Investigation of the validity of using 3D printed teeth to replace human teeth for in-vitro endodontic research

Kooanantkul, Chuta (2020). Investigation of the validity of using 3D printed teeth to replace human teeth for in-vitro endodontic research. University of Birmingham. M.Sc.

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Abstract

Introduction: Root canal obturation aims at eliminating the communication between the root canal and the peri-radicular tissues. Obturating materials fill the root canal space and the adequacy of obturation is usually assessed as a marker of sealer performance. One of the methods used to measure quality of obturation is the calculation of obturated volume of the root canal by microcomputed tomography (µCT). Human teeth are usually used for such analysis but the diversity in anatomy and the need of ethical approval limits their use. Human teeth with a particular anatomy can be 3-D printed with a polymer model being very popular for teaching and in vitro research. The polymer model is not suitable to test hydraulic calcium silicate (HCSC)-based sealers as it does not interact with the sealers and it also prevents surrounding moisture from reaching them. Thus, this research aimed to manufacture a root model composed of hydroxyapatite (HA), to assess the obturation efficacy of sealers and comparing this to that in contact with natural teeth and 3-D printed polymer teeth using µCT.

Methods: Sealers and GP were characterised by the scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDX). Forty-seven incisors and mesial roots of lower molars were sectioned at the cement-enamel junction, prepared with the Protaper Gold and scanned with µCT. One incisor and molar 3D data were selected as digital model for 3DPT. 40% and 45% of HA slurry were prepared and characterised by SEM, EDX and rheometer. HA-3DPT was printed with Admaflex-130 and characterised with SEM and EDX. Five lower premolars and five polymer incisors were used to test the effect of the moisture, position and temperature on µCT accuracy. Forty-five of each polymer and natural incisors and molars were divided into 9 groups equally and were obturated with either AH Plus (Dentsply Maillefer, Tulsa, OK, USA), Totalfill BC (FKG Dentaire SA, La Chaux-de-Fonds, Switzerland), BioRoot RCS (Septodont, Saint-Maur-des, Fossés, France) or Bio-C sealer (Angelus, Londrina, PR, Brazil) with either warm vertical compaction (WVC ) or single-cone technique. Teeth were scanned immediately after obturation, at 3-month and 6-month interval. Obturated roots were kept in Hank’s balanced salt solution (HBSS). HBSS was collected at 3 and 6 months to measure the calcium ion leaching with inductively coupled plasma mass spectroscopy (ICP-MS).

Results: The moisture content, positioning and temperature fluctuations inside the µCT chamber did not affect the mean root canal volume. 40% and 45% HA slurry had the same characteristics as the Admatec alumina slurry (control for printable slurry specific to the machine used). 45% HA slurry could be used to print the HA tooth model. The HA tooth model’s appearances including size and shape were similar to the digital model except it had no root canal. When comparing the same sealer obturated with different obturation technique, the polymer molar obturated with Totalfill BC WVC had significantly less gap and void volume percentages than the Totalfill BC with BC cone (p ≤ 0.05),
the Bio-C WVC had significantly less gap and void volume percentages than the Bio-C single-cone (p ≤ 0.05). When comparing the same obturation technique with different sealer, there was no significantly different between each group (p > 0.05). When comparing different sealer with different obturation technique, Both AH Plus WVC and Totalfill BC WVC had significantly less gap and void volume percentages than the BioRoot RCS single-cone in natural tooth (p ≤ 0.05). For the polymer molar, the Totalfill WVC had significantly less gap and void volume percentages than the Bio-C single-cone and the Bio-C WVC had significantly less gap and void volume percentages than the Totalfill BC cone (p ≤ 0.05). Gaps and voids volume percentages decreased in the AH Plus single-cone in natural teeth and increased in the BioRoot single-cone of natural incisors and Bio-C WVC of polymer incisors. The highest calcium ions released at 3 months was found in the Totalfill BC cone in every tooth type. At 6 months, the highest calcium ion release was found in the BioRoot RCS single-cone for both natural tooth types, Total fill BC cone for polymer incisors and Bio-C WVC for polymer molars.

Conclusion : Variations in pre-testing parameters had no effect on the µCT measurement. 40% and 45% HA slurry had potential to be 3D printed. Polymer teeth could be used in endodontic research instead of the natural teeth to assess the filling quality and amount of calcium ion leaching. Increasing the polymer teeth’s radiopacity could improve the reliability of the result. All HCSC-based sealers could be used to obturate the root canal with either single cone technique or WVC technique. Gutta-percha mass was still needed to adapt the sealers into the root canal wall and irregularity. The Totalfill BC and the BioRoot RCS obturated with single cone technique should be used whenever the clinician needs the effects of calcium ion released from the sealer.

Type of Work:

Thesis (Masters by Research > M.Sc.)

Award Type:

Masters by Research > M.Sc.

Supervisor(s):