pulling of the bonding agent
-getting it cured and then not letting the restoration sit properly
1 step self etch adhesives DISADV:
- very acidic and very hydrophilic even after light curing, they behave as semipermeable membranes
- water tree formation: water from dentin will penetrate the adhesive, b/w composite and adhesive will destroy the bond quickly
- very fast water degradation due to hydrophilicity
- INCOMPATIBLE TO SELF CURE RESINS
- hydrolyze fast in the bottle b/c they are hydrophilic so be careful
Universal characteristics, adv, disadv:
- 1 bottle self etch adhesive
- with/without etching, contains acidic monomers
- direct and indirect restorations
- with/without light curing
- for all substrates - contain silane primer and MDP-10(it protects protein metalloproteinases)
- mild etching
- contain amine free dual cure activator
adv:
- easy to use
- better than the first 1 step self etch system
disadv: NO FORMULATION CHANGE that solves the problems of the 1 step self etch adhesives
- nanoleakage (=water coming out of dentin, existing b/w tooth and composite)
SOS
Acidity of self - etch systems (pH) - 4 types:
- mild etching: pH > 2.5
- moderate etching: pH approx 2
- aggressive etching: pH 1-2
- very aggressive etching pH < or equal to 1
-we don’t use strong self etch systems, we use mild etching
What happens when we apply phosphoric acid to dentin?
once it is applied it reacts with calcium of hydroxyapatite and creates CaPO4 ions and some hydroxyl ions. then rinse with water and the ions are gone. decalcified hydroxyapatite ready to accept the dentine
When pH is < 2:
- hydroxyapatite demineralization
- collagen fibrils exposed
- incorporation of instable CaPO4 that are not rinsed away (unstable in water env)
SOS
When pH is > or equal to 2:
- mild (acid) etching system
- protection of collagen due to maintenance of hydroxyapatite
- ionic interaction with hydroxyapatite
- can get chemical bond
- high stability of dentin bond
- inadequate bond to enamel (insufficient etching)
- selective etch: a separate etching step of enamel is greatly improving the bond !!!!!!!!!!
What are the 2 types of resin cements?
conventional resin cements
self-etch / self-adhesive resin cements
SOS
conventional resin cements Vs self-etch/-adhesive resin cements:
conventional resin cements:
- require an etch and rinse or self etch bonding agent (SELF ADHESIVE RESIN CEMENTS DO NOT)
- bond to tooth structure (SELF ADHESIVE RESIN CEMENTS DO NOT)
- they come in dual cure, light cure, self cure (SELF ADHESIVE RESINS ONLY DUAL CURE)
- usually in multiple shades (SELF ADHESIVE RESIN CEMENTS DO NOT)
- better mechanical properties
- solubility best given with conventional resin cements
- may have water soluble try-in pastes (important in single unit veneers)
- for non-retentive preparations
self-etch/-adhesive resin cements:
- do not require the use of bonding agent so super easy to use
- not a big selection of shades (1 or 2)
- no need for bonding on tooth b/c phosphoric acid is grafted in resin cement
- usually dual cure
- are acidic and contain hydrophilic primers in the cement/composite (they are supposed to be acidic after they set)
- contain MDP-10 (CONVENTIONAL RESINS DO NOT)
- similar or slightly higher than conventional resin cements (strengthwise)
- they adhere to tooth structure
- similar to self etch 1 step systems
-both should be compare to their uses and their strengths
How much of a remaining thickness of dentin we need to place a cement?
- If the remaining thickness of dentin is less than 2 mm between the pulp and the pulpal floor, we will place GI or RMGI cement as a liner
- The goal is to seal deep dentin and have 2 mm of dentin + liner between the pulp and the restorative material
What is the use of pre-treatment of restorations?
to increase the adhesion of the restoration to the teeth
SOS
Pre-treatment of restorations:
- microetching (sandblasting/air abrasion) we always perform sandblasting it gives higher bond for emax press
- etch them with hydrofluoric acid and then apply silane primer (important ONLY for PORCELAIN restoration fractures)
- zirconia/metal primers (MDP-10 mainly)
SOS
Microetching:
- Increasing bonding surface by microabrading and roughening
- Usually 50μm Al2O3 powder
- To all indirect restorations
- Be very careful with thin porcelain veneers
- Ask lab to return all restorations sandblasted / microetched
SOS
Porcelain bonding:
- will allow the cement to spread in a more uniform layer
- acid etchable / non-etchable materials
- acid etching with hydrofluoric acid (increases bond strength to porcelain) and application of silane primer on HF etched porcelain
SOS
Which silica based ceramics can be hydrofluoric acid etched, followed by silane primers?
feldspathic porcelain
leucite-reinforced ceramics
lithium disilicate ceramics
- silane coupling agents used
- all these are silica based ceramics - etchable materials (prior to their use, etch them with HF acid and then silane primers, before you bond them)
- should be cemented with adhesive resin cements?
SOS
Silane coupling agents (γ-MPS):
- bonds to porcelain and resin cement
- strengthens the bond of silica based ceramics to tooth structure
- promote adhesion between materials
- 1 or 2 bottles
- pre-hydrolised version might work a little better
- improve the retentiveness to the tooth
- used with Tribochemical silica coating for Zirconia pre treatment
-Silanes allow for stronger bonding of the filler to
the matrix
-Strength of composite resin is highly
dependent on the ability of the coupling agent to transfer stresses from the weak matrix to the strong filler particles
SOS
Zirconia/Metal primers:
is the same thing; zirconia has metal ions as well
- can’t bond to the tooth b/c its a non-etchable material
- bonds to zirconia and resin cement
- MDP-10 (zirconia restorations have this) - the phosphate ester group of MDP chemically bonds to metal oxides and zirconia based ceramics, contains some phosphoric monomers that will somehow bond to zirconia
Gluing process: etching of restorations / teeth
- SMEAR LAYER formed by drilling with bur, fills the orifices of the dentin tubules forming smear plugs which decrease the dentin’s permeability
- PHOSPHORIC ACID gel applied on enamel first and then dentin. this will remove the smear layer from the cavity walls
- so a PRIMER is added to remove water from dentin in order to dry out protein strands b/c water prevents the ‘glue’ from distributing well w/in the dentin
- proteins now are collapsed even though they are dried so an ADHESIVE is added to bring them up again and promote ‘glue’ distribution
- bonding agent=pre glue, is thin and clean so it penetrates deep the protein strands and pores of dentin - the actual glue is applied (need an isolation for good bonding so use rubber dam to avoid saliva and blood coming in contact with the tooth - pores will close so the glue wont be able to penetrate the tubules)
glued ceramic inlays cannot even be recognized by a dentist
How do we remove smear layer from the cavity walls before the application of GIC?
using phosphoric acid gel
What are the components of hybrid layer?
primer and collagen fibers
SOS
Zirconia pre-treatment:
- air abrasion (by changing the Al2O3 particles) and then Zr2O3 primer
- tribochemical silica coating and silane coupling agent to achieve chemical bonding to the silica coated surface
SOS
Tribochemical silica coating
=
process:
=procedure coating the inner surface of Zr2O3 with the impact energy of blasted silica particles
- best possible treatment of bonding zirconia restorations
- special equipment needed with different particles, not widely used
- it is sandblasting but with different particles
- not only you increase the surface area but you also treat the material at the same time
process:
1. silica particles bind to zirconia surface
2. you abrade it and part of silica remains in zirconia
in order to get silane primer on the surface
3. you can now etch and apply silane primer and bonding strength to zirconia
SOS
for porcelain restoration microetching you apply:
HF-, silane primer and resin cement
SOS
for zirconia restoration microetching you apply:
MDP primer and then resin cement
SOS
for metal restoration microetching you apply:
apply metal primer and then resin cement
SOS
How to apply resin cement on the tooth:
pumice (with rubber cap) then add bonding agent (dual cure) and then resin cement
SOS
During bonding process:
mixing cement, fitting restoration, light pressure, check fit and occlusion (ask pt), light cure and then remove excess
Why we don’t apply hydrofluoric acid etch and silane primer in composites indirect restorations?
b/c its already in the composite
Post cementation process:
- remove GP according to the selected size
- drill according to selected post size to make space in the cavity (do not overdrill)
- try in the post using gates glidden (3-4 mm to the apex)
- verify depth (fit the post to see if it goes the same depth)
- take x-ray - post needs to be stable without any movements
- trim the post before cementation
- etch, rinse, leave moist (use paper points to remove excess)
- place bonding agent (use paper point) with dual curing (since light does not travel all the way into the RC)
- place resin cement in the canal
- place the post with gentle pressure
- light cure
- use sponge and paper points to make sure the bonding agent is reached all the way into the RC space
- build up simultaneously with composite or core build up flowable composite
- prep the tooth for a crown
- place temporary crown while we wait for the permanent to come
- remember the ferrule !!!!!!!!! (ferrule might fail no matter what material restoration you use)
- we use only the hydrophobic resin, not the primer since we don’t have any dentin/resin (hydrophilic)
- hydrophobic resin: to wet the post to increase the coating of post to resin cement
- prefer dual cure
- bonding agent on post
- we use both light and dual cure to secure everything in place
- directly after we bond. light cure for a few sec the post to secure the place
- if you use zirconia post, sandblast it to increase the bond of the post
Porcelain veneer bonding:
- done for aesthetics
- most difficult procedure
- non retentive restoration (conventional resin?)
- very long lasting
- be careful not to bond the teeth together b/c the porcelain veneers run all over the contact and also you have a limited time and you might not notice that they are not sited in the correct place
- try - in pastes (LC cements need these)
Oral Mucosa =
mucous membrane covering all oral structures except teeth, consisting of 2 layers:
- str. sq. ep. - may be keratinized, parakeratinized or non-keratinized, depending on its location
- supporting CT
How is Oral Mucosa classified?
in 3 functional types:
- lining / reflective mucosa
- specialized mucosa
- masticatory mucosa
SOS
Masticatory mucosa =
comprises the free and attached gingiva and the mucosa of the hard palate
-(keratinized)
Lining or reflective mucosa =
is a thin, movable tissue with non-keratinized epithelium
Specialized mucosa =
covers the dorsum of the tongue and the taste buds
When do we have a risk of recession?
low risk:
high risk:
lower risk of recession: keratinized gingiva
higher risk of recession: non-keratinized gingiva
SOS
Free gingiva =
the gingiva that extends from the marginal crest to the level of the base of the gingival sulcus (outer wall keratinized, inner wall non-keratinized)
Gingival sulcus =
the space between the tooth and the free gingiva
-The outer wall of the sulcus (inner wall of the free gingiva) is lined with a thin, non-keratinized ep (sulcular epithelium)
Free gingival groove =
a shallow groove that runs parallel to the marginal crest of the free gingiva and usually indicates the level of the base of the gingival sulcus
SOS
Attached gingiva =
a dense CT with keratinized epithelium that extends from the depth of the gingival sulcus to the mucogingival junction / a dense network of collagen fibers connects firmly the attached gingiva to the periosteum of the alveolar bone and hard palate and to the supra-alveolar cementum of the root of each tooth
-it is separated from the (alveolar) mucosa by the mucogingival junction
SOS
Mucogingival junction =
is the junction of the keratinized gingiva with the alveolar mucosa, which is thin, mobile, darker red, and non-keratinized
Vertical width (or zone) of keratinized gingiva:
refers to the distance from the free gingival margin to the mucogingival junction
-free and attached gingiva
Recession problems:
aesthetics, root caries risk, high sensitivity, loss of tooth structure like erosion and abrasion from that area is very high
What is the result of keratinized tissue deficiency?
it predisposes to the development of gingival recession and inflammation
How many mm of keratinized gingiva is needed for optimal health around the teeth?
≥2 mm of keratinized gingiva, with at least 1 mm being attached
-a minimal dimension of attached gingiva might be acceptable only for the plaque-free, non-restored environment without prominent roots
When is gingival augmentation indicated?
for sites with minimal or no gingiva that are receiving intracrevicular restorative margins
-every time you have intracrevicular you should do gingival augmentation to avoid recession
SOS
The rational for performing gingival augmentation procedures around natural teeth includes:
- Facilitating plaque control
- Improving patient comfort
- Increasing the zone of attached gingiva in conjunction with restorative, orthodontic or prosthetic dentistry
- Helping prevent future recession
How to locate the mucogingival junction?
- stretch the lip/cheek and at the same time probing the gingival sulcus
- gently push the alveolar mucosa coronally with periodontal probe and observe where the tissue stops moving
Papilla characteristics:
anteriors:
posteriors:
- has triangular shape between anterior teeth
- has a mountain range, with facial and lingual peaks and the col (“valley”) lying beneath the contact area, in posterior teeth
What is a col?
a concave area beneath the contact, is more vulnerable to periodontal disease because it is covered by non-keratinized ep
In a mouth without effective oral hygiene procedures:
-both SULCUS AND PAPILLA are SUSCEPTIBLE TO INFLAMMATION due to plaque accumulation because
the epithelial lining of the sulcus and of the papillary col are non-keratinized
-the dense, highly stable, keratinized gingiva (free and attached) are more resistant than alveolar mucosa to mechanical and bacterial insult
SOS
Periodontium basic biotypes:
thin Vs thick gingival biotypes:
thin gingival biotypes:
- probe tip can be visualized through the gingival sulcus when is placed
- high risk of gingival recession during any dental procedures
- more shrinkage with subgingival restoration
thick gingival biotypes:
- probe tip can not be visualized
- low risk of gingival recession during any dental procedures
- less shrinkage with subgingival restoration
- can both exist in the same mouth
- the thicker the alveolar bone and gingival tissue, the more stable bone and free gingival margin
SOS
Thin Vs Thick biotype characteristics:
Thin biotype:
- thin marginal bone
- narrow zone of keratinized gingiva
- pronounced scallop of gingiva and bone
- triangular tooth forms
- small proximal contacts located near the incisal edge
- gingival recession after disease
Thick biotype:
- thick marginal bone
- large zone of keratinized gingiva
- flat scallop of gingiva and bone
- regular tooth forms
- broad proximal contacts located more apically
- deep pocket and intrabony defect formation after disease
Thin scalloped biotype:
crown shape cervical shape keratinized tissue zone gingiva shape alveolar bone shape
slender triangular crown subtle cervical convexity interproximal contacts close to the incisal edge and a narrow zone of keratinized tissue clear thin delicate gingiva a relatively thin alveolar bone
-can see the perio prbe
Thick flat biotype:
crown shape cervical shape keratinized tissue zone gingiva shape alveolar bone shape
more square-shaped tooth crowns pronounced cervical convexity large interproximal contacts located more apically a broad zone of keratinized tissue thick, fibrotic gingiva a comparatively thick alveolar bone
-cannot see the perio probe
Thick scalloped biotype:
crown shape
keratinized tissue zone
gingiva shape
thick fibrotic gingiva
slender teeth
narrow zone of keratinized tissue (KT)
a pronounced gingival scalloping
The Biologic Width =
combined vertical dimension of the junctional epithelium and the supra-alveolar CT
-do not violate the biologic width by placing restorative margins within or apical to the junctional ep
= 2.04 mm
Signs of BW violation:
Chronic inflammation around the restoration Bleeding on probing Gingival recession Pocket formation Alveolar bone loss Localized gingival hyperplasia
sulcular epithelium =
- lines the gingival sulcus
- is apically bounded by the junctional ep and meets the ep of the oral cavity at the height of the free gingival margin
- non-keratinized
junctional epithelium =
/epithelial attachment = is adherent to the tooth surface
- non-keratinized
- more sensitive to trauma since is non-keratinized
How to identify the biological width?
-by probing under local anesthesia to the bone level
and subtracting the sulcus depth from the resulting measurement
-take the probe, put it in sulcus and it may cause trauma but it is fine, push it to the crestal bone
-sound technique
The margin of a tooth preparation should not be positioned _ unless:
subgingivally unless dictated by caries, previous restoration, aesthetics, or specific preparation requirements
What should be evaluated prior to restorative or orthodontic treatment?
amount of free and attached gingiva
gingival biotype
biologic width
mucogingival condition
How to re-establish BW?
crown lengthening or orthodontic extrusion
Periodontal Ligament =
is a multifunctional unit of CT that occupies the space between the cementum and alveolar bone
-its width varies from 0.15 to 0.4 mm and is adapted to functional demands within this narrow range
Periodontal Ligament functions:
(1) Attachment and support: Bundles of collagen fibers, known as principal fibers of the ligament, connect between cementum and alveolar bone to suspend and support the tooth
(2) Sensory: Coordination of masticatory m function is achieved by proprioceptive mechanism, from the sensory nerves located in PDL
(3) Nutritive: Blood vessels supply the attachment apparatus with nutritive substances
(4) Homeostatic: Specialized cells of the ligament function to resorb and replace cementum, PDL, and alveolar bone
When should mucogingival surgery be considered?
in areas that you don’t want any further recession or to avoid recession in areas where I want the pt to perform better OH
Why is the amount of faciolingual movement important for each maxillary tooth?
b/c when you do fixed bridges that micromovement of the teeth is a reason for DECEMENTATION so its not good to use a lot of teeth as abutments
-if one tooth is decemented then the risk of caries is higher
SOS
What are the main causes of poor gingival response to restorations?
•Lack of optimal periodontal health before treatment
•Inadequate OH before, during and after treatment (it will always affect the prognosis and i want to create an environment that is cleanable) !!!!!
•Excessive trauma during treatment
•Poor contour, fit / marginal adaptation and surface smoothness of direct and indirect restorations (provisional and definitive) -> cause plaque accumulation and poor OH access
-the smoother the surface the less plaque
Adequate tooth reduction is essential for:
aesthetics, structural integrity of the restoration and to avoid overcontouring (overcontour is the worst for gingival response, results in plaque accumulation and interferes with OH)
- Care must be exercised not to traumatize gingival tissues during preparation
- There is no consensus regarding an ideal finish line
Prosthetic Margins Integrity:
what do you expect there?
acceptable margins _ μm:
cement film thickness should be _ μm:
•always expect plaque accumulation at margins
•acceptable margins between 30-200μm
•cement film thickness should be 40 μm, and in order for an explorer to effectively detect a gap larger than 40 μm, its tip should be equal or less than that number (need a sharp explorer; not thicker than that)
-there’s always a small gap b/w tooth and the margin
-overhangs are worse than open margins
Overhang Vs Open margin Vs Negative Margin:
Overhang:
- if step from a direction of: root to occlusal
- plaque accumulation and worst for soft tissues
Open margin:
- both directions (stucked)
- plaque accumulation, risk of caries is high and leakage
Negative Margin:
- if step from a direction of: occlusal to root
- plaque accumulation and risk of caries is high
-for open margins and negative margins the soft tissues are not so bad
•overhangs (especially when subgingival) maybe worst than open margins for periodontal health
Prosthetic Margins Placement:
where to place it?
- placed coronal to or at the level of gingival margins
- intracrevicular margin is always a compromise
- if margins placed subgingival; just inside the sulcus !!!!!!! (not further than 0.5 mm)
- difficult to identify marginal discrepancies when margins subgingival
- always prefer supragingival margins
- 3 mm distance from crestal bone so that you
- do not violate BW
- minimize soft tissue trauma during all the steps of the restorative procedures
Anatomical form of Restoration =
= the degree to which the restoration duplicates the original contour of the intact tooth
Common problems with the anatomical form of restoration:
overcontouring, undercontouring, uneven or flat marginal ridges, inadequate facial and lingual embrasures, and lack of occlusal or gingival embrasures
The critical factor in determining the need for replacement is: (contour)
whether pathosis has resulted, or is likely to result, from the poor contour
-not whether the contour is ideal
Most common error of Cervical contour:
overcontouring (usually because of lack of space)
-it is causing soft tissue impingement and plaque accumulation which then result in gingival inflammation
- Undercontouring rarely show signs of gingival inflammation
- NEVER prevent access for oral hygiene !!!!!!!
SOS
Emergence profile:
=
=the profile of the restoration as it emerges from the gingival sulcus
- do not create any over contour restorations at that area
- should be straight for the first 0.5 mm
- sub-gingival margins, need to follow the root anatomy and in furcation areas should be barrelled in to allow easier oral hygiene
- sometimes we may lose aesthetics, but OH is better to have always
Interproximal Contour:
- Critical for the shape and health of the papilla (especially when roots of adjacent teeth are very close together)
- Should not impinge on soft tissues (do not overcontour)
- Should not reduce access to oral hygiene as OH has significant effect to papilla health
- Should be an S shape
SOS
Ideal proximal surface:
- Permits access for OH
- Does not compress papilla
- Allows proper phonetics and aesthetics
- Is in harmony with adjacent teeth
- Provides effective, properly located and shaped proximal contacts
- Prevents food trapping
Open Proximal Contacts:
- result in food trapping which is uncomfortable for the patient, poor aesthetics and poor phonetics
- restore (close) them as long as overhangs are not created
- the greater occurrence of food impaction is associated with increased PD in these areas
Exceptions to the rules of overcontouring (with caution):
Increased interproximal subgingival contours done in order to:
Increased facial contours done in order to:
- Increased interproximal subgingival contours in order to increase papillary height (more occlusally)
- Increased facial contours in order to position the gingival tissues more apically (more apically; effect like recession)
-to close the black triangles and put the margins higher up
SOS
Overhanging dental restorations:
The permanent calculus:
what’s the problem?
how it is improved?
what is related to its size?
-problem with Class II direct restorations, is the overhang, an extension of the restorative material beyond the cavity preparation
•The morphological variation in the cervical aspect of teeth, including furcations, convexities and concavities, makes it difficult to consistently place a wedge and matrix band to fully adapt to the gingival cavosurface margin
- Radiographic, tactile exploration and explorer needed to improve their detection
- Increased bone loss, attachment loss, pocket depth, and inflammation occur adjacent to teeth with ODRs; the periodontal destruction is related to the size of the ODR
SOS
Aetiology of Gingival black triangles:
- Inter-proximal space between teeth
- The distance between inter-proximal contact position to bone crest
- Gingival biotype
- Patient’s age
- Periodontal disease and loss of attachment, resulting in recession
- Diverging roots
- Tooth morphology and abnormal crown and restoration shape
- Considered aesthetically unacceptable
- Multifactorial aetiology
- Range of treatment options
Papilla tip:
how many mm?
water balloon effect?
if distance less than 5 mm:
if distance more than 5 mm:
- The tip of the papilla should extend 4-5 mm above the level of the interproximal bone !!!!!!!!! - to minimize black triangles
- When pressure is applied to certain areas of a water balloon, the balloon simply swells elsewhere. The interdental papilla demonstrates a response very similar to the water balloon
- First, measure the distance from the papilla tip to the bone crest
- If the distance is less than 5 mm, compress the balloon by adding restorative material to the mesial and distal tooth walls lateral to the papilla. This will push the balloon (papilla) coronally up to the 5 mm distance from the bone crest
- If the distance from the bone to the papilla is 5 mm or greater, the contact point must move apically to the top of the existing papilla
- When adjacent roots diverge, the contact point has moved coronally, and the interproximal embrasure is enlarged
- Orthodontic movement to parallel the roots will improve the contact location, narrow the embrasure, and result in a taller, more pointed papilla
What can secure the long-term success of periodontal treatment and restorative treatment?
maintenance therapy
SOS
THERAPEUTIC GOALS OF PERIODONTAL MAINTENANCE:
- To prevent or minimize recurrence of disease progression
- To prevent or reduce the incidence of tooth or implant loss by monitoring the dentition and prosthetic replacements of the natural teeth
- To increase the probability of locating and treating other conditions or diseases found within the oral cavity in a timely manner
The further the margin is from the gingiva:
prevention by which measurements?
the easier the access for plaque removal and the healthier the gingival tissue will be
- Toothbrush is cleaning 100% the biofilm
- Important to finish the restoration supragingivally
- Toothbrush can only go 0.5 mm below the gingiva
- The floss goes deeper than the toothbrush in sulcus
What is the most important factor responsible for initiation of periodontal disease?
Plaque-retentive properties of the restorative materials
SOS
Periodontal responses are mostly affected by _ instead of _:
roughness threshold Ra:
the surface roughness of the restorative material (not the type of material)
A minimum roughness threshold Ra < 0.2 μm has been suggested to minimize plaque retention on restorative materials
Plaque on restorative materials and how polishing affects it:
Porcelain seems to retain less plaque compared to other restorative materials as its highly polished surface inhibits plaque formation and permits its rapid removal
SOS
Furcation Involvement:
how to check for it:
limitations:
Furcation = when tooth is losing bone around that area
- CRUCIAL b/c is related to tooth prognosis
- The degree of furcation involvement dictates the treatment for the tooth
- Limited access due to soft tissue coverage and adjacent teeth (especially in maxillary molars) for OH
- If roots are diverging: more space to go and examine the furcation
- For proper diagnosis, thorough clinical and radiographic examination is needed - don’t rely on x-ray b/c they are 2D thus need to examine clinically with Nabers probe (12 mm curved probe with 3 mm markings)
- Placing the tip of the Nabers probe against the tooth and moving it in an apical direction aids in detection of furcation involvement
Hamp classification for the Furcation involvement:
Grade I:
Grade II:
Grade III:
• Grade I: horizontal penetration of the Nabers probe less than 3 mm
• Grade II: horizontal penetration of the Nabers probe more than 3 mm, but not through the furcation
-can go deeper into the furcation, but not through the furcation
• Grade III: when the lesion is through and through, Nabers probe penetrates from buccal to lingual
SOS
Types of root trunks:
Which one to use for crown lengthening?
•Type A: the shortest root trunks, involving a third or less of the cervical area of the root
•Type B: root trunks include up to half of the length of the root
-if I remove 2 mm for the furcation is not going to be bad for the prognosis
- Type C: the longest root trunks where the furcation entrance is at the apical third
- For crown lengthening procedure we prefer types b or c b/c it gives you more root to work on
Malpositioned teeth OH:
- More difficult OH and so more plaque accumulation and gingival inflammation (cross-bite, misalignment / rotation, crowding)
- When OH is adequate, tooth malposition is not a significant factor
SOS
_ mm interproximal root distance (IRD) - risk factor:
< 0.8 mm is a significant local risk factor for alveolar bone loss in mandibular anterior teeth
Enamel Pearls:
- Ectopic globules of enamel adherent to the tooth consisting primarily of enamel, dentin and pulpal tissues
- Vary in dimension from 0.3-2.0 mm
- Most often in furcation regions of maxillary M2 and M3
- Highly associated with attachment loss and its removal is thus indicated
SOS
Cervical Enamel Projections (CEPs):
- Ectopic deposits of enamel apical to the CEJ with a tapering form and extending toward or entering the furcation
- They are an etiologic factor in furcation defects since CT doesn’t attach to the enamel so immediately you have a pocket there because of the anatomy of the tooth leading to plaque accumulation and compromised OH !!!!!!!!!!!
- Their removal or at least reduction is indicated. However, this should be done carefully to avoid irreversible damage to the tooth
Masters and Hoskins classification system for Cervical Enamel Projections:
Grade I:
Grade II:
Grade III:
- Grade 1: Short but distinct change in the contour of CEJ extending toward the furcation
- Grade 2: CEP approaches the furcation, without making contact with it
- Grade 3: CEP extends into the furcation
Cemental Tear:
what is it?
treatment for it?
- A fragment of cementum that detaches from the tooth, usually after trauma, causing isolated bone loss (vertical bone defects)
- Surgical debridement, removal of cementum fragment and periodontal regeneration
Palatoradicular Grooves (Developmental grooves):
what are they?
consequences?
prognosis?
treatment?
- A developmental anomaly in which a groove passes from the cingulum of maxillary incisors apically onto the root
- 43% of grooves do not extend more than 5 mm apical to the CEJ
- Facilitate the accumulation of biofilm in the depth of the groove which is an area inaccessible to both patients and clinicians
- The prognosis for involved teeth, with diagnosed bone loss around the area, is poor
- Treatment: odontoplasty to remove or reduce the groove, or the groove may be restored with a biologically restorative material
SOS
Occlusal trauma:
=
where does it occur?
when does it get higher?
= injury from functional or parafunctional occlusal forces, resulting in tissue changes within the periodontium (injury to periodontium)
- may occur in an intact periodontium or in a reduced periodontium due to periodontal disease
- consensus exists that traumatic occlusion is not an initiating factor of periodontal disease BUT can act as a contributory factor
- if your patient is a bruxist then the chances of occlusal trauma are higher
SOS
Proposed clinical and radiographic indicators of occlusal trauma:
fremitus mobility thermal sensitivity PDL space widening fractured tooth tooth migration occlusal discrepancies wear facets cemental tear root resorption discomfort/pain on chewing
- Excessive occlusal forces do not initiate plaque induced periodontal disease or loss of periodontal attachment, and more recent studies support this conclusion
- There does not appear to be any scientific evidence to prove that excessive occlusal forces cause abfraction or gingival recession
Crown lengthening:
=
goal:
the removal of bone tissue together with removal or
repositioning of the soft tissue around the tooth
-The goal of this therapy is to increase the clinical crown and consequently preserve the biologic width
-involves bone removal
Gingivectomy:
unlike crown lengthening, gingivectomy does not involve hard tissues but rather just gingival excess removal to expose the clinical crown
-does not involve bone removal
Distal wedge:
- is commonly performed on the distal surface of molars to facilitate hygiene, access and help eliminate periodontal pockets, or facilitate access for proper restorative treatment
- excess tissue around the D side of Molars leading to no space and plaque accumulation there and difficult to access
Non-carious cervical lesions:
=
These lesions may need intervention, due to:
= loss of tooth structure at the cervical area of a tooth due to abfraction, abrasion or erosion
•These lesions may need intervention, due to:
(1) Aesthetic problems
(2) Tooth sensitivity that does not resolve with other treatment options
(3) The lesion is progressing and there is risk of pulpal exposure
(4) The lesion is progressing and the tooth integrity is at risk
In a healthy smile the lip:
the lip rises to reveal 1-2 mm of gingiva of anterior teeth
•When more than 2 mm of gingival tissue is revealed upon smiling this is described as a “gummy smile” and is considered unaesthetic
Altered passive eruption:
=
result:
= delayed migration of the gingival margin
-results in excessive gingival display (excess soft tissue) and short clinical crowns
Smile Line:
High smile line:
Medium smile line:
Low smile line:
High smile line: 100% of clinical crowns and continuous strip of gingival tissue are exposed
Medium smile line: 75%-100% of clinical crowns and interdental papillae are exposed
Low smile line: <75% of clinical crowns and no gingival tissue are exposed
-this is important b/c small recessions or black triangles will not satisfy the pt
Gingiva Line:
=
where should central or lateral incisors be on that line?
- A straight line is drawn from the tooth-gingiva interface of the right and left maxillary canine
- The tooth-gingiva interface of both central incisors should be on this line
- The tooth-gingiva interface of the lateral incisors may either fall on this line or be up to 1.5 mm below it
Bonding agents:
1,etch
- primer
- bond
- fill it
- LC
bonding agents = resin materials used to make a composite filling material adhere to both dentin and enamel
- consists of only resin, w/o any fillers
- contains mostly hydrophobic Bis-GMA
etch= applied to remove parts of the tooth structure; removing inorganic components or minerals and so in enamel we removing hydroxyapatite and in dentine we remove also hydroxyapatite and we are leaving collagen fibers in dentin
primer= contains solvent and monomer, solvent carries monomer into the tooth (into these micromechanical areas we created with the etch) and also lets the adhesive attach to the tooth as well
- when you add it to the surface it penetrates into the dentinal tubules, infiltrates the collagen fibers and makes the hydrophobic layer on the surface
- has both hydrophilic and hydrophobic parts
adhesive= has a component to allow it to cure inside the tooth
How durable is the bond of the universal adhesive to the substrate(enamel, dentin, composite, metals) we want to bind it to?
on enamel: always better bond if you use phosphoric acid first
-any self etching adhesive will have a better bond to enamel if you use phosphoric acid on enamel first
on dentin: no difference
on composite: adhesives on composites create a very good bond
-universal adhesives have silane coupling agents
What is an MDP?
= phosphate monomer that makes the adhesives more compatible with zirconia and other types of metals
-it increases the stability of the bond and helps us also to bond zirconia
Why do we need the hydrophobic layer?
-dentine surface is hydrophilic after etching so if you don’t make the hydrous layer, the composite won’t stick
AND
-b/c we don’t want the water permeability that allows water trees to be formed b/w the composite and adhesive
SOS
What bonding system do we need to use?
- Low technique sensitivity
- H3PO4 enamel etching
- Mild self etching if SE
- We want a final hydrophobic layer
- Not acidic after curing (acidic is hydrophilic)
- Dual Cure
- 10-MDP
SOS
Bonding systems - In order of usage:
components of each:
1st: 2-Step SE with SEE
- Self-etching primer and Bonding resin
2nd: 3-Step ER
- Phosphoric acid, Hydrophilic primer and Bonding resin
3rd: Universal - 1-Step SE with SEE
- Self-etching hydrophilic primer/bonding resin
4th: 2-Step ER
- Phosphoric acid and Combined (hydrophilic primer + bonding resin)
SOS
Which is keratinized and which is non-keratinized epithelium?
keratinized:
outer wall of free gingiva
attached gingiva
masticatory mucosa
non-keratinized: lining/reflective mucosa gingival sulcus epithelium inner wall of free gingiva mucogingival junction epithelial lining of the sulcus and of the papillary col sulcular epithelium junctional epithelium alveolar mucosa
Smear layer consists of:
- Enamel debris
- Micro organisms
- None of the above
- All of the above
-All of the above
The adhesive systems should have:
a hydrophilic end which readily wets and penetrates into the porosities of dentin, reacting with their organic or inorganic components; and a hydrophobic end which bonds to the composite resin
The “biologic width” is the distance between the
A. Base of the gingival sulcus and the crest of alveolar bone
B. Free gingival margin and the base of the gingival sulcus
C. Free gingival margin and the alveolar bone
D. Free gingival margin and the mucogingival junction
E. Free gingival margin and the base of connective tissue attachment
A. Base of the gingival sulcus and the crest of alveolar bone
In comparing conventional glass ionomer restorative materials with light-curing glass ionomer (resin ionomer) materials, which of the following physical properties of the light cured materials are improved?
- bond strength to composite
- thermal coefficient of expansion
- solubility
- compressive strength
a. 1,2,3
b. 1,2,4
c. 1,3,4
d. 2,3,4
e. all of the above
c. 1,3,4
Primers are:
- monomers
- acidic
- hydrophilic
- water is always a component of acidic primer
= displace water and allow the monomers to penetrate the dentinal collagen matrix
Dentin bonding primers: transforms hydro______ to hydro______
hydrophilic to hydrophobic
Cements are ____ soluble than the overlying restoration
more
less
equally
none of the above
more
Etching of dentin does not include : A. Removal of smear layer B. Exposure of collagen fibres C. Opening of dentinal tubules D. Increases surface energy
D. Increases surface energy
Acid etching transforms the smooth enamel into an irregular surface and increases its surface-free energy
The most important factor for good prognosis when placing a post is:
the ferral effect
MDP-10 found in:
zirconia primers
universal adhesives
self etch/self adhesive resin cement
Resins are:
hydrophobic
Etch for 15 seconds to:
– remove the smear layer
– Demineralize intertubular and peritubular dentin
– Expose collagen fibrils
Acidic and hydrophilic are:
self-etch/-adhesive resin cements
primers
1 step self etch
Bonding to enamel:
Bonding to dentin:
Bonding to enamel:
- tooth needs to be DRIED before placing the bonding agent
- we don’t want a hybrid layer b/c enamel, bonds perfectly to bonding agent; so no need to use a primer
etch with phosphoric acid for 15 sec first on enamel and then on dentin, rinse and then dry
Bonding to dentin:
- no need to be dried in order for the hybrid layer to form
- need to use primer
resins have mechanical properties from fillers, whiles sealants don’t
!
Why do we etch first?
to roughen the surface and create a microretentive pattern (the tooth surface is smooth, but this gel eats its way into the enamel creating pores - these remain even after rinsing the gel off)
- etching pattern is 3D, the gluing surface is enlarged more than what is observed
- etching also done to increase retention, remove smear layer and expose the dentinal tubules
Selective etch technique:
=
process:
= combination of both self etch and etch+rinse
- a separate etching step of enamel is greatly improving the bond !!!!!!!!!!
- eliminates post operative sensitivity and provides bonding for both enamel and dentin
- golden standard goal for composite fillings
- process:
1. phosphoric acid for 15 sec ONLY on enamel
2. rinse for 30 sec -> gives time for the water to neutralize the acidity
3. dry
4. universal adhesive applied to BOTH enamel and dentin
5. dry
6. LC
7. apply composite
Self etching process:
- dentin smear layer is the dust created by drilling
- self etching primer bonds to dentin
- soak smear layer in primer
- no rinsing
- adhesive and composite
- dental adhesive hydrophobic result on top of hybrid layer
2 step self etch with selective etch:
2 step se:
- primer in different bottle than bonding agent
- etching of ENAMEL is not adequate (pH is low) so need to do the SELECTIVE ETCH (before the process of 2 step se)
- then apply self etching primer
- bonding agent
- hybrid layer
Which is hydrophilic and which is hydrophobic?
enamel: dentin: composite: primer: bonding agent: hybrid layer:
enamel: hydrophobic
dentin: hydrophilic
composite: hydrophobic
primer: hydrophilic
bonding agent: hydrophobic
hybrid layer: hydrophobic
Which are the best adhesives?
2 step se (etch and primer together, bonding agent in a different bottle)
3 step e+r (etch acid, primer and bonding agent in different bottles)
So when primer and bonding agent are in different bottles/steps we have a hybrid layer; which is good for bonding
2 step etch + rinse: good or not
-primer (hydrophilic) + bonding (hydrophobic) in same bottle = degradation (NOT GOOD)
Where to use universal?
- direct and indirect
- for everything
- better not to use it, not that good
- can also do selective etch
- 1 step self etch (all in 1)
Which adhesives have hybrid layer?
2 step se: hybrid layer
3 step e+r: hybrid layer
1 step se: no hybrid layer so not good bonding to dentin
2 step e+r: no hybrid layer
-for enamel we don’t need a hybrid layer; only for dentin
A patient needs an enamel restoration, what are the treatment options?
usually nothing, wait for reminilization
A patient has enamel carries, what are the treatment options?
dry completely b/c enamel is hydrophobic
3 step e+r (without the primer though)
(no need for primer; primer is used for dentin)
we don’t want a hybrid layer b/c enamel, bonds perfectly to bonding agent; so no need to use a primer
-used also for a deep restoration
A patient has dentin carries and we need to bond to dentin, what are the treatment options?
partial dry
use a primer and a bonding agent
3 step e+r or 2 step se b/c we want hybrid layer
Direct restorations:
Indirect restorations:
Both:
Direct restorations:
-3 step ER
Indirect restorations: (for all: microetching)
-2 step SE
Both:
-1 step SE (universal)
