Assessment of Pulpal Status in Primary Teeth Following Direct Pulp Capping in an Experimental Canine Model

Abstract

(1) Background: This study aimed to assess the pulpal response of primary teeth by pulse-oximetry (PO) in a canine model, following direct pulp capping (DPC). (2) Methods: Forty-eight primary teeth from eight canine subjects were divided into three treatment groups, based on the DPC material—calcium hydroxide (CH), MTA, BiodentineTM)—and three corresponding control groups. Data from PO pulp testing were correlated with laser Doppler flowmetry (LDF) testing, computer tomographic (CT) densitometry and histological analysis; the experiment lasted 14 days. (3) Results: SpO₂ recordings revealed statistically significant differences (p = 0.002, <0.05) between the treatment and control groups, and no significant differences (p = 0.257, >0.05) were observed between treatment groups. LDF recordings showed significant differences (p = 0.002, <0.05) between the treatment and control groups and identified significant differences between materials (p = 0.001, <0.05). CT densitometry indicated vital pulps in all teeth, with pulpal inflammation detected in 6/8 CH-capped teeth and 2/8 MTA-capped teeth. Histologic evaluation confirmed vital pulp in all specimens, with different degrees of inflammation. (4) Conclusions: Within its limitations, the present study confirms the diagnostic value of PO evaluation of pulpal status in primary teeth with histologic means after pulp-capping procedures in a canine model. However, various degrees of pulpal inflammation elicited by different pulp-capping materials seem not to correlate with the obtained PO values.

Keywords: LDF; pulp capping; pulse oximetry; vitality pulp testing.

Figure 1

SpO₂ recording in a canine subject: (a) liquid rubber dam isolation of teeth 804, 806 and 807 before SpO₂ recording; (b) SpO₂ recording in tooth 807 in low light conditions.

Figure 2

Acquisition of LDF signal using a double silicone impression for the stabilization of the probe and liquid rubber dam for the isolation of the pulpal signal from the periodontal contaminating signal.

Figure 3

LDF pulp signal recorded in tooth 807, 24 h after DPC (T1).

Figure 4

Radiographical image of the right mandible: (a) prior to DPC, (b) 14 days after DPC of teeth 804, 806 and 807.

Figure 5

Axial CT slice of 0.6 mm thickness for teeth 807 (14 days after Biodentine^TM DPC) and 707 (control) with pulp density measurements (expressed in HU), red arrow: conducted at the same level for both teeth (CT: 663 HU in tooth 807 and CT:817 HU in tooth 707).

Figure 6

SpO₂% in the treatment vs. control groups (T1–T3).

Figure 7

Dental pulp of dog primary teeth capped with different biomaterials (HE coloration): (a) CH– arrow = marked acute and chronic severe pulpal inflammation; D = dentin flakes; DB = dentinal bridge (100× magnification). (b) MTA—p = normal pulp tissue; arrow = minimal inflammatory reaction; hyperemic blood vessels; DB = dentinal bridge; OL = odontoblastic layer (100× magnification). (c) Biodentine^TM—p = normal pulp tissue; DB = dentinal bridge; OL = odontoblastic layer (200× magnification).