Update on Apexogenesis: Case Reports: Achieving Predictable Root Maturation in Young Patients

INTRODUCTION
Dental implants are now considered the hallmark procedure if a tooth cannot be saved. However, implants cannot be used predictably in young children, since they can only be placed after the jaw has finished growing. If a dental implant is placed before a child’s jaw growth is complete, then it may impede jaw growth and stop other teeth from moving into their natural positions.
What do you do if a child has deep decay into the pulp, or trauma with a pulp exposure and with an open apex? Obviously, an extraction and an implant will not be an acceptable treatment. The answer is to keep the pulp alive! Keeping the pulp alive will allow thickening of the dentinal wall to occur, bring more strength to the root, allow the bone more time to mature, and will also allow the crown-to-root ratio to improve. If the patient were to ever lose the tooth as an adult, an implant would be a viable option due to bone maturation and jaw stabilization.
This article will discuss the apexogenesis procedure, presenting 3 clinical case examples.

Apexogenesis
Most dentists and specialists agree that vital pulp therapy is the treatment of choice for immature teeth (incompletely developed apices).¹ One of the most current techniques to be able to achieve this goal predictably is using a technique called apexogenesis. Apexogenesis is defined as a vital pulp therapy of an immature tooth that permits continued root formation and apical closure.² In the past, there have been 2 major agents used over the years to achieve apexogenesis. One is calcium hydroxide USP (CaOH) and the other is called mineral trioxide aggregate (MTA).
Calcium Hydroxide Powder (Sultan Dental) (Figure 1a) has been a popular pulpotomy agent for this type of vital pulp therapy and it is still widely used clinically around the world. It was introduced by Hermann³ in 1936 as a type of biological dressing for the pulp. Because of its alkalinity (pH of 12), it is so caustic that when placed in contact with vital pulp tissue, the reaction produces a superficial necrosis of the pulp.⁴ In addition, CaOH is known to wash out over time in both powder/paste or liner forms. Therefore, the search continued for procedures and materials that are more biocompatible while stimulating continued dentin formation and apical closure of immature teeth without washing out so readily.
Mineral trioxide aggregate (Pro Root MTA [DENTSPLY Tulsa Dental Specialties]) (Figure 1b), is in the author’s opinion, an endodontist’s “miracle material” because it can be used for various procedures such as perforation repair, apexification, retrofill material for apicoectomy, revascularization, and apexogenesis. It is also currently being used as the vital pulp therapy material of choice, and has been shown to provide an enhanced nonresorbable seal over the pulp.⁵ Mineral trioxide aggregate was used experimentally for a number of years, and was approved for human use by the FDA in 1998.6
Mineral trioxide aggregate is a powder consisting of tricalcium silicate, dicalcium silicate, tricalcium aluminate, calcium sulfate dehydrate, and bismuth oxide.⁷ When the material is hydrated, it becomes a colloidal gel that solidifies in approximately 3 hours.⁶ It is available in one-gram packets of MTA powder (both white and gray in color) and costs approximately $300 for a box containing 5 packets.
Mineral trioxide aggregate has been shown to have superior sealing ability compared to amalgam, zinc oxide eugenol, or intermediate restorative material (IRM).8 Mineral trioxide aggregate used as a direct pulp capping material stimulates natural dentin repair at pulpal exposure sites.⁹ It was also found to produce less inflammation and better dentin bridge formation, when compared with CaOH in monkeys.⁸ In addition, MTA was found to be biocompatible when implanted into guinea pigs, dogs, and monkeys, and was more biocompatible than amalgam, super ethoxy benzoic acid, and immediate restorative material.¹⁰ In animal studies, MTA was the only material that allowed cementum overgrowth and attachment of the Sharpey’s fibers from the periodontal ligament.¹⁰ Furthermore, the setting ability of MTA is uninhibited by blood or water.¹¹ The hydrophilic nature of MTA makes it a great material to use for pulp capping.

CASE REPORTS
Case 1
Diagnosis and Treatment Planning—A 7-year-old female patient presented with deep and extensive decay in her right permanent first molar (tooth No. 30) (Figure 2a). The tooth was asymptomatic and there was no sign of swelling or lymphadenopathy. There was no sinus tract noted and the tooth was not mobile. Probing depths were 2 to 3 mm. In addition, the tooth exhibited no percussion sensitivity and the cold test (Hygienic Endo Ice [Coltène]) revealed that the pulp was vital. Radiographically, there was extensive decay that appeared to encroach on the pulp. The mesial and distal roots were immature with open apices; and the patient had deciduous and permanent teeth present, with succedaneous teeth forming in the mandible. The diagnosis was asymptomatic irreversible pulpitis with normal immature apicies.

Figure 1a. Calcium Hydroxide Powder (Sultan Dental).	Figure 1b. Mineral trioxide aggregate (White) (Pro Root MTA [DENT­SPLY Tulsa Dental specialties]).

Clinical Treatment (Apexogenesis Procedure)—Informed consent was obtained for treatment. Two carpules of xylocaine 2% (1:100,000 epinephrine) were administered via an inferior alveolar nerve block. A medium green latex rubber dam (Safe Touch Dental Dam [Medicom]) was applied, and the decay was excavated with a No. 8 surgical-length latch round bur (RA-8SL [SS White]) (with a slow-speed handpiece very carefully until pulp horn was reached. A spoon excavator was used to remove remaining decay. At that point, the pulp started to hemorrhage. Sterile saline rinse was applied over the pulp horn, while a high-speed diamond bur was used to remove approximately 2 to 3 mm of pulp tissue, until healthy pulp tissue was reached and the bleeding ceased. CALASEPT 2% Chlorhexidine Solution (Nordiska Dental) (Figure 2b) was used to disinfect the coronal pulp by lightly irrigating the remaining pulp tissue coronal to pulpal floor (3% sodium hypochlorite can also be used as the irrigant to disinfect the coronal aspect of the pulp). Mineral trioxide aggregate (white) was mixed with xylocaine 2% (1:100,000 epinephrine) to a moist sandlike consistancy, dried with a 2 x 2 guaze, and gently packed directly on top of the coronal pulp with an amalgam carrirer and plugger. It is advisable to get at least 2 to 3 mm of MTA on top of the pulp, if possible. A moist cotton pellet and Cavit (3M ESPE) was placed on top of the MTA (Figure 2c). Mineral trioxide aggregate usually sets up hard in about 3 hours. Our patient’s mother was told to use over-the-counter ibuprofen if the area became sore after treatment. She was also told to take the child to her general dentist (GP) for a restorative evaluation and treatment within one month, and also given a postoperative appointment at our office.

Figure 2a. Tooth 30 pre-op with gross decay and open apices.	Figure 2b. CALASEPT 2% Chlorhexidine Solution (Nordiska Dental).
Figure 2c. Mineral trioxide aggregate pulpotomy with Cavit (3M ESPE).	Figure 2d. One month recall—patient asymptomatic and tooth is still vital.
Figure 2e. One-year recall—patient is still asymptomatic and tooth is vital.	Figure 2f. Two-year recall shows continued root formation.

Figure 2g. The distal root is completely closed and tooth is still vital at 3-year recall.

The patient returned to our office for a one-month recall (Figure 2d). The patient reported the tooth to be asymptomatic. Pulp testing was performed with Endo Ice and the tooth still tested vital. There was no percussion or palpation sensitivity, no sinus tract noted, and no mobility observed. Probing was 2 to 3 mm. It was noted that the patient still had the Cavit in place, so the patient’s mother was again reminded/advised to have the buildup restoration placed as soon as possible by the GP.
The patient returned for a one-year recall (Figure 2e). The patient still was reporting tooth No. 30 to be asymptomatic. A buildup and a stainless steel crown had been completed. Radiographically, there was evidence of continued root formation, and no pathology was noted. The pulp was tested and was still vital. There was no sinus tract noted or mobility and probing results remained at 2 to 3 mm.
Our patient returned for a 2-year recall appointment (Figure 2f) and was still reporting that the tooth was asymptomatic. Radiographically, it appeared that the distal root had completely closed, and the mesial root appeared to still be slightly open. The tooth was still vital to pulp testing, and there was no palpation or percussion sensitivity. There was no sinus tract noted or mobility, and periodontal probing remained at 2 to 3 mm. The patient’s mother was told that we would continue to follow her progress on a yearly basis. In addition, she was told, if signs/symptoms of pain and/or swelling would become associated with her tooth, to return for an evaluation and possible conventional endodontic treatment.
When our patient returned for her 3-year recall (Figure 2g), the distal root was completely closed. However, the mesial roots still appeared to be slightly open at the apex.

Case 2
Diagnosis and Treatment Planning—A 6-year-old female with a history of dental trauma presented to our office. A complicated crown fracture with a pulp exposure was evident, involving her right permanent central incisor (tooth No. 9) (Figure 3a). The apex was still open, and she was in pain. Her left permanent central incisor (tooth No. 8) was asymptomatic and pulp tested vital.
Synopsis of Clinical Treatment—Two carpules of 2% xylocaine 1;100,000 were adminstered to the patient via infiltation. Tooth no. 9 was isolated with a rubber dam and accessed. It was cleaned out and irrigated very carefully (with the same technique described in the previous case).

Figure 3a. Complicated crown fracture on tooth No. 9 with open apex.	Figure 3b. Mineral trioxide aggregate on glass slab.
Figure 3c. Amalgam carrier and MTA.	Figure 3d. Apexogenesis procedure completed with MTA.

Mineral trioxide aggregate (white) was removed from packet and placed on a glass slab (Figure 3b). Next, the MTA was mixed with 2% xylocaine (1:100,000 epinephrine) to a wet sand consistency. It was then slightly dried using a sterile 2 x 2 guaze to allow easier packing onto the already moist pulp with an amalgam carrier (Figure 3c). The MTA was placed directly on to the pulp with the amalgam carrier, and then compressed with a moist cotton pellet.
An apexogenesis procedure was completed utilizing the same clinical protocol as described above in Case 1 (Figure 3d). A cotton pellet and Cavit was placed into the access opening, and the patient was referred back to her general dentist for a permanent restoration.

Case 3
Diagnosis and Treatment Planning—A 7-year-old male presented with spontaneous pain associated with his left first permanent molar (tooth No. 19). There was a broken amalgam with recurrent decay. The apices were open on the both the mesial and distal roots (Figure 4a).
Synopsis of Clinical Treatment—Apexogenesis procedure was completed utilizing the same procedure from the previous cases. Cotton and Cavit were placed in the access opening (Figure 4b).

Figure 4a. Tooth 19 Pre-Op.	Figure 4b. Apexogensis using MTA on tooth 19.
Figure 4c. Six-month recall showing root starting to close.	Figure 4d. One-year recall showing continued root formation and length.

Figure 4e. A 2-year recall showing complete closure of the apex.

A 6-month recall was performed. The patient was asymptomatic, and a composite resin core and a stainless steel crown has been placed. Tooth pulp testing demonstrated that it was vital, and evidence of root closure was apparent (Figure 4c).
At the one-year recall, the patient was still asymptomatic and tooth pulp testing showed it was vital. In addition, evidence of further root closure was apparent (Figure 4d).
At the patient’s 2-year recall, the tooth was still asymptomatic and tooth pulp testing was vital. The roots appeared to be completely closed (Figure 4e).

CLOSING COMMENTS
Mineral trioxide aggregate, as a pulpotomy agent is excellent, despite the fact that is costly. One way in which the use of MTA can be made more cost effective is to carefully store unused portions of the powder from an opened packet in a sterilized empty film canister; this will prevent hydration and keep it fresh. (When the material was in the “experimental” phase in the early 1990s, it was sent out this way to the endodontists for trial use.)
As demonstrated in this case report article, the young and immature permanent tooth had an excellent capacity to respond to apexogenesis. This is true, whether dealing with caries or trauma, as long as the clinical treatment is performed quickly and properly. The goal is to treat the pulp before it becomes necrotic. Once necrotic, the treatment of pulpal injury becomes a more significant challenge for the clinician. If the pulp is vital and the apex is open, apexogenesis should be considered as the first option of treatment, not conventional endodontic treatment.
Apexogenesis is a vital pulp therapy that can be done to encourage continued physiological development and root end formation.

References

1. Fong CD, Davis MJ. Partial pulpotomy for immature permanent teeth, its present and future. Pediatr Dent. 2002;24:29-32.
2. Management of incompletely formed roots. In: Walton RE, Torabinejad M. Principles and Practice of Endodontics. 3rd ed. Philadelphia, PA: Saunders; 2002:388-404.
3. Hermann BW. Biologische Wurzelbehandlung. Frankfurt, Germany: Kramer; 1936.
4. Treatment of deep caries, vital pulp exposure, and pulpless teeth. In: McDonald RE, Avery DR, Dean JA. Dentistry for the Child and Adolescent. 8th ed. St. Louis, MO: Mosby; 2004:389-412.
5. Holland R, de Souza V, Nery MJ, et al. Reaction of rat connective tissue to implanted dentin tubes filled with mineral trioxide aggregate or calcium hydroxide. J Endod. 1999;25:161-166.
6. Schwartz RS, Mauger M, Clement DJ, et al. Mineral trioxide aggregate: a new material for endodontics. J Am Dent Assoc. 1999;130:967-975.
7. Dentsply Tulsa Dental. Material Safety Data Sheet (MSDS). ProRoot MTA (mineral trioxide aggregate) root canal repair material. Prepared February 1, 2002.
8. Ford TR, Torabinejad M, Abedi HR, et al. Using mineral trioxide aggregate as a pulp-capping material. J Am Dent Assoc. 1996;127:1491-1494.
9. Aeinehchi M, Eslami B, Ghanbariha M, et al. Mineral trioxide aggregate (MTA) and calcium hydroxide as pulp-capping agents in human teeth: a preliminary report. Int Endod J. 2003;36:225-231.
10. Torabinejad M, Hong CU, Lee SJ, et al. Investigation of mineral trioxide aggregate for root-end filling in dogs. J Endod. 1995;21:603-608.
11. Torabinejad M, Higa RK, McKendry DJ, et al. Dye leakage of four root end filling materials: effects of blood contamination. J Endod. 1994;20:159-163.

Dr. Short graduated from Morris Brown College with a BS in 1995. He received his DDS from Medical College of Georgia (MCG) School of Dentistry in 1999. In 2002, he earned his postdoctorate degree in endodontics from Nova Southeastern University. Dr. Short became a board certified endodontist in 2009. He is a Diplomate of the American Board of Endodontics and his private practice, Apex Endodontics PC, is located in Smryna, Ga. Dr. Short is also an expert consultant to the Georgia Board of Dentistry and an assistant clinical professor at MCG School of Dentistry. In addition, he has lectured nationally about various topics relating to endodontics. Dr. Short has received several prestigious awards and accolades throughout his career and is very philanthropic in his community, volunteering at various nonprofit organizations such as Camp Kudzu Inc, working with juvenile diabetes. Dr. Short has authored a book, Getting to the Root of Your Problem: 365 Days of Inspirational Thinking. He can be reached at dr.short@yahoo.com.

Disclosure: Dr. Short reports no disclosures.