During tooth development, the inner and outer dental
epithelia fuse and form the cervical loop, which results in Hertwig’s
epithelial tooth sheath, a structure responsible for root formation.1
The presence of healthy pulp is essential for root development and apical
closure. An injury sustained between the ages of 6 and 14 can adversely affect
a patient’s pulpal health and interrupt or arrest root development.2
When the pulp is vital and the apex is not fully formed, it is imperative to
maintain pulp vitality for dentin formation.3 Apexogenesis, which
allows continued root formation and normal apical closure, is generally the
optimal treatment for traumatized immature teeth with vital pulps. The severity
of the injury influences the vitality of the pulp, which can be maintained by
either direct pulp capping or pulpotomy. Successful treatment, however, is
dependent on the extent of pulpal damage and the potential of restoring the
involved tooth.4 Materials that have traditionally been used for
pulp capping or pulpotomy include calcium hydroxide,5 osteogenic
protein-1,6 dentin bonding agents,7 and mineral trioxide
When a severely inflamed or necrotic pulp in a tooth with an
immature apex requires removal, root canal therapy is difficult to accomplish
due to the presence of thin, fragile walls and the open apex.9 In
these instances, apexification (root-end closure) is generally the preferred
treatment. This procedure involves removal of the inflamed or necrotic pulp
from the root canal, asepsis of the system, and provision of an environment for
closure of the apical foramen. It has been suggested that control of the
infection enables the apical development in nonvital teeth to be resumed.10
Numerous materials have been recommended to enhance apexification, including
Tricresol and Formalin,11 antibiotic pastes,12 tricalcium
phosphate,13 collagen-calcium phosphate gel,14 calcium
hydroxide in various mixes,9,15 as well as growth factors and bone
morphogenic proteins.16,17 One widespread treatment for immature
teeth with severely inflamed or necrotic pulps is apexification utilizing
calcium hydroxide as an intracanal medication. The inherent disadvantages of
this technique are the necessity of multiple visits over an extended period,
the unpredictability of treatment results, and the reliance on patient
compliance. An alternative to apexification requires the placement of an apical
barrier to prevent the extrusion of filling materials during obturation.
Various materials (ie, tricalcium phosphate,18 dentin chips,19,20
calcium hydroxide powder,21 and MTA17) have been utilized for this
The MTA material is characterized by its favorable sealing
ability and biocompatibility. It has demonstrated significantly less dye and
bacterial leakage when compared to investigations of amalgam, IRM, and Super
EBA.22,23 In 1996, Ford et al also reported the use of MTA as a
pulp-capping material.8 In a recent canine study, Shabahang et al
demonstrated that apical hard tissue formation with MTA was significantly more
predictable than calcium hydroxide or osteogenic protein-1.17
Mineral trioxide aggregate has also been successfully used for the repair of
lateral24 as well as furcal perforations,25 and has been
observed to stimulate cytokine production in human osteoblasts.26
The following three case presentations demonstrate the use of MTA in vital pulp
therapy (ie, apexogenesis) and the formation of an apical barrier in permanent teeth with open apices.
An 8-year-old girl presented with a fracture of tooth
#8(11). The patient suffered a traumatic injury 6 days previously and was
referred for endodontic evaluation. The patient’s medical history was
noncontributory and no known drug allergies were noted. Although the patient
experienced sensitivity during biting, the trauma caused no further discomfort
or pain. The exposure of the pulp horn was revealed by clinical examination
under 310 magnification with a surgical microscope and probing with a size 50
(ISO) endodontic file, and the presence of an open apex was confirmed via
radiographic evaluation (Figure 1A). These examinations and an elevated,
nonlingering response to cold indicated the presence of reversible pulpitis in
the tooth, which had normal periradicular tissues. It was determined that a
shallow pulpotomy would enable further root development.
Under local anesthesia (2% lidocaine with 1:100,000
epinephrine) and rubber dam isolation, an access cavity was prepared and the
coronal 2 mm of the pulpal tissue was removed using a sharp, round diamond bur
in a high-speed handpiece under copious water irrigation. Following irrigation
with sodium hypochlorite (NaOCl), the surface of the exposed pulp was
disinfected for 5 minutes using a cotton pellet saturated with 5.25% NaOCl. A
thick mixture of MTA was placed over the exposed pulp and subsequently covered
with a moist cotton pellet to ensure the complete setting of the material
(Figure 1B). The access cavity was then restored with a provisional sealing
The initial healing of the site was evaluated 2 weeks
postoperatively, at which time no sensitivity to percussion or palpation was
noted on the maxillary incisors. Utilizing a direct composite resin procedure,
the tooth was restored by the patient’s general practitioner. At the 6-month
recall evaluation, no complications were evident in the treated site, and all
teeth were within normal testing limits.
Eight months postoperatively, the patient experienced pain
associated with tooth #9(21). Following thermal testing, the tooth was
diagnosed with reversible pulpitis, and a shallow pulpotomy was performed using
MTA. The existing composite restoration — placed to restore the fractured
incisal edge following injury — was removed, and access was gained into the
pulp chamber. At the time of initial injury, this tooth responded within normal
limits to thermal testing as well as percussion and palpation. Using a sterile
diamond bur, 2 mm of pulpal tissue was removed; bleeding was controlled by
irrigation with 5.25% NaOCl and direct pressure, which was applied with cotton
pellets. A thick barrier of MTA was placed over the exposure site, and a wet
pellet was placed over the material. The access cavity was provisionally
restored as aforementioned.
Two weeks following the second pulpotomy, the teeth
responded within normal limits to pulp testing. Upon 3-month reevaluation, no
sensitivity to percussion or palpation was determined. Each incisor responded
to electric pulp testing, and no periodontal pocket measurements greater than 3
mm were noted (Figure 2A). At 1 year, all teeth continued to be free of
symptoms and responded to pulp vitality testing. Radiographic examination
demonstrated continued root development with closure of the apical foramen in
both central incisors (Figure 2B). Apical closure and normal periapical tissues
were evident in the 2-year postoperative radiograph of the site (Figure 3). At
this interval, the teeth demonstrated normal responses to thermal and electric
pulp testing, and no palpation or percussion sensitivity was observed.
A 10-year-old boy presented for treatment of an anterior
tooth 1 month following dental trauma. Clinical evaluation revealed an incisal
edge fracture of tooth #8(11). Furthermore, an intraoral swelling and a sinus
tract stoma were noted superior to this central incisor. Radiographic
examination demonstrated the presence of a partially developed root and a
periapical radiolucent lesion that was associated with the maxillary right
central incisor (Figure 4). Pulp testing was performed, and all teeth — except
tooth #8(21)—responded to thermal testing. The maxillary right central incisor
was diagnosed as necrotic with a chronic periradicular abscess. The available
treatment options were discussed with the patient and his parents, and root
canal therapy using MTA as an apical barrier was selected.
Under local anesthesia (2% lidocaine with 1:100,000
epinephrine) and rubber dam isolation, the necrotic tissues were removed, and
the canal was thoroughly debrided and irrigated with 5.25% NaOCl. A thick
mixture of calcium hydroxide powder and sterile saline was placed in the canal
as an intracanal dressing and maintained for 3 weeks. During the subsequent
appointment, the canal was rinsed with NaOCl to remove the calcium hydroxide,
dried, and a 3 mm apical plug of MTA was placed using a small carrier and
pluggers (Figure 5). A moist cotton pellet was placed over the MTA and the
access cavity was sealed with provisional filling material. One month following
this procedure, the cotton pellet was removed and the remainder of the canal
was obturated with warm gutta-percha and sealer. The definitive composite resin
restoration was placed to seal the access cavity using a direct technique
(Figure 6A). Upon reevaluation 6 months postoperatively, no sensitivity was
noted to percussion or palpation. The sinus tract over the right central
incisor had healed completely, and the periodontal pocket depths measured 3 mm
or less. Radiographic evaluation demonstrated the complete healing of the
periapical lesion and the formation of a band of hard tissue that surrounded
the MTA plug (Figure 6B).
An 8-year-old boy presented for treatment following a
luxation injury to the maxillary left central incisor. In order to achieve
stabilization, the tooth was splinted for a 2-week period. The patient was recalled
after 4 months, at which time the presence of ankylosis was noted (Figure 7).
During the 2-year recall appointment, clinical and radiographic examinations
revealed the infraocclusion of the maxillary left central incisor and
radiographic indications of replacement resorption (Figures 8 and 9). Further
evaluation demonstrated the presence of a supernumerary lateral incisor between
teeth #6(13) and #7(12). The maxillary central incisor was extracted and the
supernumerary tooth was transplanted into this site and stabilized in the arch
(Figure 10). Due to the presence of an incompletely developed root apex,
endodontic therapy was not initiated in the weeks following transplantation in
order to facilitate the possibility of revascularization. Three months
postoperatively, the gingival tissues had healed and exhibited minimal
indications of marginal adaptation or healing.
During the 18-month recall, pulp testing elicited no
response from the transplanted tooth, which had developed a periradicular
lesion (Figure 11A). A necrotic pulp and chronic periradicular periodontitis
were diagnosed in the tooth. Due to the necrosis of the pulp prior to the
completion of root development, an open apex that required attention prior to
completion of endodontic therapy was present. The root canal system was
chemomechanically debrided with K-type endodontic files and 5.25% NaOCl to
remove necrotic tissues, the canal was medicated with a thick paste of calcium
hydroxide, and the access cavity was sealed with a provisional filling
material. An apical barrier was placed 7 days postoperatively. The calcium
hydroxide paste was removed with 5.25% NaOCl and the canal was dried. A thick
layer of MTA was placed in the apical 3 mm of the root and allowed to set for 1
week in the presence of moisture provided coronally by a moist cotton pellet.
The remainder of the canal was subsequently obturated with warm gutta-percha
and sealer (Figure 11B), and a composite resin restoration was placed in the
access cavity. One year postoperatively, a thick layer of calcific tissue
formed apical to the MTA barrier, and the periradicular tissues had healed
(Figure 12). Clinical examination revealed normal soft tissue architecture with
no indications or symptoms of periradicular pathosis. Two years following
treatment, the additional thickening of the apical hard tissue barrier and
healthy periradicular tissues were evident radiographically (Figure 13).
(Continued from page 1 )
The prevention of bacterial leakage is a critical factor in
the healing of the pulpal and periapical tissues.27 While MTA can be
used for vital pulp therapy, the success of this treatment is based on the
removal of all carious dentin and residual bacteria with a NaOCl solution.
Previous investigations of the traumatically exposed pulp have indicated that infection and inflammation do not extend
beyond 2 mm during the initial 2 weeks postinjury.5 Further
recontamination of the pulp was prevented by the placement of MTA, which has
been demonstrated to provide an adequate seal.22,23 Mineral trioxide
aggregate may offer an advantage over calcium hydroxide for pulp capping and has been demonstrated to provide an adequate seal.22,23
Mineral trioxide aggregate may offer an advantage over calcium hydroxide for
pulp capping and pulpotomy due to its superior sealing ability,
biocompatibility, and reduced solubility. It is essential to note that in the
presence of moisture, MTA sets in approximately 3 hours.28 Its
compressive strength, however, appears comparable to that of provisional
filling materials, which renders MTA unsuitable as a permanent restorative
material.28 Therefore, it is necessary to complete pulp capping and
pulpotomy procedures in two appointments. When the entire cavity preparation is
restored with MTA during the initial visit, it is imperative that the patient
refrains from eating or drinking for a period of three hours until the MTA has
Mineral trioxide aggregate can also be utilized to perform
apexification; the principles of this procedure are similar to those of pulp capping
and pulpotomy. Hence, it is necessary to remove the bacteria and their
by-products from the canal using irrigation with sodium hypochlorite and
intracanal medication with calcium hydroxide for a minimum of one week; the
latter has been demonstrated to eliminate bacteria in the root canal when
applied for this period.29 In addition, MTA permits an adequate seal
of the canal to be maintained and prevents bacterial leakage and interaction
with the periradicular tissues. Mineral trioxide aggregate is easily
manipulated to the apical extent of the canal, and in instances where the
material is slightly extruded beyond the confines of the root apex, cementum
will form around it.17
The MTA material has numerous applications in endodontic
therapy that range from apexification to pulpotomy. The primary advantages of
this material as an apical barrier include a reduction in the number of
appointments required to complete the treatment, the development of a proper
apical seal, and the ability to induce a deposition of hard tissue. This
article has demonstrated a series of clinical procedures that utilize MTA to
facilitate apexification in the vital roots of permanent teeth and has
highlighted the importance of protecting the dental structures from bacterial
inflammation and contamination. Although additional research is necessary to
determine additional indications for MTA, its use in endodontics certainly
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