A necrotic immature permanent tooth presents an appealing opportunity for regenerative endodontics. Rather than simply creating an apical barrier, the hope is to preserve the tooth while allowing continued root development and, ideally, restoring vital pulp-like tissue.
But when a regenerative endodontic procedure is labelled a clinical “success,” how much regeneration has actually occurred?
A new systematic review and meta-analysis has highlighted an important distinction between the two.
Researchers evaluated regenerative endodontic procedures (REPs) in permanent teeth with different degrees of root maturity, examining four separate outcomes: clinical success, tooth survival, complete apical closure and recovery of pulp vitality. They also investigated whether the initial diameter of the apex influenced these outcomes.
Ten clinical studies involving a total of 508 teeth were included. These comprised randomized controlled trials as well as prospective and retrospective clinical studies, with follow-up periods ranging from 12 to 52 months.
The overall clinical results were impressive.
Across 496 teeth, regenerative procedures achieved a pooled clinical success rate of 90%. Tooth survival was even higher—98% among 453 teeth.
At first glance, these figures appear to make a strong case for regenerative endodontics.
However, when the researchers looked beyond clinical success and tooth retention, the picture became considerably more complex.
Saving the tooth is not the same as regenerating the pulp
Complete apical closure occurred in only 53% of the teeth for which this outcome was reported. There was also considerable variation between studies.
Pulp vitality recovery was even less predictable.
Across 224 teeth, the pooled rate of vitality recovery was just 21%, with individual studies reporting rates ranging from 0% to 50%.
The authors therefore emphasise an important point: high clinical success and survival after regenerative treatment should not automatically be interpreted as evidence of true pulp-dentin regeneration.
A tooth may remain asymptomatic, demonstrate periapical healing and survive following treatment without necessarily recovering functional vital pulp tissue.
This distinction is particularly relevant when discussing regenerative treatment with patients. The clinical goal of retaining a symptom-free tooth may frequently be achieved, but the biological outcomes traditionally associated with regeneration appear much less predictable.
Does the size of the apex matter?
The researchers also explored whether initial apical diameter influenced treatment outcomes.
Interestingly, clinical success remained relatively high—above 80%—across different apical diameters. Tooth survival similarly remained above 90%, and neither showed a statistically significant relationship with increasing apical diameter.
This suggests that initial apical maturity may not have as strong an influence on basic clinical success and tooth retention as might be expected.
However, the biological outcomes told a different story.
Complete apical closure appeared to decrease as initial apical diameter increased, with the exploratory analysis suggesting higher closure rates in teeth with narrower apices than those with wider openings.
For pulp vitality recovery, the available evidence was too limited and variable to establish a clear relationship with apical diameter.
The authors caution that these findings should not be treated as definitive. Only 10 studies were included, just two specifically involved mature teeth, and methods used to measure apical diameter varied considerably between studies. The analysis relating apical size to outcomes should therefore be considered exploratory rather than evidence of a causal relationship.
There was another important source of uncertainty: even the definition of “pulp vitality” differed between studies. Some researchers used cold testing, others electric pulp testing and some laser Doppler flowmetry, making direct comparison difficult.
The findings are reassuring when the primary objective is clinical success and tooth preservation. Across the available studies, regenerative endodontic procedures demonstrated high rates of both.
But the review also provides an important reality check for the word “regeneration.”
Successful treatment does not necessarily mean that a functional pulp-dentin complex has been restored. Complete apical closure remains inconsistent, and recovery of pulp vitality appears considerably less predictable than clinical healing or tooth survival.
The authors therefore recommend careful case selection based on apical maturity and realistic communication with patients about what regenerative treatment can currently be expected to achieve.
Regenerative endodontic procedures showed approximately 90% clinical success and 98% tooth survival, but true biological outcomes were far less consistent: complete apical closure occurred in 53% of cases and pulp vitality recovery in only 21%.