Apexification apeogenesis word2007 MTA mineral trioxide aggregate

1. Apexification
By
Ahmad Mostafa Hussein
Demonstrator, Department of Dental Biomaterials, B.D.S. (2004), Master (2012)
Faculty of Dentistry, Mansoura University
10/4/2012
Main points:
Introducton: * Apexogenesis: definition, the materials used.
* Apexification: definition, the materials used.
* Open apex: what is the treatment if reversible pulpitis?
and what is the treatment if irreversible pulpitis or necrotic pulp?
* Precautions during diagnosis.
Apexification
The factors most responsible for apical closure
Causes of failure
Ca(OH)2: 1)advantages, 2)disadvantages,
3)mechanism of mineralization induced by Ca(OH)2
MTA: 1)advantages, 2)disadvantages, 3)uses,
4)composition and compositional differences with Portland cement,
5)types of MTA and differences between gray MTA and white MTA.
6)reaction and formation of hydroxyapatite.
7) a)manipulation: * mixing
* insertion and ultrasonic vibration
* thickness
* X-ray
* moist cotton pellet
7) b) obturation and permanent restoration:
* gatta-percha.
* composite resin restoration extending below cervical level of the tooth.
Note: The post role in reinforcing the immature root remains unclear.
References
1

2. Introduction
Apexogenesis:
* Vital pulp therapy in an immature tooth to permit continued root growth and apical
closure.
* Depending on the extent of pulp damage, pulp capping or shallow or conventional
pulpotomy may be indicated.
* Materials: Ca(OH)2 (calcium hydroxide) or MTA (mineral trioxide aggregate).
MTA is the material of choice.
Apexification:
* Root-end closure. * It is the induction of a calcific barrier across an open apex.
* Materials: Ca(OH)2 (has serious disadvantages) or MTA.
MTA is the material of choice.
Open apex:
* Immature root, short root, thin walls, high risk of root fracture.
* Normally, apical closure occurs approximately 3 years after eruption.
* Treatment of reversible pulpitis: apexogenesis
Note: Shallow pulpotomy has higher success rate than conventional pulpotomy.
* Treatment of irreversible pulpitis or necrotic pulp:
- apexification (contraindication: very short roots and thin walls).
- root canal treatment & surgery (contraindication: very short roots and thin walls).
- extraction (if very poor prognosis).
2

3. Precautions during diagnosis:
* The apex appears more open when seen from the proximal. Conventional radiograph may
result in selection of inappropriate routine root canal treatment when apexogenesis or
apexification is indicated. Angled radiograph is helpful for diagnosis of open apex.
* Sometimes, it is difficult to differentiate between:
- normal radiolucency surrounding the immature open apex.
- pathologic radiolucency resulting from a necrotic pulp.
Comparison with the periapex of the contralateral tooth is helpful, with the other
diagnostic tests.
3

4. Apexification
* Root-end closure.
* It is the induction of a calcific barrier across an open apex.
* Apexification involves cleaning & shaping, followed by placement of Ca(OH)2 or MTA
to the apex.
* The factors most responsible for apical closure are thorough débridement & coronal seal.
* Causes of failure: bacterial contamination.
Ca(OH)2(calcium hydroxide)
Advantages: 1) alkaline pH, 2) bactericidal,
3) stimulate apical calcification.
Note: The reaction of periapical tissues to Ca(OH)2 is similar to that of pulp tissue.
Ca(OH)2 produces a multilayered sterile necrosis permitting subjacent mineralization.
Serious disadvantages:
1) long treatment period, usually takes 6-9 months, & may extend up to 21 months.
2) possible recontamination may occur.
3) weaken the root dentin & the risk of teeth fracture.
4) must be replaced at monthy intervals & removed some months after placement
before final obturation.
5) multiple visits by the patient.
Mechanism of mineralization induced by Ca(OH)2:
* Calcium ions dissociated from Ca(OH)2 are critical for inducing the mineralization of
osteoblasts.
* Hydroxyl ions did not have any effect on the mineralization.
* The mineralization activity of Ca(OH)2 was higher at pH 7.4 than at pH 8.5. Mineralization
activity was higher under neutral conditions.
4

5. MTA (mineral trioxide aggregate)
1. Advantages:
1) High success rate. It is the material of choice for apexification & apexogenesis.
2) Excellent biocompatibility.
3) Excellent sealing ability.
4) Save treatment time.
5) More radiopaque than Ca(OH)2.
6) Alkaline pH, which may impart antibacterial effect on some facultative bacteria.
7) Produces an artificial barrier, against which an obturating material can be
condensed.
8) Hardens (sets) in the presence of moisture.
9) Can induce formation (regeneration) of dentin, cementum, bone & periodontal
ligament.
10) Appropriate mechanical properties.
11) Vasoconstrictive. This could be beneficial for hemostasis (most importantly in
pulp capping).
2. Disadvantages:
1) Long setting time (2-4 h after mixing).
2) Poor handling properties. The loose sandy nature of the mixture causes much
difficulty for the insertion & packing of MTA.
3) High cost.
3. Uses:
1) Apexogenesis, direct pulp capping and pulpotomy.
2) Apexification, and root-end filling.
3) Repair of root perforations.
4) Repair of internal and external resorption.
5

6. 4.1. Composition:
* MTA is mainly composed of 3 powder ingredients, which are 75% Portland cement,
20% bismuth oxide, 5% gypsum; lime (CaO), silica (SiO2) & bismuth oxide (Bi2O3) are
the 3 main oxides in the cement.
* Portland cement is the major constituent. It is responsible for the setting & biologic
properties.
* Bismuth oxide provides radiopacity.
* Gypsum is an important determinant of setting time.
* Portland cement is composed of 4 major components; tricalcium silicate, dicalcium silicate,
tricalcium aluminate, & tetracalcium aluminoferrite.
* Tricalcium silicate is the most important constituent of Portland cement. It is the major
component in the formation of calcium silicate hydrate which gives early strength to
Portland cement.
* Dicalcium silicate hydrates more slowly than tricalcium silicate & is responsiple for
the latter’s strength.
* Aluminoferrite (contains iron) is present in gray MTA. It is responsible for
the gray discoloration. It may discolor the tooth.
6

7. 4.2. Compositional differences between MTA & Portland cement:
MTA Portland cement
1. Less amount of gypsum (approximately 1.
half that in Portland cement) which leads
to longer setting time.
2. No toxic impurities 2. May contain toxic impurities.
3. Higher compressive strength & 3.
microhardness values.
4. Less soluble. 4.
5. More radiopaque. 5.
6. 6. Not have US Fedral approval for clinical
purposes.
7

8. 5. Types of MTA: Gray MTA & White MTA.
* MTA was first described in the dental literature in 1993. When it was first commercialized,
it had a gray discoloration (gray MTA). In 2002, white MTA was introduced.
Gray MTA (GMTA) White MTA (WMTA)
1. Contains aluminoferrite (contains iron), 1. Tooth-colored, due to lower amounts of
which is responsible for the gray Fe2O3.
discoloration. It discolors both the tooth &
gingival tissue close to the repaired root
surface.
2. 2. Smaller particles with narrower size
distribution (8 times smaller than that of
GMTA).
3. 3. Greater compressive strength.
4. 1. Produces 43% more surface 4.1.
hydroxyapatite crystals than WMTA in
an environment with PBS (phosphate-
buffered saline).
4.2. Induced dentin formation more 4.2.
efficiently; high number of dentin bridge
formation (reparative dentin).
5. Increase in acidity or alkalinity beyond 8.4 can deleteriously affect the surface hardness of
set MTA.
8

9. 6. Reaction & formation of hydroxyapatite:
* Hydration reaction.
* Note: - MTA is called hydraulic silicate cement (HSC).
- It is called hydraulic cement ( ) (i.e. sets & is stable under water)
relying primarily on hydration reactions for setting.
- The material consists primarily of calcium silicate.
* When mixed with water, MTA sets. The pH of MTA increases from 10 to 12.5 three hours
after mixing. In high pH environment, the calcium ions that are released from MTA react
with phosphates in the tissue fluid to form hydroxyapatite (the principal mineral in teeth
& bones).
7.1. Manipulation , 7.2. Obturation & permanent restoration:
1. Mixing: gray MTA & white MTA are mixed with supplied sterile water in a powder to
liquid ratio of 3:1 according to the manufacturer’s instruction.
Note: Poor handling properties. The loose sandy nature of the mixture causes
much difficulty for the insertion & packing of MTA.
2. Insertion: Ultrasonic-assisted condensation [the ultrasonic vibration applied to endodontic
plugger(condenser)] is more efficient than hand condensation in:
- the apical flowing of MTA (enable better flow).
- delaying bacterial leakage (enable better adaptation).
- the production of denser MTA apical plug.
3. Thickness: 5-mm MTA apical plug provided better reduction of bacterial leakage (better
microleakage resistance).
9

10. 4. A Radiogragh is made.
5. A moist (wet) cotton pellet is placed above the MTA (to ensure setting), & a well-sealing
temporary restoration is placed. Note: MTA sets 3-4 h after mixing.
6. 1.The patient is recalled when MTA has set (at least 24 hours) for obturation & placement
of permanent restoration.
Note: technique for apical barrier detection: based on the tactile sensation felt by the
operator to detect an apical stop. Radiograghs is an adjunct to the clinical
technique.
6.2. Complete the root canal treatment with gatta-percha & composite resin restoration
extending below the cervical level of the tooth to strengthen the root’s resistance to fracture.
Notes
* If a root canal is fully obturated with MTA, re-entry to create space for a post can be very
difficult using just ultrasonic or rotary nickel-titanium instruments, presumably
due to its hardness & strength.
(i.e. root canal obturation with MTA would severely limit retreatment options).
* Composite resin or MTA materials in the root canal may make future endodontic
retreatment difficult, while titanium, ceramic & zirconium posts are problematic to
retrieve .
* If a post is to be used, a long thin fibre post should be chosen to reduce the stresses that
cause tooth fracture.
* Superior retention of posts has been observed with dual cure resin luting cements.
* The role of posts & luting agents in reinforcing root filled immature anterior teeth
remains unclear.
10

11. References
1. Torabinejad M, Walton RE. Endodontics Principles And Practice. 4 th ed. Saunders Co.;
2009. p. 29–34.
2. Ingle JI, Bakland LK, Baumgartner JC. Ingle’s Endodontics 6. 6 th ed. Hamilton, Ontario,
Canada: BC Decker Inc.; 2008. p. 1383–99.
3. Asgary S, Ehsani S. MTA resorption and periradicular healing in an open-apex incisor:
a case report. Saudi Dent J 2012; 24: 55–9.
4. Cardoso-Silva C, Barberίa E, Maroto M, Garcίa-Godoy F. Clinical study of mineral
trioxide aggregate in primary molars. Comparison between gray and white MTA–a long
term follow-up (84 months). J Dent 2011; 39: 187–93.
5. Darvell BW, Wu RCT. ‘‘MTA’’–An hydraulic silicate cement: review update and setting
reaction. Dent mater 2011; 27: 407–22.
6. Chala S, Abouqal R, Rida S. Apexification of immature teeth with calcium hydroxide or
mineral trioxide aggregate: systemic review and meta-analysis. Oral Surg Oral Med
Oral Pathol Oral Radiol Endod 2011; 112: e36–e42.
7. Narita H, Itoh S, Imazato S, Yoshitake F, Ebisu S. An explanation of the mineralization
mechanism in osteoblasts induced by calcium hydroxide. Acta Biomaterialia 2010; 6:
586–90.
8. Wang WH, Wang CY, Shyu YC, Liu CM, Lin FH, Lin CP. Compositional characteristics
and hydration behavior of mineral trioxide aggregates. J Dent Sci 2010; 5(2): 53–9.
9. Kim US, Shin SJ, Chang SW, Yoo HM, Oh TS, Park DS. In vitro evaluation of bacterial
leakage resistance of an ultrasonically placed mineral trioxide aggregate orthograde
apical plug in teeth with wide open apexes: a preliminary study. Oral Surg Oral Med
Oral Pathol Oral Radiol Endod 2009; 107: e52–e6.
10. Desai S, Chandler N. The restoration of permanent immature anterior teeth, root filled
using MTA: a review. J Dent 2009; 37: 652–7.
11. Zhu WH, Pan J, Yong W, Zhao XY, Wang SM. Endodontic treatment with MTA of a
mandibular first premolar with open apex: case report. Oral Surg Oral Med Oral Pathol
Oral Radiol Endod 2008; 106: e73–e5.
12. Roberts HW, Toth JM, Berzins DW, Charlton DG. Mineral trioxide aggregate material
use in endodontic treatment: a review of the literature. Dent Mater 2008; 24: 149–64.
11