Histologic characterization of regenerated tissues after pulp revascularization of immature dog teeth with apical periodontitis using tri-antibiotic paste and platelet-rich plasma.

INTRODUCTION: This study evaluates histologically the efficacy of 4 revascularization protocols in necrotic-infected immature dog teeth with apical periodontitis (AP). METHODS: Forty double-rooted immature premolar teeth from 4 female Beagle dogs aged 5 months were used. Four teeth were left untouched as negative controls; the other 36 teeth were infected to develop pulp necrosis and AP. Four teeth were left untreated and assigned to the positive control group. The last 28 teeth were randomly assigned into four experimental groups of 8 teeth, each one treated with a different treatment protocol: A1, sodium hypochlorite (SH)+blood clot (BC); A2, SH+platelet-rich plasma (PRP); B1, SH+modified tri-antibiotic paste (mTAP)+BC; B2, SH+mTAP+PRP. The animals were sacrificed, histologic sections were prepared and three parameters were assessed: (1) presence or absence of new hard tissue on the internal root dentinal walls, (2) presence or absence of continued apical closure, and (3) presence or absence of vital tissue within the canal space. RESULTS: Significant differences (p<0.05) between the four experimental groups were evident in the percentage of teeth showing histological apical closure (34.5%) and vital tissue within the canal space (68.8%). Group B2 showed the maximal improvement in the three variables assessed (p<0.05). Group A1 showed the minimum percentages in the three parameters assessed (p<0.05). CONCLUSIONS: These results suggest that an intracanal dressing of mTAP, and the use of PRP as scaffold, improves the success rate of the revascularization procedure.

Pulp Revascularization of Immature Dog Teeth with Apical Periodontitis Using Triantibiotic Paste and Platelet-rich Plasma: A Radiographic Study.

INTRODUCTION: This study evaluates radiographically the efficacy of 4 revascularization protocols in necrotic-infected immature dog teeth with apical periodontitis (AP). METHODS: Forty double-rooted immature premolar teeth from 4 female beagle dogs aged 5 months were used. Four teeth were left untouched as negative controls; the other 36 teeth were infected to develop pulp necrosis and AP following different treatment protocols. Four teeth were left untreated and assigned to the positive control group, and the last 28 teeth were randomly assigned into 4 experimental groups of 8 teeth: A1, sodium hypochlorite (NaOCl) + a blood clot; A2, NaOCl + platelet-rich plasma (PRP); B1, NaOCl + modified triantibiotic paste (mTAP) + a blood clot; and B2, NaOCl + mTAP + PRP. Teeth were monitored radiographically for 6 months regarding healing of periapical radiolucencies, thickening of the dentinal walls, and apical closure of roots. RESULTS: Significant differences (P < .05) between the 4 groups were evident in the percentage of teeth showing improvement of periapical radiolucencies (62.5%), continued radiographic thickening of radicular walls (53.1%), radiographic apical closure (43.8%), and deposition of hard tissue on radicular dentin walls (53.1%). Group B2 showed maximal improvement in the 3 variables assessed (P < .05). Group A1 showed the minimum percentages in the 3 parameters assessed (P < .05). CONCLUSIONS: These results suggest that an intracanal dressing of mTAP and the use of PRP as scaffold improves the success rate of the revascularization procedure.

Root canal disinfection of immature dog teeth with apical periodontitis: Comparison of three different protocols.

OBJECTIVES: The present in vivo study was designed to assess the efficacy of 3 root canal disinfection protocols in immature dog teeth with apical periodontitis (AP). MATERIAL AND METHODS: Forty immature premolars with pulp necrosis and AP of five Beagle dogs were used. Three experimental disinfection protocols were established. After irrigation with 40 ml 5.25% sodium hypochlorite using the Endovac system, in Group 1 canals were flushed with QMix solution; in Group 2, canals were flushed with QMix solution and 2% chlorhexidine gel dressing was placed for two weeks; and in Group 3, triantibiotic paste dressing was placed for two weeks. Canals were sampled after periapical lesions were radiographically visible (S1), after the first disinfection session (S2) and, in groups 2 and 3, after dressing (S3). RESULTS: After the first session of the disinfection protocol (S2), there was significant (p < 0.05) bacterial reduction in the three experimental groups. Microorganisms were absent in 100% of S2 samples in groups 1 and 2, and in 75% of group 3 (p > 0.05). After dressing, 87.5% of the S3 samples showed increased bacterial count: in group 2, CFU counts (median = 891) were significantly higher than in group 3 (median = 18) (p = 0.03). CONCLUSIONS: In immature dog teeth with AP, root canal irrigation using QMix solution, with or without chlorhexidine gel dressing, or a triantibiotic paste dressing, provides the same level of disinfection than irrigation with 5.25% sodium hypochlorite alone in only one session. Key words:Apical periodontitis, chlorhexidine, Endovac, immature teeth, QMix solution, root canal disinfection, triantibiotic paste.