Vitamin C sounds like it should give injectable platelet-rich fibrin an extra regenerative boost. But in this randomized trial, adding it did not produce a statistically significant healing advantage over injectable platelet-rich fibrin alone.

Periapical periodontitis is an inflammatory condition that develops secondary to pulpal infection, most commonly arising from dental caries or traumatic injury. Conventionally, this condition is managed by root canal treatment. However, pulp extirpation may compromise the structural durability of endodontically treated teeth, rendering them more prone to fracture and reinfection.

These limitations underscore the essential role of the pulp tissue in preserving tooth vitality and long-term dental health. The favorable outcomes of regenerative endodontic techniques in immature necrotic teeth include resolution of clinical manifestations, healing of the periapical tissues, and continuation of root maturation.

Those outcomes have encouraged extending these approaches in mature teeth with closed apices. However, most of the scientific evidence on pulp regeneration in mature teeth was coming from low evidence case reports or case series. Among clinicians, blood clot-mediated revascularization remains the most commonly employed approach.

Clinical studies have demonstrated that blood clots achieve success rates comparable to alternative scaffold materials. However, blood clot formation may be unpredictable and provides a relatively limited source of growth factors, which may restrict its clinical applicability.

In 2014, injectable platelet-rich fibrin, or i-PRF, was introduced aimed to improve the biological properties of PRF. This flowable form of PRF was produced by using plastic tubes and reduced centrifugation speeds for shorter periods of time: seven hundred revolutions per minute for three minutes.

After application, fibrinogen-rich fluid in i-PRF gradually converts into a growth factor-rich PRF clot. That clot continuously liberates these factors over a period of ten to fourteen days, comparable to the PRF which provides sustained growth factor release up to seven days after its application.

Due to its liquid form, i-PRF can be used alone or combined with bioactive molecules such as vitamin C. Vitamin C, also referred to as L-ascorbic acid, is a water-soluble micronutrient essential for collagen synthesis and extracellular matrix formation.

Experimental studies have demonstrated that vitamin C enhances the proliferative capacity of mesenchymal stem cells and promotes collagen synthesis at concentrations up to two hundred micromolar. Despite the promising biological characteristics of injectable platelet-rich fibrin, the potential synergistic effect of combining i-PRF with vitamin C in regenerative endodontic therapy has not been sufficiently evaluated, particularly in mature necrotic teeth with closed apices.

Evidence comparing CBCT with conventional radiographs in regenerative endodontic outcomes remains limited. The primary objective was to assess the healing potential of injectable platelet-rich fibrin combined with vitamin C as a scaffold in regenerative endodontic procedure of mature necrotic single-rooted teeth using CBCT.

The secondary aims were to compare CBCT radiographic outcomes with those obtained from two-dimensional periapical radiographs. The secondary aims also included assessing postoperative pain and clinical outcomes following regenerative endodontic procedures. The study was conducted as a prospective, parallel-group, double-blinded, randomized controlled trial with a one-to-one allocation ratio.

The trial was registered at ClinicalTrials.gov with the identifier NCT05585359 and was registered on fourteen October twenty twenty-two, following approval by the institutional review board of the Faculty of Dentistry, Cairo University. Written informed consent was obtained from all participants prior to their enrollment in the study.

Participant recruitment, treatment, and follow-up were conducted at an outpatient clinic between April twenty twenty-three and January twenty twenty-five. Sample size estimation was determined according to the primary outcome measure using data from a previous study.

According to that study, at least twelve teeth, or twelve participants, were required per group, assuming a normally distributed outcome, with a standard deviation of five and an expected mean difference of six. Subjects were randomly allocated to either the study group, in which regenerative endodontic procedures were conducted using i-PRF plus ascorbic acid, or the group in which i-PRF alone was used.

Operator blinding was not feasible due to the nature of the interventions. However, participants were masked to the assigned intervention or control group. The preparation of injectable platelet-rich fibrin, with or without the addition of Vitamin C supplementation, was performed out of their view following blood withdrawal.

Patients were eligible if they were medically healthy, aged between eighteen and forty-five years, and presented with mature permanent maxillary or mandibular anterior teeth diagnosed with pulp necrosis. Eligible teeth exhibited a negative response to cold testing and were accompanied by swelling or without swelling and or a sinus tract, along with radiographic evidence of periapical radiolucency.

All included teeth had fully developed roots with closed apices. Upon removal of the double antibiotic paste and drying of the canal, ten milliliters of whole venous blood were collected from the patient’s median cubital vein. The blood was transferred into plain plastic test tubes that did not contain anticoagulant.

Based on the volume of injectable platelet-rich fibrin collected following centrifugation, the corresponding amount of vitamin C was calculated. For each one milliliter of i-PRF, zero point five milliliters, approximately two hundred fifty micromolar, of vitamin C was mixed with the i-PRF.

The primary outcome measure was radiographic healing of the periapical lesion, assessed quantitatively by measuring the lesion area in square millimeters using CBCT at baseline and twelve months. Secondary outcomes included radiographic healing assessed using CBCT periapical index scores, two-dimensional radiographic assessment of lesion area, clinical outcomes, and postoperative pain.

CBCT scans were obtained at baseline and twelve months postoperatively using the same CBCT unit with standardized parameters. Bone healing was evaluated by measuring the periapical lesion area in square millimeters in both sagittal and coronal planes using the area measurement tool of the OnDemand CBCT software.

The final lesion area was calculated as the mean of the two measurements. Numerical data were assessed for normality by examining their distribution and using the Kolmogorov-Smirnov and Shapiro-Wilk tests. All variables demonstrated a non-normal, non-parametric distribution.

Accordingly, numerical data were presented as median, range, mean, and standard deviation. A total of twenty-eight participants were randomly allocated into two groups, with fourteen participants per group. During follow-up, two participants from the control group were not available for the periapical healing assessment.

One participant could not be contacted at the six-month follow-up despite attempts to reach the participant. The second participant reported fracture of the treated tooth before the scheduled three-month follow-up, and clinical examination revealed fracture of the restoration with loss of part of the tooth structure and the presence of a sinus tract.

The case was considered a treatment failure due to reinfection and was subsequently managed with conventional root canal treatment. At baseline, no statistically significant difference was observed between the intervention and control groups. The median pre-operative values were twenty-eight point seven in the intervention group and twenty-nine point zero in the control group, with no statistically significant difference, P equals zero point seven three four.

Within-group analysis demonstrated a statistically significant reduction from pre-operative to post-operative values in both groups, with P equals zero point zero zero one for each. The magnitude of change was large in the intervention group and in the control group, indicating a substantial improvement over time irrespective of the treatment modality.

The findings demonstrated significant periapical lesion reduction over time in both groups, with no statistically significant difference between them, indicating that both scaffolds promoted healing. Postoperative pain profiles were also comparable between groups. Two-dimensional radiographic assessment revealed a statistically significant difference between groups at baseline, with smaller lesion sizes observed in the intervention group.

That difference was no longer apparent at any postoperative time point, as both groups demonstrated significant lesion reduction over time. Although the intervention group showed a numerically greater reduction at six, nine, and twelve months, the differences between the groups were not statistically significant.

The most notable between-group difference was observed at nine months, when the intervention group demonstrated a greater mean reduction in lesion area than the control group, accompanied by a moderate effect size of zero point seven three. However, this difference did not reach statistical significance, with P equal to zero point zero seven seven.

The relatively modest sample size may have reduced the statistical power to detect subtle differences between the treatment groups. Although the follow-up period was sufficient to assess early healing trends, it may not fully represent long-term regenerative outcomes or the stability of periapical healing over extended periods.

Another limitation of the study is the absence of a conventional blood clot control group. The findings therefore cannot determine whether i-PRF, either alone or supplemented with vitamin C, provides superior clinical or radiographic outcomes compared with conventional blood clot-based regenerative endodontic procedures.

The findings should be interpreted as a comparison between the two investigated i-PRF formulations, and broader clinical generalization should be made with caution. Future randomized clinical trials directly comparing i-PRF, with or without vitamin C, with conventional blood clot scaffolds and incorporating longer follow-up periods are warranted.

Within the limitations of this randomized controlled trial, both injectable platelet-rich fibrin alone and i-PRF supplemented with vitamin C were associated with favorable clinical and radiographic outcomes when used as scaffolds in regenerative endodontic treatment of necrotic mature teeth with chronic apical periodontitis.

No statistically significant differences were observed between the groups with respect to periapical healing, clinical outcomes, or postoperative pain. Both treatment protocols were associated with favorable clinical outcomes, and no adverse events were observed during the follow-up period.

The addition of vitamin C to i-PRF did not demonstrate a statistically significant additional clinical or radiographic benefit under the conditions of the study. Therefore, the potential added value of vitamin C as an adjunct to i-PRF remains uncertain and warrants further investigation.

The absence of a conventional blood clot control group and the lack of assessment of pulp sensibility and other regenerative parameters limit the ability to draw definitive conclusions regarding true pulp regeneration. Those limitations also restrict conclusions regarding the superiority of i-PRF-based scaffolds over conventional regenerative approaches.

Both injectable platelet-rich fibrin approaches were associated with healing and favorable clinical outcomes, but vitamin C added no statistically significant benefit under the study conditions. The modest sample, short follow-up, and missing conventional blood-clot control limit how broadly the result can be applied.