Histologic Examination of Teeth with Necrotic Pulps and Periapical Lesions Treated with 2 Scaffolds: An Animal Investigation

• The aim was to histologically compare the tissues generated when PRP or a blood clot with Gelfoam is placed into teeth with preexisting necrotic pulps and periapical lesions.
• Using scaffolds of PRP or blood clots resulted in more apical narrowing and hard tissue deposition versus when not using a scaffold.
• The use of PRP or blood clots as scaffolds results in the ingrowth of bone-like, cementum-like, and connective tissue in the apical third of the roots at inconsistent rates.

IntroductionTraditional pulp regeneration procedures that use a blood clot as a scaffold have produced histologic evidence of bone, cementum, and connective tissue growth within the root. Platelet-rich plasma (PRP) is a bioactive scaffold containing growth factors that enhance wound healing.AimThe aim of this study was to histologically compare the tissues generated when PRP or a blood clot is placed into teeth with preexisting necrotic pulps and periapical lesions.MethodsTwenty-four canine teeth from 6 immature ferrets were used. Two ferrets served as positive controls. Sixteen experimental canine teeth from 4 ferrets were infected, debrided, treated with a triple antibiotic paste, and randomly distributed to the following groups: group 1 (blood clot/Gelfoam), group 2 (PRP), and group 3 (no scaffold). At 3 months, the ferrets were sacrificed, and the tissues were evaluated histologically. Data were analyzed by using the Fisher exact test (P < .05).ResultsIn 3 of 6 teeth in the PRP group, 2 of 6 teeth in the blood clot group, and 1 of 4 teeth in the no scaffold group, an ingrowth of hard tissues was observed in the apical third of the roots. When using PRP or a blood clot as a scaffold, we found significantly more apical narrowing and hard tissue deposition in comparison to not using a scaffold (P < .05).ConclusionsThe use of PRP or blood clots as scaffolds results in the ingrowth of bone-like, cementum-like, and connective tissue in the apical third of the roots at inconsistent rates.