Regenerative endodontics-The management of immature non-vital teeth following trauma or pulpal infection is a challenge. Traditional approaches can result in brittleness, with teeth susceptible to root fracture. This article discusses more biologically-based treatment approaches that offer regenerative possibilities and continued development of tooth structure.
The management of immature non-vital teeth following trauma, or pulpal infection secondary to caries, or dental anomalies such as dens evaginatus is a treatment dilemma and challenge for dentists. Traditionally, the treatment prescribed for immature non-vital teeth was thorough debridement of the root canal system followed by filling it with materials such as Ca(OH)2 in order to induce an apical barrier formation – i.e. apexification. In the last decade materials such as MTA have been used increasingly to create a barrier immediately. Following such treatments once a barrier is created, conventional obturation with gutta percha can then be performed in these teeth. These techniques however do not produce any increase in thickness of dentine or any increase in root length, and no qualitative or quantitative improvement of root dimensions is possible. Furthermore, studies have shown that intracanal Ca(OH)2 can induce brittleness of the tooth structure due to its hygroscopic and proteolytic properties, and following successful apexification these teeth are frequently susceptible to root fracture. Therefore, it is imperative that more biologically-based treatment approaches, which offer regenerative possibilities and continued development of tooth structure, be explored.
Pulp tissue in immature teeth with open apices has a rich blood supply, and given the right conditions, may have the potential for regeneration following pulpal damage. This is in fact not a novel concept in pulp biology, and had been discussed previously in the dental scientific literature by Nygaard-Østby as early as 1961.
Recent case reports have shown that immature non-vital teeth can demonstrate continued root development under favourable conditions that promote healing of apical pulp tissue. A classic case report by Iwaya and co-workers showed that five months after antimicrobial therapy, thickening of the dentinal walls and apical closure were seen in an immature second mandibular premolar with necrotic pulp. Other case series showed similar outcomes of continued maturation of root apices in teeth which had previously developed extensive periradicular lesions with sinus tract formation prior to treatment. In all these cases, some form of antimicrobial therapy, using antibiotic pastes and irrigation with sodium hypochlorite, was employed, serving as the disinfectant for the root canals. Also, in many of these cases mechanical instrumentation was not employed, and disinfection of the root canal was achieved purely through chemical means.
Various combinations of topical antibiotics have been proposed for use in the disinfection of root canals. The feasiblity for use of antibiotics as intracanal medicaments for disinfection of root canal spaces is supported by controlled animal studies carried out in dogs. One of the most well documented antibiotic combinations found to be effective against intracanal bacterial in infected root canals is the “3 mix-MP” triple antibiotic paste, which consists of ciprofloxacin, metronidazole and minocycline. In animal studies, the use of the “3 mix-MP” triple antibiotic paste was seen to be effective in the disinfection of immature teeth with apical periodontitis, and was able to induce apical closure of infected dog teeth with open apices. There are also case series in humans which have shown this method to be a viable alternative to the traditional use of Ca(OH)2 as the intracanal medicament of choice. The benefits are that the problems associated with alteration in the dentine structure and high pH of Ca(OH)2, which could potentially destroy the properties of multipotent cells associated with the continued root development in the apical papilla, can be avoided.
What the above-mentioned series of case reports also demonstrate is that vital pulp rich in regenerative potential is present at the most apical portion of the root, and that open apex non-vital teeth with periradicular pathology can still undergo apexogenesis. Successful removal of infected coronal pulp and disinfection of the root canal would provide a favourable healing environment for regeneration of pulpal tissue, thus allowing the vital pulpal cells at the apical papilla region to proliferate into the empty root canal space. This invariably further emphasises the importance of a sterile root canal as a pre-requisite for a conducive environment necessary for pulpal regeneration.
Clinical technique used for Regenerative Endodontic Therapy.
There are currently no standardised protocols for regenerative endodontic therapy (RET) in the treatment of non-vital immature teeth with wide open apices. Minor modifications to the procedures have been made by various groups who have carried out clinical case studies. The outline of the technique proposed in general is as follows:
All procedures are carried out under administration of local anesthetic and rubber dam isolation.
Pulpal extirpation and copious chemical irrigation of root canals with disinfectants such as 3% hydrogen peroxide or 2.5% sodium hypochlorite is performed for 30 minutes.
Minimal or no filing to the root canal is carried out to prevent further weakening of the existing dentinal walls.
The tooth is then dried and triple antibiotic paste is used as an intracanal medicament and sealed in the root canal. Caution should be exercised during the placement of antibiotic pastes to ensure that the application is below the cervical margins in order to prevent discolouration of the crown due to staining properties of minocycline.
The tooth is then sealed temporarily and a review is scheduled in 2-3 weeks to ascertain if the disinfection procedure has been successful. It is essential that disinfection of the root canal is carried out until there is no evidence of purulent discharge, sinus tract or infection, and a repeat of the disinfection process should be performed if the root canal is still not infection-free.
At the next appointment, the canals are re-irrigated copiously with saline. A sterile 23-gauge needle with a length of 2 mm beyond the working length is pushed past the confines of the root canal into the periapical tissues to intentionally induce bleeding into the root canal. The bleeding is then allowed to fill the root canal.
When frank bleeding is evident at the cervical portion of the root canal, a cotton pellet is then inserted 3– 4mm into the canal below the cervical margins and held there for about 7-10 mins to allow formation of a blood clot in the apical 2/3rds of the canal. This blood clot acts as a scaffold, rich in growth and differentiation factors, that are essential to aid in the ingrowth of viable tissue into the pulpal space and for wound healing processes.
The access is then sealed with materials such as MTA or Glass ionomer cements to prevent coronal leakage, extending about 4 mm into the coronal portion of the root canal
Periapical radiographs are then taken as baseline record. This is essential for comparison with future 6-monthly radiographs to ascertain continued root development and thus success of the treatment.
Indications/contraindications
As with all treatment, in order to increase success rates, case selection is paramount. This technique is indicated for all immature teeth which are non-vital, or partially necrotic teeth with open apex. There should not be concurrent signs of other pathological root resorption, eg. replacement root resorption which could otherwise affect the prognosis of the tooth. The safety of this technique however has not been evaluated for use in patients with medical conditions such as cardiac problems or bleeding disorders. Therefore, at this present moment, it would be prudent to avoid carrying out such procedures in medically compromised patients at risk of bacteremia or with abnormal bleeding tendencies.
advantages/disadvantages
Regenerative endodontic methods have the potential for regenerating both pulp and dentine tissues and therefore may offer an alternative method to save teeth that may have compromised structural integrity and hence poor long-term prognosis. The advantages of regenerative endodontic therapy are:
Shorter treatment time and therefore reduction in treatment fatigue, especially in young patients in which this clinical situation often presents.
Cost-effective due to the decreased number of visits.
Obturation is not required.
Achieves continued root development and strengthening of the tooth structure due to reinforcement of lateral dentinal walls and is therefore a more biological approach to treatment.
Success/survival rates
At this point in time, there are an inadequate number of studies in the dental literature looking at the success and survival rates of regenerative endodontic therapy procedures. However, from the limited evidence, successful treatment outcomes appear to be associated with the width of the open apices and young age of the patient. Most of the clinical evidence available is still at case report levels, and it may be timely to carry out prospective evaluative randomised clinical trials on the efficacy of medicaments used and treatment protocol employed as more evidence continues to be generated on this subject.
Conclusion
The potential scope of SCAP in continued root maturation in immature teeth should be exploited in the clinical management of non vital teeth with incomplete root development. This could potentially be a future clinical approach to replace the need and dependence of the dental profession on conventional endodontics that do not enhance the root structure, which means that such teeth remain prone to root fractures and hence usually have a poor long term prognosis.
The management of immature non-vital teeth following trauma, or pulpal infection secondary to caries, or dental anomalies such as dens evaginatus is a treatment dilemma and challenge for dentists. Traditionally, the treatment prescribed for immature non-vital teeth was thorough debridement of the root canal system followed by filling it with materials such as Ca(OH)2 in order to induce an apical barrier formation – i.e. apexification. In the last decade materials such as MTA have been used increasingly to create a barrier immediately. Following such treatments once a barrier is created, conventional obturation with gutta percha can then be performed in these teeth. These techniques however do not produce any increase in thickness of dentine or any increase in root length, and no qualitative or quantitative improvement of root dimensions is possible. Furthermore, studies have shown that intracanal Ca(OH)2 can induce brittleness of the tooth structure due to its hygroscopic and proteolytic properties, and following successful apexification these teeth are frequently susceptible to root fracture. Therefore, it is imperative that more biologically-based treatment approaches, which offer regenerative possibilities and continued development of tooth structure, be explored.
Pulp tissue in immature teeth with open apices has a rich blood supply, and given the right conditions, may have the potential for regeneration following pulpal damage. This is in fact not a novel concept in pulp biology, and had been discussed previously in the dental scientific literature by Nygaard-Østby as early as 1961.
Recent case reports have shown that immature non-vital teeth can demonstrate continued root development under favourable conditions that promote healing of apical pulp tissue. A classic case report by Iwaya and co-workers showed that five months after antimicrobial therapy, thickening of the dentinal walls and apical closure were seen in an immature second mandibular premolar with necrotic pulp. Other case series showed similar outcomes of continued maturation of root apices in teeth which had previously developed extensive periradicular lesions with sinus tract formation prior to treatment. In all these cases, some form of antimicrobial therapy, using antibiotic pastes and irrigation with sodium hypochlorite, was employed, serving as the disinfectant for the root canals. Also, in many of these cases mechanical instrumentation was not employed, and disinfection of the root canal was achieved purely through chemical means.
Various combinations of topical antibiotics have been proposed for use in the disinfection of root canals. The feasiblity for use of antibiotics as intracanal medicaments for disinfection of root canal spaces is supported by controlled animal studies carried out in dogs. One of the most well documented antibiotic combinations found to be effective against intracanal bacterial in infected root canals is the “3 mix-MP” triple antibiotic paste, which consists of ciprofloxacin, metronidazole and minocycline. In animal studies, the use of the “3 mix-MP” triple antibiotic paste was seen to be effective in the disinfection of immature teeth with apical periodontitis, and was able to induce apical closure of infected dog teeth with open apices. There are also case series in humans which have shown this method to be a viable alternative to the traditional use of Ca(OH)2 as the intracanal medicament of choice. The benefits are that the problems associated with alteration in the dentine structure and high pH of Ca(OH)2, which could potentially destroy the properties of multipotent cells associated with the continued root development in the apical papilla, can be avoided.
What the above-mentioned series of case reports also demonstrate is that vital pulp rich in regenerative potential is present at the most apical portion of the root, and that open apex non-vital teeth with periradicular pathology can still undergo apexogenesis. Successful removal of infected coronal pulp and disinfection of the root canal would provide a favourable healing environment for regeneration of pulpal tissue, thus allowing the vital pulpal cells at the apical papilla region to proliferate into the empty root canal space. This invariably further emphasises the importance of a sterile root canal as a pre-requisite for a conducive environment necessary for pulpal regeneration.
Clinical technique used for Regenerative Endodontic Therapy.
There are currently no standardised protocols for regenerative endodontic therapy (RET) in the treatment of non-vital immature teeth with wide open apices. Minor modifications to the procedures have been made by various groups who have carried out clinical case studies. The outline of the technique proposed in general is as follows:
All procedures are carried out under administration of local anesthetic and rubber dam isolation.
Pulpal extirpation and copious chemical irrigation of root canals with disinfectants such as 3% hydrogen peroxide or 2.5% sodium hypochlorite is performed for 30 minutes.
Minimal or no filing to the root canal is carried out to prevent further weakening of the existing dentinal walls.
The tooth is then dried and triple antibiotic paste is used as an intracanal medicament and sealed in the root canal. Caution should be exercised during the placement of antibiotic pastes to ensure that the application is below the cervical margins in order to prevent discolouration of the crown due to staining properties of minocycline.
The tooth is then sealed temporarily and a review is scheduled in 2-3 weeks to ascertain if the disinfection procedure has been successful. It is essential that disinfection of the root canal is carried out until there is no evidence of purulent discharge, sinus tract or infection, and a repeat of the disinfection process should be performed if the root canal is still not infection-free.
At the next appointment, the canals are re-irrigated copiously with saline. A sterile 23-gauge needle with a length of 2 mm beyond the working length is pushed past the confines of the root canal into the periapical tissues to intentionally induce bleeding into the root canal. The bleeding is then allowed to fill the root canal.
When frank bleeding is evident at the cervical portion of the root canal, a cotton pellet is then inserted 3– 4mm into the canal below the cervical margins and held there for about 7-10 mins to allow formation of a blood clot in the apical 2/3rds of the canal. This blood clot acts as a scaffold, rich in growth and differentiation factors, that are essential to aid in the ingrowth of viable tissue into the pulpal space and for wound healing processes.
The access is then sealed with materials such as MTA or Glass ionomer cements to prevent coronal leakage, extending about 4 mm into the coronal portion of the root canal
Periapical radiographs are then taken as baseline record. This is essential for comparison with future 6-monthly radiographs to ascertain continued root development and thus success of the treatment.
Indications/contraindications
As with all treatment, in order to increase success rates, case selection is paramount. This technique is indicated for all immature teeth which are non-vital, or partially necrotic teeth with open apex. There should not be concurrent signs of other pathological root resorption, eg. replacement root resorption which could otherwise affect the prognosis of the tooth. The safety of this technique however has not been evaluated for use in patients with medical conditions such as cardiac problems or bleeding disorders. Therefore, at this present moment, it would be prudent to avoid carrying out such procedures in medically compromised patients at risk of bacteremia or with abnormal bleeding tendencies.
advantages/disadvantages
Regenerative endodontic methods have the potential for regenerating both pulp and dentine tissues and therefore may offer an alternative method to save teeth that may have compromised structural integrity and hence poor long-term prognosis. The advantages of regenerative endodontic therapy are:
Shorter treatment time and therefore reduction in treatment fatigue, especially in young patients in which this clinical situation often presents.
Cost-effective due to the decreased number of visits.
Obturation is not required.
Achieves continued root development and strengthening of the tooth structure due to reinforcement of lateral dentinal walls and is therefore a more biological approach to treatment.
Success/survival rates
At this point in time, there are an inadequate number of studies in the dental literature looking at the success and survival rates of regenerative endodontic therapy procedures. However, from the limited evidence, successful treatment outcomes appear to be associated with the width of the open apices and young age of the patient. Most of the clinical evidence available is still at case report levels, and it may be timely to carry out prospective evaluative randomised clinical trials on the efficacy of medicaments used and treatment protocol employed as more evidence continues to be generated on this subject.
Conclusion
The potential scope of SCAP in continued root maturation in immature teeth should be exploited in the clinical management of non vital teeth with incomplete root development. This could potentially be a future clinical approach to replace the need and dependence of the dental profession on conventional endodontics that do not enhance the root structure, which means that such teeth remain prone to root fractures and hence usually have a poor long term prognosis.
