Large Restorations Flashcards
what are the options for large restorations
- restore: indirect pulp cap or direct pulp cap
- endo: vital pulp therapy, RCT
- crown lengthening
- crown
- extraction
describe the sensitivity of dentin
the DEJ is an extremely sensitive part of the tooth
describe the hydrodynamic theory of pain transmission
- dentinal tubules are filled with odontoblastic processes and wrapped in afferent nerves and dentinal fluid
- when enamel or cementum is removed during cavity preparation, the external seal of dentin is lost which allows small fluid movements in the tubules
- this causes distortion in the afferent nerve endings, causing pain
hydrostatic pressure changes within the tubules is caused by external stimuli can:
cause pain to the pulp through fluid movement within the tubules
what are the precautions used to protect the dentin
- air- water spray should be used whenever cutting with high speed handpieces to avoid heat build up and destruction of odontoblsatic processes in the dentin
- dentin should not be dehydrated by air blasts
what can dentin dehydration cause
aspiration of odontoblasts into tubules
caries control restorations are performed as part of a larger caries control plan, when one or more of these conditions exist:
- caries is extensive enough that pulpal complications are likely to occur soon
- it is desirable to quickly eliminate large carious lesions that are a source for caries infection in the patients mouth
- time does not permit definitive restoration of one or many large lesions
- the prognosis for the pulp is questionable and definitive restoration should be deferred until the pulp’s condition can be better assessed
caries control restorations refer to a situation when one tooth or multiple teeth at the same appointment are treated quickly by:
- removing the infected dentin
- medicating the pulp, if necessary
- restoring the defects with a temporary material. if a temporary material is used, undermined enamel can be left to better retain the temporary
when is an indirect pulp cap used
when a deep lesion occurs and there is no clinical or radiographic evidence of irreversible pulp damage
tooth should be in what condition for the indirect pulp cap:
- asymptomatic
- at most have symptoms consistent with reversible pulpitis- moderate cold sensitivity
- pain subsiding 15 seconds
the caries is usually ______ than it appears on Xrays
deeper
what is the object of an indirect pulp cap
to avoid a direct pulp exposure
where are liners applied
- to the deepest parts of the preparation closest to the pulp
- away from margins
what are the liner materials
- calcium hydroxide
- resin modified glass ionomer
what are the brand names of calcium hydroxide and when is it used
- Life, Dycal
- use on deepest preps- pulp capping material
what is the brand name for resin modified glass ionomer, how does it cure, and what does it do
- vitrebond
- light cured
- releases fluoride over time
what is the two appointment approach for the indirect pulp cap
- remove all caries, affected and infected dentin, from all areas except the deepest, close to the pulp
- leave the last little bit of infected dentin, cover it with calcium hydroxide and glass ionomer
- place a temporary restoration such as IRM or Ketac silver
- OK to leave undermined enamel temporarily to help hold in the temporary restoration
- wait several weeks (12 weeks)
- confirm the patient is asymptomatic and do vitality test before anesthetizing
- remove the temporary restoration, glass ionomer and CaOH
- carefully remove the remaining infected dentin
- leave the affected dentin using a #4 round bur
- place a new liner of dycal covered by base of vitrebond
- remove undermined enamel, modify the prep
- and restore
when is the two appointment approach done for the indirect pulp cap
- when the removal of all the infected dentin is most likely going to result in a pulp exposure
why do you wait 12 weeks in the two appointment approach for indirect pulp cap
to allow the body to form reparative dentin in the site of the near exposure
- a dentin bridge will form
why do you use a round bur #4 instead of a spoon excavator in the two appointment approach for the indirect pulp cap
- use on slowspeed just above stall speed with a light, shaving touch
- the larger bur will put less force per unit area than the hand instrument would do, therefore making it less likely that one would break through into the pulp
when would it be okay to leave a small amount of infected dentin sealed deep in the cavity beneath the liner and base
if the cavity has been well sealed and the patient is asymptomatic and the tooth tests vital
why are you able to leave infected dentin in some circumstances
the food supply to the bacteria will die and become dormant
- caries progression will be arrested and the pulp will remain in good health
is the single appointment approach or two appointment approach more common in indirect pulp cap
the single appointment approach
describe the single appointment approach
- remove infected dentin, remove affected dentin from any areas where a pulp exposure is not likely to occur
- leave the affected dentin only in the deepest area where the possibly of a direct pulp is a concern
- OK to leave a small amount of infected dentin in deep areas
- place a liner of CaOH over the deepest area
- place a base of glass ionomer over the CaOH. there is fluoride release from vitrabond
- remove all undermined enamel and place the permanent restoration so you dont need to re-enter the tooth and risk an accidental exposure
- if you dont have enough time to place the permanent restoration, place a temporary restoration
- if the restoration is deep and patient maybe had RP, wait several months before crowning if a crown is necessary
if sealed off from the oral environment, remineralization of the _____ dentin is possible
affected
when is a direct pulp cap used
when a small pulpal exposure occurs during cavity preparation
describe a direct pulp cap
a thin layer of CaOH is floated over the exposed pulp
- a layer of glass ionomer is placed over the CaOH to stimulate the pulp to from secondary odontoblasts which can produce a dentin bridge across the exposure site
when is a direct pulp cap most successful
- when the exposure is mechanical rather than carious
- when patient is young and exposure is less than 0.5mm
- if bleeding at the site is easily controlled and there is no pus or serous exudate
- if the area has not been contaminated by saliva
- if there has been little or no mechanical damage to the pulp tissue
why are endodontists not fond of direct pulp caps
because CaOH may cause the canals to calcify over time
what should you do to see if the pulp cap worked
months later radiograph and pulp testing
pulp caps are more effective on what patients
young patients with large pulp chambers and open root canals to provide better circulation to the area where we are trying to induce dentin bridge formation
what part of the pulp do direct pulp caps work better on
tips of pulp horns rather than the side of a pulp chamber
should there be pain after doing a direct pulp cap
mild to moderate spontaneous pain for as much as three days, if there is spontaneous pain remaining then be concerned
how long might cold sensitivity linger after a direct pulp cap
several weeks
if the tooth will require a crown to adequately restore it can you do a direct pulp cap
no do endo
a broken or leaky restoration =
failure because bacteria will leak into the pulp and kill it
all restorations must:
adequately seal the cavity to avoid microleakage, bacterial penetration and recurrent decay
when is the smear layer created
whenever dentin has been cut
how thick is the smear layer and what is it made of
- a few micrometers thick
- denatured collagen, hydroxyapatite and other cutting debris
what does the smear layer do
- acts like a natural bandage over the cut surface since it occludes many dentinal tubules with debris
- protective barrier
how strong is the smear layer
relatively weak and can be dissolved with acids
when do you not want to bond to the smear layer
when using total etch bonding systems
what are the products that do dentin bonding
- acid conditioners
- acidic primers
describe acid conditioners
- 35% phosphoric acid pH= 0
- most dentin bonding systems have acidic conditioners that remove the smear layer and aprtially demineralize the intertubular dentin
dentin without a smear layer provides good area for :
micromechanical retention
describe acidic primers
- HEMA
- pH = 2.5
- do not remove smear layer
- these self etch primers do not treat the dentin with 35% phosphoric acid before bonding
- they have a weaker bond, but have other advantages
when is the hybrid layer exposed
after the acid conditioners are applied and rinsed away
how is the hybrid layer formed
- a hydrophilic primer or wetting agent is applied to wet the dentin and prepare for easier penetration of the
- hydrophobic resin bonding agent that can adapt to the moist dentin and co-polymerize with the composite resin restoration
what does the bond strength of the hybrid layer develop from
resin penetrating and adapting to the demineralized intertubular dentin and exposed collagen fibers
what is another name for the hybrid layer
the resultant resin interdiffusion zone
how long do restorations relying solely on resin bonding to dentin last before being severely weakened
4 years
what primers offer weaker but longer lasting bond to dentin
self etch instead of total etch
when would self etch be useful
when margins are on dentin, and retention can be obtained mechanically with grooves or undercuts
what is the primary consideration when using self etch when margins are on dentin and retention can be obtained mechanically with grooves or undercuts
the longevity of seal rather than strength of bond
what etch is used in total etch AND self etch
35% phosphoric acid
adhesive bond strengths to superficial dentin are ______ than those for deep dentin
greater
deep dentin = ____ tubules
- more
- larger diameter
deep dentin = _____ amount of intertubular dentin in deep areas
reduced
an important aspect of dentin bonding agents is their ability to:
seal cut dentinal surfaces which reduced permeability and microleakage
deep dentin _____ permeable than superficial dentin
more
the defensive functions of the pulp are related to:
its reponse to irritation by mechanical, thermal, chemical, or bacterial stimuli
what does the deposition of reparative dentin by the replacement odontoblasts lining the pulp cavity act as
a protective barrier against caries and various other irritating factors
what is the process of formation of reparative dentin
- continuous but slow process
- takes 100 days to form a reparative dentin layer 0.12mm thick
why can inflammation of the pulp become irreversible and result in death
because the confined, rigid structure of the dentin limits the inflammatory response and the ability of the pulp to recover
how does the size of the pulp cavity change as we get older
gets smaller
younger pulps are more _____than older pulps
reparative
what is the contour of the pulp cavity
a miniature of the external surface of the tooth
a twinge of pain may be due to:
sugar, cold or acid from caries first contacting dentin
pain lasting a few seconds may be due to:
irritant continuously present or applied repeatedly
what does constant irritant cause
increased blood flow and volume (hyperemia) and inflammation of the pulp
what pain constitutes reversible pulpitis
pain that does not linger more than 10-15 seconds
what can reversible pulpitis pain be treated with
a restoration
what is the clinical interpretation of pain in irreversible pulpitis
- when pain is either spontaneous or lingers more than 15 seconds
- infection of pulp has occurred and resolution by operative dentistry treatment is not possible
- RCT is advised
what is the clinical interpretation of pain in pulpal necrosis
- when this irreversible pulpitis is untreated, pulpal necrosis follows
- spontaneous, continuous, throbbing pain
- pain elicited by heat that can be relieved by cold
- later with no response to any stimulus
- tooth may become sensitive to percussion
- RCT is needed
what is a primary objective during operative proceudres
- preserve the health of the pulp
- all caries must be removed except for indirect pulp cap
- avoid overheating the dentin
- all restorations must be well sealed
what tooth pains are not related to caries
- maxillary sinusitis
- cracked tooth
- occlusal trauma
how does maxillary sinus tooth pain manifest
- cold sensitivity
- spontaneous pain in maxillary posterior teeth
- hard to isolate single tooth
how does cracked tooth pain manifest
- cold sensitvity
- sudden unreproducible pain when chewing
how does pain from occlusal trauma manifest
- cold sensitivity or pain in chewing
- tooth movements when the teeth are clenched and moved side to side may be seen - called fremitis
describe cementum
- slightly softer than dentin and consists of about 45% - 50% inorganic material by weight, covers the apical root
- permeable to a variety of materials
- light yellow and slightly lighter in color than dentin, it has the highest fluoride content of all the mineralized tissue
when can dentin be exposed
when enamel and cementum do not meet in 10% of people
what do normal contours do
deflect food only to the extent that the passing food simulates the gingiva by gentle massage
what happens if curvatures of tooth contours are too great
- the tissues usually receive inadequate stimulation and a potential plaque trap is created
- food impaction producing perio disease, carious lesions, possible movement of teeth
where are the proximal contacts in all teeth
- located at the incisal third of the max and mand central incisors
- posteriorly the contact is at the junction of the occlusal and middle thirds which creates a larger occlusal embrasure
where should marginal ridge heights be and why
at the same height to prevent food impaction
what does contact positioned too far apically cause
food impaction
what are the periodontal concerns
- the level of gingival attachment and gingival sulus
- gingival health must be maintained by the teeth having correct form and position
- margin of the cavity prep should be ideally not positioned subG
- do not destroy attached keratinized tissue
what are the caries removal considerations
- caries on axial wall does not indicate cutting the entire axial wall toward the pulp- only remove caries
- caries on the pulpal floow may need widening of the prep to remove caries but dont deepen the entire pulpal floor - accept an irregular floor
what do you do if recurrent caries extends gingivally in the box area
have a box within a box rather than deepen the entire box gingivally unless caries require it
restoration should be supported by at least:
a tripod of natural structure
why should you not have the entire floor of restoration covered by CaOH
it is too soft to support the restoration
if the material is ahrd when set ( such as glass ionomer):
the entire pulpal floor can be covered material
