Microbiological assessment of success and failure in pulp revitalization: a randomized clinical trial using calcium hydroxide and chlorhexidine gluconate in traumatized immature necrotic teeth

Figures & data

Table 1. Inclusion and exclusion criteria for the selection of patients.

Inclusion criteria	Exclusion criteria
Age 6–13 years	No history of dental trauma
Good general health	Medically compromised patients
All types of traumatic injuries to permanent incisors	All types of traumatic injuries to canines, premolars, molars
Open apex >1 mm	Open apex <1 mm
Immature root development (RDS 1–4)	Mature root development (RDS 5–6)
Pulp necrosis with/without apical periodontitis	Pre-operative root fracture
	Teeth with periodontal disease (probing depth ≥6 mm)
No history of endodontic treatment on the particular tooth (No previous access preparation)	Allergy to the root canal medicaments used during the treatment
Pulp space not needed for post or core restoration	Missing data due to lack of compliance
Good compliance of patient and guardians
Adequate coronal restoration with no signs of caries

Abbreviation: RDS: Root development stages; RDS: 1–4 = very immature; 5 = immature; 6 = mature (Tsilingaridis et al., 2016)

Figure 1. Flow chart of the treatment protocol and the sampling time points during the revitalization procedures.

Figure 2. Flow chart of data collection of eligible root canal samples.

Abbreviations: HOMD: Human Oral Microbiome Database (http://www.homd.org); PR: pulp revitalization

Figure 3. Average number of CFU per sample in the successful pulp revitalization cases(n = 29) vs the failed PR cases (n = 12) at each sampling time point (S2, S3, and S5).

Each bar represents the mean value of CFU/sample at the different sampling time points in the designated subgroup with the range of standard deviation. The differences between the subgroups were analysed by the Mann–Whitney U-test; statistically significant difference was accepted at the level <0.05 (^TMsignificant at 95%).

Abbreviations: Calcium hydroxide PR Success: successful pulp revitalization cases treated with calcium hydroxide; Calcium hydroxide PR Failure: failed pulp revitalization cases treated with calcium hydroxide; Chlorhexidine gluconate PR Success: successful pulp revitalization cases treated with chlorhexidine gluconate; Chlorhexidine gluconate PR failure: failed pulp revitalization cases treated with chlorhexidine gluconate; CFU/sample: colony forming units per sample; ns: not significant; S2: sample before root canal debridement; S3: sample after root canal debridement; S5: sample after root canal dressing.

Figure 4. Average number of taxa per sample in the successful pulp revitalization cases(n = 29) versus the failed pulp revitalization cases (n = 12) at each sampling time point (S2, S3, and S5).

Each bar represents the mean value of taxa/sample at the different sampling time points in the designated subgroup with the range of standard deviation. The differences between the subgroups were analysed by the Mann–Whitney U-test; statistically significant difference was accepted at the level <0.05 (^TMsignificant at 95%).

Abbreviations: Calcium hydroxide PR Success: successful pulp revitalization cases treated with calcium hydroxide; Calcium hydroxide PR Failure: failed pulp revitalization cases treated with calcium hydroxide; Chlorhexidine gluconate PR Success: successful pulp revitalization cases treated with chlorhexidine gluconate; Chlorhexidine gluconate PR failure: failed pulp revitalization cases treated with chlorhexidine gluconate; ns: not significant; S2: sample before root canal debridement; S3: sample after root canal debridement; S5: sample after root canal dressing; taxa/sample: numbers of taxa per sample.

Figure 5. Disinfection efficacy in the successful vs. failed pulp revitalization cases, calcium hydroxide and chlorhexidine subgroups.

The dots represent the individual value of disinfection efficacy. The boxes represent the range of standard deviation, the red lines in the boxes represent the median value per group, the whiskers represent the minimum and maximum values. The data set was analysed using the Kruskal–Wallis test. Statistically significant difference was accepted at the level <0.05.

Disinfection efficacy was calculated using the formula Efficacy=Log N₀/N, where N₀ represents the CFU/sample before root canal debridement at S2 and N represents the CFU/sample after root canal disinfection at S5. Data are presented with the limit of detection (<10).

Abbreviations: ns: not significant; PR success: successful pulp revitalization cases; PR failure: failed pulp revitalization cases.

Figure 6. Primary bacterial taxa from all samples before root canal debridement (S2) cultured in both outcomes of successful and failed pulp revitalization (n = 41).

Abbreviations: PR success: successful pulp revitalization cases; PR failure: failed pulp revitalization cases.

Figure 7. Phylum diversity between successful and failed pulp revitalization outcomes in relation to the substance used for the root canal disinfection.

Each colour in the boxes represents the proportions of representative taxa on phylum level expressed in percentages (%). The data set was analysed using the Z-test for proportions where comparisons were performed between the successful and failed outcomes of pulp revitalization. Statistically significant difference was accepted at the level <0.05.

Abbreviations: ns: not significant; PR success: successful pulp revitalization cases; PR failure: failed pulp revitalization cases.

Figure 8. Bacterial load on the phyla associated with both outcomes of pulp revitalization in the calcium hydroxide subgroup.

Abbreviations: ns: not significant; PR success: successful pulp revitalization cases; PR failure: failed pulp revitalization cases.

Figure 9. Bacterial load on the phyla level associated with both outcomes of pulp revitalization in the chlorhexidine subgroup.

Abbreviations: ns: not significant; PR success: successful pulp revitalization cases; PR failure: failed pulp revitalization cases.

Figure 10. Bacterial taxa cultured in all cases from the calcium hydroxide subgroup (pulp revitalization treatment – success and failure at all time points).

Abbreviations: PR success: successful pulp revitalization cases; PR failure: failed pulp revitalization cases.

Figure 11. Bacterial taxa cultured in all cases from the chlorhexidine subgroup (pulp revitalization treatment – success and failure at all time points).

Abbreviations: PR success: successful pulp revitalization cases; PR failure: failed pulp revitalization cases.