Introduction to Endodontics Forth Year

1. RESTORATION OF ENDODONTICALLY
TREATED TEETH

2. Effect of endodontic treatment on the tooth/teeth:
The major changes in the endodontically treated teeth include:
• loss of tooth structure
• altered physical characteristics (functional loss)
• altered esthetic characteristics of the residual tooth

3. 1. Loss of tooth structure:

The loss of tooth structure is always not a direct result of endodontic
treatment

In most cases it is the previous episode of caries, fracture, tooth
preparation, restorations.

Gutmann (1992) showed that endodontic access into the pulp chamber
destroys the structural integrity of the coronal dentin→ greater flexing
of the tooth under occlucsal loading

4. 2. Altered physical characteristics:
 Several studies have proposed that the dentin in endodontically treated teeth is
substantially different than dentin in teeth with “vital” pulps
 It was thought that the dentin in endodontically treated teeth was more brittle because
of water loss and loss of collagen cross-linking.
 Huang et al. (1991) compared the physical and mechanical properties of dentin
specimens from teeth with and without endodontic treatment at different levels of
hydration.
 They concluded that neither dehydration nor endodontic treatment caused
degradation of the physical or mechanical properties of dentin

5.  Thus it is the loss of structural integrity that plays a major role in fracture
of endodontically treated teeth.
 Access preparations result in increased cuspal deflection during function
and increase the possibility of cusp fracture and microleakage at the
margins of restorations. ( Panitvisai P, Messer HH. 1995)

6.  Randow and Glantz (1992) reported that teeth have a protective
feedback mechanism that is lost when the pulp is removed, which
also may contribute to tooth fracture

7. 3. Altered aesthetic characteristics:
 Biochemically modified dentine modifies light refraction through the tooth and
modifies its appearance
 Improper endodontic cleaning and shaping of the coronal area contribute to
discoloration by degradation of vital tissues left in the pulp chamber.
 Medicaments and restorative materials used during the treatment

9. General considerations in the restoration of endodontically treated teeth:

Root-treated teeth are in a vulnerable state until they are permanently restored.

The risks they face fall into two major categories:

Fracture of remaining tooth tissue

Reinfection of the root canal from the mouth
.

11. 
Irrespective of type of restoration chosen for placement in a root
canal treated tooth, it is important to carry out a thorough preoperative clinical and radiographic assessment

12. Biological considerations:
 Moisture content of remaining dentine?
•
0 → 9% less moisture in endodontically treated teeth
•
Certain sealer cements may also affect the physical properties of root
canal treated teeth. It has been shown that the eugenol, Glass ionomer
etc., increases dentine microhardness.
•
Weakened collagen intermolecular cross-links of Dentine  lower shear
strength, decrease in tensile strength and an increase in brittleness

13. Restoration of root-filled teeth - pre-treatment assessment:

The benefits of root canal treatment or re-treatment and the placement of an indirect
restoration, both of which are time-consuming and expensive procedures, must be
weighed against extraction of the tooth.

Teeth with hopeless prognosis→ extraction

Medically compromised individual→ endodontic intervention despite guarded
prognosis

14. Endodontic evaluation:
 Clinical endodontic tests should determine the condition of the supporting structures
with regards to the presence of inflammation of the periodontal ligament and
surrounding peri-radicular tissues.
 A positive test → persistent or new pathology→ further treatment prior to placement
of the definitive restoration

15. Following endodontic clinical tests should be carried out as part of the pre-operative
assessment:
1. Percussion:

Tenderness to percussion indicates the presence of periradicular
inflammation

Negative test does not rule out the presence of inflammation and a positive
result may also be because of periodontal disease.

Teeth with a chronic periradicular periodontitis often give a negative
response to percussion testing.

16. 2. Palpation :

Palpation of the mucosa overlying the apex of a tooth will be tender if inflammation
has reached the mucoperiosteum.

fluctuation, hardness or crepitus
3. Presence of a sinus tract

The presence of a sinus indicates remaining infection within the root canal system

Tract may epithelialise if it has been present for a long time, however this will heal
without further treatment on successful resolution of the periapical inflammation

17.  Opening can be far from the involved tooth or drainage occurs through the
periodontal ligament→ place a fine gutta-percha cone into a sinus tract
and take a radiograph to confirm the source of the infection rather than
relying on the location of the sinus tract opening

18. 4. Mobility

The presence of tooth mobility may suggest the loss of connective tissue
attachment and inflammation of the periodontal ligament that can be of pulpal
or periodontal origin.

?? → root fracture / trauma [occlusal trauma]

It is not only important to look at the degree of tooth movement, but also the
fulcrum about which the movement takes place. Also gives valuable
information.

A fulcrum of movement more coronal to the apical third of the root → root
fracture

19. Periodontal evaluation.

Maintenance of periodontal health is important for the long term success of
endodontics

Prognosis of a tooth → satisfactory root canal and restorative treatment→ existing
periodontal condition

It is important that combined perio-endo lesions are correctly diagnosed to ensure that
the patient receives the correct treatment

20. Treatment planning for non-vital teeth
1.
Pretreatment Evaluation:
i.
Quality of the endodontic
treatment
ii.
Periodontal condition
iii.
Restorative evaluation
•
Anatomic position of the tooth
•
The amount of remaining
coronal tooth structure
•
iv.
The functional load on the tooth
esthetic evaluation
2.
Treatment plan:
i.
ii.
iii.
Post
Core
Definitive restoration

21. Factors to be considered for treatment planning are:
 amount of remaining tooth structure
 anatomic position of the teeth
 functional load on the tooth
 aesthetic requirements for the tooth

22. 1. Amount of remaining tooth structure:
 There is a direct relationship between the amount of remaining tooth structure
and the ability of a tooth to resist occlusal forces
 As the remaining tooth tissue decreases the possibility of fracture increases

23. 2. Anatomic position of the tooth:
As anterior teeth are inclined at an angle to the occlusal plane, the forces of
occlusion are not directed along their long axis, making them more susceptible to
fracture

24. 
Posterior teeth carry greater occlusal loads → require greater protection against
possible fracture. Minimal occlusal access preparations in otherwise intact teeth may
be restored conservatively using composite resin which has been shown to improve
tooth stiffness
 Wherever possible posts should be avoided in posterior teeth as the roots are often
narrow and/or curved and post space preparation can lead to a strip or lateral
perforation.

26.  Sufficient tooth structure and / pulp chamber→ retention

28. 3. Functional loading on the teeth/ tooth:
 Root-filled teeth that show signs of tooth wear, primarily as a result of
attrition, possible bruxism and/or heavy occlusal loads especially in a lateral
direction require a stronger foundation.
 Such teeth should be preferably restored with a full coverage crown.
 Abutment teeth prepared for fixed or removable restorations undergo greater
horizontal and torquing forces and therefore require more extensive protection
and retentive features

29. 4. Aesthetic requirements of the teeth/tooth:
 Anterior teeth and the maxillary first pre-molars inhabit the aesthetic zone.
 Alterations to the color or translucency→ negative
impact on the aesthetics.

30.  Restoration of endodontically treated teeth is of utmost importance to the success of the
endodontic treatment.
 This brings the restored tooth/ teeth as close to the normal tooth in terms of physiological,
functional and morphological demands.
 Restoration of the endodontically treated teeth serve two most important functions.
1.
Prevent recontamination of the root canal space and the peri-apex.
2.
Replace the lost coronal structure and reinforce the strength of remaining tooth
structure

31. RESTORATION OF TEETH WITH MINIMAL LOSS OF CORONAL TOOTH
STRUCTURE
 The treatment protocol for teeth with minimal loss of tooth structure depends to a great
extent on the presence of existing restorations.
 Access openings are made through a number of different restorative materials→ gold
alloys, base metal alloys and porcelain, as well as enamel and dentin.
 Bonding to each of these substrates presents us with specific challenges.

32. Influence of temporary/provisional restorations on the final restorations
(adhesive restorations):
 One of the most common materials used is zinc oxide –eugenol.
 Studies have proved that residual eugenol → deleterious effect on the physical
properties of composite resin restorations→ surface roughness, micro hardness and
colour stability.
 Neither IRM or CAVIT interfered with dentin or enamel bonding

33.  Many of the temporary cements whether they contain eugenol or not, leave behind
an oily layer of debris that must be removed before bonding.
 Acid etching demineralizes the dentin surface to a depth of 5 μm and removes the
eugenol rich layer.
 An „etch and rinse‟adhesive system should be used instead of self-etch systems,
which incorporate the eugenol rich smear layer into the hybrid layer.

34. Sodium hypochlorite:
 Studies have shown that dentin that has been exposed to sodium hypochlorite
exhibits resin bond strengths that are significantly lower than untreated dentin [Bond
strength as low as 8.5 MPa.] (normal 11-24 MPa)
 Sodium hypochlorite is an oxidizing agent and leaves behind an oxygen rich layer on
the dentin surface. Oxygen has been shown to inhibit polymerization.
 It has been showed that application of 10% ascorbic acid or 10% sodium ascorbate
( reducing agents), reversed the effects of NaOCl.

35. MATERIALS COMMONLY USED:
Silver amalgam alloy:
 One of the most common and popular choice in restoring the access cavities.
 A „bonded amalgam‟ restoration is often recommended in which a resin adhesive [(4META)-based systems]* is placed on a cavity walls before condensation of amalgam
 When amalgam is used without an adhesive, it leaks initially but „self heals‟ with time
as corrosion products form at the amalgam and tooth interface.
 The seal produced may be more durable than resin
 Ad-mixture alloys have slight setting expansion which tends to reduce the micro
leakage ,where as spherical alloys shrink slightly while setting
*4-methyloxy ethyl trimellitic anhydride

37. Glass ionomer cements:
 Only restorative materials, that depend primarily on a chemical bond to the tooth
structure.
 They form an ionic bond to the hydroxyapatite at dentin surface and also obtain
mechanical retention from microporosities in the hydroxyapatite.
 Other advantages are
→ low polymerization shrinkage,
co-efficient of thermal expansion = dentin,
fluoride release,
anti-microbial.
[Type VI GIC - Core build up ]

38. Clinical procedure for restoring the access with a composite resin:
1. Remove the excess of sealer and the gutta-percha material from the chamber until
the the gutta-percha is seen only at the orifices.
2. Counter sink the orifices with a small round bur i.e the orifices are cleared off the
GP to a depth of around 1 to 2 mm.
3. Treat the dentin and enamel ,if present, with 30% to 40% phosphoric acid for 15s.
4. Thoroughly rinse and dry the dentin [then re-wet with a moist sponge.]
5. Apply the primer and adhesive
6. Bulk fill with a glass ionomer or dual cure or self cure composite to within 2 to 3
mm of the cavo surface and light cure.

39. 7. Place the first increment of light cure composite. The first increment should
include the longest vertical wall and taper to the base of the the opposing
vertical wall.
8. Light cure for 40s
9. Fill the remaining space with the second increment and light cure.
10. Contour and adjust the occlusion
11. Finish and polish the restoration

43. Post Endodontic restoration of Restoration of discolored teeth:

48. Complications of bleaching: external resorption