Pulp canal obliteration after replantation of avulsed immature teeth: a systematic review

Some clinical case reports have shown that immature permanent teeth with periradicular periodontitis or abscess can undergo apexogenesis after conservative endodontic treatment. A call for a paradigm shift and new protocol for the clinical management of these cases has been brought to attention. Concomitantly, a new population of mesenchymal stem cells residing in the apical papilla of permanent immature teeth recently has been discovered and was termed stem cells from the apical papilla (SCAP). These stem cells appear to be the source of odontoblasts that are responsible for the formation of root dentin. Conservation of these stem cells when treating immature teeth may allow continuous formation of the root to completion. This article reviews current findings on the isolation and characterization of these stem cells. The potential role of these stem cells in the following respects will be discussed: (1) their contribution in continued root maturation in endodontically treated immature teeth with periradicular periodontitis or abscess and (2) their potential utilization for pulp/dentin regeneration and bioroot engineering.

It has been proposed (Cvek 1992) that immature teeth are weakened by filling of the root canals with calcium hydroxide dressing and gutta-percha. The aim of the present study was to test the hypothesis that dentin in contact with calcium hydroxide would show a reduction in fracture strength after a certain period of time. Immature mandibular incisors from sheep were extracted and divided into two experimental groups. Group 1: the pulps were extirpated via the apical foramen. The root canals were then filled with calcium hydroxide (Calasept) and sealed with IRM(R) cement, and the teeth were then stored in saline at room temperature for 0.5, 1, 2, 3, 6, 9, or 12 months. Group 2: the pulps were extirpated and the root canals were filled with saline and sealed with IRM(R) cement. The teeth were then stored in saline for 2 months. Intact teeth served as controls and were tested immediately after extraction. All teeth were tested for fracture strength in an Instron testing machine at the indicated observation periods. The results showed a markedly decrease in fracture strength with increasing storage time for group 1 (calcium hydroxide dressing). The results indicate that the fracture strength of calcium hydroxide-filled immature teeth will be halved in about a year due to the root filling. The finding may explain the frequent reported fractures of immature teeth filled with calcium hydroxide for extended periods.

Outcome assessment of endodontic treatment is critical for appropriate case selection and treatment planning. However, reports on outcomes of nonsurgical endodontic treatment vary considerably. Epidemiological studies done in a large patient population and over a long follow-up period can provide the clinician with useful tools for clinical decision-making and assessment of tooth prognosis. In this study, outcomes of initial endodontic treatment done in 1,462,936 teeth of 1,126,288 patients from 50 states across the USA was assessed over a period of 8 yr. Treatment was done by private general practitioners and endodontists participating in the Delta Dental Insurance plan that insures approximately 14 million individuals in the USA. Overall, 97% of teeth were retained in the oral cavity 8 yr after initial nonsurgical endodontic treatment. The combined incidence of untoward events such as retreatments, apical surgeries, and extractions was 3% and occurred mostly within 3 yr from completion of treatment. Analysis of the extracted teeth revealed that 85% had no full coronal coverage. A significant difference was found between covered and noncovered teeth for all tooth groups tested (p < 0.001). In conclusion, it appears that initial nonsurgical endodontic treatment is a predictable procedure with high incidence of tooth retention after 8 yr.